HE-LTF channel blind detection method, system and radio frequency measurement system

Abstract

The present invention discloses a HE‑LTF channel blind detection method, system and radio frequency measurement system, and belongs to the field of wireless communication technology. According to the starting position of HE‑LTF, the present invention calculates the correlation value of all possible received HE‑LTF time domain signal sequences and the local reference time domain signal sequence of HE‑LTF; finds the HE‑LTF time domain signal sequence corresponding to the maximum correlation value; converts the HE‑LTF time domain signal sequence to the frequency domain, and performs HE‑LTF channel estimation. The present invention eliminates the tediousness of successively parsing the information in the HE‑SIG‑A and HE‑SIG‑B channels, simplifies the measurement process, speeds up the measurement of the algorithm to a certain extent, and at the same time, reduces the configuration of a large number of parameters, and also reduces the influence of parameter misconfiguration on algorithm analysis, improves the robustness of the measurement, and improves the universality of the algorithm.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to a HE-LTF channel blind detection method and system. Background Art

[0002] IEEE802.11ax, commonly known as Wi-Fi 6, is an important advancement in wireless local area network (WLAN) technology, designed to improve spectrum efficiency and actual throughput in dense user environments. The goal of this standard is to increase the average user throughput by at least 4 times in high-density deployment scenarios. This standard is also called High Efficiency Wi-Fi.

[0003] 802.11ax introduces some key technical features such as OFDMA (Orthogonal Frequency Division Multiple Access), MIMO (Multiple Input Multiple Output), and multiple HE channels. Among them, OFDMA introduces HE-Multiple Users (HE-MU), which allows WLAN wireless access points to send or receive data simultaneously by allocating different subcarriers to multiple users in the same time segment, reducing the delay when multiple users compete for channel resources and improving spectrum utilization. The protocol also designs a new frame structure HE-MU for multi-user scenarios. Its frame structure is as follows: Figure 1 Compared with the HE-SU (HE-SingleUser) frame structure in the single-user scenario, the time length of the HE-SIG-B channel in the HE-MU frame structure will vary depending on the configuration.

[0004] The following table shows the names and abbreviations of the 802.11AX channels.

[0005] Table 1. Names and abbreviations of 802.11AX channels

[0006]

[0007] According to the 802.11 protocol, the following table lists the length and position of each channel of AxWIFI in HE-SU and HE-MU frame formats. It can be seen that in HE-SU mode, the position of HE-LTF is fixed, and its position deviates from the frame header by 32us. In HE-MU mode, due to the uncertain length of HE-SIG-B, the starting position of HE-MU is not fixed.

[0008] Table 2. Starting position and length of each channel in the frame structure of 802.11A XHE-SU and HE-MU

[0009]

[0010] The protocol specifies that the length of HE-SIG-B is a multiple of symbol. The length of each symbol is 4us. This multiple N must satisfy 1 .

[0011] For the frame structure of 802.11ax HE-MU, the general parsing steps are to first parse the information in RL-SIG and HE-SIG-A to obtain the number of symbols N of HE-SIG-B, thereby estimating the length of HE-SIG-B, and then deriving the location of HE-LTF and parsing the DATA channel. It is necessary to parse the information in the HE-SIG-A and HE-SIG-B channels in turn to find the location of HE-LTF and obtain the HE-LTF information and Data, which affects the decoding efficiency; on the other hand, if each channel needs to be correctly parsed, then the signal source and receiver need to be completely and correctly configured and parsed for all configuration items, resulting in a relatively high configuration complexity. If there is a slight mismatch in the parameters, HE_LTF and Data cannot be parsed. Summary of the invention

[0012] The present invention aims to solve the technical problems existing in the prior art and provides a HE-LTF channel blind detection method and system. According to the starting position of HE-LTF, the correlation values ​​of all possible received HE-LTF time domain signal sequences and the local reference time domain signal sequence of HE-LTF are calculated; the HE-LTF time domain signal sequence corresponding to the maximum correlation value is found; and HE-LTF channel estimation is performed. The present invention eliminates the tediousness of sequentially parsing the information in the HE-SIG-A and HE-SIG-B channels, simplifies the measurement process, speeds up the measurement of the algorithm to a certain extent, and at the same time, reduces the configuration of a large number of parameters, reduces the impact of incorrect parameter configuration on algorithm analysis, improves the robustness of the measurement, and improves the universality of the algorithm.

[0013] The present invention provides a HE-LTF channel blind detection method, comprising the following steps:

[0014] Determine the starting position of the frame where the HE-LTF is located;

[0015] Calculate the correlation values ​​of all possible received HE-LTF time domain signal sequences and the local reference time domain signal sequence of the HE-LTF;

[0016] Find the HE-LTF time domain signal sequence corresponding to the maximum correlation value;

[0017] The HE-LTF time domain signal sequence corresponding to the maximum correlation value is transferred to the frequency domain to obtain a HE-LTF frequency domain signal sequence, and the HE-LTF frequency domain signal sequence is used to perform HE-LTF channel estimation;

[0018] Determine whether the estimated HE-LTF channel meets the consistency requirements.

[0019] Preferably, determining the starting position of the frame where the HE-LTF is located specifically includes:

[0020] Detect the position of the WLAN frame header through the long training field and the short training field;

[0021] Perform clock synchronization estimation and compensation between the receiving end and the transmitting end, as well as frequency offset estimation and compensation.

[0022] Preferably, clock synchronization between the receiving end and the transmitting end is estimated and compensated based on the short training field L-STF and the long training field L-LTF.

[0023] Preferably, the frequency offset is estimated through the long training field L-LTF, and the frequency offset compensation is completed.

[0024] Preferably, calculating the correlation values ​​of all possible received HE-LTF time domain signal sequences and the local reference time domain signal sequence of the HE-LTF specifically includes:

[0025] After detecting the position of the WLAN frame header through the long training field L-LTF and the short training field L-STF, the earliest possible position t of HE-LTF is found according to the frame structure specified in the protocol. The received HE-LTF time domain signal sequence is ;

[0026] Obtain the local reference time domain signal sequence of HE-LTF according to the configuration parameter WLAN signal bandwidth ;

[0027] The following formula is used to calculate the HE-LTF time domain signal sequence received at time t and the next 4ns later: Local reference time domain signal sequence with HE-LTF The correlation value of And normalize it:

[0028]

[0029] The range of n is .

[0030] Preferably, find the normalized correlation value The n value corresponding to the maximum correlation value in is ,get Corresponding HE-LTF time domain signal sequence .

[0031] Preferably, the HE-LTF time domain signal sequence is converted to the frequency domain by the following method:

[0032] Selecting a HE-LTF time domain signal sequence containing part of the CP data according to the protocol;

[0033] Then the HE-LTF frequency domain signal sequence is obtained through FFT transformation. ,in, represents the subcarrier coefficient, , K is the total number of subcarriers.

[0034] Preferably, the obtained HE-LTF frequency domain signal sequence data Divide by the local reference frequency domain signal sequence , and obtain the frequency domain channel estimation of He-LTF , the formula is as follows: .

[0035] Preferably, the consistency is estimated by the variance or standard deviation of the channel estimate.

[0036] Preferably, the consistency is estimated by the variance or standard deviation of the channel amplitudes.

[0037] Preferably, the consistency is estimated by the variance or standard deviation of the channel phase.

[0038] The present invention also provides a HE-LTF channel blind detection system, comprising a processor, which executes the above-mentioned HE-LTF channel blind detection method.

[0039] The present invention also provides a radio frequency measurement system, including a receiving end and a transmitting end, which applies the above-mentioned HE-LTF channel blind detection method to perform channel measurement.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] 1. The present invention directly obtains the position of HE_LTF through a blind detection algorithm, thereby obtaining the data of HE-LTF and data data. The measurement system can directly skip each channel during the channel parsing process and directly parse the HE-LTF channel and the Data channel, thereby speeding up the measurement speed and simplifying the measurement process;

[0042] 2. The measurement system using the blind detection algorithm of the present invention can achieve correct analysis without configuring multiple input parameters, which reduces the configuration complexity and also improves the robustness of the decoding of the measuring instrument. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The frame structure of HE-SU and HE-MU frames defined for 802.11AX;

[0044] Figure 2 This is a flow chart of a HE-LTF channel blind detection method according to an embodiment of the present invention;

[0045] Figure 3 This is a flow chart of a HE-LTF channel blind detection method according to another embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The present invention provides a HE-LTF channel blind detection method, comprising the following steps:

[0048] Determine the starting position of the frame where the HE-LTF is located;

[0049] Calculate the correlation values ​​of all possible received HE-LTF time domain signal sequences and the local reference time domain signal sequence of the HE-LTF;

[0050] Find the HE-LTF time domain signal sequence corresponding to the maximum correlation value;

[0051] The HE-LTF time domain signal sequence corresponding to the maximum correlation value is transferred to the frequency domain to obtain a HE-LTF frequency domain signal sequence, and the HE-LTF frequency domain signal sequence is used to perform HE-LTF channel estimation;

[0052] Determine whether the estimated HE-LTF channel meets the consistency requirements.

[0053] According to some specific embodiments of the present invention, determining the starting position of the frame where the HE-LTF is located specifically includes:

[0054] The position of the WLAN frame header is detected through the long training field L-LTF and the short training field L-STF;

[0055] Perform clock synchronization estimation and compensation between the receiving end and the transmitting end, as well as frequency offset estimation and compensation.

[0056] According to some specific embodiments of the present invention, clock synchronization estimation and compensation of the receiving end and the transmitting end are performed based on the short training field L-STF and the long training field L-LTF.

[0057] According to some specific embodiments of the present invention, the frequency offset is estimated through the long training field L-LTF, and the frequency offset compensation is completed.

[0058] According to some specific embodiments of the present invention, calculating the correlation values ​​of all possible received HE-LTF time domain signal sequences and the local reference time domain signal sequence of the HE-LTF specifically includes:

[0059] After detecting the position of the WLAN frame header through the long training field L-LTF and the short training field L-STF, the earliest possible position t of HE-LTF is found according to the frame structure specified in the protocol. The received HE-LTF time domain signal sequence is ;

[0060] Obtain the local reference time domain signal sequence of HE-LTF according to the configuration parameter WLAN signal bandwidth ;

[0061] The following formula is used to calculate the HE-LTF time domain signal sequence received at time t and the next 4ns later: Local reference time domain signal sequence with HE-LTF The correlation value of And normalize it:

[0062]

[0063] The range of n is .

[0064] According to some specific embodiments of the present invention, the normalized correlation value is found The n value corresponding to the maximum correlation value in is ,get Corresponding HE-LTF time domain signal sequence .

[0065] According to some specific embodiments of the present invention, the HE-LTF time domain signal sequence is converted to the frequency domain using the following method:

[0066] Selecting a HE-LTF time domain signal sequence containing part of the CP data according to the protocol;

[0067] Then the HE-LTF frequency domain signal sequence is obtained through FFT transformation. ,in, represents the subcarrier coefficient, , K is the total number of subcarriers.

[0068] According to some specific embodiments of the present invention, the obtained HE-LTF frequency domain signal sequence data Divide by the local reference frequency domain signal sequence , and obtain the frequency domain channel estimation of He-LTF , the formula is as follows: .

[0069] According to certain specific embodiments of the present invention, error judgment of channel estimation is performed to determine whether the estimated HE-LTF channel meets the consistency requirements, and whether the HE-LTF channel is accurately found is determined based on the consistency.

[0070] According to some specific embodiments of the present invention, the consistency is estimated by the variance or standard deviation of the channel estimation.

[0071] According to some specific embodiments of the present invention, the consistency is estimated by the variance or standard deviation of the channel amplitude.

[0072] According to some specific embodiments of the present invention, the consistency is estimated by the variance or standard deviation of the channel phase.

[0073] The present invention also provides a HE-LTF channel blind detection system, comprising a processor, which executes the above-mentioned HE-LTF channel blind detection method.

[0074] The present invention also provides a radio frequency measurement system, including a receiving end and a transmitting end, which applies the above-mentioned HE-LTF channel blind detection method to perform channel measurement.

[0075] Example 1

[0076] like Figure 2 As shown, the present invention provides a HE-LTF channel blind detection method, comprising the following steps:

[0077] Determine the starting position of the frame where the HE-LTF is located;

[0078] Calculate the correlation values ​​of all possible received HE-LTF time domain signal sequences and the local reference time domain signal sequence of the HE-LTF;

[0079] Find the HE-LTF time domain signal sequence corresponding to the maximum correlation value;

[0080] The HE-LTF time domain signal sequence corresponding to the maximum correlation value is transferred to the frequency domain to obtain a HE-LTF frequency domain signal sequence, and the HE-LTF frequency domain signal sequence is used to perform HE-LTF channel estimation;

[0081] Determine whether the estimated HE-LTF channel meets the consistency requirements.

[0082] Example 2

[0083] The present invention provides a HE-LTF channel blind detection method, comprising the following steps:

[0084] The position of the WLAN frame header is detected through the long training field L-LTF and the short training field L-STF, the starting position of the frame where the HE-LTF is located is determined, and the clock synchronization estimation and compensation of the receiving end and the transmitting end, as well as the frequency deviation estimation and compensation are performed. Among them, the clock synchronization estimation and compensation of the receiving end and the transmitting end are performed based on the short training field L-STF and the long training field L-LTF. The frequency deviation is estimated through the long training field L-LTF, and the frequency deviation compensation is completed.

[0085] Calculate the correlation values ​​of all possible received HE-LTF time domain signal sequences and the local reference time domain signal sequence of the HE-LTF;

[0086] Find the HE-LTF time domain signal sequence corresponding to the maximum correlation value;

[0087] The HE-LTF time domain signal sequence corresponding to the maximum correlation value is transferred to the frequency domain to obtain a HE-LTF frequency domain signal sequence, and the HE-LTF frequency domain signal sequence is used to perform HE-LTF channel estimation;

[0088] Determine whether the estimated HE-LTF channel meets the consistency requirements.

[0089] Calculating the correlation values ​​of all possible received HE-LTF time domain signal sequences and the local reference time domain signal sequence of the HE-LTF specifically includes:

[0090] After detecting the position of the WLAN frame header through the long training field L-LTF and the short training field L-STF, the earliest possible position t of HE-LTF is found according to the frame structure specified in the protocol. The received HE-LTF time domain signal sequence is ;

[0091] Obtain the local reference time domain signal sequence of HE-LTF according to the configuration parameter WLAN signal bandwidth ;

[0092] The following formula is used to calculate the HE-LTF time domain signal sequence received at time t and the next 4ns later: Local reference time domain signal sequence with HE-LTF The correlation value of And normalize it:

[0093]

[0094] The range of n is .

[0095] Find the normalized correlation value The n value corresponding to the maximum correlation value in is ,get Corresponding HE-LTF time domain signal sequence ,Will The corresponding HE-LTF time domain signal sequence is converted into the frequency domain to obtain the HE-LTF frequency domain signal sequence, and the HE-LTF frequency domain signal sequence is used to perform HE-LTF channel estimation.

[0096] In this embodiment, the HE-LTF time domain signal sequence is converted to the frequency domain using the following method:

[0097] Selecting a HE-LTF time domain signal sequence containing part of the CP data according to the protocol;

[0098] Then the HE-LTF frequency domain signal sequence is obtained through FFT transformation. ,in, represents the subcarrier coefficient, , K is the total number of subcarriers.

[0099] The obtained HE-LTF frequency domain signal sequence data Divide by the local reference frequency domain signal sequence , and obtain the frequency domain channel estimation of He-LTF , the formula is as follows: .

[0100] Finally, the error judgment of the channel estimation is performed to determine whether the estimated HE-LTF channel meets the consistency requirements, and whether the HE-LTF channel is accurately found based on the consistency.

[0101] In this embodiment, the consistency is estimated by the variance or standard deviation of the channel estimation, and a threshold is set. If it is less than the threshold, it is determined that the HE-LTF channel is accurately found.

[0102] Example 3

[0103] The present invention provides a video measurement system, including a receiving end and a transmitting end, and applies the following steps to perform channel measurement, such as Figure 3 As shown:

[0104] Step 1: The receiving end detects the position of the WLAN frame header through the long training field (Long Training Field, LTF) and the short training field (Short Training Field, STF) to determine the starting position of the frame where the HE-LTF is located;

[0105] Step 2: The receiving end performs clock synchronization estimation and compensation based on the short training field L-STF and the long training field L-LTF. This step is to align the local clock of the receiving end with the clock of the transmitting end to ensure the accuracy of symbol timing.

[0106] Step 3: After clock synchronization is completed, the receiver estimates the frequency offset (FrequencyOffset) through L-LTF and completes frequency offset compensation. These three steps 1, 2, and 3 respectively complete the detection of the WLAN frame header, determine the starting position of the frame where the HE-LTF is located, clock synchronization compensation, and frequency offset estimation compensation. These steps are to obtain more accurate data and reduce the impact of time offset and frequency offset on HE-LTF blind detection;

[0107] Step 4: According to Table 2, find the earliest possible position t of HE-LTF, then the received HE-LTF time domain signal sequence is ,in Indicates the start time is A time domain signal sequence with a length of HE-LTF, and a local reference time domain signal sequence of HE-LTF is obtained according to the configuration parameter WLAN signal bandwidth , find the HE-LTF time domain signal sequence With the local reference time domain signal sequence The correlation value between And normalized, the formula is as follows:

[0108]

[0109] In order to obtain the data after 4ns and the reference time domain signal sequence The correlation value is assumed to be obtained after 4ns. , the above formula is further expanded to:

[0110]

[0111] The range of n is , keep looping through all the values ​​of n, if , then exit the loop and go directly to the next step 5;

[0112] Step 5: Get all the ,turn up The n corresponding to the maximum correlation value is , the formula is as follows:

[0113]

[0114] Then get Corresponding HE-LTF time domain data Go to step 6;

[0115] Step 6: Find the HE-LTF time domain signal sequence After that, the time domain signal sequence is converted to the frequency domain. In the process of converting the time domain, in order to reduce the interference between symbols, the received signal selected according to the protocol is the data containing part of the CP, and then the FFT transformation is performed and the HE-LTF frequency domain signal sequence is obtained. ,in, represents the subcarrier coefficient, , K is the total number of subcarriers, and then the obtained frequency domain signal sequence Divide by the local reference frequency domain signal sequence , we get the channel estimation of HE-LTF, the formula is as follows,

[0116]

[0117] in, represents the subcarrier coefficient, .

[0118] Step 7, estimate the standard deviation of the channel by the following To estimate consistency and determine whether the correct HE-LTF channel has been found:

[0119]

[0120] in, represents the mean of the channel;

[0121] In order to determine whether the HE-LTF channel is obtained accurately, a threshold is set ,if Confirm that the correct HE-LTF channel is found, here The default value is set to 0.1.

[0122] Since WLAN RF measurements are generally wired, there is no multipath effect, so the measured channel maintains good flatness over the entire bandwidth. At the same time, due to frequency and time offset compensation, the channel phase is basically consistent over the entire bandwidth. This means It remains basically consistent across the entire bandwidth, so consistency estimation can be used to determine whether the correct HE-LTF channel has been found.

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A HE-LTF channel blind detection method, characterized in that: The steps include: Determine the starting position of the frame where the HE-LTF is located; Calculate a correlation value between the received HE-LTF time domain signal sequence and the local reference time domain signal sequence of the HE-LTF; Find the HE-LTF time domain signal sequence corresponding to the maximum correlation value; The HE-LTF time domain signal sequence corresponding to the maximum correlation value is transferred to the frequency domain to obtain the HE-LTF frequency domain signal sequence , divided by the local reference frequency domain signal sequence , get the channel estimate of HE-LTF, ,in, represents the subcarrier coefficient, K is the total number of subcarriers, ; The consistency is estimated through channel estimation, and a threshold is set. If the value is less than the threshold, it is determined that the HE-LTF channel is accurately found.

2. The HE-LTF channel blind detection method according to claim 1, characterized in that Determining the starting position of the frame where the HE-LTF is located specifically includes: The position of the WLAN frame header is detected through the long training field L-LTF and the short training field L-STF; Perform clock synchronization estimation and compensation between the receiving end and the transmitting end, as well as frequency offset estimation and compensation, to determine the starting position of the frame where the HE-LTF is located.

3. The HE-LTF channel blind detection method according to claim 2, characterized in that Calculating the correlation value between the received HE-LTF time domain signal sequence and the local reference time domain signal sequence of the HE-LTF specifically includes: After detecting the position of the WLAN frame header through the long training field L-LTF and the short training field L-STF, the earliest position t of the HE-LTF is found according to the frame structure specified by the protocol. The received HE-LTF time domain signal sequence is ; Obtain the local reference time domain signal sequence of HE-LTF according to the configuration parameter WLAN signal bandwidth ; The following formula is used to calculate the HE-LTF time domain signal sequence received 4ns after time t: Local reference time domain signal sequence with HE-LTF The correlation value of And normalize it: The range of n is .

4. The HE-LTF channel blind detection method according to claim 3, characterized in that Find the normalized correlation value The n value corresponding to the maximum correlation value in is ,get Corresponding HE-LTF time domain signal sequence .

5. The HE-LTF channel blind detection method according to any one of claims 1 to 4, characterized in that: The variance or standard deviation of the channel estimation is calculated, and the variance or standard deviation of the channel estimation is compared with the set threshold. If it is less than the threshold, the estimated HE-LTF channel meets the consistency requirement, and it is determined that the HE-LTF channel is accurately found.

6. A HE-LTF channel blind detection system, characterized in that: Includes a processor, which executes the HE-LTF channel blind detection method described in any one of claims 1-5.

7. A radio frequency measurement system, characterized in that: It includes a receiving end and a transmitting end, and applies the HE-LTF channel blind detection method described in any one of claims 1 to 5 to perform channel measurement.

Images