Method for improving blind detection performance of demodulation reference signal in a 5G-like system

Abstract

The application discloses a method for improving blind detection performance of a demodulation reference signal in a 5G-like system and relates to the field of wireless communication. The application firstly performs primary synchronization signal and secondary synchronization signal detection on a received wireless signal, takes out an undemodulated synchronization signal block signal from the received signal for blind detection of a demodulation reference signal sequence according to a detection result, judges whether the index of the current synchronization signal block signal is calculated, if yes, performs a subsequent demodulation process on the current synchronization signal block signal and the corresponding index value, otherwise, calculates the index value of the synchronization signal block signal and performs a subsequent demodulation process. The application is based on the characteristics of the synchronization signal block signal in the 5G-like system and the detection result of the primary synchronization signal, reduces the number of times of blind detection of the demodulation reference signal sequence during terminal access, compresses the demodulation time and improves the network access speed under the condition of ensuring the accuracy of blind detection.

Description

Technical Field

[0001] This invention relates to the field of wireless communication, specifically to a method for improving the blind detection performance of demodulation reference signals in a 5G-like system. Background Technology

[0002] 5G-like systems use a Broadcast Channel (BCH) to transmit Synchronization Broadcast Signals (SSBs) on the downlink for terminal access. The SSB contains the Primary Synchronization Signal (PSS), the Secondary Synchronization Signal (SSS), and the PBCH. The PBCH contains PBCH data and the Demodulation Reference Signal (DMRS).

[0003] The terminal first performs PSS detection to obtain the position and NID2 of each SSB signal in the received signal; then it performs SSS detection to obtain the NID1 of each SSB signal; next, it selects a specific SSB signal for DMRS sequence blind detection to obtain the index value n of that SSB signal, which is used for subsequent demodulation; finally, it demodulates the SSB signal. If demodulation is successful, a random access attempt is made; otherwise, another SSB signal is selected for DMRS sequence blind detection and demodulation again, until the first demodulation is successful or all received SSB signals fail to be demodulated. The process by which the terminal receives and demodulates SSB signals to obtain access information is called cell search.

[0004] A base station transmits N (N is a positive integer) Service Blocks (SSBs) within a time period (burst). These SSBs carry the same access information but have different index values. Since DMRS generation is related to the SSB indexes, the DMRS sequences of these SSBs are different. A terminal may receive one or more SSB signals at a time and needs to decode them one by one until it successfully obtains the access information carried by at least one SSB. Before successful decoding, each SSB decoding requires a blind DMRS sequence detection. This involves generating N local sequences based on the N possible SSB index values ​​and cross-correlating each sequence with the received sequence N times. The SSB index value corresponding to the local sequence with the largest correlation result is taken as the index value of that SSB signal. This process is time-consuming. Furthermore, the blind DMRS sequence detection method is typically sensitive to frequency offset; when the received signal has a frequency offset, the blind detection performance will significantly degrade. Summary of the Invention

[0005] In view of this, the present invention proposes a method for improving the blind detection performance of demodulation reference signals in 5G-like systems. Based on the characteristics of SSB signals and PSS detection results in 5G-like systems, this invention reduces the number of DMRS sequence blind detections during terminal access while ensuring blind detection accuracy, thereby compressing demodulation time and improving network access speed.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for improving the blind detection performance of demodulation reference signals in a 5G-like system includes the following steps:

[0008] Step 1: The transmitting end sends N synchronization signal block signals within one cycle. The total set of the starting positions of the N synchronization signal block signals is P = {P0, P1, ..., P...} N-1 The terminal receives k synchronization signal blocks out of N synchronization signal blocks, where 2 < k ≤ N;

[0009] Step 2: The terminal performs primary synchronization signal detection and secondary synchronization signal detection on the received k synchronization signal block signals to obtain the cell ID number of the k synchronization signal block signals. Choose any set of cell ID numbers from the offset starting position. Given M identical synchronization signal blocks, construct a starting position subset L. Sort the starting offset positions of the M synchronization signal blocks in descending order of signal power, and then add them sequentially to the starting position subset L, where L = {L0, L1, ..., L...}. M-1}, 2 < M ≤ K;

[0010] Step 3: Set a loop variable 'a' to indicate the index of elements in the subset L of the starting position. Let a = 0, and construct a blind detection result table T. The blind detection result table T is used to store the index values ​​of the synchronization signal blocks of the M synchronization signal blocks. Based on the common cell ID number of the M synchronization signal blocks Given a set of positive integers [0, N-1], generate N sets of local demodulation reference signal sequences r. b (m), b = 0, 1, 2, ..., N-1;

[0011] Step 4: Based on the starting position L a Extract the signal from the received signal that is related to L. a For the corresponding synchronization signal block signal, perform a Fast Fourier Transform on the extracted synchronization signal block signal to convert it to the frequency domain, and check if the index value of the current synchronization signal block signal exists in the blind detection result table T. If yes, proceed to step 10; otherwise, proceed to step 5.

[0012] Step 5: According to the position of the demodulation reference signal sequence specified in the protocol, extract the demodulation reference signal sequence x(a) at the terminal from the synchronization signal block signal after the Fast Fourier Transform;

[0013] Step 6: Perform cross-correlation between the N local demodulated reference signal sequences rb(m) and the received demodulated reference signal sequence x(a), and sort the N correlation results from largest to smallest to obtain {R0, R1, ..., R...} N-1};

[0014] Step 7: Based on the maximum correlation result R0 and N sets of local demodulated reference signal sequences r b The mapping relationship of (m), and N sets of local demodulation reference signal sequences r b The mapping relationship between (m) and the total set of starting positions P yields the index value of the current synchronization signal block signal. index value Save the results to the blind detection results table T, and calculate the mean R of the remaining relevant results. ave :

[0015]

[0016] Based on the mean R ave Calculate the threshold value th for the relevant results:

[0017] th = alpha * R ave

[0018] If R1 < th, then proceed to step 10; otherwise, proceed to step 8, where alpha is the threshold coefficient.

[0019] Step 8: Determine if a is equal to M-1. If yes, proceed to step 10; otherwise, proceed to step 9.

[0020] Step 9: In the starting position subset L, calculate the offset starting position difference D between the current synchronization signal block signal and the subsequent synchronization signal block signal. j :

[0021] D j =L a -L j

[0022] Where j = a+1, a+2, ..., M-1;

[0023] Calculate the index value of the current synchronization signal block signal in the total set of starting positions P. The difference D′ between the corresponding starting position and the starting position of the other synchronization signal blocks k :

[0024]

[0025] wherein k = 0, 1, ..., N-1 and

[0026] For a synchronization signal block signal whose offset start position in the start position subset L is L j , the index value of the synchronization signal block signal can be obtained is:

[0027]

[0028] Add into the blind detection result table T, and continue to perform step 10;

[0029] Step 10: Perform a subsequent signal demodulation process according to the current synchronization signal block signal and the corresponding If the decoding succeeds, the process ends; if the decoding fails and a < M-1, set a = a+1, continue to perform step 4; otherwise, the process ends.

[0030] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects compared with the background art:

[0031] 1. The present invention calculates the indexes of other SSB signals through inter-signal starting position information and DMRS sequence blind detection results optimized by a threshold, which can greatly reduce calculation time and free up time margin for other steps of demodulation; because the overall demodulation time is reduced, the network access speed after the terminal is powered on is also accelerated.

[0032] 2. The present invention calculates the indexes of other SSB signals through inter-signal starting position information and DMRS sequence blind detection results optimized by a threshold, so the accuracy is significantly improved, and the success rate of network access is also improved accordingly. Description of Drawings

[0033] Figure 1 is an operation flow chart of a method for improving blind detection performance of demodulation reference signals in a 5G-like system according to an embodiment of the present invention.

[0034] Figure 2 is a comparison diagram of DMRS blind detection performance of different schemes with / without frequency offset according to an embodiment of the present invention. Detailed Description of Embodiments

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] A method for improving blind detection performance of demodulation reference signals, as shown in Figure 1 , comprising the following steps:

[0037] Step 1: The transmitting end sends N synchronization signal block signals within one cycle. The total set of the starting positions of the N synchronization signal block signals is P = {P0, P1, ..., P...} N-1 The terminal receives k synchronization signal blocks out of N synchronization signal blocks, where 2 < k ≤ N;

[0038] Step 2: The terminal performs PSS and SSS detection on the received k synchronization signal block signals to obtain the cell ID number of the k synchronization signal block signals. Choose any set of cell ID numbers from the offset starting position. Given M identical synchronization signal blocks, construct a starting position subset L. Sort the starting offset positions of the M synchronization signal blocks in descending order of signal power, and then add them sequentially to the starting position subset L, where L = {L0, L1, ..., L...}. M-1}, 2 < M ≤ K;

[0039] Step 3: Set a loop variable 'a' to indicate the index of elements in the subset L of the starting position. Let a = 0, and construct a blind detection result table T. The blind detection result table T is used to store the index values ​​of the synchronization signal blocks of the M synchronization signal blocks. Based on the common cell ID number of the M synchronization signal blocks Given a set of positive integers [0, N-1], generate N sets of local demodulation reference signal sequences rb(m), where b = 0, 1, 2, ..., N-1;

[0040] Step 4: Based on the starting position L a Extract the signal from the received signal that is related to L. a For the corresponding synchronization signal block signal, perform a Fast Fourier Transform on the extracted synchronization signal block signal to convert it to the frequency domain, and check if the index value of the current synchronization signal block signal exists in the blind detection result table T. If yes, proceed to step 10; otherwise, proceed to step 5.

[0041] Step 5: According to the position of the demodulation reference signal sequence specified in the protocol, extract the demodulation reference signal sequence x(a) at the terminal from the synchronization signal block signal after the Fast Fourier Transform;

[0042] Step 6: Perform cross-correlation between the N local demodulated reference signal sequences rb(m) and the received demodulated reference signal sequence x(a), and sort the N correlation results from largest to smallest to obtain {R0, R1, ..., R...} N-1};

[0043] Step 7: Based on the maximum correlation result R0 and N sets of local demodulated reference signal sequences r b The mapping relationship of (m), and N sets of local demodulation reference signal sequences r bThe mapping relationship between (m) and the total set of starting positions P yields the index value of the current synchronization signal block signal. index value Save the results to the blind detection results table T, and calculate the mean R of the remaining relevant results. aye :

[0044]

[0045] Based on the mean R ave Calculate the threshold value th for the relevant results:

[0046] th = alpha * R ave

[0047] If R1 < th, then proceed to step 10; otherwise, proceed to step 8, where alpha is the threshold coefficient.

[0048] Specifically, the threshold coefficient alpha is the coefficient at which the demodulation performance of the synchronization signal block signal reaches the expected standard through multiple simulations.

[0049] Step 8: Determine if a is equal to M-1. If yes, proceed to step 10; otherwise, proceed to step 9.

[0050] Step 9: In the starting position subset L, calculate the offset starting position difference D between the current synchronization signal block signal and the subsequent synchronization signal block signal. j :

[0051] D j =L a -L j

[0052] Where j = a+1, a+2, ..., M-1;

[0053] Calculate the index value of the current synchronization signal block signal in the total set of starting positions P. The difference D′ between the corresponding starting position and the starting position of the other synchronization signal blocks k :

[0054]

[0055] Where k = 0, 1, ..., N-1 and

[0056] For the subset L of starting positions, the offset starting position is L j By obtaining the synchronization signal block signal, the index value of that synchronization signal block signal can be obtained. for:

[0057]

[0058] Will Add the results to the blind test result table T, and continue to step 10;

[0059] Step 10: Based on the current synchronization signal block signal and the corresponding synchronization signal block signal... The subsequent signal demodulation process is then performed. If decoding is successful, the process ends; if decoding fails and a < M-1, then a = a+1, and step 4 continues; otherwise, the process ends.

[0060] Specifically, such as Figure 2 The diagram shows a performance comparison between this embodiment and the original blind detection scheme for the demodulated reference signal when there is no frequency offset and when there is a 15kHz frequency offset, with a subcarrier spacing of 120kHz. It can be seen that when the false detection rate is 1%, this embodiment improves performance by 0.8dB compared to the original scheme when there is no frequency offset, and by 1.5dB when there is a frequency offset. Therefore, this embodiment can improve the accuracy of blind detection of the demodulated reference signal.

[0061] With a subcarrier spacing of 120kHz, the base station continuously transmits 16 synchronization signal blocks each time. The terminal performs blind demodulation reference signal detection on all received synchronization signal blocks (16 or fewer), repeating this process 1000 times. Under different signal-to-noise ratios, if this embodiment is used, the average number of blind demodulation reference signal sequence detection processes that can be skipped each time is shown in the table below:

[0062] -10.3 6.76 -10 7.97 -9.7 9.15 -9.4 10.30 -9.1 11.36

[0063] As can be seen from the table above, when the terminal is performing cell search, in the worst case, it needs to perform blind detection of the demodulation reference signal sequence for all received synchronization signal block signals. If this embodiment is adopted, the number of blind detections can be significantly reduced.

[0064] Therefore, based on the characteristics of the synchronization signal block signal and the detection results of the main synchronization signal in 5G-like systems, this method reduces the number of times the terminal performs blind detection of the demodulation reference signal sequence during access, compresses the demodulation time, and improves the network access speed while ensuring the accuracy of blind detection.

[0065] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the present invention as defined in the appended claims should be included within the protection scope of the present invention.

Claims

1. A method for improving the blind detection performance of demodulation reference signals in a 5G-like system, characterized in that, comprising the following steps: Step 1: The transmitting end sends N synchronization signal block signals within one cycle. The total set of the starting positions of the N synchronization signal block signals is P = {P0, P1, ..., P...} N-1 The terminal receives k synchronization signal blocks out of N synchronization signal blocks, where 2 < k ≤ N; Step 2: The terminal performs primary synchronization signal detection and secondary synchronization signal detection on the received k synchronization signal block signals to obtain the cell ID number of the k synchronization signal block signals. Choose any set of cell ID numbers from the offset starting position. Given M identical synchronization signal blocks, construct a starting position subset L. Sort the starting offset positions of the M synchronization signal blocks in descending order of signal power, and then add them sequentially to the starting position subset L, where L = {L0, L1, ..., L...}. M-1 }, 2 < M ≤ K; Step 3: Set a loop variable 'a' to indicate the index of elements in the subset L of the starting position. Let a = 0, and construct a blind detection result table T. The blind detection result table T is used to store the index values ​​of the synchronization signal blocks of the M synchronization signal blocks. 0≤a≤M-1; based on the common cell ID number of the M synchronization signal blocks. Given an integer set [0, N-1], generate N sets of local demodulation reference signal sequences r. b (m), b = 0, 1, 2, ..., N-1; Step 4: Based on the starting position L a Extract the signal from the received signal that is related to L. a For the corresponding synchronization signal block signal, perform a Fast Fourier Transform on the extracted synchronization signal block signal to convert it to the frequency domain, and check if the index value of the current synchronization signal block signal exists in the blind detection result table T. If yes, proceed to step 10; otherwise, proceed to step 5. Step 5: extracting, according to the position of the demodulation reference signal sequence specified by the protocol, the demodulation reference signal sequence x(a) at the terminal from the fast Fourier transformed synchronization signal block signal; Step 6: Demodulate N sets of local demodulation reference signal sequences r b (m) is cross-correlated with the demodulated reference signal sequence x(a) at the terminal, and the N correlation results are sorted from largest to smallest to obtain {R0, R1, ..., R N-1 }; Step 7: Based on the maximum correlation result R0 and N sets of local demodulated reference signal sequences r b The mapping relationship of (m), and N sets of local demodulation reference signal sequences r b The mapping relationship between (m) and the total set of starting positions P yields the index value of the current synchronization signal block signal. index value Save the results to the blind detection results table T, and calculate the mean R of the remaining relevant results. ave : Based on the mean R ave Calculate the threshold value th for the relevant results: th=alpha*R ave if R1 < th, performing step 10, otherwise performing step 8, wherein alpha is a threshold coefficient; Step 8: determining whether a is equal to M-1, if yes, performing step 10, otherwise performing step 9; Step 9: In the starting position subset L, calculate the offset starting position difference D between the current synchronization signal block signal and the subsequent synchronization signal block signal. j : D j =L a -L j wherein, j = a+1, a+2, …, M-1; Calculate the index value of the current synchronization signal block signal in the total set of starting positions P. The difference D' between the corresponding starting position and the starting position of the other synchronization signal blocks k : Where k = 0, 1, ..., N-1 and For the subset L of starting positions, the offset starting position is L j By obtaining the synchronization signal block signal, the index value of that synchronization signal block signal can be obtained. for: Will Add the results to the blind test result table T, and continue to step 10; Step 10: according to the current synchronization signal block signal and the corresponding synchronization signal block signal performing a subsequent signal demodulation process, ending the process if decoding succeeds; if decoding fails and a<M-1, setting a = a+1 and continuing to perform step 4, otherwise ending the process.

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