Calibration method and device between RRUs and storage medium

Abstract

The invention provides a calibration method and device between RRUs and a storage medium, and relates to the technical field of communication. The method comprises the following steps: determining a calibration antenna in N antennas of each RRU; sending the first calibration sequence through one antenna in the M calibration antennas, and receiving and processing the first calibration sequence through other (M-1) calibration antennas except the antenna in the M calibration antennas to obtain (M-1) second calibration sequences; sending the first calibration sequence through M-1 calibration antennas, and receiving and processing the first calibration sequence through one antenna to obtain M-1 third calibration sequences; and performing calibration processing on the M RRUs according to the M-1 second calibration sequences and the M-1 third calibration sequences. The calibration of all RRUs can be completed through one round of calibration of one calibration antenna in each RRU, and the overhead of RRU calibration calculation is reduced.

Description

Technical Field

[0001] This application relates to the field of communication technologies, and in particular, to a calibration method, apparatus, and storage medium for remote radio units (RRUs). Background Art

[0002] In a large-scale massive multi-input multi-output (massive MIMO) system, spatial narrow beamforming is formed through a large number of antennas, and the spatial dimension is fully utilized to obtain multi-user multiplexing gain, which can effectively improve the cell spectral efficiency and capacity. During the use of antennas, the phase and amplitude of the antenna paths may change due to environmental factors and other reasons. Therefore, it is necessary to calibrate the antennas to perform beamforming accurately.

[0003] In the related art, remote radio frequency units (RRUs) usually perform self-calibration using the air interface wireless propagation channel. That is, first, a reference RRU is selected from multiple RRUs, a calibration sequence is sent through the reference antenna in the reference RRU, and then the calibration sequence is received by all antennas in other RRUs, and other RRUs are calibrated based on the calibration sequences before and after reception. Since there is a situation where the reference RRU cannot be calibrated in each round of calibration, it is necessary to replace the reference RRU and perform a second round of calibration. The multi-round calibration process results in a large overhead for RRU calibration calculations. Summary of the Invention

[0004] This application provides a calibration method, apparatus, and storage medium for RRUs, which solves the technical problem of large overhead in existing RRU calibration calculations.

[0005] In a first aspect, an embodiment of this application provides a calibration method for RRUs, which is applied to a network device. M RRUs are provided on the network device, and N antennas are provided on each RRU, where M is a positive integer greater than 1, and N is a positive integer greater than 1. The method includes:

[0006] Determine one calibration antenna among the N antennas of each RRU;

[0007] Send a first calibration sequence through one of the M calibration antennas, and receive and process through the other M - 1 calibration antennas among the M calibration antennas to obtain M - 1 second calibration sequences;

[0008] Send the first calibration sequence through the M - 1 calibration antennas, and receive and process through the one antenna to obtain M - 1 third calibration sequences;

[0009] Calibrate the M RRU according to the M-1 second calibration sequences and the M-1 third calibration sequences.

[0010] In one embodiment, the calibrating the M RRU according to the M-1 second calibration sequences and the M-1 third calibration sequences includes:

[0011] Determine M-1 first channel matrices according to the M-1 second calibration sequences;

[0012] Determine M-1 second channel matrices according to the M-1 third calibration sequences;

[0013] Determine calibration factors between M-1 RRU according to the M-1 first channel matrices and the M-1 second channel matrices;

[0014] Calibrate the M RRU according to the calibration factors between M-1 RRU.

[0015] In one embodiment, determining the calibration factors between M-1 RRU according to the M-1 first channel matrices and the M-1 second channel matrices includes:

[0016] For any one of the first channel matrices, determine an initial calibration factor between RRU according to the first channel matrix and the second channel matrix corresponding to the first channel matrix;

[0017] Determine the calibration factors between M-1 RRU according to the M-1 initial calibration factors between RRU.

[0018] In one embodiment, determining the initial calibration factor between RRU according to the first channel matrix and the second channel matrix corresponding to the first channel matrix includes:

[0019] Determine the initial calibration factor between RRU through the following formula:

[0020]

[0021] where c r→i (k) is the initial calibration factor between RRU; is the first channel matrix; is the second channel matrix; i is the identifier of the first RRU, and the first RRU is the RRU where the one antenna is located; r is the identifier of the second RRU, and the second RRU is the RRU where any one of the M-1 calibration antennas is located; j1 is the identifier of the one antenna; m1 is the identifier of the calibration antenna in the second RRU; k is the identifier of the resource block in the system bandwidth; Q is the number of resource blocks in the system bandwidth.

[0022] In one embodiment, for any initial inter-RRU calibration factor, determining the inter-RRU calibration factor according to the initial inter-RRU calibration factor includes:

[0023] Determining the inter-RRU calibration factor through the following formula:

[0024]

[0025] Wherein, is the inter-RRU calibration factor; c r→i (k) is the initial inter-RRU calibration factor.

[0026] In one embodiment, the calibrating the M RRU according to the M - 1 inter-RRU calibration factors includes:

[0027] Obtaining the intra-RRU calibration factor of each RRU;

[0028] Determining the final calibration factor of each RRU according to the intra-RRU calibration factor of each RRU and the M - 1 inter-RRU calibration factors;

[0029] For any one RRU, calibrating the RRU according to the final calibration factor of the RRU.

[0030] In one embodiment, the determining the final calibration factor of each RRU according to the intra-RRU calibration factor of each RRU and the M - 1 inter-RRU calibration factors includes:

[0031] Taking the intra-RRU calibration factor of the first RRU as the final calibration factor of the first RRU, and taking the product of the intra-RRU calibration factor of the second RRU and the inter-RRU calibration factor corresponding to the second RRU as the final calibration factor of the second RRU;

[0032] Wherein, the first RRU is the RRU where the one antenna is located, and the second RRU is the RRU where any one of the M - 1 calibration antennas is located.

[0033] In one embodiment, if the calibration antenna in the second RRU is not the reference antenna used by the second RRU during internal calibration, the method further includes:

[0034] Correcting the final calibration factor of the second RRU through the following formula:

[0035]

[0036] Wherein, is the final calibration factor after correction for the second RRU, is the final calibration factor of the second RRU, is the calibration factor of the calibration antenna in the second RRU, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

[0037] In one embodiment, determining one calibration antenna among the N antennas of each RRU includes:

[0038] Among the N antennas of each RRU, use the reference antenna used by the RRU during internal calibration as the calibration antenna.

[0039] In one embodiment, determining one calibration antenna among the N antennas of each RRU includes:

[0040] For the first RRU, among the N antennas of the first RRU, use the reference antenna used by the first RRU during internal calibration as the calibration antenna. The first RRU is any one of the M RRUs, and the one antenna is the calibration antenna in the first RRU;

[0041] For the second RRU, among the N antennas of the second RRU, use the antenna with the received quality of the first calibration sequence greater than or equal to the preset threshold as the calibration antenna. The second RRU is any one of the M RRUs other than the first RRU, and the first calibration sequence is sent by the calibration antenna of the first RRU.

[0042] In one embodiment, for any one RRU, the method further includes:

[0043] Determine one antenna among the N antennas as the reference antenna;

[0044] Send the first calibration sequence through the reference antenna, and receive and process through the other N - 1 antennas among the N antennas except the reference antenna to obtain N - 1 fourth calibration sequences;

[0045] Send the first calibration sequence through the N - 1 antennas, and receive and process through the reference antenna to obtain N - 1 fifth calibration sequences;

[0046] Determine the in - RRU calibration factor of the RRU according to the N - 1 fourth calibration sequences and the N - 1 fifth calibration sequences.

[0047] In one embodiment, the determining the in - RRU calibration factor of the RRU according to the N - 1 fourth calibration sequences and the N - 1 fifth calibration sequences includes:

[0048] Determine N - 1 third - channel matrices according to the N - 1 fourth calibration sequences;

[0049] Determine N - 1 fourth - channel matrices according to the N - 1 fifth calibration sequences;

[0050] Determine N - 1 antenna calibration factors according to the N - 1 third - channel matrices and the N - 1 fourth - channel matrices;

[0051] Process the calibration factor of the reference antenna and the N - 1 antenna calibration factors to obtain the in - RRU calibration factor of the RRU.

[0052] In one implementation, the determining N - 1 antenna calibration factors according to the N - 1 third - channel matrices and the N - 1 fourth - channel matrices includes:

[0053] For any one of the third - channel matrices, determine an initial antenna calibration factor according to the third - channel matrix and the fourth - channel matrix corresponding to the third - channel matrix;

[0054] Determine the N - 1 antenna calibration factors according to the N - 1 initial antenna calibration factors.

[0055] In one implementation, the determining an initial antenna calibration factor according to the third - channel matrix and the fourth - channel matrix corresponding to the third - channel matrix includes:

[0056] Determine the initial antenna calibration factor through the following formula:

[0057]

[0058] where c m2 (k) is the initial antenna calibration factor, is the third - channel matrix, is the fourth - channel matrix, j2 is the identifier of the reference antenna; m2 is the identifier of any one of the N - 1 antennas, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

[0059] In one implementation, for any one of the initial antenna calibration factors, determine an antenna calibration factor according to the initial antenna calibration factor, including:

[0060] Determine the antenna calibration factor through the following formula:

[0061]

[0062] where, is the antenna calibration factor, cm2 (k) is the initial antenna calibration factor.

[0063] In a second aspect, an embodiment of the present application provides a calibration device between RRU, which is applied to a network device. There are M RRUs provided on the network device, and N antennas are provided on each RRU. M is a positive integer greater than 1, and N is a positive integer greater than 1. The device includes a memory, a transceiver, and a processor:

[0064] The memory is used to store computer programs; the transceiver is used to transmit and receive data under the control of the processor; the processor is used to read the computer programs in the memory and perform the following operations:

[0065] Determine one calibration antenna among the N antennas of each RRU;

[0066] Send a first calibration sequence through one of the M calibration antennas, and receive and process through the other M - 1 calibration antennas among the M calibration antennas to obtain M - 1 second calibration sequences;

[0067] Send the first calibration sequence through the M - 1 calibration antennas, and receive and process through the one antenna to obtain M - 1 third calibration sequences;

[0068] Calibrate the M RRUs according to the M - 1 second calibration sequences and the M - 1 third calibration sequences.

[0069] In an implementation manner, the processor is specifically used to perform the following operations:

[0070] Determine M - 1 first channel matrices according to the M - 1 second calibration sequences;

[0071] Determine M - 1 second channel matrices according to the M - 1 third calibration sequences;

[0072] Determine M - 1 calibration factors between RRUs according to the M - 1 first channel matrices and the M - 1 second channel matrices;

[0073] Calibrate the M RRUs according to the M - 1 calibration factors between RRUs.

[0074] In an implementation manner, the processor is specifically used to perform the following operations:

[0075] For any one of the first channel matrices, determine an initial calibration factor between RRUs according to the first channel matrix and the second channel matrix corresponding to the first channel matrix;

[0076] Determine the calibration factors between the M - 1 RRU based on the calibration factors between the initial M - 1 RRU.

[0077] In one implementation, the processor is specifically configured to perform the following operations:

[0078] Determine the calibration factors between the initial RRU through the following formula:

[0079]

[0080] where c r→i (k) is the calibration factor between the initial RRU; is the first channel matrix; is the second channel matrix; i is the identifier of the first RRU, and the first RRU is the RRU where the one antenna is located; r is the identifier of the second RRU, and the second RRU is the RRU where any one of the M - 1 calibration antennas is located; j1 is the identifier of the one antenna; m1 is the identifier of the calibration antenna in the second RRU; k is the identifier of the resource block in the system bandwidth; Q is the number of resource blocks in the system bandwidth.

[0081] In one implementation, for any one of the calibration factors between the initial RRU, the processor is specifically configured to perform the following operations:

[0082] Determine the calibration factor between the RRU through the following formula:

[0083]

[0084] where, is the calibration factor between the RRU, and c r→i (k) is the calibration factor between the initial RRU.

[0085] In one implementation, the processor is specifically configured to perform the following operations:

[0086] Obtain the calibration factor within each RRU;

[0087] Determine the final calibration factor of each RRU according to the calibration factor within each RRU and the calibration factors between the M - 1 RRU;

[0088] For any one RRU, perform calibration processing on the RRU according to the final calibration factor of the RRU.

[0089] In one implementation, the processor is specifically configured to perform the following operations:

[0090] Use the in-RRU calibration factor of the first RRU as the final calibration factor of the first RRU, and use the product of the in-RRU calibration factor of the second RRU and the between-RRU calibration factor corresponding to the second RRU as the final calibration factor of the second RRU;

[0091] Wherein, the first RRU is the RRU where the one antenna is located, and the second RRU is the RRU where any one of the M-1 calibration antennas is located.

[0092] In an implementation manner, if the calibration antenna in the second RRU is not the reference antenna used by the second RRU during internal calibration, the processor is further configured to perform the following operations:

[0093] Correct the final calibration factor of the second RRU through the following formula:

[0094]

[0095] Wherein, is the corrected final calibration factor of the second RRU, is the final calibration factor of the second RRU, is the calibration factor of the calibration antenna in the second RRU, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

[0096] In an implementation manner, the processor is specifically configured to perform the following operations:

[0097] Among the N antennas of each RRU, use the reference antenna used by the RRU during internal calibration as the calibration antenna.

[0098] In an implementation manner, the processor is specifically configured to perform the following operations:

[0099] For the first RRU, among the N antennas of the first RRU, use the reference antenna used by the first RRU during internal calibration as the calibration antenna, the first RRU is any one of the M RRUs, and the one antenna is the calibration antenna in the first RRU;

[0100] For the second RRU, among the N antennas of the second RRU, use the antenna whose received quality of the first calibration sequence is greater than or equal to the preset threshold as the calibration antenna, the second RRU is any one of the M RRUs except the first RRU, and the first calibration sequence is sent by the calibration antenna of the first RRU.

[0101] In an implementation manner, for any one RRU, the processor is further configured to perform the following operations:

[0102] Determine one antenna among the N antennas as a reference antenna;

[0103] Transmit the first calibration sequence through the reference antenna, and receive and process it through the other N - 1 antennas among the N antennas except the reference antenna, to obtain N - 1 fourth calibration sequences;

[0104] Transmit the first calibration sequence through the N - 1 antennas, and receive and process it through the reference antenna, to obtain N - 1 fifth calibration sequences;

[0105] Determine the in - RRU calibration factor of the RRU according to the N - 1 fourth calibration sequences and the N - 1 fifth calibration sequences.

[0106] In one implementation, the processor is specifically configured to perform the following operations:

[0107] Determine N - 1 third channel matrices according to the N - 1 fourth calibration sequences;

[0108] Determine N - 1 fourth channel matrices according to the N - 1 fifth calibration sequences;

[0109] Determine N - 1 antenna calibration factors according to the N - 1 third channel matrices and the N - 1 fourth channel matrices;

[0110] Process the calibration factor of the reference antenna and the N - 1 antenna calibration factors to obtain the in - RRU calibration factor of the RRU.

[0111] In one implementation, the processor is specifically configured to perform the following operations:

[0112] For any one of the third channel matrices, determine an initial antenna calibration factor according to the third channel matrix and the fourth channel matrix corresponding to the third channel matrix;

[0113] Determine the N - 1 antenna calibration factors according to the N - 1 initial antenna calibration factors.

[0114] In one implementation, the processor is specifically configured to perform the following operations:

[0115] Determine the initial antenna calibration factor through the following formula:

[0116]

[0117] where c m2 (k) is the initial antenna calibration factor, is the third channel matrix, is the fourth channel matrix, j2 is the identifier of the reference antenna; m2 is the identifier of any one of the N - 1 antennas, and k is the identifier of a resource block in the system bandwidth; Q is the number of resource blocks in the system bandwidth.

[0118] In one embodiment, for any initial antenna calibration factor, the processor is specifically configured to perform the following operations:

[0119] Determine the antenna calibration factor through the following formula:

[0120]

[0121] where is the antenna calibration factor, and c m2 (k) is the initial antenna calibration factor.

[0122] In a third aspect, an embodiment of the present application provides a calibration device between RRUs, which is applied to a network device. M RRUs are provided on the network device, and N antennas are provided on each RRU. M is a positive integer greater than 1, and N is a positive integer greater than 1. The device includes:

[0123] A first determination unit, configured to determine a calibration antenna among the N antennas of each RRU;

[0124] A first transceiver unit, configured to send a first calibration sequence through one of the M calibration antennas, and receive and process through the other M - 1 calibration antennas among the M calibration antennas to obtain M - 1 second calibration sequences;

[0125] A second transceiver unit, configured to send the first calibration sequence through the M - 1 calibration antennas, and receive and process through the one antenna to obtain M - 1 third calibration sequences;

[0126] A first calibration processing unit, configured to perform calibration processing on the M RRUs according to the M - 1 second calibration sequences and the M - 1 third calibration sequences.

[0127] In one embodiment, the first calibration processing unit is specifically configured to:

[0128] Determine M - 1 first channel matrices according to the M - 1 second calibration sequences;

[0129] Determine M - 1 second channel matrices according to the M - 1 third calibration sequences;

[0130] Determine M - 1 calibration factors between RRUs according to the M - 1 first channel matrices and the M - 1 second channel matrices;

[0131] Calibrate the M RRU according to the calibration factors between the M-1 RRU.

[0132] In one embodiment, the first calibration processing unit is specifically configured to:

[0133] For any one of the first channel matrices, determine the initial calibration factors between the RRU according to the first channel matrix and the second channel matrix corresponding to the first channel matrix;

[0134] Determine the calibration factors between the M-1 RRU according to the M-1 initial calibration factors between the RRU.

[0135] In one embodiment, the first calibration processing unit is specifically configured to:

[0136] Determine the initial calibration factors between the RRU through the following formula:

[0137]

[0138] where c r→i (k) is the initial calibration factor between the RRU; is the first channel matrix; is the second channel matrix; i is the identifier of the first RRU, and the first RRU is the RRU where the one antenna is located; r is the identifier of the second RRU, and the second RRU is the RRU where any one of the M-1 calibration antennas is located; j1 is the identifier of the one antenna; m1 is the identifier of the calibration antenna in the second RRU; k is the identifier of the resource block in the system bandwidth; Q is the number of resource blocks in the system bandwidth.

[0139] In one embodiment, for any one of the initial calibration factors between the RRU, the first calibration processing unit is specifically configured to:

[0140] Determine the calibration factors between the RRU through the following formula:

[0141]

[0142] where is the calibration factor between the RRU; c r→i (k) is the initial calibration factor between the RRU.

[0143] In one embodiment, the first calibration processing unit is specifically configured to:

[0144] Obtain the calibration factors within each RRU;

[0145] Determine the final calibration factor of each RRU according to the in-RRU calibration factor of each RRU and the between-RRU calibration factors of the M-1 RRUs;

[0146] For any one RRU, perform calibration processing on the RRU according to the final calibration factor of the RRU.

[0147] In one implementation manner, the first calibration processing unit is specifically configured to:

[0148] Use the in-RRU calibration factor of the first RRU as the final calibration factor of the first RRU, and use the product of the in-RRU calibration factor of the second RRU and the between-RRU calibration factor corresponding to the second RRU as the final calibration factor of the second RRU;

[0149] Wherein, the first RRU is the RRU where the one antenna is located, and the second RRU is the RRU where any one of the M-1 calibration antennas is located.

[0150] In one implementation manner, if the calibration antenna in the second RRU is not the reference antenna used by the second RRU during internal calibration, the device further includes:

[0151] A correction unit, configured to correct the final calibration factor of the second RRU through the following formula:

[0152]

[0153] Wherein, is the corrected final calibration factor of the second RRU, is the final calibration factor of the second RRU, is the calibration factor of the calibration antenna in the second RRU, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

[0154] In one implementation manner, the first determination unit is specifically configured to:

[0155] Among the N antennas of each RRU, use the reference antenna used by the RRU during internal calibration as the calibration antenna.

[0156] In one implementation manner, the first determination unit is specifically configured to:

[0157] For the first RRU, among the N antennas of the first RRU, use the reference antenna used by the first RRU during internal calibration as the calibration antenna, the first RRU is any one of the M RRUs, and the one antenna is the calibration antenna in the first RRU;

[0158] For the second RRU, among the N antennas of the second RRU, the antennas with the reception quality of the first calibration sequence being greater than or equal to a preset threshold are used as calibration antennas, where the second RRU is any one of the M RRUs other than the first RRU, and the first calibration sequence is sent by the calibration antennas of the first RRU.

[0159] In one implementation, for any one RRU, the apparatus further includes:

[0160] A second determination unit, configured to determine one antenna as a reference antenna among the N antennas;

[0161] A third transceiver unit, configured to send the first calibration sequence through the reference antenna, and receive and process through the other N - 1 antennas among the N antennas except the reference antenna to obtain N - 1 fourth calibration sequences;

[0162] A fourth transceiver unit, configured to send the first calibration sequence through the N - 1 antennas, and receive and process through the reference antenna to obtain N - 1 fifth calibration sequences;

[0163] A second calibration processing unit, configured to determine the in - RRU calibration factor of the RRU according to the N - 1 fourth calibration sequences and the N - 1 fifth calibration sequences.

[0164] In one implementation, the second calibration processing unit is specifically configured to:

[0165] Determine N - 1 third channel matrices according to the N - 1 fourth calibration sequences;

[0166] Determine N - 1 fourth channel matrices according to the N - 1 fifth calibration sequences;

[0167] Determine N - 1 antenna calibration factors according to the N - 1 third channel matrices and the N - 1 fourth channel matrices;

[0168] Process the calibration factor of the reference antenna and the N - 1 antenna calibration factors to obtain the in - RRU calibration factor of the RRU.

[0169] In one implementation, the second calibration processing unit is specifically configured to:

[0170] For any one of the third channel matrices, determine an initial antenna calibration factor according to the third channel matrix and the fourth channel matrix corresponding to the third channel matrix;

[0171] Determine the N - 1 antenna calibration factors according to the N - 1 initial antenna calibration factors.

[0172] In one embodiment, the second calibration processing unit is specifically configured to:

[0173] Determine the initial antenna calibration factor through the following formula:

[0174]

[0175] where c m2 (k) is the initial antenna calibration factor, is the third channel matrix, is the fourth channel matrix, j2 is the identifier of the reference antenna; m2 is the identifier of any one of the N-1 antennas, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

[0176] In one embodiment, for any initial antenna calibration factor, the second calibration processing unit is specifically configured to:

[0177] Determine the antenna calibration factor through the following formula:

[0178]

[0179] where is the antenna calibration factor, and c m2 (k) is the initial antenna calibration factor.

[0180] In a fourth aspect, an embodiment of the present application provides a processor-readable storage medium, where the processor-readable storage medium stores a computer program, and the computer program is used to cause the processor to execute the method described in the first aspect.

[0181] The present application provides a calibration method, device, and storage medium for RRU. In this method, one calibration antenna is determined among the N antennas of each RRU; a first calibration sequence is sent through one of the M calibration antennas, and the other M-1 calibration antennas among the M calibration antennas are used for receiving and processing to obtain M-1 second calibration sequences; the first calibration sequence is sent through the M-1 calibration antennas, and one antenna is used for receiving and processing to obtain M-1 third calibration sequences; the M RRUs are calibrated according to the M-1 second calibration sequences and the M-1 third calibration sequences. By performing one round of calibration through one calibration antenna in each RRU, the calibration of all RRUs can be completed, reducing the overhead of RRU calibration calculation.

[0182] It should be understood that the content described in the above Summary of the Invention section is not intended to limit the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understandable through the following description. Brief Description of the Drawings

[0183] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0184] Figure 1 Schematic diagram for modeling the reciprocity error of the uplink and downlink channels in the related art;

[0185] Figure 2 Schematic diagram for mutual transmission of calibration sequences between internal antennas of a PICO RRU in the related art;

[0186] Figure 3 Schematic diagram for mapping of calibration sequences in the case of multiple transmit and single receive in the related art;

[0187] Figure 4 Schematic diagram for mutual transmission of calibration sequences between RRUs in the related art;

[0188] Figure 5 Flowchart of a calibration method between RRUs provided by an embodiment of the present application;

[0189] Figure 6 Flowchart of another calibration method between RRUs provided by an embodiment of the present application;

[0190] Figure 7 Flowchart of a method for determining calibration factors within an RRU provided by an embodiment of the present application;

[0191] Figure 8 Schematic diagram for mutual transmission between two antennas provided by an embodiment of the present application;

[0192] Figure 9 Schematic diagram of the structure of a calibration device between RRUs provided by an embodiment of the present application;

[0193] Figure 10 Schematic diagram of the structure of another calibration device between RRUs provided by an embodiment of the present application;

[0194] Figure 11 Schematic diagram of the structure of yet another calibration device between RRUs provided by an embodiment of the present application. Detailed Description of the Embodiments

[0195] In the embodiments of the present invention, the term "and / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0196] In the embodiments of the present application, the term "a plurality of" refers to two or more, and other quantifiers are similar.

[0197] In the embodiments of the present application, descriptions such as "first" and "second" are only used for indication and to distinguish the described objects, without an order, and do not represent a special limitation on the number of objects in the embodiments of the present application, and cannot constitute any limitation to the embodiments of the present application. For example, the first calibration sequence is the time-frequency sequence before transmission, and the second calibration sequence is the frequency-domain sequence after reception. The descriptions such as "first" and "second" are only used to distinguish different forms of calibration sequences, rather than indicating differences in the size, priority, or importance of these two calibration sequences.

[0198] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0199] The embodiments of the present application provide a calibration method, device, and storage medium between RRUs to reduce the overhead of RRU calibration calculation.

[0200] Among them, the method and the device are based on the same inventive concept. Since the principles of the method and the device for solving problems are similar, the implementation of the device and the method can be referred to each other, and the repeated parts will not be elaborated.

[0201] The technical solutions provided by the embodiments of the present application can be applicable to various systems, especially 5G systems. For example, the applicable systems can be Global System of Mobile Communication (GSM) systems, Code Division Multiple Access (CDMA) systems, Wideband Code Division Multiple Access (WCDMA) General Packet Radio Service (GPRS) systems, Long Term Evolution (LTE) systems, LTE Frequency Division Duplex (FDD) systems, LTE Time Division Duplex (TDD) systems, Long Term Evolution Advanced (LTE-A) systems, Universal Mobile Telecommunications System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX) systems, 5G New Radio (NR) systems, etc. Both terminals and network devices are included in these various systems. The system may also include a core network part, such as an Evolved Packet System (EPS), 5G System (5GS), etc.

[0202] The network device involved in the embodiments of this application can be a base station, which may include multiple cells that provide services to terminals. Depending on the specific application scenarios, the base station can also be referred to as an access point, or it can be a device in the access network that communicates with wireless terminals through one or more sectors over the air interface, or other names. The network device can be used to mutually replace the received air frames and Internet Protocol (IP) packets, and act as a router between the wireless terminal and the rest of the access network, where the rest of the access network may include an Internet Protocol (IP) communication network. The network device can also coordinate the management of the attributes of the air interface. For example, the network device involved in the embodiments of this application can be a network device (base transceiver station, BTS) in a Global System for Mobile Communications (GSM) or Code Division Multiple Access (CDMA), or it can be a network device (NodeB) in a Wide-band Code Division Multiple Access (WCDMA), or it can also be an evolved network device (evolutional Node B, eNB or e-NodeB) in a Long Term Evolution (LTE) system, a 5G base station (gNB) in a 5G network architecture (next generation system), or it can be a Home Evolved Node B (HeNB), a relay node, a femto, a pico, etc. The embodiments of this application do not limit this. In some network architectures, the network device can include a centralized unit (CU) node and a distributed unit (DU) node, and the centralized unit and the distributed unit can also be arranged separately geographically.

[0203] For the convenience of understanding, the related technologies involved in the embodiments of this application are described below.

[0204] In the indoor distribution application scenario of time division duplexing (TDD), for a single Remote Radio Unit (RRU), non-codebook beamforming can be theoretically achieved. In order to reduce costs, the indoor distribution RRU does not have a calibration network designed inside, and antenna calibration cannot be realized. The up / downlink channel characteristics are not aligned, and there may be significant differences between channels, resulting in a significant reduction in performance and even negative gain. In addition, the characteristic differences between channels are also not conducive to codebook beamforming, and the performance of codebook beamforming will be affected. For multiple RRUs, system performance can be theoretically improved through joint beamforming, which also requires the up / downlink channel characteristics of each antenna on multiple RRUs to be aligned. Alignment means unifying the ratio of the uplink channel frequency response to the downlink channel frequency response of each antenna, that is, if the ratio of the uplink channel frequency response to the downlink channel frequency response of each antenna is the same, it means that the up / downlink channel characteristics of each antenna are aligned.

[0205] Figure 1 Illustrates the modeling of reciprocity error in the uplink and downlink channels in a TDD system, as Figure 1 shown, H AI,DL is the downlink air interface channel frequency response, H AI,UL is the uplink air interface channel frequency response, H bt is the network device transmit channel frequency response, H br is the network device receive channel frequency response, H mt is the terminal transmit channel frequency response, H mr is the terminal receive channel frequency response.

[0206] Among them, the composite channel frequency response H DL from the network device to the terminal receive can be expressed as:

[0207] H DL = H mr H AI,DL H bt

[0208] The composite channel frequency response H UL from the terminal to the network device receive can be expressed as:

[0209] H UL = H br H AI,UL H mt

[0210] For simplicity, there are usually two assumptions:

[0211] 1) The time delays of the uplink and downlink are very small and within the coherence time, and there is

[0212] 2) The coupling between antennas is not considered, so the response of the radio frequency (RF) circuit (Hmr , H br , H mt , H bt ) can be considered as diagonal matrices. That is, H br = diag(h br,1 , h br,2 , …, h br,X1 ), where X1 is the number of antennas set on the network device, and h br,1 represents the receiving channel frequency response of the first antenna on the network device, and h br,2 represents the receiving channel frequency response of the second antenna on the network device, and h br,X1 represents the receiving channel frequency response of the X1-th antenna on the network device.

[0213] Define the reciprocity error E m on the terminal side as:

[0214]

[0215] where X2 is the number of antennas set on the terminal, and e m,1 represents the reciprocity error of the first antenna on the terminal side, and e m,2 represents the reciprocity error of the second antenna on the terminal side, and e m,X2 represents the reciprocity error of the X2-th antenna on the terminal side.

[0216] Define the reciprocity error E b on the network device side as:

[0217]

[0218] where X1 is the number of antennas set on the network device, and e b,1 represents the reciprocity error of the first antenna on the network device side, and e b,2 represents the reciprocity error of the second antenna on the network device side, and e b,X1 represents the reciprocity error of the X1-th antenna on the network device side.

[0219] Then the relationship between the uplink channel and the downlink channel can be expressed as:

[0220]

[0221] In the related art, for the single RRU scenario, usually the internal antennas of the RRU are used for short-distance radiation for self-calibration; for the multi-RRU scenario, usually the air interface wireless propagation channel between RRUs is used for self-calibration; there is no need to use a calibration loopback network and the feedback of the terminal.

[0222] For the single RRU scenario, taking a 4-antenna pico base station (PICO RRU) as an example, the schematic diagram of the near-distance mutual transmission of the calibration sequence between internal antennas is asFigure 2 As shown in the figure, the calibration process is as follows:

[0223] First round of calibration: Select antenna 1 as the reference antenna. Antennas 2, 3, and 4 first perform the mapping of the calibration sequence respectively. As Figure 3 shown, the calibration sequences of different antennas are mapped to different resource element (RE) positions respectively; then the mapped calibration sequences are sent to antenna 1 respectively. After receiving the calibration sequences, antenna 1 performs channel estimation based on the calibration sequence before transmission and the received calibration sequence to obtain the channel estimation matrix where DL represents that other antennas send calibration sequences to the reference antenna, m2 is the antenna number (which can also be called the antenna identifier), Q is the number of resource blocks (RB) included in the system bandwidth, and is also the length of the calibration sequence. Antenna 1 performs the mapping of the calibration sequence and sends the mapped calibration sequence to antennas 2, 3, and 4. After receiving the calibration sequences, antennas 2, 3, and 4 perform channel estimation respectively based on the calibration sequence before transmission and the received calibration sequence to obtain the channel estimation matrix where UL represents that the reference antenna sends calibration sequences to other antennas. According to calculate the calibration factor for the first round of calibration

[0224] Second round of calibration: Select antenna 4 as the reference antenna. Antennas 1, 2, and 3 first perform the mapping of the calibration sequence respectively. The calibration sequences of different antennas are mapped to different RE positions respectively; then the mapped calibration sequences are sent to antenna 4 respectively. After receiving the calibration sequences, antenna 4 performs channel estimation based on the calibration sequence before transmission and the received calibration sequence to obtain the channel estimation matrix where DL represents that other antennas send calibration sequences to the reference antenna, m2 is the antenna number (which can also be called the antenna identifier), Q is the number of RBs included in the system bandwidth, and is also the length of the calibration sequence. Then antenna 4 performs the mapping of the calibration sequence and sends the mapped calibration sequence to antennas 1, 2, and 3. After receiving the calibration sequences, antennas 1, 2, and 3 perform channel estimation respectively based on the calibration sequence before transmission and the received calibration sequence to obtain the channel estimation matrix where UL represents that the reference antenna sends calibration sequences to other antennas. According to and calculate the calibration factor for the second round of calibration

[0225] Combine the calibration factors of the two rounds to obtain the calibration factors of the four antennas; then interpolate the calibration factors of the four antennas to obtain the calibration factors at the RE level of the four antennas. Compensate the frequency-domain transmission data of the four antennas according to the calibration factors at the RE level of the four antennas to obtain the calibrated and compensated transmission data, thus completing the calibration.

[0226] For the multi-RRU scenario, taking 3 RRUs with 4 antennas per RRU as an example, the schematic diagram of the near-distance mutual transmission of the calibration sequences between RRUs is as Figure 4 shown, and the calibration process is as follows:

[0227] First-round calibration: Select antenna 1 of RRU1 as the reference antenna to calibrate the receive / transmit channel characteristics of the antennas of RRU2 and RRU3. First, antenna 1 of RRU1 sends the calibration sequence, and the antennas to be calibrated of RRU2 and RRU3 receive the calibration sequence (as shown by the solid line in Figure 4 ). After the antennas to be calibrated of RRU2 and RRU3 receive the calibration sequence, they perform channel estimation respectively according to the calibration sequence before transmission and the received calibration sequence to obtain the channel estimation matrix where UL represents the reference antenna sending the calibration sequence to other antennas, r is the number of the RRU (which can also be called the identifier of the RRU), and n is the number of the antenna (which can also be called the identifier of the antenna). Then, the antennas to be calibrated of RRU2 and RRU3 send the calibration sequence, and antenna 1 in RRU1 receives the calibration sequence (as shown by the dashed line in Figure 4 ). After antenna 1 in RRU1 receives the calibration sequence, it performs channel estimation according to the calibration sequence before transmission and the received calibration sequence to obtain the channel estimation matrix where DL represents other antennas sending the calibration sequence to the reference antenna. Calculate the first-round calibration factors according to and to obtain

[0228] Second-round calibration: Select antenna 1 of RRU2 as the reference antenna to calibrate the receive / transmit channel characteristics of the antennas of RRU1 and RRU3. First, antenna 1 of RRU2 sends the calibration sequence, and the antennas to be calibrated of RRU1 and RRU3 receive the calibration sequence (as shown by the dash-dotted line in Figure 4 ). After the antennas to be calibrated of RRU1 and RRU3 receive the calibration sequence, they perform channel estimation respectively according to the calibration sequence before transmission and the received calibration sequence to obtain the channel estimation matrix Among them, UL means that the reference antenna sends a calibration sequence to other antennas, r is the number of the RRU (which can also be called the identifier of the RRU), and n is the number of the antenna (which can also be called the identifier of the antenna). Then, the antennas to be calibrated of RRU1 and RRU3 send calibration sequences, and antenna 1 in RRU2 receives the calibration sequence (as shown by the dotted line in Figure 4 After antenna 1 in RRU2 receives the calibration sequence, it performs channel estimation based on the calibration sequence before transmission and the received calibration sequence to obtain the channel estimation matrix Among them, DL means that other antennas send a calibration sequence to the reference antenna. According to and the second-round calibration factor is calculated

[0229] The calibration factors of two rounds are combined to obtain the calibration factors of each antenna on multiple RRUs. Then, interpolation is performed on the calibration factors to obtain the calibration factors at the RE level.

[0230] The above calibration scheme has the following problems:

[0231] (1) For the single-RRU scenario, the calculation of the calibration factor in each round can only align the other 3 antennas except the reference antenna (that is, unify the ratio of the uplink channel frequency response to the downlink channel frequency response of the other 3 antennas except the reference antenna), and there is a problem that one antenna in the RRU antenna array cannot be calibrated. For example, in the above example, in the first-round calibration, the calibration factor of antenna 1 is 0, that is, antenna 1 is not calibrated; in the second-round calibration, the calibration factor of antenna 4 is zero, that is, antenna 4 is not calibrated. Therefore, different reference antennas need to be selected to calculate the calibration factors of two rounds, resulting in a large calculation overhead for the RRU; in addition, the calculation of one more round of calibration factors also places more stringent timing requirements on the RRU calibration calculation process; it can be seen from the calculation process of the calibration factors that the existing technical solutions cannot perform self-calibration through the air interface radiation method for 2-channel RRUs and need to rely on other means.

[0232] (2) For the multi-RRU scenario, if the RRU where the reference antenna is located is called the reference RRU, then in each round of calibration, only the other RRUs except the reference RRU can be aligned (that is, the ratio of the uplink channel frequency response to the downlink channel frequency response of all antennas in the other RRUs except the reference RRU is unified). There is also a problem that one RRU cannot be calibrated. Therefore, different reference RRUs need to be selected to calculate the calibration factors in two rounds, resulting in a large calculation overhead for the RRU. Or, an additional RRU is introduced for auxiliary calibration, that is, this additional RRU is used as the reference RRU, but it will affect the universality of the entire solution and increase the deployment cost. In addition, it can be seen from the calculation process of the calibration factor that in the multi-RRU scenario, at least 3 RRUs that can mutually transmit and receive calibration sequences are required to complete the calibration of multiple RRUs, which requires a high deployment environment for the RRUs.

[0233] Based on the problems in the prior art, the present application proposes the following technical concept: Without increasing the hardware cost, taking the RRU where one antenna is located as the reference, align the M - 1 RRUs to the RRU where one antenna is located (that is, adjust the ratio of the uplink channel frequency response to the downlink channel frequency response of all antennas in the M - 1 RRUs to the ratio of the uplink channel frequency response to the downlink channel frequency response of the antenna in the RRU where one antenna is located), that is, the calibration of all RRUs can be completed through one round of calibration, reducing the calculation overhead of RRU calibration.

[0234] The following introduces the calibration method between RRUs provided by the present application in combination with specific embodiments.

[0235] Figure 5 It is a flowchart of a calibration method between RRUs provided by an embodiment of the present application. As Figure 5 shown, the method includes:

[0236] S501. Determine one calibration antenna among the N antennas of each RRU.

[0237] The execution subject of the embodiment of the present application can be a network device or a calibration device set in the network device. The calibration device can be implemented by software or by a combination of software and hardware.

[0238] There are M RRUs set on the network device, and N antennas are set on each RRU. M is a positive integer greater than 1, and N is a positive integer greater than 1.

[0239] It should be noted that the number of antennas N of each RRU among the M RRUs can be the same or different.

[0240] For example, if there are 3 RRU, namely RRU1, RRU2, and RRU3, then RRU1 can have 2 antennas, RRU2 can have 4 antennas, and RRU4 can have 4 antennas.

[0241] It should be noted that when performing calibration between RRU, each RRU on the network device has completed internal calibration, that is, all antennas within each RRU have been calibrated.

[0242] In a possible implementation, one calibration antenna can be determined from the N antennas of each RRU in the following manner:

[0243] Among the N antennas of each RRU, use the reference antenna used by the RRU during internal calibration as the calibration antenna.

[0244] Exemplarily, if there are 3 RRU, namely RRU1, RRU2, and RRU3, and all 3 RRU are provided with 4 antennas. Among them, RRU1 uses antenna 1 as the reference antenna during internal calibration, RRU2 uses antenna 1 as the reference antenna during internal calibration, and RRU3 uses antenna 1 as the reference antenna during internal calibration. Then, when performing RRU calibration, antenna 1 in RRU1 can be used as the calibration antenna of RRU1, antenna 1 in RRU2 can be used as the calibration antenna of RRU2, and antenna 1 in RRU3 can be used as the calibration antenna of RRU3.

[0245] In a possible implementation, one calibration antenna can be determined from the N antennas of each RRU in the following manner:

[0246] For the first RRU, among the N antennas of the first RRU, use the reference antenna used by the first RRU during internal calibration as the calibration antenna. The first RRU is any one of the M RRU, and one antenna is the calibration antenna in the first RRU; for the second RRU, among the N antennas of the second RRU, use the antenna whose reception quality of the first calibration sequence is greater than or equal to the preset threshold as the calibration antenna. The second RRU is any one of the M RRU other than the first RRU, and the first calibration sequence is sent by the calibration antenna of the first RRU.

[0247] The first RRU is the reference RRU during RRU calibration, and one antenna is the reference antenna during RRU calibration.

[0248] The preset threshold can be determined according to the actual situation, and this application does not limit it.

[0249] The reception quality of the first calibration sequence can be characterized by any one of the following parameters: signal to interference plus noise ratio (SINR), reference signal receiving power (RSRP), received signal strength indication (RSSI).

[0250] The antenna corresponding to the maximum value among the reception qualities of the N first calibration sequences of the second RRU can also be determined as the calibration antenna.

[0251] Exemplarily, if there are 3 RRUs, namely RRU1, RRU2, and RRU3, and each of the 3 RRUs is provided with 4 antennas. Among them, RRU1 uses antenna 1 as the reference antenna during internal calibration. Arbitrarily determine one RRU among the 3 RRUs as the first RRU. For example, if RRU1 is taken as the first RRU, then antenna 1 of RRU1 is used as the calibration antenna of RRU1; the first calibration sequence is sent by the calibration antenna of RRU1, and the 4 antennas of RRU2 and the 4 antennas of RRU3 receive the first calibration sequence; if the reception quality of the first calibration sequence of antenna 2 among the 4 antennas of RRU2 is the highest, then antenna 2 of RRU2 can be determined as the calibration antenna of RRU2; if the reception quality of the first calibration sequence of antenna 3 among the 4 antennas of RRU3 is the highest, then antenna 3 of RRU3 can be determined as the calibration antenna of RRU3.

[0252] Selecting an antenna with better reception quality of the calibration sequence for inter-RRU calibration can improve the accuracy of RRU calibration.

[0253] S502: Send the first calibration sequence through one of the M calibration antennas, and receive and process through the other M - 1 calibration antennas among the M calibration antennas to obtain M - 1 second calibration sequences.

[0254] The first calibration sequence can be a time-domain sequence.

[0255] The second calibration sequence can be a frequency-domain sequence.

[0256] After receiving the first calibration sequence, the M - 1 calibration antennas can perform time-frequency transformation, demapping, etc. on the first calibration sequence to obtain the second calibration sequence. It should be noted that other processing can also be included, such as cyclic prefix (CP) removal, virtual subcarrier removal, etc. The specific processing operations are not limited in this application.

[0257] Exemplarily, if there are a total of 3 RRUs, namely RRU1, RRU2, and RRU3, and each RRU has 4 antennas. Among them, the calibration antenna of RRU1 is antenna 1, the calibration antenna of RRU2 is antenna 2, and the calibration antenna of RRU3 is antenna 3. The first calibration sequence can be sent through antenna 1 in RRU1, and the first calibration sequence can be received and processed through antenna 2 in RRU2 and antenna 3 in RRU3 to obtain two second calibration sequences.

[0258] S503: Send the first calibration sequence through M - 1 calibration antennas, and receive and process it through one antenna to obtain M - 1 third calibration sequences.

[0259] The third calibration sequence can be a frequency-domain sequence.

[0260] The initial calibration sequence can be frequency-domain mapped and time-frequency converted in the form of frequency-division multiplexing to obtain the first calibration sequence; or the first calibration sequence can be sent on different symbols in the form of time-division multiplexing.

[0261] After receiving the first calibration sequence, one calibration antenna can process the first calibration sequence to obtain the third calibration sequence. For the specific processing operations, reference can be made to the relevant descriptions in S502, which will not be elaborated here.

[0262] Exemplarily, if there are a total of 3 RRUs, namely RRU1, RRU2, and RRU3, and each RRU has 4 antennas. Among them, the calibration antenna of RRU1 is antenna 1, the calibration antenna of RRU2 is antenna 2, and the calibration antenna of RRU3 is antenna 3. The first calibration sequence can be sent through antenna 2 in RRU2 and antenna 3 in RRU3 respectively, and the first calibration sequence can be received and processed through antenna 1 in RRU1 to obtain two third calibration sequences.

[0263] S504: Calibrate the M RRUs according to the M - 1 second calibration sequences and the M - 1 third calibration sequences.

[0264] In a possible implementation, the M RRUs can be calibrated in the following manner:

[0265] The calibration factors between M - 1 RRUs can be determined according to the M - 1 second calibration sequences and the M - 1 third calibration sequences; the final calibration factor of each RRU can be determined according to the calibration factors between M - 1 RRUs and the intra-RRU calibration factor of each RRU; for any one RRU, the RRU is calibrated according to the final calibration factor of the RRU.

[0266] Performing calibration processing on the RRU means that the RRU can be calibrated by the final calibration factor of the RRU. The final calibration factor of the RRU may include the calibration factors of each antenna in the RRU. The frequency-domain transmission data on the corresponding antenna can be compensated by the calibration factors of each antenna in the RRU, and thus the calibration of the RRU can be completed.

[0267] In Figure 5 In the illustrated embodiment, one calibration antenna is determined among the N antennas of each RRU; a first calibration sequence is sent through one of the M calibration antennas, and the other M - 1 calibration antennas among the M calibration antennas are used for receiving and processing to obtain M - 1 second calibration sequences; the first calibration sequence is sent through the M - 1 calibration antennas, and one antenna is used for receiving and processing to obtain M - 1 third calibration sequences; the M RRUs are calibrated according to the M - 1 second calibration sequences and the M - 1 third calibration sequences. Calibration of all RRUs can be completed by performing one round of calibration through one calibration antenna in each RRU, reducing the overhead of RRU calibration calculation; in addition, the solution provided in the embodiment of the present application supports the deployment scenario of two RRUs; furthermore, in the case of adding RRUs, only the newly added RRU needs to be calibrated with any one of the currently calibrated RRUs, without the participation of all the calibrated RRUs. That is, the solution provided in the embodiment of the present application can better handle the situation where the RRU deployment changes.

[0268] In Figure 5 Based on the illustrated embodiment, below, in combination with Figure 6 the calibration method of the present application will be described in detail.

[0269] Figure 6 is a flowchart of another calibration method between RRUs provided in the embodiment of the present application. As Figure 6 shown, the method includes:

[0270] S601. Determine one calibration antenna among the N antennas of each RRU.

[0271] S602. Send a first calibration sequence through one of the M calibration antennas, and receive and process through the other M - 1 calibration antennas among the M calibration antennas to obtain M - 1 second calibration sequences.

[0272] S603. Send the first calibration sequence through the M - 1 calibration antennas, and receive and process through one antenna to obtain M - 1 third calibration sequences.

[0273] It should be noted that the execution processes of S601 to S603 can refer to the execution processes of S501 to S503, which will not be elaborated here.

[0274] S604. Determine M - 1 first channel matrices according to M - 1 second calibration sequences.

[0275] In a possible implementation manner, M - 1 first channel matrices can be determined according to the initial calibration sequence corresponding to the first calibration sequence and M - 1 second calibration sequences.

[0276] Exemplarily, if there are a total of 3 RRUs, namely RRU1, RRU2, and RRU3, and each RRU has 4 antennas. Among them, the calibration antenna of RRU1 is antenna 1, the calibration antenna of RRU2 is antenna 2, and the calibration antenna of RRU3 is antenna 3. The first calibration sequence can be sent through antenna 1 in RRU1, and the first calibration sequence can be received and processed by antenna 2 in RRU2 and antenna 3 in RRU3 to obtain two second calibration sequences; two first channel matrices can be determined according to the initial calibration sequence corresponding to the first calibration sequence and the two second calibration sequences.

[0277] The minimum mean squared error (MMSE) criterion can be used for channel estimation to determine the channel matrix, or other methods can also be used to determine the channel matrix.

[0278] S605. Determine M - 1 second channel matrices according to M - 1 third calibration sequences.

[0279] In a possible implementation manner, M - 1 second channel matrices can be determined according to the initial calibration sequence corresponding to the first calibration sequence and M - 1 third calibration sequences.

[0280] Exemplarily, if there are a total of 3 RRUs, namely RRU1, RRU2, and RRU3, and each RRU has 4 antennas. Among them, the calibration antenna of RRU1 is antenna 1, the calibration antenna of RRU2 is antenna 2, and the calibration antenna of RRU3 is antenna 3. The first calibration sequence can be sent through antenna 2 in RRU2 and antenna 3 in RRU3 respectively, and the first calibration sequence can be received and processed by antenna 1 in RRU1 to obtain two third calibration sequences; two second channel matrices can be determined according to the initial calibration sequence corresponding to the first calibration sequence and the two third calibration sequences.

[0281] S606. Determine M - 1 calibration factors between RRUs according to M - 1 first channel matrices and M - 1 second channel matrices.

[0282] In a possible implementation manner, M - 1 calibration factors between RRUs can be determined by the following method:

[0283] For any first channel matrix, determine an initial calibration factor between RRU based on the first channel matrix and a second channel matrix corresponding to the first channel matrix; determine M-1 calibration factors between RRU based on the M-1 initial calibration factors between RRU.

[0284] The first channel matrix and the second channel matrix corresponding to the first channel matrix may be determined based on the same antenna pair.

[0285] Exemplarily, if a first calibration sequence is sent through antenna 1 of RRU1, and the first calibration sequence is received and processed through antenna 2 of RRU2 to obtain a second calibration sequence; if the first calibration sequence is sent through antenna 2 of RRU2, and the first calibration sequence is received and processed through antenna 1 of RRU1 to obtain a third calibration sequence; then the first channel matrix is determined based on the initial calibration sequence corresponding to the first calibration sequence and the second calibration sequence, and the second channel matrix corresponding to the first channel matrix is determined based on the initial calibration sequence corresponding to the first calibration sequence and the third calibration sequence.

[0286] In a possible implementation, the initial calibration factor between RRU may be determined by the following formula:

[0287]

[0288] where, c r→i (k) is the initial calibration factor between RRU; is the first channel matrix;

[0289] is the second channel matrix; i is the identifier of the first RRU, and the first RRU is the RRU where an antenna is located; r is the identifier of the second RRU, and the second RRU is the RRU where any one of the M-1 calibration antennas is located; j1 is the identifier of an antenna (i.e., the identifier of the reference antenna during calibration between RRU); m1 is the identifier of the calibration antenna in the second RRU; k is the identifier of the resource block in the system bandwidth; Q is the number of resource blocks in the system bandwidth.

[0290] In a possible implementation, for any initial calibration factor between RRU, the calibration factor between RRU may be determined by the following formula:

[0291]

[0292] where, is the calibration factor between RRU; c r→i (k) is the initial calibration factor between RRU; i is the identifier of the first RRU, and r is the identifier of the second RRU.

[0293] S607. Obtain the calibration factor within each RRU.

[0294] S608. Determine the final calibration factor for each RRU according to the in-RRU calibration factor of each RRU and the inter-RRU calibration factors of M - 1 RRUs.

[0295] In a possible implementation, the final calibration factor for each RRU can be determined in the following way:

[0296] Take the in-RRU calibration factor of the first RRU as the final calibration factor of the first RRU, and take the product of the in-RRU calibration factor of the second RRU and the inter-RRU calibration factor corresponding to the second RRU as the final calibration factor of the second RRU; where the first RRU is the RRU where one antenna is located, and the second RRU is the RRU where any one of the M - 1 calibration antennas is located.

[0297] Exemplarily, the final calibration factor of the second RRU can be determined by the following formula:

[0298]

[0299] Where, is the final calibration factor of the second RRU, is the in-RRU calibration factor of the second RRU, the inter-RRU calibration factor corresponding to the second RRU.

[0300] In a possible implementation, if the calibration antenna in the second RRU is not the reference antenna used by the second RRU during internal calibration, then on the basis of the above steps, the final calibration factor of the second RRU also needs to be corrected by the following formula:

[0301]

[0302] Where, is the corrected final calibration factor of the second RRU, is the final calibration factor of the second RRU, is the calibration factor of the calibration antenna in the second RRU, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

[0303] S609. For any RRU, perform calibration processing on the RRU according to the final calibration factor of the RRU.

[0304] It should be noted that the execution process of S609 can refer to the relevant execution process of S504, which will not be elaborated here.

[0305] In Figure 6In the illustrated embodiment, one calibration antenna is determined among the N antennas of each RRU; a first calibration sequence is transmitted through one of the M calibration antennas, and the other M - 1 calibration antennas among the M calibration antennas are used for receiving and processing to obtain M - 1 second calibration sequences; S603: the first calibration sequence is transmitted through the M - 1 calibration antennas, and one antenna is used for receiving and processing to obtain M - 1 third calibration sequences; M - 1 first channel matrices are determined according to the M - 1 second calibration sequences; M - 1 second channel matrices are determined according to the M - 1 third calibration sequences; M - 1 calibration factors between RRU are determined according to the M - 1 first channel matrices and the M - 1 second channel matrices; the in - RRU calibration factors of each RRU are obtained; the final calibration factors of each RRU are determined according to the in - RRU calibration factors of each RRU and the M - 1 calibration factors between RRU; for any one RRU, the RRU is calibrated according to the final calibration factor of the RRU. On the basis that each RRU has completed in - calibration, taking the RRU where one antenna is located as a reference, the M - 1 RRUs are aligned with the RRU where one antenna is located, that is, all RRUs can be calibrated through one - round calibration, reducing the overhead of RRU calibration calculation; in addition, the solution provided by the embodiment of the present application supports the deployment scenario of two RRUs; furthermore, in the case of adding RRUs, only the newly added RRU needs to be calibrated with any one of the currently calibrated RRUs, without the participation of all the calibrated RRUs, that is, the solution provided by the embodiment of the present application can better cope with the situation where the RRU deployment changes.

[0306] The above - mentioned embodiment is the inter - RRU calibration carried out on the basis that each RRU has completed in - calibration. Next, in combination with Figure 7 it is described in detail how to determine the in - RRU calibration factors used during the in - RRU calibration.

[0307] Figure 7 The flowchart of a method for determining the in - RRU calibration factors provided by the embodiment of the present application is shown. As Figure 7 shown, the method includes:

[0308] S701: One antenna is determined as a reference antenna among the N antennas of the RRU.

[0309] Exemplarily, if the RRU is provided with 4 antennas, namely antenna 1, antenna 2, antenna 3, and antenna 4, antenna 1 among the 4 antennas can be randomly determined as the reference antenna.

[0310] S702: A first calibration sequence is transmitted through the reference antenna, and the other N - 1 antennas among the N antennas are used for receiving and processing to obtain N - 1 fourth calibration sequences.

[0311] The fourth calibration sequence may be a frequency-domain sequence.

[0312] After receiving the first calibration sequence, the N-1 antennas can process the first calibration sequence to obtain the fourth calibration sequence. For the specific processing operations, please refer to the relevant descriptions in S502 and will not be elaborated here.

[0313] S703: Transmit the first calibration sequence through N-1 antennas, and receive and process it through the reference antenna to obtain N-1 fifth calibration sequences.

[0314] The fifth calibration sequence may be a frequency-domain sequence.

[0315] After receiving the first calibration sequence, the reference antenna can process the first calibration sequence to obtain the fifth calibration sequence. For the specific processing operations, please refer to the relevant descriptions in S502 and will not be elaborated here.

[0316] S704: Determine the in-RRU calibration factor of the RRU according to the N-1 fourth calibration sequences and the N-1 fifth calibration sequences.

[0317] In a possible implementation, the in-RRU calibration factor of the RRU can be determined in the following way:

[0318] Determine N-1 third channel matrices according to the N-1 fourth calibration sequences; determine N-1 fourth channel matrices according to the N-1 fifth calibration sequences; determine N-1 antenna calibration factors according to the N-1 third channel matrices and the N-1 fourth channel matrices; process the calibration factor of the reference antenna and the N-1 antenna calibration factors to obtain the in-RRU calibration factor of the RRU.

[0319] The MMSE criterion can be used for channel estimation to determine the channel matrix, or other methods can also be used to determine the channel matrix.

[0320] In a possible implementation, the N-1 antenna calibration factors can be determined in the following way:

[0321] For any one of the third channel matrices, determine the initial antenna calibration factor according to the third channel matrix and the fourth channel matrix corresponding to the third channel matrix; determine the N-1 antenna calibration factors according to the N-1 initial antenna calibration factors.

[0322] The third channel matrix and the fourth channel matrix corresponding to the third channel matrix may be determined based on the same antenna pair.

[0323] Exemplarily, if the RRU is provided with 4 antennas, namely antenna 1, antenna 2, antenna 3, and antenna 4, the first calibration sequence is sent through antenna 1, and the first calibration sequence is received and processed through antenna 2 to obtain the fourth calibration sequence; if the first calibration sequence is sent through antenna 2, and the first calibration sequence is received and processed through antenna 1 to obtain the fifth calibration sequence; then the third channel matrix is determined based on the initial calibration sequence corresponding to the first calibration sequence and the fourth calibration sequence, and the fourth channel matrix corresponding to the third channel matrix is determined based on the initial calibration sequence corresponding to the first calibration sequence and the fifth calibration sequence.

[0324] In a possible implementation manner, the initial antenna calibration factor can be determined by the following formula:

[0325]

[0326] where, c m2 (k) is the initial antenna calibration factor, is the third channel matrix, is the fourth channel matrix, j2 is the identifier of the reference antenna; m2 is the identifier of any one of the N - 1 antennas, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

[0327] In a possible implementation manner, for any initial antenna calibration factor, the antenna calibration factor is determined by the following formula:

[0328]

[0329] where, is the antenna calibration factor, c m2 (k) is the initial antenna calibration factor.

[0330] In a possible implementation manner, processing the calibration factor of the reference antenna and the N - 1 antenna calibration factors may refer to combining and interpolating the calibration factor of the reference antenna and the N - 1 antenna calibration factors, so as to obtain the in - calibration factor of the RRU at the RE level.

[0331] In Figure 7In the illustrated embodiment, one antenna is determined as a reference antenna among the N antennas of the RRU; a first calibration sequence is transmitted through the reference antenna, and the other N-1 antennas among the N antennas except the reference antenna are used for receiving and processing to obtain N-1 fourth calibration sequences; the first calibration sequence is transmitted through the N-1 antennas, and the reference antenna is used for receiving and processing to obtain N-1 fifth calibration sequences; the in-RRU calibration factor of the RRU is determined according to the N-1 fourth calibration sequences and the N-1 fifth calibration sequences. Taking the reference antenna as a benchmark, the other antennas are aligned with the reference antenna (i.e., the ratio of the uplink channel frequency response to the downlink channel frequency response of the other antennas is adjusted to the ratio of the uplink channel frequency response to the downlink channel frequency response of the reference antenna), that is, the calibration of all antennas in the RRU can be completed through one round of calibration, reducing the overhead of RRU calibration calculation; in addition, the solution provided in the embodiment of the present application supports two-channel RRUs and has good versatility.

[0332] Based on any of the above embodiments, below, a specific example is given to illustrate the calibration process of the present application.

[0333] Taking three RRUs, each RRU is provided with four antennas, namely antenna 1, antenna 2, antenna 3, and antenna 4 as an example. For any one RRU, step 1 is first executed.

[0334] Step 1: In-RRU calibration

[0335] (1.1) Transmission and reception of calibration sequences

[0336] Select antenna 1 as the reference antenna. First, the first calibration sequence is transmitted through antenna 1, and antennas 2, 3, and 4 receive it; then the first calibration sequence is transmitted through antennas 2, 3, and 4, and antenna 1 receives it.

[0337] When transmitting, the initial calibration sequence is processed through frequency-domain mapping, frequency-domain to time-domain transformation, adding CP, etc. to obtain the first calibration sequence, and then the first calibration sequence is transmitted.

[0338] After receiving the first calibration sequence, operations such as removing CP, time-domain to frequency-domain transformation, and frequency-domain demapping are performed to obtain the frequency-domain calibration sequence.

[0339] When antenna 1 transmits and antenna 2 receives, the obtained frequency-domain calibration sequence is When antenna 1 transmits and antenna 3 receives, the obtained frequency-domain calibration sequence is When antenna 1 transmits and antenna 4 receives, the obtained frequency-domain calibration sequence is The three frequency-domain calibration sequences can be called the fourth calibration sequences. When antenna 2 transmits and antenna 1 receives, the obtained frequency-domain calibration sequence is When antenna 3 transmits and antenna 1 receives, the obtained frequency-domain calibration sequence is When antenna 4 transmits and antenna 1 receives, the obtained frequency-domain calibration sequence is The three frequency-domain calibration sequences can be referred to as the fifth calibration sequence.

[0340] Where k = 1 to Q, Q is the length of the frequency-domain calibration sequence and can also be the number of RBs in the system bandwidth; k is the identifier of the unit length of the frequency-domain calibration sequence and can also be the identifier of the RB in the system bandwidth.

[0341] (1.2) Channel estimation

[0342] According to the fourth calibration sequence Determine the third channel matrix

[0343] According to the fifth calibration sequence Determine the fourth channel matrix

[0344] Where the superscripts "DL" and "UL" are directional, "DL" means that other antennas transmit calibration sequences to the reference antenna, and "UL" means that the reference antenna transmits calibration sequences to other antennas.

[0345] (1.3) Calibration factor calculation

[0346] (1.3-1) Calculate the initial antenna calibration factor:

[0347]

[0348] (1.3-2) Normalize c m2 (k), m2 = 2, 3, 4 to obtain the antenna calibration factor:

[0349]

[0350] (1.4) Calibration factor merging and interpolation

[0351] (1.4-1) Calibration factor merging: The calibration factors of 4 antennas (which can be called the in-RRU calibration factors) are:

[0352]

[0353] It should be noted that when there is only one RRU, there is no need to carry the RRU identifier in the in-RRU calibration factor. If there are multiple RRUs, in order to distinguish the in-RRU calibration factors of different RRUs, it is necessary to carry the RRU identifier in the in-RRU calibration factor. The in-RRU calibration factor carrying the RRU identifier can be denoted as

[0354] (1.4-2) Calibration factor interpolation: MMSE filtering, linear interpolation, or even repeated interpolation can be used to interpolate to obtain the calibration factors at the RE level for 4 antennas:

[0355]

[0356] For each antenna, there is a corresponding calibration factor. For any antenna, calibrating the antenna according to the calibration factor corresponding to the antenna may mean compensating the frequency-domain transmission data of the antenna through the calibration factor, and thus completing the calibration of the antenna.

[0357] Exemplarily, if there are 4 antennas, namely antenna 1, antenna 2, antenna 3, and antenna 4, and the calibration factors are compensate the frequency-domain transmission data That is, multiply the calibration factor by the frequency-domain transmission data to obtain the frequency-domain transmission data after calibration compensation:

[0358]

[0359] where, is the frequency-domain transmission data after calibration compensation, n is the identifier of the antenna, and Q is the number of RBs in the system bandwidth.

[0360] If it is necessary to calibrate the frequency-domain reception data then there is:

[0361]

[0362] where, is the frequency-domain reception data after calibration compensation, n is the identifier of the antenna, and Q is the number of RBs in the system bandwidth.

[0363] It should be noted that calibration compensation only needs to be performed in one direction of transmission or reception, and there is no need to perform calibration compensation simultaneously.

[0364] When all 3 RRUs are fully internally calibrated, the in-RRU calibration factors of each RRU can be recorded as:

[0365]

[0366] In the formula, the subscript m represents the identifier of the RRU, and (m,n) represents antenna n of RRU m.

[0367] When the RRU is the second RRU, the in-RRU calibration factor can be recorded as:

[0368]

[0369] In the formula, the subscript r represents the identifier of the second RRU.

[0370] Step 2, Calibration between RRUs

[0371] (2.1) Transmission and Reception of Calibration Sequence

[0372] For the transmission and reception of the calibration sequence, only the reference antennas during the internal calibration of each RRU are required. In this embodiment, they are the antenna 1 of each RRU, that is, the antenna 1 of each RRU is determined as the calibration antenna.

[0373] Taking the antenna 1 of RRU1 as the reference antenna, at this time RRU1 can be called the first RRU. The first calibration sequence is transmitted through the antenna 1 of RRU1 and received by the antenna 1 of RRU2, the antenna 1 of RRU3, and the antenna 1 of RRU4; then the first calibration sequence is transmitted through the antenna 1 of RRU2, the antenna 1 of RRU3, and the antenna 1 of RRU4, and received by the antenna 1 of RRU1.

[0374] During transmission, the initial calibration sequence is processed through frequency-domain mapping, frequency-domain to time-domain transformation, adding CP, etc. to obtain the first calibration sequence, and then the first calibration sequence is transmitted.

[0375] After receiving the first calibration sequence, operations such as removing CP, time-domain to frequency-domain transformation, and frequency-domain demapping are performed to obtain the frequency-domain calibration sequence.

[0376] When the antenna 1 of RRU1 transmits and the antenna 1 of RRUr (i.e., the second RRU) receives and processes, the second calibration sequence obtained is When the antenna 1 of RRUr transmits and the antenna 1 of RRU1 receives and processes, the third calibration sequence obtained is where k = 1 to Q, Q is the length of the frequency-domain calibration sequence, and can also be the number of RBs in the system bandwidth; k is the identifier of the unit length of the frequency-domain calibration sequence, and can also be the identifier of the RB in the system bandwidth.

[0377] (2.2) Channel Estimation

[0378] According to the second calibration sequence Determine the first channel matrix

[0379] According to the third calibration sequence Determine the second channel matrix

[0380] where the superscripts "DL" and "UL" are directional, "DL" indicates that other antennas transmit the calibration sequence to the reference antenna, and "UL" indicates that the reference antenna transmits the calibration sequence to other antennas.

[0381] (2.3) Calculation of Calibration Factor

[0382] (2.3-1) Calculate the initial calibration factor between RRUs:

[0383]

[0384] (1.3-2) Normalize c r→1 (k) for r = 2, 3 to obtain the calibration factor between RRUs:

[0385] (2.4) Calibration factor update

[0386]

[0387] Take the internal calibration factor of RRU1 as the final calibration factor of RRU1. The calibration factor of RRUr can be updated as follows:

[0388]

[0389] Where is the final calibration factor of the RRU, is the calibration factor between RRUs, is the internal calibration factor of the RRU.

[0390] (2.5) Calibration factor merging and interpolation

[0391] (2.5-1) Calibration factor merging: Obtain the calibration factors of all antennas of the 3 RRUs as:

[0392]

[0393] (2.5-2) Calibration factor interpolation: MMSE filtering, linear interpolation, or even repeated interpolation can be used to perform interpolation to obtain the RE-level calibration factor.

[0394] For the calibration between RRUs in step 2, when the calibration antenna of RRUr is not the reference antenna used for internal calibration of RRUr, a correction step can also be added after the calibration factor update to align each antenna in RRUr with antenna 1 of RRU1, that is:

[0395]

[0396] is the corrected final calibration factor of RRUr, is the final calibration factor of the RRU, is the calibration factor of the calibration antenna in RRUr, and m1 is the identifier of the calibration antenna in RRUr.

[0397] Perform calibration factor merging and interpolation after correction.

[0398] The technical solution provided by this application has the following beneficial effects:

[0399] 1. For the single RRU scenario, based on the in-network device near-field air interface radiation solution, antenna calibration can be completed with only one round of calibration factor calculation, significantly reducing the computational complexity.

[0400] 2. For the multi-RRU scenario, only one antenna needs to be selected in each RRU, and by simply repeating the calibration process of the single RRU scenario, calibration between multiple RRUs can be completed.

[0401] 3. Compared with the traditional multi-RRU solution, the solution of this application is applicable to RRU deployment scenarios with any number of RRUs, removing the limitation of mutual transmission among three RRUs and reducing the requirements for deployment conditions.

[0402] 4. For the multi-RRU calibration scenario, this solution proposes an optimal method for calibrating antennas, which has no limitation on the antennas of each RRU participating in the inter-RRU calibration. That is, the inter-RRU calibration is completed through the antenna pair with the best received quality of the calibration sequence, and the calibration of the remaining antennas is completed by the in-RRU calibration with stable air interface channel conditions. The accuracy of RRU calibration is maximally improved.

[0403] Based on any of the above embodiments, when performing in-RRU calibration, the receiving channels can also be pre-calibrated to equalize the frequency responses of the receiving channels.

[0404] Pre-calibration can be performed using methods such as factory calibration or off-line calibration.

[0405] Taking the 5G system as an example, some variables and parameters are described as follows:

[0406] Assume that the number of RBs included in the system bandwidth is Q (the number of REs is Q·12). When performing signal transmission / reception, the channel frequency responses experienced are as follows:

[0407] (1) The transmit-direction channel frequency response of the nth antenna: where N is the number of antennas.

[0408] (2) The receive-direction channel frequency response of the nth antenna: N has the same meaning as above.

[0409] (3) The spatial propagation channel frequency response from the nth antenna to the n'th antenna: and n≠n', and assume That is, the spatial channel propagation characteristics are reciprocal, where represents the spatial propagation channel frequency response from the n'th antenna to the nth antenna.

[0410] Exemplarily, such as Figure 8As shown, if antenna 1 sends a signal to antenna 2, it goes through the transmission channel of antenna 1, the space channel, and the reception channel of antenna 2, and the total frequency response on the subcarrier is If antenna 2 sends a signal to antenna 1, it goes through the transmission channel of antenna 2, the space channel, and the reception channel of antenna 1, and the total frequency response on the subcarrier is

[0411] Taking factory calibration as an example, assume that through factory calibration, the pre-calibration factor of the nth antenna is obtained as:

[0412]

[0413] where A is a constant, and the frequency response of the reception channel of the nth antenna after pre-calibration is:

[0414]

[0415] That is, the frequency response of the reception channel of the nth antenna after pre-calibration is the same as the frequency response of the reception channel of the n'th antenna after pre-calibration That is, the frequency response of the reception channel after pre-calibration satisfies the following formula:

[0416]

[0417] It can be seen from the above formula that after pre-calibration, it is considered that the frequency response characteristics of each reception channel have been equalized.

[0418] If reception channel pre-calibration is performed, in order to avoid pre-calibration failure, it is preferably recommended to perform calibration compensation at the transmitting end during the formal calibration process.

[0419] Figure 9 FIG. shows a schematic structural diagram of a calibration device between RRUs provided by an embodiment of the present application. This device is applied to a network device. There are M RRUs set on the network device, and N antennas are set on each RRU. M is a positive integer greater than 1, and N is a positive integer greater than 1; as Figure 9 shown, this device includes: a memory 910, a transceiver 920, and a processor 930.

[0420] The memory 910 is used to store computer programs;

[0421] The transceiver 920 is used to transmit and receive data under the control of the processor 930;

[0422] The processor 930 is used to read the computer program in the memory 910 and perform the following operations:

[0423] Determine a calibration antenna among the N antennas of each RRU;

[0424] Transmit a first calibration sequence through one of the M calibration antennas, and receive and process through the other M - 1 calibration antennas among the M calibration antennas except one antenna to obtain M - 1 second calibration sequences;

[0425] Transmit a first calibration sequence through M - 1 calibration antennas, and receive and process through one antenna to obtain M - 1 third calibration sequences;

[0426] Calibrate the M RRUs according to the M - 1 second calibration sequences and the M - 1 third calibration sequences.

[0427] In one embodiment, the processor 930 is specifically configured to perform the following operations:

[0428] Determine M - 1 first channel matrices according to the M - 1 second calibration sequences;

[0429] Determine M - 1 second channel matrices according to the M - 1 third calibration sequences;

[0430] Determine M - 1 calibration factors between RRU according to the M - 1 first channel matrices and the M - 1 second channel matrices;

[0431] Calibrate the M RRUs according to the M - 1 calibration factors between RRU.

[0432] In one embodiment, the processor 930 is specifically configured to perform the following operations:

[0433] For any one of the first channel matrices, determine the initial calibration factor between RRU according to the first channel matrix and the second channel matrix corresponding to the first channel matrix;

[0434] Determine M - 1 calibration factors between RRU according to the M - 1 initial calibration factors between RRU.

[0435] In one embodiment, the processor 930 is specifically configured to perform the following operations:

[0436] Determine the initial calibration factor between RRU through the following formula:

[0437]

[0438] where c r→i (k) is the initial calibration factor between RRU; is the first channel matrix;

[0439] is the second channel matrix; i is the identifier of the first RRU, where the first RRU is the RRU where one antenna is located; r is the identifier of the second RRU, where the second RRU is the RRU where any one of the M - 1 calibration antennas is located; j1 is the identifier of one antenna; m1 is the identifier of the calibration antenna in the second RRU; k is the identifier of the resource block in the system bandwidth; Q is the number of resource blocks in the system bandwidth.

[0440] In one implementation, for any initial inter - RRU calibration factor, the processor 930 is specifically configured to perform the following operations:

[0441] Determine the inter - RRU calibration factor through the following formula:

[0442]

[0443] where, is the inter - RRU calibration factor, and c r→i (k) is the initial inter - RRU calibration factor.

[0444] In one implementation, the processor 930 is specifically configured to perform the following operations:

[0445] Obtain the intra - RRU calibration factor of each RRU;

[0446] Determine the final calibration factor of each RRU according to the intra - RRU calibration factor of each RRU and the M - 1 inter - RRU calibration factors;

[0447] For any one RRU, calibrate the RRU according to the final calibration factor of the RRU.

[0448] In one implementation, the processor 930 is specifically configured to perform the following operations:

[0449] Use the intra - RRU calibration factor of the first RRU as the final calibration factor of the first RRU, and use the product of the intra - RRU calibration factor of the second RRU and the corresponding inter - RRU calibration factor of the second RRU as the final calibration factor of the second RRU;

[0450] where, the first RRU is the RRU where one antenna is located, and the second RRU is the RRU where any one of the M - 1 calibration antennas is located.

[0451] In one implementation, if the calibration antenna in the second RRU is not the reference antenna used by the second RRU during internal calibration, the processor 930 is further configured to perform the following operations:

[0452] Correct the final calibration factor of the second RRU through the following formula:

[0453]

[0454] Among them, is the final calibration factor after correction of the second RRU, is the final calibration factor of the second RRU, is the calibration factor of the calibration antenna in the second RRU, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

[0455] In one embodiment, the processor 930 is specifically configured to perform the following operations:

[0456] Among the N antennas of each RRU, the reference antenna used by the RRU during internal calibration is used as the calibration antenna.

[0457] In one embodiment, the processor 930 is specifically configured to perform the following operations:

[0458] For the first RRU, among the N antennas of the first RRU, the reference antenna used by the first RRU during internal calibration is used as the calibration antenna. The first RRU is any one of the M RRUs, and one antenna is the calibration antenna in the first RRU;

[0459] For the second RRU, among the N antennas of the second RRU, the antenna whose received quality of the first calibration sequence is greater than or equal to the preset threshold is used as the calibration antenna. The second RRU is any one of the M RRUs other than the first RRU, and the first calibration sequence is sent by the calibration antenna of the first RRU.

[0460] In one embodiment, for any one RRU, the processor 930 is further configured to perform the following operations:

[0461] Determine one antenna among the N antennas as the reference antenna;

[0462] Send the first calibration sequence through the reference antenna, and receive and process through the other N - 1 antennas among the N antennas except the reference antenna to obtain N - 1 fourth calibration sequences;

[0463] Send the first calibration sequence through the N - 1 antennas, and receive and process through the reference antenna to obtain N - 1 fifth calibration sequences;

[0464] Determine the in - RRU calibration factor of the RRU according to the N - 1 fourth calibration sequences and the N - 1 fifth calibration sequences.

[0465] In one embodiment, the processor 930 is specifically configured to perform the following operations:

[0466] Determine N - 1 third channel matrices according to the N - 1 fourth calibration sequences;

[0467] Determine N - 1 fourth - channel matrices according to N - 1 fifth - calibration sequences;

[0468] Determine N - 1 antenna calibration factors according to N - 1 third - channel matrices and N - 1 fourth - channel matrices;

[0469] Process the calibration factor of the reference antenna and N - 1 antenna calibration factors to obtain the in - RRU calibration factor of the RRU.

[0470] In one implementation, the processor 930 is specifically configured to perform the following operations:

[0471] For any one of the third - channel matrices, determine an initial antenna calibration factor according to the third - channel matrix and the corresponding fourth - channel matrix;

[0472] Determine N - 1 antenna calibration factors according to N - 1 initial antenna calibration factors.

[0473] In one implementation, the processor 930 is specifically configured to perform the following operations:

[0474] Determine the initial antenna calibration factor through the following formula:

[0475]

[0476] where c m2 (k) is the initial antenna calibration factor, is the third - channel matrix, is the fourth - channel matrix, j2 is the identifier of the reference antenna; m2 is the identifier of any one of the N - 1 antennas, k is the identifier of the resource block in the system bandwidth; Q is the number of resource blocks in the system bandwidth.

[0477] In one implementation, for any one of the initial antenna calibration factors, the processor 930 is specifically configured to perform the following operations:

[0478] Determine the antenna calibration factor through the following formula:

[0479]

[0480] where, is the antenna calibration factor, c m2 (k) is the initial antenna calibration factor.

[0481] where, in Figure 9Among them, the bus architecture may include any number of interconnected buses and bridges, specifically, various circuits represented by one or more processors represented by processor 930 and memory represented by memory 910 are linked together. The bus architecture may also link together various other circuits such as peripheral devices, voltage regulators, and power management circuits, etc., which are well known in the art, so they will not be further described herein. The bus interface provides an interface. The transceiver 920 may be multiple components, that is, including a transmitter and a receiver, and provides a unit for communicating with various other devices on a transmission medium, and these transmission media include wireless channels, wired channels, optical fiber cables and other transmission media. The processor 930 is responsible for managing the bus architecture and general processing, and the memory 910 may store data used by the processor 930 when performing operations.

[0482] The processor 930 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.

[0483] It should be noted here that the above device provided in this application can implement all the method steps in the above method embodiments and can achieve the same technical effects. The same parts and beneficial effects as those in the method embodiments in this embodiment will not be specifically described herein.

[0484] Figure 10 It is a schematic structural diagram of another calibration device between RRUs provided in an embodiment of this application. This device is applied to a network device. There are M RRUs set on the network device, and there are N antennas set on each RRU. M is a positive integer greater than 1, and N is a positive integer greater than 1; as Figure 10 shown, this device includes:

[0485] A first determination unit 1010, configured to determine one calibration antenna among the N antennas of each RRU;

[0486] A first transceiver unit 1020, configured to send a first calibration sequence through one of the M calibration antennas, and receive and process through the other M - 1 calibration antennas except one of the M calibration antennas to obtain M - 1 second calibration sequences;

[0487] The second transceiver unit 1030 is configured to send a first calibration sequence through M - 1 calibration antennas, and receive and process through one antenna to obtain M - 1 third calibration sequences;

[0488] The first calibration processing unit 1040 is configured to perform calibration processing on M RRUs according to M - 1 second calibration sequences and M - 1 third calibration sequences.

[0489] In an implementation, the first calibration processing unit 1040 is specifically configured to:

[0490] Determine M - 1 first channel matrices according to M - 1 second calibration sequences;

[0491] Determine M - 1 second channel matrices according to M - 1 third calibration sequences;

[0492] Determine M - 1 inter - RRU calibration factors according to M - 1 first channel matrices and M - 1 second channel matrices;

[0493] Perform calibration processing on M RRUs according to M - 1 inter - RRU calibration factors.

[0494] In an implementation, the first calibration processing unit 1040 is specifically configured to:

[0495] For any one of the first channel matrices, determine an initial inter - RRU calibration factor according to the first channel matrix and the second channel matrix corresponding to the first channel matrix;

[0496] Determine M - 1 inter - RRU calibration factors according to M - 1 initial inter - RRU calibration factors.

[0497] In an implementation, the first calibration processing unit 1040 is specifically configured to:

[0498] Determine the initial inter - RRU calibration factor through the following formula:

[0499]

[0500] where, c r→i (k) is the initial inter - RRU calibration factor; is the first channel matrix;

[0501] is the second channel matrix; i is the identifier of the first RRU, and the first RRU is the RRU where one antenna is located; r is the identifier of the second RRU, and the second RRU is the RRU where any one of the M - 1 calibration antennas is located; j1 is the identifier of one antenna; m1 is the identifier of the calibration antenna in the second RRU; k is the identifier of the resource block in the system bandwidth; Q is the number of resource blocks in the system bandwidth.

[0502] In one embodiment, for any initial inter-RRU calibration factor, the first calibration processing unit 1040 is specifically configured to:

[0503] Determine the inter-RRU calibration factor through the following formula:

[0504]

[0505] Wherein, is the inter-RRU calibration factor; c r→i (k) is the initial inter-RRU calibration factor.

[0506] In one embodiment, the first calibration processing unit 1040 is specifically configured to:

[0507] Obtain the intra-RRU calibration factor of each RRU;

[0508] Determine the final calibration factor of each RRU according to the intra-RRU calibration factor of each RRU and M-1 inter-RRU calibration factors;

[0509] For any one RRU, perform calibration processing on the RRU according to the final calibration factor of the RRU.

[0510] In one embodiment, the first calibration processing unit 1040 is specifically configured to:

[0511] Use the intra-RRU calibration factor of the first RRU as the final calibration factor of the first RRU, and use the product of the intra-RRU calibration factor of the second RRU and the inter-RRU calibration factor corresponding to the second RRU as the final calibration factor of the second RRU;

[0512] Wherein, the first RRU is the RRU where one antenna is located, and the second RRU is the RRU where any one of the M-1 calibration antennas is located.

[0513] In one embodiment, if the calibration antenna in the second RRU is not the reference antenna used by the second RRU during internal calibration, the device further includes:

[0514] A correction unit for correcting the final calibration factor of the second RRU through the following formula:

[0515]

[0516] Wherein, is the corrected final calibration factor of the second RRU, is the final calibration factor of the second RRU, is the calibration factor of the calibration antenna in the second RRU, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

[0517] In one embodiment, the first determination unit 1010 is specifically configured to:

[0518] Among the N antennas of each RRU, use the reference antenna used by the RRU during internal calibration as the calibration antenna.

[0519] In one embodiment, the first determination unit 1010 is specifically configured to:

[0520] For the first RRU, among the N antennas of the first RRU, use the reference antenna used by the first RRU during internal calibration as the calibration antenna. The first RRU is any one of the M RRUs, and one antenna is the calibration antenna in the first RRU;

[0521] For the second RRU, among the N antennas of the second RRU, use the antenna whose received quality of the first calibration sequence is greater than or equal to a preset threshold as the calibration antenna. The second RRU is any one of the M RRUs other than the first RRU, and the first calibration sequence is sent by the calibration antenna of the first RRU.

[0522] Figure 11 This is a schematic structural diagram of another calibration device between RRUs provided by an embodiment of the present application. In Figure 10 Based on the shown device structure, the device further includes:

[0523] A second determination unit 1050, configured to determine one antenna as a reference antenna among the N antennas;

[0524] A third transceiver unit 1060, configured to send a first calibration sequence through the reference antenna, and receive and process through the other N - 1 antennas among the N antennas except the reference antenna to obtain N - 1 fourth calibration sequences;

[0525] A fourth transceiver unit 1070, configured to send the first calibration sequence through the N - 1 antennas, and receive and process through the reference antenna to obtain N - 1 fifth calibration sequences;

[0526] A second calibration processing unit 1080, configured to determine the in - RRU calibration factor of the RRU according to the N - 1 fourth calibration sequences and the N - 1 fifth calibration sequences.

[0527] In one embodiment, the second calibration processing unit 1080 is specifically configured to:

[0528] Determine N - 1 third channel matrices according to the N - 1 fourth calibration sequences;

[0529] Determine N - 1 fourth channel matrices according to the N - 1 fifth calibration sequences;

[0530] Determine N - 1 antenna calibration factors according to N - 1 third channel matrices and N - 1 fourth channel matrices;

[0531] Process the calibration factor of the reference antenna and the N - 1 antenna calibration factors to obtain the in - RRU calibration factor of the RRU.

[0532] In one implementation manner, the second calibration processing unit 1080 is specifically configured to:

[0533] For any one of the third channel matrices, determine an initial antenna calibration factor according to the third channel matrix and the corresponding fourth channel matrix;

[0534] Determine N - 1 antenna calibration factors according to the N - 1 initial antenna calibration factors.

[0535] In one implementation manner, the second calibration processing unit 1080 is specifically configured to:

[0536] Determine the initial antenna calibration factor through the following formula:

[0537]

[0538] where, c m2 (k) is the initial antenna calibration factor, is the third channel matrix, is the fourth channel matrix, j2 is the identifier of the reference antenna; m2 is the identifier of any one of the N - 1 antennas, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

[0539] In one implementation manner, for any one of the initial antenna calibration factors, the second calibration processing unit 1080 is specifically configured to:

[0540] Determine the antenna calibration factor through the following formula:

[0541]

[0542] where, is the antenna calibration factor, c m2 (k) is the initial antenna calibration factor.

[0543] It should be noted that the division of units in the embodiments of the present application is illustrative, only a logical function division, and there may be other division methods in actual implementation. In addition, in each embodiment of the present application, each functional unit may be integrated in a processing unit, or each unit may exist physically alone, or two or more units may be integrated in one unit. The above - integrated unit may be implemented in the form of hardware or in the form of a software functional unit.

[0544] If the above 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 this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the methods of the various embodiments of this application. The foregoing storage medium includes: USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs, etc., which can store program codes of various types.

[0545] It should be noted here that the above device provided by this application can implement all the method steps of the above method embodiments and can achieve the same technical effects. Therefore, the same parts and beneficial effects as those in the method embodiments will not be specifically described in this embodiment.

[0546] This application embodiment also provides a processor-readable storage medium, which stores a computer program for causing the processor to execute all the method steps of the above method embodiments.

[0547] The processor-readable storage medium can be any available medium or data storage device accessible by a computer, including but not limited to magnetic memories (such as floppy disks, hard disks, magnetic tapes, magneto-optical discs (MOs), etc.), optical memories (such as CDs, DVDs, BDs, HVDs, etc.), and semiconductor memories (such as ROMs, EPROMs, EEPROMs, non-volatile memories (NAND FLASH), solid-state drives (SSDs)), etc.

[0548] This application embodiment also provides a computer program product, including a computer program that, when executed by a processor, implements all the method steps of the above method embodiments.

[0549] Those skilled in the art should understand that the embodiments of this application can be provided as a method, a system, or a computer program product. Therefore, this application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, this application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories and optical memories, etc.) that contain computer-usable program codes.

[0550] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer-executable instructions. These computer-executable instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing device produce means for implementing the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or means for implementing the functions specified in one or more of the blocks.

[0551] These processor-executable instructions can also be stored in a processor-readable memory that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the processor-readable memory produce a manufacture including instruction means that implement the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or means for implementing the functions specified in one or more of the blocks.

[0552] These processor-executable instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operational steps are performed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more of the flows Figure 1 one or more of the flows and / or blocks Figure 1 or means for implementing the functions specified in one or more of the blocks.

[0553] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalent technologies, this application is also intended to include these modifications and variations.

Claims

1. A calibration method between remote radio units (RRUs), characterized in that Applied to a network device, where M RRU are provided on the network device, and N antennas are provided on each RRU, M is a positive integer greater than 1, N is a positive integer greater than 1, and the method includes: Determine one calibration antenna among the N antennas of each RRU; Send a first calibration sequence through one of the M calibration antennas, and receive and process through the other M - 1 calibration antennas among the M calibration antennas except the one antenna, to obtain M - 1 second calibration sequences; Send the first calibration sequence through the M - 1 calibration antennas, and receive and process through the one antenna, to obtain M - 1 third calibration sequences; Perform calibration processing on the M RRU according to the M - 1 second calibration sequences and the M - 1 third calibration sequences.

2. The method according to claim 1, wherein The performing calibration processing on the M RRU according to the M - 1 second calibration sequences and the M - 1 third calibration sequences includes: Determine M - 1 first channel matrices according to the M - 1 second calibration sequences; Determine M - 1 second channel matrices according to the M - 1 third calibration sequences; Determine M - 1 calibration factors between RRU according to the M - 1 first channel matrices and the M - 1 second channel matrices; Perform calibration processing on the M RRU according to the M - 1 calibration factors between RRU.

3. The method according to claim 2, wherein Determining M - 1 calibration factors between RRU according to the M - 1 first channel matrices and the M - 1 second channel matrices includes: For any one of the first channel matrices, determine an initial calibration factor between RRU according to the first channel matrix and the second channel matrix corresponding to the first channel matrix; Determine the M - 1 calibration factors between RRU according to the M - 1 initial calibration factors between RRU.

4. The method according to claim 3, characterized in that, The determining an initial calibration factor between RRU according to the first channel matrix and the second channel matrix corresponding to the first channel matrix includes: Determine the initial calibration factor between RRU through the following formula: Among them, c r→i (k) is the calibration factor between the initial RRUs; is the first channel matrix; is the second channel matrix; i is the identifier of the first RRU, and the first RRU is the RRU where the one antenna is located; r is the identifier of the second RRU, and the second RRU is the RRU where any one of the M-1 calibration antennas is located; j1 is the identifier of the one antenna; m1 is the identifier of the calibration antenna in the second RRU; k is the identifier of the resource block in the system bandwidth; Q is the number of resource blocks in the system bandwidth.

5. The method according to claim 4, wherein For any one of the initial calibration factors between RRU, determining a calibration factor between RRU according to the initial calibration factor between RRU includes: Determine the calibration factor between RRU through the following formula: Among them, is the calibration factor between the RRU; c r→i (k) is the initial calibration factor between the RRU.

6. The method according to any one of claims 2-5, characterized in that The performing calibration processing on the M RRU according to the M - 1 calibration factors between RRU includes: Obtain the calibration factor within each RRU; Determine the final calibration factor of each RRU according to the calibration factor within each RRU and the M - 1 calibration factors between RRU; For any one of the RRU, perform calibration processing on the RRU according to the final calibration factor of the RRU.

7. The method according to claim 6, wherein The determining the final calibration factor of each RRU according to the calibration factor within each RRU and the M - 1 calibration factors between RRU includes: Take the calibration factor within the first RRU as the final calibration factor of the first RRU, and take the product of the calibration factor within the second RRU and the calibration factor between RRU corresponding to the second RRU as the final calibration factor of the second RRU; Wherein, the first RRU is the RRU where the one antenna is located, and the second RRU is the RRU where any one of the M-1 calibration antennas is located.

8. The method according to claim 7, characterized in that, If the calibration antenna in the second RRU is not the reference antenna used by the second RRU during internal calibration, the method further includes: Correcting the final calibration factor of the second RRU through the following formula: Among them, is the final calibration factor after correction for the second RRU, is the final calibration factor of the second RRU, is the calibration factor of the calibration antenna in the second RRU, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

9. The method according to claim 1, wherein Determining one calibration antenna among the N antennas of each RRU includes: Among the N antennas of each RRU, using the reference antenna used by the RRU during internal calibration as the calibration antenna.

10. The method according to claim 1, characterized in that, Determining one calibration antenna among the N antennas of each RRU includes: For the first RRU, among the N antennas of the first RRU, using the reference antenna used by the first RRU during internal calibration as the calibration antenna, where the first RRU is any one of the M RRUs, and the one antenna is the calibration antenna in the first RRU; For the second RRU, among the N antennas of the second RRU, using the antenna with the reception quality of the first calibration sequence being greater than or equal to the preset threshold as the calibration antenna, where the second RRU is any one of the M RRUs other than the first RRU, and the first calibration sequence is sent by the calibration antenna of the first RRU.

11. The method according to claim 6, characterized in that For any one RRU, the method further includes: Determining one antenna among the N antennas as the reference antenna; Sending the first calibration sequence through the reference antenna, and receiving and processing through the other N-1 antennas among the N antennas except the reference antenna to obtain N-1 fourth calibration sequences; Sending the first calibration sequence through the N-1 antennas, and receiving and processing through the reference antenna to obtain N-1 fifth calibration sequences; Determining the in-RRU calibration factor of the RRU according to the N-1 fourth calibration sequences and the N-1 fifth calibration sequences.

12. The method according to claim 11, characterized in that The determining the in-RRU calibration factor of the RRU according to the N-1 fourth calibration sequences and the N-1 fifth calibration sequences includes: Determining N-1 third channel matrices according to the N-1 fourth calibration sequences; Determining N-1 fourth channel matrices according to the N-1 fifth calibration sequences; Determining N-1 antenna calibration factors according to the N-1 third channel matrices and the N-1 fourth channel matrices; Processing the calibration factor of the reference antenna and the N-1 antenna calibration factors to obtain the in-RRU calibration factor of the RRU.

13. The method according to claim 12, characterized in that, The determining N-1 antenna calibration factors according to the N-1 third channel matrices and the N-1 fourth channel matrices includes: For any one third channel matrix, determining an initial antenna calibration factor according to the third channel matrix and the fourth channel matrix corresponding to the third channel matrix; Determining the N-1 antenna calibration factors according to the N-1 initial antenna calibration factors.

14. The method according to claim 13, wherein Determining an initial antenna calibration factor according to the third channel matrix and a fourth channel matrix corresponding to the third channel matrix includes: Determining the initial antenna calibration factor through the following formula: where c m2 (k) is the initial antenna calibration factor, is the third channel matrix, is the fourth channel matrix, j2 is the identifier of the reference antenna; m2 is the identifier of any one of the N-1 antennas, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

15. The method according to claim 14, wherein For any one of the initial antenna calibration factors, determining an antenna calibration factor according to the initial antenna calibration factor includes: Determining the antenna calibration factor through the following formula: Among them, is the antenna calibration factor, c m2 (k) is the initial antenna calibration factor.

16. A calibration device between remote radio units (RRUs), characterized in that, Applied to a network device, where M RRU are provided on the network device, and N antennas are provided on each RRU, M is a positive integer greater than 1, N is a positive integer greater than 1, and the device includes a memory, a transceiver, and a processor: The memory is used to store a computer program; the transceiver is used to transmit and receive data under the control of the processor; the processor is used to read the computer program in the memory and perform the following operations: Determine one calibration antenna among the N antennas of each RRU; Send a first calibration sequence through one of the M calibration antennas, and receive and process through the other M-1 calibration antennas among the M calibration antennas to obtain M-1 second calibration sequences; Send the first calibration sequence through the M-1 calibration antennas, and receive and process through the one antenna to obtain M-1 third calibration sequences; Perform calibration processing on the M RRU according to the M-1 second calibration sequences and the M-1 third calibration sequences.

17. The device according to claim 16, characterized in that, The processor is specifically used to perform the following operations: Determine M-1 first channel matrices according to the M-1 second calibration sequences; Determine M-1 second channel matrices according to the M-1 third calibration sequences; Determine calibration factors between M-1 RRU according to the M-1 first channel matrices and the M-1 second channel matrices; Perform calibration processing on the M RRU according to the calibration factors between the M-1 RRU.

18. The device according to claim 17, characterized in that The processor is specifically used to perform the following operations: For any one of the first channel matrices, determine an initial calibration factor between RRU according to the first channel matrix and a second channel matrix corresponding to the first channel matrix; Determine the calibration factors between the M-1 RRU according to the M-1 initial calibration factors between RRU.

19. The device according to claim 18, wherein The processor is specifically used to perform the following operations: Determine the initial calibration factor between RRU through the following formula: where c r→i (k) is the calibration factor between the initial RRUs; is the first channel matrix; is the second channel matrix; i is the identifier of the first RRU, and the first RRU is the RRU where the one antenna is located; r is the identifier of the second RRU, and the second RRU is the RRU where any one of the M-1 calibration antennas is located; j1 is the identifier of the one antenna; m1 is the identifier of the calibration antenna in the second RRU; k is the identifier of the resource block in the system bandwidth; Q is the number of resource blocks in the system bandwidth.

20. The device according to claim 19, characterized in that For any one of the initial calibration factors between RRU, the processor is specifically used to perform the following operations: Determine the calibration factor between RRU through the following formula: Among them, is the calibration factor between the RRU, c r→i (k) is the initial calibration factor between the RRU.

21. The device according to any one of claims 17-20, characterized in that, The processor is specifically used to perform the following operations: Obtain the calibration factor within each RRU; Determine the final calibration factor of each RRU according to the calibration factor within each RRU and the calibration factors between the M-1 RRU; For any one of the RRU, perform calibration processing on the RRU according to the final calibration factor of the RRU.

22. The device according to claim 21, characterized in that, The processor is specifically used to perform the following operations: Take the in-RRU calibration factor of the first RRU as the final calibration factor of the first RRU, and take the product of the in-RRU calibration factor of the second RRU and the between-RRU calibration factor corresponding to the second RRU as the final calibration factor of the second RRU; Wherein, the first RRU is the RRU where the one antenna is located, and the second RRU is the RRU where any one of the M-1 calibration antennas is located.

23. The device according to claim 22, characterized in that, If the calibration antenna in the second RRU is not the reference antenna used by the second RRU during internal calibration, the processor is further configured to perform the following operations: Correct the final calibration factor of the second RRU through the following formula: Wherein, is the final calibration factor after correction for the second RRU, is the final calibration factor of the second RRU, is the calibration factor of the calibration antenna in the second RRU, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

24. The device according to claim 16, characterized in that, Specifically, the processor is configured to perform the following operations: Among the N antennas of each RRU, take the reference antenna used by the RRU during internal calibration as the calibration antenna.

25. The device according to claim 16, characterized in that, Specifically, the processor is configured to perform the following operations: For the first RRU, among the N antennas of the first RRU, take the reference antenna used by the first RRU during internal calibration as the calibration antenna, where the first RRU is any one of the M RRUs, and the one antenna is the calibration antenna in the first RRU; For the second RRU, among the N antennas of the second RRU, take the antenna whose received quality of the first calibration sequence is greater than or equal to a preset threshold as the calibration antenna, where the second RRU is any one of the M RRUs other than the first RRU, and the first calibration sequence is sent by the calibration antenna of the first RRU.

26. The device according to claim 21, characterized in that, For any one RRU, the processor is further configured to perform the following operations: Determine one antenna among the N antennas as the reference antenna; Send the first calibration sequence through the reference antenna, and receive and process through the other N-1 antennas among the N antennas except the reference antenna to obtain N-1 fourth calibration sequences; Send the first calibration sequence through the N-1 antennas, and receive and process through the reference antenna to obtain N-1 fifth calibration sequences; Determine the in-RRU calibration factor of the RRU according to the N-1 fourth calibration sequences and the N-1 fifth calibration sequences.

27. The device according to claim 26, characterized in that, Specifically, the processor is configured to perform the following operations: Determine N-1 third channel matrices according to the N-1 fourth calibration sequences; Determine N-1 fourth channel matrices according to the N-1 fifth calibration sequences; Determine N-1 antenna calibration factors according to the N-1 third channel matrices and the N-1 fourth channel matrices; Process the calibration factor of the reference antenna and the N-1 antenna calibration factors to obtain the in-RRU calibration factor of the RRU.

28. The device according to claim 27, wherein Specifically, the processor is configured to perform the following operations: For any one third channel matrix, determine the initial antenna calibration factor according to the third channel matrix and the fourth channel matrix corresponding to the third channel matrix; Determine the N-1 antenna calibration factors according to the N-1 initial antenna calibration factors.

29. The device according to claim 28, characterized in that, The processor is specifically configured to perform the following operations: Determine the initial antenna calibration factor through the following formula: Among them, c m2 (k) is the initial antenna calibration factor, is the third channel matrix, is the fourth channel matrix, j2 is the identifier of the reference antenna; m2 is the identifier of any one of the N - 1 antennas, k is the identifier of the resource block in the system bandwidth, and Q is the number of resource blocks in the system bandwidth.

30. The device according to claim 29, wherein For any one of the initial antenna calibration factors, the processor is specifically configured to perform the following operations: Determine the antenna calibration factor through the following formula: Among them, is the antenna calibration factor, c m2 (k) is the initial antenna calibration factor.

31. A calibration device between remote radio units (RRUs), characterized in that, Applied to a network device, where M RRU are provided on the network device, and N antennas are provided on each RRU, M is a positive integer greater than 1, N is a positive integer greater than 1, and the device includes: A first determination unit, configured to determine one calibration antenna among the N antennas of each RRU; A first transceiver unit, configured to send a first calibration sequence through one of the M calibration antennas, and receive and process through the other M - 1 calibration antennas among the M calibration antennas, to obtain M - 1 second calibration sequences; A second transceiver unit, configured to send the first calibration sequence through the M - 1 calibration antennas, and receive and process through the one antenna, to obtain M - 1 third calibration sequences; A first calibration processing unit, configured to perform calibration processing on the M RRU according to the M - 1 second calibration sequences and the M - 1 third calibration sequences.

32. A processor-readable storage medium, characterized in that, The processor-readable storage medium stores a computer program, and the computer program is used to cause the processor to execute the method according to any one of claims 1 to 15.

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