Method and system suitable for comprehensive tester to analyze Wi-Fi OFDMA multi-user performance

Abstract

The invention provides a method and a system suitable for an integrated tester to analyze Wi-Fi OFDMA multi-user performance, and the method comprises a Client field splitting step, a Client channel estimation step, a Client residual frequency offset estimation step, a Client equalization step, a Client pilot frequency tracking step, a Client demodulation step, a first judgment step, a Client result analysis step, a second judgment step and an integrated signal analysis step. By tracking and demodulating the pilot frequency of each OFDM symbol in each Client and splitting and analyzing the signal corresponding to each Client, after an integrated tester uses the method, the measurement requirement that the DUT sends the signal to a plurality of Clients through OFDMA (Orthogonal Frequency Division Multiple Access) can be met, various receiving indexes of each accessed Client and the overall receiving index of the DUT can be evaluated, and the overall performance of the DUT can be improved. And the signal analysis requirement of the integrated tester on the multi-user OFDMA access of the DUT equipment is met.

Description

Technical Field

[0001] This invention relates to a performance analysis technique for a comprehensive testing instrument, and more particularly to a method and system suitable for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument. Background Technology

[0002] In the 802.11 system, physical layer data transmission is based on PPDU (Physical Layer Protocol Data Unit), meaning that uplink and downlink user transmissions are conducted through data packets containing data information from multiple users. For the transmitter in an 802.11ax / be downlink OFDMA (Orthogonal Frequency-Division Multiple Access) system, after the Access Point (AP) has associated with multiple users, the AP simultaneously transmits signals to all users.

[0003] Consider a basic service group scenario in an 802.11ax-based wireless local area network (WLAN) consisting of one access point (AP) and K users. The total channel bandwidth B is divided into N RUs (Run-Active Units). To make scheduling multi-user transmissions more flexible, 802.11ax supports combinations of RUs of different sizes, such as... Figure 1 As shown, the horizontal axis represents the allocation of channel resources to users in terms of time, while the vertical axis represents the allocation of channel resources to users in terms of frequency band.

[0004] The comprehensive test instrument measures the signals transmitted by the AP. The general mode is to measure the entire bandwidth allocated to a single user. Starting with the 802.11 protocol, a multi-user OFDMA mode has evolved. When the comprehensive test instrument measures OFDMA multi-users, it needs to separate the radio frequency indicators of each user. During the analysis, some information is mixed together, and some signals are separate. Therefore, the comprehensive test instrument measurement mode that is applicable to single users is not applicable.

[0005] Figure 2 The 802.11ax and 802.11be frame formats support OFDMA transmission. When performing multi-user transmission, the area before the HE-STF / EHT-STF field is shared by multiple users and needs to be used to resolve and compensate for common frequency offset and common sampling offset. After the HE-STF / EHT-STF field, each user is independent in the frequency domain, and it is necessary to calculate and compensate for the independent frequency offset and sampling offset of each user. The phase tracking based on the pilot in the Data field also becomes different. The final measurement index needs to integrate the common and independent parts, which poses new challenges to the measurement of the comprehensive tester. Therefore, a method that can analyze OFDMA multi-user transmission is needed. Summary of the Invention

[0006] To address the problems in the prior art, this invention provides a method and system for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive test instrument. It can simultaneously measure various reception indicators sent by the DUT to multiple accessing Clients and the overall reception indicators of the DUT. For ease of description, this invention refers to the AP that sends information as the DUT and the user terminal that receives information as the Client.

[0007] This invention relates to a method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument, comprising the following steps: Client field splitting: Based on the information parsed from the SIG field, the fields of each Client are split to obtain the frequency band information of each Client, and an index is built for each Client. A Client is a user terminal that accesses the wireless access point (AP) network. Client channel estimation: Channel estimation is performed on each client in sequence; Client residual frequency offset estimation: used to calculate the residual frequency offset in the frequency band of each client; Client equalization: Compensate for the residual frequency offset of each client based on the residual frequency offset in its own frequency band; Client pilot tracking: Obtain the overall phase offset of all pilot subcarriers and the phase offset of all pilot subcarriers relative to the subcarrier number, perform phase tracking compensation, and then update the channel estimate for use in the next OFDM symbol; Client demodulation: Demapping is performed on the subcarrier constellation points that have completed phase tracking compensation to obtain the standard reference position of each subcarrier constellation point after demapping; First judgment step: Determine whether all OFDM symbols of the Client have been demapped. If not, return to the Client residual frequency offset estimation step for the next OFDM symbol. If yes, execute the Client result analysis step. Client Result Analysis: After traversing all OFDM symbols, calculate the signal reception performance of the client; The second judgment step: Determine whether the analysis of all Client results is complete. If not, return to execute the Client channel estimation step for the next Client. If yes, execute the comprehensive signal analysis step. Comprehensive signal analysis: Calculate the performance indicators of the entire received signal and analyze the overall performance of the received signal.

[0008] The present invention also provides a system for implementing the above-described method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive test instrument, comprising: Client field splitting module: Based on the information parsed from the SIG field, it splits the fields of each Client to obtain the frequency band information of each Client and creates an index for each Client. A Client is a terminal that accesses the wireless access point (AP) network. Client channel estimation module: used to perform channel estimation processing on each Client sequentially; Client Residual Frequency Offset Estimation Module: Used to calculate the residual frequency offset in the frequency band of each Client; Client equalization module: performs residual frequency offset compensation for each client based on the residual frequency offset in its own frequency band; Client pilot tracking module: used to obtain the overall phase offset of all pilot subcarriers and the phase offset of all pilot subcarriers relative to the subcarrier number, perform phase tracking compensation, and then update the channel estimate for use in the next OFDM symbol; Client demodulation module: used to demap the subcarrier constellation points that have completed phase tracking compensation, and obtain the standard reference position of each subcarrier constellation point after demapping; The first judgment step module is used to determine whether all OFDM symbols of the Client have been demapped; The Client Result Analysis Module is used to calculate the signal reception performance of the Client after traversing all OFDM symbols. The second judgment module is used to determine whether the analysis of all Client results has been completed. Integrated Signal Analysis Module: Used to calculate the performance indicators of the entire received signal and analyze the overall performance of the received signal.

[0009] Compared with the prior art, the beneficial effects of the present invention are: in the Wi-Fi communication systems 11ax and 11be based on OFDM technology, when the DUT device (Device Under Test) sends MU frames for multi-user OFDMA access, the present invention can simultaneously measure various reception indicators sent by the DUT to multiple accessing Clients and the overall reception indicators of the DUT. This invention uses pilot phase information to calculate and compensate for common phase noise, and uses inter-symbol iteration to calculate and compensate for carrier phase noise, thereby improving the accuracy of receiver performance analysis. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the RU combination partitioning for AP in multi-user transmission; Figure 2 A schematic diagram of the frame format supporting OFDMA transmission for 802.11 ax and 802.11 be; Figure 3 This is a flowchart of the test procedure for using a comprehensive test instrument to analyze 802.11 system signals. Figure 4 This is a flowchart of the method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive tester, according to the present invention. Detailed Implementation

[0011] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0012] The method of using a comprehensive test instrument to analyze 802.11 system (11a / g / n / ac / ah / ax / be) signals is as follows: Figure 3 As shown, this process applies to situations where all bandwidth resources are allocated to a single client, but it is not suitable for MU frames accessed by multiple users via OFDMA. This invention optimizes this process to simultaneously measure various reception metrics sent by the DUT to multiple accessing clients, as well as the overall reception metrics of the DUT.

[0013] like Figure 4 The present invention relates to a method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive test instrument. The analysis method before the SIG field is consistent with existing procedures and will not be repeated here. The focus is on explaining the main innovations of this invention. The method of this invention includes the following steps: Client field splitting: Based on the information parsed from the SIG field, the fields of each Client are split to obtain the frequency band information of each Client, and an index is built for each Client. A Client is a user terminal that accesses the wireless access point (AP) network. Client channel estimation: Channel estimation is performed on each client in sequence; Client residual frequency offset estimation: used to calculate the residual frequency offset in the frequency band of each client; Client equalization: Compensate for the residual frequency offset of each client based on the residual frequency offset in its own frequency band; Client pilot tracking: Obtain the overall phase offset of all pilot subcarriers and the phase offset of all pilot subcarriers relative to the subcarrier number, perform phase tracking compensation, and then update the channel estimate for use in the next OFDM symbol; Client demodulation: Demapping is performed on the subcarrier constellation points that have completed phase tracking compensation to obtain the standard reference position of each subcarrier constellation point after demapping; First judgment step: Determine whether all OFDM symbols of the Client have been demapped. If not, return to the Client residual frequency offset estimation step for the next OFDM symbol. If yes, execute the Client result analysis step. Client Result Analysis: After traversing all OFDM symbols, calculate the signal reception performance of the client; The second judgment step: Determine whether the analysis of all Client results is complete. If not, return to execute the Client channel estimation step for the next Client. If yes, execute the comprehensive signal analysis step. Comprehensive signal analysis: Calculate the performance indicators of the entire received signal and analyze the overall performance of the received signal.

[0014] The following detailed examples illustrate the processing procedures and algorithms involved in each step.

[0015] 1. Steps for splitting the Client field.

[0016] In this step, the frequency domain subcarrier information of each Client after splitting is as follows: The data frames (MU frames) from multiple clients are obtained. The total number of MU frame symbols analyzed is S, and the index is s. One Client, index subscript is , No. The number of subcarriers for each Client is The index subscript is The carrier number is , No. The number of pilot subcarriers per Client is The index subscript is The carrier number is , For Client sequence number, This is the subcarrier sequence number.

[0017] The frequency domain subcarrier representation of the MU frame is as follows Pilot subcarriers are represented as The subcarrier representation of the HE / EHT-STF field in the training sequence is as follows: The subcarrier representation of the HE / EHT-LTF field of the training sequence is as follows: The reference signal for the HE / EHT-STF field of the training sequence is represented as follows: The reference signal for the HE / EHT-LTF field of the training sequence is represented as follows: The Client index OFDM symbol index Subcarrier index , .

[0018] 2. Client channel estimation steps.

[0019] In this step, each client is analyzed individually until all clients have been tested. The specific processing procedure is as follows: Obtain the reference signal for the HE / EHT-STF field of the training sequence. and the reference signal of the HE / EHT-LTF field of the training sequence and the frequency domain subcarriers of the corresponding received training sequence HE / EHT-STF field. Frequency domain subcarriers of the HE / EHT-LTF field of the training sequence , Channel estimation based on HE / EHT STF field of training sequence for: , The channel estimation based on the HE / EHT-LTF field of the training sequence is as follows: , use This indicates the number of effective subcarriers in the HE / EHT STF field of the training sequence. This represents the number of effective subcarriers in the HE / EHT-LTF field of the training sequence, and the total number of effective subcarriers. The final channel estimation formula is as follows: .

[0020] In the total steps of Client residual frequency offset, The HE / EHT STF field and the HE / EHT-LTF field of the training sequence differ by one OFDM symbol, and the time interval of one OFDM symbol is... The residual frequency offset can be estimated from the channel variations between them, and the residual frequency offset can be calculated using the following formula. : .

[0021] 3. Client load balancing steps.

[0022] In this step, the residual frequency offset changes with the symbol sequence s. For OFDM symbols s=1, the channel state is... The channel states after the second one are as follows: , Residual frequency offset compensation is performed on the Client, and the compensated frequency domain subcarriers The calculation process is as follows: , Equalized frequency domain subcarrier information In other words, the recovered transmission information is calculated using the following formula: .

[0023] 4. Client pilot tracing and demodulation steps.

[0024] The specific processing procedure for this step is as follows: (1) Calculate the center carrier position of the Client. Equalized frequency domain information The included pilot portion is equivalently represented as follows: Based on the demodulation information, the pilot reference value is expressed as: The center carrier position of the Client is represented as , (2) Use This represents the overall phase shift of all pilot subcarriers. The phase offset of all pilot subcarriers with corresponding subcarrier numbers is calculated as follows: , (3) Phase tracking compensation and updating channel estimates, Frequency domain information compensated after phase tracking for: , The updated channel estimate is used for the next OFDM symbol. for: ,

[0025] (4) Demapping, Based on the modulation information of the Client parsed from the SIG field, the constellation diagram of the corresponding modulation scheme is obtained. The frequency domain information is represented as a constellation point pattern (frequency domain information is imaginary; the actual positions of the I and Q paths are constellation points, and multiple possible standard reference positions constitute the constellation diagram). The constellation point demapping method is to find the standard reference position with the smallest Euclidean distance between the constellation point and the standard reference position in the constellation diagram. After demapping, the frequency domain information... The obtained reference position is denoted as .

[0026] 5. Client Result Analysis Steps.

[0027] In this step, the signal reception performance evaluation metrics for the Client include Error Vector Magnitude (EVM), final frequency offset, and / or phase difference between OFDM symbols. The formula for calculating the magnitude of the difference vector is: , Final frequency offset The calculation formula is: , The sampling bias is applied to the data after CFO compensation, and the phase difference between OFDM symbols The calculation formula is: , in, This refers to the frequency offset and its compensation amount across the entire bandwidth.

[0028] 6. Comprehensive signal analysis steps.

[0029] In this step, the performance indicators include overall signal reception quality, overall final frequency offset, overall final sampling offset, and the client's power and / or power amplification factor. Among these, overall signal reception quality... The calculation formula is: , Final frequency offset The calculation formula is: , Final sampling bias The calculation formula is: , The total power of all clients is obtained using the received signal voltage value. Calculate the power of each client. The calculation process is as follows: , Client power amplification factor The calculation formula is: , in, For the first One Client The sum of the channel estimation subcarrier powers, For the first One Client The channel estimation of the average power of subcarriers, Estimate the sum of subcarrier power for all Client channels. Estimate the average power of subcarriers for all Client channels.

[0030] Corresponding to the above method, the system applicable to the analysis of Wi-Fi OFDMA multi-user performance using a comprehensive testing instrument includes: Client field splitting module: Based on the information parsed from the SIG field, it splits the fields of each Client to obtain the frequency band information of each Client and creates an index for each Client. A Client is a terminal that accesses the wireless access point (AP) network. Client channel estimation module: used to perform channel estimation processing on each Client sequentially; Client Residual Frequency Offset Estimation Module: Used to calculate the residual frequency offset in the frequency band of each Client; Client equalization module: performs residual frequency offset compensation for each client based on the residual frequency offset in its own frequency band; Client pilot tracking module: used to obtain the overall phase offset of all pilot subcarriers and the phase offset of all pilot subcarriers relative to the subcarrier number, perform phase tracking compensation, and then update the channel estimate for use in the next OFDM symbol; Client demodulation module: used to demap the subcarrier constellation points that have completed phase tracking compensation, and obtain the standard reference position of each subcarrier constellation point after demapping; The first judgment step module is used to determine whether all OFDM symbols of the Client have been demapped; The Client Result Analysis Module is used to calculate the signal reception performance of the Client after traversing all OFDM symbols. The second judgment module is used to determine whether the analysis of all Client results has been completed. Integrated Signal Analysis Module: Used to calculate the performance indicators of the entire received signal and analyze the overall performance of the received signal.

[0031] As can be seen from the above, by using the method and system of the present invention, the comprehensive test instrument can simultaneously measure various reception indicators and the overall reception indicators of the DUT sent to multiple access clients. In addition, during the analysis process, pilot phase information is used to complete the calculation and compensation of common phase noise, and inter-symbol iteration is used to complete the calculation and compensation of carrier phase noise, thereby improving the accuracy of reception performance analysis. The present invention is particularly suitable for the comprehensive test instrument to analyze the downlink OFDMA multi-user reception performance and parameter indicators of the 802.11ax / be standard, and for using the comprehensive test instrument to analyze the downlink OFDMA multi-user performance and parameter indicators.

[0032] The specific embodiments described above are preferred embodiments of the present invention and are not intended to limit the specific scope of the present invention. The scope of the present invention includes, but is not limited to, these specific embodiments. All equivalent changes made in accordance with the present invention are within the protection scope of the present invention.

Claims

1. A method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument, characterized in that, Includes the following steps: Client field splitting: Based on the information parsed from the SIG field, the fields of each Client are split to obtain the frequency band information of each Client, and an index is built for each Client. A Client is a user terminal that accesses the wireless access point (AP) network. Client channel estimation: Channel estimation is performed on each client in sequence; Client residual frequency offset estimation: used to calculate the residual frequency offset in the frequency band of each client; Client equalization: Compensate for the residual frequency offset of each client based on the residual frequency offset in its own frequency band; Client pilot tracking: Obtain the overall phase offset of all pilot subcarriers and the phase offset of all pilot subcarriers relative to the subcarrier number, perform phase tracking compensation, and then update the channel estimate for use in the next OFDM symbol; Client demodulation: Demapping is performed on the subcarrier constellation points that have completed phase tracking compensation to obtain the standard reference position of each subcarrier constellation point after demapping; First judgment step: Determine whether all OFDM symbols of the Client have been demapped. If not, return to the Client residual frequency offset estimation step for the next OFDM symbol. If yes, execute the Client result analysis step. Client Result Analysis: After traversing all OFDM symbols, calculate the signal reception performance of the client; The second judgment step: Determine whether the analysis of all Client results is complete. If not, return to execute the Client channel estimation step for the next Client. If yes, execute the comprehensive signal analysis step. Comprehensive signal analysis: Calculate the performance indicators of the entire received signal and analyze the overall performance of the received signal.

2. The method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument according to claim 1, characterized in that: In the Client field splitting step, the frequency domain subcarriers of each Client after splitting are: The data frames (MU frames) from multiple clients are obtained. The total number of MU frame symbols analyzed is S, and the index is s. One Client, index subscript is , No. The number of subcarriers for each Client is The index subscript is The carrier number is , No. The number of pilot subcarriers per Client is The index subscript is The carrier number is , For Client sequence number, Subcarrier sequence number, The frequency domain subcarrier representation of the MU frame is as follows Pilot subcarriers are represented as The frequency domain subcarrier representation of the HE / EHT-STF field of the training sequence is as follows: The frequency domain subcarrier representation of the HE / EHT-LTF field of the training sequence is as follows: The reference signal for the HE / EHT-STF field of the training sequence is represented as follows: The reference signal for the HE / EHT-LTF field of the training sequence is represented as follows: The Client index OFDM symbol index Subcarrier index , .

3. The method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument according to claim 2, characterized in that: In the client channel estimation step, each client is analyzed individually until all clients have been detected. The specific processing procedure is as follows: Obtain the reference signal for the HE / EHT-STF field of the training sequence. and the reference signal of the HE / EHT-LTF field of the training sequence and the frequency domain subcarriers of the corresponding received training sequence HE / EHT-STF field. Frequency domain subcarriers of the HE / EHT-LTF field of the training sequence , Channel estimation based on HE / EHT STF field of training sequence for: , Channel estimation based on HE / EHT-LTF fields of training sequences for: , use This indicates the number of effective subcarriers in the HE / EHT STF field of the training sequence. This represents the number of effective subcarriers in the HE / EHT-LTF field of the training sequence, and the total number of effective subcarriers. The final channel estimation formula is as follows: 。 4. The method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument according to claim 3, characterized in that: In the total steps of Client residual frequency offset, The HE / EHT STF field and the HE / EHT-LTF field of the training sequence differ by one OFDM symbol, and the time interval of one OFDM symbol is... The residual frequency offset is estimated from the channel variations between them, and then calculated using the following formula. : 。 5. The method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument according to claim 4, characterized in that: In the client load balancing step The residual frequency offset varies with the symbol sequence s. For OFDM symbols s=1, the channel state is... The channel state after the second one is , Residual frequency offset compensation is performed on the Client, and the compensated frequency domain subcarrier information is obtained. The calculation process is as follows: , Equalized frequency domain subcarrier information In other words, the recovered transmission information is calculated using the following formula: 。 6. The method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument according to claim 4, characterized in that, The processing steps for client pilot tracing and demodulation are as follows: (1) Calculate the center carrier position of the Client. Equalized frequency domain information The included pilot portion is equivalently represented as follows: Based on the demodulation information, the pilot reference value is expressed as: The center carrier position of the Client is represented as , (2) Use This represents the overall phase shift of all pilot subcarriers. The phase offset of all pilot subcarriers with corresponding subcarrier numbers is calculated as follows: ， (3) Phase tracking compensation and updating channel estimates, Frequency domain information compensated after phase tracking for: , The updated channel estimate is used for the next OFDM symbol. for: , (4) Demapping, Based on the modulation information of the Client parsed from the SIG field, the constellation diagram of the corresponding modulation scheme is obtained. The frequency domain information is represented as a constellation point pattern. The constellation point demapping method is to find the standard reference position with the smallest Euclidean distance between the constellation point and the standard reference position in the constellation diagram. After demapping, the frequency domain information is... The obtained reference position is denoted as .

7. The method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument according to claim 6, characterized in that: In the client result analysis step, the client's signal reception performance evaluation indicators include Error Vector Magnitude (EVM) and Final Frequency Offset. and / or the phase difference between OFDM symbols, where, The formula for calculating the magnitude of the difference vector is: Final frequency offset The calculation formula is: , The sampling bias is applied to the CFO-compensated data, and the phase difference between OFDM symbols is... The calculation formula is: ,in, This refers to the frequency offset and its compensation amount across the entire bandwidth.

8. The method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument according to claim 7, characterized in that: In the comprehensive signal analysis step, the performance indicators include overall signal reception quality, overall final frequency offset, overall final sampling offset, and client power and / or power amplification factor. Among these, overall signal reception quality... The calculation formula is: , Final frequency offset The calculation formula is: , Final sampling bias The calculation formula is: , The total power of all clients is obtained using the received signal voltage value. Calculate the power of each client. The calculation process is as follows: ， Client power amplification factor The calculation formula is: , in, For the first One Client The sum of the channel estimation subcarrier powers, For the first One Client The channel estimation of the average power of subcarriers, Estimate the sum of subcarrier power for all Client channels. Estimate the average power of subcarriers for all Client channels.

9. A system for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument, for implementing the method for analyzing the multi-user performance of Wi-Fi OFDMA using a comprehensive testing instrument as described in any one of claims 1-8, characterized in that, include: Client field splitting module: Based on the information parsed from the SIG field, it splits the fields of each Client to obtain the frequency band information of each Client and creates an index for each Client. A Client is a terminal that accesses the wireless access point (AP) network. Client channel estimation module: used to perform channel estimation processing on each Client sequentially; Client Residual Frequency Offset Estimation Module: Used to calculate the residual frequency offset in the frequency band of each Client; Client equalization module: performs residual frequency offset compensation for each client based on the residual frequency offset in its own frequency band; Client pilot tracking module: used to obtain the overall phase offset of all pilot subcarriers and the phase offset of all pilot subcarriers relative to the subcarrier number, perform phase tracking compensation, and then update the channel estimate for use in the next OFDM symbol; Client demodulation module: used to demap the subcarrier constellation points that have completed phase tracking compensation, and obtain the standard reference position of each subcarrier constellation point after demapping; The first judgment step module is used to determine whether all OFDM symbols of the Client have been demapped; The Client Result Analysis Module is used to calculate the signal reception performance of the Client after traversing all OFDM symbols. The second judgment module is used to determine whether the analysis of all Client results has been completed. Integrated Signal Analysis Module: Used to calculate the performance indicators of the entire received signal and analyze the overall performance of the received signal.

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