WO2017148189A1 - 生成ofdm时域信号的方法和装置 - Google Patents

生成ofdm时域信号的方法和装置 Download PDF

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Publication number
WO2017148189A1
WO2017148189A1 PCT/CN2016/107530 CN2016107530W WO2017148189A1 WO 2017148189 A1 WO2017148189 A1 WO 2017148189A1 CN 2016107530 W CN2016107530 W CN 2016107530W WO 2017148189 A1 WO2017148189 A1 WO 2017148189A1
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Prior art keywords
domain signal
time domain
ofdm
point
ofdm time
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PCT/CN2016/107530
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English (en)
French (fr)
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胡宇鹏
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华为技术有限公司
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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
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2691—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation involving interference determination or cancellation
    • 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

Definitions

  • the present invention relates to the field of data processing technologies, and in particular, to a method and apparatus for generating a time domain signal of Orthogonal Frequency Division Multiplexing (OFDM).
  • OFDM Orthogonal Frequency Division Multiplexing
  • the method for generating an OFDM time domain signal by the transmitting end includes: the transmitting end maps the data onto the subcarrier to generate an OFDM frequency domain signal; and then performs an inverse Fourier transform of the preset sampling points on the OFDM frequency domain signal to generate a preset.
  • the OFDM time domain signal of the number of samples.
  • the guard interval may be a cyclic prefix (English full name: cyclic prefix, English abbreviation: CP).
  • the period of the OFDM time domain symbol in the OFDM time domain signal obtained according to the above method is long, and the longer the period of the OFDM time domain symbol, the greater the influence of the pulse interference during the transmission from the transmitter to the receiving end.
  • Embodiments of the present invention provide a method and apparatus for generating an OFDM time domain signal to effectively combat impulse interference.
  • a method for generating an OFDM time domain signal includes: mapping data to subcarriers in a target set to generate an OFDM frequency domain signal;
  • the OFDM frequency domain signal performs an inverse Fourier transform of the M point to generate an M point OFDM time domain signal; wherein the M is a preset sampling point number.
  • a second aspect provides an apparatus for generating an OFDM time domain signal, including: a mapping unit and a transform unit, where the mapping unit is configured to map data to subcarriers in the target set to generate an OFDM frequency domain signal; And performing an inverse Fourier transform of the M point on the OFDM frequency domain signal to generate an M point OFDM time domain signal; wherein the M is a preset sampling point number.
  • the target set includes any one of the following sets: the nkth subcarrier a set, a set of nk+1 subcarriers, a set of nk+2 subcarriers, ..., a set of nk+n-1 subcarriers; if the OFDM time domain signal of the M point is real OFDM a time domain signal, wherein the target set includes any one of the following: a set of nk subcarriers, a set of nk+n/2 subcarriers; the n is a factor of the M, n is greater than 1, and k is one or more integers in [0, (M/n)-1].
  • the obtained OFDM time domain signal includes n identical OFDM time domains. a symbol; if the data is mapped to a subcarrier in any of the following sets: a set of nk+1 subcarriers, a set of nk+2 subcarriers, ..., a nk+n-1 subcarrier
  • the aggregation may be performed by performing frequency transformation on the generated OFDM time domain signal, so that the frequency-converted OFDM time domain signal includes n identical OFDM time domain symbols.
  • n is greater than 1. Therefore, compared with the prior art, the period of the OFDM time domain symbol can be shortened, and thus it is possible to effectively combat the pulse interference.
  • an M-point OFDM time domain signal corresponds to a target set; different OFDM time domain signals may correspond to the same target set, or may correspond to different target sets.
  • different OFDM time domain signals may correspond to the same target set, or may correspond to different target sets.
  • the specific implementation is not limited to this.
  • the method may further include: receiving the narrowband interference detection result; The narrowband interference detection result determines the target set.
  • the apparatus provided by the second aspect may further include: a receiving unit and a determining unit; the receiving unit is configured to receive the narrowband interference detection result; and the determining unit is configured to determine the target set according to the narrowband interference detection result.
  • This optional implementation is effective in avoiding narrowband interference.
  • the method may further include: adding a guard interval for the OFDM time domain signal, specifically: adding a guard interval before the OFDM time domain signal of the M point.
  • the apparatus in the foregoing second aspect may further include an adding unit, configured to add a guard interval to the OFDM time domain signal of the M point.
  • a third aspect provides a method for generating an OFDM time domain signal, including: mapping data onto a subcarrier to obtain an OFDM frequency domain signal; and performing an inverse Fourier transform of the M/n point on the OFDM frequency domain signal, Obtaining an M/n point OFDM time domain signal; wherein, the M is a preset number of sampling points, the n is a factor of the M, and the n is greater than 1; then, the M/n point OFDM time domain signal is Copy n-1 times to obtain an OFDM time domain signal of M point.
  • a fourth aspect provides an apparatus for generating an OFDM time domain signal, including: a mapping unit, a transform unit, and a copy unit; wherein, the mapping unit is configured to map data to a subcarrier to obtain an OFDM frequency domain signal; and a transform unit, And performing an inverse Fourier transform of the M/n point on the OFDM frequency domain signal to obtain an M/n point OFDM time domain signal; wherein the M is a preset sampling point, and the n is the M a factor, the n is greater than 1; a copy unit, configured to copy the M/n point OFDM time domain signal by n-1 times to obtain an OFDM time domain signal of the M point.
  • n are the same
  • the OFDM time domain signal of the M/n point is spliced into an M point OFDM time domain signal, so that the OFDM time domain signal of the M/n point can be regarded as an OFDM time domain symbol in the M point OFDM time domain signal; It can be seen that, in the case that the preset sampling rate M is constant, the embodiment of the present invention shortens the period of the OFDM time domain symbol compared with the prior art, and thus can effectively combat the pulse interference.
  • the method may further include: A guard interval is added before the first M/n point OFDM time domain signal in the OFDM time domain signal of the M point.
  • the apparatus may further include: adding, configured to: add protection before the first M/n point OFDM time domain signal in the OFDM time domain signal of the M point interval.
  • the specific filling content of the guard interval is not limited in the embodiment of the present invention, and may be implemented, for example, by any one of the prior art.
  • an embodiment of the present invention provides an apparatus for generating an OFDM time domain signal, the apparatus having the function of implementing the method provided by the foregoing first aspect.
  • the functions may be implemented by hardware or by corresponding software implemented by hardware.
  • the hardware or software includes one or more modules corresponding to the functions described above.
  • the apparatus includes a processor and a transceiver configured to support the apparatus to perform the corresponding functions of the method of the above first aspect.
  • the transceiver is used to support communication between the device and other devices.
  • the apparatus can also include a memory for coupling with the processor that retains the necessary program instructions and data in the apparatus.
  • an embodiment of the present invention provides a storage medium for storing computer software instructions used in the method of the above first aspect, including a program for performing all the actions in the first aspect described above.
  • an embodiment of the present invention provides an apparatus for generating an OFDM time domain signal, the apparatus having the function of implementing the method provided by the foregoing second aspect. Said function It can be implemented by hardware or by software.
  • the hardware or software includes one or more modules corresponding to the functions described above.
  • the apparatus includes a processor and a transceiver configured to support the apparatus to perform the corresponding functions in the method of the second aspect above.
  • the transceiver is used to support communication between the device and other devices.
  • the apparatus can also include a memory for coupling with the processor that retains the necessary program instructions and data in the apparatus.
  • an embodiment of the present invention provides a storage medium for storing computer software instructions used in the method of the second aspect, which includes a program for performing all the actions in the second aspect.
  • FIG. 1 is a schematic diagram of a format of an OFDM baseband signal according to an embodiment of the present invention
  • FIG. 2 is a flowchart of a method for generating an OFDM time domain signal according to an embodiment of the present invention
  • FIG. 3 is a schematic diagram of a format of an OFDM time domain signal provided in the prior art
  • FIG. 5 is a flowchart of another method for generating an OFDM time domain signal according to an embodiment of the present invention.
  • FIG. 6 is a schematic diagram of a format of an OFDM baseband signal according to an embodiment of the present invention.
  • FIG. 7 is a schematic structural diagram of an apparatus for generating an OFDM time domain signal according to an embodiment of the present disclosure
  • FIG. 8 is a schematic structural diagram of another apparatus for generating an OFDM time domain signal according to an embodiment of the present disclosure.
  • FIG. 9 is another apparatus for generating an OFDM time domain signal according to an embodiment of the present invention. Schematic diagram of the structure
  • FIG. 10 is a schematic structural diagram of another apparatus for generating an OFDM time domain signal according to an embodiment of the present invention.
  • FIG. 1 it is a schematic diagram of the format of an OFDM baseband signal.
  • the OFDM baseband signal is composed of an OFDM time domain signal and a CP corresponding to the OFDM time domain signal.
  • the length of the OFDM time domain signal is related to the preset number of sampling points and the sampling frequency; when the sampling frequency is constant, the larger the preset sampling point, the longer the length of the OFDM time domain signal, and the preset sampling point is determined according to the channel environment.
  • the length of the CP is determined by the maximum multipath delay of the channel.
  • the OFDM time domain signal of the preset sampling point obtained according to the above method contains only one OFDM time domain symbol. Therefore, the period of the OFDM time domain symbol thus obtained is long, which causes the OFDM time domain symbol to be greatly interfered by the pulse.
  • an embodiment of the present invention provides a method and apparatus for generating an OFDM time domain signal to effectively combat impulse interference.
  • the length herein refers to the length of the time domain, that is, the duration; for example, the length of the OFDM time domain symbol refers to the duration of the OFDM time domain symbol, and the length of the CP refers to the duration of the CP. Since the length is related to the sampling frequency and the number of sampling points, in the embodiment of the present invention, the sampling frequency domain is always constant. Therefore, the length of the sampling point can be used to represent the length. For example, if the length of the OFDM time domain signal is 1024 points, the length of the CP is At 264 points, the multipath length is 200 points.
  • the executor of the method for generating an OFDM time domain signal provided herein may be a transmitting end. Both the transmitting end and the receiving end may include but not limited to: a base station and a user equipment (English name: user equipment, English abbreviation: UE) Access point (English full name: access point, English abbreviation: AP). "Multiple" as used herein refers to two or more.
  • FIG. 2 is a flowchart of a method for generating an OFDM time domain signal according to an embodiment of the present invention.
  • the method shown in FIG. 2 includes the following steps S101-S102:
  • the transmitting end maps data to subcarriers in the target set to generate an OFDM frequency domain signal.
  • the transmitting end performs an inverse Fourier transform of the M point on the OFDM frequency domain signal to generate an OFDM time domain signal of the M point; where M is a preset sampling point number.
  • the target set includes any one of the following sets: a set of the nkth subcarrier, a set of the nk+1th subcarrier, and a nk+2 subcarrier. A set of constituents, ..., a set of nk+n-1 subcarriers.
  • the target set includes any one of the following sets: a set of the nkth subcarriers, and a set of the nk+n/2th subcarriers.
  • n is a factor of M, n is greater than 1; k is one or more integers in [0, (M/n)-1].
  • the OFDM time domain signal is a complex OFDM time domain signal
  • the inverse Fourier transform can be an inverse fast Fourier transform (English full name: IFFT), which is exemplified below. It should be noted that, for the sake of brevity, in the present embodiment, the following OFDM time domain signals refer to the OFDM time domain signals of M points.
  • the OFDM frequency domain signal needs to satisfy complex conjugate symmetry, wherein the complex conjugate symmetry requires that the 0th subcarrier and the M/2th subcarrier are real numbers, and The t-th subcarrier is complex conjugate with the Mt subcarrier, and t can take all integers in [1, M-1].
  • the complex conjugate symmetry requires that the mapped data on the 0th subcarrier and the 512th subcarrier are real numbers, and the first The subcarriers are symmetrically symmetric with the 1023th subcarrier, the second subcarrier is complex conjugate with the 1022th subcarrier, and the 510th subcarrier is complex conjugate with the 514th subcarrier.
  • k may be discontinuous, that is, in the embodiment of the present invention, k is taken.
  • the value is more flexible and can be set according to actual needs.
  • One OFDM time domain signal corresponds to one target set; different OFDM time domain signals may correspond to one target set or correspond to different target sets.
  • the first 1024-point OFDM time domain signal may correspond to a set of 4kth subcarriers
  • the second 1024th point The OFDM time domain signal may correspond to a set of 4k+1th subcarriers
  • the third 1024 point OFDM time domain signal may correspond to a set of 4kth subcarriers.
  • the OFDM time domain signal generated in S102 is composed of n identical OFDM time domain symbols, and the length of each OFDM time domain symbol is an M/n point.
  • the OFDM time domain signal in the prior art is composed of an M point OFDM time domain symbol.
  • FIG. 4 it is a schematic diagram of comparison between the prior art and the OFDM baseband signal in the embodiment of the present invention. 4 is an example in which the length of the CP is 256 points and the length of the OFDM time domain signal is 1024 points. Thus, the period of one OFDM time domain symbol in the prior art is 1024 points, as shown in FIG. 4 .
  • (a) As shown, the period of one OFDM time domain symbol in the embodiment of the present invention is 256 points, as shown in FIG. 4(b).
  • the OFDM time domain signal of the M point is frequency-converted by the receiving end, so that the transformed data is all on the nkth subcarrier, so that the transformed OFDM time domain signal is composed of n identical OFDM time domain symbols.
  • the length of each OFDM time domain symbol is the M/n point.
  • the OFDM time domain signal for which the receiving end performs frequency conversion is a time domain signal obtained after transmission through the power line channel.
  • the period of the OFDM time domain symbol is shortened compared to the prior art, and thus it is effective against impulse interference.
  • the adjacent two subcarriers with data mapped are separated by a certain number of subcarriers, and therefore, when the average power in the time domain is constant, the transmission is performed.
  • the terminal can use the transmission power of the sub-carriers to which the data is not mapped to the sub-carriers on which the data is mapped, so that the transmission power of each sub-carrier mapped with the data is increased by n times, thereby improving the receiving performance of the signal at the receiving end.
  • the transmit power of the subcarrier refers to the power used by the transmitting end to transmit data on one subcarrier.
  • the period of the OFDM time domain symbol should be as short as possible, and one implementation manner is: shortening when the multipath length is constant, that is, the length of the CP is constant.
  • the period of the OFDM time domain symbol thus, the data transmission efficiency is greatly reduced.
  • the sampling rate is 25 MHz (megahertz) and the preset sampling point is 1024; the length of the CP is 1/4 of the period of the OFDM time domain symbol, then 1024 points can be used to represent the period of the OFDM time domain symbol, with 256
  • the dot indicates the length of the CP, as shown in (a) of FIG.
  • the transmitting end in order to combat the attenuation and noise in the channel, the transmitting end generally needs to copy the data multiple times (for example, 4 times, 5 times, or 8 times, etc.), but these copies all occur in the frequency domain. That is, the frequency domain diversity processing is performed on the data.
  • the technical solution provided by the embodiment of the present invention may be understood as: copying the frequency domain of part or all times, in order to better compare the data with the prior art.
  • the time domain in the case where the total number of copies is the same, it is able to achieve the same effect of attenuation and noise in the anti-channel as in the prior art.
  • mapping data on the nk subcarriers provided by the implementation of the present invention can be understood as moving some or all times of the frequency domain copy to the time domain;
  • the technical solution on the other target set, after cooperating with the frequency transform operation, may be equivalent to shifting the copy in the frequency domain of part or all of the times to the time domain.
  • the transmitting end receives the narrowband interference detection result (specifically: the transmitting end receives the narrowband interference detection result sent by the receiving end); and then, according to the narrowband interference detection result, determining Target collection.
  • the specific implementation is not limited to this.
  • the narrowband interference detection result may be used to indicate at least one of the following information: which narrowband interferences are larger on the transmission band of the transmitting end and the receiving end, and which narrowbands are used.
  • the interference is small, the interference value on any one or more narrow bands, and the like.
  • the specific implementation manner of the method for obtaining the measurement result of the measurement of the narrowband interference is not limited in the embodiment of the present invention. For example, the method in the prior art can be used.
  • the transmitting end may determine the set of subcarriers with less interference as the target set according to the narrowband interference detection result.
  • the method may further include: determining, by the transmitting end, values of M and n.
  • M can be determined according to a channel environment
  • n can be determined according to the total number of times of data copying and the number of times of copying in the frequency domain. The larger the value of n, the better the effect against impulse interference, and the more effective avoidance of narrowband interference.
  • the method may further include: adding, by the transmitting end, a guard interval to the OFDM time domain signal of the M point, to obtain an OFDM baseband signal.
  • the guard interval is a CP
  • the sender may determine the length of the CP according to the maximum multipath delay of the channel, and then take a segment of the OFDM time domain signal of the M point that is equal to the length of the CP as a CP.
  • the content finally, adds the CP before the OFDM time domain signal at point M.
  • the guard interval is not limited to being a CP.
  • FIG. 5 it is a flowchart of another method for generating an OFDM time domain signal according to an embodiment of the present invention.
  • the method shown in Figure 5 includes:
  • S201 The transmitting end maps the data to the subcarriers to obtain an OFDM frequency domain signal.
  • S202 The transmitting end performs an inverse Fourier transform of the M/n point on the OFDM frequency domain signal to obtain an M/n point OFDM time domain signal.
  • M is a preset sampling point
  • n is a factor of M
  • n is greater than 1.
  • S203 The transmitting end copies the M/n point OFDM time domain signal by n-1 times to obtain an OFDM time domain signal of the M point.
  • the method may further include: adding, by the transmitting end, a guard interval for the OFDM time domain signal of the M point.
  • the guard interval is a CP
  • the sending end may determine the CP according to the maximum multipath delay of the channel, and take a piece of data of the tail of the OFDM time domain signal of the M point and the length of the CP as the content of the CP.
  • the CP is added before the OFDM time domain symbol of the first M/n point of the OFDM time domain signal of the point. An example is shown in (b) of FIG.
  • the technical solution provided in this embodiment can be understood as splicing OFDM time domain signals of n identical M/n points into one M-point OFDM time domain signal, so that the OFDM time domain signal of the M/n point can be regarded as An OFDM time domain symbol in the OFDM time domain signal of the M point; thus, it can be seen that, in the case that the preset sampling rate M is constant, the embodiment of the present invention shortens the period of the OFDM time domain symbol compared with the prior art. Therefore, it is effective against impulse interference.
  • this embodiment can ensure that the data transmission efficiency is constant while effectively combating the pulse interference.
  • the OFDM time domain signal of the M point in the embodiment shown in FIG. 5 includes n identical OFDM time domain symbols, which is a time domain diversity in a strict sense; in the embodiment shown in FIG. 2, only data is used.
  • the generated OFDM time domain signal of the M point is strictly time domain diversity.
  • the generated OFDM time domain signal needs to be frequency transformed. In order to achieve time domain diversity in a strict sense.
  • the data in the embodiment shown in FIG. 5 is mapped on the kth subcarrier, that is, according to the method in the prior art; the data in the embodiment shown in FIG. 2 is mapped. Any of the target sets provided above.
  • the transmitting end may also determine M according to the channel environment, and determine n according to the total number of times of data copying and the number of times of copying in the frequency domain.
  • n the total number of times of data copying and the number of times of copying in the frequency domain. The larger the value of n is, the shorter the period of the OFDM time domain symbol in the OFDM time domain signal is, and the better the effect against pulse interference is.
  • the following describes an example of a processing method after the receiving end side receives the OFDM time domain signal of the M point transmitted by the transmitting end. Specifically: for the embodiment shown in FIG. 2, Any of the following methods can be employed.
  • Method 1 and 1 The receiving end performs frequency transformation on the OFDM time domain signal of the M point to obtain n OFDM time domain symbols of the same point, that is, recovers the time domain diversity characteristic; at this time, in the frequency domain, the data is in the nk.
  • On subcarriers. 2 performing time domain diversity combining on the n OFDM time domain symbols and obtaining an OFDM time domain signal of an M/n point, which can improve the signal to noise ratio (English full name: signal noise ratio, English abbreviation: SNR), the total effect Can improve the performance of anti-pulse interference.
  • 3 Fourier transforming the M/n point of the OFDM time domain signal of the M/n point to obtain an OFDM frequency domain signal; at this time, in the frequency domain, the data is all on the kth subcarrier.
  • the sender and the receiver may pre-negotiate whether the subcarrier carrying the data is the nkth subcarrier. If yes, the receiver may not perform step 1 of the method; if not, the receiver performs the method. All steps.
  • the second method is the same as the step 12 of the method 1.
  • step 3 the OFDM time domain signal of the M/n point is copied n-1 times, and the OFDM time domain signals of the n M/n points are spliced into M.
  • the OFDM time domain signal of the point is then subjected to Fourier transform of the M point OFDM time domain signal to obtain an OFDM frequency domain signal; in this case, in the frequency domain, the data is on the nkth subcarrier.
  • the receiving end may be used to defend the long multipath problem in the following manner. Specifically, the receiving end uses the first i OFDM time domain symbols in the OFDM time domain signal together with the guard interval in the OFDM baseband signal as the target guard interval, and The data is parsed using the target guard interval; wherein 1 ⁇ i ⁇ n-1, i is an integer.
  • the optional implementation is applicable to a scenario in which the multipath length is greater than the length of the CP of the baseband signal.
  • the CP of the OFDM time domain signal and the CP of the baseband signal may be used. Together as the target CP, the multipath length is made smaller than the target CP, so that the receiving end can simplify the calculation process of the frequency domain equalization. For example, suppose the length of the CP of the baseband signal is 264 points, the length of the OFDM time domain signal is 1024 points, and the length of each OFDM time domain symbol is 256 points, as shown in FIG.
  • the time domain diversity gain is lost, but the problem of signal distortion caused by the multipath length exceeding the length of the CP can be avoided, and the performance can be improved as a whole.
  • the sync signal can be positioned to 3*256 points.
  • whether the receiving end performs the optional implementation manner may be controlled by a software switch, or may be determined according to the estimated length of the channel impulse response.
  • FIG. 7 is a schematic structural diagram of an apparatus for generating an OFDM time domain signal according to an embodiment of the present invention.
  • the apparatus 7 shown in FIG. 7 may be the transmitting end in the method shown in FIG. 2 above, and the apparatus 7 is configured to perform the steps in the method shown in FIG. 2.
  • the apparatus 7 includes: a mapping unit 701 and a transform unit 702. .
  • the mapping unit 701 is configured to map data to subcarriers in the target set to generate an OFDM frequency domain signal.
  • the transform unit 702 is configured to perform an inverse Fourier transform of the M point on the OFDM frequency domain signal to generate an OFDM time domain signal of the M point, where the M is a preset sampling point number.
  • the target set includes any one of the following sets: a set formed by the nkth subcarrier, and a set formed by the nk+1th subcarrier. a set of nk+2 subcarriers, ..., a set of nk+n-1 subcarriers.
  • the target set includes any one of the following sets: a set of the nkth subcarriers, and a set of the nk+n/2 subcarriers. .
  • the n is a factor of the M, the n is greater than 1, and the k is taken as [0, (M/n) One or more integers in -1].
  • the apparatus 7 may further include:
  • the receiving unit 703 is configured to receive a narrowband interference detection result.
  • the determining unit 704 is configured to determine the target set according to the narrowband interference detection result.
  • the receiving unit 703 may be a receiver, and the device 7 may further include a transmitter, and the receiver and the transmitter may be integrated to form a transceiver.
  • the mapping unit 701, the transform unit 702, and the determining unit 704 may be embedded in hardware or in a processor independent of the device 7, or may be stored in software in the memory of the device 7, so that the processor calls to execute the above modules. Corresponding operation.
  • FIG. 8 is a schematic structural diagram of an apparatus for generating an OFDM time domain signal according to an embodiment of the present invention.
  • the device 8 shown in FIG. 8 may be the transmitting end in the method shown in FIG. 2 above, and the device 8 is configured to perform the steps in the method shown in FIG. 2.
  • the device 8 includes: a memory 801, a processor 802, System bus 803 and communication interface 804, wherein memory 801, processor 802, and communication interface 804 are coupled together by system bus 803.
  • the memory 801 is configured to store a program.
  • the program can include program code, the program code including computer operating instructions.
  • the processor 802 is configured to execute a program stored in the memory 801 to implement the method for generating an OFDM time domain signal shown in FIG. 2 above.
  • the embodiment further provides a storage medium, which may include a memory 801.
  • FIG. 9 is a schematic structural diagram of an apparatus for generating an OFDM time domain signal according to an embodiment of the present invention.
  • the device 9 shown in FIG. 9 may be the transmitting end in the method shown in FIG. 5 above, and the device 9 is used to execute the steps in the method shown in FIG.
  • the 9 includes: a mapping unit 901, a transform unit 902, and a copy unit 903.
  • the mapping unit 901 is configured to map data onto the subcarriers to obtain an OFDM frequency domain signal.
  • the transform unit 902 is configured to perform an inverse Fourier transform of the M/n point on the OFDM frequency domain signal to obtain an M/n point OFDM time domain signal, where the M is a preset sampling point number, and the n is The factor of M, the n being greater than one.
  • the copying unit 903 is configured to copy the M/n point OFDM time domain signal by n-1 times to obtain an OFDM time domain signal of the M point.
  • the apparatus 9 may further include: an adding unit 904, configured to: the first M/n point OFDM in the OFDM time domain signal of the M point at the sending end Add a guard interval before the time domain signal.
  • mapping unit 901, the transform unit 902, the copy unit 903, and the adding unit 904 may be embedded in hardware or in a processor independent of the device 9, or may be stored in the memory of the device 9 in software. So that the processor calls to perform the operations corresponding to the above modules.
  • FIG. 10 it is a schematic structural diagram of an apparatus for generating an OFDM time domain signal according to an embodiment of the present invention.
  • the device 10 shown in FIG. 10 may be the transmitting end in the method shown in FIG. 5 above, and the device 10 is configured to perform the steps in the method shown in FIG. 5.
  • the device 10 includes: a memory 1001, a processor 1002.
  • the memory 1001 is configured to store a program.
  • the program can include program code, the program code including computer operating instructions.
  • the processor 1002 is configured to execute a program stored in the memory 1001 to implement the method for generating an OFDM time domain signal shown in FIG. 5 above.
  • the embodiment further provides a storage medium, which may include a memory 1001.
  • the memory in this document may include a volatile memory (English: volatile memory), such as random access memory (English name: random-access memory, English abbreviation: RAM); may also include non-volatile memory (English) :non-volatile memory), such as read-only memory (English full name: read-only memory, English abbreviation: ROM), flash memory (English: flash memory), hard disk (English full name: hard disk drive, English abbreviation: HDD) Or a solid state drive (English name: solid-state drive, English abbreviation: SSD); may also include a combination of the above types of memory.
  • a volatile memory such as random access memory (English name: random-access memory, English abbreviation: RAM)
  • non-volatile memory English:non-volatile memory
  • read-only memory English full name: read-only memory, English abbreviation: ROM
  • flash memory English: flash memory
  • hard disk English full name: hard disk drive, English abbreviation: HDD
  • SSD solid state drive
  • the processor can be a central processing unit (English name: central processing unit: English abbreviation: CPU); or other general-purpose processor, digital signal processor (English full name: digital signal processing, English abbreviation: DSP), ASIC (English full name: application specific integrated circuit, English abbreviation: ASIC), field programmable gate array (English full name: field-programmable gate array, English abbreviation: FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete Hardware components, etc.
  • the general purpose processor may be a microprocessor or the processor or any conventional processor or the like. It may also be a dedicated processor, which may include at least one of a baseband processing chip, a radio frequency processing chip, and the like.
  • the system bus can include a data bus, a power bus, a control bus, and a signal status bus.
  • various buses are illustrated as system buses in both FIGS. 9 and 10.
  • the communication interface can be a transceiver.
  • the transceiver can be a wireless transceiver, such as an antenna or the like.
  • the processor transmits and receives data to and from other devices through the communication interface.
  • the disclosed system The apparatus and method can be implemented in other ways.
  • 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, and may be in an electrical, mechanical or other form.
  • 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 purpose of the solution of the embodiment.
  • each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may be physically included 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 hardware plus software functional units.
  • the above-described integrated unit implemented in the form of a software functional unit can be stored in a computer readable storage medium.
  • the software functional units described above are stored in a storage medium and include instructions for causing a computer device (which may be a personal computer, server, or network device, etc.) to perform portions of the steps of the methods described in various embodiments of the present invention.

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Abstract

本发明公开了生成OFDM时域信号的方法和装置，用以有效对抗脉冲干扰。该方法包括：将数据映射到目标集合中的子载波上，生成OFDM频域信号；对OFDM频域信号进行M点的反傅里叶变换，生成M点的OFDM时域信号；若M点的OFDM时域信号是复OFDM时域信号，则目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+1个子载波构成的集合、第nk+2个子载波构成的集合、……、第nk+n-1个子载波构成的集合；若M点的OFDM时域信号是实OFDM时域信号，则目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+n/2个子载波构成的集合；n是M的因子，n大于1，k取[0，(M/n)-1]中的一个或多个整数。

Description

生成OFDM时域信号的方法和装置
本申请要求于2016年03月01日提交中国专利局、申请号为201610116120.7、发明名称为“生成OFDM时域信号的方法和装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及数据处理技术领域，尤其涉及生成正交频分复用(英文全称：Orthogonal Frequency Division Multiplexing，英文缩写：OFDM)时域信号的方法和装置。
背景技术
OFDM技术是一种多载波调制技术。目前，发送端生成OFDM时域信号的方法包括：发送端将数据映射到子载波上，生成OFDM频域信号；然后对OFDM频域信号进行预设采样点数的反傅里叶变换，生成预设采样点数的OFDM时域信号。为了对抗多径干扰，一般需要在OFDM时域信号之前增加保护间隔，其中，保护间隔可以是循环前缀(英文全称：cyclic prefix，英文缩写：CP)。
按照上述方法得到的OFDM时域信号中的OFDM时域符号的周期较长，而OFDM时域符号的周期越长，其在由发送机传输至接收端的过程中，受脉冲干扰影响就越大。
发明内容
本发明的实施例提供一种生成OFDM时域信号的方法和装置，用以有效对抗脉冲干扰。
为达到上述目的，本发明的实施例采用如下技术方案：
第一方面，提供一种生成OFDM时域信号的方法，包括：将数据映射到目标集合中的子载波上，生成OFDM频域信号；并对 所述OFDM频域信号进行M点的反傅里叶变换，生成M点的OFDM时域信号；其中，所述M是预设采样点数。
第二方面，提供一种生成OFDM时域信号的装置，包括：映射单元和变换单元；其中，映射单元，用于将数据映射到目标集合中的子载波上，生成OFDM频域信号；变换单元，用于对所述OFDM频域信号进行M点的反傅里叶变换，生成M点的OFDM时域信号；其中，所述M是预设采样点数。
其中，在上述第一方面或第二方面中，若所述M点的OFDM时域信号是复OFDM时域信号，则所述目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+1个子载波构成的集合、第nk+2个子载波构成的集合、……、第nk+n-1个子载波构成的集合；若所述M点的OFDM时域信号是实OFDM时域信号，则所述目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+n/2个子载波构成的集合；所述n是所述M的因子，所述n大于1，所述k取[0，(M/n)-1]中的一个或多个整数。
在上述第一方面或第二方面提供的技术方案中，若数据被映射在第nk个子载波构成的集合中的子载波上，则所得到的OFDM时域信号中包括n个相同的OFDM时域符号；若数据被映射在下述任一集合中的子载波上：第nk+1个子载波构成的集合、第nk+2个子载波构成的集合、……、第nk+n-1个子载波构成的集合，则可以通过对所生成的OFDM时域信号进行频率变换，从而使得频率变换后的OFDM时域信号中包括n个相同的OFDM时域符号。n大于1。因此，与现有技术相比，能够缩短OFDM时域符号的周期，因此能够有效对抗脉冲干扰。
在本发明实施例中，一个M点的OFDM时域信号对应一个目标集合；不同的OFDM时域信号可以对应同一个目标集合，也可以对应不同的目标集合。下面提供一种确定目标集合的方法，当然 具体实现时不限于此。
结合上述第一方面，可选的，在所述发送端将数据映射到目标集合中的子载波上，生成OFDM频域信号之前，该方法还可以包括：接收窄带干扰检测结果；并根据所述窄带干扰检测结果，确定所述目标集合。
对应地，第二方面提供的装置还可以包括：接收单元和确定单元；接收单元用于接收窄带干扰检测结果；确定单元，用于根据所述窄带干扰检测结果，确定所述目标集合。该可选的实现方式能够有效地避免窄带干扰。
可选的，结合上述第一方面，该方法还可以包括：为OFDM时域信号添加保护间隔，具体的：在M点的OFDM时域信号之前添加保护间隔。对应地，上述第二方面中的装置还可以包括添加单元，用于为M点的OFDM时域信号添加保护间隔。
第三方面，提供一种生成OFDM时域信号的方法，包括：数据映射到子载波上，得到OFDM频域信号；并对所述OFDM频域信号进行M/n点的反傅里叶变换，得到M/n点OFDM时域信号；其中，所述M是预设采样点数，所述n是所述M的因子，所述n大于1；然后，将所述M/n点OFDM时域信号拷贝n-1次，得到M点的OFDM时域信号。
第四方面，提供一种生成OFDM时域信号的装置，包括：映射单元、变换单元和拷贝单元；其中，映射单元，用于将数据映射到子载波上，得到OFDM频域信号；变换单元，用于对所述OFDM频域信号进行M/n点的反傅里叶变换，得到M/n点OFDM时域信号；其中，所述M是预设采样点数，所述n是所述M的因子，所述n大于1；拷贝单元，用于将所述M/n点OFDM时域信号拷贝n-1次，得到M点的OFDM时域信号。
上述第三方面或第四方面提供的技术方案中，将n个相同的 M/n点的OFDM时域信号拼接为一个M点的OFDM时域信号，这样，可以将M/n点的OFDM时域信号看作M点的OFDM时域信号中的一个OFDM时域符号；由此可知，在预设采样率M不变的情况下，与现有技术相比，本发明实施例缩短了OFDM时域符号的周期，因此能够有效对抗脉冲干扰。
在上述第三方面中，可选的，在所述发送端将所述M/n点OFDM时域信号拷贝n-1次，得到M点的OFDM时域信号之后，该方法还可以包括：在所述M点的OFDM时域信号中的首个所述M/n点OFDM时域信号之前，添加保护间隔。对应地，在上述第四方面中，该装置还可以包括：添加单元，用于：在所述M点的OFDM时域信号中的首个所述M/n点OFDM时域信号之前，添加保护间隔。其中，本发明实施例对保护间隔的具体填充内容不进行限定，例如可以利用现有技术中的任一种方式实现。
第五方面，本发明实施例提供了一种生成OFDM时域信号的装置，该装置具有实现上述第一方面提供的方法的功能。所述功能可以通过硬件实现，也可以通过硬件执行相应的软件实现。所述硬件或软件包括一个或多个与上述功能相对应的模块。在一种可能的实现方式中，该装置的结构中包括处理器和收发器，处理器被配置为支持该装置执行上述第一方面的方法中相应的功能。收发器用于支持该装置与其他设备之间进行通信。该装置还可以包括存储器，所述存储器用于与处理器耦合，其保存该装置中必要的程序指令和数据。
第六方面，本发明实施例提供了一种存储介质，用于储存为上述第一方面的方法中所用的计算机软件指令，其包含用于执行上述第一方面中的所有动作对应的程序。
第七方面，本发明实施例提供了一种生成OFDM时域信号的装置，该装置具有实现上述第二方面提供的方法的功能。所述功能 可以通过硬件实现，也可以通过硬件执行相应的软件实现。所述硬件或软件包括一个或多个与上述功能相对应的模块。在一种可能的实现方式中，该装置的结构中包括处理器和收发器，处理器被配置为支持该装置执行上述第二方面的方法中相应的功能。收发器用于支持该装置与其他设备之间进行通信。该装置还可以包括存储器，所述存储器用于与处理器耦合，其保存该装置中必要的程序指令和数据。
第八方面，本发明实施例提供了一种存储介质，用于储存为上述第二方面的方法中所用的计算机软件指令，其包含用于执行上述第二方面中的所有动作对应的程序。
附图说明
图1为本发明实施例提供的一种OFDM基带信号的格式示意图；
图2为本发明实施例提供的一种生成OFDM时域信号的方法的流程图；
图3为现有技术中提供的一种OFDM时域信号的格式示意图；
图4为现有技术与本发明实施例中的OFDM基带信号的对比示意图；
图5为本发明实施例提供的另一种生成OFDM时域信号的方法的流程图；
图6为本发明实施例提供的一种OFDM基带信号的格式示意图；
图7为本发明实施例提供的一种生成OFDM时域信号的装置的结构示意图；
图8为本发明实施例提供的另一种生成OFDM时域信号的装置的结构示意图；
图9为本发明实施例提供的另一种生成OFDM时域信号的装置 的结构示意图；
图10为本发明实施例提供的另一种生成OFDM时域信号的装置的结构示意图。
具体实施方式
如图1所示，是OFDM基带信号的格式示意图。其中，OFDM基带信号由OFDM时域信号和该OFDM时域信号对应的CP构成。OFDM时域信号的长度与预设采样点数和采样频率有关；当采样频率一定时，预设采样点数越大，OFDM时域信号的长度就越长，预设采样点数是根据信道环境来确定的；CP的长度由信道的最大多径时延决定。
按照上述方法得到的预设采样点数的OFDM时域信号中仅包含一个OFDM时域符号，因此，这样得到的OFDM时域符号的周期较长，这会导致OFDM时域符号受脉冲干扰较大。
基于此，本发明实施例提供了一种生成OFDM时域信号的方法和装置，用以有效对抗脉冲干扰。
本文中的长度是指时域长度，即持续时间；例如，OFDM时域符号的长度是指OFDM时域符号的持续时间，CP的长度是指CP的持续时间。由于长度与采样频率和采样点数有关，在本发明实施例中认为采样频域始终不变，因此，可以利用采样点数表示长度，例如，假设OFDM时域信号的长度是1024点，CP的长度是264点，多径长度是200点。
本文中提供的生成OFDM时域信号的方法的执行主体可以是发送端，本文中的发送端和接收端均可以包括但不限于：基站、用户设备(英文全称：user equipment，英文缩写：UE)、接入点(英文全称：access point，英文缩写：AP)等。本文中的“多个”是指两个或两个以上。
下面结合附图，对本发明实施例中的技术方案进行描述。以下 实施例中均以发送端如何生成M点的OFDM时域信号进行说明。
如图2所示，为本发明实施例提供的一种生成OFDM时域信号的方法的流程图，图2所示的方法包括以下步骤S101-S102：
S101：发送端将数据映射到目标集合中的子载波上，生成OFDM频域信号。
S102：发送端对OFDM频域信号进行M点的反傅里叶变换，生成M点的OFDM时域信号；M是预设采样点数。
其中，若OFDM时域信号是复OFDM时域信号，则目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+1个子载波构成的集合、第nk+2个子载波构成的集合、……、第nk+n-1个子载波构成的集合。若OFDM时域信号是实OFDM时域信号，则目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+n/2个子载波构成的集合。n是M的因子，n大于1；k取[0，(M/n)-1]中的一个或多个整数。
示例的，如果OFDM时域信号是复OFDM时域信号，那么：若n＝4，则数据可以均被映射到第4k个子载波上，或者被映射到第4k+1个子载波上，或者被映射到第4k+2个子载波上，或者被映射到第4k+3个子载波上。若n＝2，则数据可以被映射到第2k个子载波上，或者被映射到第2k+1个子载波上。如果OFDM时域信号是实OFDM时域信号，那么：若n＝4，则数据可以被映射到第4k个子载波上，或者被映射到第4k+2个子载波上。若n＝2，则数据可以被映射到第2k个子载波上，或者被映射到第2k+1个子载波上。
其中，“数据”是指发送端需要发送给接收端的数据。反傅里叶变换可以是快速傅里叶逆变换(英文全称：inverse fast fourier transform，英文缩写：IFFT)，下文中均以此为例进行说明。需要说明的是，为了简洁，在本实施例中，下述OFDM时域信号均是指M点的OFDM时域信号。
当OFDM时域信号是实OFDM时域信号时，OFDM频域信号需要满足复共轭对称性，其中，复共轭对称性要求：第0个子载波和第M/2个子载波上是实数，并且，第t个子载波与第M-t个子载波复共轭对称，t可以取到[1，M-1]中的所有整数。例如，M＝1024，子载波的编号为0、1、2、……、1023，则复共轭对称性要求：第0个子载波和第512个子载波上被映射的数据是实数，且第1个子载波与第1023个子载波复共轭对称，第2个子载波与第1022个子载波复共轭对称、……、第510个子载波与第514个子载波复共轭对称。
具体实现时，为了满足某些国家或地区的规定，或者其他要求，使得某些子载波不能使用，k的取值可以是不连续的，也就是说，在本发明实施例中，k的取值的灵活性较强，可以根据实际需要进行设定。
一个OFDM时域信号对应一个目标集合；不同的OFDM时域信号可以对应一个目标集合或对应不同的目标集合。例如，若M＝1024，n＝4，且OFDM时域信号是复OFDM时域信号，则第1个1024点的OFDM时域信号可以对应第4k个子载波构成的集合，第2个1024点的OFDM时域信号可以对应第4k+1个子载波构成的集合，第3个1024点的OFDM时域信号可以对应第4k个子载波构成的集合。当然，还可以有其他实现方式，在此不再一一列举。
若数据被映射在第nk个子载波构成的集合上，则S102中所生成的OFDM时域信号由n个相同的OFDM时域符号构成，每个OFDM时域符号的长度是M/n点。而现有技术中的OFDM时域信号是由一个M点的OFDM时域符号构成。如图4所示，是现有技术与本发明实施例中的OFDM基带信号的对比示意图。图4中是以CP的长度是256点，OFDM时域信号的长度是1024点为例进行说明的，这样，现有技术中的一个OFDM时域符号的周期是1024点，如图4中的(a) 所示，本发明实施例中的一个OFDM时域符号的周期是256点，如图4(b)中所示。
若数据被映射在了以下任一集合中的子载波上：第nk+1个子载波构成的集合、第nk+2个子载波构成的集合、……、第nk+n-1个子载波构成的集合，则可以通过接收端对M点的OFDM时域信号进行频率变换，使得变换后数据都在第nk个子载波上，这样，变换后的OFDM时域信号由n个相同的OFDM时域符号构成，每个OFDM时域符号的长度是M/n点。需要说明的是，接收端执行频率变换所针对的OFDM时域信号是经电力线信道传输后得到的时域信号。
由上述描述可知，与现有技术相比，缩短了OFDM时域符号的周期，因此能够有效对抗脉冲干扰。
另外，在本发明实施例中，由于在OFDM频域信号中，相邻的映射有数据的两个子载波之间间隔一定数量个子载波，因此，在保证时域平均功率不变的情况下，发送端可以将未映射有数据的子载波的发送功率挪用到映射有数据的子载波上，从而使得每个映射有数据的子载波的发送功率提升n倍，从而可以提升接收端对信号的接收性能。其中，子载波的发送功率是指发送端发送一个子载波上的数据时所使用的功率。
需要说明的是，现有技术中，为了对抗脉冲干扰，OFDM时域符号的周期应该尽量短一些，一种实现方式是：在多径长度不变，即CP的长度不变的情况下，缩短OFDM时域符号的周期；这样，会导致数据的传输效率大大降低。例如，假设采样率是25MHz(兆赫兹)，预设采样点是1024；CP的长度是OFDM时域符号的周期的1/4，那么，可以使用1024点表示OFDM时域符号的周期，用256点表示CP的长度，如图3中的(a)所示，该情况下，数据的传输效率是：1024/(256+1024)＝80％。为了对抗脉冲干扰，将OFDM时域符号的周期缩短为256点，如图3中的(b)所示，该情况下， 数据的传输效率是：256/(256+256)＝50％。显然，在缩短OFDM时域的周期后，数据的传输效率大大降低。
另外，现有技术中，为了对抗信道中的衰减和噪声，发送端一般需要对数据进行多次拷贝(例如4次、5次或8次等)，但是，这些拷贝均发生在频域上，即是对数据进行频域分集处理。
由于现有技术中本身需要对数据进行多次拷贝，为了更好地与现有技术进行对比，可以将本发明实施例提供的技术方案理解为：将部分或全部次数的频域上的拷贝，移到了时域上，在拷贝总次数相同的情况下，其能够达到与现有技术中同等的对抗信道中的衰减和噪声的效果。示例的，假设发送端需要对数据进行8次拷贝，则可以按照本发明实施例提供的技术方案在时域上对数据进行4次拷贝(具体的，在S101中，n＝4)，然后按照现有技术中的方法在频域上对数据进行2次拷贝。由于在拷贝的总次数相等的情况下，数据的传输效率相等。因此，在数据的拷贝的总次数相等的情况下，与图3所示的现有技术相比，本发明实施例的技术方案能够在对抗脉冲干扰的同时，保证数据的传输效率不变。
其中，严格地讲，本发明实施提供的将数据映射在第nk个子载波上的技术方案，可以理解为将部分或全部次数的频域上的拷贝，移到了时域上；而将数据映射在其他目标集合上的技术方案，在配合频率变换操作后，可以相当于是将部分或全部次数的频域上的拷贝，移到了时域上。
可选的，提供一种发送端选择目标集合的方法：发送端接收窄带干扰检测结果(具体的：发送端接收将接收端发送的窄带干扰检测结果)；然后，根据该窄带干扰检测结果，确定目标集合。具体实现时，不限于此。
其中，窄带干扰检测结果可以用于指示以下信息中的至少一种：发送端与接收端的传输频带上哪些窄带上的干扰较大，哪些窄带上 的干扰较小，任意的一个或多个窄带上的干扰值等。本发明实施例对接收端获取测量窄带干扰检测结果的具体实现方式不进行限定，例如可以利用现有技术中的方法实现。发送端可以根据窄带干扰检测结果，将干扰较小的子载波集合确定为目标集合。
具体实现时，在S101之前，该方法还可以包括：发送端确定M和n的取值。其中，M可以根据信道环境来确定，n可以根据数据拷贝的总次数和在频域上的拷贝次数等确定。n的取值越大，对抗脉冲干扰的效果就越好，并且可以更有效地避开窄带干扰。
可选的，在S102之后，该方法还可以包括：发送端为M点的OFDM时域信号添加保护间隔，得到OFDM基带信号。具体的：若保护间隔是CP，则发送端可以根据信道的最大多径时延确定CP的长度，然后取该M点的OFDM时域信号的尾部的与该CP的长度相等的一段数据作为CP的内容，最后，在M点的OFDM时域信号之前添加该CP。一种示例如图4中的(b)所示。具体实现时，保护间隔不限于是CP。
如图5所示，是本发明实施例提供的另一种生成OFDM时域信号的方法的流程图。图5所示的方法包括：
S201：发送端将数据映射到子载波上，得到OFDM频域信号。
S202：发送端对该OFDM频域信号进行M/n点的反傅里叶变换，得到M/n点OFDM时域信号；其中，M是预设采样点数，n是M的因子，n大于1。
S203：发送端将M/n点OFDM时域信号拷贝n-1次，得到M点的OFDM时域信号。
在S203之后，该方法还可以包括：发送端为M点的OFDM时域信号添加保护间隔。具体的：若保护间隔是CP，则发送端可以根据信道的最大多径时延确定CP，取该M点的OFDM时域信号的尾部的与该CP的长度相等的一段数据作为CP的内容，最后，在该M 点的OFDM时域信号的首个M/n点的OFDM时域符号之前添加该CP。一种示例如图4中的(b)所示。
本实施例提供的技术方案可以理解为将n个相同的M/n点的OFDM时域信号拼接为一个M点的OFDM时域信号，这样，可以将M/n点的OFDM时域信号看作M点的OFDM时域信号中的一个OFDM时域符号；由此可知，在预设采样率M不变的情况下，与现有技术相比，本发明实施例缩短了OFDM时域符号的周期，因此能够有效对抗脉冲干扰。
另外，如上文所示，在数据拷贝总次数相等的情况下，与现有技术相比，该实施例能够在有效对抗脉冲干扰的同时，保证数据的传输效率不变。
图5所示的实施例与图2所示的实施例的区别在于：
第一，图5所示的实施例中的M点的OFDM时域信号中包含n个相同的OFDM时域符号，是严格意义上的时域分集；图2所示的实施例中只有当数据映射在第nk个子载波上时，所生成的M点的OFDM时域信号才是严格意义上的时域分集，当数据映射到其他集合上时，所生成的OFDM时域信号需要经频率变换后，才能实现严格意义上的时域分集。
第二，图5所示的实施例中的数据被映射在了第k个子载波上，即是按照现有技术中的方法进行映射的；图2所示的实施例中的数据被映射在了上文所提供的任一目标集合上。
图2所示的实施例中，发送端也可以根据信道环境确定M，根据数据拷贝的总次数和在频域上的拷贝次数等确定n。n的取值越大，OFDM时域信号中的OFDM时域符号的周期就越短，对抗脉冲干扰的效果就越好。
下面举例说明接收端侧在接收到发送端发送的上述M点的OFDM时域信号之后的处理方法。具体的：对于图2所示的实施例， 可以采用以下方法中的任一种。
方法一、①接收端对M点的OFDM时域信号进行频率变换，以得到n个相同点数的OFDM时域符号，即恢复时域分集特性；此时，在频域上，数据均在第nk个子载波上。②对该n个OFDM时域符号进行时域分集合并，得到一个M/n点的OFDM时域信号，这样可以提升信噪比(英文全称：signal noise ratio，英文缩写：SNR)，总的效果可以提升抗脉冲干扰的性能。③对该M/n点的OFDM时域信号进行M/n点的傅里叶变换，得到OFDM频域信号；此时，频域上，数据均在第k个子载波上。
需要说明的是，发送端和接收端可以预先协商好承载数据的子载波是否是第nk个子载波，若是，则接收端可以不执行该方法的步骤①；若否，则接收端执行该方法的全部步骤。
方法二、与方法一的步骤①②相同，区别在于：步骤③中，对M/n点的OFDM时域信号拷贝n-1次，并将n个M/n点的OFDM时域信号拼接为M点的OFDM时域信号；然后对M点的OFDM时域信号进行M点的傅里叶变换，得到OFDM频域信号；该情况下，频域上，数据均在第nk个子载波上。
可选的，接收端可以按照以下方式对抗长多径问题，具体的：接收端将OFDM时域信号中的前i个OFDM时域符号与OFDM基带信号中的保护间隔一起作为目标保护间隔，并利用所述目标保护间隔，解析出数据；其中，1≤i≤n-1，i是整数。
该可选的实现方式适用于多径长度大于基带信号的CP的长度的场景中，在该场景中，可以通过将OFDM时域信号中的前一个或多个OFDM时域符号与基带信号的CP一起作为目标CP，从而使得多径长度小于目标CP，这样，接收端可以简化频域均衡的计算过程。例如，假设基带信号的CP的长度是264点，OFDM时域信号的长度是1024点，每个OFDM时域符号的长度是256点，如图6所示，那 么，若多径长度是400点，则多径长度大于CP的长度；该情况下，可以将第1个OFDM时域符号与基带信号的CP一起作为目标CP，则目标CP的长度是256+264＝520点，从而使得目标CP大于多径长度。这样，损失了时域分集增益，但是能够避免因多径长度超过CP的长度而导致的信号失真的问题，总体上能够提升性能。
在该可选的实现方式中，接收端在进行信号同步时，可以将同步信号定位到[(n-1)*M]/n点，例如，若M＝1024，n＝4，则接收端可以将同步信号定位到3*256点。另外，接收端是否执行该可选的实现方式可以通过软件开关进行控制，或者根据估计的信道冲击响应的长度来进行判断等。
如图7所示，是本发明实施例提供的一种生成OFDM时域信号的装置的结构示意图。图7所示的装置7可以是上文图2所示的方法中的发送端，该装置7用以执行图2所示的方法中的各步骤，装置7包括：映射单元701和变换单元702。
映射单元701，用于将数据映射到目标集合中的子载波上，生成OFDM频域信号。
变换单元702，用于对所述OFDM频域信号进行M点的反傅里叶变换，生成M点的OFDM时域信号；其中，所述M是预设采样点数。
其中，若所述M点的OFDM时域信号是复OFDM时域信号，则所述目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+1个子载波构成的集合、第nk+2个子载波构成的集合、……、第nk+n-1个子载波构成的集合。
若所述M点的OFDM时域信号是实OFDM时域信号，则所述目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+n/2个子载波构成的集合。
所述n是所述M的因子，所述n大于1，所述k取[0，(M/n) -1]中的一个或多个整数。
可选的，如图7所示，所述装置7还可以包括：
接收单元703，用于接收窄带干扰检测结果；
确定单元704，用于根据所述窄带干扰检测结果，确定所述目标集合。
在硬件实现上，上述接收单元703可以为接收器，另外装置7还可以包括发送器，该接收器和该发送器可以集成在一起构成收发器。映射单元701、变换单元702和确定单元704可以以硬件形式内嵌于或独立于装置7的处理器中，也可以以软件形式存储于装置7的存储器中，以便于处理器调用执行以上各个模块对应的操作。
如图8所示，是本发明实施例提供的一种生成OFDM时域信号的装置的结构示意图。图8所示的装置8可以是上文图2所示的方法中的发送端，该装置8用以执行图2所示的方法中的各步骤，装置8包括：存储器801、处理器802、***总线803和通信接口804，其中，存储器801、处理器802和通信接口804通过***总线803耦合在一起。存储器801，用于存放程序。具体地，程序可以包括程序代码，所述程序代码包括计算机操作指令。处理器802，用于执行所述存储器801存放的程序，以实现上文中的图2所示的生成OFDM时域信号的方法。
本实施例还提供一种存储介质，该存储介质可以包括存储器801。
本实施例中相关内容的解释可以参考上文，并且，本实施例提供的装置7、8能够达到的有益效果可以参考上文提供的图2所示的方法能够达到的有益效果，此处不再赘述。
如图9所示，是本发明实施例提供的一种生成OFDM时域信号的装置的结构示意图。图9所示的装置9可以是上文图5所示的方法中的发送端，该装置9用以执行图5所示的方法中的各步骤，装 置9包括：映射单元901、变换单元902和拷贝单元903。
映射单元901，用于将数据映射到子载波上，得到OFDM频域信号。
变换单元902，用于对所述OFDM频域信号进行M/n点的反傅里叶变换，得到M/n点OFDM时域信号；其中，所述M是预设采样点数，所述n是所述M的因子，所述n大于1。
拷贝单元903，用于将所述M/n点OFDM时域信号拷贝n-1次，得到M点的OFDM时域信号。
可选的，如图9所示，所述装置9还可以包括：添加单元904，用于：所述发送端在所述M点的OFDM时域信号中的首个所述M/n点OFDM时域信号之前，添加保护间隔。
在硬件实现上，映射单元901、变换单元902、拷贝单元903和添加单元904可以以硬件形式内嵌于或独立于装置9的处理器中，也可以以软件形式存储于装置9的存储器中，以便于处理器调用执行以上各个模块对应的操作。
如图10所示，是本发明实施例提供的一种生成OFDM时域信号的装置的结构示意图。图10所示的装置10可以是上文图5所示的方法中的发送端，该装置10用以执行图5所示的方法中的各步骤，装置10包括：存储器1001、处理器1002、***总线1003和通信接口1004，其中，存储器1001、处理器1002和通信接口1004通过***总线1003耦合在一起。存储器1001，用于存放程序。具体地，程序可以包括程序代码，所述程序代码包括计算机操作指令。处理器1002，用于执行所述存储器1001存放的程序，以实现上文中的图5所示的生成OFDM时域信号的方法。
本实施例中相关内容的解释可以参考上文，并且，本实施例提供的装置9、10能够达到的有益效果可以参考上文提供的图5所示的方法能够达到的有益效果，此处不再赘述。
本实施例还提供一种存储介质，该存储介质可以包括存储器1001。
示例的，本文中的存储器可以包括易失性存储器(英文：volatile memory)，例如随机存取存储器(英文全称：random-access memory，英文缩写：RAM)；也可以包括非易失性存储器(英文：non-volatile memory)，例如只读存储器(英文全称：read-only memory，英文缩写：ROM)，快闪存储器(英文：flash memory)，硬盘(英文全称：hard disk drive，英文缩写：HDD)或固态硬盘(英文全称：solid-state drive，英文缩写：SSD)；还可以包括上述种类的存储器的组合。
处理器可以为中央处理器(英文全称：central processing unit，英文缩写：CPU)；也可以为其他通用处理器、数字信号处理器(英文全称：digital signal processing，英文缩写：DSP)、专用集成电路(英文全称：application specific integrated circuit，英文缩写：ASIC)、现场可编程门阵列(英文全称：field-programmable gate array，英文缩写：FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。还可以为专用处理器，该专用处理器可以包括基带处理芯片、射频处理芯片等中的至少一个。
***总线可以包括数据总线、电源总线、控制总线和信号状态总线等。本实施例中为了清楚说明，在图9和图10中均将各种总线都示意为***总线。
通信接口可以是收发器。该收发器可以为无线收发器，例如可以是天线等。处理器通过通信接口与其他设备之间进行数据的收发。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，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。另一点，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，可以是电性，机械或其它的形式。
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包括，也可以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，也可以采用硬件加软件功能单元的形式实现。
上述以软件功能单元的形式实现的集成的单元，可以存储在一个计算机可读取存储介质中。上述软件功能单元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部分步骤。
最后应说明的是：以上实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施例技术方案的精神和范围。

Claims (8)

  1. 一种生成正交频分复用OFDM时域信号的方法，其特征在于，包括：
    将数据映射到目标集合中的子载波上，生成OFDM频域信号；
    对所述OFDM频域信号进行M点的反傅里叶变换，生成M点的OFDM时域信号；其中，所述M是预设采样点数；
    其中，若所述M点的OFDM时域信号是复OFDM时域信号，则所述目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+1个子载波构成的集合、第nk+2个子载波构成的集合、……、第nk+n-1个子载波构成的集合；
    若所述M点的OFDM时域信号是实OFDM时域信号，则所述目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+n/2个子载波构成的集合；
    所述n是所述M的因子，所述n大于1，所述k取[0，(M/n)-1]中的一个或多个整数。
  2. 根据权利要求1所述的方法，其特征在于，在所述将数据映射到目标集合中的子载波上，生成OFDM频域信号之前，所述方法还包括：
    接收窄带干扰检测结果；
    根据所述窄带干扰检测结果，确定所述目标集合。
  3. 一种生成正交频分复用OFDM时域信号的方法，其特征在于，包括：
    将数据映射到子载波上，得到OFDM频域信号；
    对所述OFDM频域信号进行M/n点的反傅里叶变换，得到M/n点OFDM时域信号；其中，所述M是预设采样点数，所述n是所述M的因子，所述n大于1；
    将所述M/n点OFDM时域信号拷贝n-1次，得到M点的OFDM 时域信号。
  4. 根据权利要求3所述的方法，其特征在于，在所述将所述M/n点OFDM时域信号拷贝n-1次，得到M点的OFDM时域信号之后，所述方法还包括：
    在所述M点的OFDM时域信号中的首个所述M/n点OFDM时域信号之前，添加保护间隔。
  5. 一种生成正交频分复用OFDM时域信号的装置，其特征在于，包括：
    映射单元，用于将数据映射到目标集合中的子载波上，生成OFDM频域信号；
    变换单元，用于对所述OFDM频域信号进行M点的反傅里叶变换，生成M点的OFDM时域信号；其中，所述M是预设采样点数；
    其中，若所述M点的OFDM时域信号是复OFDM时域信号，则所述目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+1个子载波构成的集合、第nk+2个子载波构成的集合、……、第nk+n-1个子载波构成的集合；
    若所述M点的OFDM时域信号是实OFDM时域信号，则所述目标集合包括以下集合中的任一种：第nk个子载波构成的集合、第nk+n/2个子载波构成的集合；
    所述n是所述M的因子，所述n大于1，所述k取[0，(M/n)-1]中的一个或多个整数。
  6. 根据权利要求5所述的装置，其特征在于，所述装置还包括：
    接收单元，用于接收窄带干扰检测结果；
    确定单元，用于根据所述窄带干扰检测结果，确定所述目标集合。
  7. 一种生成正交频分复用OFDM时域信号的装置，其特征在于，包括：
    映射单元，用于将数据映射到子载波上，得到OFDM频域信号；
    变换单元，用于对所述OFDM频域信号进行M/n点的反傅里叶变换，得到M/n点OFDM时域信号；其中，所述M是预设采样点数，所述n是所述M的因子，所述n大于1；
    拷贝单元，用于将所述M/n点OFDM时域信号拷贝n-1次，得到M点的OFDM时域信号。
  8. 根据权利要求7所述的装置，其特征在于，所述装置还包括：
    添加单元，用于：所述发送端在所述M点的OFDM时域信号中的首个所述M/n点OFDM时域信号之前，添加保护间隔。
PCT/CN2016/107530 2016-03-01 2016-11-28 生成ofdm时域信号的方法和装置 WO2017148189A1 (zh)

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CN105656832B (zh) * 2016-03-01 2019-10-22 华为技术有限公司 生成ofdm时域信号的方法和装置
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