阅读说明：本技术 封包侦测的软件定义无线电系统及封包侦测方法 (Software defined radio system for packet detection and packet detection method ) 是由 陈志楹 陈仁智 陈赞羽 何从廉 陈文江 于 2018-12-24 设计创作，主要内容包括：本公开提供一种封包侦测的软件定义无线电系统及封包侦测方法,该系统包括：一传送端,在传送信号前,分别配置一前缀同步信号及一后置同步信号于该信号的封包的起始位置及结束位置；以及一接收端,根据前缀与后置同步信号侦测封包是否存在空气中或是信道中,其中,当侦测到前缀同步信号时,接收端将该信号储存于存储器；当侦测到后置同步信号时,接收端停止将该信号储存于存储器,并将该信号传送至计算装置。(The present disclosure provides a packet detection software defined radio system and a packet detection method, the system including: a transmitting end, before transmitting the signal, respectively allocating a prefix synchronizing signal and a postamble at the start position and the end position of the packet of the signal; and a receiving end, detect whether the packet exists in the air or in the signal channel according to prefix and postamble, wherein, when detecting the prefix synchronizing signal, the receiving end stores the signal in the memorizer; when the post-synchronization signal is detected, the receiving end stops storing the signal in the memory and transmits the signal to the computing device.)

1. A packet-detection-based software defined radio system, comprising:

a transmitting end, which allocates a prefix synchronizing signal and a postamble to the initial position and the end position of the packet of the signal before transmitting the signal; and

and a receiving end for detecting the channel, wherein when the prefix synchronous signal is detected, the receiving end stores the signal in the memory, and when the postamble is detected, the receiving end stops storing the signal in the memory and transmits the signal to a computing device.

2. The system of claim 1 wherein the number of points of the prefix sync signal and the postamble is fixed and is not related to the transmission baud rate or the sampling rate set by the SDR.

3. The system of claim 2 wherein the maximum bandwidth occupied by the preamble synchronization signal and the postamble is defined as Bmax, and the bandwidth actually occupied by the preamble synchronization signal and the postamble is defined as B, r is B/Bmax, r is not related to the baud rate or the sampling rate set by the system.

4. The system of claim 1 wherein the sequences on the preamble and preamble are selected by a group identifier.

5. The system of claim 2 wherein the maximum bandwidth occupied by the preamble synchronization signal and the postamble is defined as Bmax, and the bandwidth actually occupied by the preamble synchronization signal and the postamble is defined as B, r ═ B/Bmax, r decreases as the baud rate or the sampling rate set by the system increases.

6. The system of claim 1, wherein the preamble synchronization signal and the preamble synchronization signal are composed of a plurality of N-point symbols concatenated together at the transmitter, wherein a plurality of sequences on the plurality of symbols are the same or different, and are selected by group identifiers; in the receiving end, the receiving end detects a first symbol in the plurality of symbols with the length of N points, when the detection is successful, the receiving end continues to detect a second symbol, when the detection is successful, whether the time difference between the second symbol and the first symbol is correct or not is judged, if the time difference is correct, the next symbol is detected sequentially, and the prefix synchronization signal or the postposition synchronization signal is not detected successfully until all the symbols are detected successfully.

7. A packet detection method for a software defined radio system, the method comprising:

before transmitting a signal, a transmitting end respectively allocates a prefix synchronous signal and a postamble synchronous signal at the initial position and the end position of a packet of the signal;

detecting a channel by a receiving end;

if the prefix synchronizing signal is detected, the receiving end is enabled to store the signal in a memory; and if the post-synchronization signal is detected, the receiving end stops storing the signal in the memory and transmits the signal to a computing device.

8. The method of claim 7 wherein the number of points of the prefix sync signal and the postamble is fixed and is not related to the transmission baud rate or the sampling rate set by the SDR.

9. The packet detection method of claim 8 wherein the maximum bandwidth occupied by the prefix sync signal and the postamble is defined as Bmax, and the bandwidth actually occupied by the prefix sync signal and the postamble is defined as B, r is B/Bmax, r is not related to the baud rate or the sampling rate set by the SDradio system.

10. The method of claim 7, wherein the sequences on the preamble and the preamble are selected by a group identifier.

11. The packet detection method of claim 8 wherein the maximum bandwidth occupied by the prefix sync signal and the postamble is defined as Bmax, and the bandwidth actually occupied by the prefix sync signal and the postamble is defined as B, r ═ B/Bmax, r decreases as the baud rate or the sampling rate set by the SDR increases.

12. The method of claim 7, wherein the preamble synchronization signal and the preamble synchronization signal are composed of N-point symbols in series, a plurality of sequences on the symbols are the same or different, and the sequences are selected by group identifiers; in the receiving end, the receiving end detects a first symbol in the plurality of symbols with the length of N points, when the detection is successful, the receiving end continues to detect a second symbol, when the detection is successful, whether the time difference between the second symbol and the first symbol is correct or not is judged, if the time difference is correct, the next symbol is detected sequentially, and the prefix synchronization signal or the postposition synchronization signal is not detected successfully until all the symbols are detected successfully.

Technical Field

The present disclosure relates to a software-defined radio (software-defined radio), and more particularly, to a preamble and postamble design for packet detection of a software-defined radio.

Background

Nowadays, software-defined radio (SDR) platforms are very popular in the market, and besides the SDR platforms can be directly connected to a computer, the SDR platforms can directly set various parameters through a software interface. In the transmitting mode, the format of the signal to be transmitted can be quickly defined by the writing of software or programs, while in the receiving mode, the calculation and processing procedures for the received signal can be directly defined in the software. The hardware part of the software defined radio platform comprises a front-end module (comprising a filter, a modulator/demodulator, a radio frequency module and the like) and a computer communication interface, so that a user can quickly construct a communication system without designing or realizing the front-end module, meanwhile, the design flexibility is kept, and programmable parameter setting of the front-end module can be reserved for the user to carry out customized definition on a software end.

Therefore, the software defined radio platform is well suited for applications such as baseband algorithm development, channel measurement, fast set-up of communication systems, etc., and offers a low cost and easy-to-handle option.

However, when developing a software-defined radio platform, it still retains the original advantages of a general software-defined radio, and at the same time, provides users with the development of program control, such as network communication protocol, handshake mechanism (handshaking) and automatic retransmission mechanism, in these program control applications, the software-defined radio must not only be able to receive and send signals, but also be able to detect and receive a complete packet, so as to correctly know the start and end positions of each packet, and the platform must also have duplex (duplex) capability, so the design and detection mechanism at the start and end of the packet is very important.

Disclosure of Invention

The present disclosure provides a Software Defined Radio (SDR) system for packet detection and a packet detection method suitable for the SDR.

The disclosed software defined radio system for packet detection comprises: a transmitting end, before transmitting the signal, respectively configuring a prefix synchronizing signal (preamble) and a postamble (postamble) at the start position and the end position of the packet of the signal; and a receiving end, detecting whether the packet exists in the air or in the channel according to the prefix and the post-synchronizing signal, when detecting the prefix synchronizing signal, the receiving end stores the signal in the memory, when detecting the post-synchronizing signal, the receiving end stops storing the signal in the memory and transmits the signal to a computing device.

According to the preferred embodiment of the present disclosure, the number of points of the prefix sync signal and the postamble signal is fixed and is not related to the transmission baud rate (baud-rate) or the sampling rate set by the software defined radio system. The maximum bandwidth occupied by the prefix sync signal and the postamble is defined as Bmax, and the bandwidth actually occupied by the prefix sync signal and the postamble is defined as B, and the preferred embodiment of the prefix sync signal and the postamble is designed as fixed B/Bmax. Referring to fig. 2, an implementation manner can be seen in that the prefix synchronization signal and the postamble are fixed to be N points, and by using the OFDM modulation method, the prefix synchronization signal and the postamble of N points can be generated by designing a sequence of M points to be placed on subcarriers representing different frequencies and then performing an IFFT of N points, and the same values of M and N are used for the transmission baud rate, the sampling rate, the carrier frequency, the transmission attenuation, and the reception gain set by the software-defined radio system. In the receiving end detection circuit, under different sampling rate settings, the same down sampling (down sampling) rate can be used for the prefix synchronization signal and the post synchronization signal, and then whether the down sampled synchronization signal exists in the received signal is detected, so that the same detection circuit can be used for detecting the prefix synchronization signal and the post synchronization signal under different sampling rate settings.

According to another preferred embodiment of the present disclosure, the number of points of the prefix sync signal and the postamble signal is fixed and is not related to the transmission baud rate or the sampling rate set by the software defined radio system. The maximum bandwidth occupied by the prefix sync signal and the postamble is defined as Bmax, and the bandwidth actually occupied by the prefix sync signal and the postamble is defined as B, and the preferred embodiment of the designed prefix sync signal and the postamble is not fixed as r ═ B/Bmax, but r decreases as the baud rate or the sampling rate set by the software defined radio system increases, or vice versa. Referring to fig. 5, an implementation manner may be shown in which the prefix synchronization signal and the postamble are fixed to be N points, and by using an OFDM modulation scheme, a sequence of M points is designed to be placed on subcarriers representing different frequencies, and then an IFFT of N points is performed to generate the prefix synchronization signal and the postamble of N points, where the value of M increases as the baud rate or the sampling rate set by the software defined radio system increases. In the receiving end detection circuit, the prefix synchronization signal and the post-synchronization signal are subjected to reduced sampling, and then whether the reduced-sampling synchronization signal exists in the received signal is detected, the supported reduced sampling multiplying power is different under different sampling rate settings, but the difference in the detection circuit design is very small, so that the detection efficiency can be kept by the lower reduced sampling multiplying power under the low sampling rate setting, and the reduced sampling multiplying power of the prefix synchronization signal can be further improved under the high sampling rate setting, so that the operation complexity of the detection circuit is reduced.

According to another preferred embodiment of the present disclosure, in the transmitting end, the prefix synchronization signal and the postamble may be composed of a plurality of symbols of length N point concatenated together, a plurality of sequences on the plurality of symbols may be the same or different, and the plurality of sequences are selected by group identification codes; in the receiving end, the receiving end detects the first symbol in the plurality of symbols with the length of N points, when the detection is successful, the receiving end continues to detect the second symbol, when the detection is successful, the time difference between the second symbol and the first symbol is judged whether to be correct, if so, the next symbol is continuously detected, and the detection is carried out in sequence, until all the plurality of symbols are successfully detected, the prefix synchronizing signal or the postposition synchronizing signal is successfully detected.

In addition, the packet detection method of the present disclosure includes the following steps: before transmitting a signal, a transmitting end respectively allocates a prefix synchronous signal and a postamble synchronous signal at the initial position and the end position of a packet of the signal; detecting whether the packet exists in the air or in a channel by the receiving end according to the prefix and the post-positioned synchronous signal; if the prefix synchronizing signal is detected, the receiving end is enabled to store the signal in a memory; and if the post-synchronization signal is detected, the receiving end stops storing the signal in the memory and transmits the signal to a computing device.

The packet detection method of the present disclosure may further include a group (groups) maximum support amount amplification method operating simultaneously, the amplification method including the steps of: in the transmitting end, the prefix synchronizing signal and the postamble can be composed of a plurality of symbols with length of N points which are connected in series, a plurality of sequences on the plurality of symbols can be the same or different, and the plurality of sequences are selected by group identification codes; and in the receiving end, the receiving end detects a first symbol in the plurality of symbols with the length of N points, when the detection is successful, the receiving end continues to detect a second symbol, when the detection is successful, whether the time difference between the second symbol and the first symbol is correct or not is judged, if so, the next symbol is detected sequentially until all the symbols are detected successfully, and the prefix synchronization signal or the post synchronization signal is detected successfully.

In order to make the aforementioned and other features and advantages of the disclosure more comprehensible, embodiments accompanied with figures are described in detail below. Additional features and advantages of the disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. The features and advantages of the disclosure will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the scope of the disclosure, as claimed.

Drawings

FIG. 1 is a diagram of a packet detection SOFC radio system according to the present disclosure;

fig. 2 shows a schematic diagram of a packet detection-based radio system (embodiment 1) according to the present disclosure;

fig. 3A, 3B, and 3C show the performance test results of example 1 of the present disclosure;

fig. 4 shows a block diagram of a detection circuit of a receiving end according to the present disclosure;

FIG. 5 is a block diagram of a packet detection-based radio system (embodiment 2) according to the present disclosure;

fig. 6A, 6B, and 6C show the performance test results of example 2 of the present disclosure;

FIG. 7 is a schematic diagram of the method for maximum support of groups (groups) in simultaneous operation according to the present disclosure (example 3);

FIG. 8A shows a block diagram of an amplification method of the present disclosure (example 3);

FIG. 8B shows a detection flow chart of the amplification method of the present disclosure (example 3); and

fig. 9A, 9B show comparative test results for false alarm rates with and without the amplification method of the present disclosure.

Description of the symbols

10,20,30 delivery end

12,22,32 receiving end

S70-S75 steps

Detailed Description

The embodiments of the present disclosure are described below with reference to specific embodiments, and those skilled in the art will readily appreciate that the advantages and features of the present disclosure can be implemented or applied by various embodiments without departing from the scope of the present disclosure.

The present disclosure provides a Software-Defined Radio (SDR) system for packet detection, so that the SDR can ensure that the entire packet data is received when receiving.

Fig. 1 shows the packet start and end formats of the present disclosure. At the transmitting end 10, the user-defined transmission signal (labeled data in fig. 1) is first transmitted with a sequence, called P1, and then a small blank is transmitted, which makes the P1 not interfere with the user signal due to multipath effect (multipath) in the receiving end, and also makes it possible to receive the complete user signal under the influence of channel effect and clock error at the transmitting end. After the user signal is transmitted, a small blank is also immediately followed, and finally a series of data is transmitted, called P2, the receiving end 12 detects P1 and P2 to know the start and end of the user signal, so as to store the complete user signal and provide the user with the processing at the software end. In addition, each of the platforms can provide users with the ability to independently set their group ID, sampling rate, carrier frequency, transmit attenuation, and receive gain parameters, and support one-to-many platform transmission, as well as provide simultaneous operation of multiple sets of receivers in communication.

As shown in fig. 1, the software defined radio system for packet detection provided by the present disclosure includes a transmitting end 10, before transmitting a signal (data), respectively allocating a preamble (preamble) P1 and a postamble (postamble) P2 at the start and end of the signal packet; and a receiving end 12, detecting whether the packet exists in the air or detects the channel according to the prefix and the postamble, wherein, when the prefix synchronizing signal P1 is detected, the receiving end 12 stores the signal in the memory; when the postamble P2 is detected, the receiver 12 stops storing the signal in the memory and transmits the signal to a computing device.

The software defined radio system for packet detection provided by the present disclosure includes two types of design structures of synchronization signals, which are detailed as follows:

(example 1)

As shown in fig. 2, the preamble sync signal and the postamble are both N-point symbols (symbols), and are composed of M-point sequences in frequency (the minimum frequency subcarrier is located at the center), and the same M and N values are used regardless of the parameter settings such as sampling rate, carrier frequency, transmission attenuation, and reception gain, and the content of the M-point sequences is only related to the group ID. The way of avoiding interference by the prefix synchronization signal between different groups can be divided into the following two cases:

(1) the prefix synchronization signals are distinguished by different sequences among groups with the same sampling rate, that is, the transmitting end 20 with group id a correspondingly uses the sequence x to form the prefix synchronization signals, if the group id is set as a, the receiving end 22 correspondingly uses the receiving end 22 formed by the sequence x to perform detection, the detection can be successful, and if the group id is set as b, the receiving end correspondingly uses the receiving end 22 formed by the sequence y to perform detection, the detection can not be successful, therefore, the prefix synchronization signals of the group id a can not cause false alarm to the group id b.

(2) The characteristics of the preamble synchronization signal structure will not affect each other among the groups with different sampling rates, i.e. the transmitting end 20 with the sampling rate f0 and the group id a corresponds to the group id consisting of the sequence x, and the receiving end 22 with the sampling rate f1 will not detect successfully even if the group id a corresponds to the group id consisting of the sequence x.

The design ensures that in all groups operating simultaneously, only the groups with the same sampling rate are required to be set with different group IDs to avoid signal mutual interference, and the groups with different sampling rates are not mistakenly alarmed, so that the total number of the groups operating simultaneously can be greatly increased. In addition, under any sampling rate setting, the receiving end 22 can support the prefix synchronization signal to perform matching detection after N/M times of reduction sampling, so that the same matching circuit can be used under different parameter settings, and M-point sequences are used at different sampling rates, so that the same sequence set can be shared, the complexity of the matching circuit can be reduced, and the memory requirement can be reduced.

Taking the practical situation as an example, if the software defined radio platform provides three sampling rates for the user to set: 30.72MHz, 61.44MHz, 122.88MHz, and up to 64, 50, 32 groups of three sampling rates may be simultaneously operating, respectively, while considering hardware cost, it is desirable that the clock of the matching hardware operate at 30.72MHz at the highest. By adopting the method of embodiment 1, when a Zadoff-Chu sequence is selected, at least a Zadoff-Chu sequence with a length of 64 is needed, 64 sequences can be provided by using different root indexes, that is, the group ID 0-63 of the corresponding group identification code can be set; since the highest sampling rate of 122.88MHz can be supported, and the highest operation clock of the matching hardware is 30.72MHz, the sub-sampling rate of the matching hardware is 122.88/30.72-4, so that the symbol length of the prefix synchronization signal is at least 64 × 4-256, therefore, M in fig. 2 is 64 and N is 256, the performance test of embodiment 1 is as shown in fig. 3A, 3B and 3C, fig. 3A shows that the match detection of the receiving end with 4 times of the sub-sampling rate in the same group correctly detects the prefix synchronization signal, fig. 3B shows that between two groups with the same sampling rate (two groups set different group identification codes, i.e. Zadoff-Chu sequences corresponding to different root indexes), the transmitting end causes the probability of false alarm of the receiving end of another group, fig. 3C shows that between two groups with different sampling rates (two groups set the same group identification code, i.e., Zadoff-Chu sequences corresponding to the same root index), the transmitting end causes a probability of false alarm at the receiving end of another group. Specifically, as shown in fig. 3A, it can be seen that the preamble synchronization signal can be detected completely and correctly at a signal-to-noise ratio (SNR) of more than-3 dB under various sampling rate settings, and is suitable for various communication related applications, such as synchronization mechanism, frequency offset, data encoding and decoding, etc., while fig. 3B shows that the influence of the preamble synchronization signal of other groups can be completely avoided by using different Zadoff-Chu sequences, and no false alarm occurs when the SNR is as low as-11 dB, and fig. 3C verifies the groups with different sampling rates, and does not affect each other even if the same Zadoff-Chu sequence is used. It should be noted that, referring to fig. 4, the prefix synchronization signal of the N point passes through the R-fold down-sampling circuit, the synchronization signal of the N/R point after down-sampling is obtained, and then the matching detection of the N/R point is used to detect whether the synchronization signal of the N/R point exists in the received signal, and for embodiment 1, N is 256, and three sampling rates are set: the detection circuits can be designed using R-4 for 30.72MHz, 61.44MHz, and 122.88MHz, so that the same set of detection circuits can be used for all sampling rate settings.

(example 2)

As shown in fig. 5, embodiment 2 of the present disclosure includes a transmitting end 30 and a receiving end 32, and regardless of the parameter setting, the prefix sync signal and the postamble are N-point symbols, and the sequence constituting the prefix sync signal covers a fixed bandwidth, so that the number of sequence points placed in the frequency range is different due to the sampling rate setting in embodiment 2. As shown in fig. 5, when the sequence length is M when the sampling rate is 61.44MHz, the sequence lengths arranged in frequency are 2M and M/2 when the sampling rates are set to 30.72MHz and 122.88MHz, respectively. The way of avoiding interference by the prefix synchronization signal between different groups can be divided into the following two cases:

(1) the prefix synchronization signals are distinguished by different sequences among groups with the same sampling rate.

(2) The characteristics of the preamble structure will not affect each other between groups with different sampling rates, and it is not necessary to use different sequences for distinguishing.

This design is the same as embodiment 1, and does not require additional sequences to avoid interference between groups of different sampling rates, thereby greatly increasing the total number of groups operating simultaneously. Under the higher sampling rate setting, the sub-sampling matching can provide a higher sub-sampling multiplying power than that in the embodiment 1, and the method is suitable for further reducing the hardware cost or supporting the higher sampling rate setting in the future; under the lower sampling rate setting, the sequence occupies a larger proportion of the total bandwidth, the matching noise can be reduced for the matching result of the receiving end 32, the method is suitable for operating in the environment with lower signal-to-noise ratio, the complexity of the matching circuit is originally lower, and the matching efficiency is not sacrificed due to the high-rate sub-sampling matching.

Taking the practical situation as an example, if the software defined radio platform provides three sampling rates for the user to set: 30.72MHz, 61.44MHz, 122.88MHz, and up to 64, 50, 32 groups of three sampling rates may be simultaneously operating, while considering hardware cost, it is desirable that the clock of the matching hardware operate at 15.36MHz at the highest. By adopting the method of embodiment 2, when selecting Zadoff-Chu sequences, three sampling rates are set to respectively require Zadoff-Chu sequences with lengths of 128, 64 and 32, each of which can support simultaneous operation of 128, 64 and 32 groups at most; since the highest sampling rate of 122.88MHz is supported, the highest operating clock of the matching hardware is 15.36MHz, the sub-sampling magnification of the matching hardware is 122.88/15.36-8, so that the symbol length of the prefix synchronization signal is at least 32 × 8-256, M in fig. 5 is 64, and N is 256, the performance test of embodiment 2 is as shown in fig. 6A, 6B, and 6C, fig. 6A shows the probability of correctly detecting the prefix synchronization signal in the same group, lists the performances of groups with sampling rates of 122.88MHz and 30.72MHz, the receiving end uses the sampling rate of 15.36MHz for matching detection, fig. 6B shows the probability of false alarm transmission caused by the other group between two groups with sampling rates of 122.88MHz (two groups set with different group IDs, i.e. Zadoff-Chu sequences corresponding to different root indexes), fig. 6C shows the probability of false alarm transmission caused by the other group between two groups with sampling rates of 122.88MHz and 30.72MHz (two groups set with the same identification code, i.e., the Zadoff-Chu sequences corresponding to the same root index, but the length of the Zadoff-Chu sequences used by the two is different due to different sampling rates), the transmitting end causes the probability of false alarm of the receiving end of the other group. Specifically, as shown in fig. 6A, it can be seen that the lower the sampling rate, the higher the proportion of the sequence in the total bandwidth, and the lower the matching noise, so that the sampling rate 30.72MHz can support the snr environment lower than the sampling rate 122.88MHz, but the case of the sampling rate 122.88MHz can support the matching detection with the sub-sampling rate as high as 8 times, and the snr range where the actual measurement result can be correctly detected can also be applicable to most of the communication related applications. FIG. 6B shows that different Zadoff-Chu sequences can completely avoid the influence of the prefix synchronization signal of other groups, while FIG. 6C verifies that the groups with different sampling rates will not influence each other even if the same root index Zadoff-Chu sequences with the same sequence bandwidth are used. It should be noted that, referring to fig. 4, the prefix synchronization signal of the N point passes through the R-fold down-sampling circuit, the synchronization signal of the N/R point after down-sampling is obtained, and then the matching detection of the N/R point is used to detect whether the synchronization signal of the N/R point exists in the received signal, and for the embodiment 2, N is 256, and three sampling rates are set: the detection circuit can be designed by using 2, 4 and 8R at 30.72MHz, 61.44MHz and 122.88MHz, when the sampling rate is set to 30.72MHz, R is smaller to obtain better detection performance, and when the sampling rate is set to 122.88MHz, R is 8 to reduce the operation clock of the detection circuit to 122.88/8 to 15.36MHz without the clock operating at 122.88MHz, thereby greatly reducing the operation complexity of the detection circuit.

(example 3)

In order to be suitable for various communication-related applications and support communication standards with higher data rates in the future, the software defined radio system of the present disclosure has a sampling rate that can be set by a user and will support a very high sampling rate, in which case the receiving end must perform sub-sampling matching with high rate, and in which case the length of the prefix synchronization signal is fixed, the higher the sub-sampling rate to be supported, the shorter the length of the sequence is configured in frequency, and thus the maximum number of groups capable of supporting simultaneous operation is reduced, and the lower the sequence occupies the total bandwidth, and further the matching noise of the receiving end is increased, which cannot be solved even if the length of the prefix synchronization signal is increased, and therefore, as shown in fig. 7, the present disclosure also provides a method for increasing the maximum support amount of simultaneous group operation, which can also use the design of embodiment 1 and embodiment 2 of the present disclosure, fig. 8A and 8B are a block diagram and a detection flowchart respectively illustrating a method for amplifying the maximum support of a group in simultaneous operation according to the present disclosure. The method comprises the following steps: if the length of the original prefix synchronous signal is N and the number of the sequence points placed on the frequency is M, M different sequences can be correspondingly generated to support the simultaneous operation of at most M groups, if the maximum group support number is desired to be amplified, L N points of the symbols with the same structure can be connected in series to form the prefix synchronous signal/post synchronous signal, the sequences on the L symbols can be the same or different, but are all selected from the original M different sequences, so that the prefix synchronous signal/post synchronous signal can support at most M different sequences^LThe groups operate simultaneously, firstlyThe parameter i is set to 1 (step S70), i.e., the matching is performed from the first symbol, so that the receiving end matches the first symbol first, after the matching is successful, the receiving end continues to match the second symbol (step S71), after the matching is successful, it is determined whether the time difference between the peak values of the second symbol and the first symbol is correct (step S72), if so, the next symbol is sequentially matched (step S73), until all L symbols are successfully detected, it is not indicated that the detection of the prefix sync signal or the post sync signal is successful (step S74), and finally the start and end positions of the detected data can be obtained (step S75). The advantages of this amplification method are: each symbol in the prefix sync signal/postsync signal is selected from the same sequence set without additional definition of more sequences, without increasing the memory requirement on hardware, and in addition, the group support amount of the maximum simultaneous operation can be rapidly increased by connecting a plurality of symbols in series.

Taking the practical situation of the amplification method disclosed in this disclosure as an example, if the design method of embodiment 1 is used, the length of the prefix synchronization signal is 256 symbols, and the Zadoff-Chu sequence with the length of 64 is centrally configured in the frequency domain, at this time, 4 times of sub-sampling rate matching can be supported at most, and 64 groups can be supported at most to operate simultaneously, if it is desired to further extend to be able to support 1000 groups to operate simultaneously, the group support amount amplification method disclosed in this disclosure (embodiment 3) is used to concatenate the two prefix synchronization signals, and the Zadoff-Chu sequences of the two prefix synchronization signals can be the same or different, so that 64 groups can be supported at most²4096 groups operate simultaneously, and the maximum number of groups capable of operating simultaneously is greatly increased without changing the original prefix synchronization signal and additionally defining other sequences. At the receiving end, according to the detection process shown in fig. 8B, each time a sampling point is received, the second prefix sync signal is matched, and the first prefix sync signal is also matched for the received sampling delayed by 256 points.

In addition, if it is desired to use the software defined radio in a very low snr environment, the threshold used for the matching decision is relatively lowered, and a false alarm starts to occur, and the probability of the false alarm must be reduced as much as possible, and the present disclosure tests for two false alarm situations: (1) detecting packets of the same group, wherein the detection is successful but the initial position of the obtained user signal is wrong, (2) detecting packets of other groups, and the detection is successful and the packets are mistaken for the user signal of the group. Fig. 9A and 9B show false alarm rates in two cases, where only one 256-point symbol is used as a prefix sync signal without using the group support amount amplification method of the present disclosure, and where the group support amount amplification method of the present disclosure is used, the two 256-point symbols connected in series are used as the prefix sync signal, and the design of embodiment 1 is used in both cases, as can be seen from fig. 9A and 9B, the false alarm rate can be greatly reduced by using the group support amount amplification method of the present disclosure.

The above-described embodiments are merely illustrative of the principles, features and effects of the present disclosure, and are not intended to limit the scope of the disclosure, which can be modified and varied by those skilled in the art without departing from the spirit and scope of the present disclosure. Any equivalent changes and modifications made using the disclosure of the present disclosure are intended to be covered by the scope of the claims. Therefore, the protection scope of the present disclosure should be as set forth in the claims.