Frequency and time resource scheduling method and device for antenna calibration in distributed multiple-input multiple-output

Abstract

The present invention discloses a time-frequency resource scheduling method and system for antenna calibration under distributed multiple-input multiple-output, including: classifying several radio frequency units within the cooperation range according to a predetermined rule, and clustering the radio frequency units at the same level with the radio frequency unit at the previous level as the central node; according to their classification, the radio frequency units within the cooperation range send and receive calibration sequences in an inter-level and inter-cluster time-frequency domain scheduling manner; determining the range of radio frequency units that re-send and receive calibration sequences according to the interference degree of sending and receiving calibration sequences between levels, dividing the calibration of radio frequency units within the cooperation range into time domain stages, and sending and receiving calibration sequences in the above-mentioned inter-level and inter-cluster time-frequency domain scheduling manner within the set time domain stages; calculating the final calibration factor according to the radio frequency unit level. By adopting the present invention, it is possible to reuse as much time domain resources as possible on the basis of reducing calibration errors, and achieve efficient scheduling of antenna calibration in the scenario of multi-node cooperation.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and particularly to a time-frequency resource scheduling method and device for antenna calibration in distributed multiple-input multiple-output (DMIMO). Background Art

[0002] To cope with the rapid growth of wireless data service demands and the challenges brought by new service requirements, future next-generation wireless networks need to support scenarios such as high quality, high transmission rate, high user density, high mobility, and low latency. The multiple-input multiple-output (MIMO) technology equipped with a large-scale antenna array can greatly improve the system capacity and is one of the key technologies for future next-generation wireless networks. Deploying so many antennas at a single base station is a great challenge, and a more practical solution is to distribute and jointly serve users with a large-scale array. The distributed MIMO (DMIMO) networking technology in which multiple distributed radio frequency units jointly transmit to form a large-scale MIMO downlink is a new structure for future wireless access networks.

[0003] The disadvantage of the prior art is that there are calibration errors in existing DMIMO. Summary of the Invention

[0004] The present invention provides a time-frequency resource scheduling method and system for antenna calibration in distributed multiple-input multiple-output, a calibration sequence sending method, a device, a radio frequency unit, and a medium, so as to solve the problem of calibration errors existing in existing DMIMO.

[0005] The present invention provides the following technical solutions:

[0006] A time-frequency resource scheduling method for antenna calibration in DMIMO, comprising:

[0007] Classifying several radio frequency units within the cooperation range according to a predetermined rule, and clustering the radio frequency units at the same level with the radio frequency unit at the previous level as the central node;

[0008] The radio frequency units within the cooperation range send and receive calibration sequences in a time-frequency domain scheduling manner between levels and between clusters according to their classification;

[0009] Determining the range of radio frequency units that re-send and receive calibration sequences according to the interference degree of sending and receiving calibration sequences between levels, dividing the calibration of the radio frequency units within the cooperation range into time domain stages, and sending and receiving calibration sequences in the above-mentioned time-frequency domain scheduling manner between levels and between clusters within the set time domain stages;

[0010] Calculating the final calibration factor according to the radio frequency unit level.

[0011] In implementation, grading a number of radio frequency units within the collaboration range according to a predetermined rule includes:

[0012] Determine the central node within the collaboration range, take this central node as the first-level node, make a cluster with the first-level node as the center, and obtain the first-level cluster;

[0013] Take the nodes within the cluster except the central node as the second-level nodes, make a cluster with the second-level nodes as the center and outside the first-level cluster, and obtain the second-level cluster;

[0014] Take the nodes within the cluster except the central node as the third-level nodes, and so on. A cluster with the nth-level node as the center and outside the (n - 1)th-level cluster is called the nth-level cluster, and take the nodes within the cluster except the central node as the (n + 1)th-level nodes.

[0015] In implementation, determine the first-level node in the following way:

[0016] Take the center of the radio frequency unit distribution area as the center of a circle, make a cluster with a preset threshold as the radius, make a cluster with the radio frequency units within the cluster as the center, and take the one with a higher number of radio frequency units included in each cluster as the first-level node within the collaboration range.

[0017] In implementation, determine the final calibration factor in the following way:

[0018] Within the cluster, perform antenna calibration with the central node of this cluster as the reference radio frequency unit. The calibration factor of this cluster is the product of the calibration factor within the cluster and the factor obtained by calibrating the central node of this cluster in the upper-level cluster.

[0019] In implementation, the time-domain scheduling method between levels and between clusters includes:

[0020] Transmit and receive calibration sequences in the same time slot at every other level.

[0021] In implementation, the frequency-domain scheduling method between levels and between clusters includes:

[0022] When odd-level nodes send calibration sequences to even-level nodes, send them at different frequency points, and determine the number of frequency points used according to the degree of even nodes. Conversely, send calibration sequences according to the same rule.

[0023] In implementation, perform time-domain stage division on the radio frequency units within the system according to the interference degree of transmitting and receiving calibration sequences between levels, including:

[0024] In a network divided into n-level clusters, start comparing from the second level and perform time-domain stage division: The kth-level node receives a calibration sequence and is interfered by signals from nodes such as the (k - 3)th level or the (k + 3)th level. If the signal-to-interference-plus-noise ratio of the received useful signal is lower than the preset threshold, make the cluster where the useful signal is located re-perform antenna calibration in the next time domain stage. Otherwise, take the calibration result of this time as the final calibration result of the cluster where the useful signal is located.

[0025] A time-frequency resource scheduling system for antenna calibration under DMIMO, comprising:

[0026] A hierarchical clustering module, configured to classify a plurality of radio frequency units within the cooperation range according to a predetermined rule, and cluster the radio frequency units of the same level with the radio frequency unit of the previous level as the central node;

[0027] A scheduling module, configured to enable the radio frequency units within the cooperation range to send and receive calibration sequences in an inter-level and inter-cluster time-frequency domain scheduling manner according to their division;

[0028] A re-partitioning module, configured to determine the range of radio frequency units for re-sending and receiving calibration sequences according to the interference degree of sending and receiving calibration sequences between levels, divide the calibration of the radio frequency units within the cooperation range in the time domain stage, and send and receive calibration sequences in the above-mentioned inter-level and inter-cluster time-frequency domain scheduling manner within the set time domain stage;

[0029] A calibration factor calculation module, configured to calculate the final calibration factor according to the radio frequency unit level.

[0030] In implementation, the hierarchical clustering module is further configured to classify a plurality of radio frequency units within the cooperation range according to a predetermined rule in the following manner:

[0031] Determine the central node within the cooperation range, use this central node as the first-level node, make a cluster with the first-level node as the center, and obtain the first-level cluster;

[0032] Use the intra-cluster nodes except the central node as the second-level nodes, make a cluster with the second-level nodes as the center and outside the first-level cluster, and obtain the second-level cluster;

[0033] Use the intra-cluster nodes except the central node as the third-level nodes, and so on. The cluster with the nth-level node as the center and outside the (n - 1)th-level cluster is called the nth-level cluster, and the intra-cluster nodes except the central node are used as the (n + 1)th-level nodes.

[0034] In implementation, the hierarchical clustering module is further configured to determine the first-level node in the following manner:

[0035] Use the center of the radio frequency unit distribution area as the center of the circle, make a cluster with a preset threshold as the radius, make a cluster with the radio frequency units within the cluster as the center, and select the one with a higher number of radio frequency units in each cluster as the first-level node within the cooperation range.

[0036] In implementation, the calibration factor calculation module is further configured to determine the final calibration factor in the following manner:

[0037] Within the cluster, use the central node of this cluster as the reference radio frequency unit for antenna calibration. The calibration factor of this cluster is the product of the intra-cluster calibration factor and the factor obtained by calibrating the central node of this cluster in the previous-level cluster.

[0038] During implementation, the scheduling module is further configured to perform inter-level and inter-cluster time-domain scheduling in the following manner:

[0039] Transmit and receive calibration sequences at the same time slot for every other level.

[0040] During implementation, the scheduling module is further configured to perform inter-level and inter-cluster frequency-domain scheduling in the following manner:

[0041] When odd-level nodes send calibration sequences to even-level nodes, they send at different frequency points, and the number of frequency points utilized is determined according to the degree of the even nodes. Conversely, calibration sequences are sent according to the same rule.

[0042] During implementation, the re-partitioning module is further configured to perform time-domain stage partitioning on the RF units in the system according to the interference degree of inter-level transmission and reception of calibration sequences in the following manner:

[0043] In a network divided into n-level clusters, starting from the second level for comparison, perform time-domain stage partitioning: The k-level nodes receive calibration sequences and are interfered by signals from nodes such as the k - 3 level or the k + 3 level. If the signal-to-interference-plus-noise ratio of the received useful signal is lower than the preset threshold, the cluster where the useful signal is located will re-perform antenna calibration in the next time domain stage. Otherwise, the current calibration result will be used as the final calibration result of the cluster where the useful signal is located.

[0044] A calibration sequence transmission method, comprising:

[0045] The RF unit determines the calibration sequence to be transmitted and the RF unit that receives the calibration sequence. Among them, each RF unit is composed according to the DMIMO networking technology, and each RF unit is divided into at least two levels. The same-level RF units are clustered with the upper-level RF unit as the central reference node. The RF unit that receives the calibration sequence is the central reference node, and several RF units that send calibration sequences and one RF unit that receives the calibration sequence form a cluster;

[0046] The RF unit sends the calibration sequence to the RF unit that receives the calibration sequence.

[0047] During implementation, when each RF unit is graded, it is graded according to the geographical location.

[0048] During implementation, when the RF units in the same cluster send calibration sequences to the RF unit that receives the calibration sequence, the frequency-domain resources and / or time resources used are the same, and are different from those of other clusters and / or other levels of RF units.

[0049] During implementation, the preset value of the cluster radius of the cluster is adjusted according to the number of frequency-domain resources.

[0050] During implementation, it further includes:

[0051] Determine the cluster radius of the cluster according to the interference degree of inter-level transmission and reception of calibration sequences.

[0052] In implementation, the highest-level radio frequency unit is the radio frequency unit in the cluster with the highest number of radio frequency units in each sub-cluster.

[0053] A radio frequency unit includes:

[0054] A processor for reading a program in a memory and performing the following processes:

[0055] Determine the calibration sequence to be sent and the radio frequency unit that receives the calibration sequence, where each radio frequency unit is composed according to the DMIMO networking technology, each radio frequency unit is divided into at least two levels, the radio frequency units at the same level are clustered with the upper-level radio frequency unit as the central reference node, the radio frequency unit that receives the calibration sequence is the central reference node, and several radio frequency units that send the calibration sequence and one radio frequency unit that receives the calibration sequence form a cluster;

[0056] Send the calibration sequence to the radio frequency unit that receives the calibration sequence;

[0057] A transceiver for receiving and sending data under the control of the processor.

[0058] In implementation, when each radio frequency unit is graded, it is graded according to the geographical location.

[0059] In implementation, when the radio frequency units in the same sub-cluster send the calibration sequence to the radio frequency unit that receives the calibration sequence, the frequency domain resources and / or time resources used are the same, and are different from those of other sub-clusters and / or radio frequency units at other levels.

[0060] In implementation, the preset value of the cluster radius of the clustering is adjusted according to the number of frequency domain resources.

[0061] In implementation, it further includes:

[0062] Determine the cluster radius of the clustering according to the interference degree of sending and receiving the calibration sequence between levels.

[0063] In implementation, the highest-level radio frequency unit is the radio frequency unit in the cluster with the highest number of radio frequency units in each sub-cluster.

[0064] A calibration sequence sending device includes:

[0065] A determination module for determining the calibration sequence to be sent and the radio frequency unit that receives the calibration sequence, where each radio frequency unit is composed according to the DMIMO networking technology, each radio frequency unit is divided into at least two levels, the radio frequency units at the same level are clustered with the upper-level radio frequency unit as the central reference node, the radio frequency unit that receives the calibration sequence is the central reference node, and several radio frequency units that send the calibration sequence and one radio frequency unit that receives the calibration sequence form a cluster;

[0066] A sending module, configured to send a calibration sequence to a radio frequency unit that receives the calibration sequence.

[0067] In implementation, when the radio frequency units are classified, they are classified according to geographical location.

[0068] In implementation, the sending module is further configured such that when radio frequency units in the same cluster send a calibration sequence to a radio frequency unit that receives the calibration sequence, the frequency domain resources and / or time resources used are the same, and are different from those of radio frequency units in other clusters and / or other classifications.

[0069] In implementation, the preset value of the cluster radius of clustering is adjusted according to the number of frequency domain resources.

[0070] In implementation, it further includes:

[0071] Determine the cluster radius of clustering according to the interference degree of sending and receiving calibration sequences between levels.

[0072] In implementation, the radio frequency units at the highest level are the radio frequency units in the cluster with the highest number of radio frequency units included in each cluster.

[0073] A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program for executing the above calibration sequence sending method.

[0074] The beneficial effects of the present invention are as follows:

[0075] In the technical solution provided by the present invention, due to the time-frequency resource scheduling for antenna calibration considering calibration errors, the scheme of clustering radio frequency units and performing global calibration level by level can avoid excessive calibration errors caused by the position dispersion of the radio frequency unit array with calibration relationships. The calibration period can be shortened as much as possible by having radio frequency units at alternate levels send calibration sequences simultaneously in the time domain, and frequency domain division is performed on the radio frequency units that send calibration sequences simultaneously to avoid interference. Therefore, it is possible to reuse time domain resources as much as possible on the basis of reducing calibration errors and achieve efficient scheduling of antenna calibration in a multi-node cooperation scenario.

[0076] Each radio frequency unit is composed according to the DMIMO networking technology. The radio frequency units are divided into at least two levels. The radio frequency units at the same level are clustered with the radio frequency unit at the upper level as the central reference node. The radio frequency unit that receives the calibration sequence is the central reference node. A cluster is composed of several radio frequency units that send calibration sequences and one radio frequency unit that receives the calibration sequence; and the radio frequency unit sends a calibration sequence to the radio frequency unit that receives the calibration sequence in the same cluster. Since the radio frequency units are clustered and calibrated level by level, the purpose of global calibration is achieved, and excessive calibration errors caused by the position dispersion of the radio frequency unit array with calibration relationships are avoided;

[0077] Further, to ensure the accuracy of the calibration sequence received between levels, the radio frequency units are divided into time domain stages according to the degree of inter-level interference. The radio frequency units at every other level within the stage simultaneously transmit calibration sequences to shorten the calibration cycle as much as possible, and the radio frequency units that simultaneously transmit calibration sequences are divided in the frequency domain to avoid interference.

[0078] Further, due to the time-frequency resource scheduling for antenna calibration considering calibration errors, the process of clustering radio frequency units and performing global calibration level by level can avoid excessive calibration errors caused by scattered positions of the radio frequency unit arrays with calibration relationships. The radio frequency units at every other level within the time domain stage simultaneously transmit calibration sequences to shorten the calibration cycle as much as possible, and the radio frequency units that simultaneously transmit calibration sequences are divided in the frequency domain to avoid interference. Therefore, it is possible to reuse as much time domain resources as possible on the basis of reducing calibration errors, and achieve efficient scheduling of antenna calibration in the scenario of multi-node cooperation. Brief Description of the Drawings

[0079] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0080] Figure 1 It is a schematic diagram of the implementation process of the time-frequency resource scheduling method for antenna calibration under DMIMO in the embodiment of the present invention;

[0081] Figure 2 It is a schematic diagram of the implementation process of the calibration sequence sending method in the embodiment of the present invention;

[0082] Figure 3 It is a schematic diagram of the implementation process of determining the calibration factor in the embodiment of the present invention;

[0083] Figure 4 It is a schematic diagram of the DMIMO system scenario in the embodiment of the present invention;

[0084] Figure 5 It is a schematic diagram of the transceiver of the calibration sequence within the time domain stage in the embodiment of the present invention;

[0085] Figure 6 It is a schematic diagram of the time domain stage division in the embodiment of the present invention;

[0086] Figure 7 It is the time-frequency resource scheduling system for antenna calibration under DMIMO in the embodiment of the present invention;

[0087] Figure 8 It is a schematic diagram of the radio frequency unit structure in the embodiment of the present invention;

[0088] Figure 9 It is a schematic diagram of the structure of the calibration sequence sending device in the embodiment of the present invention. Detailed implementation mode

[0089] The inventor noticed during the invention process that:

[0090] Channel reciprocity plays an important role in large-scale antenna systems that are mostly applied in the TDD (Time Division Duplex) mode. Although the uplink and downlink in the TDD mode are carried on the same frequency and generally considered to have the same physical channel gain, in actual circuits, both the transmission and reception processes of the channel need to go through the RF (Radio Frequency) link module. The RF links for each antenna's reception and transmission are completed by different circuits respectively, and it is very difficult to make the characteristics of the transmission and reception circuits exactly the same. In addition, due to the different environmental temperature, humidity and other characteristics of the transmission and reception circuits, the characteristics of the two sets of circuits cannot be made exactly the same, resulting in the impairment of channel reciprocity. Therefore, the antenna calibration technology for compensating the loss of channel reciprocity is particularly important for the DMIMO system.

[0091] Considering that the RF (Radio Frequency) link mismatch at the RF unit end has the greatest impact on the system performance and the calibration scheme using user feedback has extremely high overhead, antenna calibration between RF units in the DMIMO system is usually completed by the method of transmitting and receiving calibration sequences between RF units.

[0092] In the prior art, the mainstream scheme for global antenna calibration is to fix a reference RF unit and send a calibration sequence to the antenna to be calibrated. This scheme will cause extremely high calibration errors in the scenario where the positions of the DMIMO RF unit arrays are scattered.

[0093] In addition, the adjacent calibration scheme and the grouped calibration scheme using non-fixed reference RF units designed for distributed antenna arrays can reduce the error of each calibration, but as the number of nodes increases, their cumulative error and time complexity will increase.

[0094] Due to the large-scale cooperation in the DMIMO system, the number of stations increases, which puts higher requirements on both the antenna calibration period and the antenna calibration performance. Therefore, aiming at the problems of too high time complexity and too long calibration period in the prior art solutions, and considering the calibration error of the distributed antenna array when designing the antenna calibration scheme, the embodiment of the present invention proposes an antenna calibration time-frequency resource scheduling scheme considering calibration error, in which the RF units are clustered and calibrated step by step to achieve the purpose of global calibration, avoiding excessive calibration errors caused by the scattered positions of the RF unit arrays with calibration relationships; in order to ensure the accuracy of the inter-stage received calibration sequence, the RF units are divided in the time domain according to the degree of inter-stage interference. The RF units at every other level send calibration sequences simultaneously within the stage to shorten the calibration period as much as possible, and the RF units that send calibration sequences simultaneously are divided in the frequency domain to avoid interference.

[0095] The specific implementation manners of the present invention will be described below with reference to the accompanying drawings.

[0096] During the description process, the radio frequency unit for transmitting the calibration sequence and the radio frequency unit for receiving the calibration sequence will be involved respectively, and then examples of their cooperation will be given to better understand the implementation of the solution given in the embodiments of the present invention. Such a description method does not mean that the two must be implemented in cooperation or must be implemented separately. In fact, when the radio frequency unit for transmitting the calibration sequence and the radio frequency unit for receiving the calibration sequence are implemented separately, they also solve the problems on their own sides respectively, and when the two are used in combination, better technical effects will be obtained.

[0097] The following will be described from the perspective of the DMIMO system.

[0098] Figure 1 As shown in the schematic diagram of the implementation process of the time-frequency resource scheduling method for antenna calibration under DMIMO, it may include:

[0099] Step 101: Classify several radio frequency units within the cooperation range according to a predetermined rule, and cluster the radio frequency units at the same level with the radio frequency unit at the previous level as the central node;

[0100] Step 102: The radio frequency units within the cooperation range send and receive calibration sequences in a time-frequency domain scheduling manner between levels and clusters according to their division situations;

[0101] Step 103: Determine the range of radio frequency units for re-sending and receiving calibration sequences according to the interference degree of sending and receiving calibration sequences between levels, divide the calibration of radio frequency units within the cooperation range into time domain stages, and send and receive calibration sequences in the above-mentioned time-frequency domain scheduling manner between levels and clusters within the set time domain stages;

[0102] Step 104: Calculate the final calibration factor according to the radio frequency unit level.

[0103] Specifically, when performing time-frequency resource scheduling for antenna calibration under DMIMO, all radio frequency units within the cooperation range can be classified according to a certain rule, and the radio frequency units at the same level are clustered with the radio frequency unit at the previous level as the central node; the radio frequency units within the system send and receive calibration sequences in a time-frequency domain scheduling method between levels and clusters according to their division situations; determine the range of radio frequency units for re-sending and receiving calibration sequences according to the interference degree of sending and receiving calibration sequences between levels, so as to divide the calibration of radio frequency units within the system into time domain stages, and send and receive calibration sequences in the above-mentioned time-frequency domain scheduling method between levels and clusters within the set time domain stages; calculate the final calibration factor according to the radio frequency unit level.

[0104] In implementation, the classification of several radio frequency units within the cooperation range according to a predetermined rule includes:

[0105] Determine the central node within the collaboration range. Take this central node as the first-level node, form a cluster with the first-level node as the center, and obtain the first-level cluster.

[0106] Take the nodes within the cluster except the central node as the second-level nodes, form a cluster with the second-level nodes as the center and outside the first-level cluster, and obtain the second-level cluster.

[0107] Take the nodes within the cluster except the central node as the third-level nodes, and so on. The cluster with the nth-level nodes as the center and outside the (n - 1)th-level cluster is called the nth-level cluster, and the nodes within the cluster except the central node are the (n + 1)th-level nodes.

[0108] Specifically, when grading the RF units according to certain criteria, the central node within the collaboration range can be found. This central node is the first-level node. Form a cluster with the first-level node as the center, which is called the first-level cluster. The nodes within the cluster (except the center) are the second-level nodes. The cluster with the second-level nodes as the center and outside the first-level cluster is called the second-level cluster. The nodes within the cluster (except the center) are called the third-level nodes, and so on. The cluster with the nth-level nodes as the center and outside the (n - 1)th-level cluster is called the nth-level cluster, and the nodes within the cluster (except the center) are called the (n + 1)th-level nodes.

[0109] In implementation, determine the first-level node in the following way:

[0110] Take the center of the RF unit distribution area as the center of a circle, use the preset threshold as the radius to form a cluster, and then form a cluster with the RF units within the cluster as the center. Select the one with a higher number of RF units in each cluster as the first-level node within the collaboration range.

[0111] Specifically, when determining the criteria for selecting the central node, take the center of the RF unit distribution area as the center of a circle, use a certain threshold as the radius to form a cluster, and then form a cluster with the RF units within the cluster as the center. Select the one with a higher number of RF units in each cluster, which will be the first-level node within the collaboration range.

[0112] In implementation, determine the final calibration factor in the following way:

[0113] Within the cluster, use the central node of the cluster as the reference RF unit for antenna calibration. The calibration factor of this cluster is the product of the calibration factor within the cluster and the factor obtained by calibrating the central node of this cluster in the previous-level cluster.

[0114] Specifically, when using the central node of the cluster as the reference RF unit for antenna calibration within the cluster, the calibration factor of this cluster is related to the level of the cluster, that is, the calibration factor of this cluster is the product of the calibration factor within the cluster and the factor obtained by calibrating the central node of this cluster in the previous-level cluster.

[0115] In implementation, the time-domain scheduling methods between levels and between clusters include:

[0116] Transmit and receive calibration sequences at the same time slot at alternate levels.

[0117] Specifically, during inter-level and inter-cluster time-domain scheduling, calibration sequences can be transmitted and received at the same time slot with one level skipped.

[0118] In implementation, the inter-level and inter-cluster frequency-domain scheduling method includes:

[0119] When odd-level nodes send calibration sequences to even-level nodes, they are sent at different frequency points, and the number of frequency points used is determined according to the degree of even nodes. Conversely, calibration sequences are sent according to the same rule.

[0120] Specifically, during inter-level and inter-cluster frequency-domain scheduling, when odd-level nodes send calibration sequences to even-level nodes, they can be sent at different frequency points, and the number of frequency points used is determined according to the degree of even nodes. Conversely, calibration sequences are sent according to the same rule.

[0121] In implementation, the radio frequency units in the system are divided into time-domain phases according to the interference degree of sending and receiving calibration sequences between levels, including:

[0122] In a network divided into n-level clusters, starting from the second level for comparison, time-domain phase division is performed: the k-level node receives a calibration sequence and is interfered by signals from nodes such as the k-3 level or the k+3 level. If the signal-to-interference-plus-noise ratio of the received useful signal is lower than a preset threshold, the cluster where the useful signal is located is made to perform antenna calibration again in the next time domain phase; otherwise, the result of this calibration is used as the final calibration result of the cluster where the useful signal is located.

[0123] Specifically, when dividing the radio frequency units in the system into time-domain phases according to the interference degree of sending and receiving calibration sequences between levels, in a network that can be divided into n-level clusters, starting from the second level for comparison, time-domain phase division is performed: the k-level node receives a calibration sequence and is interfered by signals from nodes such as the k-3 level or the k+3 level. If the signal-to-interference-plus-noise ratio of the received useful signal is lower than a preset threshold, the cluster where the useful signal is located is made to perform antenna calibration again in the next time domain phase; otherwise, the result of this calibration is used as the final calibration result of the cluster where the useful signal is located.

[0124] The following is an explanation from the perspective of radio frequency units.

[0125] Figure 2 As shown in the figure, for the implementation process schematic diagram of the calibration sequence sending method, it can include:

[0126] Step 201: The radio frequency unit determines the calibration sequence to be transmitted and the radio frequency unit that receives the calibration sequence. Herein, each radio frequency unit is configured according to the DMIMO networking technology, and each radio frequency unit is divided into at least two levels. The radio frequency units at the same level are clustered with the upper-level radio frequency unit as the central reference node. The radio frequency unit that receives the calibration sequence is the central reference node, and several radio frequency units that send the calibration sequence and one radio frequency unit that receives the calibration sequence form a cluster.

[0127] Step 202: The radio frequency unit sends the calibration sequence to the radio frequency unit that receives the calibration sequence.

[0128] The time-frequency resource scheduling scheme for antenna calibration under DMIMO proposed in the embodiments of the present invention can include two stages as follows. However, this segmentation is for the convenience of understanding and does not mean that the technical solution provided by the embodiments of the present invention must be divided into two segments or have other meanings:

[0129] 1. Classify / cluster the radio frequency units according to certain rules:

[0130] In implementation, when classifying each radio frequency unit, it is classified according to the geographical location.

[0131] Specifically, to avoid too large a difference in the signal-to-noise ratio between the reference radio frequency unit and the calibration radio frequency unit, each radio frequency unit can be classified according to the geographical location, and the radio frequency units at the same level are clustered with the upper-level radio frequency unit as the central reference node.

[0132] 2. Perform time-frequency resource scheduling for sending the calibration sequence between radio frequency units:

[0133] In implementation, when the radio frequency units in the same cluster send the calibration sequence to the radio frequency unit that receives the calibration sequence, the frequency domain resources and / or time resources used are the same, and are different from those of other clusters and / or other classified radio frequency units.

[0134] Specifically, when the radio frequency unit sends and receives the calibration sequence, inter-level and inter-cluster time-frequency domain scheduling is performed, including that the radio frequency units at alternate levels simultaneously send the calibration sequence to the connection node to minimize the time complexity as much as possible. To avoid interference when sending sequences to the same node, the frequency domain is divided for the transmission of the calibration sequences of the upper-level reference node and the nodes within the same-level cluster connected to the node. In addition, to ensure the accuracy of inter-level calibration, the radio frequency units in the system are divided in the time domain according to the interference degree of sending and receiving the calibration sequence between levels, and thus the calibration sequence is resent.

[0135] Figure 3 As shown in the figure, the implementation process diagram for determining the calibration factor may include:

[0136] Step 301: Classify all radio frequency units within the cooperation range according to certain rules, and cluster them by adopting the strategy of using the radio frequency unit of the previous level as the central node for the same-level radio frequency units.

[0137] Specifically, determine the central reference node within the cooperation range, also known as the first-level node. The cluster where it is located can be called the first-level cluster, and the radio frequency units within the first-level cluster are called the second-level nodes. Furthermore, with the second-level nodes as the center, the nodes of the radio frequency units within this cluster and outside the first-level cluster are called the third-level nodes, and so on to divide the radio frequency units. The preset value of the cluster size can be adjusted according to the available frequency domain resources.

[0138] Step 302: According to the division of radio frequency units, perform time-frequency domain scheduling between levels and between clusters, including that the radio frequency units of every other level receive and send calibration sequences in different frequency domains in the same time slot.

[0139] Step 303: Determine the range of radio frequency units between levels that need to re-transmit and receive calibration sequences in the next time domain stage according to the degree of interference between levels, mainly considering the interference of radio frequency units with similar levels.

[0140] Step 304: The radio frequency units of each level included in the next time domain stage will use Steps 202 and 203 to re-transmit and receive the antenna calibration sequences.

[0141] Step 305: After the transmission and reception of the calibration sequences of the radio frequency units within the cooperation range are completed according to the time-frequency domain resource scheduling method, calculate the calibration factors, and determine the final calibration factors according to the radio frequency unit levels.

[0142] It can be seen from the above implementation that applying the existing centralized antenna calibration technology solution in a distributed large-scale antenna array will lead to excessive calibration errors. At the same time, in the existing distributed antenna calibration technology solutions, adjacent antenna calibration or grouped calibration will have too high time complexity in the scenario where the number of radio frequency units increases. The calibration sequence transmission scheme provided in the embodiments of the present invention considers the time-frequency resources scheduling of antenna calibration for calibration errors. The process of clustering radio frequency units and performing global calibration level by level can avoid excessive calibration errors caused by the dispersion of the positions of the radio frequency unit arrays with calibration relationships. The radio frequency units of every other level transmit calibration sequences simultaneously within the time domain stage, which can shorten the calibration cycle as much as possible, and perform frequency domain division on the radio frequency units that transmit calibration sequences simultaneously to avoid interference. Therefore, it can reuse time domain resources as much as possible on the basis of reducing calibration errors and achieve efficient scheduling of antenna calibration in the scenario of multi-node cooperation.

[0143] The following is an example for illustration.

[0144] To meet the stringent requirements for high performance in next-generation mobile communication systems, especially 5G networks, with the development of technology, distributed massive multiple-input multiple-output (DMIMO) technology has stood out among many candidate key technologies for 5G due to its advantages in enhancing coverage, increasing the rate of edge users, and eliminating indoor blind spots. Figure 4 Figure 2 shows a schematic diagram of the DMIMO system scenario, such as Figure 4 the scenario shown. In the actual scenario, the antenna calibration technology for compensating the loss of channel reciprocity is particularly important for DMIMO systems mostly applied in the TDD mode. To achieve efficient scheduling of antenna calibration while reducing calibration errors, an example will be given below.

[0145] 1. The system classifies all radio frequency (RF) units within the cooperation range according to certain rules and clusters them using the strategy of taking the upper-level RF unit as the central node for the same-level RF units.

[0146] In implementation, the highest-level RF unit is the RF unit in the cluster with the highest number of RF units in each cluster. Specifically, the criteria for selecting the central node can also include: taking the center of the RF unit distribution area as the center of a circle, a certain threshold as the radius to form a cluster, taking the RF units within the cluster as the center to form a cluster, and the one with a higher number of RF units in each cluster will be used as the first-level node within the cooperation range.

[0147] In the example, multiple RF units under the same baseband processing unit are distributed in a certain area. Taking the center of this area as the center of a circle and a certain preset value as the radius to form a cluster, the RF units within the cluster are used as candidate nodes for the central node. Then, taking the candidate nodes as the center of a circle and the same preset value as the radius to form a cluster, the one with a larger number of RF units within the cluster will become the central reference node within the cooperation range, also known as the first-level node, and the cluster where it is located can be called the first-level cluster. The RF units located in the first-level cluster are closest to the central reference node and have the lowest calibration error. Therefore, the more such RF units, the smaller the total error within the system. In addition, ensuring that the central node is basically located at the center of the cooperation area is beneficial to shortening the calibration cycle of the entire system in the subsequent process.

[0148] After the first-level node and the first-level cluster are determined, the RF units within the first-level cluster are called the second-level nodes. Then, taking the second-level nodes as the center and the same preset value as the radius to form a cluster, the nodes that are within this cluster and outside the first-level cluster are called the third-level nodes, and so on, dividing the RF units within the cooperation range into n levels.

[0149] In implementation, the preset value of the cluster radius for clustering is adjusted according to the number of frequency domain resources. Specifically, the preset value of the cluster radius can be adjusted according to the available number of frequency domain resources.

[0150] 2. According to the division of the radio frequency units, the calibration sequences are transmitted and received at intervals in the same time slot. Figure 5 It is a schematic diagram of the transmission and reception of the calibration sequence during the time domain stage, as Figure 5 shown. In the first time slot, the first-level node and the third-level node send the calibration sequence, and the second-level node and the fourth-level node receive the calibration sequence; in the second time slot, the first-level node and the third-level node receive the calibration sequence, and the second-level node and the fourth-level node send the calibration sequence, and vice versa, that is, the reception and transmission of the 4-level calibration sequence are completed within two time slots. Since there will be mutual interference when the k-level node and the k+2-level node send the calibration sequence to the k+1-level node, the k-level node and the k+2-level node that send the calibration sequence to the same k+1-level node will send the calibration sequence in different frequency domains.

[0151] 3. Determine the cluster radius of the clustering according to the interference degree of the inter-level transmission and reception of the calibration sequence.

[0152] Specifically, the radio frequency unit range for re-transmitting and receiving the calibration sequence can be determined according to the interference degree of the inter-level transmission and reception of the calibration sequence, so as to divide the radio frequency units in the system during the time domain stage.

[0153] In the example, the inter-level interference degree is determined by measuring the signal-to-interference-plus-noise ratio of the channels between the radio frequency units. The k-level node will use the calibration sequences sent by the k-1-level node and the k+1-level node as useful signals for antenna calibration, but at the same time, it will also receive interference from the k-3-level node or the k+3-level node. The k-1-level node and the k+1-level node send the calibration sequences in different frequency domains. When the k-3-level node or the k+3-level node sends the calibration sequences in these two frequency domains, it will cause a certain degree of interference. If the signal-to-interference-plus-noise ratio of the useful signal is higher than the preset value in the frequency domain where the k-level node receives the useful signal, it means that the k-3-level node or the k+3-level node does not interfere with the signal received by the k-level node, that is, the calibration result in this time domain stage can be used as the final calibration result of the cluster where the useful signal is located. On the contrary, when the signal-to-interference-plus-noise ratio of the useful signal is higher than the preset value, it means that the k-3-level node or the k+3-level node can interfere with the signal received by the k-level node, then the cluster where the useful signal is located will re-perform antenna calibration in the next time domain stage. Figure 6 It is a schematic diagram of the time domain stage division, as Figure 6 shown. In the first time domain stage, the fifth-level node and the third-level node send the calibration sequence in the same frequency domain, and the signal-to-interference-plus-noise ratio of the signal received by the sixth-level node from the fifth-level node is lower than the preset value, then the fifth-level cluster will re-perform antenna calibration in the second time domain stage.

[0154] 4. The radio frequency units at all levels included in the next time domain stage will re-transmit the antenna calibration sequence using the time-frequency domain scheduling scheme of 1 and 2.

[0155] 5. After the transmission and reception calibration sequences of the radio frequency units within the collaboration scope are completed, the calculation of the calibration factors is performed. The calibration factors of the radio frequency units are related to their levels, that is, the calibration factors of the radio frequency units are the product of the intra-cluster calibration factors and the factors obtained by the cluster center node through calibration at the upper-level cluster.

[0156] Based on the same inventive concept, embodiments of the present invention also provide a radio frequency unit, a calibration sequence transmission device, and a computer-readable storage medium. Since the principles of these devices for solving problems are similar to those of the calibration sequence transmission method, the implementation of these devices can refer to the implementation of the method, and the repeated parts will not be elaborated again.

[0157] When implementing the technical solutions provided by the embodiments of the present invention, it can be implemented in the following manner.

[0158] Figure 7 A time-frequency resource scheduling system for antenna calibration under DMIMO, including:

[0159] A hierarchical clustering module 701, configured to classify a plurality of radio frequency units within the collaboration scope according to a predetermined rule, and cluster the radio frequency units at the same level with the upper-level radio frequency unit as the center node;

[0160] A scheduling module 702, configured to perform the transmission and reception of calibration sequences for the radio frequency units within the collaboration scope in an inter-level and inter-cluster time-frequency domain scheduling manner according to their division situations;

[0161] A re-partitioning module 703, configured to determine the range of radio frequency units for re-transmitting and receiving calibration sequences according to the interference degree of the inter-level transmission and reception of calibration sequences, divide the calibration of the radio frequency units within the collaboration scope in the time domain stage, and perform the transmission and reception of calibration sequences in the above-mentioned inter-level and inter-cluster time-frequency domain scheduling manner within the set time domain stage;

[0162] A calibration factor calculation module 704, configured to calculate the final calibration factor according to the radio frequency unit level.

[0163] During implementation, the hierarchical clustering module is further configured to classify a plurality of radio frequency units within the collaboration scope according to a predetermined rule in the following manner:

[0164] Determine the center node within the collaboration scope, use this center node as the first-level node, and make a cluster with the first-level node as the center to obtain the first-level cluster;

[0165] Use the intra-cluster nodes except the center node as the second-level nodes, and make a cluster with the second-level nodes as the center and outside the first-level cluster to obtain the second-level cluster;

[0166] Taking the nodes within the cluster except the central node as the third-level nodes, and so on, the cluster centered on the nth-level nodes and outside the (n - 1)th-level cluster is called the nth-level cluster, and the nodes within the cluster except the central node are the (n + 1)th-level nodes.

[0167] In implementation, the hierarchical and clustering module is further used to determine the first-level nodes in the following way:

[0168] Taking the center of the radio frequency unit distribution area as the center of the circle and the preset threshold as the radius to form a cluster, and taking the radio frequency units within the cluster as the centers to form clusters. The one with a higher number of radio frequency units included in each cluster is used as the first-level nodes within the cooperation range.

[0169] In implementation, the calibration factor calculation module is further used to determine the final calibration factor in the following way:

[0170] Within the cluster, antenna calibration is performed with the central node of the cluster as the reference radio frequency unit. The calibration factor of the cluster is the product of the calibration factor within the cluster and the factor obtained by calibrating the central node of the cluster in the upper-level cluster.

[0171] In implementation, the scheduling module is further used to perform inter-level and inter-cluster time-domain scheduling in the following way:

[0172] Transmitting and receiving calibration sequences at the same time slot at every other level.

[0173] In implementation, the scheduling module is further used to perform inter-level and inter-cluster frequency-domain scheduling in the following way:

[0174] When odd-level nodes send calibration sequences to even-level nodes, they are sent at different frequency points, and the number of frequency points used is determined according to the degree of the even nodes. Conversely, calibration sequences are sent according to the same rule.

[0175] In implementation, the re-partitioning module is further used to perform time-domain stage partitioning on the radio frequency units within the system according to the interference degree of transmitting and receiving calibration sequences between levels in the following way:

[0176] In a network divided into n-level clusters, starting from the second level for comparison, time-domain stage partitioning is performed: the kth-level nodes receive calibration sequences and are interfered by signals from nodes such as the (k - 3)th-level or (k + 3)th-level nodes. If the signal-to-interference-plus-noise ratio of the received useful signal is lower than the preset threshold, the cluster where the useful signal is located is made to re-perform antenna calibration in the next time domain stage. Otherwise, the current calibration result is used as the final calibration result of the cluster where the useful signal is located.

[0177] Figure 8 It is a schematic diagram of the radio frequency unit structure. As shown in the figure, the radio frequency unit includes:

[0178] A processor 800, used to read the program in the memory 820 and execute the following processes:

[0179] Determine the calibration sequence to be sent and the radio frequency units that receive the calibration sequence. Among them, each radio frequency unit is composed according to the DMIMO networking technology, and each radio frequency unit is divided into at least two levels. The radio frequency units at the same level are clustered with the upper-level radio frequency unit as the central reference node. The radio frequency unit that receives the calibration sequence is the central reference node, and several radio frequency units that send the calibration sequence and a radio frequency unit that receives the calibration sequence form a cluster;

[0180] Send the calibration sequence to the radio frequency unit that receives the calibration sequence;

[0181] The transceiver 810 is used to receive and send data under the control of the processor 800.

[0182] In implementation, when each radio frequency unit is graded, it is graded according to the geographical location.

[0183] In implementation, when the radio frequency units in the same cluster send the calibration sequence to the radio frequency unit that receives the calibration sequence, the frequency domain resources and / or time resources used are the same, and are different from those of other clusters and / or radio frequency units at other levels.

[0184] In implementation, the preset value of the cluster radius of the cluster is adjusted according to the number of frequency domain resources.

[0185] In implementation, it further includes:

[0186] Determine the cluster radius of the cluster according to the interference degree of sending and receiving the calibration sequence between levels.

[0187] In implementation, the radio frequency units at the highest level are the radio frequency units in the cluster with the highest number of radio frequency units included in each cluster.

[0188] Among them, in Figure 8 The bus architecture can include any number of interconnected buses and bridges, specifically various circuits represented by one or more processors represented by the processor 800 and the memory represented by the memory 820 are linked together. The bus architecture can also link together various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art, so they will not be further described herein. The bus interface provides an interface. The transceiver 810 can be multiple components, that is, including a transmitter and a receiver, and provides a unit for communicating with various other devices on the transmission medium. The processor 800 is responsible for managing the bus architecture and general processing, and the memory 820 can store the data used by the processor 800 when performing operations.

[0189] Figure 9 For the structural schematic diagram of the calibration sequence sending device, as shown in the figure, it can include:

[0190] A determination module 901 is configured to determine a calibration sequence to be transmitted and a radio frequency unit for receiving the calibration sequence. Each radio frequency unit is formed according to the DMIMO networking technology, and each radio frequency unit is divided into at least two levels. The radio frequency units at the same level are clustered with the radio frequency unit at the previous level as the central reference node. The radio frequency unit for receiving the calibration sequence is the central reference node, and a cluster is formed by several radio frequency units for transmitting the calibration sequence and one radio frequency unit for receiving the calibration sequence.

[0191] A transmission module 902 is configured to transmit the calibration sequence to the radio frequency unit for receiving the calibration sequence.

[0192] In implementation, when the radio frequency units are classified, they are classified according to geographical locations.

[0193] In implementation, the transmission module is further configured that the radio frequency units in the same cluster use the same frequency domain resources and / or time resources when transmitting the calibration sequence to the radio frequency unit for receiving the calibration sequence, which are different from those of other clusters and / or radio frequency units at other levels.

[0194] In implementation, the preset value of the cluster radius of the clustering is adjusted according to the number of frequency domain resources.

[0195] In implementation, it further includes:

[0196] Determine the cluster radius of the clustering according to the interference degree of transmitting and receiving the calibration sequence between levels.

[0197] In implementation, the radio frequency unit at the highest level is the radio frequency unit in the cluster with the highest number of radio frequency units included in each cluster.

[0198] For the convenience of description, each part of the above-described device is described separately as various modules or units according to functions. Of course, when implementing the present invention, the functions of each module or unit can be implemented in the same or multiple software or hardware.

[0199] A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program for executing the above calibration sequence transmission method.

[0200] In specific implementation, reference can be made to the implementation of the calibration sequence transmission method.

[0201] For the convenience of description, each part of the above-described device is described separately as various modules or units according to functions. Of course, when implementing the present invention, the functions of each module or unit can be implemented in the same or multiple software or hardware.

[0202] In summary, in the technical solution provided by the embodiments of the present invention, all radio frequency units within the cooperation range are classified according to certain rules, and the radio frequency units at the same level use the radio frequency unit at the previous level as the central node for clustering; the radio frequency units in the system send and receive calibration sequences by means of inter-level and inter-cluster time-frequency domain scheduling methods according to their classification; the range of radio frequency units for re-sending and receiving calibration sequences is determined according to the interference degree of the inter-level sent and received calibration sequences, so as to divide the calibration of the radio frequency units in the system into a time domain stage, and send and receive calibration sequences by means of the above-mentioned inter-level and inter-cluster time-frequency domain scheduling scheme within the set time domain stage; the final calibration factor is calculated according to the radio frequency unit level.

[0203] Further, classifying radio frequency units according to certain criteria may further include: finding the central node within the cooperation range, which is the first-level node, clustering with the first-level node as the center, called the first-level cluster, the nodes within the cluster (except the center) are the second-level nodes, clustering with the second-level nodes as the center and outside the first-level cluster, called the second-level cluster, the nodes within the cluster (except the center) are called the third-level nodes, and so on. The cluster with the nth-level node as the center and outside the (n - 1)th-level cluster is called the nth-level cluster, and the nodes within the cluster (except the center) are called the (n + 1)th-level nodes.

[0204] Further, the criteria for selecting the central node may further include: taking the center of the radio frequency unit distribution area as the center of a circle and a certain threshold as the radius to make a cluster, clustering with the radio frequency units within the cluster as the center, and the one with a higher number of radio frequency units in each cluster will be used as the first-level node within the cooperation range. That is, the highest-level radio frequency units are the radio frequency units in the cluster with the highest number of radio frequency units in each sub-cluster.

[0205] Further, antenna calibration is performed within the cluster with the central node of the cluster as the reference radio frequency unit, and the calibration factor of the cluster is related to the level of the cluster, that is, the calibration factor of the cluster is the product of the in-cluster calibration factor and the factor obtained by calibrating the central node of the cluster in the previous-level cluster.

[0206] Further, the inter-level and inter-cluster time domain scheduling scheme may include: sending and receiving calibration sequences at the same time slot at intervals of one level.

[0207] Further, the inter-level and inter-cluster frequency domain scheduling scheme may include: when odd-level nodes send calibration sequences to even-level nodes, they are sent at different frequency points, and the number of frequency points used is determined according to the degree of even nodes. Conversely, calibration sequences are sent according to the same rule.

[0208] Further, the radio frequency units in the system can be divided into time domain stages according to the interference degree of the calibration sequence sent and received between levels, which may include: in a network that can be divided into n-level clusters, starting from the second level for comparison to perform time domain stage division: the k-th level node receives the calibration sequence and is interfered by the signals of nodes such as the (k - 3)-th level or the (k + 3)-th level. If the signal-to-interference-plus-noise ratio of the received useful signal is lower than the preset threshold, the cluster where the useful signal is located is commanded to perform antenna calibration again in the next time domain stage; otherwise, the current calibration result is used as the final calibration result of the cluster where the useful signal is located.

[0209] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) containing computer-usable program code.

[0210] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0211] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means, and the instruction means implements the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0212] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0213] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A time-frequency resource scheduling method for antenna calibration under DMIMO, characterized in that Including: Classify several radio frequency units within the cooperation range according to a predetermined rule, and cluster the radio frequency units at the same level with the radio frequency unit at the previous level as the central node; The radio frequency units within the cooperation range send and receive calibration sequences in an inter-level and inter-cluster time-frequency domain scheduling manner according to their division; Determine the range of radio frequency units for re-sending and receiving calibration sequences according to the interference degree of sending and receiving calibration sequences between levels, where the interference degree is determined according to the signal-to-interference-plus-noise ratio of the channels between radio frequency units; divide the calibration of radio frequency units within the cooperation range into time domain stages, and send and receive calibration sequences in the above-mentioned inter-level and inter-cluster time-frequency domain scheduling manner within the set time domain stages; where the inter-level and inter-cluster time-frequency domain scheduling manner includes: sending and receiving calibration sequences at the same time slot at every other level; or, when an odd-level node sends a calibration sequence to an even-level node, sending at different frequency points and determining the number of frequency points used according to the degree of the even node, and vice versa for sending calibration sequences according to the same rule; Calculate the final calibration factor according to the radio frequency unit level; where calculating the final calibration factor according to the radio frequency unit level includes: performing antenna calibration within the cluster with the cluster central node as the reference radio frequency unit, and the calibration factor is the product of the intra-cluster calibration factor and the calibration factor obtained by calibrating the cluster central node in the previous-level cluster.

2. The method according to claim 1, wherein The classifying several radio frequency units within the cooperation range according to a predetermined rule includes: Determine the central node within the cooperation range, use this central node as the first-level node, and make a cluster with the first-level node as the center to obtain the first-level cluster; Use the nodes within the cluster except the central node as the second-level nodes, and make a cluster with the second-level nodes as the center and outside the first-level cluster to obtain the second-level cluster; Use the nodes within the cluster except the central node as the third-level nodes, and so on. The cluster with the nth-level node as the center and outside the (n - 1)th-level cluster is called the nth-level cluster, and the nodes within the cluster except the central node are used as the (n + 1)th-level nodes.

3. The method according to claim 1 or 2, characterized in that, Determine the first-level node in the following manner: Make a cluster with the center of the radio frequency unit distribution area as the center and a preset threshold as the radius, and make a cluster with the radio frequency units within the cluster as the center. The one with a higher number of radio frequency units in each cluster is used as the first-level node within the cooperation range.

4. A time-frequency resource scheduling system for antenna calibration under DMIMO, characterized in that, Including: A hierarchical clustering module for classifying several radio frequency units within the cooperation range according to a predetermined rule and clustering the radio frequency units at the same level with the radio frequency unit at the previous level as the central node; A scheduling module for the radio frequency units within the cooperation range to send and receive calibration sequences in an inter-level and inter-cluster time-frequency domain scheduling manner according to their division; A re-partitioning module, configured to determine the radio frequency unit range for re-transmitting and receiving the calibration sequence according to the interference degree of the calibration sequence transmitted and received between levels, wherein the interference degree is determined according to the signal-to-interference-plus-noise ratio of the channels between radio frequency units; partition the calibration of radio frequency units within the cooperation range in the time domain phase, and transmit and receive the calibration sequence in the above-mentioned intra-level and inter-cluster time-frequency domain scheduling manner within the set time domain phase; wherein, the intra-level and inter-cluster time-frequency domain scheduling manner includes: transmitting and receiving the calibration sequence at the same time slot at intervals of levels; or, when an odd-level node transmits the calibration sequence to an even-level node, transmitting at different frequency points, and determining the number of frequency points used according to the degree of the even node, and vice versa for transmitting the calibration sequence according to the same rule. A calibration factor calculation module, configured to calculate the final calibration factor according to the radio frequency unit level; wherein, the final calibration factor is determined in the following manner: antenna calibration is performed within the cluster with the central node of the cluster as the reference radio frequency unit, and the calibration factor is the product of the intra-cluster calibration factor and the calibration factor obtained by calibrating the central node of the cluster at the previous level of the cluster.

5. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program for executing the method according to any one of claims 1 to 3.

Images