CN101166362B

CN101166362B - Method and equipment for originating and detecting reverse access

Info

Publication number: CN101166362B
Application number: CN2006101626499A
Authority: CN
Inventors: 阮卫; 杜颖钢; 李斌; 罗毅
Original assignee: Huawei Technologies Co Ltd
Current assignee: State Grid Corp of China SGCC; Xinxiang Power Supply Co of State Grid Henan Electric Power Co Ltd
Priority date: 2006-10-20
Filing date: 2006-11-28
Publication date: 2011-03-16
Anticipated expiration: 2026-11-28
Also published as: WO2008049321A1; CN101166362A

Abstract

The invention improves capability for wireless terminal moved in high speed to reverse access channel. The method groups signature sequences. Different groups of signature sequences are utilized in different speed ranges. Using blocked mode, network side receives signed signature sequence groups in high speed so as to raise performance of reverse access channel. Different blocked modes are utilized to detect groups of signature sequences in different speed ranges. The blocked mode is not utilized for the signature sequence group in lowest speed; and the signature sequence group in higher speed utilizes smaller block. Using only one signature sequence group under one blocked mode carries out correlation detection. Partitioned blocks can be superposed each other. Shorter signature sequence can be selected for wireless terminal closer to base station; and longer signature sequence can be selected for wireless terminal farther to base station.

Description

Method and device for initiating and detecting reverse access

Technical Field

The present invention relates to the field of wireless communications, and more particularly, to a reverse access technique in a wireless communication system.

Background

A cellular mobile communication system generally divides a service area into a plurality of cells, each of which is provided with radio coverage by a corresponding base station and provides service, thereby providing service over a large area, and has been most widely used in the existing wireless mobile communication systems. In a cellular mobile communication system, terminals are connected via radio links to base stations, each of which needs to communicate with a certain number of terminals simultaneously.

Terminals are randomly dispersed throughout the coverage of each base station in the communication system. When the terminal needs to communicate with the base station, a reverse access process needs to be initiated. The access control technology is a control method for realizing the access of a terminal to a wireless channel in a mobile communication system. As the number of terminals increases dramatically, higher demands are being made on access control techniques in mobile communication systems.

A brief description of an access control technique in a mobile communication system is provided below. In a mobile communication system, when a terminal moves in each neighboring cell, after entering a cell and completing location registration, the terminal resides in the cell and enters an idle state, which is also called a current cell of the terminal. In idle state, if the terminal performs a cell location update procedure, or needs to respond to a page from a cell, or needs to establish a call with another terminal, including a service request, a short message request, etc., the terminal will send a reverse access request to the current cell base station. It should be noted that the reverse access procedure is initiated by the terminal. The terminal sends an access request to the cell base station on a reverse access channel to perform access probing. When the network side receives the access request of the terminal, the network side returns a channel allocation message to the terminal on a common channel, and then the terminal and the base station perform data interaction on the allocated specific channel. It should be further noted that the reverse access procedure initiated by the terminal is completed according to the access resource of the base station of the current cell and according to a specific algorithm. The terminal selects the access time slot in the available access resources, the selection is random, and then after the base station receives the access probe of the mobile station, the cell base station sends an access indication message to the terminal to indicate whether the current terminal is successfully accessed. If the reverse access is unsuccessful, the terminal backs off for a period of time and re-initiates the reverse access request.

Wherein, the reverse access channel is generally composed of two parts of prefix and message. The prefix function is to realize uplink synchronization, carry random ID, and other information. The message part typically carries connection request information etc. Since the message part is not the inventive point of the present invention, it will not be described in detail here.

The reverse access prefix is also known as a reverse access probe. The design of the reverse access prefix needs to consider the difficulty of the base station in acquiring the prefix sequence. In addition to the signature sequence type used by the prefix, the length of the time domain occupied by the reverse access prefix also has a certain influence on the difficulty of acquisition of the base station. This is because the maximum power transmitted by the terminal per unit time is limited, and a large detection energy can be obtained only by accumulation over time. Therefore, for a low-speed terminal, prefixes occupying more time slices can obtain larger detection energy, so that the base station can capture prefix sequences, and the terminal can be successfully accessed; the detection energy obtained by the prefixes occupying fewer time slices is smaller, and the base station is difficult to capture the prefix sequence under the condition of poor channel quality. Therefore, in order to improve the access probability of the terminal, a prefix with a longer duration may be used. However, for a high-speed terminal, since the channel changes rapidly over time and the reverse access employs non-coherent detection, so that the detection performance of the prefix with a longer duration is poor and the access probability is difficult to guarantee, so improving the access performance of the high-speed terminal is the focus of current attention.

The design of the reverse access prefix used in one current protocol is shown in fig. 1:

the transmitting end firstly selects a signature sequence from candidate signature sequences, and in the scheme, 1024-bit Walsh codes are used as the signature sequences. After being scrambled by a scrambling code, the 1024-bit signature sequence is arranged into a matrix of 128 rows and 8 columns. Each column is passed through a 128-point Discrete fourier transform ("DFT"). The 128 data obtained after the transformation are mapped to 128 continuous subcarriers of an Orthogonal Frequency Division Multiplexing (OFDM) system, and are modulated by OFDM, including Inverse Fast Fourier Transform (IFFT) at 512 points, added with a cyclic prefix, and then transmitted through an antenna. A total of 8 columns, occupying 8 OFDM symbols, are transmitted. In 802.20, one physical frame contains 8 OFDM symbols, so the transmission of the reverse access prefix occupies 128 subcarriers on one physical frame.

At the receiving end, as shown in fig. 2, firstly, OFDM demodulation is performed on signals received by antennas, including de-cyclic embedding and Fast Fourier Transform (FFT) at 512 points, and then prefix data is extracted from 128 corresponding subcarriers at the time of transmission, so as to form a column, and 8 columns are extracted in total. Each line of data is subjected to 128-point Inverse Discrete Fourier Transform (IDFT) to obtain 128 demodulated signature sequence data. The demodulated signature sequence data of 8 columns of 128 elements is rearranged and restored to a scrambled 1024 element sequence, and the sequence is descrambled and subjected to correlation detection of 1024-bit Walsh codes to obtain a detection signal. And judging whether to capture the prefix according to whether the detection signal exceeds the threshold, if so, considering to capture the prefix, and the base station sends confirmation information to the terminal in a downlink channel, and if not, considering not to capture the prefix.

In practical applications, there are the following problems: the access probability of a terminal moving at a high speed cannot be ensured by adopting the existing method to send the reverse access prefix.

The main reason for this is that for a terminal moving at a high speed, for example, a terminal moving at a speed of 350km/h, since the channel variation is too fast, the performance of the non-correlation detection is greatly reduced, the difficulty of the base station in acquiring the reverse access request is increased, the existing method is adopted to transmit the reverse access prefix, even if the channel quality is good, the base station is difficult to acquire the reverse access prefix, and the probability of the terminal reverse access is greatly reduced.

Disclosure of Invention

The main technical problem to be solved by the embodiments of the present invention is to provide a method and a device for initiating and detecting reverse access, so that the performance of a wireless terminal moving at a high speed in a reverse access channel is improved.

In order to solve the above technical problem, an embodiment of the present invention provides a method for initiating a reverse access, where at least two speed ranges and signature sequence groups corresponding to the speed ranges are preset;

the wireless terminal determines the speed range according to the self moving speed, selects a signature sequence from the signature sequence group corresponding to the speed range, generates a reverse access prefix according to the signature sequence and sends the reverse access prefix to the network side.

The embodiment of the invention also provides a method for detecting reverse access, which presets at least two speed ranges and signature sequence groups respectively corresponding to the speed ranges;

and the network side detects the reverse access prefixes generated by each signature sequence group corresponding to each speed range by using different block modes, wherein the higher the speed range is, the smaller the block mode is, and the number of blocks is more than or equal to 1.

The embodiment of the invention also provides a method for initiating reverse access, which comprises the following steps:

the wireless terminal repeats the short signature sequence at least once in the time domain to generate a reverse access prefix and send the reverse access prefix to a network side;

the length of the short signature sequence is determined by the maximum moving speed of the wireless terminal supported by the network side, and the length of the short signature sequence is shorter when the maximum moving speed is higher.

presetting at least two distance ranges or speed ranges, wherein each distance range or speed range corresponds to a different reverse access prefix structure;

the wireless terminal determines the distance range according to the distance between the wireless terminal and the base station, or determines the speed range according to the moving speed of the wireless terminal, and generates a reverse access prefix according to the distance range or the structure corresponding to the speed range and sends the reverse access prefix to the network side.

The embodiment of the invention also provides a method for detecting reverse access, which comprises the following steps:

presetting at least two distance ranges or speed ranges, wherein each distance range or speed range corresponds to different resource ranges and different reverse access prefix structures respectively;

the network side determines the distance range or the speed range of the wireless terminal which sends the reverse access prefix according to the resource range of the resource which transmits the reverse access prefix, and detects the reverse access prefix according to the reverse access prefix structure corresponding to the distance range or the speed range.

An embodiment of the present invention further provides a wireless terminal, including:

a unit for storing at least two speed ranges and signature sequence groups respectively corresponding to the speed ranges;

a group selecting unit for determining the speed range according to the moving speed of the wireless terminal and selecting the corresponding signature sequence group according to the speed range;

a code selecting unit that selects one signature sequence from the selected signature sequence group;

and a sending unit for generating a reverse access prefix according to the selected signature sequence and sending the reverse access prefix to a network side.

The embodiment of the present invention further provides a network side device, including:

a storage unit for storing at least two speed ranges and signature sequence groups respectively corresponding to the speed ranges;

a receiving unit for receiving a reverse access prefix signal from a wireless terminal;

a block detection unit for detecting the reverse access prefix signal received by the receiving unit in a block mode;

the reverse access prefixes generated by the signature sequence groups corresponding to the speed ranges are detected by using different block modes, the higher the speed range is, the smaller the block mode is, and the number of the blocks is more than or equal to 1.

The technical scheme of the invention is mainly different from the prior art in that signature sequences are grouped, different signature sequence groups are used in different speed ranges, and a network side receives the high-speed signature sequence groups in a blocking mode, so that the packet loss rate of reverse access of the high-speed wireless terminal is reduced, and the performance of a reverse access channel is improved.

The signature sequence groups in different speed ranges are detected by different block modes, the signature sequence group in the lowest speed is not detected by the block mode, and the signature sequence group in the higher speed is detected by smaller blocks, so that the block size is suitable for the change condition of reverse channels in different speeds, and the best effect is achieved.

The signature sequences in the signature sequence group corresponding to different speed ranges are different in length, the signature sequence corresponding to a higher speed range is shorter, the wireless terminal repeats the selected short signature sequence on a time domain for multiple times to generate a long reverse access prefix, the repetition times are related to the length of the signature sequence, the longer the signature sequence is, the fewer the repetition times are, and the finally generated access prefixes are the same in length; the network side carries out blocking according to the repeated times, so that the size of the blocking corresponds to the length of the signature sequence, and each signature sequence in the prefix is taken as a unit for carrying out correlation detection, so that the best effect is achieved during detection.

Only one signature sequence group is used for carrying out related detection on each block mode, so that the detection efficiency is improved.

The blocks can be overlapped with each other, and the accuracy of block detection is improved.

Shorter signature sequences can be selected for wireless terminals which are closer to the base station, so that the detection performance of the wireless terminal which moves at a high speed in the center of the cell is improved.

Longer signature sequences can be selected for wireless terminals far away from the base station, so that the defect of limited terminal power is overcome, and the coverage range of signals is improved. The longer signature sequences are grouped according to the speed range so as to be received by different block modes at the network side, thereby further improving the success rate of reverse access of the wireless terminal far away from the base station when the wireless terminal moves at high speed.

The selected signature sequence is modulated and transmitted after being interleaved, thereby improving the capability of resisting channel time selectivity attenuation and frequency selectivity attenuation.

The wireless terminal divides the signature sequence into blocks, and interleaves each block independently, and the interleaving modes for each block can be the same or different and respectively represent different signature sequences. The network side tries to perform deinterleaving by using various possible deinterleavers, and knows the interleaving mode used by the wireless terminal, so that different signature sequences are distinguished by different interleaving modes.

The network side allocates different transmission resources, such as frequency resources and/or time slot resources and/or spread spectrum code resources, for different speed ranges or different distances from the base station, and distinguishes wireless terminals in different speed ranges or different distances according to the transmission resources, and directly adopts a corresponding block mode for detection, thereby simplifying the detection operation of the network side.

The network side detects the received reverse access prefix in a blocking mode and a whole block mode respectively, and if any one of detection energy of the blocking detection or the whole block detection exceeds a judgment threshold value, the network side is considered to capture the reverse access prefix. By detecting the two methods, the wireless terminals with different moving speeds can be better met, when the moving speed of the terminal is higher, the detection effect can be improved by overlapping and partitioning detection, when the moving speed of the terminal is lower, a better detection effect can be obtained by integral detection, the packet loss rate of reverse access of the wireless terminal can be reduced by detecting from two aspects, and the performance of a reverse access channel is improved.

The wireless terminals with different distances from the base station or the wireless terminals with different moving speeds adopt reverse access prefixes with different protection time and different cyclic prefix lengths, so that the cyclic prefix sent by the wireless terminal far away from the base station can better keep orthogonality, and the access success rate of the part of terminals is improved.

Drawings

Fig. 1 is a diagram illustrating transmission of reverse access prefixes in the prior art;

fig. 2 is a diagram illustrating the reception of a reverse access prefix in the prior art;

fig. 3 is a flow chart of a method of initiating and detecting reverse access according to a first embodiment of the present invention;

fig. 4 is a schematic diagram illustrating transmission of a reverse access prefix in the method for initiating and detecting reverse access according to the first embodiment of the present invention;

fig. 5 is a schematic diagram illustrating the reception of a reverse access prefix in the method for initiating and detecting a reverse access according to the first embodiment of the present invention;

fig. 6 is a flow chart of a method of initiating and detecting reverse access according to a second embodiment of the present invention;

FIG. 7 is a schematic diagram of an interleaver between scrambling and DFT according to a third embodiment of the present invention;

fig. 8 is a diagram of a interleaver between a Walsh code selector and scrambling in accordance with a third embodiment of the present invention;

FIG. 9 is a schematic diagram of a non-scrambled time-add interleaver according to a third embodiment of the present invention;

FIG. 10 is a comparison diagram of simulation results of the method for initiating and detecting reverse access according to the present invention and the prior art;

fig. 11 is a schematic diagram of detecting a reverse access prefix on a network side in a method for initiating and detecting a reverse access according to a tenth embodiment of the present invention;

fig. 12 is a schematic diagram of detecting a reverse access prefix on a network side in a method for initiating and detecting a reverse access according to an eleventh embodiment of the present invention;

fig. 13 is a flowchart of a method of initiating and detecting reverse access according to a twelfth embodiment of the present invention;

fig. 14 is a schematic structural diagram of a wireless terminal according to a fifteenth embodiment of the present invention;

fig. 15 is a schematic diagram of a network-side device structure according to a sixteenth embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.

In the invention, signature sequences are grouped in advance, each signature sequence group corresponds to different speed ranges, a wireless terminal initiates reverse access by using the signature sequences in the corresponding signature sequence group according to the moving speed of the wireless terminal, and a network side detects and receives the high-speed signature sequence group in a blocking mode, thereby reducing the packet loss rate of the reverse access of the high-speed wireless terminal and improving the performance of a reverse access channel.

In the present invention, reverse access refers to access initiated from a terminal to a network side, and is also referred to as random access in some wireless communication systems.

A first embodiment of the present invention will be described below, which relates to a method for initiating and detecting reverse Access, and the mobile communication system in this embodiment is an Orthogonal Frequency Division Multiple Access (OFDMA) system, and a reverse Access prefix is transmitted on consecutive subcarriers of one physical frame (8 OFDM symbols).

In this embodiment, two speed ranges, a high speed range and a low speed range, are preset, and a speed threshold may be set, where the moving speed is greater than the threshold and belongs to the high speed range, and the moving speed is less than or equal to the threshold and belongs to the low speed range. Dividing the signature sequence into two groups, wherein the first group corresponds to the wireless terminal with the moving speed belonging to the altitude range; the second group corresponds to wireless terminals whose moving speed belongs to a low speed range. Assuming that the signature sequences are 1024-bit-long Walsh codes and the number of signature sequences is 1024, Walsh codes indexed 0 through 511 can be divided into a first signature sequence group and Walsh codes indexed 512 through 1023 into a second signature sequence group.

As shown in fig. 3, when the wireless terminal needs to transmit a prefix sequence, the method first proceeds to step 301, where a speed range is determined according to the moving speed of the wireless terminal itself, one signature sequence is selected from a signature sequence group corresponding to the speed range, and a reverse access prefix is generated according to the signature sequence and transmitted to the base station.

Specifically, as shown in fig. 4, a Walsh code group selector is used to select a corresponding signature sequence group according to the moving speed of the wireless terminal, and then a Walsh code selector is used to select an appropriate Walsh code from the selected signature sequence group according to the prior art, the selected Walsh code is scrambled by a scrambling code and arranged into a matrix of 128 rows and 8 columns, each column is subjected to 128-point DFT, and then mapped onto 128 subcarriers of OFDM, and then modulated by OFDM, and transmitted through an antenna. One Walsh code is sent over 8 OFDM symbols.

Wherein, the moving speed of the wireless terminal is the moving speed of the wireless terminal at the current moment or the average speed in the latest fixed-length time period. The current moving speed of the wireless terminal can be obtained by detecting the change speed of the downlink pilot frequency quality, or by a network assisted Global Positioning System (GPS), or other speed measurement methods.

Then, step 302 is entered, and at the receiving end, the base station needs to detect the reverse access prefixes generated by the signature sequence sets corresponding to different speed ranges in different manners. And a multi-block detection mode is adopted for a high-speed range, and a whole-block detection mode is adopted for a low-speed range. In this embodiment, both the whole block detection method and the multi-block detection method are referred to as block detection, where the whole block detection method is a specific example of block detection, that is, only one block is detected.

When the block detection method is adopted, as shown in fig. 5, firstly, OFDM demodulation (including cyclic prefix removal and 512-point FFT) and 128-point IDFT conversion are performed on a received signal (i.e., a reverse access prefix) by the prior art, and the demodulated reverse access prefix is continuously blocked according to a carried OFDM symbol, and the blocks can be overlapped with each other to improve the accuracy of block detection. For example, the reverse access prefix is transmitted on 8 consecutive OFDM symbols, and when the reverse access prefix is divided into blocks, the 1 st to 4 th symbols may be divided into a first block, the 3 rd to 6 th symbols may be divided into a second block, and the 5 th to 8 th symbols may be divided into a third block. Alternatively, when the blocks are divided, the blocks may be divided without overlapping. For example, the 1 st to 4 th symbols are directly divided into a first block, and the 5 th to 8 th symbols are divided into a second block. And then, respectively carrying out correlation detection on the prefix loaded on each block, and detecting to obtain the correlation energy of each block. In the correlation detection, only Walsh codes in the signature sequence group corresponding to the speed range are correlated. And then, carrying out joint judgment on the detection result through a judgment device, namely adding or averaging the correlation energy of each block obtained by detection, then comparing the correlation energy with a judgment threshold value, judging that the reverse access prefix is captured if the correlation energy is greater than the judgment threshold value, and otherwise, judging that the reverse access prefix is not captured.

In the detection of the reverse access prefix generated by the signature sequence group corresponding to the low-speed range, the received signal is subjected to OFDM demodulation (including cyclic embellishment and 512-point FFT) by the prior art, prefix data is extracted from eight continuous symbols of 128 subcarriers for transmitting the reverse access prefix, the prefix data is restored into a sequence of 1024 scrambled elements through 128-point IDFT conversion and rearrangement, and the sequence is subjected to descrambling and correlation detection. Unlike the prior art, in the present embodiment, correlation detection is performed using only Walsh codes in the signature sequence group corresponding to the low speed range. Similarly, if the detection signal is greater than the decision threshold, it is determined that the reverse access prefix is acquired, otherwise, it is determined that the reverse access prefix is not acquired.

In addition, in this embodiment, two or more speed ranges and signature sequence groups corresponding to the speed ranges may be provided, and the base station may perform detection using different block methods on reverse access prefixes generated by signature sequence groups corresponding to speed ranges other than the lowest speed range, wherein the higher speed range is detected using a smaller block method, so that the block size is suitable for the change situation of the reverse channel at different speeds, and the best effect is achieved. Three speed ranges can be set: a low speed range, a higher speed range, and a high speed range and their respectively corresponding set of signature sequences. When detecting reverse access, the base station may divide each 4 consecutive symbols of a reverse access prefix generated by the signature sequence group corresponding to the higher speed range into 1 block, perform correlation detection with the signature sequence group corresponding to the higher speed range, divide each 2 consecutive symbols of the reverse access prefix generated by the signature sequence group corresponding to the high speed range into 1 block, and perform correlation detection with the signature sequence group corresponding to the high speed range. Because only one signature sequence group is used for carrying out related detection on each blocking mode, the detection efficiency is improved.

In the present embodiment, the access prefix technology of different time domain lengths is transmitted in the center of a cell and at the edge of the cell in combination, so as to optimize the performance of the entire communication system.

In this embodiment, the signature sequences are divided into two types in advance, one is a long signature sequence, such as 1024-bit Walsh code, and the reverse access prefix generated according to the signature sequence occupies a longer time domain and is transmitted by being carried on 8 OFDM symbols; the other is a short signature sequence, such as 512-bit Walsh code, and the reverse access prefix generated from the signature sequence occupies a short time domain and can be transmitted over 4 OFDM symbols. The wireless terminal at the edge of the cell adopts the long signature sequence, and the prefix occupying more time slices can obtain larger detection energy, so that the base station can capture the prefix sequence, the defect of limited power of the wireless terminal can be overcome, and the coverage range of signals is improved. The wireless terminal in the center of the cell adopts the short signature sequence to reduce the influence of time selectivity attenuation, thereby improving the detection performance of the wireless terminal moving at high speed in the center of the cell.

The long signature sequences are further grouped in this embodiment, with different sets of signature sequences corresponding to different speed ranges.

As shown in fig. 6, when initiating a reverse access, the wireless terminal enters step 601, determines to use a long signature sequence or a short signature sequence according to a distance between the wireless terminal and a base station, and determines to use a short signature sequence if the distance between the wireless terminal and the base station is less than a preset threshold, if the wireless terminal is in the center of a cell, enters step 602, the wireless terminal selects a short signature sequence from a group of short signature sequences, generates a short reverse access prefix according to the signature sequence, and sends the short reverse access prefix to the base station. If the wireless terminal is at the edge of the cell, that is, the distance between the wireless terminal and the base station is greater than the preset threshold, step 603 is entered, the wireless terminal determines the speed range according to the moving speed, selects a long signature sequence from the signature sequence group corresponding to the speed range, generates a long reverse access prefix according to the signature sequence, and sends the long reverse access prefix to the base station. By the method, the access performance of the cell edge high-speed wireless terminal is optimized, and the coverage range of the cell edge low-speed wireless terminal is not influenced.

The distance of the wireless terminal from the base station can be obtained in various ways: one is obtained by measuring the strength of the pilot, because the farther the wireless terminal is from the base station, the weaker the pilot will be, the distance between the wireless terminal and the base station can be estimated by measuring the strength of the pilot; the other is that the current position is measured by a GPS device on the wireless terminal, and then the position of the base station is obtained from the broadcast information of the base station, and the distance between the wireless terminal and the base station can be calculated from the two positions.

Then, in step 604, at the receiving end, the base station performs detection on different signature sequence sets in different manners. The method comprises the following steps of detecting a short signature sequence group and a long signature sequence group corresponding to a low-speed range by directly using the mode of the prior art; and detecting the long signature sequence group corresponding to the high-speed range by using a block division mode. The block detection method can be referred to the first embodiment. The received signal may be detected by attempting with each signature sequence set, with the signature sequence with the largest coherent energy as the final result.

The third embodiment of the present invention also relates to a method for initiating and detecting reverse access, which is substantially the same as the first embodiment, and the difference is that in the present embodiment, after a signature sequence is selected, a wireless terminal interleaves the signature sequence during initiating reverse access, and then generates a reverse access prefix according to the interleaved signature sequence to transmit the reverse access prefix to a base station, thereby improving the capability of resisting channel time selectivity fading and frequency selectivity fading; accordingly, the base station needs to perform de-interleaving processing on the reverse access prefix before detecting the reverse access prefix. When interleaving a signature sequence to be block-detected, the wireless terminal interleaves each block using the same block-division method as that used by the network side. For example, in the high-speed range, since the signature sequence length is 1024 bits and the detection is performed in blocks of 512 bits on the network side, the signature sequences are also divided into two blocks of 512 bits on the radio terminal side, and the same interleaver is used for each block to perform interleaving. When interleaving is used, the blocks received at the network side may not overlap.

In practical application, an interleaver may be added after scrambling and before DFT to interleave the signature sequence, as shown in fig. 7; alternatively, the interleaver may be added after the Walsh code selector before scrambling, as shown in fig. 8; alternatively, if there is no scrambled portion, an interleaver is added between the Walsh code selector and the DFT, as shown in FIG. 9. The length of the interleaver may be identical to the size of the block detected by the block.

Fig. 10 shows a comparison of simulation results of the present invention and the prior art, where the curve with asterisks is the packet loss rate of the present invention and the curve with circles is the packet loss rate of the prior art. The packet loss rate is 10^-3In the scheme of the invention, the signal-to-noise ratio is higher than 1dB in the prior art, and therefore, by grouping the signature sequences, using different signature sequence groups in different speed ranges and receiving the high-speed signature sequence groups in a blocking mode at the network side, the packet loss rate of reverse access of the high-speed wireless terminal can be obviously reduced, and the performance of a reverse access channel is improved to a great extent. Wherein, the simulation conditions are as follows: moving speed of wireless terminal: 120 km/h; and (3) channel model: VA 120; false alarm probability: 0.1 percent.

A fourth embodiment of the present invention relates to a method for initiating and detecting reverse access, and is substantially the same as the third embodiment except that the third embodiment uses the same interleaver interleaving for different blocks in the same signature sequence, whereas the fourth embodiment uses the same or different interleaver interleaving for different blocks in the same signature sequence, and the interleavers used for different signature sequences may be different. For example, the signature sequence group includes a positive symmetric signature sequence AA and a negative symmetric signature sequence AB, where B ═ a and A, B respectively represent bit strings of a certain length. The same interleaver can be used for the front and back parts of AA and different interleavers can be used for the front and back parts of AB, so that AA and AB can be distinguished by the difference of the interleavers during detection.

When the network side carries out de-interleaving processing on the received reverse access prefix, all possible de-interleaving modes are respectively tried to carry out de-interleaving on different blocks.

Specifically, a 1024-bit Walsh code as a signature sequence is divided into two 512-bit code segments, and the two 512-bit code segments are interleaved by 512-point interleavers. After interleaving, the OFDM symbols are mapped to 4 consecutive OFDM symbols after DFT. The interleaving pattern of the interleaver that interleaves the two segments depends on the Walsh code being transmitted, and the same interleaver or different interleavers, each representing a different Walsh code, can be selected. For example, one interleaver is used for symmetric Walsh codes and another interleaver is used for anti-symmetric Walsh codes. I.e. using different interleavers. This has the advantage that different Walsh codes can be distinguished at the receiving end by different interleavers.

A fifth embodiment of the present invention is also directed to a method of initiating and detecting reverse access, and the present embodiment is substantially the same as the first embodiment except that in the first embodiment, all signature sequences in the signature sequence groups corresponding to different speed ranges are long signature sequences, in the present embodiment, a signature sequence in a signature sequence group corresponding to a lowest speed range is a long signature sequence, and signature sequences in signature sequence groups corresponding to other speed ranges are short signature sequences, wherein the higher the signature sequence in the signature sequence group corresponding to the speed range, the shorter the signature sequence in the signature sequence group corresponding to the speed range, the longer the reverse access prefix is generated by the wireless terminal in the long signature sequence group corresponding to the speed range from the selected long signature sequence; the wireless terminal with the speed range corresponding to the short signature sequence group repeats the selected short signature sequence on the time domain for multiple times to generate a long reverse access prefix; wherein, the long reverse access prefix generated by the short signature sequence is equal to the reverse access prefix generated by the long signature sequence. The network side continuously divides the reverse access prefix into blocks according to OFDM symbols according to the length and the repetition times of the received signature sequence, the reverse access prefix carried on each block corresponds to one signature sequence, and therefore, the correlation detection is carried out by taking each signature sequence in the prefixes as a unit, and the best effect is achieved during the detection. And averaging or summing the detection values of the plurality of signature sequences, comparing the detection values with a judgment threshold value, and judging that the reverse access prefix is captured if the detection values are greater than the judgment threshold value. Here, the reverse access prefix of the lowest speed range wireless terminal may be regarded as block detection in which the number of blocks is 1 or no block detection is performed.

The description will be given taking Walsh codes as the signature sequence as an example: two speed ranges, a high speed range and a low speed range are preset, wherein the low speed range corresponds to a long signature sequence group, signature sequences in the group are 1024-bit Walsh codes, the high speed range corresponds to a short signature sequence group, and the signature sequences in the group are 512-bit Walsh codes.

In practical applications, the wireless terminal corresponding to the high speed range is selected from the following Walsh codes Walsh₀ ⁵¹²，Walsh₁ ⁵¹²，Walsh₂ ⁵¹²，...，Walsh_Ns-1 ⁵¹²One of them is selected, and after the selected Walsh code is repeated for 1 time, the Walsh code whose length is 1024 bits, i.e. Walsh code is obtained₀ ¹⁰²⁴，Walsh₁ ¹⁰²⁴，Walsh₂ ¹⁰²⁴，...，Walsh_Ns-1 ¹⁰²⁴. And respectively modulating the first half part and the second half part of the repeated Walsh code with the length of 1024 bits to the first half part and the second half part of the reverse access prefix time domain signal, and transmitting the reverse access prefix time domain signal to a network side.

The remaining 512-bit Walsh codes are spread into 1024-bit subcodes, i.e., (Walsh)_Ns ¹⁰²⁴，Walsh_512+Ns ¹⁰²⁴)，(Walsh_Ns+1 ¹⁰²⁴，Walsh_512+Ns+1 ¹⁰²⁴)，(Walsh_Ns+2 ¹⁰²⁴，Walsh_512+Ns+2 ¹⁰²⁴)，...，(Walsh₅₁₁ ¹⁰²⁴，Walsh_512+511 ¹⁰²⁴). The wireless terminal corresponding to the low speed range selects one generated reverse access prefix from the 1024-bit sub-codes and transmits the reverse access prefix to the network side.

The number proportion of Walsh codes in the two signature sequence groups is determined by Ns. The length of the reverse access prefix generated after the 512-bit Walsh code is repeated is the same as that of the reverse access prefix generated by the 1024-bit Walsh code.

A sixth embodiment of the present invention relates to a method of initiating and detecting reverse access, and is substantially the same as the first embodiment except that in the first embodiment, signature sequences in the signature sequence group corresponding to different speed ranges are all long signature sequences, in the present embodiment, signature sequences in the signature sequence group corresponding to each speed range are short signature sequences, the wireless terminal generates a long reverse access prefix by repeating the selected short signature sequences a plurality of times in the time domain, and the generated long reverse access prefix has the same length as the reverse access prefix generated in the first embodiment.

In this embodiment, one short signature sequence group may be separately provided, and the length of the short signature sequence in the short signature sequence group may be the same as or different from that of the short signature sequence group corresponding to each speed range. According to the distance between the wireless terminal and the base station, if the distance between the wireless terminal and the base station is smaller than a preset threshold, if the wireless terminal is in the center of a cell, selecting a short signature sequence from the short signature sequence, generating a short reverse access prefix according to the short signature sequence, and sending the short reverse access prefix to a network side; if the distance between the wireless terminal and the base station is larger than the preset threshold, determining the speed range according to the self moving speed, selecting a short signature sequence from the signature sequence group corresponding to the speed range, and repeatedly generating a reverse access prefix to send the short signature sequence to the network side on the time domain.

A seventh embodiment of the present invention also relates to a method for initiating and detecting reverse access, which can be based on any one of the first to sixth embodiments, and in this embodiment, the network side further allocates the same frequency resource and/or timeslot resource and/or spreading code resource to the wireless terminals corresponding to the same speed range and/or the distance between the wireless terminals and the base station, according to the speed range corresponding to the wireless terminals and/or the distance between the wireless terminals and the base station. The wireless terminal sends the reverse access prefix through the corresponding frequency resource and/or time slot resource and/or spread spectrum code resource according to the speed range and/or the distance between the wireless terminal and the base station. The network side determines the speed range of the wireless terminal sending the reverse access prefix according to the frequency resource and/or the time slot resource and/or the spread spectrum code resource for transmitting the reverse access prefix, and detects the reverse access prefix by using the block mode corresponding to the speed range.

For example, a high-speed range and a low-speed range are currently set, a network side allocates a frequency 1 to a wireless terminal whose distance from a base station is smaller than a preset threshold, allocates a frequency 2 to a wireless terminal whose distance from the base station is greater than the preset threshold and corresponds to the high-speed range, allocates a frequency 3 to a wireless terminal whose distance from the base station is smaller than the preset threshold and corresponds to the low-speed range, and different wireless terminals transmit reverse access prefixes on corresponding frequencies according to the distance from the wireless terminals to the base station and the speed of the wireless terminals. The network side can adopt the detection mode of the prior art to the reverse access prefix received from the frequency 1 according to the transmission frequency; a multi-block detection mode is used for the reverse access prefix received from the frequency 2; for the reverse access prefix received from the frequency 3, a whole block detection mode is used. Specific blocking detection methods (including both multi-block and whole-block detection) can be seen in the first embodiment. In the embodiment, the network side can determine the adopted block detection mode without performing complex judgment, so that the detection operation of the network side is simplified.

In addition, in order to improve the resource utilization rate, the network side may periodically detect the utilization rate of the allocated resources of the wireless terminals with different speed ranges and/or different distances from the base station, and adjust and allocate frequency resources and/or timeslot resources and/or spreading code resources for the wireless terminals with different speed ranges and/or different distances from the base station.

An eighth embodiment of the present invention relates to a method for initiating and detecting a reverse access, and is substantially the same as the seventh embodiment except that in the present embodiment, a reverse access prefix generated from a signature sequence further includes a cyclic prefix and a guard time. Reverse access prefixes generated by wireless terminals corresponding to different speed ranges contain guard times of different lengths. Considering that the coverage area of the low-speed user is generally required to be higher by the system, the reverse access prefix generated by the wireless terminal corresponding to the higher speed range may include a shorter guard time, and the reverse access prefix generated by the wireless terminal corresponding to the lower speed range may include a longer guard time. Or, considering that the propagation delay spread of the wireless terminal is large when the speed of the wireless terminal is high, the reverse access prefix generated by the wireless terminal corresponding to the higher speed range may include a longer guard time, and the reverse access prefix generated by the wireless terminal corresponding to the lower speed range may include a shorter guard time.

A ninth embodiment of the present invention relates to a method for initiating and detecting a reverse access in the same manner, and the present embodiment is substantially the same as the eighth embodiment. The difference is that in the eighth embodiment, the reverse access prefixes generated by the wireless terminals corresponding to different speed ranges include guard times of different lengths; in the present embodiment, the reverse access prefixes generated by the wireless terminals having different distances from the base station include guard times and cyclic prefixes having different lengths.

If the distance between the wireless terminal and the base station is greater than the preset threshold, the protection time and the cyclic prefix contained in the reverse access prefix generated by the wireless terminal are longer; if the distance between the wireless terminal and the base station is less than the preset threshold, the protection time and the cyclic prefix contained in the reverse access prefix generated by the wireless terminal are shorter.

A tenth embodiment of the present invention is directed to a method of initiating and detecting reverse access. In this embodiment, wireless terminals with different moving speeds select signature sequences from the same signature sequence group, the signature sequences in the signature sequence group are short signature sequences, and different wireless terminals randomly select different short signature sequences. And repeating the selected short signature sequence on the time domain for multiple times to generate a reverse access prefix and sending the reverse access prefix to the network side. The length of the short signature sequence is determined by the maximum moving speed which needs to be supported by the network side under certain target performance, and the larger the maximum moving speed is, the shorter the length of the short signature sequence is. The repetition times of the short signature sequence in the time domain is determined by the length of the short signature sequence, the shorter the length of the short signature sequence is, the larger the repetition times is, and the lengths obtained after the short signature sequences with different lengths are repeated in the time domain are the same, and are usually 1024 bits.

For example, the short signature sequence in the signature sequence group has a length of 512 bits, and the short signature sequence may be a 512-bit Walsh code, a GCL code, or a CAZAC code, and the wireless terminal repeats the short signature sequence twice to form 1024 bits, and generates a reverse access prefix from the 1024-bit repeated signature sequence and transmits the reverse access prefix to the network side. Alternatively, the short signature sequence may be the first 512 Walsh codes in a Walsh code group having a length of 1024 bits, and since the first 512 bits and the last 512 bits of each Walsh code are symmetrical among the first 512 Walsh codes, which is equivalent to repeating the 512-bit Walsh codes once, the short signature sequence can be directly used.

On the network side, as shown in fig. 11, the base station detects the received reverse access prefix in a non-overlapping block manner and a whole block manner, and if any detection energy in the detection results obtained by the non-overlapping block detection or the whole block detection exceeds the decision threshold, it is considered that the reverse access prefix is captured. In the detection of non-overlapping block mode, the base station firstly carries out continuous block division on the reverse access prefix according to OFDM symbols, all blocks are not overlapped, the reverse access prefix carried on each block is respectively subjected to relevant detection, the detected relevant energy of each block is added or averaged and then compared with a decision threshold value, and if the energy is greater than the decision threshold value, the reverse access prefix is determined to be captured. The detection in the monoblock mode can be regarded as a special case of the detection in the block mode, the base station does not need to block the reverse access prefix, and directly carries out related detection on the reverse access prefix, and if the detected related energy is greater than a judgment threshold value, the reverse access prefix is judged to be captured. By detecting the two methods, the wireless terminals with different moving speeds can be better met, when the moving speed of the terminal is higher, the detection effect can be improved by overlapping and partitioning detection, when the moving speed of the terminal is lower, a better detection effect can be obtained by integral detection, the packet loss rate of reverse access of the wireless terminal can be reduced by detecting from two aspects, and the performance of a reverse access channel is improved.

In order to improve the capability of resisting channel time selectivity fading and frequency selectivity fading, in this embodiment, the wireless terminal may also interleave the short signature sequence first, and then generate a reverse access prefix according to the interleaved short signature sequence to send to the network side, where the interleaving manners for different short signature sequences are the same or different. The wireless terminal may interleave after repeating the short signature sequence or before repeating.

Correspondingly, before the base station performs block-mode detection or whole-block-mode detection on the reverse access prefix, the reverse access prefix needs to be de-interleaved first.

An eleventh embodiment of the present invention is substantially the same as the tenth embodiment, and in the eleventh embodiment, a wireless terminal of different speed randomly selects a signature sequence from the same signature sequence group as well, but differs from the tenth embodiment in that the signature sequence in the signature sequence group is a short signature sequence, and the wireless terminal generates a reverse access prefix by repeating the short signature sequence a plurality of times in the time domain; in the present embodiment, the signature sequences in the signature sequence group are long signature sequences and are not required to have a repetitive structure. For example, all Walsh codes in the set of Walsh codes of length 1024. The wireless terminal may generate the reverse access prefix directly from the selected signature sequence.

On the network side, as shown in fig. 12, the base station detects the received reverse access prefix in an overlapping block manner and a whole block manner, and if any of the detection energies obtained by the overlapping block detection or the whole block detection exceeds a judgment threshold, it is considered to capture the reverse access prefix. Through two detection methods, different moving speeds of the wireless terminal can be well adapted, when the moving speed of the terminal is high, the detection effect can be improved through overlapped block detection, when the moving speed of the terminal is low, a better detection effect can be obtained through whole block detection, the packet loss rate of reverse access of the wireless terminal can be reduced through detection in two aspects, and the performance of a reverse access channel is improved.

A twelfth embodiment of the present invention is directed to a method of initiating and detecting reverse access. In this embodiment, at least two distance ranges are preset, and each distance range corresponds to a different length of the guard time and the cyclic prefix, and a different resource range. Wherein, the farther the distance range from the base station, the longer the guard time and the cyclic prefix. The resource range may be a range of frequency resources, a range of time slot resources, or a range of spreading code resources.

As shown in fig. 13, when the wireless terminal needs to initiate a reverse access, step 1301 is entered, and the wireless terminal determines a distance range according to a distance between itself and the base station. The wireless terminal can obtain the current position of the wireless terminal according to the global positioning system, and then calculate the distance between the wireless terminal and the base station according to the base station position obtained from the base station broadcast; alternatively, the distance between the wireless terminal and the base station is obtained by measuring the strength of the pilot.

Then, step 1302 is entered, and a reverse access prefix is generated by using the cyclic prefix and the guard time with the length corresponding to the distance range. Because the longer the protection time and the longer the cyclic prefix corresponding to the distance range from the base station, the wireless terminal far away from the base station can well keep the orthogonality of the reverse access prefix, and the interference in the transmission process is avoided.

Then, step 1303 is entered, the wireless terminal sends the generated reverse access prefix to the network side through the transmission resource in the resource range corresponding to the distance range where the wireless terminal is located.

Then, step 1304 is performed, in which the network side determines a distance range in which the wireless terminal transmitting the reverse access prefix is located according to a resource range in which the resource transmitting the reverse access prefix is located, and detects the reverse access prefix according to the guard time and the cyclic prefix length corresponding to the distance range.

In order to improve the resource utilization rate, the network side can detect the resource utilization rates of the wireless terminals in different distance ranges at regular time and adjust the resource ranges corresponding to the distance ranges. For example, if there are fewer wireless terminals in a distance range closer to the base station and the resource utilization rate is low, the resource range can be reduced, and the part of resources can be allocated to a distance range farther from the base station, thereby avoiding the vacancy of transmission resources.

A thirteenth embodiment of the present invention is directed to a method of initiating and detecting a reverse access, which is substantially the same as the twelfth embodiment except that in the thirteenth embodiment, different distance ranges correspond to different lengths of guard time and cyclic prefix; in the present embodiment, the different distance ranges correspond to different modulation schemes on the physical channel, for example, the wireless terminal in the distance range closer to the base station adopts the CDMA modulation scheme, and the wireless terminal in the distance range farther from the base station adopts the OFDMA modulation scheme, so as to improve the orthogonality of the reverse access prefix and increase the access success rate.

A fourteenth embodiment of the present invention is directed to a method for initiating and detecting a reverse access, which is substantially the same as the twelfth or thirteenth embodiment except that different distance ranges are preset in the twelfth or thirteenth embodiment, and different speed ranges are preset in the present embodiment, and each distance range corresponds to a guard time and a cyclic prefix with different lengths, or corresponds to a different physical channel modulation method. The wireless terminals with different moving speeds generate reverse access prefixes with different protection time and cyclic prefix lengths to be sent to the network side, or the reverse access prefixes are modulated on a physical channel through different modulation modes to be sent to the network side.

Wherein, the moving speed of the wireless terminal is the moving speed of the wireless terminal at the current moment or the average speed in the latest fixed-length time period.

A fifteenth embodiment of the present invention relates to a wireless terminal, as shown in fig. 14, including a storage unit configured to store at least two speed ranges and signature sequence groups respectively corresponding thereto; the group selection unit is used for determining the speed range according to the moving speed of the wireless terminal and determining the corresponding signature sequence group according to the speed range; a code selection unit for selecting one signature sequence from the determined set of signature sequences; a scrambling unit, which is used for scrambling the selected signature sequence; and a sending unit, configured to generate a reverse access prefix according to the scrambled signature sequence and send the reverse access prefix to the network side. By using different signature sequence groups according to different moving speeds, the network side can receive the high-speed signature sequence group in a blocking mode, so that the packet loss rate of reverse access of the high-speed wireless terminal is reduced, and the performance of a reverse access channel is improved.

Besides the above several main functional units, the transmitting unit also includes DFT module and OFDM modulator, and a scrambling unit is connected in series between the code selecting unit and the DFT module for scrambling the selected signature sequence.

In the present embodiment, the signature sequence in the signature sequence group corresponding to each speed range stored in the storage unit is a long signature sequence. The storage unit may further store a short signature sequence group including at least one short signature sequence.

If the storage unit stores the short signature sequence group, when the distance between the wireless terminal and the base station is larger than a preset threshold, the group selection unit determines the speed range according to the moving speed of the wireless terminal and selects the corresponding signature sequence group according to the speed range. When the distance between the wireless terminal and the base station is smaller than a preset threshold, the group selection unit selects the short signature sequence group, so that the detection performance of the wireless terminal moving at a high speed in the center of the cell is improved.

Or the signature sequences in the signature sequence group corresponding to each speed range are short signature sequences; the sending unit sends the selected short signature sequence to the network side by repeating the multiple growing reverse access prefixes in the time domain.

Or the signature sequence in the signature sequence group corresponding to the lowest speed range is a long signature sequence, and the signature sequences in the signature sequence groups corresponding to other speed ranges are short signature sequences, wherein the signature sequences in the signature sequence group corresponding to the higher speed range are shorter. The sending unit generates a long reverse access prefix according to the selected long signature sequence and sends the long reverse access prefix on the network side when the speed range of the wireless terminal corresponds to the long signature sequence group; when the speed range of the wireless terminal corresponds to the short signature sequence group, the selected short signature sequence is repeatedly grown for multiple times in the time domain to send a reverse access prefix to a network side; wherein, the long reverse access prefix generated by the short signature sequence is equal to the reverse access prefix generated by the long signature sequence.

In response to the second or third case, the storage unit may also store a short signature sequence group including at least one short signature sequence, where the short signature sequence in the short signature sequence group is used to generate the short reverse access prefix. If the distance between the wireless terminal and the base station is greater than the preset threshold, the group selection unit determines the speed range according to the moving speed of the wireless terminal, and selects the corresponding signature sequence group according to the speed range, the code selection unit selects one signature sequence from the corresponding signature sequence group, and the sending unit generates a long reverse access prefix according to the selected signature sequence and sends the long reverse access prefix to the network side; if the distance between the wireless terminal and the base station is less than the preset threshold, the group selection unit selects the short signature sequence group, the code selection unit selects a short signature sequence from the corresponding short signature sequence group, and the sending unit generates a short reverse access prefix according to the selected short signature sequence and sends the short reverse access prefix to the network side.

In this embodiment, the transmitting unit may further include a cyclic prefix and a guard time in the reverse access prefix generated from the signature sequence.

Considering that the coverage area of the low-speed user is generally required to be higher by the system, the protection time included in the reverse access prefix generated by the wireless terminal corresponding to the higher speed range can be made shorter, and the protection time included in the reverse access prefix generated by the wireless terminal corresponding to the lower speed range can be made longer.

Or, considering that the propagation delay spread of the wireless terminal is large when the speed of the wireless terminal is high, the protection time included in the reverse access prefix generated by the wireless terminal corresponding to the higher speed range may be longer, and the protection time included in the reverse access prefix generated by the wireless terminal corresponding to the lower speed range may be shorter.

Or, if the distance between the wireless terminal and the base station is greater than the preset threshold, the protection time and/or cyclic prefix contained in the reverse access prefix generated by the wireless terminal is longer; and if the distance between the wireless terminal and the base station is less than the preset threshold, the reverse access prefix generated by the wireless terminal contains shorter protection time and/or cyclic prefix.

In addition, the storage unit of the wireless terminal may further store different frequency resources and/or time slot resources and/or spreading code resources allocated by the network side to wireless terminals with different speed ranges and/or different distances from the base station according to the speed range corresponding to the wireless terminal and/or the distance from the wireless terminal to the base station. And the transmitting unit transmits the reverse access prefix of the wireless terminal through corresponding frequency resources and/or time slot resources and/or spread spectrum code resources according to the speed range of the wireless terminal and/or the distance between the wireless terminal and the base station.

In the wireless terminal according to this embodiment, an interleaver may be connected in series between the code selection unit and the transmission unit, and used to interleave the selected signature sequence. The transmitting unit generates a reverse access prefix according to the interleaved signature sequence and transmits the reverse access prefix to the network side, so that the capacity of resisting channel time selectivity attenuation and frequency selectivity attenuation is improved.

A sixteenth embodiment of the present invention relates to a network-side device including, as shown in fig. 15, a storage unit that stores at least two speed ranges and signature sequence groups respectively corresponding thereto; a receiving unit for receiving a reverse access prefix signal from a wireless terminal; and a block detection unit for detecting the reverse access prefix signal received by the receiving unit in a block mode. The high-speed signature sequence group is received in a blocking mode, so that the packet loss rate of reverse access of the high-speed wireless terminal is reduced, and the performance of a reverse access channel is improved. The reverse access prefixes generated by the signature sequence groups corresponding to the speed ranges except the lowest speed range are detected by using different block modes, and the higher speed range is detected by using the smaller block mode, so that the block size is suitable for the change situation of the reverse channel at different speeds, and the best effect is achieved.

Wherein, the block detection unit further comprises: a block module for continuously blocking the reverse access prefix according to OFDM symbols; a block detection module for respectively carrying out relevant detection on the reverse access prefix loaded on each block; and the judgment module is used for comparing the detected correlation energy of each block after adding or averaging the correlation energy with a judgment threshold value, and judging that the reverse access prefix is captured if the comparison result is greater than the judgment threshold value.

The receiving unit also comprises an OFDM demodulator and an IDFT module, wherein the OFDM demodulator performs OFDM demodulation on the received signals and then transmits the signals to the IDFT module for inverse discrete Fourier transform and then outputs the signals.

And also contains a descrambling unit and a de-interleaver, and performs the reverse operation of the scrambling unit and the interleaver in the wireless terminal.

In addition to the above main units, the network side device of this embodiment may further include a deinterleaving unit configured to deinterleave the reverse access prefix signal received by the receiving unit and output the deinterleaved reverse access prefix signal to the block detection unit.

There may also be the following: in the storage unit, the signature sequence in the signature sequence group corresponding to the lowest speed range is a long signature sequence, and the signature sequences in the signature sequence groups corresponding to the other speed ranges are short signature sequences, wherein the signature sequences in the signature sequence group corresponding to the higher speed range are shorter.

And correspondingly, the blocking module continuously blocks the reverse access prefix according to the OFDM symbols according to the length and the repetition times of the signature sequence, so that the reverse access prefix carried on each block corresponds to one signature sequence, and the correlation detection is carried out by taking each signature sequence in the prefixes as a unit, thereby achieving the best effect during the detection.

In addition, the receiving unit may also determine a speed range in which the wireless terminal that transmits the reverse access prefix is located according to the frequency resource and/or the timeslot resource and/or the spreading code resource that transmits the reverse access prefix, and instruct the block detection unit to detect the reverse access prefix using a block method corresponding to the speed range. The corresponding block mode can be directly adopted for detection without other complex judgment, so that the detection operation of the network side is simplified.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

A seventeenth embodiment of the present invention is directed to a wireless terminal including: and repeating the short signature sequence at least once in the time domain to generate a reverse access prefix and sending the reverse access prefix to a network side. The length of the short signature sequence is determined by the maximum moving speed of the wireless terminal supported by the network side, and the length of the short signature sequence is shorter when the maximum moving speed is higher. The repetition times of the short signature sequence is determined by the length of the short signature sequence, the shorter the length of the short signature sequence is, the larger the repetition times is, and the lengths obtained after the short signature sequences with different lengths are repeated on a time domain are the same. By repeating the short signature sequence in the time domain, the phenomenon of antisymmetric front half and rear half of the signature sequence can be avoided, for example, in a 1024-bit Walsh code group, the first 512 bits and the second 512 bits of the latter 512 Walsh codes form antisymmetric, which easily causes that the network side cannot identify the reverse access prefix generated by the Walsh codes, and by repeating the short signature sequence in the time domain, the problem can be well solved, and the success rate of capturing the reverse access prefix by the network side is improved.

An eighteenth embodiment of the present invention relates to a network-side device including: a block detection unit for detecting the received reverse access prefix in a block mode; a whole block detection unit for detecting the received reverse access prefix in a whole block mode; and the judging unit judges that the reverse access prefix is captured when at least one detection result is greater than a judging threshold value according to the detection results of the blocking detection unit and the whole block detection unit. By detecting the two methods, the wireless terminals with different moving speeds can be better met, when the moving speed of the terminal is higher, the detection effect can be improved by overlapping and partitioning detection, when the moving speed of the terminal is lower, a better detection effect can be obtained by integral detection, the packet loss rate of reverse access of the wireless terminal can be reduced by detecting from two aspects, and the performance of a reverse access channel is improved.

Wherein, this blocking detecting element still contains: a block module for continuously blocking the reverse access prefix according to OFDM symbols; a module for respectively carrying out relevant detection on the reverse access prefix loaded on each block; and the module compares the detected correlation energy of each block with a judgment threshold value after adding or averaging, and judges that the reverse access prefix is captured if the correlation energy of each block is greater than the judgment threshold value.

In addition, the detection of the blocking mode can be the detection of a non-overlapping blocking mode, and when the blocking module carries out continuous blocking, all blocks are not overlapped; alternatively, the block-wise detection may be an overlapped block-wise detection, and when the block-wise module performs continuous block-wise division, the blocks may be overlapped with each other.

A nineteenth embodiment of the present invention relates to a wireless terminal including: the storage unit is used for storing at least two distance ranges, protection time and/or cyclic prefix lengths corresponding to the distance ranges, and resource ranges corresponding to the distance ranges; a distance detection unit for obtaining the current position of the wireless terminal according to the global positioning system and calculating the distance between the wireless terminal and the base station according to the base station position obtained from the base station broadcast; alternatively, the distance between the wireless terminal and the base station is obtained by measuring the strength of the pilot. And the transmitting unit is used for determining the distance range according to the distance between the wireless terminal and the base station, generating a reverse access prefix by adopting the protection time and/or the cyclic prefix with the length corresponding to the distance range and transmitting the reverse access prefix to the network side. The transmitting unit transmits the reverse access prefix through the transmission resource in the resource range corresponding to the distance range of the wireless terminal.

A twentieth embodiment of the present invention relates to a network-side device, including: the storage unit is used for storing at least two distance ranges, resource ranges respectively corresponding to the distance ranges, and protection time and/or length of a cyclic prefix respectively corresponding to the distance ranges; the judging unit is used for determining the distance range of the wireless terminal for transmitting the reverse access prefix according to the resource range of the resource for transmitting the reverse access prefix; and the detection unit is used for detecting the reverse access prefix according to the protection time and/or the cyclic prefix length corresponding to the distance range. Wherein the resource range may be a range of frequency resources, a range of time slot resources, or a range of spreading code resources.

In addition, in order to improve the resource utilization rate, the network side device further includes: and a unit for adjusting the resource range corresponding to each distance range according to the resource utilization rate of the wireless terminal in different distance ranges. For example, if there are fewer wireless terminals in a distance range closer to the base station and the resource utilization rate is low, the resource range can be reduced, and the part of resources can be allocated to a distance range farther from the base station, thereby avoiding the vacancy of transmission resources.

Claims

1. A method for initiating reverse access is characterized in that at least two speed ranges and signature sequence groups respectively corresponding to the speed ranges are preset;

2. The method of claim 1, wherein the moving speed of the wireless terminal is the moving speed of the wireless terminal at the current time or the average speed in the latest fixed-length time period.

3. The method according to claim 1, wherein the signature sequences in the signature sequence group corresponding to each speed range are long signature sequences, and a short signature sequence group including at least one short signature sequence is preset;

if the distance between the wireless terminal and the base station is greater than a preset threshold, determining the speed range according to the self moving speed, selecting a long signature sequence from a signature sequence group corresponding to the speed range, generating a reverse access prefix according to the signature sequence and transmitting the reverse access prefix to a network side;

if the distance between the wireless terminal and the base station is less than the preset threshold, selecting a short signature sequence from the short signature sequence group, generating a reverse access prefix according to the signature sequence and sending the reverse access prefix to the network side.

4. The method according to claim 1, wherein the signature sequences in the signature sequence group corresponding to each speed range are short signature sequences, and the wireless terminal repeats the selected short signature sequences at least once in time domain to generate a long reverse access prefix; or

The signature sequences in the signature sequence group corresponding to the lowest speed range are long signature sequences, and the signature sequences in the signature sequence groups corresponding to other speed ranges are short signature sequences, wherein the higher the signature sequences in the signature sequence group corresponding to the speed range, the longer the signature sequences in the signature sequence group corresponding to the speed range, the wireless terminal in the long signature sequence group corresponding to the speed range generates a long reverse access prefix according to the selected long signature sequences; the wireless terminal with the speed range corresponding to the short signature sequence group repeats the selected short signature sequence at least once in the time domain to generate a long reverse access prefix; wherein, the long reverse access prefix generated by the short signature sequence is equal to the reverse access prefix generated by the long signature sequence.

5. The method of initiating reverse access according to claim 4, wherein a short signature sequence group including at least one short signature sequence is further preset, and a reverse access prefix generated by a short signature sequence in the short signature sequence group is a short reverse access prefix;

if the distance between the wireless terminal and the base station is greater than a preset threshold, determining the speed range according to the self moving speed, selecting a signature sequence from a signature sequence group corresponding to the speed range, generating a long reverse access prefix according to the signature sequence, and sending the long reverse access prefix to a network side;

if the distance between the wireless terminal and the base station is smaller than the preset threshold, selecting a short signature sequence from the short signature sequence group, generating a short reverse access prefix according to the short signature sequence and sending the short reverse access prefix to a network side.

6. Method for initiating a reverse access according to claim 3 or 5, characterized in that the distance between the wireless terminal and the base station is obtained by:

the wireless terminal obtains the current position of the wireless terminal according to a global positioning system, and then calculates the distance between the wireless terminal and the base station according to the base station position obtained from the base station broadcast; or,

and obtaining the distance between the wireless terminal and the base station by measuring the strength of the pilot frequency.

7. The method of any of claims 1 to 5, wherein the wireless terminal selects the signature sequence, interleaves the signature sequence, generates a reverse access prefix according to the interleaved signature sequence, and transmits the reverse access prefix to the network side.

8. The method of claim 7, wherein when the wireless terminal interleaves the signature sequences, the wireless terminal partitions the signature sequences into blocks and then interleaves each block independently, wherein the interleaving manners for the blocks are the same or different, and the interleaving manners for different signature sequences are the same or different.

9. Method for initiating reverse access according to any of claims 1 to 5, wherein a cyclic prefix and/or a guard time is included in the reverse access prefix generated from the signature sequence.

10. The method of initiating reverse access of claim 9, wherein reverse access prefixes generated by wireless terminals corresponding to different speed ranges contain guard times of different lengths;

the reverse access prefix generated by the wireless terminal corresponding to the higher speed range contains shorter protection time, and the reverse access prefix generated by the wireless terminal corresponding to the lower speed range contains longer protection time; or

The reverse access prefix generated by the wireless terminal corresponding to the higher speed range contains a longer guard time, and the reverse access prefix generated by the wireless terminal corresponding to the lower speed range contains a shorter guard time.

11. The method of initiating reverse access according to claim 9, wherein the reverse access prefixes generated by the wireless terminals with different distances from the base station contain different lengths of guard time and/or cyclic prefix;

if the distance between the wireless terminal and the base station is greater than the preset threshold, the protection time and/or the cyclic prefix contained in the reverse access prefix generated by the wireless terminal is longer; and if the distance between the wireless terminal and the base station is less than the preset threshold, the reverse access prefix generated by the wireless terminal contains shorter protection time and/or cyclic prefix.

12. The method according to any of claims 1 to 5, wherein a network side allocates the same frequency resource and/or time slot resource and/or spreading code resource to the wireless terminals corresponding to the same speed range and/or the distance between the wireless terminals and the base station according to the speed range corresponding to the wireless terminals and/or the distance between the wireless terminals and the base station;

and the wireless terminal sends the reverse access prefix through corresponding frequency resources and/or time slot resources and/or spread spectrum code resources according to the speed range and/or the distance between the wireless terminal and the base station.

13. A method for detecting reverse access is characterized in that at least two speed ranges and signature sequence groups corresponding to the speed ranges are preset;

14. The method of claim 13, wherein the block-wise detecting comprises:

and continuously partitioning the reverse access prefix according to the orthogonal frequency division multiplexing symbol, respectively carrying out correlation detection on the reverse access prefix carried on each block, adding or averaging the correlation energy of each block obtained by detection, comparing the sum or average with a decision threshold value, and if the sum or average is greater than the decision threshold value, judging that the reverse access prefix is captured.

15. The method of claim 14, wherein the consecutive partitioning is performed with or without overlapping blocks.

16. The method of detecting reverse access according to claim 14,

in the preset speed range, the signature sequence in the signature sequence group corresponding to the lowest speed range is a long signature sequence, and the signature sequences in the signature sequence groups corresponding to other speed ranges are short signature sequences, wherein the signature sequence in the signature sequence group corresponding to the higher speed range is shorter;

and the network side continuously partitions the reverse access prefix into blocks according to the length and the repetition times of the signature sequence and the orthogonal frequency division multiplexing symbol, wherein the reverse access prefix carried on each block corresponds to one signature sequence.

17. The method according to any of claims 13 to 16, wherein the network side determines a speed range in which a wireless terminal transmitting the reverse access prefix is located according to frequency resources and/or timeslot resources and/or spreading code resources for transmitting the reverse access prefix, and detects the reverse access prefix by using a blocking manner corresponding to the speed range.

18. The method according to claim 17, wherein the network side adjusts and allocates frequency resources and/or time slot resources and/or spreading code resources for the wireless terminals with different speed ranges and/or different distances from the base station according to the utilization rate of the allocated resources.

19. Method for detecting reverse access according to any of claims 13 to 16, wherein a reverse access prefix is deinterleaved before said detection of the reverse access prefix.

20. The method of claim 19, wherein when de-interleaving the reverse access prefix, all possible de-interleaving manners are tried for different blocks to perform de-interleaving, and different signature sequences are distinguished by obtaining a successful de-interleaving manner.

21. A method for initiating reverse access, comprising the steps of:

22. The method of initiating reverse access according to claim 21,

the repetition times are determined by the length of the short signature sequence, the shorter the length of the short signature sequence is, the larger the repetition times is, and the lengths obtained after the short signature sequences with different lengths are repeated on the time domain are the same.

23. The method according to any of claims 21 or 22, wherein the wireless terminal interleaves the short signature sequence, and then generates a reverse access prefix according to the interleaved short signature sequence, and sends the reverse access prefix to the network side, wherein the interleaving manners for different short signature sequences are the same or different, and the wireless terminal performs the interleaving before repeating the short signature sequence or performs the interleaving after repeating the short signature sequence.

24. A method for initiating reverse access, comprising the steps of:

25. The method of claim 24, wherein the corresponding different reverse access prefix structure is one of the following or any combination thereof:

each distance range or speed range respectively corresponds to protection time with different lengths;

each distance range or speed range respectively corresponds to cyclic prefixes with different lengths;

each distance range or speed range corresponds to a different modulation scheme on the physical channel.

26. The method of initiating reverse access of claim 25, wherein each of the distance ranges or speed ranges corresponds to only one resource range;

and the wireless terminal sends the reverse access prefix through the transmission resource in the resource range corresponding to the distance range or the speed range in which the wireless terminal is positioned.

27. The method of initiating reverse access of claim 26, wherein the resource range is one of:

frequency resource range, time slot resource range, spreading code resource range.

28. Method for initiating reverse access according to claim 25, wherein the further distance from the base station corresponds to a longer guard time and/or cyclic prefix.

29. Method for initiating a reverse access according to any of the claims 25 to 28, characterised in that the distance between the wireless terminal and a base station is obtained by:

30. Method for initiating a reverse access according to any of claims 25 to 28, wherein the moving speed of the wireless terminal is the moving speed of the wireless terminal at the current moment or the average speed within the last fixed length time period.

31. A method for detecting reverse access, comprising the steps of:

presetting at least two distance ranges or speed ranges, wherein each distance range or speed range corresponds to a different resource range and a different reverse access prefix structure respectively;

32. The method of claim 31, wherein the corresponding different reverse access prefix structure is one of the following or any combination thereof:

33. The method of claim 32, wherein the resource range is one of:

34. The method according to any of claims 31 to 33, wherein the network side adjusts the resource range corresponding to each distance range or speed range according to the resource utilization rate of the wireless terminal in different distance ranges or speed ranges.

35. A wireless terminal, comprising:

36. The wireless terminal of claim 35, wherein the signature sequences in the signature sequence group corresponding to each speed range are long signature sequences;

the wireless terminal further includes:

a unit that stores a short signature sequence group including at least one short signature sequence;

the group selection unit is further configured to determine a speed range according to the moving speed of the wireless terminal if the distance between the wireless terminal and the base station is greater than a preset threshold, select the corresponding signature sequence group according to the speed range, and select the short signature sequence group if the distance between the wireless terminal and the base station is less than the preset threshold.

37. The wireless terminal of claim 35, wherein the signature sequences in the signature sequence group corresponding to each speed range are short signature sequences;

the sending unit is further configured to send the selected short signature sequence to the network side by repeating at least one secondary long reverse access prefix in the time domain.

38. The wireless terminal of claim 35, wherein the signature sequences in the signature sequence group corresponding to the lowest speed range are long signature sequences, and the signature sequences in the signature sequence groups corresponding to the other speed ranges are short signature sequences, wherein the higher the speed range, the shorter the signature sequences in the signature sequence group corresponding to the higher speed range;

the sending unit is further configured to generate a long reverse access prefix according to the selected long signature sequence and send the long reverse access prefix on the network side when the speed range in which the wireless terminal is located corresponds to the long signature sequence group; when the speed range of the wireless terminal corresponds to the short signature sequence group, the selected short signature sequence is repeated for at least one secondary growth reverse access prefix on the time domain and is sent to the network side; wherein, the long reverse access prefix generated by the short signature sequence is equal to the reverse access prefix generated by the long signature sequence.

39. The wireless terminal according to claim 37 or 38, wherein the wireless terminal further comprises:

a unit that stores a short signature sequence group including at least one short signature sequence, the short signature sequence in the short signature sequence group being used to generate a short reverse access prefix;

the group selection unit is also used for determining the speed range according to the moving speed of the wireless terminal if the distance between the wireless terminal and the base station is greater than a preset threshold, selecting the corresponding signature sequence group according to the speed range, and selecting the short signature sequence group if the distance between the wireless terminal and the base station is less than the preset threshold;

the sending unit is further configured to generate a long reverse access prefix according to the selected signature sequence and send the long reverse access prefix to the network side if the distance between the wireless terminal and the base station is greater than a preset threshold, and generate a short reverse access prefix according to the selected short signature sequence and send the short reverse access prefix to the network side if the distance between the wireless terminal and the base station is less than the preset threshold.

40. The wireless terminal according to any of claims 35 to 38, wherein an interleaver is further connected in series between the code selection unit and the transmission unit for interleaving the selected signature sequence.

41. The wireless terminal of claim 40, wherein the transmitting unit comprises a module for performing discrete Fourier transform and a module for performing orthogonal frequency division multiplexing modulation;

and a scrambling unit is also connected in series between the code selection unit and the sending unit and is used for scrambling the selected signature sequence.

42. The wireless terminal according to any of claims 35 to 38, wherein the transmitting unit is further configured to include a cyclic prefix and/or a guard time in a reverse access prefix generated according to a signature sequence;

The reverse access prefix generated by the wireless terminal corresponding to the higher speed range contains longer protection time, and the reverse access prefix generated by the wireless terminal corresponding to the lower speed range contains shorter protection time; or

43. The wireless terminal of any of claims 35-38, further comprising: a unit for receiving and storing different frequency resources and/or time slot resources and/or spread spectrum code resources allocated to the wireless terminals with different speed ranges and/or different distances from the base station by the network side according to the speed ranges corresponding to the wireless terminals and/or the distances from the wireless terminals to the base station;

the sending unit is further configured to send the reverse access prefix through a corresponding frequency resource and/or time slot resource and/or spreading code resource according to the speed range of the wireless terminal and/or the distance between the wireless terminal and the base station.

44. A network-side device, comprising:

45. The network-side device of claim 44, wherein the block detection unit comprises: a module for continuously partitioning the reverse access prefix according to the OFDM symbol; a module for respectively carrying out relevant detection on the reverse access prefix loaded on each block; the module compares the detected related energy of each block with a judgment threshold value after adding or averaging, and judges that the reverse access prefix is captured if the energy is greater than the judgment threshold value;

the receiving unit comprises an orthogonal frequency division multiplexing demodulator and an inverse discrete Fourier transform module, wherein the orthogonal frequency division multiplexing demodulator performs orthogonal frequency division multiplexing demodulation on a received signal and then delivers the signal to the inverse discrete Fourier transform module for inverse discrete Fourier transform and then outputs the signal.

46. The network-side device of claim 45, wherein, among the speed ranges and signature sequence groups stored in the storage unit, the signature sequence in the signature sequence group corresponding to the lowest speed range is a long signature sequence, and the signature sequences in the signature sequence groups corresponding to the other speed ranges are short signature sequences, wherein the signature sequences in the signature sequence group corresponding to the higher speed range are shorter;

the block detection unit also comprises a module for continuously blocking the reverse access prefix according to the orthogonal frequency division multiplexing symbol according to the length and the repetition times of the signature sequence, and the reverse access prefix carried on each block corresponds to one signature sequence.

47. The network-side device of claim 44, further comprising a unit configured to determine a speed range in which a wireless terminal transmitting the reverse access prefix is located according to frequency resources and/or time slot resources and/or spreading code resources for transmitting the reverse access prefix;

the block detection unit is further configured to detect the reverse access prefix using a block mode corresponding to the speed range.

48. The network-side device of claim 44, further comprising a deinterleaving unit, configured to deinterleave the reverse access prefix signal received by the receiving unit and output the deinterleaved signal to the block detection unit.

49. A wireless terminal, comprising:

a unit for repeating the short signature sequence at least once in time domain to generate reverse access prefix and sending the reverse access prefix to network side;

50. The wireless terminal of claim 49,

51. A wireless terminal, comprising:

a unit for storing at least two distance ranges or speed ranges and reverse access prefix structures respectively corresponding to the distance ranges or speed ranges;

a unit for determining a distance range according to a distance between the wireless terminal and the base station, or determining a speed range according to a moving speed of the wireless terminal;

and a unit for generating reverse access prefix according to the structure corresponding to the distance range or the speed range and sending the reverse access prefix to the network side.

52. The wireless terminal of claim 51, wherein the corresponding different reverse access prefix structures are one of the following or any combination thereof:

53. The wireless terminal of claim 51, further comprising:

a unit for storing the resource ranges corresponding to the distance ranges or the speed ranges;

and a unit for sending the reverse access prefix through the transmission resource in the resource range corresponding to the distance range or the speed range where the wireless terminal is located.

54. A network-side device, comprising:

a unit for storing at least two distance ranges or speed ranges and their respectively corresponding resource ranges;

a unit for storing the reverse access prefix structure corresponding to each distance range or speed range;

a unit for determining a distance range or a speed range of a wireless terminal transmitting the reverse access prefix according to a resource range of a resource transmitting the reverse access prefix;

and a unit for detecting the reverse access prefix according to the reverse access prefix structure corresponding to the distance range or the speed range.

55. The network-side device of claim 54, wherein the corresponding different reverse access prefix structures are one of the following or any combination thereof:

56. The network-side device of claim 54, further comprising: and a unit for adjusting the resource range corresponding to each distance range according to the resource utilization rate of the wireless terminal in different distance ranges.