A method and device for selecting codebook for NR system

Abstract

The present invention relates to the field of computer communication, and in particular to a method and device for selecting a codebook for an NR system, comprising sending a channel sounding reference signal SRS, performing channel estimation on the signal, downsampling the channel estimation result by N times according to the channel condition, setting the PMI traversal range of the downsampled channel estimation value to the PMI of all layers in the port, multiplying the precoding matrix respectively, calculating the equivalent MI value, mapping the MI value to obtain the equivalent CQI and MCS, obtaining the tbsize from the corresponding layer, taking the layer, MCS and PMI corresponding to the largest tbsize as the result of this codebook selection, and recording the corresponding CQI1, layer1, PMI1 information until the next codebook selection cycle M. The present invention avoids a large amount of calculation and improves the efficiency of PMI search. For the case of 4 ports and 4 layers, the complexity can be reduced to 5 / 62N times at most.

Description

Technical Field

[0001] The present invention relates to the field of computer communication technology, and in particular to a method and device for selecting a codebook for an NR system. Background Art

[0002] In the NR system, the uplink shared channel PUSCH supports multi-codeword multi-layer transmission. The corresponding protocol defines multiple ports and precoding codebooks (PMI) for multiple layers. 2 antenna ports include 1layer / 2layer, a total of 9 codebooks (including coherent / partially coherent / incoherent codebooks), and 4 antenna ports include 1layer / 2layer / 3layer / 4layer, a total of 62 codebooks. The appropriate codebook selection has an important impact on the performance of PUSCH.

[0003] In the prior art, codebook transmission first sends a channel sounding reference signal SRS for channel estimation, then multiplies the channel estimation result by the precoding matrix, calculates the equivalent signal-to-noise ratio (SNR) after equalization, traverses all codebooks, and selects the codebook corresponding to the maximum equivalent signal-to-noise ratio as the optimal codebook. When the number of codebooks is large, this method will greatly increase the amount of calculation. Therefore, it is very important to select the codebook while ensuring good PUSCH reception performance. Summary of the invention

[0004] The object of the present invention is to provide a method and device for selecting a codebook for an NR system to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for selecting a codebook for an NR system comprises the following steps:

[0007] S101, setting the SRS codebook selection period to M;

[0008] S102, sending a channel sounding reference signal SRS and performing channel estimation;

[0009] S103, downsampling the channel estimation result by N times according to the channel condition;

[0010] S104, estimating the channel value after downsampling;

[0011] S105, set pmi, multiply by the precoding matrix respectively, calculate equivalent CQI, and obtain tbsize;

[0012] S106, taking the pmi corresponding to the largest tbsize as the result of this codebook selection, and recording the corresponding pmi1 information;

[0013] S107: Repeat steps S101 to S104, then multiply by the pmi1 matrix, calculate the equivalent CQI2, and select and set the pmi traversal range according to the difference between CQI2 and CQI1 and the threshold K, and filter out the pmi matrix;

[0014] S108, calculating the equivalent CQI according to the screened PMI matrix, and obtaining tbsize from the corresponding layer;

[0015] S109, taking the pmi corresponding to the largest tbsize as the result of this codebook selection, and recording and updating the corresponding pmi1 information;

[0016] S110, repeat the process from step S107 to step S109 until the next codebook selection cycle M.

[0017] Further, the step S105: sets the PMI traversal range to the PMI of all layers in the port, multiplies them by the precoding matrix respectively, calculates the equivalent MI value, maps the MI value to obtain the equivalent CQI and MCS, and obtains the tbsize from the corresponding layer.

[0018] Furthermore, the step S106: taking the layer, mcs and pmi corresponding to the largest tbsize as the result of this codebook selection, and recording the corresponding CQI1, layer1, pmi1 information.

[0019] Furthermore, the step S107: multiplying the downsampled channel estimation value by the previous pmi1 matrix to calculate an equivalent MI value, mapping the MI value to obtain an equivalent CQI2, and calculating a CQI2-CQI1 difference.

[0020] Further, the step S107: if the CQI difference is less than K, the pmi traversal range is set to all pmi matrices in the current layer; if the CQI difference is greater than K, the pmi traversal range is set to all pmi matrices in the current layer and adjacent layers, where layer is layer2=layer1+sign(CQI2-CQI1).

[0021] Further, the step S108: according to the screened pmi matrix, multiply the downsampled SRS channel estimation value respectively, calculate the equivalent MI value, obtain the equivalent CQI and mcs by the MI value mapping, and obtain tbsize by the corresponding layer.

[0022] Furthermore, the step S109: taking the layer, mcs and pmi corresponding to the largest tbsize as the result of this codebook selection, and recording and updating the corresponding CQI1, layer1, pmi1 information.

[0023] To achieve the above object, the present invention also provides the following technical solutions:

[0024] An NR system codebook selection device 110 includes:

[0025] A setting unit 111 is used to set the SRS codebook selection period to M;

[0026] The channel estimation unit 112 is used to send a channel sounding reference signal SRS and perform channel estimation;

[0027] A sampling unit 113, configured to downsample the channel estimation result by a factor of N according to the channel condition;

[0028] An estimation unit 114, configured to estimate the channel value after downsampling;

[0029] The pmi setting unit 115 is used to set the pmi, multiply the precoding matrix, calculate the equivalent CQI, obtain the tbsize, and calculate the equivalent CQI2, and select the pmi traversal range and filter out the pmi matrix according to the difference between CQI2 and CQI1 and the threshold K;

[0030] The calculation unit 116 is used to calculate the equivalent CQI according to the screened PMI matrix, and obtain tbsize from the corresponding layer;

[0031] The codebook screening unit 117 is used to take the pmi corresponding to the largest tbsize as the result of this codebook selection, and record the corresponding pmi1 information, and take the pmi corresponding to the largest tbsize as the result of this codebook selection, and record and update the corresponding pmi1 information;

[0032] The codebook determining unit 118 is configured to determine a codebook.

[0033] To achieve the above object, the present invention also provides the following technical solutions:

[0034] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of any one of the above methods when executing the computer program.

[0035] To achieve the above object, the present invention also provides the following technical solutions:

[0036] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of any one of the methods described above.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. According to the channel conditions, the SRS channel estimation result is downsampled by N times to reduce the computational complexity.

[0039] 2. In the search for PMI, the channel quality CQI is taken into account. When the channel quality changes slowly (the CQI difference is less than the threshold K), the PMI matrix is ​​searched within the current layer range, otherwise the PMI matrix is ​​searched within the current and adjacent layer ranges to avoid a large amount of calculation and improve the efficiency of PMI search. For the case of 4 ports and 4 layers, the complexity can be reduced to 5 / 62N times at most. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram of the steps of a method for selecting a codebook for an NR system provided by the present invention.

[0041] Figure 2 A flowchart of a method for selecting a codebook for an NR system provided by the present invention.

[0042] Figure 3 A block diagram of a device for selecting a codebook for an NR system provided by the present invention.

[0043] Figure 4 This is a diagram of the internal structure of the computer device provided by the present invention. DETAILED DESCRIPTION

[0044] 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. Obviously, 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.

[0045] See also Figure 1-4 , the present invention provides a technical solution:

[0046] A method and device for selecting a codebook for an NR system, which can reduce the complexity of codebook selection while ensuring PUSCH reception performance.

[0047] When scheduling codebook transmission, the specific implementation process and method of this solution are as follows:

[0048] Set the SRS codebook selection period to M, and the initial codebook selection process is:

[0049] 1. Send a channel sounding reference signal SRS to perform channel estimation

[0050] 2. According to the channel conditions, the channel estimation results are downsampled by N times

[0051] 3. For the downsampled channel estimation value, set the PMI traversal range to the PMI of all layers in the port, multiply them by the precoding matrix, calculate the equivalent MI value, and map the MI value to obtain the equivalent channel quality indication (CQI) and modulation and coding scheme (MCS). From the corresponding layer, obtain the code block size (tbsize), where in the codebook selection period, this range is: the first time is the PMI of all layers in the port, and then the PMI of all layers or adjacent layers of the current port is selected based on the comparison of the difference calculated by CQI;

[0052] 4. Take the layer, MCS and pmi corresponding to the largest tbsize as the result of this codebook selection, and record the corresponding CQI1, layer1, pmi1 information

[0053] The next codebook selection process is:

[0054] 5. Send a channel sounding reference signal SRS to perform channel estimation

[0055] 6. According to the channel conditions, the channel estimation results are downsampled by N times

[0056] 7. Multiply the downsampled channel estimate by the previous pmi1 matrix to calculate the equivalent MI value, map the MI value to get the equivalent CQI2, and calculate the CQI2-CQI1 difference

[0057] 8. If the CQI difference is less than K, where k refers to the range of the CQI index difference, then the PMI traversal range is set to all PMI matrices in the current layer.

[0058] 9. If the CQI difference is greater than K, set the PMI traversal range to all PMI matrices in the current layer and adjacent layers (layer2 = layer1 + sign (CQI2-CQI1))

[0059] 10. For the pmi matrix selected in the previous step, multiply the downsampled SRS channel estimation value respectively, calculate the equivalent MI value, map the MI value to obtain the equivalent CQI and MCS, and obtain the tbsize from the corresponding layer. Take the layer, MCS and pmi corresponding to the largest tbsize as the result of this codebook selection, and record and update the corresponding CQI1, layer1, pmi1 and other information

[0060] Repeat the above steps 5-10 until the next codebook selection cycle M, and repeat the steps 1-10.

[0061] The program flow chart is shown in Figure 3.

[0062] The device of the present invention mainly comprises the following units: a channel estimation unit, a codebook screening unit, a calculation unit and a codebook determination unit

[0063] Channel Estimation Unit

[0064] Channel estimation for the received sounding reference signal SRS

[0065] Screening code unit

[0066] Determine which codebooks can enter the next calculation unit according to the conditions

[0067] Computational Unit

[0068] 1. Calculate SNR through MMSE equalization;

[0069] Assume the precoding matrix is ​​P, the channel matrix obtained by channel estimation is H and the noise power σ 2 , () -1 To find the inverse of a matrix, () H is the complex conjugate transposed matrix

[0070] Calculate the MMSE matrix W:

[0071]

[0072] Calculating Equivalent Noise Power

[0073]

[0074] Calculate the signal power S, where diag is the diagonal element:

[0075] S=diag(WH)

[0076] Calculate the equivalent SNR:

[0077]

[0078] 2. Calculate MI by SNR

[0079] For different modulation modes, the probability density function (PDF) under the log-likelihood ratio (LLR) obeys a mixed Gaussian distribution, where the mutual information is expressed as the J(·) function, x is the SNR, a i is the coefficient of the J(·) function, satisfying

[0080]

[0081]

[0082] For different modulation modes, m is the order, SNR is represented by γ, and the MI calculation function is represented by I m (γ)

[0083] The PDF of LLR for QPSK modulation is expressed as I2(γ)

[0084] The PDF of LLR for 16QAM modulation is expressed as I4(γ)

[0085] The PDF of LLR for 64QAM modulation is expressed as I6(γ)

[0086] The PDF of LLR for 256QAM modulation is expressed as I8(γ)

[0087] The MI fitting calculation is shown in Table 1:

[0088]

[0089] Table 1

[0090] When there are n subcarriers, first calculate the MI on each subcarrier and then calculate the average.

[0091] For MIMO channels, N t Transmitting antennas, N r receive antennas, calculate the average value M of Mi:

[0092]

[0093] Calculate the MI values ​​corresponding to the four modulation orders respectively each time;

[0094] Determine the codebook unit

[0095] The CQI-MI table MITh (as shown in Table 2 below), i.e., the MI threshold, is obtained through simulation. According to the calculated MI, the CQI with a high modulation order is selected first, and the CQI with a high modulation order is selected from high to low.

[0096] Right now:

[0097]

[0098]

[0099] Where Len is the length of the CQI table;

[0100] Start*_idx is the corresponding starting index under different modulation modes

[0101]

[0102] Table 2

[0103] Advantages of the invention

[0104] 1. According to the channel conditions, the SRS channel estimation result is downsampled by N times to reduce the computational complexity.

[0105] 2. In the search for PMI, the channel quality CQI is taken into account. When the channel quality changes slowly (the CQI difference is less than the threshold K), the PMI matrix is ​​searched within the current layer range, otherwise the PMI matrix is ​​searched within the current and adjacent layer ranges to avoid a large amount of calculation and improve the efficiency of PMI search. For the case of 4 ports and 4 layers, the complexity can be reduced to 5 / 62N times at most.

[0106] In the present invention, the computer device may include a memory, a storage controller, one or more (only one is shown in the figure) processors, etc., and each element is electrically connected directly or indirectly to realize data transmission or interaction. For example, these elements can be electrically connected through one or more communication buses or signal buses. The method for selecting the NR system codebook includes at least one software function module that can be stored in the memory in the form of software or firmware, such as a software function module or computer program included in the device for selecting the NR system codebook. The memory can store various software programs and modules, such as the program instructions / modules corresponding to the method and device for selecting the NR system codebook provided in the embodiment of the present application. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory, that is, implementing the parsing method in the embodiment of the present application.

[0107] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for selecting a codebook for an NR system, characterized in that: include: Step 1: Set the SRS codebook selection period to M; Step 2: Send a channel sounding reference signal SRS and perform channel estimation; Step 3: Downsample the channel estimation result by N times according to the channel conditions; Step 4: estimate the channel value after downsampling; Step 5: Set pmi, multiply by the precoding matrix, calculate the equivalent CQI, and get tbsize; Step 6: Take the layer, mcs and pmi corresponding to the largest tbsize as the result of this codebook selection, and record the corresponding CQI1, layer1, pmi1 information; Step 7: Repeat steps 2 to 4, then multiply with the pmi1 matrix to calculate the equivalent CQI2, and select the pmi traversal range according to the difference between CQI2 and CQI1 and the threshold K, and filter out the pmi matrix. If the CQI difference is less than K, set the pmi traversal range to all pmi matrices in the current layer. If the CQI difference is greater than K, set the pmi traversal range to all pmi matrices in the current layer and adjacent layers. Step 8: Calculate the equivalent CQI based on the selected PMI matrix, and get tbsize from the corresponding layer; Step 9: Take the pmi corresponding to the largest tbsize as the result of this codebook selection, and record and update the corresponding pmi1 information; Step 10: Repeat steps 7 to 9 until the next codebook selection cycle M.

2. The method for selecting a codebook for an NR system according to claim 1, wherein: Step 5: Set the PMI traversal range to the PMI of all layers in the port, multiply them by the precoding matrix respectively, calculate the equivalent MI value, map the MI value to obtain the equivalent CQI and MCS, and obtain the tbsize from the corresponding layer.

3. The method for selecting a codebook for an NR system according to claim 1, wherein: The step 7: multiply the downsampled channel estimation value by the previous pmi1 matrix to calculate the equivalent MI value, obtain the equivalent CQI2 by mapping the MI value, and calculate the CQI2-CQI1 difference.

4. The method for selecting a codebook for an NR system according to claim 1, wherein: The step 7: wherein layer is layer2=layer1+sign(CQI2-CQI1).

5. The method for selecting a codebook for an NR system according to claim 1, wherein: The step 8: according to the screened pmi matrix, multiply the downsampled SRS channel estimation value respectively, calculate the equivalent MI value, map the MI value to obtain the equivalent CQI and mcs, and obtain tbsize from the corresponding layer.

6. The method for selecting a codebook for an NR system according to claim 1, wherein: Step 9: taking the layer, mcs and pmi corresponding to the largest tbsize as the result of this codebook selection, and recording and updating the corresponding CQI1, layer1, pmi1 information.

7. A device for selecting a codebook for an NR system, characterized in that: include: A setting unit, used to set the SRS codebook selection period to M; A channel estimation unit, used to send a channel sounding reference signal SRS and perform channel estimation; A sampling unit, used to downsample the channel estimation result by a factor of N according to the channel condition; An estimation unit, used for estimating a downsampled channel value; A pmi setting unit is used to set pmi, multiply the precoding matrix respectively, calculate the equivalent CQI, and obtain tbsize, take the layer, MCS and pmi corresponding to the largest tbsize as the result of this codebook selection, and record the corresponding CQI1, layer1, pmi1 information, and repeatedly perform the above operations of the channel estimation unit, the sampling unit and the estimation unit, and then multiply it with pmi1 to calculate the equivalent CQI2, and select and set the pmi traversal range according to the difference between CQI2 and CQI1 and the threshold K, and filter out the pmi matrix. If the CQI difference is less than K, the pmi traversal range is set to all pmi matrices in the current layer. If the CQI difference is greater than K, the pmi traversal range is set to all pmi matrices in the current layer and the adjacent layer; The calculation unit is used to calculate the equivalent CQI according to the screened PMI matrix, and obtain the tbsize from the corresponding layer; The codebook screening unit is used to take the pmi corresponding to the largest tbsize as the result of this codebook selection and record the corresponding pmi1 information; The codebook determination unit is used to determine the codebook.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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