WO2016127324A1 - 一种降低峰均比的方法、装置、设备和*** - Google Patents

一种降低峰均比的方法、装置、设备和*** Download PDF

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Publication number
WO2016127324A1
WO2016127324A1 PCT/CN2015/072695 CN2015072695W WO2016127324A1 WO 2016127324 A1 WO2016127324 A1 WO 2016127324A1 CN 2015072695 W CN2015072695 W CN 2015072695W WO 2016127324 A1 WO2016127324 A1 WO 2016127324A1
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Prior art keywords
subcarrier
phase
subcarriers
phase factor
reserved
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PCT/CN2015/072695
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English (en)
French (fr)
Inventor
吴涛
刘晟
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华为技术有限公司
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Priority to PCT/CN2015/072695 priority Critical patent/WO2016127324A1/zh
Priority to EP15881486.3A priority patent/EP3247079A4/en
Priority to CN201580072679.8A priority patent/CN107251500A/zh
Publication of WO2016127324A1 publication Critical patent/WO2016127324A1/zh
Priority to US15/674,154 priority patent/US20170338989A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2614—Peak power aspects
    • H04L27/2621—Reduction thereof using phase offsets between subcarriers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2614—Peak power aspects
    • H04L27/262—Reduction thereof by selection of pilot symbols
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2626—Arrangements specific to the transmitter only
    • H04L27/2627—Modulators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/10—Small scale networks; Flat hierarchical networks
    • H04W84/12—WLAN [Wireless Local Area Networks]

Definitions

  • Embodiments of the present invention relate to communication technologies, and in particular, to a method, apparatus, device, and system for reducing a peak-to-average ratio.
  • Wireless Fidelity (English: Wireless Fidelity; referred to as WiFi) system (or wireless LAN system), through 802.11a, 802.11b, 802.11d, 802.11n and 802.11ac and other versions, the technology is more and more mature, providing The system transmission speed is also getting larger and larger, and 802.11ac can support 1Gbps at present. On the other hand, due to its unique flexibility, it is getting more and more applications in home and business environments.
  • next-generation WiFi system 802.11ax two new technologies have been introduced to increase the throughput of the system to meet the increasing communication needs:
  • the allocated bandwidth will be multiplied, and up to four 20Ms can be allocated, that is, 80M bandwidth is allocated to the user at a time.
  • orthogonal frequency division multiple access (English: Orthogonal Frequency Division Multiple Access; referred to as: OFDMA)
  • a 20M bandwidth is divided into 64 subcarriers (English: Tone or Subcarrier), which is used to transmit Orthogonal Frequency Division Multiplexing (OFDM) symbols.
  • OFDM Orthogonal Frequency Division Multiplexing
  • all of the remaining subcarriers used for transmitting data are used to transmit data of one user.
  • OFDMA orthogonal frequency division multiplexing
  • the OFDMA system is a multi-carrier modulation system, which has the advantages of high frequency band utilization and strong multipath fading resistance.
  • the multi-carrier modulation signal is obtained by superimposing signals of different frequencies and different amplitudes. Therefore, the multi-carrier modulation system generally has a large peak-to-average power ratio (English: Peak-to-Average Power Radio; referred to as: PAPR).
  • PAPR is generally used to define the power characteristics of the input signal. Since the PAPR of the signal of the input amplifier is too high, the above-mentioned problems of out-of-band radiation and in-band distortion are caused.
  • next-generation WiFi system in order to support OFDMA, a 256-point FFT is used in the 20M bandwidth, and the maximum supported bandwidth is increased from 20M to 80M.
  • the PAPR problem will deteriorate, and a specific processing method must be considered.
  • Fig. 1 is a simulation diagram of the distribution of the complementary cumulus distribution function (English: Complementary Cumulative Distribution Function; CCDF). For details, see the different Fast Fourier Transform (English: Fast Fourier Transform; FFT) PAPR results for points, where the total number of different subcarriers corresponding to different FFT points:
  • CCDF Complementary Cumulative Distribution Function
  • 64 points correspond to the existing 20M bandwidth, and the PAPR distribution of 64 subcarriers,
  • 256 points correspond to the existing 20M bandwidth, and the PAPR distribution of 256 subcarriers
  • 1024 points correspond to 80M bandwidth, PAPR distribution of 1024 subcarriers
  • the PAPR is increased by 2 ⁇ 3dB compared with the original 64-point FFT, that is, the PAPR becomes larger, which affects the performance of the system.
  • the embodiment of the invention provides a method for reducing the peak-to-average ratio, and the method is applied to a wireless fidelity WiFi system, including:
  • Subcarriers of orthogonal frequency division multiplexing OFDM symbols carrying data to be transmitted are divided to obtain a plurality of partitions;
  • the data transmitted on each of the plurality of partitions is multiplied by a corresponding phase factor and transmitted.
  • the embodiment of the invention provides a device for reducing a peak-to-average ratio, and the device is applied to a wireless fidelity WiFi system, including:
  • a dividing module configured to carry subcarriers of orthogonal frequency division multiplexing OFDM symbols of data to be transmitted Divide to obtain multiple partitions
  • a determining module configured to determine a plurality of phase factors corresponding to the plurality of blocks, wherein the plurality of phase factors are used to reduce a peak-to-average ratio of the OFDM symbols;
  • a transmitting module configured to transmit the multiple phase factors by using a specific subcarrier of the OFDM symbol, multiply each of the plurality of partitions by a corresponding phase factor, and transmit.
  • Embodiments of the present invention provide a device for reducing a peak-to-average ratio, the device being applied to a wireless fidelity WiFi system, including: a processor, a memory, a transmitter, and a bus, wherein the processor, the memory, and the transmitter pass through a bus connection for data transmission, the memory for storing data processed by the processor;
  • the processor is configured to divide a subcarrier of an orthogonal frequency division multiplexing OFDM symbol that carries data to be transmitted, to obtain a plurality of partitions, and determine a plurality of phase factors corresponding to the plurality of partitions, where the multiple phase factors are used by the processor. To reduce the peak-to-average ratio of the OFDM symbols;
  • the transmitter is configured to transmit the plurality of phase factors using a specific subcarrier of the OFDM symbol; multiply each of the plurality of partitions by a corresponding phase factor and transmit.
  • the embodiment of the invention provides a method for reducing the peak-to-average ratio, and the method is applied to a wireless fidelity WiFi system, including:
  • the embodiment of the invention provides a device for reducing a peak-to-average ratio, and the device is applied to a wireless fidelity WiFi system, including:
  • a receiving module configured to receive an OFDM symbol, where a subcarrier of the OFDM symbol is divided into multiple partitions, where the multiple partitions correspond to multiple phase factors, and the multiple phase factors are used by And reducing a peak-to-average ratio of the OFDM symbol, where a specific subcarrier of the OFDM symbol carries the plurality of phase factors, and each of the plurality of partitions carries a multiplied by a corresponding phase Factor data;
  • An acquiring module configured to obtain the multiple phase factors according to the signal carried by the specific subcarrier
  • a recovery module configured to obtain data transmitted by the OFDM symbol according to the phase factor and the plurality of partitions.
  • Embodiments of the present invention provide a device for reducing a peak-to-average ratio, the device being applied to a wireless fidelity WiFi system, including: a processor, a memory, a receiver, and a bus, wherein the processor, the memory, and the receiver pass through a bus connection for data transmission, the memory for storing data processed by the processor;
  • a receiver configured to receive an Orthogonal Frequency Division Multiplexing (OFDM) symbol, where a subcarrier of the OFDM symbol is divided into a plurality of partitions, where the plurality of partitions correspond to a plurality of phase factors, and the plurality of phase factors are used by And reducing a peak-to-average ratio of the OFDM symbol, where a specific subcarrier of the OFDM symbol carries the plurality of phase factors, and each of the plurality of partitions carries a multiplied by a corresponding phase Factor data;
  • OFDM Orthogonal Frequency Division Multiplexing
  • a processor configured to obtain the multiple phase factors according to the signal carried by the specific subcarrier; and obtain data of the OFDM symbol transmission according to the phase factor and the plurality of partitions.
  • multiplying each of the plurality of partitions by a corresponding phase factor is a process of reducing PAPR for a plurality of partitions (or the OFDM symbols), specifically, each bearer in each partition
  • the subcarrier of the transmitted data is multiplied by the phase factor corresponding to the block and then transmitted.
  • the specific subcarrier is a reserved subcarrier, wherein the reserved subcarrier is a subcarrier reserved in a subcarrier of the OFDM symbol; wherein the reserved subcarrier carries phase factor information, and thus the transmission does not need to be multiplied by a phase factor.
  • the reserved subcarrier carries phase factor information, and thus the transmission does not need to be multiplied by a phase factor.
  • the specific subcarrier is a pilot subcarrier; further, transmitting the multiple phase factors by using the specific subcarrier of the OFDM symbol includes: carrying multiple phase factors on the pilot subcarrier for transmission, where The frequency subcarrier carries the product of the corresponding phase factor and the pilot signal of the plurality of phase factors. It should be understood that when the phase factor is transmitted by using the pilot subcarrier, the phase factor is not required to be converted and modulated, but the pilot signal is directly multiplied by the phase factor to be transmitted on the pilot subcarrier, and then carried. The transmission is performed on pilot subcarriers, wherein some or all of the pilot subcarriers may be used for transmission.
  • the steps of the transmitting end and the receiving end are corresponding or similar, and the OFDM symbol that is sent by the transmitting end and that reduces the PAPR processing and the phase factor signal carried in the OFDM symbol are
  • the receiving end recovers the phase factor from the OFDM symbol accordingly, and then recovers the data carried by the OFDM symbol by using the phase factor.
  • the embodiment of the present invention does not limit the processing of one OFDM symbol, and multiple OFDM symbols may be unified and processed according to the method provided by the embodiment of the present invention.
  • two OFDM symbols may be uniformly divided and uniformly determined.
  • the phase factor is uniformly transmitted on a specific subcarrier of the two OFDM symbols or transmitted by using the transmission method provided by the present invention.
  • the phase factor may also be separately determined, and then uniformly transmitted by using the transmission method provided by the present invention.
  • the transmission method includes at least There are several types: (1) direct transmission phase factor; (2) conversion of phase factor into phase factor information, modulation of phase factor information and transmission; (3) conversion of phase factor into phase factor information, encoding phase factor information After modulation, transmission, optionally, the modulated data can also be repeated.
  • the method for reducing the peak-to-average ratio provided by the embodiment of the present invention can be adapted to a multi-input multi-output (MIMO) system, that is, to transmit in each stream in MIMO.
  • MIMO multi-input multi-output
  • the method provided by the embodiment of the present invention may be applied to the OFDM symbol, and the multiple OFDM symbols of the multiple streams may also be applied together to apply the method provided by the embodiment of the present invention.
  • the specific subcarriers may be one or more, and specifically, the reserved subcarriers or pilot subcarriers may be one or more. Specifically, it is necessary to use some or all of the specific subcarriers (that is, which specific subcarriers or the number of specific subcarriers are specifically selected) to transmit the phase factor, which can be flexibly determined according to the transmission reliability or the actual requirement, and only examples are given below.
  • the invention is not limited.
  • a specific subcarrier having a specific subcarrier number in the present invention is only exemplary, and specific subcarriers are not limited to specific subcarriers, and may be determined according to actual conditions or reserved according to standards in actual applications.
  • the location determination of the subcarriers or pilot subcarriers is within the scope of the present invention as long as the method of the present invention is applied to a particular subcarrier.
  • the QPSK, the QAM, and the like in the present invention are only examples of the modulation mode.
  • the specific modulation mode may also be phase shift keying modulation, differential modulation, energy modulation, or other common modulation modes, which is not limited by the present invention.
  • the block coding, the BCH coding, and the like in the present invention are only examples of the coding mode, and the specific coding mode may also be RS coding, cyclic coding, convolutional coding, Reed-Muller coding, or other common coding modes, which is not limited by the present invention. .
  • the subcarriers of the orthogonal frequency division multiplexing OFDM symbols carrying the data to be transmitted are divided to obtain a plurality of partitions; and a plurality of phase factors corresponding to the plurality of partitions are determined, wherein the plurality of phase factors A method for reducing a peak-to-average ratio of an OFDM symbol; transmitting a plurality of phase factors by using a specific subcarrier of the OFDM symbol; multiplying each of the plurality of partitions by a corresponding phase factor, and transmitting lose.
  • a phase factor for reducing the peak-to-average ratio of the OFDM symbol is also transmitted by using a specific subcarrier in the OFDM symbol, so that the required end of the OFDM symbol can be transmitted.
  • the information of the peak-to-average ratio is reduced, so that the PAPR of the transmitted OFDM symbol can be reduced and the transmission reliability can be improved without making a small adjustment.
  • Figure 1 is a simulation diagram of PAPR CCDF distribution with different FFT point changes
  • 2 is a conceptual diagram of OFDM and OFDMA
  • FIG. 3 is a schematic diagram of the principle of PTS
  • FIG. 3a is a simulation diagram of PAPR distribution after adopting the PTS method in an 80M bandwidth and a 1024 subcarrier;
  • FIG. 4 is a schematic diagram of a technical principle of applying a PTS in an OFDMA system
  • FIG. 5 is a schematic diagram of transmission mode 1
  • FIG. 6 is a schematic diagram of a transmission mode 2
  • FIG. 7 is a schematic diagram of a transmission mode 3
  • 8 is a schematic diagram of a frame structure in the 802.11 standard
  • FIG. 9 is a schematic diagram of a principle of transmitting phase factor information in a WiFi system
  • 10 is a schematic diagram of specific implementation manners of several transmission phase factor information
  • Figure 10a is a schematic diagram showing the distribution of reserved subcarriers in the frequency domain
  • FIG. 10b is a schematic diagram of a division manner of 1024 subcarriers in 802.11ax;
  • Figure 11a is a simulation diagram of the PAPR CCDF distribution of the 802.11ad system
  • FIG. 11 is a simulation diagram of reducing PAPR according to an embodiment of the present invention.
  • FIG. 12 is a schematic diagram of an apparatus for reducing a peak-to-average ratio according to an embodiment of the present invention.
  • FIG. 13 is a schematic diagram of an apparatus for reducing a peak-to-average ratio according to an embodiment of the present invention.
  • FIG. 14 is a schematic diagram of another method for reducing a peak-to-average ratio according to an embodiment of the present invention.
  • FIG. 15 is a schematic diagram of another apparatus for reducing a peak-to-average ratio according to an embodiment of the present invention.
  • FIG. 16 is a schematic diagram of another apparatus for reducing a peak-to-average ratio according to an embodiment of the present invention.
  • the embodiment of the present invention provides a method and apparatus for reducing a peak-to-average ratio, that is, using a specific subcarrier in an OFDM symbol to transmit a phase factor, and other data transmission.
  • the subcarrier block is multiplied by the corresponding phase factor, so that the transmitting end minimizes the PAPR of the subcarrier transmitting the data by selecting an appropriate phase factor, and the receiving end can pass the phase factor (or phase factor) in the received specific subcarrier.
  • Information complete data recovery, thus reducing the system peak-to-average ratio.
  • the specific subcarrier in the embodiment of the present invention may be a reserved subcarrier or a pilot subcarrier.
  • the method for reducing the peak-to-average ratio provided by the embodiment of the present invention may be a site, an access point, or a terminal or a network node, which is not limited thereto.
  • the access point (abbreviation: AP, English: Access Point) in the embodiment of the present invention is also referred to as a wireless access point or hotspot.
  • the AP may be a terminal device or a network device with a WiFi chip.
  • the AP may be a device that supports the 802.11ax system.
  • the AP may be configured to support multiple WLANs such as 802.11ac, 802.11n, 802.11g, 802.11b, and 802.11a (English: Wireless Local Area Network, Chinese: Wireless LAN) Standard equipment.
  • the station (abbreviation: STA, English: Station) in the embodiment of the present invention may be a wireless communication chip, a wireless sensor, or a wireless communication terminal; for example, a mobile phone supporting WiFi communication function, and a tablet supporting WiFi communication function.
  • a set-top box that supports WiFi communication and a computer that supports WiFi communication.
  • the site can support the 802.11ax system. Further optionally, the site supports multiple WLAN formats such as 802.11ac, 802.11n, 802.11g, 802.11b, and 802.11a.
  • each square of the frequency domain data portion represents data carried by one subcarrier.
  • OFDM except for the 0 intermediate frequency (0 IF corresponding DC signal, no data transmitted on it), all subcarriers except the pilot subcarrier and the guard subcarrier, which are displayed in gray in the left half of Fig. 2, are used for transmission.
  • a user's data that is, the white portion of the frequency domain data can be used to transmit single-user data, and then the IFFT for the frequency domain data is the time domain data.
  • subcarriers For OFDMA, except for the 0 intermediate frequency and guard subcarriers shown in gray in the right half of Figure 2, the remaining subcarriers are divided into N subbands (English: band), which may also be called resource blocks (English: Resource Unit) Abbreviation: RU), different subbands are used to transmit data of different users, wherein each subband contains pilot subcarriers; that is, subcarriers in the frequency domain data can be allocated to different users for transmission.
  • Data for example, a sub-band composed of subcarriers of a horizontal line padding portion is used to transmit data of User 1, and a sub-band composed of subcarriers of a vertical line padding portion is used for transmitting data of User 2, and then performing IFFT on the frequency domain data. For time domain data.
  • the input data is divided into blocks for OFDMA transmission, and each data block (ie, the data block corresponding to the user) is carried on the sub-band for transmission, and the sub-band has two different
  • the method of partitioning method differs in the granularity of the subband, wherein the granularity of the subband and the granularity of the data block are corresponding.
  • the data block here is different from the block of the corresponding phase factor below.
  • the data block here is for multi-user partitions, each sub-band can transmit one user's data, so the size of the data block on the sub-band To match the subband.
  • the first seed band is divided into two modes: each sub-band occupies 26 sub-carriers, and correspondingly, each data block occupies 26 sub-carriers, and the sub-band division manner is as follows:
  • a 256-point FFT transform is used in the 20M bandwidth, and 26 subcarriers are divided into one data subband.
  • the subbands are divided as follows:
  • the number of guard subcarriers on both sides is 5, 6, that is, there are 11 subcarriers for the guard band;
  • the subcarrier corresponding to the 0 intermediate frequency does not transmit a signal
  • the 1024-point FFT transform is used in the 80M bandwidth, and is divided into 1024 subcarriers, and the subcarriers are allocated as follows:
  • the number of guard subcarriers on each side is 5, 6, that is, there are 11 subcarriers used for the guard band, and no data is transmitted;
  • each sub-band occupies 52 sub-carriers
  • each data block occupies 52 sub-carriers
  • the sub-band division manner is as follows:
  • 256-point FFT transform is used in the 20M bandwidth, 52 subcarriers are divided into one sub-band, and the sub-band is divided.
  • the points are as follows:
  • the guard subcarriers on both sides are 5, 6, that is, there are 11 subcarriers for the guard band;
  • the subcarrier corresponding to the 0 intermediate frequency does not transmit a signal
  • the 1024-point FFT transform is used in the 80M bandwidth, and is divided into 1024 subcarriers, and the subcarriers are allocated as follows:
  • the number of guard subcarriers on each side is 5, 6, that is, there are 11 subcarriers used for the guard band, and no data is transmitted;
  • a subcarrier that is not used is referred to as a reserved subcarrier (English: Reserved Tone), which may also be referred to as a reserved subcarrier, and may also be referred to as a residual subcarrier (English: Left Tone): for example, the first type
  • the 24 unused subcarriers in the division mode and the second division mode are precisely because the reserved subcarriers are not used to transmit data, so that the reserved subcarriers can be used to transmit the phase factor which reduces the peak-to-average ratio of the current OFDM symbol.
  • 26 subcarriers are used as a basic unit of scheduling, which may be referred to as a subband or resource block.
  • the specific 20M bandwidth, 40M bandwidth, and 80M bandwidth design are as follows:
  • a 20M bandwidth is divided into 256 subcarriers, and 26 subcarriers are divided into one subband for transmitting data.
  • the subcarriers are allocated as follows:
  • the protection subcarriers on both sides are 5, 6, that is, there are 11 subcarriers for the protection band, and no data is transmitted;
  • the remaining 8 subcarriers are unused.
  • a 40M bandwidth is divided into 512 subcarriers.
  • the subcarriers are allocated as follows:
  • the guard subcarriers on both sides are 12, 11, that is, there are 23 subcarriers for the guard band, and the number of transmissions is not transmitted. according to;
  • 18 subbands are used to transmit data, occupying a total of 468 reserved subcarriers.
  • a total of 16 reserved subcarriers are unused.
  • the 80M bandwidth is divided into 1024 subcarriers.
  • the subcarriers are allocated as follows:
  • the guard subcarriers on both sides are 13, 12, that is, there are 25 subcarriers for the guard band, and no data is transmitted;
  • a total of 37 sub-bands are used to transmit data, occupying a total of 926 sub-carriers;
  • the remaining 32 reserved subcarriers are unused.
  • the PAPR of the time domain signal is much higher than that of a single carrier system, which causes many problems, such as reducing the efficiency of the transmitter power amplifier and reducing the digital/analog converter and the analog/
  • the signal-to-noise ratio of the digital converter is one of the most unfavorable factors in the OFDM or OFDMA system itself. Therefore, for OFDM or OFDMA systems, it is often required to perform specific processing to reduce PAPR.
  • the commonly used methods in products include pre-distortion and clipping.
  • FIG. 3 is a schematic diagram of the PTS principle, as shown in Figure 3:
  • the input data X is divided into N blocks, which are respectively x1, x2, ..., xN;
  • phase factor is:
  • Adding a cyclic prefix (English: Cyclic Prefix; abbreviated as CP) to the symbol obtained after the addition, to obtain an OFDM symbol;
  • the PAPR of the output OFDM symbol is minimized; therefore, if the PPR is used to reduce the PAPR, the phase factor needs to be determined, and the phase factor information needs to be transmitted (the phase factor needs to be converted into the phase factor information). ) so that the receiver can receive it Phase factor information to recover data.
  • the PTS processing at the transmitting end is as follows:
  • the PAPR of the sequence y(n) is defined as: That is, the ratio of the maximum power to the average power.
  • the selection or determination of the phase ⁇ m is the core of the PTS algorithm.
  • the following two typical algorithms are taken as an example to describe the selection or determination of the phase ⁇ m .
  • M the number of blocks
  • the first step setting a signal corresponding to the phase of the block is 1, block 2 phase signals corresponding to j, 3 phase signal corresponding to the block of e j ⁇ , the phase of the signal corresponding to the block 4 e -j ⁇ ;
  • ⁇ can also be a collection of the other four phases, such as
  • the second step is to traverse the various combinations to get the best PAPR result, which is the result of PAPR minimum:
  • the detailed design for the WiFi standard is based on this method, or ⁇ m from the set. That is From the collection ⁇ 1, j, -1, -j ⁇ or The value in the middle is explained as an example.
  • y(n) corresponds to a sequence of data on the OFDM symbol with the number of received subcarriers being N;
  • phase factor information needs to be transmitted so that the receiving end can further process, thereby reducing the PAPR of the OFDM symbol.
  • determining the plurality of phase factors corresponding to the plurality of segments comprises: taking a plurality of phase factors from the finite set to minimize the PAPR after the plurality of tiles are multiplied by the plurality of phase factors.
  • the limited set can be or Or other similar or simply deformed collections.
  • phase factor in the embodiment of the present invention may also be referred to as a phase shift factor, a weighting factor, a weighting coefficient, etc., which indicates a PAPR-reduced coefficient selected when applying the PTS, which may not only be expressed as a phase.
  • the form may also be in the form of other complex or real numbers, and the embodiment of the present invention is not limited thereto.
  • FIG. 3a is a PAPR distribution simulation diagram using the PTS method for 80M bandwidth and 1024 subcarriers. As shown in FIG. 3a, after the PTS method, the PAPR of the 1024 subcarrier OFDM signals and the OFDM signals of the 64 subcarriers are equivalent, so that the PTS method can effectively alleviate the problem of PAPR increase due to the increase of the number of subcarriers.
  • the application of PTS technology in practice has a big obstacle, which affects its application in practical systems. Since the data carried on each OFDM symbol is different in an actual system, the phase factors corresponding to different OFDM symbols are different after the PTS algorithm is used. At the receiving end, if the phase factor corresponding to each OFDM symbol is not known, the original before the PTS processing cannot be restored. The signal does not properly demodulate the signal. If the phase factor corresponding to each OFDM symbol is to be transmitted, a large bandwidth is required, which affects the transmission efficiency of the system. Due to this factor, the application of the PTS algorithm in practical systems is limited.
  • the PAPR of the system increases, thereby affecting system performance.
  • the PTS algorithm can solve the above problem of PAPR increase, but there is a difficulty in transmitting phase factor information to the receiver without increasing the bandwidth.
  • the present invention provides a method for transmitting a phase factor to a receiving end without adding extra bandwidth by using a specific subcarrier, so that the PAPR problem solved by using PTS is actually applied in practice.
  • PTS technology can be applied to reduce the PAPR of the system.
  • the specific process is as follows:
  • each upward arrow indicates a subcarrier, and only 16 arrows are shown in the figure, which is only a schematic, but in practice, There are more or less subcarriers, which are not limited in the embodiment of the present invention. For example, in a WiFi system, every 20M can be divided into 64 subcarriers or 256 subcarriers.
  • the bandwidth of the OFDM symbol in FIG. 4 be 80M, a total of 1024 subcarriers, and 20M correspond to one transport block, a total of four blocks.
  • the subcarriers in one OFDM symbol are divided into multiple transport blocks.
  • the 80M bandwidth is divided into 1024 subcarriers, and the subcarriers have a sequence number starting from 0, and increasing from the low frequency subcarrier to the high frequency subcarrier, as shown in FIG.
  • the leftmost subcarrier is the 0th subcarrier, which is sequentially sorted to the right by the first subcarrier, the second subcarrier, ... until the rightmost subcarrier is the 1023th subcarrier.
  • the first transport block includes 0th to 255th subcarriers, as shown in block 1 of FIG. 4; the second transport block includes 256th to 511th subcarriers, as shown in block 2 of FIG. 4; the third transport block includes The 512th to 767th subcarriers are as shown in block 3 of FIG. 4; the fourth transport block includes the 768th to 1023th subcarriers, as shown in block 4 of FIG.
  • sequence numbers of the 1024 subcarriers may also be numbered from -511 to 512, such that the subcarrier with sequence number 0 is exactly 0 intermediate frequency.
  • the corresponding phase factor of each block is determined to minimize the corresponding PAPR, for example, the phase factor is taken from a finite set, and the finite set may be
  • the phase factor information is transmitted so that the receiver recovers the data by receiving the phase factor information, and the specific processing is as follows:
  • the subcarriers used for transmitting data in each transport block are multiplied by the phase factor corresponding to the transport block, for example, the subcarriers in block 1 of FIG. 4 are multiplied by the phase factor corresponding to block 1. Multiplying the subcarriers in block 2 by the phase factor corresponding to block 2 The subcarrier in block 3 is multiplied by the phase factor corresponding to block 3. The subcarrier in block 4 is multiplied by the phase factor corresponding to block 4.
  • the pilot subcarriers are not subjected to phase shift processing, that is, the pilot subcarriers are not multiplied by a phase factor;
  • Phase factor information is transmitted on the reserved subcarriers, wherein the reserved subcarriers of each transport block transmit phase factor information for the transport block.
  • the receiver is processed as follows:
  • the phase factor carried on the reserved subcarriers on each transport block is obtained, and the specific acquisition method is related to the manner of transmitting the phase factor information, that is, how to transmit the phase factor information on the reserved subcarriers, and the application and transmission manner Corresponding acquisition mode, for example, transmitting the corresponding phase factor information by using QAM on the reserved subcarrier, and then applying the demodulated QAM manner to obtain corresponding phase factor information;
  • the subcarrier signals of the transmission data of each transport block are multiplied by the conjugate of the phase factor to eliminate the influence of the phase shift;
  • the processing procedure of the transmitting end is as follows:
  • the data mapped on the subcarriers input into one OFDM symbol is divided into a plurality of subblocks.
  • the corresponding bearer signal is 0 or a random signal, that is, the reserved subcarrier is not occupied or used to transmit data, and the x(n) corresponding to the reserved subcarrier is 0 or a random signal.
  • the phase factor information that is, the x(n) corresponding to the reserved subcarrier is no longer 0 or a random signal, but becomes the phase factor information obtained in 3).
  • x m (n) at this time is that x(n) generated in 4) is obtained according to formula (1), that is, x(n) corresponding to the reserved subcarrier in x m (n) is also The phase factor information obtained in 3) is replaced.
  • the receiving end is processed as follows:
  • y(n) y(n), (m-1)*L ⁇ n ⁇ m*L-1, when pilot information or phase factor information is transmitted on subcarrier n;
  • phase factor of the present invention will be described below. Among them, how to transmit the phase factor on the reserved subcarriers on each transport block, specifically the following three transmission methods:
  • Transmission mode 1 - direct transmission phase factor method
  • phase factor or phase factor of the transport block is transmitted directly on the reserved subcarriers of each transport block.
  • the same phase factor can be repeatedly transmitted on several reserved subcarriers, and generally the same phase factor is transmitted on 3 or 4 reserved subcarriers to provide sufficient transmission reliability;
  • the channel information is first used to recover the phase factor corresponding to each transport block, and the subcarrier signals of the transmission data of each transport block are multiplied by the conjugate of the phase factor to eliminate the influence of the phase factor;
  • FIG. 5 is a schematic diagram of a transmission mode 1.
  • a phase factor corresponding to the transmission block is transmitted on four non-contiguous reserved subcarriers on a certain transport block.
  • the reason why the discontinuous reserved subcarriers are selected is to avoid the influence of frequency selective weakening.
  • the following two transmission modes also utilize discontinuous reserved subcarriers to avoid the influence of frequency selective weakening.
  • only the reserved subcarriers for transmitting the phase factor are listed in FIG. 5.
  • the distribution and number of other subcarriers are not limited in the embodiment of the present invention.
  • FIG. 5 is for a certain transport block, like FIG. The case of multiple transport blocks or other transport blocks may be similarly obtained by referring to FIG. 5.
  • the transmission mode 2 and the transmission mode 3 are also for a certain transport block, and multiple transport blocks or other transport blocks may be used. The method of referring to the corresponding transmission mode is similarly obtained, and details are not described herein again.
  • the transmission mode 2 utilizes an energy modulation (or energy detection) scheme and is encoded and transmitted on the basis of energy detection. Specifically, when the signal is not transmitted on the reserved subcarrier, the corresponding bit 0 (or 1) is transmitted, and when the signal is transmitted, the corresponding bit 1 (or 0) is received; when the signal energy detected on the reserved subcarrier is greater than the preset threshold, the received signal is obtained. Bit 1 (or 0), otherwise get bit 0 (or 1).
  • energy modulation or energy detection
  • one of the two subcarriers on the transport block does not transmit a signal, and the other transmits a signal, and the corresponding code is 01, and the corresponding phase factor is The corresponding transmitted energy signal is 01.
  • the same signal is transmitted with 4 sets of 8 reserved subcarriers.
  • the transmission mode 3 uses a differential modulation method to carry a phase factor corresponding to each transmission block by a phase difference between the same subcarriers on adjacent symbols.
  • phase factor on the sth symbol of a certain transport block signal is The corresponding phase information on the reserved subcarrier is ⁇ s .
  • the other subcarriers are differentially modulated in a similar manner, except that the limit information corresponding to the subcarriers on the first OFDM symbol may be different.
  • the last long training field (English: Long Training Field; LTF for short) or Short Training Field (English: Short Training Field; STF) can be used as the first OFDM symbol. It is the reference signal.
  • the first OFDM data symbol used for transmission may also be used as the first OFDM symbol, and the symbol does not adopt the processing method for reducing the peak-to-average ratio according to the present invention, and the fixed pilot signal is transmitted on the reserved subcarrier.
  • the signals transmitted on the reserved subcarriers are all 1.
  • differential modulation is to transmit a corresponding phase factor in two adjacent subcarriers.
  • the phase factor on the sth symbol of a certain transport block signal is The two adjacent reserved subcarrier numbers are k and k+1, respectively, and the pilot signals transmitted thereon are p k and Where p k is a known pilot signal.
  • phase factor or phase factor information converted into phase factor
  • coding may be further introduced, that is, the phase factor (or phase factor information converted into phase factor) to be transmitted is first encoded. Then use the above three transmission methods for transmission.
  • the (16,8) block coding can be used for encoding, and 16 bits are output, wherein the (16,8) block coding indicates that the input information bits are eight and the coding block degree is 16.
  • the (16,8) block coding indicates that the input information bits are eight and the coding block degree is 16.
  • DQPSK/QPSK modulation it takes 8 reserved subcarriers to transmit. Further, if there are 24 reserved subcarriers available, the DQPSK/QPSK modulated data may be repeated 3 times, and the mapping is transmitted on 24 reserved subcarriers.
  • DQPSK in the embodiment of the present invention is only one type of differential modulation, and may also be used. It is a differential modulation method. Similarly, QPSK is only one type of modulation, and other modulation methods such as QAM can also be used.
  • the foregoing transmission manner is that a reserved subcarrier in each transport block transmits a phase factor of the transport block, but it is also possible to transmit a phase factor of all transport blocks by using part or all of the reserved subcarriers, that is,
  • the phase factor of which transport block is reserved for the subcarrier transmission is not limited, and the specific implementation method can be obtained by referring to the above transmission manner.
  • FIG. 8 is a schematic diagram of a frame structure in the 802.11 standard, as shown in FIG. 8, and the related descriptions of the fields are as follows:
  • Short Training Field (English: Short Training Field; STF): used for receiving signals synchronously by the receiver, including symbol synchronization and frequency synchronization;
  • Long training field (English: Long Training Field; LTF for short): used for receiver channel estimation and channel information acquisition;
  • Signaling field (English: Signal Field) / Service Field (English: Service Field): used to carry control signaling, including basic information such as code modulation mode;
  • Data field (English: Data Field): channel information carrying the transmission;
  • Tail & Padding Used to fill the tail bits so that the transmitted signal data can fill an integer multiple of the OFDM symbol.
  • the signaling field/service field needs to be modified. Specifically, a bit may be added to the field, and when the bit is the first value, The PTS technology provided by the embodiment of the present invention is used. When the bit is the second value, the method for reducing the PAPR provided by the embodiment of the present invention is not used. For example, when the bit is 1, the method for reducing the PAPR provided by the embodiment of the present invention is adopted. When the value is 0, the method for reducing PAPR provided by the embodiment of the present invention is not used. In addition, it is also possible to multiplex a certain bit in the signaling field/service field, that is, to use a certain existing bit to indicate whether to adopt the method for reducing PAPR provided by the embodiment of the present invention.
  • the signaling field/service field needs to be modified, and the specific method may add 2 bits in the field.
  • the bit is the first value, the PTS technology provided by the embodiment of the present invention is not used.
  • the bit is the second value, the method for reducing PAPR provided by the embodiment of the present invention is used, and the number of blocks is 2,
  • the method for reducing PAPR provided by the embodiment of the present invention is used, and the number of blocks is 4.
  • the number of blocks is 4.
  • the method and the number of partitions is 2.
  • the phase factor of the transmission dependent channel is taken as an example of the reserved subcarrier, that is, the phase factor used to reduce the peak-to-average ratio is transmitted by using some subcarriers in the OFDM symbol for reducing the peak-to-average ratio.
  • the use of reserved subcarriers may be further extended to utilize a particular subcarrier, for example, the pilot subcarriers in 802.11ad may also be performed in accordance with methods of embodiments of the present invention.
  • the present invention can be extended to OFDM and OFDMA systems. For a single-user OFDM system, a pilot subcarrier can be used to transmit a phase factor. For a multi-user OFDMA system, a reserved subcarrier can be used to transmit a phase factor.
  • a method for reducing a peak-to-average ratio provided by the present invention includes:
  • Subcarriers carrying OFDM symbols carrying data to be transmitted are divided to obtain a plurality of partitions
  • Each of the plurality of partitions is multiplied by a corresponding phase factor and transmitted.
  • multiplying each of the plurality of partitions by a corresponding phase factor is a process of reducing PAPR for a plurality of partitions (or the OFDM symbols), specifically, each bearer in each partition
  • the subcarrier of the transmitted data is multiplied by the phase factor corresponding to the block and then transmitted.
  • the specific subcarrier is a reserved subcarrier, wherein the reserved subcarrier is a subcarrier reserved in a subcarrier of the OFDM symbol; wherein the reserved subcarrier carries phase factor information, and thus the transmission does not need to be multiplied by a phase factor.
  • the reserved subcarriers there are at least two ways to use the reserved subcarriers to transmit the phase factor: the first is to directly transmit the phase factor, that is, directly carry the phase factor on the reserved subcarrier. The transmission is performed on the wave; the second is to convert the phase factor into phase factor information and then transmit, wherein the phase factor information can be encoded, modulated or repeated.
  • the specific subcarrier is a pilot subcarrier; further, transmitting the multiple phase factors by using the specific subcarrier of the OFDM symbol includes: carrying multiple phase factors on the pilot subcarrier for transmission, where The frequency subcarrier carries the product of the corresponding phase factor and the pilot signal of the plurality of phase factors. It should be understood that when the phase factor is transmitted by using the pilot subcarrier, the phase factor is not required to be converted and modulated, but the pilot signal is directly multiplied by the phase factor to be transmitted on the pilot subcarrier, and then carried. The transmission is performed on pilot subcarriers, wherein some or all of the pilot subcarriers may be used for transmission.
  • the specific subcarriers may be one or more, and specifically, the reserved subcarriers or pilot subcarriers may be one or more. Specifically, it is necessary to use some or all of the specific subcarriers (that is, which specific subcarriers or the number of specific subcarriers are specifically selected) to transmit the phase factor, which can be flexibly determined according to the transmission reliability or the actual requirement, and only examples are given below.
  • the embodiment of the invention is not limited.
  • the specific subcarriers with specific subcarrier numbers in the embodiments of the present invention are only exemplary, and the specific subcarriers are not limited to specific subcarriers, and may be determined according to actual conditions in actual application, or according to standards.
  • the location determination of the reserved subcarriers or pilot subcarriers is within the scope of the present invention as long as the method of the embodiments of the present invention is applied to a specific subcarrier.
  • the QPSK, the QAM, and the like in the embodiments of the present invention are only examples of the modulation mode, and the specific modulation mode may also be phase shift keying modulation, differential modulation, energy modulation, or other common modulation modes.
  • the block coding, the BCH coding, and the like in the embodiment of the present invention are only examples of the coding mode.
  • the specific coding mode may also be RS coding, cyclic coding, convolutional coding, Reed-Muller coding, or other common coding modes. The embodiment is not limited.
  • FIG. 9 is a schematic diagram of a principle of transmitting phase factor information in a WiFi system, as shown in FIG.
  • Step 901 Divide data transmitted by one orthogonal frequency division multiplexing OFDM symbol into Q blocks, where each block has a phase factor corresponding thereto, and each phase factor is represented by q bits;
  • phase factor minimizes a PAPR of the OFDM symbol
  • a part of subcarriers are reserved on the OFDM symbol, that is, reserved subcarriers; for OFDM a block on a subcarrier on a symbol, determining a phase factor of each block, and multiplying data carried on each block by a corresponding phase factor when transmitting the signal, to reduce a peak-to-average ratio of the OFDM symbol;
  • the subcarrier is reserved for transmitting the phase factor; the phase factor information is carried on the reserved subcarrier, and thus does not need to be multiplied by the phase factor;
  • each block has a phase factor corresponding thereto, and each phase factor is represented by q bits, that is, Q phase factor(s) are converted into phase factor information for use with reserved subcarriers. transmission. Further, the conversion is performed according to a mapping rule between the phase factor and the phase factor information; wherein the mapping rule includes a table mapping, a formula mapping, and the like.
  • the OFDM symbol of the 1024 subcarriers of the 80M bandwidth shown in FIG. 4 is divided into 4 blocks in the frequency domain, and 256 subcarriers (corresponding to 20M bandwidth) are used as a block, wherein each block has a phase corresponding thereto.
  • Factor a total of 4 phase factors, each phase factor is represented by 2 bits, and the 2 bits are phase factor information corresponding to each block, then a total of 8 bits need to be transmitted, and the 8 bits are phase factor information of the OFDM symbol .
  • each block is multiplied by a corresponding phase factor, and transmitted by using OFDM subcarriers, which is equivalent to dividing the OFDM symbols into M blocks in the frequency domain. Multiply by the corresponding phase factor.
  • the following steps may be separately performed for each of the Q blocks, such that the reserved subcarriers in each transport block transmit the phase factor of the transport block, and of course, the Q phase factors of the Q transport blocks may also be used.
  • Uniformly use some or all of the reserved subcarriers for transmission. The following is an example of the latter. Therefore, data such as Q and q are used. When the former is used as an example, the corresponding Q and q and other data are replaced by one transmission. The corresponding data in the block can be omitted, and will not be described here.
  • Step 902 Encoding Q*q bits representing Q phase factors to obtain encoded k bits
  • Q*q bits representing Q phase factors are phase factor information
  • the coding mode may select a coding mode such as a block coding code, a CRC code, or a parity check code. For example, if the phase factor information of the 8 bits to be transmitted is encoded by (16, 8) blocks, 16 bits of the encoded data need to be transmitted;
  • the generation matrix of the block coding may be:
  • phase factor information may increase the transmission reliability, but the following steps may be performed without coding, which may be flexibly determined according to actual needs.
  • Step 903 Modulate the encoded k bits to obtain K symbols.
  • the modulation mode may adopt direct modulation, such as direct QPSK modulation, or energy modulation of transmission mode 2, such as non-transmission of signals on subcarriers corresponding to bit 0, and transmission of a fixed value pilot signal on subcarriers corresponding to bit 1. It is also possible to use differential modulation of transmission mode 3, such as DQPSK modulation.
  • DQPSK modulation is applied to the encoded 16-bit data to obtain 8 symbols;
  • Or energy modulation is applied to the encoded 16-bit data (a signal is not transmitted on a subcarrier corresponding to bit 0, and a pilot signal of a fixed value is transmitted on a subcarrier corresponding to bit 1) to obtain 16 symbols.
  • Step 904 Repeating the modulated K symbols by p times to obtain K*p symbols, and then mapping the repeated K*p symbols onto the reserved subcarriers of the OFDM symbol for transmission;
  • repeating the modulated symbols may increase transmission reliability, but subcarrier mapping may also be performed without repetition, which may be flexibly determined according to actual needs.
  • Step 905 Map the modulated K symbols or the repeated K*p symbols onto the reserved subcarriers of the OFDM symbol for transmission.
  • mapping K or K*p symbols onto the reserved subcarriers of OFDM first of all, it should be ensured that the reserved subcarriers are dispersed as much as possible in the frequency band, and then the symbols to be transmitted are mapped as possible to some or all of the reserved sub-distributors. Transmission on the carrier. For example: 80M bandwidth, 1024 subcarrier OFDM symbols, there are 24 reserved subcarriers, evenly dispersed throughout the frequency band, or as much as possible to ensure this There are certain carrier intervals between the reserved subcarriers; when there are 24 symbols or less to be transmitted, the mapping may be performed according to the rule with the smallest variance of the sequence numbers difference between adjacent reserved subcarriers, and then transmitted.
  • the reserved subcarrier used for transmitting information when using differential modulation is independent of the allocated subband, and does not rely on channel information when receiving, for example, the symbol modulated by DQPSK can be recovered without relying on channel information when receiving; using energy modulation When the transmitted signal is recovered according to the energy signal, the channel information is not required to be trusted; when QPSK modulation is used, each reserved subcarrier for transmitting the phase factor information is combined with one subband, and the channel in the subband can be used for receiving. Information, channel information is required for recovery upon reception.
  • the number of symbols after the repetition is less than or equal to the number of reserved subcarriers, but the symbol using the non-differential modulation is recovered by the channel information, so the differential modulation in the transmission fee is used.
  • the reserved subcarrier of the symbol is to be adjacent to the subband of the transmitted data.
  • each transport block (here, one transport block corresponds to 20M bandwidth, 256 subcarriers, as described above) is reliably transmitted by using these 24 subcarriers to reduce the peak-to-average ratio.
  • each transport block (here, one transport block corresponds to 20M bandwidth, 256 subcarriers, as described above) is reliably transmitted by using these 24 subcarriers to reduce the peak-to-average ratio.
  • the basic idea is the same when the implementation scheme and 26 subcarriers are one subband, but because the number of subbands (19) of this scheme is smaller than the number of reserved subcarriers (24), when using non-differential modulation, the number of repetitions is affected. The number of sub-bands (19) is different, so the specific design is different.
  • FIG. 10 is a schematic diagram of a specific implementation manner of several transmission phase factor information, as shown in FIG. 10, where the implementation manner 1001, the implementation manner 1002, and the implementation manner 1003 adopt the first blocking manner mentioned above, that is, 26
  • the subcarriers are divided into one subband. In the case of 80M bandwidth and 1024 subcarriers, 38 subbands are obtained, and 24 subcarriers are reserved. The distribution rule of the reserved subcarriers is determined according to the needs of subcarrier mapping.
  • the implementation manner 1004, the implementation manner 1005, and the implementation manner 1006 adopt the second blocking method mentioned above, that is, divide 52 subcarriers into one subband, and divide the subband with 80M bandwidth and 1024 subcarriers to obtain 19 subbands. , 24 reserved subcarriers, reserved The distribution law of subcarriers is determined according to the needs of subcarrier mapping.
  • Figure 10a is a schematic diagram showing the distribution of reserved subcarriers in the frequency domain. As shown in Fig. 10a, the longer arrow indicates 0 intermediate frequency, the rectangle indicates subband, the shorter arrow indicates reserved subcarrier, and there is one reserved subcarrier between the two subbands.
  • three mapping modes are provided. When performing subcarrier mapping, the selection may be based on a rule with the smallest variance of the sequence number difference between adjacent reserved subcarriers.
  • FIG. 10a only provides the reserved subcarrier distribution.
  • the number of specific subcarriers or subbands is not limited.
  • the subbands and adjacent reserved subcarriers form a repeating structure. The number of repeating structures should be based on actual conditions. The specific implementation should be appropriate according to actual needs. Adjustments are not limited in this embodiment of the present invention.
  • FIG. 10 the six specific implementation manners in FIG. 10 are exemplified by an 80 M bandwidth and 1024 subcarriers, which are divided into four transport blocks, and need to transmit 8-bit phase factor information.
  • the 8-bit phase factor information is encoded by (16, 8) blocks to obtain 16-bit data, and the 16-bit data is DQPSK-modulated to obtain 8 symbols, and the modulated 8 symbols are repeated 3 times. Obtaining 24 symbols and then mapping the 24 symbols onto 24 reserved subcarriers.
  • One possible distribution rule for these 24 reserved subcarriers is: (188 215 242 269 296 323 350 377 404 431 458 485 539 566 593 620 647 674 701 728 755 782 809 836), this way is to keep the subcarriers concentrated near the center of the band, as in the distribution mode 1001a in Figure 10a; another possible distribution rule for these 24 reserved subcarriers It is: (32 59 86 113 140 167 194 221 248 275 302 329 991 964 937 910 883 856 829 802 775 748 721 694), this way is to keep the subcarriers concentrated near the edge of the band, as shown in Figure 10a Method 1002a.
  • the sequence numbers of the subcarriers are from 0 to 1023 in the order of arrangement.
  • the 8-bit phase factor information is encoded by (16, 8) blocks to obtain 16-bit data, the 16-bit data is QPSK-modulated to obtain 8 symbols, and the modulated 8 symbols are repeated 3 times. Obtaining 24 symbols and then mapping the 24 symbols onto 24 reserved subcarriers.
  • One possible distribution rule for these 24 reserved subcarriers is: (188 215 242 269 296 323 350 377 404 431 458 485 539 566 593 620 647 674 701 728 755 782 809 836), this way is to keep the subcarriers concentrated near the center of the band, as in the distribution mode 1001a in Figure 10a; another possible distribution rule for these 24 reserved subcarriers It is: (32 59 86 113 140 167 194 221 248 275 302 329 991 964 937 910 883 856 829 802 775 748 721 694), this way is to keep the subcarriers concentrated near the edge of the band, as shown in Figure 10a Method 1002a.
  • the sequence numbers of the subcarriers are from 0 to 1023 in the order of arrangement.
  • the 8-bit phase factor information is encoded by (16, 8) blocks to obtain 16-bit data, and the 16-bit data is energy-modulated to obtain 16 symbols. Since only 24 reserved subcarriers are used, The 16 symbols are all repeatedly mapped to the reserved subcarriers. Therefore, the embodiment of the present invention is not repeated in the implementation 1003. Of course, some of the 16 symbols after modulation may be repeated to fully utilize the 24 reserved subcarriers. The embodiment of the invention is not limited thereto. Mapping the modulated 16 symbols onto 16 reserved subcarriers of the 24 reserved subcarriers.
  • One possible distribution rule for the 16 reserved subcarriers is: (296 323 350 377 404 431 458 485 539 566 593 620 647 674 701 728), this way is to keep the subcarriers concentrated near the center of the band, as in the distribution mode 1001a in Figure 10a; another possible distribution rule for these 24 reserved subcarriers is: (32 59 86 113 140 167 194 221 883 856 829 802 775 748 721 694), this way is to keep the subcarriers concentrated near the edge of the band, as shown in the distribution mode 1002a in Figure 10a.
  • the sequence numbers of the subcarriers are from 0 to 1023 in the order of arrangement.
  • the 8-bit phase factor information is encoded by (16, 8) blocks to obtain 16-bit data, the 16-bit data is DQPSK-modulated to obtain 8 symbols, and the modulated 8 symbols are repeated 3 times. Obtaining 24 symbols and then mapping the 24 symbols onto 24 reserved subcarriers.
  • One possible distribution rule for these 24 reserved subcarriers is: (5 6 7 60 113 166 219 272 325 378 431 484 538 591 644 697 750 803 856 909 962 1015 1016 1017), wherein, with 52 subcarriers as one subband, only 19 subbands and 24 reserved subcarriers are allocated 5, 6, 7, and 1015, 1016, 1017 is reserved for subcarriers (0th to 5th subcarriers, and 1018th to 1023th subcarriers are protection subcarriers, no data is transmitted), and the remaining reserved subcarriers are inserted between two data block subbands.
  • the carrier which is exactly 18 reserved subcarriers (note that the 512th subcarrier is 0 IF does not transmit data), as in the distribution mode 1003a in Fig. 10a.
  • the 8-bit phase factor information is encoded by (16, 8) blocks to obtain 16-bit data, and the 16-bit data is QPSK-modulated to obtain 8 symbols, and the modulated 8 symbols are repeated twice.
  • Get 16 symbols then map the 16 symbols onto 16 reserved subcarriers of the 24 reserved subcarriers, which is different from implementation 1002, since there are only 19 subbands, and the QPSK modulated symbols are recovered. It is necessary to use channel information, which needs to keep the subcarriers and subbands adjacent, so the number of symbols in the mapping is less than or equal to the number of subbands, so at most 16 reserved subcarriers (or less than or equal to 19 retainers) can be used. Carrier) for transmission.
  • One possible distribution rule for these 16 reserved subcarriers is: (88 141 194 247 300 353 406 459 565 618 671 724 777 830 883 936), which keeps the subcarriers concentrated near the center of the band, such as The distribution pattern 1001a in Figure 10a; another possible distribution rule for these 24 reserved subcarriers is: (57 110 163 216 269 322 375 428 646 699 752 805 858 911 964 1017), which is to preserve the subcarriers Focusing on the position near the edge of the band, as in the distribution mode 1002a in Figure 10a.
  • the sequence numbers of the subcarriers are from 0 to 1023 in the order of arrangement.
  • 8-bit phase factor information is encoded by (16,8) blocks to obtain 16-bit data
  • 16-bit data is energy-modulated to obtain 16 symbols because only 24 reserved subcarriers and 19 sub-bands are obtained. Therefore, the 16 symbols cannot be repeatedly mapped to the reserved subcarriers. Therefore, the embodiment of the present invention is not repeated in the implementation 1003. Of course, some of the 16 symbols after modulation may be repeated to make full use of 24 symbols.
  • the subcarriers are reserved, which is not limited in this embodiment of the present invention.
  • the modulated 16 symbols are mapped onto 16 reserved subcarriers of the 24 reserved subcarriers.
  • One possible distribution rule of the 16 reserved subcarriers is: (88 141 194 247 300 353 406 459 565 618 671 724 777 830 883 936), this way is to keep the subcarriers concentrated near the center of the band, as in the distribution mode 1001a in Figure 10a; another possible distribution rule for these 24 reserved subcarriers is: (57 110 163 216 269 322 375 428 646 699 752 805 858 911 964 1017), this way is to keep the subcarriers concentrated near the edge of the band, as in the distribution mode 1002a in Figure 10a.
  • the sequence numbers of the subcarriers are from 0 to 1023 in the order of arrangement.
  • the embodiment of the present invention specifically provides the following processing:
  • FIG. 10b is a schematic diagram of a division manner of 1024 subcarriers in 802.11ax. As shown in FIG. 10b, the entire 1024 subcarriers are divided into four blocks, namely, block 1, block 2, block 3, and block 4, and each block has several subbands. And retaining subcarriers, using 26 subcarriers as one subband, dividing the 80M bandwidth into 1024 subcarriers, a total of 37 subbands, and 32 reserved subcarriers are not used, as follows:
  • subcarriers are used to protect subcarriers, 13 on the left and 12 on the right;
  • the middle 5DC represents five intermediate frequencies (or collectively referred to as 0 intermediate frequency), and 5 intermediate frequencies do not transmit data.
  • the subcarrier numbers are 0, -1, 1, 2, 3;
  • each 13 sub-carriers located on both sides of the 0 intermediate frequency form a sub-band
  • Two reserved subcarriers, a total of 32 subcarriers, and the specific distribution position (or subcarrier number) is (-498, -497, -444, -443, -390, -389, -336, -335, - 256,-255,-202,-201,-148,-147,-94,-93,95,96,149,150,203,204,257,258,337,338,391,392,445,446 , 499, 500), the subcarrier number is from -511 to 512.
  • the PTS method can be used in the system to reduce the peak-to-average ratio.
  • the method described above is applied, and several design schemes are as follows.
  • the above 1024 subcarriers can be divided into 2 blocks or 4 blocks. When the above 1024 subcarriers are divided into two blocks, they may be specifically divided into: block 1 is a subcarrier -511 to 0; and block 2 is a subcarrier 1 to 512.
  • the above 1024 subcarriers are divided into 4 blocks, specifically: block 1 is a subcarrier -511 to -257; block 2 is a subcarrier -256 to 0; block 3 is a subcarrier 1 to 258; and block 4 is a subcarrier 259 to 512 ;
  • the above division ensures that there are 8 reserved subcarriers in each partition.
  • each of the 4 blocks the corresponding phase factor is Taking the first block as an example, there are two options: select (-498, -497, -444, -443, -390, -389, -336, -336) to transmit on 8 subcarriers. Or select 4 of them to transmit, in which case each of each pair of subcarriers is selected, such as (-498, -444,, -390, -336, -335) transmission
  • the transmission of other blocks is similar, and can be obtained by referring to the processing manner of the first block, and details are not described herein again.
  • differential modulation is performed between the same subcarriers of two adjacent symbols, as follows:
  • known pilot information is transmitted on all reserved subcarriers, such as ⁇ 0 ;
  • the corresponding phase factor on the nth symbol of a block is The corresponding phase information on the reserved subcarrier is ⁇ n , then
  • the first OFDM symbol used for differential modulation may select the last one of the STF or LTF; or the first OFDM symbol is not subjected to the PAPR reduction process, and the pilot signals transmitted on all the reserved subcarriers are all 1 or have been The signal is known as the first OFDM symbol used for differential modulation.
  • All 32 reserved subcarriers can be selected, or some of them can be selected.
  • each of the pair of subcarriers is selected, such as (-498, -444, -390, -336, -335) to transmit ⁇ n .
  • ⁇ n may be the optimal phase obtained according to the corresponding algorithm, or may be the two-bit information obtained according to Table 1 in Scheme 2, and then the result of QPSK modulation based on the two bits.
  • differential modulation is performed between adjacent two carriers of the same symbol, as follows:
  • the corresponding phase of the block m is ⁇ m , corresponding to the corresponding phase factor on the nth symbol Transmitting known pilot information p on the kth subcarrier and transmitting known pilot information on the k+1th subcarrier Taking the first block as an example, transmitting p on the four subcarriers (-498, -444, -390, -336), and transmitting at (-497, -443, -389, -335) .
  • ⁇ m may be the optimal phase obtained according to the corresponding algorithm, or may be the two-bit information obtained according to Table 1 in Scheme 2, and then QPSK-modulated modulation symbols according to the two bits.
  • the first OFDM symbol used for differential modulation may select the last one of the STF or LTF; or the first OFDM symbol is not subjected to the PAPR reduction process, and the pilot signals transmitted on all the reserved subcarriers are all 1 or have been The signal is known as the first OFDM symbol used for differential modulation.
  • the differential modulation + coding method is used to transmit the phase factor.
  • an indication needs to be added in the control signaling to notify the receiving end whether the peak-to-peak ratio processing method mentioned in the present invention is adopted in the transmission symbol;
  • phase factor information 8 bits is encoded, and the encoded data is 16 bits, specifically, (16, 8) block coding, 1/2 bite-tailed convolutional code, etc.;
  • 3 pairs of sub-carriers in each block take 3 pairs, such as the first block selection (-498, -497, -444, -443, -390, The six subcarriers of (-498, -497, -444, -443, -390, -389) in -389, -336, -336).
  • the method of QAM modulation + coding (specifically, the implementation scheme is to adopt QPSK) is used to transmit phase shift information.
  • an indication needs to be added in the control signaling to notify the receiving end whether or not the present invention is used in the transmission symbol.
  • the peak drop ratio is the same as the treatment method;
  • phase factor information 8 bits is encoded, and the encoded data is 16 bits, specifically, (16, 8) block coding, 1/2 bite-tailed convolutional code, etc.;
  • 3 pairs of sub-carriers in each block take 3 pairs, such as the first block selection (-498, -497, -444, -443, -390, The six subcarriers of (-498, -497, -444, -443, -390, -389) in -389, -336, -336).
  • the method of energy modulation + coding (specifically, the implementation scheme is to adopt QPSK) is used to transmit the phase shift information.
  • an indication needs to be added in the control signaling to notify the receiving end whether or not the present invention is used in the transmission symbol.
  • the peak drop ratio is the same as the treatment method;
  • phase factor information 8 bits is encoded, and the encoded data is 16 bits, specifically, (16, 8) block coding, 1/2 bite-tailed convolutional code, etc.;
  • the symbols after modulation are transmitted with all 32 reserved subcarriers.
  • pilot subcarriers in each subband or resource block, and the pilot subcarriers do not carry data to be transmitted during specific transmission, and therefore, when implementing the method provided by the embodiment of the present invention, When the data carried by the block is multiplied by the corresponding phase factor of the block, the pilot subcarriers (or pilot signals carried therein) in the block need not be multiplied by a phase factor.
  • the input data in the OFDM symbol is x(n)
  • the data after PTS transformation is y(n)
  • n 0, 1, 2, . . . , N-1, where n is the sequence number of the subcarrier.
  • N is the number of subcarriers.
  • n is not the pilot subcarrier number, the following operations are performed:
  • the subcarrier corresponding to n is not a reserved subcarrier or a pilot subcarrier
  • phase factor 1, 2, 3, 4, ⁇ m from the set Value in the middle, that is From the collection
  • the value is taken to minimize the PAPR of the OFDM symbol that outputs the output data.
  • G 8*16 can be the matrix described below
  • a BCH (Bose-Chauduri-Hocquenghem) code (15, 11) may be used, where the information bit length to be input is 11 and the coded code length is 15 bits.
  • the coded code length is 15 bits.
  • the processing at this time is: b 0 b 1 b 2 b 3 b 4 b 5 b 6 b 7 is padded with 3 0s and expanded to 11 Bit, obtain b 0 b 1 b 2 b 3 b 4 b 5 b 6 b 7 000, perform BCH coding of (15, 11) on the 11 bits, and obtain the output bit after encoding [b' 0 b' 1 b' 2 ...b' 14 b' 15 ], where b' 15 is the padded zero value (ie supplemental redundant bit 0).
  • QPSK modulation is performed on b' 0 b' 1 b' 2 ... b' 15 , and the modulated data is y s, 0 , y s, 1 , y s, 2 , y s, 3 , y s, 4 , y s,5 ,y s,6 ,y s,7 , where s is the sequence number of the OFDM symbol.
  • G 8*16 can be the matrix described below
  • QPSK modulation is performed on b' 0 b' 1 b' 2 ... b' 31 , and the modulated data is y s, 0 , y s, 1 , y s, 2 , y s, 3 , y s, 4 , y s,5 , y s,6 ,...y s,15 , where s is the sequence number of the OFDM symbol.
  • the embodiment of the present invention uses a reserved subcarrier in an OFDM symbol to transmit a phase factor for reducing a PAPR (of an OFDM symbol), wherein the phase factor is obtained according to the PTS method provided by the embodiment of the present invention, and then The phase factor is transmitted using reserved subcarriers. Specifically, the phase factor is converted into phase factor information according to the corresponding rule, and then the phase factor information is encoded, modulated, or repeated, and then mapped to the reserved subcarrier for transmission.
  • 802.11ad is a subsystem in the IEEE 802.11 (or WLAN, WLAN) system. It works in the 60 GHz high frequency band and is mainly used to realize the transmission of wireless HD audio and video signals in the home, which brings more complete functions for home multimedia applications.
  • HD video solution also known as WiGig (60GHz Wi-Fi).
  • WiGig 60GHz Wi-Fi
  • 802.11ad technology has high capacity and high rate in multimedia applications (the highest transmission rate can reach 7Gbps when PHY adopts OFDM multi-carrier scheme, and the maximum transmission rate can reach 4.6Gbps when single-carrier modulation scheme is used), Low latency, low power consumption and more.
  • Figure 11a shows the PAPR CCDF distribution simulation of the 802.11ad system.
  • 802.11ad since 802.11ad operates in the high frequency range of 60 GHz, it is more sensitive to the PAPR problem because the amplifier with large dynamic range is very expensive in the high frequency band.
  • the cost of the required amplifier limits the application of the 802.11ad system.
  • the PAPR problem of the OFDM system causes the system to adopt a costly amplifier, thereby limiting the application of the 11ad system.
  • the PTS algorithm can also be used for 802.11ad to reduce the PAPR.
  • the present invention provides a method for multiplexing pilot subcarriers to use the PTS algorithm, thereby effectively solving the PAPR problem.
  • one OFDM symbol is composed of 512 subcarriers (for example, an OFDM symbol in an 802.11ad system), and the peak-to-average ratio can also be reduced by the method provided by the embodiment of the present invention.
  • the use of the pilot subcarriers to transmit the phase factor of the current OFDM symbol is also used, in contrast to the above-mentioned reserved subcarriers for transmitting the current OFDM symbol with the reserved subcarriers. That is to say, the pilot subcarrier can be used not only to transmit the pilot signal but also to transmit the phase factor.
  • the specific process is as follows:
  • the number of 512 subcarriers of an OFDM symbol is numbered from -255 to 256, namely -255, -254, -253, ..., -1, 0, 1, 2, ..., 255, 256; such subcarriers with sequence number 0 It is just 0 IF.
  • the 512 subcarriers of one OFDM symbol are divided as follows:
  • Subcarriers numbered (-150, -130, -110, -90, -70, -50, -30, -10, 10, 30, 50, 70, 90, 110, 130, 150) are used to transmit pilot signals;
  • the subcarrier with sequence number (0, +1, -1) does not transmit any signal
  • No signal is transmitted on subcarriers with a sequence number greater than 177 or less than -177;
  • the remaining 336 subcarriers are used to transmit data symbols.
  • the 512 subcarriers of the foregoing OFDM symbol may be divided into several blocks, for example, divided into 2 or 4 blocks, and data and pilots carried on each subcarrier are multiplied by a phase factor corresponding to the block, and a phase may be selected for each block.
  • the factor is such that the PAPR of the OFDM symbol is minimized, wherein the phase factor can be determined using two typical algorithms provided above.
  • the specific blocking method is as follows:
  • the corresponding subcarrier number of the first block is -255 to 0; the corresponding subcarrier number of the second block is 1 to 256;
  • the corresponding subcarrier number of the first block is -255 to -90; the subcarrier number corresponding to the second block is -89 to 0; the corresponding subcarrier number of the third block is 1 to 89; the corresponding subcarrier number of the fourth block is from 90 to 256.
  • T s is the sampling time
  • q is the sampling number
  • N SYM is the number of OFDM symbols to be transmitted
  • T SYM is the length of the slot corresponding to the OFDM symbol
  • T GI is the time corresponding to the guard interval
  • D k,n is the transmitted data
  • p n+1 P k is the pilot signal
  • exp(j ⁇ 1 ) exp(j ⁇ 2 ) is the phase factor introduced by reducing PAPR
  • N SR 177.
  • T s is the sampling time
  • q is the sampling number
  • N SYM is the number of OFDM symbols to be transmitted
  • T SYM is the length of the slot corresponding to the OFDM symbol
  • T GI is the time corresponding to the guard interval
  • D k,n is the transmitted data
  • p n+1 P k is the pilot signal
  • exp(j ⁇ 1 ), exp(j ⁇ 2 ), exp(j ⁇ 3 ), exp(j ⁇ 4 ) is the PAPR reduction.
  • N SR 177.
  • the phase factor in the above-mentioned transmitted signal may be set to 1, thereby being compatible with the existing standard.
  • phase factor selection is not limited, and may be selected from a fixed set, or any value obtained by other methods may be used.
  • the receiver needs to make some adjustments.
  • the pilot subcarrier is used to obtain the phase deviation, and the phase deviation can be reflected by the phase deviation factor.
  • the general algorithm is as follows.
  • the signal received on the kth subcarrier is:
  • k is the sequence number of the pilot subcarrier ⁇ -150, -130, -110, -90, -70, -50, -30, -10, 10, 30, 50, 70, 90, 110, 130, 150 ⁇
  • z k is noise
  • h k is a known channel
  • e j ⁇ is a phase deviation factor
  • r k is a received signal.
  • phase deviation factor is obtained as follows:
  • ⁇ is the set of sequence numbers of the pilot subcarriers ⁇ -150, -130, -110, -90, -70, -50, -30, -10, 10, 30, 50, 70, 90, 110, 130, 150 ⁇ .
  • Channel compensation is performed on the received signal by using the compensated channel information.
  • the phase offset factor and phase factor of the first block are obtained using the pilot subcarriers ⁇ -150, -130, -110, -90, -70, -50, -30, -10 ⁇ .
  • Product, where the received signal is:
  • ⁇ 1 ⁇ -150, -130, -110, -90, -70, -50, -30, -10 ⁇ .
  • Channel compensation is performed on the received signal on the first block by using the compensated channel information.
  • the phase offset factor and phase of the second block obtained using the pilot subcarriers ⁇ -150, -130, -110, -90, -70, -50, -30, -10 ⁇
  • the product of the factors, where the received signal is:
  • Channel compensation is performed on the received signal on the second block by using the compensated channel information.
  • the estimation of the phase deviation based on the pilot subcarriers is also adjusted according to the condition of the blocking.
  • the estimation of the phase deviation and phase compensation (corresponding to the phase deviation, which is the conjugate or the opposite of the phase deviation) is adjusted as follows:
  • the phase offset can be estimated based on the pilot subcarriers (-150, -130, -110, -90) obtained by channel response;
  • the estimation of the phase offset can be obtained according to the channel response of the pilot subcarriers (-70, -50, -30, -10);
  • the estimation of the phase offset can be obtained from the channel response of the pilot subcarriers (10, 30, 50, 70);
  • the estimate of the phase offset can be derived from the channel response of the pilot subcarriers (90, 110, 130, 150).
  • 2 bits are reserved in the OFDM frame header field to indicate whether the method provided by the embodiment of the present invention is applied, or to indicate which method is used, as follows:
  • the OFDM symbol received by the receiving end of the 802.11ad is the same as the existing OFDM symbol; or the method for reducing the PAPR provided by the embodiment of the present invention is not used;
  • FIG. 11 is a schematic diagram of a reduced PAPR according to an embodiment of the present invention. As shown in FIG. 11, the method provided by the embodiment of the present invention is applied to a directional multiple multi-gigabit (DMG) OFDM. The parameters and results are shown in Table 2:
  • DMG directional multiple multi-gigabit
  • the selected set of phase factors in Table 2 indicates that when determining the phase factor, a set of phase factors can be selected therefrom, for example: ⁇ 1, j, -1, -j ⁇ , corresponding to the typical algorithm 2 provided above.
  • the method provided by the embodiment of the present invention can activate a larger PAPR gain with less adjustment or modification.
  • the receiver can recover the original signal.
  • the application of the PTS method in the WiFi system is made possible, thereby effectively reducing the PAPR of the data.
  • the present invention also provides a method for reducing the peak-to-average ratio when used in multiple antennas. Also taking 802.11ax as an example, it is necessary to support 1 to 8 antennas for 80M bandwidth.
  • the 80M bandwidth is divided into 1024 subcarriers, and there are 37 subbands, and 32 reserved subcarriers are not used.
  • the specific subcarrier division is as shown in FIG. 10b:
  • subcarriers are used to protect subcarriers, 13 on the left and 12 on the right;
  • each 13 sub-carriers located on both sides of the 0 intermediate frequency form a sub-band
  • the subcarriers have a sequence number from -511 to 512.
  • the channel information corresponding to the reserved subcarrier is known, and the processing manner is as follows:
  • Each stream is separately subjected to peak-to-peak ratio processing, and a phase factor transmitted on each reserved subcarrier is obtained and transmitted, wherein all streams use the same reserved subcarrier to transmit a phase factor;
  • Subsequent operations are as a single stream (or as in the case of one OFDM symbol above).
  • the transmitting end has two antennas for signal transmission
  • the receiving end has two antennas for receiving
  • two streams respectively transmit OFDM symbols
  • the subcarriers on the OFDM symbols on the two streams are divided into four blocks.
  • the phase factor corresponding to the first stream is
  • the phase factor corresponding to the second stream is
  • ⁇ 11 represents the phase of the first stream on the first partition
  • ⁇ 21 represents the phase of the second stream on the first partition.
  • the four subcarriers (-498, -444, -390, -336) on the first partition are also taken to transmit the two phase factors simultaneously.
  • the received signal can be expressed as:
  • the existing MIMO processing method can be used to solve the estimation of the phase factor transmitted on the -498 subcarrier.
  • an estimate of the two phase factors transmitted on the (-444, -390, -336) subcarriers can be found.
  • the phase factor information can be recovered substantially without errors.
  • the processing of the remaining 3 blocks is similar.
  • the reserved subcarrier transmits information of the phase factor itself, and the reserved subcarrier transmission may also be information after modulating the phase factor (such as QPSK), differentially modulating the phase factor, and phase factor.
  • Information after energy modulation information that encodes and modulates the phase factor, information that encodes and differentially modulates the phase factor, or information that encodes and modulates the phase factor, and the like.
  • Each stream is separately subjected to peak-to-peak ratio processing to obtain a phase factor transmitted on each reserved subcarrier;
  • Each stream is assigned a set of reserved subcarrier transmission phase factors, where a total is shared in each partition Four pairs of reserved subcarriers, wherein a group of reserved subcarriers means that one of the four pairs of reserved subcarriers is selected as a group of four subcarriers, and the other four subcarriers are grouped, and the other segments are similar, for example, Group subcarriers (-498, -444, -390, -336) and another set of subcarriers (-497, -443, -389, -335);
  • Subsequent operations are as a single stream (or as in the case of one OFDM symbol above).
  • each stream allocates a different reserved subcarrier transmission phase factor.
  • the transmitting end has two antennas for signal transmission
  • the receiving end has two antennas for receiving
  • two streams respectively transmit OFDM symbols, wherein the subcarriers on the OFDM symbols on the two streams are divided into four blocks.
  • the phase factor corresponding to the first stream is
  • the phase factor corresponding to the second stream is Where ⁇ 11 represents the phase of the first stream on the first partition and ⁇ 21 represents the phase of the second stream on the first partition.
  • the transmission modes 1, 2, 3, etc., and the information after the phase factor is modulated may be transmitted by directly transmitting the phase factor, and the transmission is differentiated from the phase factor.
  • the modulated information the information obtained by transmitting the phase factor for energy modulation, transmitting the information encoding and modulating the phase factor, transmitting the information for encoding and differentially modulating the phase factor, and transmitting the information for encoding and modulating the phase factor .
  • All the streams are jointly processed by the peak-down ratio, and the phase factor information transmitted on each reserved sub-carrier is obtained;
  • Subsequent operations are as a single stream (or as in the case of one OFDM symbol above).
  • phase factor information there are two streams sent at the transmitting end as an example.
  • the subcarriers on the OFDM symbol are still divided into four blocks, and the corresponding phase factor of each block is with .
  • the determined four phase factors are such that the peak-to-average ratio of the two OFDM symbols transmitted by the two streams is the smallest (or the sum of the two peak-to-average ratios is the smallest).
  • the four reserved subcarriers (-498, -444, -390, -336) on the first block are taken to simultaneously transmit the phase factor information corresponding to the first stream, and the two streams transmit the same on the four subcarriers. Phase factor information.
  • the phase factor information transmitted includes the following methods: direct transmission of the phase factor, transmission of information after modulation of the phase factor (such as QPSK), transmission of information after differential modulation of the phase factor, and transmission of phase factors for energy modulation. And transmitting information that encodes and modulates the phase factor, transmits information that encodes and differentially modulates the phase factor, or transmits information that encodes and modulates the phase factor, and so on.
  • the embodiment of the present invention further provides a device for reducing a peak-to-average ratio, and the device is applied to a wireless fidelity WiFi system, as shown in FIG. 12, including:
  • a dividing module 1201 configured to divide subcarriers of orthogonal frequency division multiplexing OFDM symbols that carry data to be transmitted, to obtain multiple partitions;
  • a determining module 1202 configured to determine a plurality of phase factors corresponding to the plurality of partitions, where the plurality of phase factors are used to reduce a peak-to-average ratio of the OFDM symbols;
  • the transmitting module 1203 is configured to transmit multiple phase factors by using a specific subcarrier of the OFDM symbol, and the data transmitted on each of the plurality of partitions is respectively multiplied by a corresponding phase factor and transmitted.
  • phase factor phase factor
  • specific subcarrier subcarrier division
  • peak-to-average ratio peak-to-average ratio
  • method for reducing the peak-to-average ratio etc.
  • the embodiment of the present invention further provides a device for reducing a peak-to-average ratio.
  • the device is applied to a wireless fidelity WiFi system, as shown in FIG.
  • the processor 1301 is configured to divide the subcarriers of the orthogonal frequency division multiplexing OFDM symbols that carry the data to be transmitted, to obtain a plurality of partitions, and determine a plurality of phase factors corresponding to the plurality of partitions, where multiple phase factors are used to reduce a peak-to-average ratio of the OFDM symbols;
  • the transmitter 1304 is configured to transmit a plurality of phase factors using a specific subcarrier of the OFDM symbol; each of the plurality of partitions is multiplied by a corresponding phase factor and transmitted.
  • phase factor phase factor
  • specific subcarrier subcarrier division
  • peak-to-average ratio peak-to-average ratio
  • method for reducing the peak-to-average ratio etc.
  • the embodiment of the present invention further provides a system for reducing a peak-to-average ratio.
  • the system is applied to a wireless fidelity WiFi system, including: the device for reducing the peak-to-average ratio provided in FIG. 12 or the device for reducing the peak-to-average ratio provided in FIG.
  • phase factor phase factor
  • specific subcarrier subcarrier division
  • peak-to-average ratio peak-to-average ratio
  • method for reducing the peak-to-average ratio etc.
  • the embodiment of the present invention further provides a method for reducing a peak-to-average ratio, and the method is applied to a wireless fidelity WiFi system, as shown in FIG.
  • Step 1401 Receive an Orthogonal Frequency Division Multiplexing (OFDM) symbol, where a subcarrier of an OFDM symbol is divided into multiple partitions, where multiple partitions correspond to multiple phase factors, and multiple phase factors are used to reduce peaks of OFDM symbols. Comparing, a specific subcarrier of an OFDM symbol carries a plurality of phase factors, and each of the plurality of partitions carries data multiplied by a corresponding phase factor;
  • OFDM Orthogonal Frequency Division Multiplexing
  • Step 1402 Obtain a plurality of phase factors according to signals carried by a specific subcarrier.
  • Step 1403 Obtain data transmitted by the OFDM symbol according to the phase factor and the plurality of partitions.
  • the specific subcarrier is a reserved subcarrier, where the reserved subcarrier is a reserved subcarrier in a subcarrier of the OFDM symbol;
  • obtaining a plurality of phase factors includes:
  • the phase factor information is turned out into a phase factor.
  • obtaining a plurality of phase factors according to the signal carried by the specific subcarrier further includes:
  • the demodulated data is decoded to obtain phase factor information.
  • converting the plurality of phase factor information into the phase factor comprises:
  • the conversion is performed according to a mapping rule between a plurality of phase factor information and a phase factor, wherein the mapping rule includes a table mapping or a formula mapping.
  • the specific subcarrier is a pilot subcarrier, where the pilot subcarrier carries a product of a corresponding phase factor and a pilot signal of the plurality of phase factors.
  • the determining method of the plurality of phase factors includes:
  • a plurality of phase factors are taken from a finite set such that the PAPR after multiplying the plurality of partitions by a plurality of phase factors is minimized.
  • the limited set is or Or other similar variants.
  • the method provided by the embodiment of the present invention further includes:
  • phase factor phase factor
  • specific subcarrier subcarrier division
  • peak-to-average ratio peak-to-average ratio
  • method for reducing the peak-to-average ratio etc.
  • the embodiment of the present invention further provides a device for reducing a peak-to-average ratio.
  • the method is applied to a wireless fidelity WiFi system, as shown in FIG.
  • the receiving module 1501 is configured to receive orthogonal frequency division multiplexing OFDM symbols, where subcarriers of the OFDM symbol are divided into multiple partitions, and multiple partitions correspond to multiple phase factors, and multiple phase factors are used to reduce OFDM symbols. a peak-to-average ratio, a specific subcarrier of an OFDM symbol carries a plurality of phase factors, and each of the plurality of partitions carries data multiplied by a corresponding phase factor;
  • An obtaining module 1502 configured to obtain multiple phase factors according to signals carried by a specific subcarrier
  • the recovery module 1503 is configured to obtain data transmitted by the OFDM symbol according to the phase factor and the plurality of partitions.
  • phase factor phase factor
  • specific subcarrier subcarrier division
  • peak-to-average ratio peak-to-average ratio
  • method for reducing the peak-to-average ratio etc.
  • the embodiment of the present invention further provides a device for reducing a peak-to-average ratio.
  • the device is applied to a wireless fidelity WiFi system, as shown in FIG. 16, comprising: a processor 1601, a memory 1602, and a receiving The machine 1604 and the bus 1603, wherein the processor 1601, the memory 1602 and the receiver 1604 are connected by a bus 1603 for data transmission, and the memory 1602 is used for storing data of the processor processing 1601;
  • the receiver 1604 is configured to receive orthogonal frequency division multiplexing OFDM symbols, where subcarriers of the OFDM symbol are divided into multiple partitions, and multiple partitions correspond to multiple phase factors, and multiple phase factors are used to reduce OFDM symbols. Peak-to-average ratio, a specific subcarrier of an OFDM symbol carries multiple phase factors, The data carried on each of the plurality of partitions is multiplied by the corresponding phase factor;
  • the processor 1601 is configured to obtain, according to the signal carried by the specific subcarrier, a plurality of phase factors; and according to the phase factor and the plurality of partitions, obtain data of the OFDM symbol transmission.
  • phase factor phase factor
  • specific subcarrier subcarrier division
  • peak-to-average ratio peak-to-average ratio
  • method for reducing the peak-to-average ratio etc.
  • the embodiment of the present invention further provides a system for reducing the peak-to-average ratio, the system is applied to a wireless fidelity WiFi system, including: the device for reducing the peak-to-average ratio provided in FIG. 15 or FIG. 16 provides The device that reduces the peak-to-average ratio.
  • phase factor phase factor
  • specific subcarrier subcarrier division
  • peak-to-average ratio peak-to-average ratio
  • method for reducing the peak-to-average ratio etc.
  • the size of the serial numbers of the above processes does not mean the order of execution, and the order of execution of each process should be determined by its function and internal logic, and should not be implemented by the present invention.
  • the implementation of the examples constitutes any limitation.
  • the disclosed apparatus and method may be implemented in other manners.
  • the device embodiments described above are merely illustrative.
  • the division of the unit is only a logical function division.
  • there may be another division manner for example, multiple units or components may be combined or Can be integrated into another system, or Some features can be ignored or not executed.
  • the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, or an electrical, mechanical or other form of connection.
  • the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the embodiments of the present invention.
  • each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.
  • the above integrated unit can be implemented in the form of hardware or in the form of a software functional unit. Specifically, it can be implemented by means of software and necessary general hardware.
  • the general hardware includes a general-purpose integrated circuit, a general-purpose CPU (English: Central Processing Unit, Chinese: central processing unit), and a general-purpose digital signal processor (English: Digital Signal Processor) , referred to as: DSP), Field Programmable Gate Array (English: Field Programming Gate Array, referred to as: FPGA), Programmable Logical Device (English: Programmable Logical Device, PLD for short), general-purpose memory, general-purpose components, etc. It can be realized by dedicated hardware including an application specific integrated circuit (ASIC), a dedicated CPU, a dedicated memory, a dedicated component, and the like.
  • ASIC application specific integrated circuit
  • the integrated unit if implemented in the form of a software functional unit and sold or used as a standalone product, may be stored in a computer readable storage medium.
  • the technical solution of the present invention contributes in essence or to the prior art, or all or part of the technical solution may be embodied in the form of a software product stored in a storage medium.
  • a number of instructions are included to cause a computer device (which may be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention.
  • the foregoing storage medium includes: a U disk, a mobile hard disk, a read only memory (English: Read Only Memory, abbreviated as ROM), a random access memory (English: Random Access Memory, abbreviated as RAM), a magnetic disk or an optical disk, and the like.
  • ROM Read Only Memory
  • RAM Random Access Memory
  • Software or instructions can also be transferred over a transmission medium.
  • a transmission medium For example, if you use coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL: DSL) or wireless technology (such as infrared, radio and microwave) to transfer software from websites, servers or other remote sources.
  • coaxial cable, fiber optic cable, twisted pair, DSL or wireless technology (such as infrared, radio and Microwave)) is included in the definition of the transmission medium.

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Abstract

本发明实施例提出了一种降低峰均比的方法，包括：将承载待传输数据的正交频分复用OFDM符号的子载波进行划分，得到多个分块；确定多个分块对应的多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比；利用所述OFDM符号的特定子载波传输所述多个相位因子；将所述多个分块中的每个分块乘以对应的相位因子，并进行传输。通过利用特定子载波传输各个分块的相位因子信息，使PTS方法在WiFi***中的应用成为可能，从而有效地降低数据的PAPR。

Description

一种降低峰均比的方法、装置、设备和*** 技术领域
本发明实施例涉及通信技术，特别是一种降低峰均比的方法、装置、设备和***。
背景技术
无线保真(英文：Wireless Fidelity；简称：WiFi)***(或称为无线局域网***)，历经802.11a，802.11b，802.11d，802.11n和802.11ac等各个版本，技术发展越来越成熟，提供的***传输速度也越来越大，目前802.11ac最大已经可以支持1Gbps。另一方面，由于其特有的灵活性，在家用和商用环境中得到了越来越多的应用。
在下一代WiFi***802.11ax中，引入了两种新的技术来提升***的吞吐量，以满足越来越大的通信需求：
一、信道聚合(英文：Channel Bonding)
原有WiFi***中，一般一次只分配20M带宽给用户使用。在后续WiFi标准中，为了提供更高的传输速率，分配的带宽将成倍增加，最高可以分配4个20M，即一次分配80M带宽给用户使用。
二、正交频分多址(英文：Orthogonal Frequency Division Multiple Access；简称：OFDMA)
原有WiFi***中，一个20M带宽划分为64个子载波(英文：Tone或Subcarrier)，用于传输数据的正交频分复用(英文：Orthogonal Frequency Division Multiplexing；简称：OFDM)符号，除0中频子载波、导频子载波和保护子载波外，剩余所有的子载波用于传输数据的子载波全部用于传输一个用户的数据。
在下一代WiFi标准中，为了提高频谱利用效率，引入了OFDMA，也就是在一个OFDM符号上，同时可以传输多个用户的数据。同时，为了提高多用户复用的粒度，将一个20M带宽划分为256个子载波。
OFDMA***是一种多载波调制***，它具有频带利用率高、抗多径衰落能力强等优点。多载波调制信号是由不同频率、不同幅度的信号叠加而得到的，于是，多载波调制***一般都具有较大的峰值平均功率比(英文： Peak-to-Average Power Radio；简称：PAPR)。
一般来说，由于放大器的饱和特性(即：当输入信号大于放大器的标称值时，输出信号会有非线性失真)，输入较大引起的非线性会引起带外辐射和带内失真。一般采用PAPR来定义输入信号的功率特性，由于输入放大器的信号的PAPR过高，就会引起前述的带外辐射和带内失真等问题。
在下一代WiFi***中，为了支持OFDMA，20M带宽内采用256点FFT，且最大支持的带宽由20M增加到80M，PAPR问题会恶化，必须考虑特定的处理方法。
图1为不同FFT点变化的PAPR互补累计分布函数(英文：Complementary Cumulative Distribution Function；简称：CCDF)分布仿真图，具体可以参见图1中不同快速傅里叶变换(英文：Fast Fourier Transform；简称：FFT)点的PAPR结果，其中，不同FFT点对应的不同子载波总数：
64点对应现有20M带宽，64个子载波的PAPR分布，
256点对应现有20M带宽，256个子载波的PAPR分布
1024点对应80M带宽，1024个子载波的PAPR分布
从图1中可以看出，80M带宽，1024个子载波时，PAPR较原来64点FFT要增加2～3dB，也就是PAPR变大，从而影响了***的性能。
发明内容
本发明实施例提出了一种降低峰均比的方法，所述方法应用于无线保真WiFi***，包括：
将承载待传输数据的正交频分复用OFDM符号的子载波进行划分，得到多个分块；
确定多个分块对应的多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比；
利用所述OFDM符号的特定子载波传输所述多个相位因子；
将所述多个分块中的每个分块上传输的数据乘以对应的相位因子，并进行传输。
本发明实施例提出了一种降低峰均比的装置，所述装置应用于无线保真WiFi***，包括：
划分模块，用于将承载待传输数据的正交频分复用OFDM符号的子载波 进行划分，得到多个分块；
确定模块，用于确定多个分块对应的多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比；
传输模块，用于利用所述OFDM符号的特定子载波传输所述多个相位因子，将所述多个分块中的每个分块乘以对应的相位因子，并进行传输。
本发明实施例提出了一种降低峰均比的设备，所述设备应用于无线保真WiFi***，包括：处理器、存储器、发射机及总线，其中所述处理器、存储器及发射机通过所述总线连接进行数据传输，所述存储器用于存储所述处理器处理的数据；
所述处理器用于将承载待传输数据的正交频分复用OFDM符号的子载波进行划分，得到多个分块；确定多个分块对应的多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比；
所述发射机用于利用所述OFDM符号的特定子载波传输所述多个相位因子；将所述多个分块中的每个分块乘以对应的相位因子，并进行传输。
本发明实施例提出了一种降低峰均比的方法，所述方法应用于无线保真WiFi***，包括：
接收正交频分复用OFDM符号，其中，所述OFDM符号的子载波划分为多个分块，所述多个分块对应多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比，所述OFDM符号的特定子载波承载的是所述多个相位因子，所述多个分块中的每个分块上承载的是乘以对应的相位因子的数据；
根据所述特定子载波承载的信号，得到所述多个相位因子；
根据所述相位因子和所述多个分块，得到所述OFDM符号传输的数据。
本发明实施例提出了一种降低峰均比的装置，所述装置应用于无线保真WiFi***，包括：
接收模块，用于接收正交频分复用OFDM符号，其中，所述OFDM符号的子载波划分为多个分块，所述多个分块对应多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比，所述OFDM符号的特定子载波承载的是所述多个相位因子，所述多个分块中的每个分块上承载的是乘以对应的相位因子的数据；
获取模块，用于根据所述特定子载波承载的信号，得到所述多个相位因子；
恢复模块，用于根据所述相位因子和所述多个分块，得到所述OFDM符号传输的数据。
本发明实施例提出了一种降低峰均比的设备，所述设备应用于无线保真WiFi***，包括：处理器、存储器、接收机及总线，其中所述处理器、存储器及接收机通过所述总线连接进行数据传输，所述存储器用于存储所述处理器处理的数据；
接收机，用于接收正交频分复用OFDM符号，其中，所述OFDM符号的子载波划分为多个分块，所述多个分块对应多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比，所述OFDM符号的特定子载波承载的是所述多个相位因子，所述多个分块中的每个分块上承载的是乘以对应的相位因子的数据；
处理器，用于根据所述特定子载波承载的信号，得到所述多个相位因子；根据所述相位因子和所述多个分块，得到所述OFDM符号传输的数据。
其中，将多个分块中的每个分块乘以对应的相位因子是对多个分块(或该OFDM符号)进行降低PAPR的处理，具体地，每个分块中的每个承载待传输数据的子载波乘以该分块对应的相位因子，然后进行传输。
可选地，特定子载波为保留子载波，其中，保留子载波为OFDM符号的子载波中预留的子载波；其中，保留子载波承载相位因子信息，因而传输时无需乘以相位因子。进一步地，利用保留子载波传输相位因子的方式至少有两种：第一种是直接传输相位因子，也就是直接将相位因子承载在保留子载波上进行传输；第二种是将相位因子转换成相位因子信息再进行传输，其中，可以对相位因子信息进行编码、调制或重复等处理。
可选地，特定子载波为导频子载波；进一步地，利用所述OFDM符号的特定子载波传输多个相位因子包括：将多个相位因子承载到导频子载波上进行传输，其中，导频子载波承载多个相位因子中对应的相位因子和导频信号的乘积。应理解，在利用导频子载波传输相位因子时，是不需要对相位因子进行转换和调制的，而是直接将导频信号和该导频子载波上要传输的相位因子相乘，然后承载在导频子载波上进行传输，其中，可以用部分或全部的导频子载波进行传输。
进一步地，发送端和接收端的步骤是相应或相似的，针对发送端发送的进行了降低PAPR处理的OFDM符号以及该OFDM符号中携带的相位因子信 息，接收端相应地从OFDM符号中恢复出相位因子，然后利用相位因子恢复出OFDM符号承载的数据。
进一步地，本发明实施例并不限定对一个OFDM符号的处理，多个OFDM符号可以统一在一起按照本发明实施例提供的方法进行处理，例如，两个OFDM符号，可以统一分块，统一确定相位因子，统一承载在这两个OFDM符号的特定子载波上或用本发明提供的传输方法传输，也可以分别确定相位因子，然后统一用本发明提供的传输方法传输，具体地传输方法至少包括一下几种：(1)直接传输相位因子；(2)将相位因子转换成相位因子信息，对相位因子信息调制后传输；(3)将相位因子转换成相位因子信息，对相位因子信息进行编码、调制后传输，可选地，还可以对调制后的数据进行重复。
进一步地，本发明实施例提供的降低峰均比的方法可以适应多输入多输出(英文：Multi-input Multi-output；简称：MIMO)***，也就是说，对MIMO中每一个流中传输的OFDM符号可以应用本发明实施例提供的方法，多个流传输的多个OFDM符号也可以统一在一起应用本发明实施例提供的方法。
应理解，特定子载波可以为一个或多个，具体地，保留子载波或导频子载波可以为一个或多个。具体需要用部分或全部的特定子载波(也就是说，具体选用哪些特定子载波或特定子载波的个数)来传输相位因子根据传输可靠性或实际需求可以灵活确定，下文中仅给出示例，本发明不做限定。另外，本发明中有具体子载波序号的特定子载波仅是示例性的，对特定子载波具体是哪些子载波并不做限定，在实际应用时可以根据实际情况确定，或者根据标准中预留的子载波或导频子载波的位置确定，只要针对特定子载波应用本发明的方法即落在本发明保护的范围内。
应理解，本发明中的QPSK、QAM等仅是调制方式的示例，具体调制方式还可以是相移键控调制、差分调制、能量调制或其他常见的调制方式，对此本发明不作限定。本发明中的块编码、BCH编码等仅是编码方式的实例，具体编码方式还可以是RS编码、循环编码、卷积编码、Reed–Muller编码或其他常见的编码方式，对此本发明不作限定。
本发明实施例中，将承载待传输数据的正交频分复用OFDM符号的子载波进行划分，得到多个分块；确定多个分块对应的多个相位因子，其中，多个相位因子用来降低OFDM符号的峰均比；利用OFDM符号的特定子载波传输多个相位因子；将多个分块中的每个分块乘以对应的相位因子，并进行传 输。也就是说，在利用OFDM符号传输数据的同时，也利用OFDM符号中的特定子载波传输用于降低该OFDM符号峰均比的相位因子，这样在一个OFDM符号内就可以传输接收端所需的降低峰均比的信息，从而在不增加***资源消耗的情况下，仅需作出较小的调整就可以降低发送的OFDM符号的PAPR，提高传输可靠性。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对现有技术或实施例中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为不同FFT点变化的PAPR CCDF分布仿真图；
图2为OFDM和OFDMA的概念示意图；
图3为PTS原理示意图；
图3a是80M带宽、1024子载波时采用PTS方法后的PAPR分布仿真图；
图4为在OFDMA***中应用PTS的技术原理示意图；
图5为传输方式1的示意图；
图6为传输方式2的示意图；
图7为传输方式3的示意图；
图8为802.11标准中的帧结构示意图；
图9为WiFi***传输相位因子信息的原理示意图；
图10为几种传输相位因子信息的具体实现方式示意图；
图10a是保留子载波在频域的分布示意图；
图10b为802.11ax中1024个子载波的划分方式示意图；
图11a为802.11ad***的PAPR CCDF分布仿真图；
图11为本发明实施例提供的降低PAPR的仿真图；
图12为本发明实施例提供的一种降低峰均比的装置示意图；
图13为本发明实施例提供的一种降低峰均比的设备示意图；
图14为本发明实施例提供的另一种降低峰均比的方法示意图；
图15为本发明实施例提供的另一种降低峰均比的装置示意图；
图16为本发明实施例提供的另一种降低峰均比的设备示意图。
具体实施方式
为了解决下一代WiFi***中PAPR较大的问题，本发明实施例提供了一种降低峰均比的方法和装置，也就是说，利用OFDM符号中的特定子载波传输相位因子，其他传输数据的子载波分块乘以对应的相位因子，这样发送端通过选择合适的相位因子使得传输数据的子载波的PAPR最小化，而接收端可以通过接收到的特定子载波中的相位因子(或相位因子信息)，完成数据恢复，从而实现降低***峰均比。具体地，本发明实施例中的特定子载波可以为为保留子载波或导频子载波。
关于执行主体
本发明实施例中，执行本发明实施例提供的降低峰均比的方法可以是站点、接入点，也可以是终端、网络节点，对此并不限定。具体地，本发明实施例中的接入点(简称：AP，英文：Access Point)，也称之为无线访问接入点或热点等。具体地，AP可以是带有WiFi芯片的终端设备或者网络设备。可选地，AP可以为支持802.11ax制式的设备，进一步可选地，该AP可以为支持802.11ac、802.11n、802.11g、802.11b及802.11a等多种WLAN(英文：Wireless Local Area Network,中文：无线局域网)制式的设备。具体地，本发明实施例中的站点(简称：STA，英文：Station)，可以是无线通讯芯片、无线传感器或无线通信终端；例如：支持WiFi通讯功能的移动电话、支持WiFi通讯功能的平板电脑、支持WiFi通讯功能的机顶盒和支持WiFi通讯功能的计算机。可选地，站点可以支持802.11ax制式，进一步可选地，该站点支持802.11ac、802.11n、802.11g、802.11b及802.11a等多种WLAN制式。
关于OFDM、OFDMA以及保留子载波
图2为OFDM和OFDMA的概念示意图，如图2所示，其中频域数据部分的每一个方格子表示一个子载波承载的数据。对OFDM而言，除了图2中左半部分用灰色显示的0中频(0中频对应直流信号，其上不传输数据)、导频子载波和保护子载波外的所有子载波，都用于传输一个用户的数据；也就是说，频域数据中的白色部分都可以用来传输单用户数据，然后对频域数据进行IFFT即为时域数据。
对OFDMA而言，除了图2中右半部分用灰色显示的0中频和保护子载波外，剩余的子载波分为N个子带(英文：band)，也可以称为资源块(英文：Resource Unit；简称：RU)，不同的子带用于传输不同用户的数据，其中，每个子带均包含导频子载波；也就是说，频域数据中的子载波可以被分配给不同的用户来传输数据，例如：横线填充部分的子载波组成的子带用于传输用户1的数据，竖线填充部分的子载波组成的子带用于传输用户2的数据，然后对频域数据进行IFFT即为时域数据。
在现有的WiFi***中，将输入的数据分块以用于OFDMA传输，而每个数据块(即对应用户的数据块)是承载在子带上进行传输的，关于子带有两种不同的划分方法方法，其区别在于子带的粒度，其中子带的粒度和数据块的粒度是对应的。此处的数据分块和下文的对应相位因子的分块不同，此处的数据分块是针对多用户的分块，每一个子带可以传输一个用户的数据，所以子带上数据块的大小要和子带匹配。
第一种子带划分方式——每个子带占26个子载波，相应地，每个数据块也就占用26个子载波，子带划分方式具体如下：
在20M带宽内采用256点FFT变换，26个子载波划分为一个数据子带，子带划分如下：
两侧的保护子载波个数各为5，6，即有11个子载波用于保护带；
0中频对应的子载波不传输信号；
26个子载波作为一个子带，共有9个子带；
除去上面占用的子载波，目前共有10个子载波没有使用；
更进一步的，在80M带宽内采用1024点FFT变换，分为1024个子载波，子载波的分配方式如下：
两侧的保护子载波个数各为5，6，即有11个子载波用于保护带，不传输数据；
0中频对应的子载波也不传输数据；
26个子载波作为一个子带，共有38个子带；
除去上面占用的子载波，共有24个子载波没有使用。
第二种子带划分方式——每个子带占52个子载波，相应地，每个数据块也就占用52个子载波，子带划分方式具体如下：
在20M带宽内采用256点FFT变换，52个子载波划分为一个子带，子带划 分如下：
两侧的保护子载波各为5，6，即有11个子载波用于保护带；
0中频对应的子载波不传输信号；
52个子载波作为一个子带，共有4个子带；
除去上面占用的子载波，目前共有36个子载波没有使用；
更进一步的，在80M带宽内采用1024点FFT变换，分为1024个子载波，子载波的分配方式如下：
两侧的保护子载波个数各为5，6，即有11个子载波用于保护带，不传输数据；
0中频对应的子载波也不传输数据；
52个子载波作为一个子带，共有19个子带；
除去上面占用的子载波，目前共有24个子载波没有使用。
为方便描述，将没有使用的子载波称为保留子载波(英文：Reserved Tone)，也可以称为预留子载波，还可以被称为残留子载波(英文：Left Tone)：例如第一种划分方式和第二种划分方式中的24个没有使用的子载波，正是由于保留子载波没有被用来传输数据，从而可以利用保留子载波来传输降低当前OFDM符号峰均比的相位因子。
具体地，在802.11ax标准中，是以26子载波为调度的基本单位，可以将其称为一个子带或资源块。具体20M带宽，40M带宽，80M带宽时的设计分别如下所述：
对于20M带宽：
将一个20M带宽划分为256个子载波，将26个子载波划分为一个子带用于传输数据，子载波的分配方式如下：
共有9个子带，占用234子载波；
两侧的保护子载波各为5，6，即有11个子载波用于保护带，不传输数据；
0，±1三个子载波用于零中频，不传输数据；
剩余8个子载波未使用。
对于40M带宽：
将一个40M带宽划分为512个子载波，相对应的，子载波的分配方式如下：
两侧的保护子载波各为12，11，即有23个子载波用于保护带，不传输数 据；
0，±1，±2这五个子载波用于零中频，不传输数据；
18个子带用于传输数据，共占用468个保留子载波。
共有16个保留子载波未使用。
对于80M带宽：
将一个80M带宽划分为1024个子载波，相对应的，子载波的分配方式如下：
两侧的保护子载波各为13，12，即有25个子载波用于保护带，不传输数据；
0，±1，±2这五个子载波用于零中频，不传输数据；
共有37个子带用于传输数据，共占用926个子载波；
剩余32个保留子载波未使用。
关于降低PAPR的方法和相位因子
在OFDM或OFDMA***中，相对于单载波***，其时域信号的PAPR高很多，这会带来很多问题，如降低了发射机功率放大器的效率，也降低了数/模转化器和模/数转化器的信号量化噪声比，是OFDM或OFDMA***本身最不利的因素之一。因此，对于OFDM或OFDMA***，往往要求采用进行特定的处理来降低PAPR，产品中常用的方法有预失真，削波等技术。
其中，部分传输序列(英文：Partial Transmit Sequence；简称：PTS)是消除PAPR众多方法中的一种，图3为PTS原理示意图，如图3所示：
将输入的数据X分为N个块，分别为x1，x2，…，xN；
对上述的N个块分别进行逆快速傅里叶变换(英文：Inverse Fast Fourier Transform；简称：IFFT)；
对上述的N个块分别乘上一个相位因子后再相加，其中，相位因子为：
Figure PCTCN2015072695-appb-000001
Figure PCTCN2015072695-appb-000002
对相加后得到的符号增加循环前缀(英文：Cyclic Prefix；简称：CP)，得到OFDM符号；
其中，通过选择每个块对应的相位因子，使输出的OFDM符号的PAPR最小；因此要利用PTS来降低PAPR的话，需要确定相位因子，并传输相位因子信息(需要将相位因子转换成相位因子信息)，以便于接收方通过接收到 的相位因子信息来恢复数据。
具体地，在发送端的PTS处理如下所述：
OFDM符号中子载波数目为N，所有映射到子载波上的数据组成的序列为x(n)，n＝0，1，…，N-1；
将序列x(n)分为M个不相交的子块，每个子块的长度为L，N＝ML，M，L均为大于1小于N的自然数：
Figure PCTCN2015072695-appb-000003
对xm(n)作IFFT变换得到：ym(n)＝IFFT(xm(n))。
Figure PCTCN2015072695-appb-000004
其中，y(n)为时域发送信号，
Figure PCTCN2015072695-appb-000005
为相位因子；选择合适的相位φm，使y(n)的峰均比最低，即
Figure PCTCN2015072695-appb-000006
其中：序列y(n)的PAPR的定义为:
Figure PCTCN2015072695-appb-000007
即最大功率和平均功率之比。
由上所述，相位φm的选择或确定是PTS算法的核心，以下面两种典型的算法为例对相位φm的选择或确定进行描述，为方便叙述，假定分块的数目为4，即M＝4。
典型算法1：
第一步，设定分块1对应的相位信号为1，分块2对应的相位信号为j，分块3对应的相位信号为ejφ，分块4对应的相位信号为e-jφ；
第二步，对φ从0到π的范围内，以1度的步长，进行搜索以获取最低PAPR：
Figure PCTCN2015072695-appb-000008
典型算法2：
第一步，每一个分块的相位因子为
Figure PCTCN2015072695-appb-000009
，m＝1，2，3，4，φm从为集合
Figure PCTCN2015072695-appb-000010
Figure PCTCN2015072695-appb-000011
中取值；Φ也可以是其它的4种相位的集合，如
Figure PCTCN2015072695-appb-000012
第二步，遍历各种组合，以获取最佳的PAPR结果，即PAPR最小的结果：
Figure PCTCN2015072695-appb-000013
后面针对WiFi标准的详细设计时，是以该方法作为基础的，或者说以φm从集合
Figure PCTCN2015072695-appb-000014
也就是
Figure PCTCN2015072695-appb-000015
从集合{1，j,-1，-j}或
Figure PCTCN2015072695-appb-000016
中取值为例进行阐述。
进行PTS后接收端的处理：
设接收端知道或获得了进行PTS后各个分块对应的相位因子信息，则具体的处理如下：
将一个OFDM符号上的数据，以分块为单位，分别乘上相应相位因子的共轭：
Figure PCTCN2015072695-appb-000017
其中y(n)对应接收到的子载波数目为N的OFDM符号上的数据组成的序列；
对
Figure PCTCN2015072695-appb-000018
按正常信号流程方式处理，即和没有采用PTS方法时一样的处理流程。
由接收端的处理可知，需要传输相位因子信息以使得接收端可以进一步处理，从而实现降低OFDM符号的PAPR。
进一步地，确定所述多个分块对应的多个相位因子包括：多个相位因子从有限集合中取值，以使得多个分块乘以所述多个相位因子后的PAPR最小化。其中，有限集合可以为
Figure PCTCN2015072695-appb-000019
或
Figure PCTCN2015072695-appb-000020
或者其他类似的或经过简单变形的集合。
需要说明的是，本发明实施例中的相位因子，也可以称为相移因子、加权因子、加权系数等，它表示在应用PTS时选用的降低PAPR的系数，它可以不仅仅表现为相位的形式，也可以是其他复数或实数等形式，对此本发明实施例并不限定。
PTS方法可以有效地降低发送信号的PAPR，图3a是80M带宽、1024子载波时采用PTS方法后的PAPR分布仿真图。如图3a所示，采用PTS方法后，1024个子载波OFDM信号的PAPR和64个子载波的OFDM信号相当，从而PTS方法可以有效的缓解由于子载波数目增加导致PAPR增大的问题。
但PTS技术在实际中的应用有一个很大的障碍，影响了它在实际***中的应用。由于在实际***中，每一个OFDM符号的上承载的数据不同，采用PTS算法后，不同OFDM符号对应的相位因子也不相同。而在接收端，如果不知道每一个OFDM符号对应的相位因子，就无法恢复进行PTS处理前的原 信号，从而无法正确解调信号。如果要传输每一个OFDM符号对应的相位因子，需要占用较大带宽，影响***的传输效率。由于这一因素，限制了PTS算法在实际***中的应用。
由于下一代WiFi***中需要支持80M带宽分为1024个子载波的应用场景，从而导致***的PAPR增大，从而影响***性能。而采用PTS算法可以解决上述PAPR增大的问题，但存在如何在不增加带宽的情况下传输相位因子信息给接收机的困难。
进一步地，针对上述情况，本发明提供了一种利用特定子载波，在不增加额外带宽的情况下传输相位因子给接收端的方法，从而使采用PTS解决PAPR问题在实际中真正得到应用。
关于在WiFi***中应用降低PAPR的方法
在下一代WiFi***中，可以应用PTS技术来降低***的PAPR，具体过程如下：
图4为在OFDMA***中应用PTS的技术原理示意图，如图4所示，每一个向上的箭头表示一个子载波，图中只画出了16个箭头，仅是一种示意，但实际中可以有更多或更少的子载波，本发明实施例并不做限定，例如在WiFi***中，每20M可以划分为64个子载波或256个子载波。
设图4中OFDM符号的带宽为80M，共1024个子载波，20M对应一个传输块，共4块。将一个OFDM符号中的子载波分成多个传输块，具体而言，80M带宽分为1024个子载波，子载波的序号从0开始，从低频子载波到高频子载波依次递增，如图4中最左边的子载波为第0个子载波，依次往右排序为第1个子载波、第2个子载波……，直到最右边的子载波为第1023个子载波。其中，第一个传输块包括第0～255个子载波，如图4中的块1；第二个传输块包括第256～511个子载波，如图4中的块2；第三个传输块包括第512～767个子载波，如图4中的块3；第四个传输块包括第768～1023个子载波，如图4中的块4。应当注意，对该1024个子载波的序号也可以从-511到512来进行编号，这样序号为0的子载波为刚好为0中频。
根据一定的算法(例如上文提供的两种典型算法)，确定每一块对应的相位因子，使对应的PAPR最小，例如：相位因子从有限集合中取值，有限 集合可以为
Figure PCTCN2015072695-appb-000021
传输相位因子信息，以便于接收方通过接收到的相位因子信息来恢复数据，具体的处理如下：
每一传输块中的用于传输数据的子载波都乘以该传输块对应的相位因子，例如：图4的块1中的子载波乘以块1对应的相位因子
Figure PCTCN2015072695-appb-000022
块2中的子载波乘以块2对应的相位因子
Figure PCTCN2015072695-appb-000023
块3中的子载波乘以块3对应的相位因子
Figure PCTCN2015072695-appb-000024
块4中的子载波乘以块4对应的相位因子
Figure PCTCN2015072695-appb-000025
导频子载波不做相移处理，也就是说，导频子载波不乘以相位因子；
在保留子载波上传输相位因子信息，其中，每一传输块的保留子载波传输该传输块的相位因子信息。
相对应的，接收机的处理如下：
首先获得每一传输块上的保留子载波上承载的相位因子，具体的获取方法跟传输相位因子信息的方式有关，也就是说，在保留子载波上如何传输相位因子信息，就应用与传输方式对应的获取方式，例如，在保留子载波上用QAM的方式传输相应的相位因子信息，则应用解调QAM的方式获取相应的相位因子信息；
每一传输块的传输数据的子载波信号都乘上相位因子的共轭，消除相移的影响；
其它流程可以参照现有技术实现。
具体地，发送端的处理过程如下：
将输入一个OFDM符号中子载波上映射的数据分成多个子块。具体而言，80M带宽，1024个子载波上映射的数据组成的序列为，n＝0，1，…，N-1，N＝1024，其中，n和子载波序号相对应，其中，保留子载波上对应的承载信号为0或随机信号，也就是说，保留子载波还没有被占用或没有被用来传输数据，保留子载波对应的x(n)为0或随机信号。将x(n)分为4个子块，为xm(n)，
Figure PCTCN2015072695-appb-000026
其中M＝4，L＝256。
由于WiFi***本身的特点，后续处理和上文中的描述略有不同：
1)对xm(n)作IFFT变换得到：ym(n)＝IFFT(xm(n))；
2)选择合适的相位φm，以得到使y(n)的峰均比最低的
Figure PCTCN2015072695-appb-000027
相位的选择参考上文；
3)根据2)中得到的相位φm，经过编码调制后生成在保留子载波上传输的相位因子信息；
4)重新生成x(n)，在保留子载波对应的位置上用3)中得到的相位因子信息替代；
具体地，重新生成x(n)，n＝0，1，…，N-1，N＝1024,其中，n和子载波序号相对应，其中保留子载波上对应的承载信号第3)步中生成的相位因子信息，也就是说，保留子载波对应的x(n)不再为0或随机信号，而是变成3)中得到的相位因子信息。
5)对每一个分块信号乘上对应的相位因子：当子载波n上传输的不是导频信息或相位因子信息时，
Figure PCTCN2015072695-appb-000028
当子载波n上传输的是导频信息或相位因子信息时，
Figure PCTCN2015072695-appb-000029
应当注意，此时的xm(n)是4)中生成的x(n)根据公式(1)得到的，也就是说，xm(n)中保留子载波对应的x(n)也是被3)中得到的相位因子信息替换了。
6)根据上述结果，将
Figure PCTCN2015072695-appb-000030
作为发送信号发送出去。
相对应的，接收端的处理如下：
1)接收到的OFDM符号所有子载波上承载的信号构成的序列为y(n)，n＝0，1，…，N-1，其中，n和子载波序号相对应。
2)解调保留子载波上承载的相位因子信息，获取每一分块上对应的相位φm，m＝1，2，3，4；
3)对y(n)进行如下处理，消除相位因子的影响：
Figure PCTCN2015072695-appb-000031
当子载波n上传输的不是导频信息或相位因子信息时；
y(n)＝y(n)，(m-1)*L≤n≤m*L-1，当子载波n上传输的是导频信息或相位因子信息时；
4)对
Figure PCTCN2015072695-appb-000032
的处理按正常处理流程进行。
关于相位因子的传输方式
下面介绍本发明的相位因子的传输方式。其中，每一传输块上如何在保留子载波传输相位因子，具体有下述三种传输方法：
传输方式1——直接传输相位因子方式：
在每一传输块的保留子载波上直接传输该传输块的相位因子或相位因子。为了保证可靠性，可以在几个保留子载波上重复传输同一相位因子，一般在3或4个保留子载波上传输同一相位因子就可以提供足够的传输可靠性；
接收时利用信道信息首先恢复出每一传输块对应的相位因子，每一个传输块的传输数据的子载波信号都乘上相位因子的共轭，消除相位因子的影响；
图5为传输方式1的示意图，具体如图5所示，在某一传输块上的4个非连续的保留子载波上都传输与该传输块对应的相位因子
Figure PCTCN2015072695-appb-000033
，之所以选用不连续的保留子载波是为了避免频率选择性衰弱的影响，类似地，下述两种传输方式也利用非连续保留子载波来避免频率选择性衰弱的影响。其中，图5中仅列出了用于传输相位因子的保留子载波，其他子载波的分布和数量本发明实施例不作限定，另外，图5是针对某一传输块而言的，像图4中的多个传输块或其他传输块的情形可以参照图5类似得到，另外，传输方式2和传输方式3也是针对某一传输块而言的，多个传输块或其他传输块的情形都可以参照相应传输方式的方法类似得到，在此不再赘述。
传输方式2——能量调制方式：
图6为传输方式2的示意图，如图6所示，传输方式2利用能量调制(或能量检测)的方案，并在能量检测的基础上进行编码来传输。具体来说，在保留子载波上不传输信号时对应比特0(或1)，传输信号时对应比特1(或0)；接收时在保留子载波上检测到的信号能量大于预设门限时得到比特1(或0)，否则得到比特0(或1)。
举例来说，用PTS来进行降峰均比的相位因子有4个，分别为
Figure PCTCN2015072695-appb-000034
Figure PCTCN2015072695-appb-000035
和，采用如下方案编码：用2个比特进行编码，分别为(00，
Figure PCTCN2015072695-appb-000036
)，(01，)，(10，
Figure PCTCN2015072695-appb-000037
)，(11，
Figure PCTCN2015072695-appb-000038
)。
如图6所示，该传输块上的两个子载波中，一个不传输信号，另一个传输信号，则对应的编码为01，相应的相位因子为
Figure PCTCN2015072695-appb-000039
对应传输的能量信号为01。同样的，为了避免频率选择性衰弱，用4组8个保留子载波传输同一信 号。
传输方式3——差分调制方式：
图7为传输方式3的示意图，如图7所示，传输方式3采用差分调制的方法，通过相邻符号上同一子载波之间的相位差来承载每一传输块对应的相位因子。
具体来说，设某一传输块信号上在第s个符号上的相位因子为
Figure PCTCN2015072695-appb-000040
保留子载波上对应的相位信息为Φs。第一个OFDM符号的保留子载波上承载的导频信号为Φ1＝p，第二个OFDM符号的保留子载波上
Figure PCTCN2015072695-appb-000041
第三个OFDM符号的保留子载波上
Figure PCTCN2015072695-appb-000042
依此类推，
Figure PCTCN2015072695-appb-000043
其中，s为正整数。其他子载波按照类似的方式进行差分调制，只不过第一个OFDM符号上子载波对应的限位信息可能不同。另外，在下一代WiFi标准中，可以将最后一个长训练字段(英文：Long Training Field；简称：LTF)或短训练字段(英文：Short Training Field；简称：STF)作为第一个OFDM符号，也就是参考信号。另外，也可以在第一个用于传输的OFDM数据符号作为第一个OFDM符号，该符号不采用本发明所述的降低峰均比的处理方法，相应保留子载波上传输固定的导频信号，如保留子载波上传输的信号均为1。
差分调制的另一种实现方式是采用在相邻两个子载波中传输对应的相位因子。具体来说，设某一传输块信号上在第s个符号上的相位因子为
Figure PCTCN2015072695-appb-000044
两个相邻的保留子载波序号分别为k和k+1，其上传输的导频信号为pk和
Figure PCTCN2015072695-appb-000045
其中pk为已知的导频信号。
可选地，在前面3种传输方式的基础上，为了进一步提高传输可靠性，可以进一步引入编码，也就是说，先对待传输的相位因子(或相位因子转换成的相位因子信息)进行编码，然后再用上述三种传输方式进行传输。
举例来说，以4个传输块为例，假定每个传输块对应有4种相位因子可选，则所有可能的选项为4^4＝2^8＝256种，对应有8个比特需要传输，则可以采用(16，8)块编码进行编码，输出16个比特，其中(16，8)块编码表示输入信息比特为8个，编码块度为16个。对编码后的数据进行DQPSK/QPSK调制，则需要占用8个保留子载波来传输。进一步地，如果有24个保留子载波可用，则可以将DQPSK/QPSK调制后的数据重复3次，映射在24个保留子载波上传输。
应理解，本发明实施例中的DQPSK只是差分调制的一种，也可以采用其 它差分调制方式。同样，QPSK也只是调制方式的一种，也可以采用其它的调制方式，例如QAM等。
通过编码或重复，可以进一步提高传输的可靠性，以及充分利用信道资源。
可选地，上述传输方式是每一个传输块中的保留子载波传输该传输块的相位因子，但是利用部分或全部的保留子载波来传输所有传输块的相位因子也是可以的，也就是说，对保留子载波传输哪一个传输块的相位因子不作限定，而具体实现方法可以参照上面的传输方式得到。
关于信令的修改
进一步地，为了应用本技术到WiFi***中，需要发送端通知接收端是否采用了本发明所提供的降低PAPR的方法以及采用本方法进行分块的块数，这需要修改WiFi协议中的信令设计，如增加额外的指示比特或复用现有字段中的比特。图8为802.11标准中的帧结构示意图，如图8所示，各字段相关说明如下：
短训练字段(英文：Short Training Field；简称：STF)：用于接收机同步接收信号，包括符号同步和频率同步；
长训练字段(英文：Long Training Field；简称：LTF)：用于接收机进行信道估计，获取信道信息；
信令字段(英文：Signal Field)/服务字段(英文：Service Field)：用于承载控制信令，包括编码调制方式等基本信息；
数据字段(英文：Data Field)：承载传输的信道信息；
尾部和填充(英文：Tail&Padding)：用于填充尾比特，使发送的信号数据能够填满整数倍的OFDM符号。
如果添加额外的指示是否采用本发明所述的降峰均比的方法，则需要修改其中的信令字段/服务字段，具体的做法可以在该字段中增加一个比特，该比特为第一值时采用了本发明实施例提供的PTS技术，该比特为第二值时没有采用本发明实施例提供的降低PAPR的方法，例如该比特为1时采用了本发明实施例提供的降低PAPR的方法，为0时没有采用本发明实施例提供的降低PAPR的方法。另外，也可以复用信令字段/服务字段中某个比特，即利用现有的某个比特来指示是否采用本发明实施例提供的降低PAPR的方法。
如果添加额外的指示是否采用本发明所述的降峰均比的方法及分块的块数，则需要修改其中的信令字段/服务字段，具体的做法可以在该字段中增加2个比特，该比特为第一值时不采用本发明实施例提供的PTS技术，该比特为第二值时采用本发明实施例提供的降低PAPR的方法且分块数为2，
该比特为第三值时采用本发明实施例提供的降低PAPR的方法且分块数为4。例如该2比特为00时不采用本发明实施例提供的PTS技术，为01时采用本发明实施例提供的降低PAPR的方法且分块数为2，为10采用本发明实施例提供的降低PAPR的方法且分块数为2。另外，也可以复用信令字段/服务字段中某2个比特，即利用现有的某2个比特来指示是否采用本发明实施例提供的降低PAPR的方法
应理解，上文中以保留子载波为例进行传输随路的相位因子，也就是说，用进行降低峰均比的OFDM符号中的某些子载波来传输降低峰均比时用到的相位因子，然而，可以将利用保留子载波进一步扩展为利用特定子载波，例如，对于802.11ad中的导频子载波同样也可以按照本发明实施例的方法执行。进一步地，可以将本发明扩展到OFDM和OFDMA***，针对单用户的OFDM***，可以利用导频子载波进行传输相位因子，针对多用户的OFDMA***，可以利用保留子载波进行传输相位因子。
具体地，本发明提供的一种降低峰均比的方法包括：
将承载待传输数据的OFDM符号的子载波进行划分，得到多个分块；
确定多个分块对应的多个相位因子，其中，多个相位因子用来降低OFDM符号的峰均比；
利用OFDM符号的特定子载波传输多个相位因子；
将多个分块中的每个分块乘以对应的相位因子，并进行传输。
其中，将多个分块中的每个分块乘以对应的相位因子是对多个分块(或该OFDM符号)进行降低PAPR的处理，具体地，每个分块中的每个承载待传输数据的子载波乘以该分块对应的相位因子，然后进行传输。
可选地，特定子载波为保留子载波，其中，保留子载波为OFDM符号的子载波中预留的子载波；其中，保留子载波承载相位因子信息，因而传输时无需乘以相位因子。进一步地，利用保留子载波传输相位因子的方式至少有两种：第一种是直接传输相位因子，也就是直接将相位因子承载在保留子载 波上进行传输；第二种是将相位因子转换成相位因子信息再进行传输，其中，可以对相位因子信息进行编码、调制或重复等处理。
可选地，特定子载波为导频子载波；进一步地，利用所述OFDM符号的特定子载波传输多个相位因子包括：将多个相位因子承载到导频子载波上进行传输，其中，导频子载波承载多个相位因子中对应的相位因子和导频信号的乘积。应理解，在利用导频子载波传输相位因子时，是不需要对相位因子进行转换和调制的，而是直接将导频信号和该导频子载波上要传输的相位因子相乘，然后承载在导频子载波上进行传输，其中，可以用部分或全部的导频子载波进行传输。
应理解，特定子载波可以为一个或多个，具体地，保留子载波或导频子载波可以为一个或多个。具体需要用部分或全部的特定子载波(也就是说，具体选用哪些特定子载波或特定子载波的个数)来传输相位因子根据传输可靠性或实际需求可以灵活确定，下文中仅给出示例，本发明实施例不做限定。另外，本发明实施例中有具体子载波序号的特定子载波仅是示例性的，对特定子载波具体是哪些子载波并不做限定，在实际应用时可以根据实际情况确定，或者根据标准中预留的子载波或导频子载波的位置确定，只要针对特定子载波应用本发明实施例的方法即落在本发明保护的范围内。
应理解，本发明实施例中的QPSK、QAM等仅是调制方式的示例，具体调制方式还可以是相移键控调制、差分调制、能量调制或其他常见的调制方式，对此本发明实施例不作限定。本发明实施例中的块编码、BCH编码等仅是编码方式的实例，具体编码方式还可以是RS编码、循环编码、卷积编码、Reed–Muller编码或其他常见的编码方式，对此本发明实施例不作限定。
具体地，针对这两种特定子载波，下面给出了进一步的描述。
图9为WiFi***传输相位因子信息的原理示意图，如图9所示，
步骤901：将一个正交频分复用OFDM符号传输的数据分为Q块，其中每一块都有与之对应的一个相位因子，每一个相位因子用q比特表示；
进一步地，根据分块结果，确定相位因子，其中，相位因子使得该OFDM符号的PAPR最小化；
其中，Q、q为正整数；
具体地，OFDM符号上预留部分子载波，也就是保留子载波；对OFDM 符号上的子载波上的分块，确定各个分块的相位因子，发送信号时每个分块上承载的数据都乘以对应的相位因子，以降低所述OFDM符号的峰均比；其中，保留子载波，用于传输上述相位因子；保留子载波上承载相位因子信息，因而不需要和相位因子相乘；
具体地，每一块都有与之对应的一个相位因子，每一个相位因子用q比特表示，也就是说，将Q个(多个)相位因子转换成相位因子信息，以便于用保留子载波进行传输。进一步地，按照相位因子与相位因子信息之间的映射规则进行转换；其中映射规则包括表格映射，公式映射等。
举例来说，将图4所示的80M带宽1024个子载波的OFDM符号在频域上分为4块，以256个子载波(对应20M带宽)为一块，其中每一块都有与之对应的一个相位因子，共4个相位因子，每一个相位因子用2比特表示，该2比特为每一个块对应的相位因子信息，则共有8个比特需要传输，该8个比特为该OFDM符号的相位因子信息。
在实际实现中，在进行PTS时，一般要求将输入数据分M块，每一块乘以相应的相位因子，并用OFDM子载波进行传输，这相当于将OFDM符号在频域上分为M块，并乘以相应的相位因子。
可选地，可以针对Q块中的每一块单独执行以下步骤，这样是每个传输块中的保留子载波传输该传输块的相位因子，当然，也可以将Q个传输块的Q个相位因子统一起来用部分或全部的保留子载波进行传输，以下是以后者为例进行阐述，所以沿用了Q和q等数据，当以前者为例时，相应的Q和q以及其他数据换成一个传输块内相应的数据即可，在此不再赘述。
步骤902：将表示Q个相位因子的Q*q个比特进行编码，得到编码后的k个比特；
其中，表示Q个相位因子的Q*q个比特为相位因子信息；
具体地，编码方式可以选用块编码码，CRC码，奇偶校验码等编码方式。例如，对待传输的8个比特的相位因子信息采用(16，8)块编码，则需要传输编码后的数据16比特；
进一步地，块编码的生成矩阵可以为：
Figure PCTCN2015072695-appb-000046
或G8*12。
应当注意，对相位因子信息进行编码可以增加传输可靠性，但也可以不编码就进行下面的步骤，这可以根据实际需要灵活决定。
步骤903：对编码后的k个比特进行调制，得到K个符号；
其中，k、K为正整数；
调制方式可以采用直接调制，如直接进行QPSK调制，也可以采用传输方式2的能量调制，如比特0对应的子载波上不传输信号，比特1对应的子载波上传输一个固定值的导频信号，还可以采用传输方式3的差分调制，如采用DQPSK调制。
举例来说，对编码后的16比特数据采用DQPSK调制，得到8个符号；
或对编码后的16比特数据采用QPSK调制，得到8个符号；
或对编码后的16比特数据采用能量调制(比特0对应的子载波上不传输信号，比特1对应的子载波上传输一个固定值的导频信号)，得到16个符号。
步骤904：将调制后的K个符号重复p次，得到K*p个符号，然后将重复后的K*p个符号映射到OFDM符号的保留子载波上进行传输；
其中，p为正整数；如图9所示，K个符号重复p次后得到l个符号，其中，l＝K*p；
应当注意，对调制后的符号进行重复可以增加传输可靠性，但也可以不重复就进行子载波映射，这可以根据实际需要灵活决定。
步骤905：将调制后的K个符号或重复后的K*p个符号映射到OFDM符号的保留子载波上进行传输。
将K或K*p个符号映射到OFDM的保留子载波上，首先应当尽可能保证保留子载波在频带上尽可能分散，然后将待传输的符号尽可能分散地映射到部分或全部的保留子载波上进行传输。例如：80M带宽、1024个子载波的OFDM符号，有24个保留子载波，均匀分散在整个频带上，或尽可能保证这 些保留子载波之间有一定的载波间隔；当有小于等于24个符号需要传输时，可以按照相邻的保留子载波间的序号差的方差最小的规则进行映射，然后传输。
进一步地，采用差分调制时用于传输信息的保留子载波和分配的子带无关，接收时不依靠信道信息，如采用DQPSK调制后的符号在接收时可以不依靠信道信息恢复出来；采用能量调制时，根据能量信号来恢复传输的信号，不需要信靠信道信息；采用QPSK调制时将每个用于传输相位因子信息的保留子载波和一个子带结合，接收时可以依靠子带中的信道信息，在接收时需要信道信息进行恢复。因此，采用差分调制的符号重复时只要满足重复后的符号个数小于等于保留子载波的个数即可，但是采用非差分调制的符号因为需要依靠信道信息来恢复，所以在传输费差分调制的符号的保留子载波要与传输数据的子带相邻。
当采用26个子载波为数据块的基本单位时(或者说26个子载波划分为一个子带)，在80M带宽内采用1024点FFT变换，共有38个子带，有24个子载波没有使用。利用这24个子载波可靠地传输每一个传输块(这里的一传输块对应20M带宽，256个子载波，具体见上面介绍)的相位因子信息，以降低峰均比。
当采用52个子载波为数据块的基本单位时(或者说52个子载波划分为一个子带)，在80M带宽内采用1024点FFT变换，共有19个子带，有24个子载波没有使用。利用这24个子载波可靠地传输每一个传输块(这里的一传输块对应20M带宽，256个子载波，具体见上面介绍)的相位因子信息，以降低峰均比。实现方案和26个子载波为一个子带时基本思路相同，但因为此方案的子带个数(为19)小于保留子载波的个数(为24)，利用非差分调制时，重复次数要受到子带个数(为19)的约束，所以具体的设计有所不同。
图10为几种传输相位因子信息的具体实现方式示意图，如图10所示，其中，实现方式1001、实现方式1002和实现方式1003采用上面提到的第一种分块方式，也就是将26个子载波划分为一个子带，80M带宽、1024个子载波的情况下的划分得到38个子带，24个保留子载波，保留子载波的分布规律根据子载波映射时的需要确定。实现方式1004、实现方式1005和实现方式1006采用上面提到的第二种分块方式，也就是将52个子载波划分为一个子带，80M带宽、1024个子载波的情况下的划分得到19个子带，24个保留子载波，保留 子载波的分布规律根据子载波映射时的需要确定。
图10a是保留子载波在频域的分布示意图。如图10a所示，其中较长的箭头表示0中频，长方形表示子带，较短的箭头表示保留子载波，两个子带之间有一个保留子载波。图10a中提供了三种映射的方式，在进行子载波映射的时候可根据相邻的保留子载波间的序号差的方差最小的规则进行选择，另外，图10a仅提供了保留子载波分布的示意，没有限定具体子载波或子带的数目，其中，子带和相邻的保留子载波构成了一个重复结构，对这个重复结构的数目应以实际情况为准，具体实现应当根据实际需要适当调整，对此本发明实施例不作限定。
具体地，图10中的6种具体实现方式是以80M带宽、1024个子载波为例，它分为4个传输块，需要传输8比特的相位因子信息。
在实现方式1001中，8比特的相位因子信息经过(16,8)块编码后得到16比特数据，将16比特数据进行DQPSK调制后得到8个符号，将调制后的8个符号重复3次，得到24个符号，然后将这24个符号映射到24个保留子载波上，这24个保留子载波的一种可能的分布规则为：(188 215 242 269 296 323 350 377 404 431 458 485 539 566 593 620 647 674 701 728 755 782 809 836)，这种方式是保留子载波集中在靠近频带中心的位置，如图10a中的分布方式1001a；这24个保留子载波的另一种可能的分布规则为：(32 59 86 113 140 167 194 221 248 275 302 329 991 964 937 910 883 856 829 802 775 748 721 694)，这种方式是保留子载波集中在靠近频带边缘的位置，如图10a中的分布方式1002a。其中，子载波的序号按照排列顺序从0到1023。
在实现方式1002中，8比特的相位因子信息经过(16,8)块编码后得到16比特数据，将16比特数据进行QPSK调制后得到8个符号，将调制后的8个符号重复3次，得到24个符号，然后将这24个符号映射到24个保留子载波上，这24个保留子载波的一种可能的分布规则为：(188 215 242 269 296 323 350 377 404 431 458 485 539 566 593 620 647 674 701 728 755 782 809 836)，这种方式是保留子载波集中在靠近频带中心的位置，如图10a中的分布方式1001a；这24个保留子载波的另一种可能的分布规则为：(32 59 86 113 140 167 194 221 248 275 302 329 991 964 937 910 883 856 829 802 775 748 721 694)，这种方式是保留子载波集中在靠近频带边缘的位置，如图10a中的分布方式1002a。其中，子载波的序号按照排列顺序从0到1023。
在实现方式1003中，8比特的相位因子信息经过(16,8)块编码后得到16比特数据，将16比特数据进行能量调制后得到16个符号，因为只有24个保留子载波，所以无法将16个符号全部重复后映射到保留子载波上，所以本发明实施例在实现方式1003中没有重复，当然，也可以将调制后的16个符号中的一部分进行重复以充分利用24保留子载波，对此本发明实施例不作限定。将调制后的16个符号映射到24个保留子载波中的16个保留子载波上，这16个保留子载波的一种可能的分布规则为：(296 323 350 377 404 431 458 485 539 566 593 620 647 674 701 728)，这种方式是保留子载波集中在靠近频带中心的位置，如图10a中的分布方式1001a；这24个保留子载波的另一种可能的分布规则为：(32 59 86 113 140 167 194 221 883 856 829 802 775 748 721 694)，这种方式是保留子载波集中在靠近频带边缘的位置，如图10a中的分布方式1002a。其中，子载波的序号按照排列顺序从0到1023。
在实现方式1004中，8比特的相位因子信息经过(16,8)块编码后得到16比特数据，将16比特数据进行DQPSK调制后得到8个符号，将调制后的8个符号重复3次，得到24个符号，然后将这24个符号映射到24个保留子载波上，这24个保留子载波的一种可能的分布规则为：(5 6 7 60 113 166 219 272 325 378 431 484 538 591 644 697 750 803 856 909 962 1015 1016 1017)，其中，由于以52个子载波为一个子带的情况下，只有19个子带和24个保留子载波，首先分配5，6，7和1015，1016，1017为保留子载波(第0～5个子载波，和第1018～1023个子载波为保护子载波，不传输数据)，剩下的保留子载波，在两个数据块子带之间***一个保留子载波，正好分配18个保留子载波(注意第512个子载波为0中频不传输数据)，如图10a中的分布方式1003a。
在实现方式1005中，8比特的相位因子信息经过(16,8)块编码后得到16比特数据，将16比特数据进行QPSK调制后得到8个符号，将调制后的8个符号重复2次，得到16个符号，然后将这16个符号映射到24个保留子载波中的16个保留子载波上，这是和实现方式1002不同的地方，由于只有19个子带，且在恢复QPSK调制的符号时需要利用信道信息，这需要保留子载波和子带相邻，因此映射时的符号个数要小于等于子带的个数，因此最多只能采用16个保留子载波(或小于等于19个保留子载波)进行传输。也就是说，这里的24个子载波中只用了16个子载波传输控制信息，主要是因为QPSK调制在解调时需要信道信息，信道信息只能在子带中获取。由于只有19个子带，如果 一个子带加1个保留子载波最多只有19个，如果子带加2个或2个以上保留子载波，此时可能导致解调时插值出来的信道信息(即利用子带插值出保留子载波的信道信息)不准确，所以这里只选取了16个保留子载波(对应16个子带)传输控制信息。这16个保留子载波的一种可能的分布规则为：(88 141 194 247 300 353 406 459 565 618 671 724 777 830 883 936)，这种方式是保留子载波集中在靠近频带中心的位置，如图10a中的分布方式1001a；这24个保留子载波的另一种可能的分布规则为：(57 110 163 216 269 322 375 428 646 699 752 805 858 911 964 1017)，这种方式是保留子载波集中在靠近频带边缘的位置，如图10a中的分布方式1002a。其中，子载波的序号按照排列顺序从0到1023。
在实现方式1006中，8比特的相位因子信息经过(16,8)块编码后得到16比特数据，将16比特数据进行能量调制后得到16个符号，因为只有24个保留子载波和19个子带，所以无法将16个符号全部重复后映射到保留子载波上，所以本发明实施例在实现方式1003中没有重复，当然，也可以将调制后的16个符号中的一部分进行重复以充分利用24保留子载波，对此本发明实施例不作限定。将调制后的16个符号映射到24个保留子载波中的16个保留子载波上，这16个保留子载波的一种可能的分布规则为：(88 141 194 247 300 353 406 459 565 618 671 724 777 830 883 936)，这种方式是保留子载波集中在靠近频带中心的位置，如图10a中的分布方式1001a；这24个保留子载波的另一种可能的分布规则为：(57 110 163 216 269 322 375 428 646 699 752 805 858 911 964 1017)，这种方式是保留子载波集中在靠近频带边缘的位置，如图10a中的分布方式1002a。其中，子载波的序号按照排列顺序从0到1023。
进一步地，对于802.11ax中的80M带宽、1024个子载波的情况，本发明实施例具体提供了如下处理：
图10b为802.11ax中1024个子载波的划分方式示意图，如图10b所示，整个1024个子载波被分成4块，分别为块1、块2、块3和块4，每一块都有若干个子带和保留子载波，采用26个子载波为一个子带，，将80M带宽分为1024点子载波，共有37个子带，有32个保留子载波没有使用，具体的如下：
25个子载波用于保护子载波，左边13个，右边12个；
其中中间的5DC表示五个中频(或统称0中频)，5个中频不传输数据， 子载波序号分别为0，-1，1，2，3；
37个子带或资源块用于数据传输，其中位于0中频两侧的各13个子载波共同组成一个子带；
2个保留子载波一组，共32个子载波，具体的分布位置(或子载波序号)为(-498，-497，-444，-443，-390，-389，-336，-335，-256，-255，-202，-201，-148，-147，-94，-93，95，96，149，150，203，204，257，258，337，338，391，392，445，446，499，500)，子载波的序号从-511到512。
要实现利用全部或部分的32个保留子载波可靠地传输所有分块的相位因子(或相位因子信息)，从而可以在***中采用PTS方法降低峰均比。针对上面的描述，应用上面描的方法，几种设计方案如下所述。
上述1024个子载波可以分为2块，也可以分为4块。当上述1024个子载波划分为2块时，具体可以划分为：块1为子载波-511到0；块2为子载波1到512。上述1024个子载波划分为4块，具体为：块1为子载波-511到-257；块2为子载波-256到0；块3为子载波1到258；块4为子载波259到512；
下面的描述以1024个子载波划分为4块为基本方案，划分为2块时的处理类似，不再赘述。
上述的划分保证每一分块中都有8个保留子载波。
方案1——直接传输相位因子：
在4个块中，每一块对应的相位因子分别为
Figure PCTCN2015072695-appb-000047
以第一块为例，有两种选择：选择(-498，-497,-444，-443，-390，-389，-336，-336)8个子载波上都传输
Figure PCTCN2015072695-appb-000048
或选择其中的4个来传输，此时每一对子载波中各选一个，如(-498，-444，，-390，-336，-335)传输
Figure PCTCN2015072695-appb-000049
其他块的传输类似，可以参考第一块的处理方式得到，在此不再赘述。
方案2——能量调制方式：
在4个块中，每一块对应的相位因子分别为
Figure PCTCN2015072695-appb-000050
设相位的选择只有4种可能的值中选择，如
Figure PCTCN2015072695-appb-000051
对应关系如下表所示，其中m＝1,2,3,4：
表1 能量调制方式的相位和比特之间的映射关系
Figure PCTCN2015072695-appb-000052
以第一块为例，当
Figure PCTCN2015072695-appb-000053
在(-498，-444，-390，-336，)这4个子载波上不传输信号(或传输随机信号)，在(-497,-443，-389，，-335)传输一个固定能量的信号。也就是说，在每一对保留子载波上，如(-498，-497)传输01的能量信号。其他块的传输类似，可以参考第一块的处理方式得到，在此不再赘述。
方案3——差分调制的方式：
该方案有2种实现方式，均以其中某一分块的处理方式为例，其他块的传输类似，可以参考第一块的处理方式得到，在此不再赘述。
第一种实现方式，在相邻两个符号的同一子载波之间进行差分调制，具体如下：
在第1个OFDM符号上，所有保留子载波上传输已知的导频信息，如都为Φ0；
某个分块的第n个符号上对应相位因子为
Figure PCTCN2015072695-appb-000054
保留子载波上对应的相位信息为Φn，则
Figure PCTCN2015072695-appb-000055
用来差分调制的第1个OFDM符号可以选STF或LTF中的最后一个符号；或者将第一个OFDM符号不进行降PAPR处理，所有的保留子载波上传输的导频信号均为1或已知信号，将其做为用来差分调制的第1个OFDM符号。
保留子载波可以选择所有32个，也可以选择其中的部分。同样以第一块为例，选择(-498，-497,-444，-443，-390，-389，-336，-336)这8个子载波上都传输Φn，或选择其中的4个来传输，此时每一对子载波中各选一个，如(-498，-444，-390，-336，-335)传输Φn。
φn可以是按照相应算法得出的最佳相位，也可以是方案2中根据表1得出的两位比特信息，再根据这两个比特进行QPSK调制后的结果。
第二种实现方式，在同一个符号的相邻两个载波之间进行差分调制，具体如下：
分块m其对应相位为φm，对应第n个符号上对应相位因子为
Figure PCTCN2015072695-appb-000056
在第k个子载波上传输已知的导频信息p，在第k+1个子载波上传输已知的导频信息
Figure PCTCN2015072695-appb-000057
以第一块为例，在在(-498，-444，-390，-336)这4个子载波上传输p，在(-497，-443，-389，-335)传输
Figure PCTCN2015072695-appb-000058
。
φm可以是按照相应算法得出的最佳相位，也可以是方案2中根据表1得出的两位比特信息，再根据这两个比特进行QPSK调制后的调制符号。
用来差分调制的第1个OFDM符号可以选STF或LTF中的最后一个符号；或者将第一个OFDM符号不进行降PAPR处理，所有的保留子载波上传输的导频信号均为1或已知信号，将其做为用来差分调制的第1个OFDM符号。
方案4——差分调制+编码的方式：
采用差分调制+编码的方法来传输相位因子，首先要在控制信令中需要增加一个指示，用于通知接收端在发送符号中是否采用了本发明所提到的降峰均比处理方法；
将1024个子载波分为4个块，每一块乘上一个对应的相位因子，每个相位因子以2个比特代表，则共有8个比特需要传输，相位和比特之间映射关系请参见表1表；
8个比特的相位因子信息编码，编码后的数据为16比特，具体可以采用(16，8)块编码，1/2的咬尾卷积码等；
采用DQPSK调制，生成8个符号；
若重复4遍，N＝4,则输出32个符号，占用所有的32个保留子载波；
若重复3遍，N＝3,则输出24个符号，则在每一块中的4对子载波取3对，如第一块选择(-498，-497,-444，-443，-390，-389，-336，-336)中的(-498，-497，-444，-443，-390，-389)这六个子载波。
方案5——QPSK调制+编码的方式：
采用QAM调制+编码(具体到实现方案是采用QPSK)的方法来传输相移信息，首先要在控制信令中需要增加一个指示，用于通知接收端在发送符号中是否采用了本发明所提到的降峰均比处理方法；
将1024个子载波分为4个块，每一块乘上一个对应的相位因子，每个相位因子以2个比特代表，则共有8个比特需要传输，相位和比特之间映射关系请参见表1表；
8个比特的相位因子信息编码，编码后的数据为16比特，具体可以采用(16，8)块编码，1/2的咬尾卷积码等；
采用QPSK调制，生成8个符号；
若重复4遍，N＝4,则输出32个符号，占用所有的32个保留子载波；
若重复3遍，N＝3,则输出24个符号，则在每一块中的4对子载波取3对，如第一块选择(-498，-497,-444，-443，-390，-389，-336，-336)中的(-498，-497，-444，-443，-390，-389)这六个子载波。
方案6——能量调制+编码的方式：
采用能量调制+编码(具体到实现方案是采用QPSK)的方法来传输相移信息，首先要在控制信令中需要增加一个指示，用于通知接收端在发送符号中是否采用了本发明所提到的降峰均比处理方法；
将1024个子载波分为4个块，每一块乘上一个对应的相位因子，每个相位因子以2个比特代表，则共有8个比特需要传输，相位和比特之间映射关系请参见表1表；
8个比特的相位因子信息编码，编码后的数据为16比特，具体可以采用(16，8)块编码，1/2的咬尾卷积码等；
采用能量调制，生成32个符号；
将调制中后的符号用所有的32个保留子载波传输。
应理解，在802.11ax中，在每个子带或资源块中有导频子载波，导频子载波在具体传输时不承载待传输数据，因而，在实现本发明实施例提供的方法时，当分块承载的数据乘以该分块对应相位因子时，该分块中的导频子载波(或其承载的导频信号)不需要乘以相位因子。
举例来说，设OFDM符号中输入数据为x(n)，经过PTS变换后的数据为y(n)，n＝0,1,2，…，N-1，其中，n为子载波的序号，N为子载波的个数。
当n不是导频子载波序号时，进行如下操作：
Figure PCTCN2015072695-appb-000059
且n对应的子载波不为保留子载波或导频子载波；
其中
Figure PCTCN2015072695-appb-000060
为相位因子，m＝1，2，3，4，φm从为集合
Figure PCTCN2015072695-appb-000061
中取值，也就是
Figure PCTCN2015072695-appb-000062
从集合
Figure PCTCN2015072695-appb-000063
中取值，以使得输出承载输出数据的OFDM符号的PAPR最小化。
对相位因子信息进行编码调制：
产生8比特b0b1b2b3b4b5b6b7来表示相位因子信息φm,m＝0，1，2，3，具体对应规则如下表所示：
Figure PCTCN2015072695-appb-000064
应理解，这种对应规则只是一种方式，简单的变形也在本发明的保护范围内，例如：
Figure PCTCN2015072695-appb-000065
分别对应{11,10,01,00}等。
对b0b1b2b3b4b5b6b7进行块编码，得到输出比特[b′0b′1b′2…b′15]＝mod([b0 b1 b2…b7]*G8*16，2)，其中G8*16为一个输入8比特，输出16个比特的块编码器，mod表示对2求余。举例而言，G8*16可以为下述矩阵
Figure PCTCN2015072695-appb-000066
除上述块编码外，还可以采用BCH(Bose-Chauduri-Hocquenghem)码(15，11)，这里需要输入的信息比特长度为11,编码后的码长为15比特。为了适应本发明实施例的要求，需要对该编码过程做一定的处理，此时的处理为：将b0b1b2b3b4b5b6b7后面填充3个0扩充到11比特，得到b0b1b2b3b4b5b6b7000，对该11比特进行(15，11)的BCH编码，编码后得到输出比特[b′0b′1b′2…b′14b′15]，其中b′15为填充的0值(即补充冗余比特0)。
对b′0b′1b′2…b′15进行QPSK调制，则调制后的数据为ys,0,ys,1,ys,2,ys,3,ys,4,ys,5,ys,6,ys,7，其中，s为OFDM符号的序号。
将ys,0,ys,1,ys,2,ys,3,ys,4,ys,5,ys,6,ys,7重复3遍可以得到
Figure PCTCN2015072695-appb-000067
将
Figure PCTCN2015072695-appb-000068
乘以第s-1个OFDM符号上的相位因子信息OFDM符号上的相位因子信息即y's,t，即y's,t＝ys,t*y's-1,t，其中，t＝0,1,2,3，…,23。
最后将这24个符y′s,t，t＝0，1，…，23号映射到保留子载波上。
除上述例子外，还可以采用上述编码外，还可以采用Reed–Muller编码来实现发明的实例,具体实现如下。对b0b1b2b3b4b5b6b7进行Reed–Muller编码，得到输出比特[b′0b′1b′2…b′31]＝mod([b0 b1 b2…b7]*G8*16，2)，其中G8*32为一个输入8比特，输出32个比特的编码器,mod表示对2求余。举例而言，G8*16 可以为下述矩阵
Figure PCTCN2015072695-appb-000069
对b′0b′1b′2…b′31进行QPSK调制，则调制后的数据为ys,0,ys,1,ys,2,ys,3,ys,4,ys,5,ys,6,…ys,15，其中，s为OFDM符号的序号。
将ys,0,ys,1,ys,2,ys,3,ys,4,ys,5,ys,6,…ys,15重复2遍可以得到
Figure PCTCN2015072695-appb-000070
将
Figure PCTCN2015072695-appb-000071
乘以第s-1个OFDM符号上的相位因子信息OFDM符号上的相位因子信息即y′s,t，即y′s,t＝ys,t*y′s-1,t，其中，t＝0,1,2,3，…,31。
最后将这32个符y′s,t，t＝0，1，…，31号映射到保留子载波上。
应理解，上述例子是分两步实现DQPSK的，也就是先进行QPSK，然后再乘以相位因子来实现的，并且在两步中间***的重复3遍这一步骤，但是具体原理和方式和本发明实施例是一致的。
由上述例子可知，本发明实施例利用OFDM符号中的保留子载波来传输用于减小(OFDM符号的)PAPR的相位因子，其中，相位因子根据本发明实施例提供的PTS方法可以得到，然后利用保留子载波来传输相位因子。具体地，将相位因子根据对应规则转换为相位因子信息，然后对相位因子信息进行编码、调制或重复后，映射到保留子载波上进行传输。
802.11ad是IEEE 802.11(或称为WLAN，无线局域网)***中的一个子***，工作于60GHz高频段，主要用于实现家庭内部无线高清音视频信号的传输，为家庭多媒体应用带来更完备的高清视频解决方案，也称作WiGig(60GHz Wi-Fi)。相对于目前的WiFi技术，802.11ad技术在多媒体应用方面具有高容量、高速率(PHY采用OFDM多载波方案时最高传输速率可达7Gbps、采用单载波调制方案时最高传输速率可达4.6Gbps)、低延迟、低功耗等特点。
图11a为802.11ad***的PAPR CCDF分布仿真图，如图11a所示，由于802.11ad工作于60GHz的高频段，对于PAPR问题更为敏感，因为在高频段下动态范围大的放大器极为昂贵，要使基于512个子载波划分的OFDM***正常工作，所需要的放大器的成本限制了802.11ad***的应用。
由于在802.11ad***中，OFDM***PAPR问题导致***要采用代价高昂的放大器，从而限制了11ad***的应用。相应的，也可以将PTS算法用于802.11ad降低PAPR，本发明提供了一种复用导频子载波来使用PTS算法的方法，从而有效解决PAPR问题。
进一步地，一个OFDM符号由512个子载波构成(例如：在802.11ad***中的OFDM符号)，也可以通过本发明实施例提供的方法降低峰均比。但是，应当注意的是，相比于上文用保留子载波随路传输当前OFDM符号的保留子载波，在本实施例中，利用是利用导频子载波传输当前OFDM符号的相位因子的，也就是说，导频子载波不仅可以用来传输导频信号，也被用来传输相位因子。具体过程如下：
一个OFDM符号的512个子载波的序号从-255到256来进行编号，即-255，-254，-253，…，-1,0,1,2，…，255,256；这样序号为0的子载波为刚好为0中频。另外，一个OFDM符号的512个子载波划分如下：
序号为(-150,-130,-110,-90,-70,-50,-30,-10,10,30,50,70,90,110,130,150)的子载波用于传输导频信号；
序号为(0,+1,-1)的子载不传输任何信号；
序号大于177或小于-177的子载波上不传输任何信号；
剩余的336个子载波用于传输数据符号。
可以将上述OFDM符号的512个子载波分为若干块，例如：分为2或4块，每一块子载波上承载的数据和导频都乘以该块对应的相位因子，可以针对每一块选择相位因子，使得该OFDM符号的PAPR最小，其中，可以利用上文提供的两种典型算法确定相位因子。可选地，具体分块方式如下：
以分为2块为例，第一块对应的子载波序号为-255到0；第二块对应的子载号序号为1到256；
以分为4块为例，第一块对应的子载波序号为-255到-90；第二块对应的子载号序号为-89到0；第三块对应的子载号序号为1到89；第四块对应的子载号序号从90到256。
1)分为2块时，发送信号时采用如下方式：
Figure PCTCN2015072695-appb-000072
其中Ts为采样时间，q为采样序号，NTones＝512为子载波总数，NSYM为要发送的OFDM符号数，TSYM为OFDM符号对应的时隙长度，TGI为保护间隔对应的时隙长度，Dk，n为发送的数据，pn+1Pk为导频信号，exp（jφ1），exp(jφ2)为降低PAPR所引进的相位因子，
Figure PCTCN2015072695-appb-000073
为加窗函数，NSR＝177。
2)分为4块时，发送信号时采用如下方式：
Figure PCTCN2015072695-appb-000074
其中Ts为采样时间，q为采样序号，NTones＝512为子载波总数，NSYM为要发送的OFDM符号数，TSYM为OFDM符号对应的时隙长度，TGI为保护间隔对应的时隙长度，Dk，n为发送的数据，pn+1Pk为导频信号，exp(jφ1),exp(jφ2),exp(jφ3),exp(jφ4)为降低PAPR所引进的相位因子，
Figure PCTCN2015072695-appb-000075
为加窗函数，NSR＝177。
可选地，如果未使用本发明实施例提供的降低PAPR的方法，可以令上述发送信号中的相位因子为1，从而兼容现有的标准。
由于在本实施例中相位因子直接在导频上传输，相位因子选择不受限制，可以从固定的集合中选取，也可以采用其它的方法获取的任意值。
相应地，接收端需要做一定的调整。在802.11ad的OFDM符号中，导频子载波是用于获到相位偏差的，而相位偏差可以通过相位偏差因子体现。在没有使用本方法前，为了获取相位偏差因子，一般的算法如下所述。
在第k个子载波接收到的信号为：
Figure PCTCN2015072695-appb-000076
其中k为导频子载波的序号{-150,-130,-110,-90,-70,-50,-30,-10,10,30,50,70,90,110,130,150}，zk为噪声，hk为已知的信道，ejθ为相位偏差因子，rk为接收信号。
相位偏差因子采用如下方法获取：
Figure PCTCN2015072695-appb-000077
其中Γ为导频子载波的序号集合{-150,-130,-110,-90, -70,-50,-30,-10,10,30,50,70,90,110,130,150}。
获得
Figure PCTCN2015072695-appb-000078
后，利用该值对所有的信道信息进行补偿：
Figure PCTCN2015072695-appb-000079
其中k＝-177，…，177。
采用进行补偿后的信道信息对接收到的信号进行信道均衡。
引入本算法后，由于不同块引入了不同的相位因子，因此接收算法要做相应更改。
以分为两块为例：
对于第一个分块，利用导频子载波{-150,-130,-110,-90,-70,-50,-30,-10}获得第一个分块的相位偏差因子与相位因子之积，其中接收信号为：
Figure PCTCN2015072695-appb-000080
k∈Γ1，Γ1＝{-150,-130,-110,-90,-70,-50,-30,-10}。为方便描述，令
Figure PCTCN2015072695-appb-000081
同样，对
Figure PCTCN2015072695-appb-000082
估计如下：
Figure PCTCN2015072695-appb-000083
获得
Figure PCTCN2015072695-appb-000084
后，利用该值对所有第一个分块上的信道信息进行补偿：
Figure PCTCN2015072695-appb-000085
其中k＝-177，-176，…，0。采用进行补偿后的信道信息对第一个分块上接收到到的信号进行信道均衡。
对于第二个分块，利用导频子载波{-150,-130,-110,-90,-70,-50,-30,-10}获的第二个分块的相位偏差因子与相位因子之积，其中接收信号为：
Figure PCTCN2015072695-appb-000086
k∈Γ2，Γ2＝{10,30,50,70,90,110,130,150)}。为方便描述，令
Figure PCTCN2015072695-appb-000087
同样，对
Figure PCTCN2015072695-appb-000088
估计如下：
Figure PCTCN2015072695-appb-000089
获得
Figure PCTCN2015072695-appb-000090
后，利用该值对所有第二个分块上的信道信息进行补偿：
Figure PCTCN2015072695-appb-000091
其中k＝1，2，…，177。采用进行补偿后的信道信息对第二个分块上接收到到的信号进行信道均衡。
在接收端，基于导频子载波获取相位偏差的估计也要根据分块的情况进行调整。对于分成四块的情况，对相位偏差和相位补偿(与相位偏差对应，是相位偏差的共轭或相反数)的估计调整如下：
对于第一个分块，相位偏差的估计可以根据导频子载波(-150，-130， -110，-90)的信道响应而得到；
对于第二个分块，相位偏差的估计可以根据导频子载波(-70，-50，-30，-10)的信道响应而得到；
对于第三个分块，相位偏差的估计可以根据导频子载波(10，30，50，70)的信道响应而得到；
对于第四个分块，相位偏差的估计可以根据导频子载波(90，110，130，150)的信道响应而得到。
由上知，应用本发明实施例提供的方法需要进行的调制非常小，所以便于实现降低PAPR。对于分成四块的其他步骤与分成两块的情况类似，可以参考上述例子得到，在此不再赘述。
根据802.11的标准，在OFDM帧头字段预留2比特，用来指示是否应用了本发明实施例提供的方法，或用来指示使用了具体哪种方法，具体如下：
该2比特为00(或值为0)时，表示802.11ad的接收端接收的OFDM符号和现有的OFDM符号相同；或表示未采用本发明实施例提供的降低PAPR的方法；
该2比特为01(或值为1)时，表示采用本发明实施例提供的分为两个分块的降低PAPR的方法；
该2比特为10(或值为2)时，表示采用本发明实施例提供的分为四个分块的降低PAPR的方法；
该2比特为11(或值为3)时，表示接收端可以忽略，或表示该2比特无意义。
图11为本发明实施例提供的降低PAPR的仿真图，如图11所示，对于定向多千兆(英文：Directional Multi-Gigabit；简称：DMG)OFDM应用本发明实施例提供的方法，其中相关参数及结果如表2所示：
表2 图11的仿真参数及结果
分块数目 相位因子的选取集合 在Pr＝0.1时的增益
2 1,-1 0.8dB
2 1,j,-1,-j 1.2dB
4 1,-1 1.5dB
4 1,j,-1,-j 2.2dB
在表2中相位因子的选取集合表示在确定相位因子时，可以从中选取作为相位因子的集合，例如：{1，j，-1，-j}，对应上文提供的典型算法2。
通过本发明实施例提供的方法可以在较小调整或修改的情况下活动较大的PAPR增益。
通过在发送的信号中采用PTS的方法来降低发送信号的PAPR，同时利用特定子载波传输输随路的控制信息(例如：相位因子)，使接收机能够恢复出原有信号。
通过利用特定子载波传输各个分块的相位因子信息，使PTS方法在WiFi***中的应用成为可能，从而有效地降低数据的PAPR。
相对应于上面的实施例，本发明还提供了一种用于多天线时的降低峰均比方法。同样以802.11ax为例，80M带宽时需要支持1到8天线。
当采用26个子载波为一个子带时，将80M带宽分为1024点子载波，共有37个子带，有32个保留子载波没有使用，具体的子载波划分如图10b所示：
25个子载波用于保护子载波,左边13个，右边12个；
5个中频不传输数据，分别为0，-1，1，2，3；
37个子带或资源块用于数据传输，其中位于0中频两侧的各13个子载波共同组成一个子带；
2个保留子载波一组，共32个子载波，具体的映射位置为(-498，-497，-444，-443，-390，-389，-336，-335，-256，-255，-202，-201，-148，-147，-94，-93，95，96，149，150，203，204，257，258，337，338，391，392，445，446，499，500)，子载波的序号从-511到512。
具体到多天线时，依然以上述的子载波分配方案为基础，有三种不同的实现方案，分别描述如下，为描述方便，以2根天线为例进行描述，一根天线对应一个流，所以下述三种实现方案中都是针对2个流的描述，其他多流的情况可以参照2个流的情况得出，在此不再赘述。其中，一个流传输一个OFDM符号，
第一种实现方案，设保留子载波对应的信道信息是已知的，此时处理方式如下：
每个流单独进行降峰均比处理，得到每个保留子载波上传输的相位因子，并进行传输，其中，所有的流使用相同的保留子载波传输相位因子；
在接收端采用MIMO的解调方式得出每个流在每一块上的相位因子；
后续的操作如单流(或如上文针对一个OFDM符号的情况)。
举例来说，发送端有2个天线进行信号发送，接收端有2根天线接收，有两个流分别传输OFDM符号，其中，两个流上的OFDM符号上的子载波都分为4块。以第一块为例，第一个流对应的相位因子为
Figure PCTCN2015072695-appb-000092
，第二个流对应的相位因子为
Figure PCTCN2015072695-appb-000093
，其中，φ11表示第一个流在第一分块上的相位，φ21表示第二个流在第一分块上的相位。同样取第一分块上的4个子载波(-498，-444，-390，-336)来同时传输这两个相位因子。以-498个子载波上承载的数据而言，接收到的信号可以表示为：
Figure PCTCN2015072695-appb-000094
其中
Figure PCTCN2015072695-appb-000095
表示第k1＝1，2根天线接收到的数据，k2表示子载波序号。
Figure PCTCN2015072695-appb-000096
表示在子载波k2上，流k3＝1，2到第k1＝1，2天线的信道。z为噪声。
根据上述公式，可以采用现有的MIMO处理方法解出在-498子载上传输的相位因子的估值。依此类推，可以求出在(-444，-390，-336)子载波上传输的两个相位因子的估值。将这四个子载波上传输的两个相位因子的估值进行合并后，基本上可以无差错地恢复出相位因子的信息。剩余3个块的处理类似。
上述的描述中保留子载波传输的是相位因子本身的信息，保留子载波传输的也可以是对相位因子进行调制(如QPSK)后的信息、对相位因子进行差分调制后的信息、对相位因子进行能量调制后的信息、对相位因子进行编码和调制后的信息、对相位因子进行编码和差分调制的信息或对相位因子进行编码和能量调制的信息等等。
第二种实现方案，设保留子载波对应的信道信息是未知的，此时处理方式如下：
每个流单独进行降峰均比处理，得到每个保留子载波上传输的相位因子；
每个流分配一组保留子载波传输相位因子，其中，在每个分块中一共有 四对保留子载波，其中一组保留子载波是指这四对保留子载波中分别选一个出来共四个子载波为一组，另外四个子载波为一组，其他分块的情况类似，例如一组子载波(-498，-444，-390，-336)和另外一组子载波(-497，-443，-389，-335)；
后续的操作如单流(或如上文针对一个OFDM符号的情况)。
其中，每个流分配不同的保留子载波传输相位因子。
举例来说，发送端有2个天线进行信号发送，接收端有2根天线接收，有两个流分别传输OFDM符号，其中，两个流上的OFDM符号上的子载波都分为4块。以第一块为例，第一个流对应的相位因子为
Figure PCTCN2015072695-appb-000097
，第二个流对应的相位因子为
Figure PCTCN2015072695-appb-000098
，其中，φ11表示第一个流在第一分块上的相位，φ21表示第二个流在第一分块上的相位。选取第一分块上的4个保留子载波(-498，-444，-390，-336)来同时传输来传输第一个流对应的相位因子信息，以另四个保留子波来传输(-497，-443，-389，-335)第二个流对应的相位因子信息。具体的传输方法可以参见前面的实施例，例如传输方式1、2、3等，可以采用直接传输相位因子的方式，传输对相位因子进行调制(如QPSK)后的信息，传输对相位因子进行差分调制后的信息，传输相位因子进行能量调制后的信息，传输对相位因子进行编码和调制后的信息，传输对相位因子进行编码和差分调制的信息，传输对相位因子进行编码和能量调制的信息。
第三种实现方案，所有流统一进行降低PAPR，具体处理方法如下：
所有流共同进行降峰均比处理，得到每个保留子载波上传输的相位因子信息；
所有流在保留子载波上传输相同的信息。
后续的操作如单流(或如上文针对一个OFDM符号的情况)。
同样以发送端有2个流发送为例，OFDM符号上的子载波依然分为4块，每一块对应的相位因子为
Figure PCTCN2015072695-appb-000099
和
Figure PCTCN2015072695-appb-000100
。确定的4个相位因子使得两个流发送的2个OFDM符号的峰均比都最小(或两个峰均比的和最小)。同样，取第一块上的4个保留子载波(-498，-444，-390，-336)来同时传输第一个流对应的相位因子信息，2个流在这4个子载波上传输相同的相位因子信息。传输的相位因子信息包括如下几种方式：直接传输相位因子、传输对相位因子进行调制(如QPSK)后的信息、传输对相位因子进行差分调制后的 信息、传输相位因子进行能量调制后的信息、传输对相位因子进行编码和调制后的信息、传输对相位因子进行编码和差分调制的信息或传输对相位因子进行编码和能量调制的信息，其它块依此类推。
相应于上面的方法实施例，本发明实施例还提供一种降低峰均比的装置，所述装置应用于无线保真WiFi***，如图12所示：包括：
划分模块1201，用于将承载待传输数据的正交频分复用OFDM符号的子载波进行划分，得到多个分块；
确定模块1202，用于确定多个分块对应的多个相位因子，其中，多个相位因子用来降低OFDM符号的峰均比；
传输模块1203，用于利用OFDM符号的特定子载波传输多个相位因子，多个分块中的每个分块上传输的数据分别乘以对应的相位因子，并进行传输。
其中涉及到的一些技术特征，例如：相位因子、特定子载波、子载波划分、峰均比和降低峰均比的方法等，和上述方法实施例涉及到的一些技术特征类似或对应，本实施例不再进行重复说明。
相应于上面的方法实施例，本发明实施例还提供一种降低峰均比的设备，所述设备应用于无线保真WiFi***，如图13所示，包括：
处理器1301、存储器1302、发射机1304及总线1303，其中处理器1301、存储器1302及发射机1304通过总线1303连接进行数据传输，存储器1302用于存储处理器1301处理的数据；
处理器1301用于将承载待传输数据的正交频分复用OFDM符号的子载波进行划分，得到多个分块；确定多个分块对应的多个相位因子，多个相位因子用来降低所述OFDM符号的峰均比；
发射机1304用于利用OFDM符号的特定子载波传输多个相位因子；多个分块中的每个分块乘以对应的相位因子，并进行传输。
其中涉及到的一些技术特征，例如：相位因子、特定子载波、子载波划分、峰均比和降低峰均比的方法等，和上述方法实施例涉及到的一些技术特征类似或对应，本实施例不再进行重复说明。
相应于上面的方法实施例，本发明实施例还提供一种降低峰均比的***， 所述***应用于无线保真WiFi***，包括：图12提供的降低峰均比的装置或图13提供的降低峰均比的设备。
其中涉及到的一些技术特征，例如：相位因子、特定子载波、子载波划分、峰均比和降低峰均比的方法等，和上述方法实施例涉及到的一些技术特征类似或对应，本实施例不再进行重复说明。
相应于上面的方法实施例，本发明实施例还提供一种降低峰均比的方法，所述方法应用于无线保真WiFi***，如图14所示：包括：
步骤1401：接收正交频分复用OFDM符号，其中，OFDM符号的子载波划分为多个分块，多个分块对应多个相位因子，所多个相位因子用来降低OFDM符号的峰均比，OFDM符号的特定子载波承载的是多个相位因子，多个分块中的每个分块上承载的是乘以对应的相位因子的数据；
步骤1402：根据特定子载波承载的信号，得到多个相位因子；
步骤1403：根据相位因子和多个分块，得到OFDM符号传输的数据。
可选地，特定子载波为保留子载波，其中，保留子载波为OFDM符号的子载波中预留的子载波；
其中，根据特定子载波承载的信号，得到多个相位因子包括：
对特定子载波承载的信号进行解调，得到相位因子信息；
将相位因子信息转出成相位因子。
进一步地，在对特定子载波承载的信号进行解调之后，根据特定子载波承载的信号，得到多个相位因子还包括：
对解调后的数据进行解码，得到相位因子信息。
其中，将多个相位因子信息转换成相位因子包括：
按照多个相位因子信息和相位因子之间的映射规则进行转换，其中，映射规则包括表格映射或公式映射。
可选地，特定子载波为导频子载波，其中，导频子载波承载的是多个相位因子中对应的相位因子和导频信号的乘积。
进一步地，多个相位因子的确定方法包括：
多个相位因子从有限集合中取值，以使得多个分块乘以多个相位因子后的PAPR最小化。
其中，有限集合为
Figure PCTCN2015072695-appb-000101
或
Figure PCTCN2015072695-appb-000102
或其他类似变形。
进一步的，本发明实施例提供的方法还包括：
接收802.11标准帧，其中，802.11标准帧的信令字段或服务字段中增加额外的指示比特或复用已有比特，其中，指示比特或已有比特用来通知接收端是否采用了本发明提供的降低峰均比的方法及分块的块数；
根据指示比特或复用的已有比特，确定是否采用本发明提供的降低峰均比的方法及分块的块数。
其中涉及到的一些技术特征，例如：相位因子、特定子载波、子载波划分、峰均比和降低峰均比的方法等，和上述方法实施例涉及到的一些技术特征类似或对应，本实施例不再进行重复说明。
相应于上面的方法实施例，本发明实施例还提供一种降低峰均比的装置，所述方法应用于无线保真WiFi***，如图15所示：包括：
接收模块1501，用于接收正交频分复用OFDM符号，其中，OFDM符号的子载波划分为多个分块，多个分块对应多个相位因子，多个相位因子用来降低OFDM符号的峰均比，OFDM符号的特定子载波承载的是多个相位因子，多个分块中的每个分块上承载的是乘以对应的相位因子的数据；
获取模块1502，用于根据特定子载波承载的信号，得到多个相位因子；
恢复模块1503，用于根据相位因子和所述多个分块，得到OFDM符号传输的数据。
其中涉及到的一些技术特征，例如：相位因子、特定子载波、子载波划分、峰均比和降低峰均比的方法等，和上述方法实施例涉及到的一些技术特征类似或对应，本实施例不再进行重复说明。
相应于上面的方法实施例，本发明实施例还提供一种降低峰均比的设备，所述设备应用于无线保真WiFi***，如图16所示，包括：处理器1601、存储器1602、接收机1604及总线1603，其中处理器1601、存储器1602及接收机1604通过总线1603连接进行数据传输，存储器1602用于存储处理器处理1601的数据；
接收机1604，用于接收正交频分复用OFDM符号，其中，OFDM符号的子载波划分为多个分块，多个分块对应多个相位因子，多个相位因子用来降低OFDM符号的峰均比，OFDM符号的特定子载波承载的是多个相位因子， 多个分块中的每个分块上承载的是乘以对应的相位因子的数据；
处理器1601，用于根据特定子载波承载的信号，得到多个相位因子；根据相位因子和所述多个分块，得到OFDM符号传输的数据。
其中涉及到的一些技术特征，例如：相位因子、特定子载波、子载波划分、峰均比和降低峰均比的方法等，和上述方法实施例涉及到的一些技术特征类似或对应，本实施例不再进行重复说明。
相应于上面的方法实施例，本发明实施例还提供一种降低峰均比的***，所述***应用于无线保真WiFi***，包括：图15提供的降低峰均比的装置或图16提供的降低峰均比的设备。
其中涉及到的一些技术特征，例如：相位因子、特定子载波、子载波划分、峰均比和降低峰均比的方法等，和上述方法实施例涉及到的一些技术特征类似或对应，本实施例不再进行重复说明。
应理解地，在本发明的各种实施例中，上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本发明实施例的实施过程构成任何限定。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、计算机软件或者二者的结合来实现，为了清楚地说明硬件和软件的可互换性，在上述说明中已经按照功能一般性地描述了各示例的组成及步骤。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本发明的范围。
所属领域的技术人员可以清楚地了解到，为了描述的方便和简洁，上述描述的***、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个***，或 一些特征可以忽略，或不执行。另外，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口、装置或单元的间接耦合或通信连接，也可以是电的，机械的或其它的形式连接。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本发明实施例方案的目的。
另外，在本发明各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以是两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。具体的，可以借助软件加必需的通用硬件的方式来实现，通用硬件包括通用集成电路、通用CPU(英文：Central Processing Unit，中文：中央处理器)、通用数字信号处理器(英文：Digital Signal Processor，简称：DSP)、现场可编程门阵列(英文：Field Programming Gate Array，简称：FPGA)、可编程逻辑器件(英文：Programmable Logical Device，简称：PLD)、通用存储器、通用元器件等，当然也可以通过专用硬件包括专用集成电路(英文：Application Specific Integrated Circuit，简称ASIC)、专用CPU、专用存储器、专用元器件等来实现。
所述集成的单元如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本发明的技术方案本质上或者说对现有技术做出贡献的部分，或者该技术方案的全部或部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本发明各个实施例所述方法的全部或部分步骤。而前述的存储介质包括：U盘、移动硬盘、只读存储器(英文：Read Only Memory，简称为ROM)、随机存取存储器(英文：Random Access Memory，简称为RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
软件或指令还可以通过传输介质来传输。例如，如果使用同轴电缆、光纤光缆、双绞线、数字用户线(英文：Digital Subscriber Line,简称：DSL)或者无线技术(如红外线、无线电和微波)从网站、服务器或其它远程源传输软件，那么同轴电缆、光纤光缆、双绞线、DSL或者无线技术(如红外线、无线电和 微波))包括在传输介质的定义中。
以上所述，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到各种等效的修改或替换，这些修改或替换都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以权利要求的保护范围为准。

Claims (65)

  1. 一种降低峰均比的方法，所述方法应用于无线保真WiFi***，其特征在于，包括：
    将承载待传输数据的正交频分复用OFDM符号的子载波进行划分，得到多个分块；
    确定多个分块对应的多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比；
    利用所述OFDM符号的特定子载波传输所述多个相位因子；
    将所述多个分块中的每个分块上传输的数据乘以对应的相位因子，并进行传输。
  2. 根据权利要求1所述的方法，其特征在于，
    所述特定子载波为保留子载波，所述保留子载波为所述OFDM符号的子载波中预留的子载波；
    所述利用所述OFDM符号的特定子载波传输所述多个相位因子包括：
    将所述多个相位因子转换成相位因子信息；
    对所述相位因子信息进行调制，得到调制后的数据；
    将所述调制后的数据承载到所述保留子载波上进行传输，其中，所述保留子载波承载的调制后的数据不乘以相位因子。
  3. 根据权利要求2所述的方法，其特征在于，在对所述相位因子信息进行调制之前，所述利用所述OFDM符号的特定子载波传输所述多个相位因子还包括：
    对所述相位因子的信息进行编码，得到编码后的数据；
    所述对所述相位因子信息进行调制包括：
    对所述编码后的数据进行调制。
  4. 根据权利要求3所述的方法，其特征在于，
    所述编码的方式包括：块编码、1/2的咬尾卷积码、CRC编码、Reed-Muller编码或奇偶校验编码。
  5. 根据权利要求2至4任一项所述的方法，其特征在于，
    所述调制的方式包括：QPSK调制、DQPSK调制或能量调制。
  6. 根据权利要求2至5任一项所述的方法，其特征在于，所述将所述调 制后的数据承载到所述保留子载波上进行传输之前，所述方法还包括：
    对所述调制后的数据进行重复，得到重复后的数据；
    所述将调制后的数据承载到所述保留子载波上进行传输包括：
    将所述重复后的数据承载到所述保留子载波上进行传输。
  7. 根据权利要求2至6任一项所述的方法，其特征在于，
    所述将所述多个相位因子转换成相位因子信息包括：
    按照所述多个相位因子和所述相位因子信息之间的映射规则进行转换，其中，映射规则包括表格映射或公式映射。
  8. 根据权利要求1至7任一项所述的方法，其特征在于，
    所述保留子载波分布在所述OFDM符号的整个频域范围内；
    所述保留子载波的分布方式按照相邻的保留子载波间的序号差的方差最小的规则进行分布。
  9. 根据权利要求1至8任一项所述的方法，其特征在于，
    所述利用所述OFDM符号的特定子载波传输所述多个相位因子包括：
    利用所述多个分块的保留子载波传输所述多个相位因子；
    或者
    利用所述多个分块中的每一个分块的保留子载波传输每一个分块对应的相位因子。
  10. 根据权利要求1所述的方法，其特征在于，
    所述特定子载波为导频子载波；
    所述利用所述OFDM符号的特定子载波传输所述多个相位因子包括：
    将所述多个相位因子承载到所述导频子载波上进行传输，其中，所述导频子载波承载所述多个相位因子中对应的相位因子和导频信号的乘积。
  11. 根据权利要求1至10任一项所述的方法，其特征在于，
    所述确定所述多个分块对应的多个相位因子包括：
    所述多个相位因子从有限集合中取值，以使得所述多个分块乘以所述多个相位因子后的PAPR最小化。
  12. 根据权利要求11所述的方法，其特征在于，
    所述有限集合为
    Figure PCTCN2015072695-appb-100001
    或
    Figure PCTCN2015072695-appb-100002
  13. 根据权利要求1至12任一项所述的方法，其特征在于，所述方法还包括：
    在802.11标准帧结构的信令字段或服务字段中增加额外的指示比特或复用已有比特，所述指示比特或已有比特用来通知接收端是否采用了本发明提供的降低峰均比的方法及分块的块数。
  14. 一种降低峰均比的装置，所述装置应用于无线保真WiFi***，其特征在于，包括：
    划分模块，用于将承载待传输数据的正交频分复用OFDM符号的子载波进行划分，得到多个分块；
    确定模块，用于确定多个分块对应的多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比；
    传输模块，用于利用所述OFDM符号的特定子载波传输所述多个相位因子，将所述多个分块中的每个分块乘以对应的相位因子，并进行传输。
  15. 根据权利要求14所述的装置，其特征在于，
    所述特定子载波为保留子载波，所述保留子载波为所述OFDM符号的子载波中预留的子载波；
    所述传输模块包括：
    转换模块，用于将所述多个相位因子转换成相位因子信息；
    调制模块，用于对所述相位因子信息进行调制，得到调制后的数据；
    第一承载模块，用于将所述调制后的数据承载到所述保留子载波上进行传输，其中，所述保留子载波承载的调制后的数据不乘以相位因子。
  16. 根据权利要求15所述的装置，其特征在于，所述传输模块还包括：
    编码模块，用于对所述相位因子的信息进行编码，得到编码后的数据；
    所述对所述相位因子信息进行调制包括：
    对所述编码后的数据进行调制。
  17. 根据权利要求16所述的装置，其特征在于，
    所述编码的方式包括：块编码、1/2的咬尾卷积码、CRC编码、Reed-Muller编码或奇偶校验编码。
  18. 根据权利要求15至17任一项所述的装置，其特征在于，
    所述调制的方式包括：QPSK调制、DQPSK调制或能量调制。
  19. 根据权利要求15至18任一项所述的装置，其特征在于，所述传输模块还包括：
    重复模块，用于对所述调制后的数据进行重复，得到重复后的数据；
    所述将调制后的数据承载到所述保留子载波上进行传输包括：
    将所述重复后的数据承载到所述保留子载波上进行传输。
  20. 根据权利要求15至19任一项所述的装置，其特征在于，
    所述将所述多个相位因子转换成相位因子信息包括：
    按照所述多个相位因子和所述相位因子信息之间的映射规则进行转换，其中，映射规则包括表格映射或公式映射。
  21. 根据权利要求14至20任一项所述的装置，其特征在于，
    所述保留子载波分布在所述OFDM符号的整个频域范围内；
    所述保留子载波的分布方式按照相邻的保留子载波间的序号差的方差最小的规则进行分布。
  22. 根据权利要求14至21任一项所述的装置，其特征在于，
    所述利用所述OFDM符号的特定子载波传输所述多个相位因子包括：
    利用所述多个分块的保留子载波传输所述多个相位因子；
    或者
    利用所述多个分块中的每一个分块的保留子载波传输每一个分块对应的相位因子。
  23. 根据权利要求14所述的装置，其特征在于，
    所述特定子载波为导频子载波；
    所述传输模块包括：
    第二承载模块，用于将所述多个相位因子承载到所述导频子载波上进行传输，其中，所述导频子载波承载所述多个相位因子中对应的相位因子和导频信号的乘积。
  24. 根据权利要求14至23任一项所述的装置，其特征在于，
    所述确定所述多个分块对应的多个相位因子包括：
    所述多个相位因子从有限集合中取值，以使得所述多个分块乘以所述多个相位因子后的PAPR最小化。
  25. 根据权利要求24所述的装置，其特征在于，
    所述有限集合为
    Figure PCTCN2015072695-appb-100003
    或
    Figure PCTCN2015072695-appb-100004
  26. 根据权利要求14至25任一项所述的装置，其特征在于，
    所述装置为站点设备或接入点设备。
  27. 一种降低峰均比的设备，所述设备应用于无线保真WiFi***，其特 征在于，包括：处理器、存储器、发射机及总线，其中所述处理器、存储器及发射机通过所述总线连接进行数据传输，所述存储器用于存储所述处理器处理的数据；
    所述处理器用于将承载待传输数据的正交频分复用OFDM符号的子载波进行划分，得到多个分块；确定多个分块对应的多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比；
    所述发射机用于利用所述OFDM符号的特定子载波传输所述多个相位因子；将所述多个分块中的每个分块乘以对应的相位因子，并进行传输。
  28. 根据权利要求27所述的设备，其特征在于，
    所述特定子载波为保留子载波，所述保留子载波为所述OFDM符号的子载波中预留的子载波；
    所述利用所述OFDM符号的特定子载波传输所述多个相位因子包括：
    将所述多个相位因子转换成相位因子信息；
    对所述相位因子信息进行调制，得到调制后的数据；
    将所述调制后的数据承载到所述保留子载波上进行传输，其中，所述保留子载波承载的调制后的数据不乘以相位因子。
  29. 根据权利要求28所述的设备，其特征在于，在对所述相位因子信息进行调制之前，所述利用所述OFDM符号的特定子载波传输所述多个相位因子还包括：
    对所述相位因子的信息进行编码，得到编码后的数据；
    所述对所述相位因子信息进行调制包括：
    对所述编码后的数据进行调制。
  30. 根据权利要求29所述的设备，其特征在于，
    所述编码的方式包括：块编码、1/2的咬尾卷积码、CRC编码、Reed-Muller编码或奇偶校验编码。
  31. 根据权利要求28至30任一项所述的设备，其特征在于，
    所述调制的方式包括：QPSK调制、DQPSK调制或能量调制。
  32. 根据权利要求28至31任一项所述的设备，其特征在于，所述发射机还用于对所述调制后的数据进行重复，得到重复后的数据；
    所述将调制后的数据承载到所述保留子载波上进行传输包括：
    将所述重复后的数据承载到所述保留子载波上进行传输。
  33. 根据权利要求28至32任一项所述的设备，其特征在于，
    所述将所述多个相位因子转换成相位因子信息包括：
    按照所述多个相位因子和所述相位因子信息之间的映射规则进行转换，其中，映射规则包括表格映射或公式映射。
  34. 根据权利要求27至33任一项所述的设备，其特征在于，
    所述保留子载波分布在所述OFDM符号的整个频域范围内；
    所述保留子载波的分布方式按照相邻的保留子载波间的序号差的方差最小的规则进行分布。
  35. 根据权利要求27至34任一项所述的设备，其特征在于，
    所述利用所述OFDM符号的特定子载波传输所述多个相位因子包括：
    利用所述多个分块的保留子载波传输所述多个相位因子；
    或者
    利用所述多个分块中的每一个分块的保留子载波传输每一个分块对应的相位因子。
  36. 根据权利要求27所述的设备，其特征在于，
    所述特定子载波为导频子载波；
    所述利用所述OFDM符号的特定子载波传输所述多个相位因子包括：
    将所述多个相位因子承载到所述导频子载波上进行传输，其中，所述导频子载波承载所述多个相位因子中对应的相位因子和导频信号的乘积。
  37. 根据权利要求27至36任一项所述的设备，其特征在于，
    所述确定所述多个分块对应的多个相位因子包括：
    所述多个相位因子从有限集合中取值，以使得所述多个分块乘以所述多个相位因子后的PAPR最小化。
  38. 根据权利要求37所述的设备，其特征在于，
    所述有限集合为
    Figure PCTCN2015072695-appb-100005
    或
    Figure PCTCN2015072695-appb-100006
  39. 根据权利要求27至38任一项所述的设备，其特征在于，
    所述设备为站点设备或接入点设备。
  40. 一种降低峰均比的***，所述***应用于无线保真WiFi***，其特征在于，
    所述***包括权利要求14至26任一项所述的装置或者权利要求37至39任一项所述的设备。
  41. 一种降低峰均比的方法，所述方法应用于无线保真WiFi***，其特征在于，包括：
    接收正交频分复用OFDM符号，其中，所述OFDM符号的子载波划分为多个分块，所述多个分块对应多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比，所述OFDM符号的特定子载波承载的是所述多个相位因子，所述多个分块中的每个分块上承载的是乘以对应的相位因子的数据；
    根据所述特定子载波承载的信号，得到所述多个相位因子；
    根据所述相位因子和所述多个分块，得到所述OFDM符号传输的数据。
  42. 根据权利要求41所述的方法，其特征在于，
    所述特定子载波为保留子载波，所述保留子载波为所述OFDM符号的子载波中预留的子载波；
    所述根据所述特定子载波承载的信号，得到所述多个相位因子包括：
    对所述特定子载波承载的信号进行解调，得到相位因子信息；
    将所述相位因子信息转出成相位因子。
  43. 根据权利要求42所述的方法，其特征在于，在对所述特定子载波承载的信号进行解调之后，所述根据所述特定子载波承载的信号，得到所述多个相位因子还包括：
    对所述解调后的数据进行解码，得到相位因子信息。
  44. 根据权利要求42或43所述的设备，其特征在于，
    所述将所述多个相位因子信息转换成相位因子包括：
    按照所述多个相位因子信息和所述相位因子之间的映射规则进行转换，其中，映射规则包括表格映射或公式映射。
  45. 根据权利要求41所述的方法，其特征在于，
    所述特定子载波为导频子载波，其中，所述导频子载波承载的是所述多个相位因子中对应的相位因子和导频信号的乘积。
  46. 根据权利要求41至45任一项所述的方法，其特征在于，
    所述多个相位因子的确定方法包括：
    所述多个相位因子从有限集合中取值，以使得所述多个分块乘以所述多个相位因子后的PAPR最小化。
  47. 根据权利要求46所述的方法，其特征在于，
    所述有限集合为
    Figure PCTCN2015072695-appb-100007
    或
    Figure PCTCN2015072695-appb-100008
  48. 根据权利要求41至47任一项所述的方法，其特征在于，所述方法还包括：
    接收802.11标准帧，其中，所述802.11标准帧的信令字段或服务字段中增加额外的指示比特或复用已有比特，所述指示比特或已有比特用来通知接收端是否采用了本发明提供的降低峰均比的方法及分块的块数；
    根据所述指示比特或复用的已有比特，确定是否采用本发明提供的降低峰均比的方法及分块的块数。
  49. 一种降低峰均比的装置，所述装置应用于无线保真WiFi***，其特征在于，包括：
    接收模块，用于接收正交频分复用OFDM符号，其中，所述OFDM符号的子载波划分为多个分块，所述多个分块对应多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比，所述OFDM符号的特定子载波承载的是所述多个相位因子，所述多个分块中的每个分块上承载的是乘以对应的相位因子的数据；
    获取模块，用于根据所述特定子载波承载的信号，得到所述多个相位因子；
    恢复模块，用于根据所述相位因子和所述多个分块，得到所述OFDM符号传输的数据。
  50. 根据权利要求49所述的装置，其特征在于，
    所述特定子载波为保留子载波，所述保留子载波为所述OFDM符号的子载波中预留的子载波；
    所述根据所述特定子载波承载的信号，得到所述多个相位因子包括：
    对所述特定子载波承载的信号进行解调，得到相位因子信息；
    将所述相位因子信息转出成相位因子。
  51. 根据权利要求50所述的装置，其特征在于，所述获取模块还包括：
    解调模块，用于对所述解调后的数据进行解码，得到相位因子信息。
  52. 根据权利要求50或51所述的装置，其特征在于，
    所述将所述多个相位因子信息转换成相位因子包括：
    按照所述多个相位因子信息和所述相位因子之间的映射规则进行转换，其中，映射规则包括表格映射或公式映射。
  53. 根据权利要求49所述的装置，其特征在于，
    所述特定子载波为导频子载波，其中，所述导频子载波承载的是所述多个相位因子中对应的相位因子和导频信号的乘积。
  54. 根据权利要求49至53任一项所述的装置，其特征在于，
    所述多个相位因子的确定方法包括：
    所述多个相位因子从有限集合中取值，以使得所述多个分块乘以所述多个相位因子后的PAPR最小化。
  55. 根据权利要求54所述的装置，其特征在于，
    所述有限集合为
    Figure PCTCN2015072695-appb-100009
    或
    Figure PCTCN2015072695-appb-100010
  56. 根据权利要求49至55任一项所述的装置，其特征在于，
    所述接收模块还用于接收802.11标准帧，其中，所述802.11标准帧的信令字段或服务字段中增加额外的指示比特或复用已有比特，所述指示比特或已有比特用来通知接收端是否采用了本发明提供的降低峰均比的方法及分块的块数；
    所述装置还包括：确定模块，用于根据所述指示比特或复用的已有比特，确定是否采用本发明提供的降低峰均比的方法及分块的块数。
  57. 一种降低峰均比的设备，所述设备应用于无线保真WiFi***，其特征在于，包括：处理器、存储器、接收机及总线，其中所述处理器、存储器及接收机通过所述总线连接进行数据传输，所述存储器用于存储所述处理器处理的数据；
    接收机，用于接收正交频分复用OFDM符号，其中，所述OFDM符号的子载波划分为多个分块，所述多个分块对应多个相位因子，所述多个相位因子用来降低所述OFDM符号的峰均比，所述OFDM符号的特定子载波承载的是所述多个相位因子，所述多个分块中的每个分块上承载的是乘以对应的相位因子的数据；
    处理器，用于根据所述特定子载波承载的信号，得到所述多个相位因子；根据所述相位因子和所述多个分块，得到所述OFDM符号传输的数据。
  58. 根据权利要求57所述的设备，其特征在于，
    所述特定子载波为保留子载波，所述保留子载波为所述OFDM符号的子载波中预留的子载波；
    所述根据所述特定子载波承载的信号，得到所述多个相位因子包括：
    对所述特定子载波承载的信号进行解调，得到相位因子信息；
    将所述相位因子信息转出成相位因子。
  59. 根据权利要求58所述的设备，其特征在于，所述处理器还用于对所述解调后的数据进行解码，得到相位因子信息。
  60. 根据权利要求58或59所述的设备，其特征在于，
    所述将所述多个相位因子信息转换成相位因子包括：
    按照所述多个相位因子信息和所述相位因子之间的映射规则进行转换，其中，映射规则包括表格映射或公式映射。
  61. 根据权利要求57所述的设备，其特征在于，
    所述特定子载波为导频子载波，其中，所述导频子载波承载的是所述多个相位因子中对应的相位因子和导频信号的乘积。
  62. 根据权利要求57至61任一项所述的设备，其特征在于，
    所述多个相位因子的确定方法包括：
    所述多个相位因子从有限集合中取值，以使得所述多个分块乘以所述多个相位因子后的PAPR最小化。
  63. 根据权利要求62所述的设备，其特征在于，
    所述有限集合为
    Figure PCTCN2015072695-appb-100011
    或
    Figure PCTCN2015072695-appb-100012
  64. 根据权利要求57至63任一项所述的设备，其特征在于，
    所述接收机还用于接收802.11标准帧，其中，所述802.11标准帧的信令字段或服务字段中增加额外的指示比特或复用已有比特，所述指示比特或已有比特用来通知接收端是否采用了本发明提供的降低峰均比的方法及分块的块数；
    所述处理器还用于根据所述指示比特或复用的已有比特，确定是否采用本发明提供的降低峰均比的方法及分块的块数。
  65. 一种降低峰均比的***，所述***应用于无线保真WiFi***，其特征在于，
    所述***包括权利要求49至56任一项所述的装置或者权利要求57至64任一项所述的设备。
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