Method for determining channel quality indicator (CQI) rollback amount and network equipment

Abstract

Provided are a method for determining a channel quality indicator (CQI) fallback amount and a network device, the method being applied to the network device, the method comprising: acquiring an uplink channel correlation matrix of an uplink channel between the network device and a terminal under the condition that a space division multiplexing fluxion number between the network device and the terminal changes; determining a characteristic index value of a downlink channel between the network equipment and the terminal according to the value of each element in the uplink channel correlation matrix; and according to the characteristic index value of the downlink channel, determining the CQI (Channel Quality Indicator) rollback amount of the downlink channel after the space division multiplexing fluxion number is changed. According to the scheme provided by the invention, the CQI rollback amount under the indoor distribution system can be determined.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a method and network device for determining a channel quality indicator CQI backoff amount. Background Art

[0002] The 5G New Radio (NR) system can support multi-stream transmission. The network equipment can select the corresponding number of streams for scheduling according to the channel environment of the terminal. This process can be called spatial division multiplexing stream number (rank) adaptation.

[0003] When the number of scheduled streams switches, the network device needs to estimate the Channel Quality Indicator (CQI) after the switch and determine the CQI fallback amount of the CQI after the switch relative to the CQI before the switch. Currently, the CQI fallback amount is mainly obtained by calibrating the transmitting and receiving antennas, and then obtaining the downlink channel information through the uplink channel estimation.

[0004] The above implementation scheme needs to be based on the premise of calibrating the transceiver antenna. However, for the indoor distributed system, the transceiver antenna is usually not calibrated, and the above scheme cannot be used to determine the CQI fallback amount. Therefore, it is necessary to provide a scheme for determining the CQI fallback amount in the indoor distributed system. Summary of the invention

[0005] The present application provides a method and network device for determining a channel quality index CQI backoff amount, so as to achieve determination of the CQI backoff amount in an indoor distributed system.

[0006] In a first aspect, the present application provides a method for determining a CQI backoff amount, which is applied to a network device, and the method includes:

[0007] When the number of space division multiplexing streams between the network device and the terminal changes, acquiring an uplink channel correlation matrix of an uplink channel between the network device and the terminal;

[0008] Determining a characteristic index value of a downlink channel between the network device and the terminal according to a value of each element in the uplink channel correlation matrix;

[0009] According to the characteristic indicator value of the downlink channel, a CQI fallback amount of the downlink channel is determined after the number of spatial division multiplexing streams changes.

[0010] In a possible implementation manner, determining the characteristic index value of the downlink channel between the network device and the terminal according to the value of each element in the uplink channel correlation matrix includes:

[0011] Determining a characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix, wherein the characteristic index value of the uplink channel is equal to the characteristic index value of the downlink channel;

[0012] The characteristic index value of the uplink channel is determined as the characteristic index value of the downlink channel.

[0013] In a possible implementation manner, determining the characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix includes:

[0014] Determining the sum of the complex amplitudes of a plurality of diagonal elements in the uplink channel correlation matrix as a first complex amplitude;

[0015] Determining the sum of the complex amplitudes of a plurality of off-diagonal elements in the uplink channel correlation matrix as a second complex amplitude;

[0016] The ratio of the second complex amplitude to the first complex amplitude is determined as the characteristic index value of the uplink channel.

[0017] In a possible implementation manner, determining the characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix includes:

[0018] Performing eigenvalue decomposition on the uplink channel correlation matrix to obtain multiple eigenvalues ​​of the uplink channel correlation matrix;

[0019] Determine a first eigenvalue having a maximum value and a second eigenvalue having a minimum value among the multiple eigenvalues;

[0020] The ratio of the second characteristic value to the first characteristic value is determined as the characteristic index value of the uplink channel.

[0021] In a possible implementation manner, determining, according to the characteristic indicator value of the downlink channel, the CQI fallback amount of the downlink channel after the number of spatial division multiplexing streams changes, includes:

[0022] Obtaining a mapping relationship between a characteristic indicator value range and a CQI fallback amount;

[0023] In the characteristic indicator value range, determining a target characteristic indicator value range to which the characteristic indicator value of the downlink channel belongs;

[0024] According to the mapping relationship, the CQI backoff amount corresponding to the target characteristic indicator value range is determined as the CQI backoff amount of the downlink channel.

[0025] In a possible implementation manner, the acquiring an uplink channel correlation matrix of an uplink channel between the network device and the terminal includes:

[0026] Performing channel estimation on the uplink channel to obtain an uplink channel estimation matrix;

[0027] The uplink channel correlation matrix is ​​acquired according to the uplink channel estimation matrix and the conjugate transposed matrix of the uplink channel estimation matrix.

[0028] In a second aspect, the present application provides a network device, including a memory, a transceiver, and a processor;

[0029] A memory for storing a computer program; a transceiver for transmitting and receiving data under the control of the processor; and a processor for reading the computer program in the memory and performing the following operations:

[0030] When the number of space division multiplexing streams between the network device and the terminal changes, acquiring an uplink channel correlation matrix of an uplink channel between the network device and the terminal;

[0031] Determining a characteristic index value of a downlink channel between the network device and the terminal according to a value of each element in the uplink channel correlation matrix;

[0032] According to the characteristic indicator value of the downlink channel, a CQI fallback amount of the downlink channel is determined after the number of spatial division multiplexing streams changes.

[0033] In a possible implementation manner, determining the characteristic index value of the downlink channel between the network device and the terminal according to the value of each element in the uplink channel correlation matrix includes:

[0034] Determining a characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix, wherein the characteristic index value of the uplink channel is equal to the characteristic index value of the downlink channel;

[0035] The characteristic index value of the uplink channel is determined as the characteristic index value of the downlink channel.

[0036] In a possible implementation manner, determining the characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix includes:

[0037] Determining the sum of the complex amplitudes of a plurality of diagonal elements in the uplink channel correlation matrix as a first complex amplitude;

[0038] Determining the sum of the complex amplitudes of a plurality of off-diagonal elements in the uplink channel correlation matrix as a second complex amplitude;

[0039] The ratio of the second complex amplitude to the first complex amplitude is determined as the characteristic index value of the uplink channel.

[0040] In a possible implementation manner, determining the characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix includes:

[0041] Performing eigenvalue decomposition on the uplink channel correlation matrix to obtain multiple eigenvalues ​​of the uplink channel correlation matrix;

[0042] Determine a first eigenvalue having a maximum value and a second eigenvalue having a minimum value among the multiple eigenvalues;

[0043] The ratio of the second characteristic value to the first characteristic value is determined as the characteristic index value of the uplink channel.

[0044] In a possible implementation manner, determining, according to the characteristic indicator value of the downlink channel, the CQI fallback amount of the downlink channel after the number of spatial division multiplexing streams changes, includes:

[0045] Obtaining a mapping relationship between a characteristic indicator value range and a CQI fallback amount;

[0046] In the characteristic indicator value range, determining a target characteristic indicator value range to which the characteristic indicator value of the downlink channel belongs;

[0047] According to the mapping relationship, the CQI backoff amount corresponding to the target characteristic indicator value range is determined as the CQI backoff amount of the downlink channel.

[0048] In a possible implementation manner, the acquiring an uplink channel correlation matrix of an uplink channel between the network device and the terminal includes:

[0049] Performing channel estimation on the uplink channel to obtain an uplink channel estimation matrix;

[0050] The uplink channel correlation matrix is ​​acquired according to the uplink channel estimation matrix and the conjugate transposed matrix of the uplink channel estimation matrix.

[0051] In a third aspect, the present application provides a device for determining a CQI backoff amount, which is applied to a network device, and the device includes:

[0052] An acquisition module, configured to acquire an uplink channel correlation matrix of an uplink channel between the network device and the terminal when the number of space division multiplexing streams between the network device and the terminal changes;

[0053] A processing module, used to determine a characteristic index value of a downlink channel between the network device and the terminal according to the value of each element in the uplink channel correlation matrix;

[0054] The determination module is used to determine, according to the characteristic indicator value of the downlink channel, the CQI fallback amount of the downlink channel after the number of spatial division multiplexing streams changes.

[0055] In a possible implementation manner, the processing module is specifically used to:

[0056] Determining a characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix, wherein the characteristic index value of the uplink channel is equal to the characteristic index value of the downlink channel;

[0057] The characteristic index value of the uplink channel is determined as the characteristic index value of the downlink channel.

[0058] In a possible implementation manner, the processing module is specifically used to:

[0059] Determining the sum of the complex amplitudes of a plurality of diagonal elements in the uplink channel correlation matrix as a first complex amplitude;

[0060] Determining the sum of the complex amplitudes of a plurality of off-diagonal elements in the uplink channel correlation matrix as a second complex amplitude;

[0061] The ratio of the second complex amplitude to the first complex amplitude is determined as the characteristic index value of the uplink channel.

[0062] In a possible implementation manner, the processing module is specifically used to:

[0063] Performing eigenvalue decomposition on the uplink channel correlation matrix to obtain multiple eigenvalues ​​of the uplink channel correlation matrix;

[0064] Determine a first eigenvalue having a maximum value and a second eigenvalue having a minimum value among the multiple eigenvalues;

[0065] The ratio of the second characteristic value to the first characteristic value is determined as the characteristic index value of the uplink channel.

[0066] In a possible implementation manner, the determining module is specifically configured to:

[0067] Obtaining a mapping relationship between a characteristic indicator value range and a CQI fallback amount;

[0068] In the characteristic indicator value range, determining a target characteristic indicator value range to which the characteristic indicator value of the downlink channel belongs;

[0069] According to the mapping relationship, the CQI backoff amount corresponding to the target characteristic indicator value range is determined as the CQI backoff amount of the downlink channel.

[0070] In a possible implementation manner, the acquisition module is specifically used to:

[0071] Performing channel estimation on the uplink channel to obtain an uplink channel estimation matrix;

[0072] The uplink channel correlation matrix is ​​acquired according to the uplink channel estimation matrix and the conjugate transposed matrix of the uplink channel estimation matrix.

[0073] In a fourth aspect, the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, wherein the computer program is used to enable a computer to execute the method for determining a CQI backoff amount as described in any one of the first aspects.

[0074] The method and network device for determining the CQI fallback amount provided in the present application obtain the uplink channel correlation matrix of the uplink channel between the network device and the terminal when the number of spatial division multiplexing streams between the network device and the terminal changes, and then determine the characteristic index value of the downlink channel between the network device and the terminal according to the value of each element in the uplink channel correlation matrix, so as to determine the CQI fallback amount of the downlink channel after the number of spatial division multiplexing streams changes according to the characteristic index value of the downlink channel. The solution provided in the present application estimates the multi-stream transmission capacity of the downlink channel by using uplink channel estimation, which solves the problem that the uplink channel estimation cannot be used directly to accurately reconstruct the CQI without performing channel calibration in the indoor scenario. It can adapt to the requirements of rank adaptive CQI reconstruction under different scenarios and antenna forms. The characteristic index value of the downlink channel is estimated by the uplink channel correlation matrix to determine the CQI fallback amount of the downlink channel, without the need to calibrate the transmitting and receiving antennas, and can be applied to the determination of the CQI fallback amount in the indoor system. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0076] Figure 1 A flowchart of a method for determining a CQI fallback amount provided in an embodiment of the present application;

[0077] Figure 2 A schematic diagram of the structure of a network device provided in an embodiment of the present application;

[0078] Figure 3 A schematic diagram of the structure of an apparatus for determining a CQI backoff amount provided in an embodiment of the present application. DETAILED DESCRIPTION

[0079] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0080] The 5G NR system can support multi-stream transmission. The network equipment can select the corresponding number of streams for scheduling according to the channel environment of the terminal. This process can be called rank adaptation.

[0081] When the number of scheduled streams switches, the network device needs to estimate the CQI after the switch and determine the CQI fallback amount of the CQI after the switch relative to the CQI before the switch, that is, rank adaptive CQI reconstruction.

[0082] At present, for large-scale antenna scenarios, the existing macro station rank adaptive CQI reconstruction schemes are divided into non-codebook schemes and codebook schemes. Among them, the non-codebook scheme mainly uses non-codebook shaping coefficients to calculate shaping gain, while the codebook scheme refers to falling back to a fixed modulation and coding strategy (MCS) level between different ranks. The following introduces these two rank adaptive CQI reconstruction schemes respectively.

[0083] The non-codebook solution uses the accurate downlink channel to construct a downlink transmission coefficient that matches the channel, thereby obtaining a shaping gain. The terminal usually performs CQI measurement based on the codebook method. When the macro station performs non-codebook downlink transmission, the downlink shaping gain of the non-codebook transmission is usually higher than that of the codebook. Therefore, the network equipment can estimate the downlink non-codebook shaping gain using the uplink channel estimation and the downlink non-codebook shaping coefficient to be used. The reconstructed CQI can be expressed as the sum of the CQI reporting amount based on the codebook feedback and the CQI correction amount corresponding to the non-codebook shaping gain, as shown in the following formula (1):

[0084] CQI′=CQI PMI +ΔCQI noCodeBookBF (1)

[0085] Among them, CQI PMI is the CQI reporting amount based on codebook feedback, ΔCQInoCodeBookBF is the CQI correction amount corresponding to the non-codebook shaping gain, and CQI′ is the reconstructed CQI.

[0086] Codebook shaping relies on the terminal to select the codebook for transmission. The terminal knows the downlink channel, selects a rank that it believes meets the current channel conditions, and selects a suitable codebook for transmission in the codebook set. At the same time, it measures the corresponding CQI and reports it to the network device. The network device can perform adaptive rank selection based on the rank reported by the terminal, the currently scheduled rank, and the currently scheduled CQI, and reconstruct the CQI under the target rank. The codebook solution usually uses the CQI reconstruction method to use the CQI of the currently scheduled rank, and fall back or increase the fixed MCS level, as shown in the following formula (2):

[0087] CQI rank2 =CQI rank1 -ΔCQI rank1-rank2 (2)

[0088] Among them, CQI rank2 is the reconstructed CQI, CQI rank1 is the CQI of the currently scheduled rank, ΔCQI rank1-rank2 Fixed MCS level for fallback or increase.

[0089] In summary, for large-scale antenna scenarios, it is usually necessary to calibrate the transmit and receive antennas, accurately obtain the downlink channel through the uplink channel information, and perform non-codebook shaping and CQI reconstruction.

[0090] For indoor distributed systems, since indoor distributed systems usually do not perform phase calibration between channels, it is impossible to obtain the accurate downlink channel through the uplink channel information. Therefore, non-codebook transmission cannot be adopted, and thus the non-codebook CQI reconstruction scheme of the macro station cannot be used to calculate the downlink shaping gain through the uplink channel information.

[0091] On the other hand, the antenna forms used in indoor distributed systems are diverse, including pico base stations (pico Radio Remote Unit, pico RRU) composed of single-polarized antennas and indoor distributed antenna systems (Distributed Antenna System, DAS) composed of dual-polarized antennas. At the same time, multi-point deployment is adopted, and the air interface transmission environment is also more complex. Therefore, the multi-stream transmission capabilities in different scenarios vary greatly. The fallback amount between the CQI of the current scheduled stream and the CQI of the target stream also varies greatly in different situations.

[0092] For the indoor distributed system environment, directly using the macro station codebook CQI reconstruction solution, there is a problem that the CQI fallback value cannot accurately reflect the performance fallback between ranks. For example, pico uses a single-polarized antenna, so in the Line of Sight (Loss) scenario, the CQI fallback of stream 2 is larger than that of stream 1; while DAS uses a dual-polarized antenna, which is easier to use 2 streams. In most cases, the throughput of stream 2 = the throughput of stream 1 * 2, and the CQI fallback of stream 2 relative to stream 1 is very small. Therefore, when rank-adaptively reconstructing CQI, if the method used by the macro station codebook is referred to (directly fallback from the CQI of the currently scheduled rank value to several fixed MCS levels), it is impossible to adapt to different scenarios and different antenna forms.

[0093] Based on this, the embodiment of the present application provides a method for determining the CQI fallback amount to achieve CQI fallback in the indoor distributed system. Figure 1 The solution of the embodiment of the present application is introduced.

[0094] Figure 1 A flow chart of a method for determining a CQI fallback amount provided in an embodiment of the present application is provided, and the method is applied to a network device, such as Figure 1 As shown, the method includes:

[0095] S11, when the number of space division multiplexing streams between the network device and the terminal changes, obtaining an uplink channel correlation matrix of the uplink channel between the network device and the terminal.

[0096] The performance of multi-stream between network equipment and terminals mainly depends on the size of inter-stream interference, and the channel multipath richness, network equipment and terminal antenna form, terminal detection scheme, network equipment side downlink shaping transmission scheme and other information are closely related to the size of inter-stream interference. If the above information is known, the signal to interference plus noise ratio (SINR) of the multi-stream can be estimated on the network equipment side, and the CQI of the multi-stream can be converted accordingly to determine the CQI fallback amount.

[0097] However, since most of the current indoor distributed systems do not have channel calibration, the channels of the uplink and downlink antenna ports are not reciprocal, and the uplink channel information cannot be used directly to calculate the downlink SINR. Despite this, the uplink and downlink air interface channels can be considered to be reciprocal in the time division duplexing (TDD) system, and some statistical characteristics of the uplink channel information can be used to approximately convert the interference between the downlink streams, thereby obtaining the SINR fallback from multiple streams to a single stream. In other words, although the uplink channel information cannot be used to directly calculate the downlink SINR, some statistical characteristics of the uplink channel information can be used to approximate the SINR conversion. By mapping the corresponding SINR changes by extracting channel feature values, the channel characteristics in different scenarios can be more flexibly matched.

[0098] In a possible implementation manner, the network device may perform channel estimation on an uplink channel between the network device and the terminal to obtain an uplink channel estimation matrix.

[0099] Assume that the air interface channel matrix between the network device and the terminal is H, where H is a matrix with a dimension of Rx*Tx, where Rx is the number of receiving antennas on the network device side, and Tx is the number of transmitting antennas on the terminal side.

[0100] The phase deviation between the uplink and downlink channels of the network device and the terminal is expressed as E, and the expression of E is shown in the following formula (3):

[0101]

[0102] Where Tx is the number of transmitting antennas on the terminal side, θ k The phase angle between the antennas can be used as a reference for any of the Tx antennas. k It represents the phase angle between the kth antenna and the reference antenna.

[0103] After obtaining the air interface channel matrix H and the inter-channel phase deviation E, the uplink channel estimation matrix H can be obtained based on the air interface channel matrix H and the inter-channel phase deviation E. UL , the calculation method can be found in the following formula (4):

[0104] H UL =H*E (4)

[0105] In obtaining the uplink channel estimation matrix H UL Then, according to the uplink channel estimation matrix H UL , and the conjugate transposed matrix of the uplink channel estimation matrix, the uplink channel correlation matrix can be obtained. The calculation method can be seen in the following formula (5):

[0106] RH UL =H ULJ *H UL (5)

[0107] Among them, RH UL is the uplink channel correlation matrix, H UL is the uplink channel estimation matrix, H UL H is the conjugate transposed matrix of the uplink channel estimation matrix.

[0108] S12, determining a characteristic index value of a downlink channel between the network device and the terminal according to the value of each element in the uplink channel correlation matrix.

[0109] In the above equation (5), the solution of the uplink channel correlation matrix RH is exemplified. UL The uplink channel correlation matrix RH UL It can also be expressed as the following formula (6):

[0110] RH UL =(H*E) H *(H*E)=E H *RH*E (6)

[0111] Among them, RH UL is the uplink channel correlation matrix, H is the air interface channel matrix, E is the inter-channel phase deviation, RH is the air interface channel correlation matrix, RH = H H *H.

[0112] set up:

[0113]

[0114] Among them, R ij The element in the i-th row and j-th column in the correlation matrix RH of the air interface signal is represented, where i is an integer greater than or equal to 1 and less than or equal to n, and j is an integer greater than or equal to 1 and less than or equal to n.

[0115] Substituting equation (3) and equation (6) into equation (7), we get:

[0116]

[0117] Through derivation, it is found that the phase error between channels only causes the correlation matrix RH of the air interface channel and the correlation matrix RH of the uplink channel. UL The phase angle change of the non-diagonal elements between does not affect the amplitude. Therefore, even without inter-channel phase calibration, the uplink channel estimation matrix H can be used ULSome characteristic index values ​​of the air interface channel matrix H are extracted (which can reflect the richness of the air interface channel multipath) for inter-stream interference estimation and CQI correction of rank adaptive switching. Among them, these extracted characteristic index values ​​can reflect the richness of the air interface channel multipath, and the correlation matrix RH of the air interface channel and the uplink channel correlation matrix RH UL are completely equal.

[0118] Specifically, after obtaining the uplink channel correlation matrix, the network device determines the characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix, wherein the characteristic index value of the uplink channel is equal to the characteristic index value of the downlink channel. After determining the characteristic index value of the uplink channel, since the characteristic index value of the uplink channel is equal to the characteristic index value of the downlink channel, the characteristic index value of the uplink channel can be directly determined as the characteristic index value of the downlink channel.

[0119] The following describes how to determine the characteristic indicator value of the uplink channel.

[0120] In one implementation, when determining the uplink channel correlation matrix RH UL After that, the network equipment calculates the uplink channel correlation matrix RH UL The complex amplitudes of multiple diagonal elements in are summed to obtain the first complex amplitude, and then the uplink channel correlation matrix RH is UL The complex amplitudes of multiple non-diagonal elements in are summed to obtain a second complex amplitude, and the ratio of the second complex amplitude to the first complex amplitude is determined as the characteristic index value of the uplink channel. The above calculation process can be referred to the following formula (9):

[0121]

[0122] Among them, AmpFactor rankn is the characteristic index value of the uplink channel; RH(i,j) represents the element of the i-th row and j-th column of the correlation matrix RH of the air interface channel;

[0123] When i=j, RH(i,j) belongs to the diagonal element of the correlation matrix RH of the air interface channel. The sum of the complex amplitudes of all diagonal elements of the correlation matrix RH representing the air interface channel;

[0124] When i≠j, RH(i,j) belongs to the off-diagonal elements of the correlation matrix RH of the air interface channel. The sum of the complex amplitudes of all off-diagonal elements of the correlation matrix RH representing the air interface channel;

[0125] RH UL (i,j) represents the uplink channel correlation matrix RH UL The element in the i-th row and j-th column of ;

[0126] When i=j, RH UL (i,j) belongs to the uplink channel correlation matrix RH UL The elements on the diagonal of Denotes the uplink channel correlation matrix RH UL The sum of the complex amplitudes of all diagonal elements, that is, the first complex amplitude;

[0127] When i≠j, RH UL (i,j) belongs to the uplink channel correlation matrix RH UL The off-diagonal elements of Denotes the uplink channel correlation matrix RH UL The sum of the complex amplitudes of all non-diagonal elements, that is, the second complex amplitude;

[0128] Among them, it also meets:

[0129]

[0130]

[0131] AmpFactor, the characteristic index value of the uplink channel rankn , reflects the correlation between channels of different antennas. The larger the value, the less multipath, and the smaller the value, the more multipath. In the case of pure Loss, different antennas only differ by a fixed phase, and the antennas are completely correlated. The values ​​on the non-diagonal elements are large. This embodiment uses the uplink channel correlation matrix RH UL The ratio of the sum of the complex amplitudes of the off-diagonal elements to the sum of the complex amplitudes of the diagonal elements is used to estimate the CQI fallback amount between different ranks of the downlink channel.

[0132] In one implementation, when determining the uplink channel correlation matrix RH UL After that, the network equipment calculates the uplink channel correlation matrix RH UL Perform eigenvalue decomposition to obtain the uplink channel correlation matrix RH UL The characteristic value of .

[0133] Assume that the uplink channel correlation matrix RH UL The eigenvalues ​​of are recorded from large to small as λ1, λ2, ..., λ maxrank, where maxrank represents the maximum number of streams that can be scheduled by the channel, and its value is related to the number of transmit and receive antennas. For example, a channel with 4 transmit / receive (TR) can transmit up to 4 streams, so maxrank = 4. Let the number of streams actually scheduled be rankn, which is usually less than maxrank. For the maxrank eigenvalues, the network device takes rankn eigenvalues, which are λ1, λ2, ..., λ1 from large to small. rankn .

[0134] Then, in the range from λ1 to λ rankn Among these multiple eigenvalues, determine the first eigenvalue with the largest value and the second eigenvalue with the smallest value. Taking maxrank=4 as an example, if the number of actually scheduled streams rankn=2, the multiple eigenvalues ​​determined by the network device include λ1 and λ2, where the first eigenvalue is λ1 and the second eigenvalue is λ2; if the number of actually scheduled streams rankn=3, the multiple eigenvalues ​​determined by the network device include λ1, λ2, and λ3, where the first eigenvalue is λ1 and the second eigenvalue is λ3. The same is true when maxrank and rankn take other values, which will not be repeated here. After determining the first eigenvalue and the second eigenvalue, the network device determines the ratio of the second eigenvalue to the first eigenvalue as the characteristic index value of the uplink channel. The above calculation process can be found in the following formula (10):

[0135]

[0136] Among them, EigFactor rankn is the characteristic index value of the uplink channel, λ1 is the first characteristic value, λ rankn is the second eigenvalue.

[0137] EigFactor, the characteristic index value of the uplink channel rankn , can also reflect the correlation degree of channels between different antennas. The larger the value, the richer the multipath, for example, the eigenvalues ​​of the non-line of sight (NLos) channel are closer; the smaller the value, the fewer the multipath, for example, the difference between the eigenvalues ​​of the Los channel is large. This embodiment uses the uplink channel correlation matrix RH UL The ratio of the minimum eigenvalue to the maximum eigenvalue of the downlink channel is used to estimate the CQI fallback amount between different ranks of the downlink channel.

[0138] S13, determining, according to the characteristic indicator value of the downlink channel, a CQI fallback amount of the downlink channel after the number of space division multiplexing streams changes.

[0139] Since the characteristic index value of the uplink channel is equal to the characteristic index value of the downlink channel, after the characteristic index value of the uplink channel is determined according to the method of the above example, the characteristic index value of the downlink channel can be obtained.

[0140] Then, obtain the mapping relationship between the characteristic indicator value range and the CQI backoff amount. Among them, the mapping relationship can be obtained in advance by statistical means. For example, in the case where the number of space-division multiplexing streams between the network device and the terminal changes, the characteristic indicator value of the downlink channel is calculated by the above method, and then the channel quality after different CQI backoff amounts under the same characteristic indicator value is calculated through different CQI backoff amounts of the device, so as to determine the appropriate CQI backoff amount under the characteristic indicator value. In this way, the corresponding relationship between multiple groups of characteristic indicator values ​​and CQI backoff amounts can be calculated, and then the mapping relationship between the characteristic indicator value range and the CQI backoff amount can be obtained by means of a table or a curve fitting method.

[0141] After obtaining the mapping relationship between the characteristic indicator value range and the CQI backoff amount, the network device determines the target characteristic indicator value range to which the characteristic indicator value of the downlink channel belongs in multiple characteristic indicator value ranges, and thus determines the CQI backoff amount corresponding to the target characteristic indicator value range as the CQI backoff amount of the downlink channel based on the mapping relationship between the characteristic indicator value range and the CQI backoff amount.

[0142] The following is an introduction with two specific examples.

[0143] If the characteristic index value of the downlink channel is AmpFactor in the above formula (9) rankn , the network device can obtain AmpFactor in advance rankn The mapping relationship between the corresponding characteristic indicator value range and the CQI fallback amount. The following table 1 illustrates a possible mapping relationship, as shown in the following table 1, which illustrates AmpFactor rankn The corresponding multiple characteristic index value ranges are <-6dB, [-6, -3)dB, [-3, 0)dB, >0dB. Each characteristic index value range has a corresponding CQI fallback amount, that is, the MCS fallback amount MCS between rank1 and rankn rank1-rank .

[0144] Table 1

[0145]

[0146] If AmpFactor rankn is -2, the corresponding target characteristic index value range is [-3,0)dB, and the corresponding CQI fallback is 15; if AmpFactor ranknIf it is -5, the corresponding target characteristic index value range is [-6,-3)dB, and the corresponding CQI backoff amount is 10, and so on.

[0147] If the characteristic index value of the downlink channel is EigFactor in the above formula (10) rankn , the network device can obtain EigFactor in advance rankn The mapping relationship between the corresponding characteristic indicator value range and the CQI fallback amount. Table 2 below illustrates a possible mapping relationship, as shown in Table 2 below, which illustrates EigFactor rankn The corresponding multiple characteristic indicator value ranges are <-25dB, [-25, -20)dB, [-20, -15)dB, [-15, -10)dB, [-10, 0)dB. Each characteristic indicator value range has a corresponding CQI fallback amount, that is, the MCS fallback amount MCS between rank1 and rankn rank1-rank .

[0148] Table 2

[0149]

[0150]

[0151] If EigFactor rankn is -22, the corresponding target characteristic index value range is [-25, -20) dB, and the corresponding CQI fallback is 20; if EigFactor rankn If it is -5, the corresponding target characteristic index value range is [-10,0)dB, and the corresponding CQI backoff amount is 5, and so on.

[0152] In summary, the method for determining the CQI fallback amount provided in the embodiment of the present application, when the number of spatial division multiplexing streams between the network device and the terminal changes, obtains the uplink channel correlation matrix of the uplink channel between the network device and the terminal, and then determines the characteristic index value of the downlink channel between the network device and the terminal according to the value of each element in the uplink channel correlation matrix, thereby determining the CQI fallback amount of the downlink channel after the number of spatial division multiplexing streams changes according to the characteristic index value of the downlink channel. The solution provided by the present application estimates the multi-stream transmission capacity of the downlink channel using the uplink channel information, which solves the problem that the uplink channel information cannot be used directly to accurately reconstruct the CQI without performing channel calibration in the indoor scenario. It can adapt to the rank adaptive CQI reconstruction requirements under different scenarios and antenna forms. The characteristic index value of the downlink channel is estimated by the uplink channel correlation matrix, thereby determining the CQI fallback amount of the downlink channel, without the need to calibrate the transceiver antenna, and can be applied to the determination of the CQI fallback amount in the indoor system.

[0153] Figure 2 A schematic diagram of the structure of a network device provided in an embodiment of the present application is shown in FIG. Figure 2 As shown, the network device includes a memory 220, a transceiver 200, and a processor 210, wherein:

[0154] The memory 220 is used to store computer programs; the transceiver 200 is used to send and receive data under the control of the processor 210; the processor 210 is used to read the computer program in the memory 220 and perform the following operations:

[0155] When the number of space division multiplexing streams between the network device and the terminal changes, acquiring an uplink channel correlation matrix of an uplink channel between the network device and the terminal;

[0156] Determining a characteristic index value of a downlink channel between the network device and the terminal according to a value of each element in the uplink channel correlation matrix;

[0157] According to the characteristic indicator value of the downlink channel, a CQI fallback amount of the downlink channel is determined after the number of spatial division multiplexing streams changes.

[0158] Specifically, the transceiver 200 is used to receive and send data under the control of the processor 210.

[0159] Among them, Figure 2 In the embodiment, the bus architecture may include any number of interconnected buses and bridges, specifically linking together various circuits of one or more processors represented by processor 210 and memory represented by memory 220. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. The bus interface provides an interface. The transceiver 200 may be a plurality of components, namely, a transmitter and a receiver, providing a unit for communicating with various other devices on a transmission medium, which may include transmission media such as wireless channels, wired channels, optical cables, etc. The processor 210 is responsible for managing the bus architecture and general processing, and the memory 220 may store data used by the processor 210 when performing operations.

[0160] Optionally, the processor 210 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or a complex programmable logic device (CPLD), and the processor may also adopt a multi-core architecture.

[0161] The processor calls the computer program stored in the memory to execute any of the methods provided in the embodiments of the present application according to the obtained executable instructions. The processor and the memory can also be arranged physically separately.

[0162] In a possible implementation manner, determining the characteristic index value of the downlink channel between the network device and the terminal according to the value of each element in the uplink channel correlation matrix includes:

[0163] Determining a characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix, wherein the characteristic index value of the uplink channel is equal to the characteristic index value of the downlink channel;

[0164] The characteristic index value of the uplink channel is determined as the characteristic index value of the downlink channel.

[0165] In a possible implementation manner, determining the characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix includes:

[0166] Determining the sum of the complex amplitudes of a plurality of diagonal elements in the uplink channel correlation matrix as a first complex amplitude;

[0167] Determining the sum of the complex amplitudes of a plurality of off-diagonal elements in the uplink channel correlation matrix as a second complex amplitude;

[0168] The ratio of the second complex amplitude to the first complex amplitude is determined as the characteristic index value of the uplink channel.

[0169] In a possible implementation manner, determining the characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix includes:

[0170] Performing eigenvalue decomposition on the uplink channel correlation matrix to obtain multiple eigenvalues ​​of the uplink channel correlation matrix;

[0171] Determine a first eigenvalue having a maximum value and a second eigenvalue having a minimum value among the multiple eigenvalues;

[0172] The ratio of the second characteristic value to the first characteristic value is determined as the characteristic index value of the uplink channel.

[0173] In a possible implementation manner, determining, according to the characteristic indicator value of the downlink channel, the CQI fallback amount of the downlink channel after the number of spatial division multiplexing streams changes, includes:

[0174] Obtaining a mapping relationship between a characteristic indicator value range and a CQI fallback amount;

[0175] In the characteristic indicator value range, determining a target characteristic indicator value range to which the characteristic indicator value of the downlink channel belongs;

[0176] According to the mapping relationship, the CQI backoff amount corresponding to the target characteristic indicator value range is determined as the CQI backoff amount of the downlink channel.

[0177] In a possible implementation manner, the acquiring an uplink channel correlation matrix of an uplink channel between the network device and the terminal includes:

[0178] Performing channel estimation on the uplink channel to obtain an uplink channel estimation matrix;

[0179] The uplink channel correlation matrix is ​​acquired according to the uplink channel estimation matrix and the conjugate transposed matrix of the uplink channel estimation matrix.

[0180] Figure 3 A schematic diagram of the structure of the device for determining the CQI fallback amount provided in an embodiment of the present application, such as Figure 3 As shown, the device comprises:

[0181] An acquisition module 31, configured to acquire an uplink channel correlation matrix of an uplink channel between the network device and the terminal when the number of space division multiplexing streams between the network device and the terminal changes;

[0182] A processing module 32, configured to determine a characteristic index value of a downlink channel between the network device and the terminal according to a value of each element in the uplink channel correlation matrix;

[0183] The determination module 33 is used to determine, according to the characteristic indicator value of the downlink channel, the CQI fallback amount of the downlink channel after the number of the spatial division multiplexing streams changes.

[0184] In a possible implementation manner, the processing module 32 is specifically configured to:

[0185] Determining a characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix, wherein the characteristic index value of the uplink channel is equal to the characteristic index value of the downlink channel;

[0186] The characteristic index value of the uplink channel is determined as the characteristic index value of the downlink channel.

[0187] In a possible implementation manner, the processing module 32 is specifically configured to:

[0188] Determining the sum of the complex amplitudes of a plurality of diagonal elements in the uplink channel correlation matrix as a first complex amplitude;

[0189] Determining the sum of the complex amplitudes of a plurality of off-diagonal elements in the uplink channel correlation matrix as a second complex amplitude;

[0190] The ratio of the second complex amplitude to the first complex amplitude is determined as the characteristic index value of the uplink channel.

[0191] In a possible implementation manner, the processing module 32 is specifically configured to:

[0192] Performing eigenvalue decomposition on the uplink channel correlation matrix to obtain multiple eigenvalues ​​of the uplink channel correlation matrix;

[0193] Determine a first eigenvalue having a maximum value and a second eigenvalue having a minimum value among the multiple eigenvalues;

[0194] The ratio of the second characteristic value to the first characteristic value is determined as the characteristic index value of the uplink channel.

[0195] In a possible implementation manner, the determining module 33 is specifically configured to:

[0196] Obtaining a mapping relationship between a characteristic indicator value range and a CQI fallback amount;

[0197] In the characteristic indicator value range, determining a target characteristic indicator value range to which the characteristic indicator value of the downlink channel belongs;

[0198] According to the mapping relationship, the CQI backoff amount corresponding to the target characteristic indicator value range is determined as the CQI backoff amount of the downlink channel.

[0199] In a possible implementation manner, the acquisition module 31 is specifically used to:

[0200] Performing channel estimation on the uplink channel to obtain an uplink channel estimation matrix;

[0201] The uplink channel correlation matrix is ​​acquired according to the uplink channel estimation matrix and the conjugate transposed matrix of the uplink channel estimation matrix.

[0202] Specifically, the above-mentioned device for determining the CQI backoff amount provided in the embodiment of the present application can implement all the method steps implemented by the method embodiment in which the execution subject is a network device, and can achieve the same technical effect. The parts and beneficial effects of this embodiment that are the same as those of the method embodiment will not be described in detail here.

[0203] It should be noted that the division of units / modules in the above embodiments of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation. In addition, the functional units in the various embodiments of the present application may be integrated into a processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated units may be implemented in the form of hardware or in the form of software functional units.

[0204] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a processor-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) or a processor (processor) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program codes.

[0205] In some embodiments, a computer-readable storage medium is further provided, wherein the computer-readable storage medium stores a computer program, wherein the computer program is used to enable a computer to execute the method for determining the CQI backoff amount provided in the above-mentioned method embodiments.

[0206] Specifically, the above-mentioned computer-readable storage medium provided in the embodiment of the present application can implement all the method steps implemented by the above-mentioned method embodiments, and can achieve the same technical effect. The parts and beneficial effects of this embodiment that are the same as the method embodiment will not be described in detail here.

[0207] It should be noted that the computer-readable storage medium can be any available medium or data storage device that can be accessed by the processor, including but not limited to magnetic storage (such as floppy disks, hard disks, magnetic tapes, magneto-optical disks (MO), etc.), optical storage (such as CD, DVD, BD, HVD, etc.), and semiconductor storage (such as ROM, EPROM, EEPROM, non-volatile memory (NAND FLASH), solid-state drive (SSD)), etc.

[0208] It should also be noted that the terms "first", "second", etc. in the embodiments of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first" and "second" are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0209] In the embodiments of the present application, the term "and / or" describes the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0210] In the embodiments of the present application, the term "plurality" refers to two or more than two, and other quantifiers are similar.

[0211] The technical solution provided in the embodiment of the present application can be applicable to a variety of systems, especially 5G systems. For example, the applicable system can be a global system of mobile communication (GSM) system, a code division multiple access (CDMA) system, a wideband code division multiple access (WCDMA) general packet radio service (GPRS) system, a long term evolution (LTE) system, a LTE frequency division duplex (FDD) system, a LTE time division duplex (TDD) system, an advanced long term evolution (LTE-A) system, a universal mobile telecommunication system (UMTS), a world-wide interoperability for microwave access (WiMAX) system, a 5G new air interface (NR) system, etc. These various systems include terminal equipment and network equipment. The system may also include a core network part, such as an evolved packet system (EPS), a 5G system (5GS), etc.

[0212] The terminal device involved in the embodiment of the present application may be a device that provides voice and / or data connectivity to a user, a handheld device with a wireless connection function, or other processing devices connected to a wireless modem. In different systems, the name of the terminal device may also be different. For example, in a 5G system, the terminal device may be called a user equipment (UE). A wireless terminal device can communicate with one or more core networks (CN) via a radio access network (RAN). The wireless terminal device may be a mobile terminal device, such as a mobile phone (or a "cellular" phone) and a computer with a mobile terminal device. For example, it may be a portable, pocket-sized, handheld, computer-built-in or vehicle-mounted mobile device that exchanges language and / or data with a wireless access network. For example, personal communication service (PCS) phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs) and other devices. The wireless terminal device may also be referred to as a system, a subscriber unit, a subscriber station, a mobile station, a mobile station, a remote station, an access point, a remote terminal device, an access terminal device, a user terminal device, a user agent, and a user device, but is not limited in the embodiments of the present application.

[0213] The network device involved in the embodiment of the present application may be a base station, which may include multiple cells providing services for the terminal. Depending on the specific application scenario, the base station may also be called an access point, or may be a device in the access network that communicates with the wireless terminal device through one or more sectors on the air interface, or other names. The network device may be used to interchange received air frames with Internet Protocol (IP) packets, and serve as a router between the wireless terminal device and the rest of the access network, wherein the rest of the access network may include an Internet Protocol (IP) communication network. The network device may also coordinate the attribute management of the air interface. For example, the network device involved in the embodiments of the present application may be a network device (Base Transceiver Station, BTS) in the Global System for Mobile communications (Global System for Mobile communications, GSM) or Code Division Multiple Access (Code Division Multiple Access, CDMA), or a network device (NodeB) in Wide-band Code Division Multiple Access (WCDMA), or an evolutionary network device (evolutional Node B, eNB or e-NodeB) in the long term evolution (long term evolution, LTE) system, a 5G base station (gNB) in the 5G network architecture (next generation system), or a home evolved Node B (Home evolved Node B, HeNB), a relay node, a home base station (femto), a pico base station (pico), etc., which is not limited in the embodiments of the present application. In some network structures, the network device may include a centralized unit (CU) node and a distributed unit (DU) node, and the centralized unit and the distributed unit may also be arranged geographically separately.

[0214] Network devices and terminal devices can each use one or more antennas for multiple-input multiple-output (MIMO) transmission. MIMO transmission can be single-user MIMO (SU-MIMO) or multi-user MIMO (MU-MIMO). Depending on the form and number of antenna combinations, MIMO transmission can be 2D-MIMO, 3D-MIMO, FD-MIMO or massive-MIMO, or it can be diversity transmission, precoded transmission or beamforming transmission, etc.

[0215] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) that contain computer-usable program code.

[0216] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer executable instructions. These computer executable instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0217] These processor executable instructions may also be stored in a processor readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the processor readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0218] These processor-executable instructions may also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable device to implement the process. Figure 1A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0219] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for determining a channel quality index CQI backoff amount, characterized in that: Applied to a network device, the method comprises: When the number of space division multiplexing streams between the network device and the terminal changes, acquiring an uplink channel correlation matrix of an uplink channel between the network device and the terminal; Determining a characteristic index value of a downlink channel between the network device and the terminal according to a value of each element in the uplink channel correlation matrix; According to the characteristic indicator value of the downlink channel, a CQI fallback amount of the downlink channel is determined after the number of spatial division multiplexing streams changes.

2. The method according to claim 1, characterized in that: The determining, according to the value of each element in the uplink channel correlation matrix, a characteristic index value of the downlink channel between the network device and the terminal includes: Determining a characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix, wherein the characteristic index value of the uplink channel is equal to the characteristic index value of the downlink channel; The characteristic index value of the uplink channel is determined as the characteristic index value of the downlink channel.

3. The method according to claim 2, characterized in that The determining the characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix includes: Determining the sum of the complex amplitudes of a plurality of diagonal elements in the uplink channel correlation matrix as a first complex amplitude; Determining the sum of the complex amplitudes of a plurality of off-diagonal elements in the uplink channel correlation matrix as a second complex amplitude; The ratio of the second complex amplitude to the first complex amplitude is determined as the characteristic index value of the uplink channel.

4. The method according to claim 2, characterized in that: The determining the characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix includes: Performing eigenvalue decomposition on the uplink channel correlation matrix to obtain multiple eigenvalues ​​of the uplink channel correlation matrix; Determine a first eigenvalue having a maximum value and a second eigenvalue having a minimum value among the multiple eigenvalues; The ratio of the second characteristic value to the first characteristic value is determined as the characteristic index value of the uplink channel.

5. The method according to any one of claims 1 to 4, characterized in that: The determining, according to the characteristic indicator value of the downlink channel, a CQI fallback amount of the downlink channel after the number of spatial division multiplexing streams changes, includes: Obtaining a mapping relationship between a characteristic indicator value range and a CQI fallback amount; In the characteristic indicator value range, determining a target characteristic indicator value range to which the characteristic indicator value of the downlink channel belongs; According to the mapping relationship, the CQI backoff amount corresponding to the target characteristic indicator value range is determined as the CQI backoff amount of the downlink channel.

6. The method according to any one of claims 1 to 4, characterized in that: The acquiring an uplink channel correlation matrix of an uplink channel between the network device and the terminal includes: Performing channel estimation on the uplink channel to obtain an uplink channel estimation matrix; The uplink channel correlation matrix is ​​acquired according to the uplink channel estimation matrix and the conjugate transposed matrix of the uplink channel estimation matrix.

7. A network device, characterized in that: Including memory, transceiver, processor; A memory for storing a computer program; a transceiver for transmitting and receiving data under the control of the processor; and a processor for reading the computer program in the memory and performing the following operations: When the number of space division multiplexing streams between the network device and the terminal changes, acquiring an uplink channel correlation matrix of an uplink channel between the network device and the terminal; Determining a characteristic index value of a downlink channel between the network device and the terminal according to a value of each element in the uplink channel correlation matrix; According to the characteristic indicator value of the downlink channel, a CQI fallback amount of the downlink channel is determined after the number of spatial division multiplexing streams changes.

8. The network device according to claim 7, characterized in that: The determining, according to the value of each element in the uplink channel correlation matrix, a characteristic index value of the downlink channel between the network device and the terminal includes: Determining a characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix, wherein the characteristic index value of the uplink channel is equal to the characteristic index value of the downlink channel; The characteristic index value of the uplink channel is determined as the characteristic index value of the downlink channel.

9. The network device according to claim 8, characterized in that: The determining the characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix includes: Determining the sum of the complex amplitudes of a plurality of diagonal elements in the uplink channel correlation matrix as a first complex amplitude; Determining the sum of the complex amplitudes of a plurality of off-diagonal elements in the uplink channel correlation matrix as a second complex amplitude; The ratio of the second complex amplitude to the first complex amplitude is determined as the characteristic index value of the uplink channel.

10. The network device according to claim 8, characterized in that: The determining the characteristic index value of the uplink channel according to the value of each element in the uplink channel correlation matrix includes: Performing eigenvalue decomposition on the uplink channel correlation matrix to obtain multiple eigenvalues ​​of the uplink channel correlation matrix; Determine a first eigenvalue having a maximum value and a second eigenvalue having a minimum value among the multiple eigenvalues; The ratio of the second characteristic value to the first characteristic value is determined as the characteristic index value of the uplink channel.

11. The network device according to any one of claims 7 to 10, characterized in that: The determining, according to the characteristic indicator value of the downlink channel, a CQI fallback amount of the downlink channel after the number of spatial division multiplexing streams changes, includes: Obtaining a mapping relationship between a characteristic indicator value range and a CQI fallback amount; In the characteristic indicator value range, determining a target characteristic indicator value range to which the characteristic indicator value of the downlink channel belongs; According to the mapping relationship, the CQI backoff amount corresponding to the target characteristic indicator value range is determined as the CQI backoff amount of the downlink channel.

12. The network device according to any one of claims 7 to 10, characterized in that: The acquiring an uplink channel correlation matrix of an uplink channel between the network device and the terminal includes: Performing channel estimation on the uplink channel to obtain an uplink channel estimation matrix; The uplink channel correlation matrix is ​​acquired according to the uplink channel estimation matrix and the conjugate transposed matrix of the uplink channel estimation matrix.

13. A device for determining a CQI fallback amount, characterized in that: Applied to network equipment, the device comprises: An acquisition module, configured to acquire an uplink channel correlation matrix of an uplink channel between the network device and the terminal when the number of space division multiplexing streams between the network device and the terminal changes; A processing module, used to determine a characteristic index value of a downlink channel between the network device and the terminal according to the value of each element in the uplink channel correlation matrix; The determination module is used to determine, according to the characteristic indicator value of the downlink channel, the CQI fallback amount of the downlink channel after the number of spatial division multiplexing streams changes.

14. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is used to cause a computer to execute the method for determining a CQI backoff amount according to any one of claims 1 to 6.

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