Communication method and related device

Abstract

The embodiment of the invention provides a communication method and a related device. The method comprises the following steps: sending first information indicating a first group of reference channels related to a first environment parameter set to user equipment; and sending second information related to the first environment parameter set to the user equipment, wherein the second information is used for determining one or more reference channels from the first group of reference channels. In the application, a central device can inform a user equipment of which environment parameter set is related by sending the second information, and help the user equipment determine at least one reference channel from a group of reference channels related to the environment parameter set indicated by the second information. According to the technical scheme, the validity of the reference channel which comes from the user equipment and is influenced by the environment parameter set can be ensured. Furthermore, the central device can determine the information related to the first DL channel without sending the channel measurement of the first DL channel, which can solve the problem of large signaling overhead caused by sending the channel measurement.

Description

Cross Reference to Related Applications

[0001] This application is related to U.S. Provisional Patent Application Serial No. 63 / 507,217, filed on June 9, 2023, entitled “Adaptive Update Method for Spatial Reference Channel of MU-MIMO Pairing,” the priority of which is claimed.

[0002] The entire disclosure of the above application is incorporated herein by reference. TECHNICAL FIELD

[0003] Embodiments of the present application relate to the field of communication technology, and more particularly, to a communication method and related apparatus. BACKGROUND

[0004] Multiple-input-multiple-output (MIMO) technology has been widely applied in modern wireless systems, which improves system capacity and bandwidth efficiency by exploiting spatial diversity among antenna ports. In order to fully utilize spatial resources and improve wireless throughput, multi-user multiple-input-multiple-output (MU-MIMO) deployment has been promoted. MU-MIMO requires pairing between a base station (BS) and multiple user devices (UEs) on the downlink (DL) channel. It is not feasible for each UE to report its DL channel estimation results to the BS, because the high-dimensional characteristics of the MU-MIMO channel result in a huge signaling overhead for DL feedback.

[0005] In fourth generation (4G) and fifth generation (5G) systems, it is assumed that the DL channel between a BS and a UE can be approximated to the uplink (UL) channel between the BS and the UE. The UE sends its reference signal to the BS so that the BS estimates the UL channel of the UE and uses the UL channel estimation as the DL channel estimation. However, radio frequency (RF) and infrared frequency (IF) components (e.g., analog circuits) usually do not have the UL / DL reciprocity assumption. Therefore, this assumption will inevitably impair the overall performance of the communication system. SUMMARY

[0006] Embodiments of the present application provide a communication method and related apparatus. These technical solutions can enable a center device to determine the information of a DL channel of a user device without sending channel measurements of the DL channel related to specific channel conditions.

[0007] According to a first aspect, embodiments of the present application provide a communication method, which can be performed by a center device. The method comprises: sending, to a user device, first information indicating a first set of reference channels related to a first set of environment parameters; and sending, to the user device, second information related to the first set of environment parameters, the second information being used to determine one or more first reference channels from the first set of reference channels.

[0008] According to a second aspect, embodiments of the present application provide a communication method, which can be performed by a user device. The method comprises: receiving, from a center device, first information indicating a first set of reference channels related to a first set of environment parameters; and receiving, from the center device, second information related to the first set of environment parameters, the second information being used to determine one or more first reference channels from the first set of reference channels.

[0009] In some implementations, a distance between any one of the one or more reference channels and a DL channel of the user device is less than or equal to a first threshold.

[0010] A set of environment parameters represents a channel condition.

[0011] The center device can inform the user device which set of environment parameters the second information is related to, and help the user device to determine at least one reference channel from a set of reference channels related to the set of environment parameters indicated by the second information. The above technical solution can ensure the effectiveness of the reference channels from the user device that are affected by the set of environment parameters. In addition, the center device does not need to send channel measurements of the DL channel of the user device to determine the reference channels related to the first set of environment parameters, which can reduce the signaling overhead of sending the DL channel measurements.

[0012] With reference to the first aspect or the second aspect, in some embodiments, the second information indicates one or more of a first pilot pattern, a first compression function, a first scoring function, and a first threshold; the first compression function is used to determine one or more of: one or more reference channels in the first set of reference channels and a channel measurement of a first DL channel of the user device; the first scoring function is used to determine a distance between the first DL channel and one reference channel in the first set of reference channels; and the first threshold is used to determine the one or more reference channels in the first set of reference channels.

[0013] The one or more of the first pilot pattern, the first compression function, the first scoring function, and the first threshold can be related to the first set of environment parameters. When the center device is related to multiple sets of environment parameters, the center device can inform the user device to use which pilot pattern, compression function, scoring function, or / and first threshold to determine the first reference channel.

[0014] With reference to the first aspect or the second aspect, in some embodiments, the method further comprises: sending or receiving third information related to the second set of environmental parameters, the third information indicating one or more of the second pilot pattern and the second compression function; the second compression function being used to determine one or more of: one or more reference channels in the set of reference channels, and a channel measurement of a second DL channel of the user equipment.

[0015] The second DL channel can be the same as the first DL channel. The “first DL channel” and “second DL channel” in the following description are named only for distinction, and do not limit the protection scope of the embodiments of the present application.

[0016] The central device can be related to the first set of environmental parameters and the second set of environmental parameters, the set of reference channels, the scoring function and the threshold related to the second set of environmental parameters being the same as those related to the first set of environmental parameters. Therefore, sending only the second pilot pattern and / or the second compression function can reduce the signaling overhead.

[0017] With reference to the first aspect or the second aspect, in some embodiments, the second set of environmental parameters comprises the first set of environmental parameters; the second pilot pattern indicates a part that changes between a pilot pattern related to the first set of environmental parameters and a pilot pattern related to the second set of environmental parameters; and the second compression function indicates a part that changes between a compression function related to the first set of environmental parameters and a compression function related to the second set of environmental parameters.

[0018] Sending only the part that changes in the pilot pattern and / or the compression function can further reduce the signaling overhead.

[0019] With reference to the first aspect, in some embodiments, sending the third information related to the second set of environmental parameters to the user equipment comprises any one of: sending the third information to the user equipment upon determining that the channel condition changes from a first channel condition to a second channel condition, the first channel condition being related to the first set of environmental parameters, and the second channel condition being related to the second environment; sending the third information to the user equipment when it is determined that the current channel condition comprises the first channel condition and the second channel condition; or sending the third information to the user equipment when it is estimated or predicted that the channel condition of the user equipment changes from the first channel condition to the second channel condition.

[0020] The set of environmental parameters related to the central device or the user device can change frequently. Updating the information related to the set of environmental parameters, such as the pilot pattern and the compression function, when the set of environmental parameters is determined to change, or sending the information related to the second set of environmental parameters when the central device is determined to be related to both the first set of environmental parameters and the second set of environmental parameters, can ensure the validity of the reference channel related to the set of environmental parameters from the user device. For example, it can be avoided that the user device still reports the reference channel related to the first set of environmental parameters when the set of environmental parameters related to the central device has changed to the second set of environmental parameters.

[0021] With reference to the first aspect or the second aspect, in some embodiments, the method further comprises sending or receiving fourth information indicating a second set of reference channels related to the second set of environmental parameters.

[0022] The set of reference channels related to the second set of environmental parameters can be different from the set of reference channels related to the first set of environmental parameters. Therefore, updating the set of reference channels can ensure the validity of the reference channel related to the set of environmental parameters from the user device.

[0023] With reference to the first aspect or the second aspect, in some embodiments, the third information further indicates one or more of a second scoring function or a second threshold value; the second scoring function is used to determine a distance between the DL channel of the user device and one of the second set of reference channels; the second threshold value is used to determine one or more of the second set of reference channels.

[0024] The second threshold value can be the same as the first threshold value.

[0025] The scoring function and / or the threshold value are related to the set of environmental parameters. Therefore, when the set of environmental parameters changes, the central device can inform the user device which scoring function and / or threshold value should be used, which can ensure the validity of the reference channel from the user device.

[0026] With reference to the first aspect or the second aspect, in some embodiments, the method further comprises receiving or sending fifth information indicating a first reference channel, a distance between the first reference channel and the DL channel of the user device is less than or equal to a third threshold value, and the one or more of the first set of reference channels comprises the first reference channel.

[0027] The third threshold value can be the same as the first threshold value or the second threshold value. The DL channel can be the same as the first DL channel, or the DL channel can be the same as the second DL channel.

[0028] In some implementations, the first reference channel is determined according to the first scoring function and the first threshold value.

[0029] In some implementations, the first reference channel is determined according to a second scoring function and a second threshold.

[0030] In some implementations, the reference channels reported by the user equipment can be used for user equipment pairing. Two user equipments cannot be paired if one reports at least one reference channel in a first set of reference channels and the other reports at least one reference channel in a second set of reference channels. User equipments reporting reference channels in the same set of reference channels can be paired and can be considered as candidate user equipments from which user equipments for pairing are selected.

[0031] The center device can determine information related to the DL channel without sending channel measurement of the DL channel. If the set of environment parameters related to the center device includes both the first set of environment parameters and the second set of environment parameters, the center device, upon receiving the fifth information, will determine a candidate user equipment related to the first set of environment parameters to select a user equipment to pair with the user equipment.

[0032] With reference to the first aspect or the second aspect, in some embodiments, the method further comprises receiving or sending sixth information indicating a second reference channel in the second set of reference channels, wherein a distance between the second reference channel and the DL channel of the user equipment is less than or equal to a fourth threshold.

[0033] The fourth threshold can be the same as the second threshold. The DL channel can be the same as the first DL channel, or the DL channel can be the same as the second DL channel.

[0034] In some implementations, the second reference channel is determined according to a second scoring function and a second threshold.

[0035] The first set of environment parameters can be related to a first set of candidate user equipments, and the second set of environment parameters can be related to a second set of candidate user equipments. The center device needs to determine which set of candidate user equipments to use to select a user equipment to pair with the user equipment.

[0036] If the set of environment parameters related to the center device has changed to the second set of environment parameters, or the set of environment parameters related to the center device includes both the first set of environment parameters and the second set of environment parameters, upon receiving the sixth information, the center device will determine a set of candidate user equipments related to the second set of environment parameters to select a user equipment to pair with the user equipment.

[0037] With reference to the first aspect or the second aspect, in some embodiments, a distance between the second reference channel and the DL channel is less than a distance between any reference channel in the first set of reference channels and the DL channel.

[0038] When the set of environment parameters related to the central device includes both the first set of environment parameters and the second set of environment parameters, the user device can report the reference channel closer to the DL channel, so that the central device does not need to determine which one is closer, which can reduce the computational complexity of the central device when selecting the user device for pairing.

[0039] With reference to the first aspect or the second aspect, in some embodiments, the method further includes: receiving or sending seventh information indicating a first distance between a reference channel in the first set of reference channels and the DL channel and eighth information indicating a second distance between a reference channel in the second set of reference channels and the DL channel; the first distance and the second distance are used to determine the set of environment parameters for user device pairing from the first set of environment parameters and the second set of environment parameters.

[0040] If the set of environment parameters related to the central device includes both the first set of environment parameters and the second set of environment parameters, the user device can report the first distance and the second distance when reporting the reference channel in the first set of reference channels and the reference channel in the second set of reference channels at the same time, so that the central device can determine the closer reference channel. This technical solution can reduce the computational complexity of the user device.

[0041] With reference to the first aspect or the second aspect, in some embodiments, the first set of reference channels is determined according to the position of the user device or the channel condition related to the user device.

[0042] Determining the first set of reference channels based on the position of the user device related to the channel condition of the user device can reduce the number of reference channels in the first set of reference channels, which can reduce the signaling overhead for sending the first set of reference channels.

[0043] According to the third aspect, embodiments of the present application provide a communication method, which can be performed by a user device. The method includes: receiving, from a central device, first information indicating a first set of reference channels related to a first set of environment parameters; determining whether a distance between a first reference channel in the first set of reference channels and a DL channel of the user device is less than or equal to a first threshold value.

[0044] The detailed description of the beneficial effects of the above-mentioned third aspect and other possible implementation manners of the third aspect is described above in the first aspect and the second aspect.

[0045] With reference to the third aspect, in some embodiments, the method further includes: receiving, from the central device, fourth information indicating a second set of reference channels related to a second set of environment parameters; determining whether a distance between a second reference channel in the second set of reference channels and the DL channel of the user device is less than or equal to a second threshold value.

[0046] With reference to the third aspect, in some embodiments, a first reference channel in the first group of reference channels is closer to the DL channel than the first threshold, and none of the second group of reference channels is closer to the DL channel than the second threshold; the method further comprises sending, to the central device, fifth information indicating the first reference channel.

[0047] With reference to the third aspect, in some embodiments, a second reference channel in the second group of reference channels is closer to the DL channel than the second threshold, and none of the first group of reference channels is closer to the DL channel than the first threshold; the method further comprises sending, to the central device, sixth information indicating the second reference channel.

[0048] With reference to the third aspect, in some embodiments, a first reference channel in the first group of reference channels is closer to the DL channel than the first threshold, and a second reference channel in the second group of reference channels is closer to the DL channel than the second threshold; the method further comprises sending, to the central device, ninth information indicating the reference channel that is closer to the DL channel among the first reference channel and the second reference channel.

[0049] With reference to the third aspect, in some embodiments, a first reference channel in the first group of reference channels has a first distance to the DL channel that is less than or equal to the first threshold, and a second reference channel in the second group of reference channels has a second distance to the DL channel that is less than or equal to the second threshold; the method further comprises sending, to the central device, tenth information indicating the first reference channel and the second reference channel.

[0050] With reference to the third aspect, in some embodiments, the method further comprises sending, to the central device, eleventh information indicating the first distance and the second distance.

[0051] According to a fourth aspect, a communication device is provided. The communication device comprises functions or units for performing the method according to the first aspect or any possible embodiment of the first aspect.

[0052] According to a fifth aspect, a communication device is provided. The communication device comprises functions or units for performing the method according to the first aspect or any possible embodiment of the first aspect, the second aspect or any possible embodiment of the second aspect, the fourth aspect or any possible embodiment of the fourth aspect.

[0053] According to a sixth aspect, a system is provided. The system comprises a communication device according to the fifth aspect and a communication device according to the sixth aspect.

[0054] According to a seventh aspect, a communication apparatus is provided. The communication apparatus comprises a processor and a communication interface. The processor is connected to the communication interface. The processor is configured to execute one or more instructions, and the communication interface is configured to communicate with other network elements under control of the processor. The processor is configured to execute a method according to any one of the following: the first aspect or the possible implementation manners of the first aspect; the second aspect or the possible implementation manners of the second aspect; or the third aspect or the possible implementation manners of the third aspect.

[0055] According to an eighth aspect, a communication apparatus is provided. The communication apparatus comprises at least one processor coupled with at least one memory. The at least one memory is configured to store a computer program or one or more instructions. The at least one processor is configured to: invoke and run the computer program or the one or more instructions from the at least one memory, so as to cause the communication apparatus to execute a method according to any one of the following: the first aspect or the possible implementation manners of the first aspect; the second aspect or the possible implementation manners of the second aspect; or the third aspect or the possible implementation manners of the third aspect.

[0056] According to a ninth aspect, a computer storage medium is provided. The computer storage medium stores program codes for executing one or more instructions of a method according to any one of the following: the first aspect or any possible implementation manners of the first aspect; the second aspect or any possible implementation manners of the second aspect; or the third aspect or the possible implementation manners of the third aspect.

[0057] According to a tenth aspect, the present application provides a computer program product comprising one or more instructions, when the computer program product is run on a computer, the computer executes a method according to any one of the following: the first aspect or any possible implementation manners of the first aspect; the second aspect or any possible implementation manners of the second aspect; or the third aspect or the possible implementation manners of the third aspect. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 is a schematic diagram of a communication system.

[0059] Figure 2 An example communication system is shown.

[0060] Figure 3 Another example of an ED and a base station is shown.

[0061] Figure 4 is an example of a channel model of a MIMO system.

[0062] Figure 5 is a schematic flowchart of a communication method according to an embodiment of the present application.

[0063] Figure 6is a schematic flow chart of another communication method of embodiments of the present application.

[0064] Figure 7 is a schematic diagram of vectorization of MIMO channel data samples formed as tensors.

[0065] Figure 8 is a schematic diagram of juxtaposing column-wise vectorized channel data samples into a matrix .

[0066] Figure 9 is a schematic flow chart of yet another communication method of embodiments of the present application.

[0067] Figure 10 is a schematic diagram of an equivalent low-dimensional space of a channel spatial basis representation.

[0068] Figure 11 is a schematic diagram of approximating a channel spatial basis by a DNN implementation.

[0069] Figure 12 is a schematic diagram of compressing a reference channel to a low-dimensional space.

[0070] Figure 13 is a schematic flow chart of still another communication method of embodiments of the present application.

[0071] Figure 14 is a schematic diagram of a pilot pattern.

[0072] Figure 15 is a schematic diagram of a channel spatial basis transform.

[0073] Figure 16 is a schematic flow chart of still another communication method of embodiments of the present application.

[0074] Figure 17 is a schematic diagram of a scoring function that measures distance in an equivalent low-dimensional space.

[0075] Figure 18 is a schematic diagram of another scoring function that measures distance in an equivalent low-dimensional space.

[0076] Figure 19 is a schematic diagram of a communication method of embodiments of the present application.

[0077] Figure 20 is a schematic diagram of another communication method of embodiments of the present application.

[0078] Figure 21 is a schematic diagram of yet another communication method of embodiments of the present application.

[0079] Figure 22 is a schematic diagram of an example of a selected portion of a set of reference channels.

[0080] Figure 23 is a schematic illustration of a set of environmental parameters that a central device can be involved with.

[0081] Figure 24 is another schematic illustration of a set of environmental parameters that a central device can be involved with.

[0082] Figure 25 is yet another schematic illustration of a set of environmental parameters that a central device can be involved with.

[0083] Figures 26 to 31 is a schematic illustration of a communication method of embodiments of the application.

[0084] Figures 32 to 33 is a schematic block diagram of a possible device of embodiments of the application.

[0085] Figure 34 is a schematic illustration of UL and DL coverage range disparity caused by Tx power from BS and UE.

[0086] Figure 35 is a schematic illustration of terabit multiple-input-multiple-output (T-MIMO) channel dimensionality.

[0087] Figures 36 to 41 is a schematic flowchart of a communication method of embodiments of the application.

[0088] Figure 42 shows units or modules in a device. DETAILED DESCRIPTION

[0089] Unless otherwise noted, or the context indicates otherwise, the following terms and phrases have the meanings provided below.

[0090] (1) Central device and user equipment A wireless system can include one central device and multiple user devices. The central device can be a BS, a base transceiver station (BTS), a radio base station, a network node, a network device, a network-side device, a transmission / reception node, a Node B, an evolved Node B (eNodeB or eNB), a Home eNodeB, a next Generation NodeB (gNB), a transmission point (TP), a site controller, an access point (AP) or a wireless router, a relay, a remote radio head, a ground node, a ground network device or a ground base station, a base band unit (BBU), a remote radio unit (RRU), an active antenna unit (AAU), a remote radio head (RRH), a central unit (CU), a distribute unit (DU), a positioning node, or a device (e.g., a communication module, a modem, or a chip) in the above devices, among other possibilities; and the user device can include such devices (or can be referred to as): a user equipment (UE), a wireless transmit / receive unit (WTRU), a mobile station, a fixed or mobile subscriber unit, a cellular phone, a station (STA), a machine type communication (MTC) device, a personal digital assistant (PDA), a smartphone, a laptop, a computer, a tablet, a wireless sensor, a consumer electronics device, a smartbook, a vehicle, a car, a truck, a bus, a train, or an IoT device, an industrial device, or a device (e.g., a communication module, a modem, or a chip) in the above devices, among other possibilities. In a wireless system, a user device is connected to a central device in a wireless manner including a downlink (DL) in which the central device transmits a signal to the user device and an UL in which the user device transmits a signal to the central device. Both the DL and the UL transmit a signal through a wireless channel.

[0091] (2) Wireless channel A wireless channel can be a result of a multipath fading channel, which is affected by the surrounding environment to different degrees. A radio ray or a cluster (or group) of radio rays (or beams) of a wireless channel can be affected by the reflection and diffraction of radio waves or electromagnetic waves by surrounding physical surfaces, edges, or corners, such as buildings, roads, buses, tracks, people, etc., which can form multiple wireless paths at the receiving device side. Some surfaces, edges, and corners are fixed (e.g., buildings, bridges, utility poles, roads, sidewalks), while others are moving (e.g., moving vehicles), which can cause timing variations (fading) of multiple wireless paths. In practice, most moving entities can follow a certain trajectory at a certain speed (e.g., vehicles driving on a road), which can also be constrained by the surrounding environment composed of some fixed entities. Therefore, a wireless channel can be closely related to the surrounding environment in which it is located.

[0092] (3) Set of environmental parameters The set of environmental parameters can be a broad definition including, but not limited to, at least one of the following: a spatial region, a frequency band, a duplex mode (e.g., time division duplex or frequency division duplex; half duplex or full duplex), a time or duration, a precoder, a weather, and a data traffic (e.g., a traffic mode or a non-traffic mode. The traffic mode refers to a time period in which the data traffic exceeds a certain threshold. The non-traffic mode refers to a time period in which the data traffic is less than or equal to a certain threshold). In some implementations, the spatial region can indicate a region related to the space domain.

[0093] The difference between two sets of environmental parameters can be caused by at least one of the spatial region, the frequency band, the duplex mode, the time or duration, or the precoder. The set of environmental parameters can represent a channel condition or a wireless environment, and the change of the set of environmental parameters can cause the change of the channel condition or the wireless environment. The device related to the set of environmental parameters or the set of environmental parameters related to the device can be understood as that the device is in or will be in a certain wireless environment, or the device can transmit and receive information under a certain channel condition corresponding to the set of environmental parameters.

[0094] (4) Channel data sample The channel data sample can be measured and / or accumulated by the user equipment and / or the central device located in a certain wireless environment represented by the set of environmental parameters. A set of channel data samples can contain a plurality of wireless channel data samples, which can include one or more of channel states, channel measurements, channel coefficients, etc. A set of channel data samples can also be referred to as a data sample set or a learning data set or a training data set. The channel data sample can be in the form of a matrix or a tensor, a fixed vectorization order can be applied to all channel data samples, and the vectorization order can be saved or remembered.

[0095] (5) Reference channel The reference channel can be used to indicate a wireless channel that can exist in a certain wireless environment where the central device and the plurality of user devices are located, and the wireless environment can be represented by a set of environment parameters. The reference channel can be a virtual wireless channel related to a set of environment parameters, or a channel data sample selected from channel data samples. The reference channel can also be referred to as an anchor channel or a mooring channel.

[0096] The reference channel can be considered as data or information of a channel that can exist between the central device and the user devices. The reference channel is not a channel used to transmit information.

[0097] (6) Distance between two channels The distance between two channels can be understood in this application as the similarity or correlation between the two channels. The two channels can include two reference channels, or the two channels can include a DL channel and a reference channel.

[0098] (7) Common information related to a set of environment parameters The plurality of wireless channels can share the same channel condition or the same wireless environment, and therefore, the plurality of wireless channels will share some commonality related to the same set of environment parameters. The commonality can be considered as common information of the wireless channel related to the set of environment parameters. The common information can also be referred to as environment prior knowledge of the wireless channel related to the set of environment parameters.

[0099] The common information of the number of wireless channels between the central device and the plurality of user devices related to the set of environment parameters can be learned or obtained. The common information related to the set of environment parameters can be valid, persistent and useful for the wireless channel. The wireless channel is between the central device and the user devices entering the wireless environment represented by the set of environment parameters after the common information is obtained. Therefore, the common information can represent the commonality that is spatially and temporally persistent related to the set of environment parameters.

[0100] The common information related to the set of environment parameters can be determined by a plurality of channel data samples measured and / or accumulated in the wireless environment represented by the set of environment parameters.

[0101] A central device can have multiple pieces of common information, and each piece of common information is related to a set of environment parameters. For example, the sets of environment parameters can overlap or not overlap in a spatial region; or the sets of environment parameters can overlap or not overlap between UL and DL; or the sets of environment parameters can overlap or not overlap between wireless frequency bands.

[0102] The common information can be used to compress the reference channel or channel measurement. The common information can also be used by the user devices to determine information of the DL channel. The information of the DL channel includes information indicating one or more reference channels having sufficient similarity with the DL channel.

[0103] (8) User equipment pairing User equipment pairing is a process of selecting at least two user equipments for spatial multiplexing transmission on the same wireless time-frequency resource. User equipment pairing can also be referred to as user equipment grouping.

[0104] The technical terms such as “reference channel”, “environment parameter set”, “channel data sample”, “distance”, “common information” and “user equipment pairing” are not limited to the specific example names given herein; these terms or the concepts referred to by these terms can also be adopted with other names.

[0105] The technical solutions in the present application will be described below with reference to the accompanying drawings.

[0106] The technical solutions of the embodiments of the present application can be applied in various communication systems, for example, Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA) system, Wideband Code Division Multiple Access (WCDMA) system, general packet radio service (GPRS) system, Long Term Evolution (LTE) system, LTE frequency division duplex (FDD) system, LTE time division duplex (TDD) system, Universal Mobile Telecommunications System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX) communication system, wireless local area network (WLAN), fifth generation (5G) wireless communication system, new radio (NR) wireless communication system, sixth generation (6G) wireless communication system or other evolved communication system.

[0107] In order to facilitate the understanding of the embodiments of the present application, first, taking the communication system shown in Figures 1 to 3 as an example, the communication system to which the embodiments of the present application are applicable is described in detail.

[0108] ReferenceFigure 1 As a non-limiting illustrative example, a simplified schematic diagram of a communication system is provided. The communication system 100 includes a wireless access network 120. The wireless access network 120 can be a next generation (e.g., sixth generation (6G) or beyond) wireless access network, or a legacy (e.g., 5G, 4G, 3G, or 2G) wireless access network. One or more communication electric devices (EDs) 110a-110j (generally referred to as 110) can be interconnected to one another or to one or more network nodes (170a, 170b, generally referred to as 170) in the wireless access network 120. A core network 130 can be part of the communication system, and can be dependent or independent of the radio access technology used in the communication system 100. In addition, the communication system 100 includes a public switched telephone network (PSTN) 140, the Internet 150, and other networks 160.

[0109] Figure 2 An example communication system 100 is shown. Generally, the communication system 100 is capable of transmitting data and other content among a plurality of wireless or wireline elements. The communication system 100 can be designed to provide voice, data, video, and / or text content, among other content, through broadcast, multicast, and unicast, among other techniques. The communication system 100 can operate through sharing of resources, such as carrier frequency spectrum bandwidth, among its constituent elements. The communication system 100 can include a terrestrial communication system and / or a non-terrestrial communication system. The communication system 100 can provide a wide range of communication services and applications (e.g., earth monitoring, remote sensing, passive sensing and positioning, navigation and tracking, automated delivery and mobility, among others). The communication system 100 can provide a high level of availability and robustness through joint operation of terrestrial and non-terrestrial communication systems. For example, integration of non-terrestrial communication systems (or components thereof) into a terrestrial communication system can enable a heterogeneous network comprising multiple tiers. The heterogeneous network can achieve better overall performance compared to legacy communication networks through efficient multi-link joint operation, more flexible function sharing, and faster physical layer link switching between terrestrial and non-terrestrial networks.

[0110] The ground communication system and the non-terrestrial communication system can be considered as subsystems of a communication system. In the illustrated example, the communication system 100 includes electronic devices (EDs) 110a-110d (generally referred to as EDs 110), radio access networks (RANs) 120a and 120b, a non-terrestrial communication network 120c, a core network 130, a public switched telephone network (PSTN) 140, the Internet 150, and other networks 160. The RANs 120a and 120b include respective base stations (BSs) 170a and 170b, which can be generally referred to as terrestrial transmit and receive points (T-TRPs) 170a and 170b. The non-terrestrial communication network 120c includes an access node 120c, which can be generally referred to as a non-terrestrial transmit and receive point (NT-TRP) 172.

[0111] Alternatively or additionally, any of the EDs 110 can be configured to connect with, access, or communicate with any other T-TRPs 170a and 170b, NT-TRP 172, the Internet 150, the core network 130, the PSTN 140, the other networks 160, or any combination of the above. In some examples, the ED 110a can communicate uplink and / or downlink transmissions with the T-TRP 170a through an interface 190a. In some examples, the ED 110a, the ED 110b, and the ED 110d can also communicate directly with each other through one or more sidelink air interfaces 190b. In some examples, the ED 110d can communicate uplink and / or downlink transmissions with the NT-TRP 172 through an interface 190c.

[0112] The air interfaces 190a and 190b can use similar communication techniques, for example, any applicable wireless access techniques. For example, the communication system 100 can implement one or more channel access methods in the air interfaces 190a and 190b, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), or single-carrier FDMA (SC-FDMA), among other techniques. The air interfaces 190a and 190b can utilize other higher-dimensional signal spaces, which can involve combinations of orthogonal and non-orthogonal dimensions.

[0113] The air interface 190c can enable communication between the ED 110d and one or more NT-TRPs 172 over a wireless link or simply a link. In some examples, the link is a dedicated connection for unicast transmission, a connection for broadcast transmission, or a connection between a group of EDs and one or more NT-TRPs for groupcast transmission.

[0114] The RANs 120a and 120b are in communication with the core network 130 to provide the EDs 110a, 110b, and 110c with access to various services, such as voice, data, and other services. The RANs 120a and 120b and / or the core network 130 can be in direct or indirect communication with one or more other RANs (not shown) that can or can not be of the same type as the RANs 120a and 120b, and that can or can not be in direct communication with one another via the core network 130. The core network 130 can also serve as a gateway for the RANs 120a and 120b or EDs 110a, 110b, and 110c or both, to other networks (for example, the PSTN 140, the Internet 150, and the other networks 160) via the appropriate interfaces. In addition, some or all of the EDs 110a, 110b, and 110c can include functionality for communicating over different wireless links using different wireless technologies and / or protocols, and for communicating with different wireless networks. The EDs 110a, 110b, and 110c can communicate with service providers or switches (not shown) and with the Internet 150 through wired communication channels, rather than or in addition to wireless communication. The PSTN 140 can include a circuit- switched telephone network that provides plain old telephone service (POTS). The Internet 150 can include a network of computers and / or sub-networks (intranets) and incorporate protocols such as the Internet Protocol (IP), the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the like. The EDs 110a, 110b, and 110c can be multi-mode devices capable of operating according to multiple wireless access technologies and include multiple transceivers as needed to support these technologies.

[0115] Figure 3Another example of an ED 110 and base stations 170a, 170b, and / or 170c is shown. The ED 110 is used to connect people, objects, machines, etc. The ED 110 can be widely used in various scenarios, such as cellular communication, device-to-device (D2D), vehicle to everything (V2X), peer-to-peer (P2P), machine-to-machine (M2M), machine-type communication (MTC), internet of things (IOT), virtual reality (VR), augmented reality (AR), industrial control, autonomous driving, telemedicine, smart grid, smart home, smart office, smart wearable, smart transportation, smart city, drone, robot, remote sensing, passive sensing, positioning, navigation and tracking, automatic distribution, mobility, etc.

[0116] Each ED 110 represents any suitable end user device for wireless operation, and can include (or can be referred to as) a UE, WTRU, mobile station, fixed or mobile subscriber unit, cellular phone, STA, MTC device, PDA, smartphone, laptop, computer, tablet, wireless sensor, consumer electronics device, smartbook, vehicle, car, truck, bus, train, or IoT device, industrial device, or means (e.g., a communication module, modem, or chip) of the above devices, among other possibilities. Future generations of ED 110 can be referred to using other terminology. The base stations 170a and 170b are T-TRPs, hereinafter referred to as T-TRPs 170. Also shown in Figure 3 NT-TRPs, hereinafter referred to as NT-TRPs 172. Each ED 110 connected to the T-TRPs 170 and / or NT-TRPs 172 can be dynamically or semi-statically turned on (i.e., established, activated, or enabled), turned off (i.e., released, deactivated, or disabled), and / or configured in response to one or more of connection availability and connection necessity.

[0117] The ED 110 includes a transmitter 201 and a receiver 203 coupled to one or more antennas 204. Only one antenna 204 is shown in the figure. One, some or all of the antennas can also be panels. The transmitter 201 and receiver 203 can be integrated as a transceiver, for example. The transceiver is used to modulate data or other content for transmission by at least one antenna 204 or a network interface controller (NIC). The transceiver is also used to demodulate data or other content received by the at least one antenna 204. Each transceiver includes any suitable structure for generating a signal for wireless or wired transmission and / or for processing a signal received via wireless or wired transmission. Each antenna 204 includes any suitable structure for transmitting and / or receiving wireless or wired signals.

[0118] The ED 110 includes at least one memory 208. The memory 208 stores instructions and data used, generated, or collected by the ED 110. For example, the memory 208 could store software

[0119] instructions or modules used to implement part or all of the functionality described herein, and executed by the one or more processing units 210. Each memory 208 includes any suitable type of volatile and / or non-volatile memory, such as RAM, ROM, hard disk, optical disk, subscriber identity module (SIM) card, memory stick, secure digital (SD) card, processor cache, etc. The ED 110 can also include one or more input / output devices (not shown) or interfaces (e.g., wired interfaces to the Internet 150). The input / output devices support interaction with a user or other devices, systems, or networks. Each input / output device includes any suitable structure for providing information to or from a user, such as a speaker, microphone, keypad, keyboard, display, or touch screen, including network interface communications. Figure 1

[0120] ​ED 110 also includes a processor 210 for performing various operations, including operations related to preparing for transmission of uplink transmissions to NT-TRPs 172 and / or T-TRPs 170, operations related to processing downlink transmissions received from NT-TRPs 172 and / or T-TRPs 170, and operations related to processing sidelink transmissions to and from another ED 110. Processing operations related to preparing for transmission of uplink transmissions can include operations such as encoding, modulation, transmit beamforming, and generating symbols for transmission. Processing operations related to processing downlink transmissions can include operations such as receive beamforming, demodulation, and decoding received symbols. According to this embodiment, downlink transmissions can be received by receiver 203, possibly using receive beamforming, and processor 210 can extract signaling (e.g., by detecting and / or decoding the signaling) from the downlink transmissions. For example, the signaling can be reference signals transmitted by NT-TRPs 172 and / or T-TRPs 170. In some embodiments, processor 276 implements transmit beamforming and / or receive beamforming according to an indication of a beam direction received from T-TRPs 170, e.g., beam angle information (BAI). In some embodiments, processor 210 can perform operations related to network access (e.g., initial access) and / or downlink synchronization, e.g., operations related to detecting synchronization sequences, decoding and acquiring system information, etc. In some embodiments, processor 210 can perform channel estimation, e.g., using reference signals received from NT-TRPs 172 and / or T-TRPs 170.

[0121] Although not shown, processor 210 can form part of transmitter 201 and / or receiver 203. Although not shown, memory 208 can be part of processor 210.

[0122] Processor 210, as well as processing components in transmitter 201 and receiver 203, can each be implemented by one or more processors designed to perform instructions stored in a memory (e.g., memory 208). Alternatively, some or all of processor 210, as well as processing components in transmitter 201 and receiver 203, can be implemented using special-purpose circuitry.

[0123] In some embodiments, T-TRP 170 can go by other names, such as a base station, a base transceiver station (BTS), a wireless base station, a network node, a network equipment, a network side device, a transmission / reception node, a NodeB, an evolved NodeB (eNodeB or eNB), a Home eNodeB, a next Generation NodeB (gNB), a transmission point (TP), a site controller, an access point (AP) or a wireless router, a relay station, a remote radio head, a ground node, a ground network equipment or a ground base station, a BBU, a RRU, a radio unit (RU), an AAU, a RRH, a CU, a DU, a positioning node, among other possibilities. T-TRP 170 can be a macro BS, a micro BS, a relay node, a donor node, etc., or a combination thereof. T-TRP 170 can refer to the above devices, or to an apparatus (e.g., a communication module, a modem, or a chip) in the above devices.

[0124] In some embodiments, CU (or CU control plane (CP) and CU user plane (UP)), DU, or RU can go by other names. For example, in an open RAN (ORAN) system, CU can also be referred to as an open CU (O-CU), DU can also be referred to as an open DU (O-DU), CU-CP can also be referred to as an open CU-CP (O-CU-CP), CU-UP can also be referred to as an open CU-UP (O-CU-CP), and RU can also be referred to as an open RU (O-RU). Any of CU (or CU-CP, CU-UP), DU, or RU can be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0125] In some embodiments, various parts of T-TRP 170 can be distributed. For example, some modules of T-TRP 170 can be located at a location remote from a device that houses the antennas of T-TRP 170, and can be coupled to the device that houses the antennas through a communication link (not shown), sometimes referred to as front-haul, e.g., common public radio interface (CPRI). Thus, in some embodiments, the term T-TRP 170 can also refer to modules that perform the processing operations of ED 110 position determination, resource allocation (scheduling), message generation and encoding / decoding, etc. on the network side, which are not necessarily part of the device that houses the antennas of T-TRP 170. These modules can also be coupled to other T-TRPs. In some embodiments, T-TRP 170 can actually be multiple T-TRPs that work together, e.g., through coordinated multipoint transmission, to serve ED 110.

[0126] The T-TRP 170 includes at least one transmitter 252 and at least one receiver 254 coupled to one or more antennas 256. Only one antenna 256 is shown in the figure. One, some or all of the antennas can also be panels. The transmitter 252 and receiver 254 can be integrated as a transceiver. The T-TRP 170 also includes a processor 260 for performing various operations, including operations related to preparing transmissions for downlink transmissions to the ED 110, processing uplink transmissions received from the ED 110, preparing transmissions for backhaul transmissions to the NT-TRP 172, and processing transmissions received from the NT-TRP 172 over backhaul. The processing operations related to preparing transmissions for downlink or backhaul transmissions can include operations such as encoding, modulation, precoding (e.g., MIMO precoding), transmit beamforming, and generating symbols for transmission. The processing operations related to processing transmissions received in uplink or over backhaul can include operations such as receive beamforming, demodulation, and decoding received symbols. The processor 260 can also perform operations related to network access (e.g., initial access) and / or downlink synchronization, such as generating contents of a synchronization signal block (SSB), generating system information, etc. In some embodiments, the processor 260 also generates an indication of a beam direction, e.g., a BAI, which can be scheduled for transmission by the scheduler 253. The processor 260 performs other network-side processing operations described herein, e.g., determining a location of the ED 110, determining a location to deploy the NT-TRP 172, etc. In some embodiments, the processor 260 can generate signaling, e.g., to configure one or more parameters of the ED 110 and / or one or more parameters of the NT-TRP 172. Any signaling generated by the processor 260 is transmitted by the transmitter 252. Note that “signaling” used here can also be referred to as control signaling. Dynamic signaling can be transmitted in a control channel, e.g., a physical downlink control channel (PDCCH), and static or semi-static higher layer signaling can be included in packets transmitted in a data channel, e.g., a physical downlink shared channel (PDSCH).

[0127] The scheduler 253 can be coupled to the processor 260. The scheduler 253 can be included within or operate separately from the T-TRP 170, which can schedule uplink, downlink, and / or backhaul transmissions, including issuing scheduling grants and / or configuring grant-free (“configured grant”) resources. The T-TRP 170 also includes memory 258 that stores information and data. The memory 258 stores instructions and data used, generated, or collected by the T-TRP 170. For example, the memory 258 can store software

[0128] Although not shown, the processor 260 can form part of the transmitter 252 and / or the receiver 254. Further, the processor 260 can implement the scheduler 253, although not shown. Although not shown, the memory 258 can be part of the processor 260.

[0129] The processor 260, the scheduler 253, and the processing components in the transmitter 252 and the receiver 254 can each be implemented by the same or different one or more processors that execute instructions stored in memory, for example, the instructions in the memory 258. Alternatively, some or all of the processor 260, the scheduler 253, and the processing components in the transmitter 252 and the receiver 254 can be implemented using specialized circuitry, for example, a FPGA, GPU, or ASIC.

[0130] Although NT-TRP 172 is shown as a drone merely as an example, NT-TRP 172 can be implemented through any suitable non-ground based form. Moreover, in some embodiments, NT-TRP 172 can go by other names, such as a non-ground node, non-ground network device, or non-ground base station. NT-TRP 172 includes a transmitter 272 and a receiver 274 coupled to one or more antennas 280. Only one antenna 280 is shown in the figure. One, some or all of the antennas can also be panels. Transmitter 272 and receiver 274 can be integrated as a transceiver. NT-TRP 172 also includes a processor 276 for performing various operations, including operations related to preparing transmissions for downlink transmissions to ED 110, processing uplink transmissions received from ED 110, preparing transmissions for backhaul transmissions to T-TRP 170, and processing transmissions received from T-TRP 170 over backhaul. Processing operations related to preparing transmissions for downlink or backhaul transmissions can include operations such as encoding, modulation, precoding (e.g., MIMO precoding), transmit beamforming, and generating symbols for transmission. Processing operations related to processing transmissions received in uplink or over backhaul can include operations such as receive beamforming, demodulation, and decoding received symbols. In some embodiments, processor 276 implements transmit beamforming and / or receive beamforming according to beam direction information (e.g., BAI) received from T-TRP 170. In some embodiments, processor 276 can generate signaling, e.g., to configure one or more parameters of ED 110. In some embodiments, NT-TRP 172 implements physical layer processing, but not higher layer functions such as functions of medium access control (MAC) or radio link control (RLC) layers. Since this is merely one example, NT-TRP 172 can generally implement higher layer functions in addition to physical layer processing.

[0131] NT-TRP 172 also includes a memory 278 that stores information and data. Although not shown, processor 276 can form part of transmitter 272 and / or receiver 274. Although not shown, memory 278 can be part of processor 276.

[0132] The processor 276, and processing components of the transmitter 272 and receiver 274, respectively, can be implemented by the same or different one or more processors that are used to execute instructions stored in a memory, such as the instructions in the memory 278. Alternatively, some or all of the processing components of the processor 276, and transmitter 272 and receiver 274 can be implemented using specialized circuitry, for example, a programmed FPGA, GPU, or ASIC. In some embodiments, the NT-TRP 172 can actually be multiple NT-TRPs that work together, for example, through coordinated multipoint transmission, to serve the ED 110.

[0133] The T-TRP 170, NT-TRP 172, and / or ED 110 can include other components, which for brevity, have been omitted.

[0134] MIMO technology allows for antenna arrays composed of multiple antennas to perform signal transmission and reception to meet high transmission rate requirements. The above-mentioned ED 110 and T-TRP 170 and / or NT-TRP use MIMO to communicate over a wireless resource block. MIMO utilizes multiple antennas at a transmitting device and / or a receiving device to transmit parallel wireless signals over a wireless resource block. MIMO can beamform the parallel wireless signals to enable reliable multipath transmission of a wireless resource block. MIMO can bundle parallel wireless signals that transmit different data to increase data rate of a wireless resource block.

[0135] In recent years, MIMO (massive MIMO) wireless communication systems in which the above T-TRPs 170 and / or NT-TRPs 172 are configured with a large number of antennas have attracted extensive attention from academia and industry. In a massive MIMO system, the T-TRPs 170 and / or NT-TRPs 172 are usually configured with more than ten antenna elements (e.g., 128 or 256), while serving tens (e.g., 40) of EDs 110. The large number of antenna elements of the T-TRPs 170 and / or NT-TRPs 172 can greatly improve the spatial degrees of freedom of wireless communication, greatly improve the transmission rate, spectral efficiency and power efficiency, and largely eliminate the interference between cells. The increase in the number of antennas makes the size of each antenna element smaller and the cost lower. With the spatial degrees of freedom provided by the large number of antenna elements, the T-TRPs 170 and / or NT-TRPs 172 of each cell can simultaneously communicate with multiple EDs 110 in the cell on the same time-frequency resources, thereby greatly improving the spectral efficiency. The large number of antenna elements of the T-TRPs 170 and / or NT-TRPs 172 also makes each user have better spatial directivity for uplink and downlink transmission. Therefore, the transmission power of the T-TRPs 170 and / or NT-TRPs 172 and the EDs 110 is reduced, and the power efficiency is improved. When the number of antennas of the T-TRPs 170 and / or NT-TRPs 172 is large enough, the random channels between each ED 110 and the T-TRPs 170 and / or NT-TRPs 172 can approach an orthogonal state. The interference between cells and users and the influence of noise can be eliminated. The above-mentioned various advantages make the massive MIMO system have good application prospects.

[0136] A MIMO system can include a receiving device connected to receive (Rx) antennas, a transmitting device connected to transmit (Tx) antennas, and a signal processor connected to the transmitting device and the receiving device. Each of the Rx antennas and the Tx antennas can include a plurality of antennas. For example, the Rx antennas can have a uniform linear array (ULA) antenna array in which a plurality of antennas are arranged in a row with even intervals. When a radio frequency (RF) signal is transmitted through the Tx antennas, the Rx antennas can receive a signal that is reflected and returned from a forward target.

[0137] In this application, the central device can be one of the network nodes 170a or 170b in Figure 1 the user equipment can be one of the EDs 110a to 110j in Figure 1 In this application, the central device can be one of the network nodes 170a or 170b in Figure 2 the user equipment can be one of the EDs 110a to 110j in Figure 2one of the EDs 110a-110d in FIG. 1; or, the central device can be Figure 3 one of the T-TRPs 170 or the NT-TRPs 172 in FIG. 1, and the user device can be Figure 3 the ED 110 in FIG. 1.

[0138] Figure 4 is an example of a channel model for a MIMO system. The transmitting device is connected to four Tx antennas, i.e., x1-x4, and the receiving device is connected to four Rx antennas, i.e., y1-y4. An RF signal transmitted through x1 can be received by y2 through channel h21. An RF signal transmitted through x3 can be received by y1 through channel h13.

[0139] In a MIMO system, to implement system synchronization, channel information feedback, and data transmission, etc., channel estimation needs to be performed on the uplink channel or the downlink channel. Channel estimation refers to a process of reconstructing or recovering a received signal to compensate for signal distortion caused by channel fading and noise. In channel estimation, a reference signal transmitted by the transmitting device can be used to track changes in the time domain and / or the frequency domain of the channel, so as to reconstruct or recover the received signal. The reference signal can also be referred to as a pilot signal or a reference sequence, etc. For ease of understanding, it is described as a reference signal in the following description. For example, the reference signal includes a channel state information-reference signal (CSI-RS), a sounding reference signal (SRS), a demodulation reference signal (DMRS), a phase tracking reference signal (PT-RS), or a cell reference signal (CRS). The above listed reference signals are only examples and should not constitute any limitation on the present application. The present application does not exclude the possibility of defining other reference signals in future protocols to achieve the same or similar functions.

[0140] To facilitate understanding of the embodiments of the present application, the CSI-RS is described in detail below by way of example. The CSI-RS is mainly used for downlink channel estimation corresponding to a physical antenna port. For example, a receiving device (i.e., a user equipment) can perform channel estimation for each physical antenna port according to a CSI-RS transmitted by a transmitting device (i.e., a central device), so as to feed back channel state information (CSI) according to a channel estimation result. The CSI can include channel quality indicator (CQI), precoding matrix indicator (PMI), layer indicator (LI), and rank indicator (RI), and other related information. The CSI is used for reconstructing or precoding a downlink channel. In some embodiments, a process of the central device obtaining the CSI can include: the central device transmitting a reference signal to the UE; the UE obtaining a CSI estimation value according to the received reference signal; the UE selecting a precoding vector from a codebook according to the CSI estimation value; the UE feeding back an index of the precoding vector to the central device; and the central device determining a CSI reconstruction value with reference to the index of the precoding vector. The CSI reconstruction value can be a CSI value closest to a true value of the CSI that the central device can obtain.

[0141] In an embodiment, the transmitting device maps a reference signal sequence to certain physical resources, and transmits the reference signal on the certain physical resources. The sequence of the reference signal and the physical resources are known to both the transmitting device and a receiving device receiving the reference signal. Therefore, the receiving device can perform channel estimation according to the known reference signal sequence and the received signal.

[0142] The transmitting device can map a sequence to physical resources to transmit the reference signal. The physical resources can include a plurality of resource elements, which are physical resources allocated to the reference signal transmission. For example, when transmitting a DM-RS, the resource elements have common resource blocks allocated to physical downlink shared channel (PDSCH) transmission.

[0143] The location of the physical resources of the reference signal can be referred to as a reference signal pattern or a pilot pattern. The location of the physical resources is usually described by at least one of the following dimensions: a time dimension, a frequency dimension, and a spatial dimension.

[0144] The time dimension can be represented by one or more time domain resource units. A time domain resource unit can include, but is not limited to, a symbol, an orthogonal frequency division multiplexing (OFDM) symbol, and a time slot. In some embodiments, a time domain unit can be represented by a symbol index, an OFDM symbol index, or a time slot index.

[0145] The frequency dimension can be represented by one or more frequency domain resource units. A frequency domain resource unit can include, but is not limited to, a subcarrier or a subband. In some embodiments, a frequency domain unit can be represented by a subcarrier index or a subband index. In some embodiments, a frequency domain unit can also be represented by a resource element (RE) index, a resource block (RB) index, or a resource block group (RBG) index. An RE includes a symbol in the time domain and a subcarrier in the frequency domain, and an RE index can be used to indicate the location of a subcarrier. An RB includes a time slot in the time domain and 12 consecutive subcarriers in the frequency domain. An RB index can be used to indicate the location of 12 subcarriers. An RBG consists of a group of RBs, and an RBG index can be used to indicate the location of a group of subcarriers.

[0146] The spatial dimension can be represented by one or more spatial domain resource units. A spatial domain resource unit can be represented by an antenna port. In embodiments of the present application, an antenna port can be a Tx antenna. An antenna port can be identified by an antenna port index.

[0147] For the purpose of understanding the embodiments of the present application, in the following exemplary description, a symbol index is used to represent the location of a time domain resource unit, a subcarrier index is used to represent the location of a frequency domain resource unit, and an antenna port index is used to represent the location of a spatial domain resource unit.

[0148] The above-described channel estimation process is only exemplary and should not constitute any limitation on the present application. Channel estimation processes are known in the conventional art, and detailed descriptions of specific processes are omitted herein for the sake of brevity.

[0149] The receiving device can be an ED (i.e., a user equipment), and the transmitting device can be a T-TRP or an NT-TRP (i.e., a central device); or the receiving device can be a T-TRP or an NT-TRP (i.e., a central device), and the transmitting device can be an ED (i.e., a user equipment). In some embodiments, when the reference signal in these embodiments is a downlink signal (e.g., a CSI-RS), the transmitting device can be a central device, and the receiving device can be a user equipment. When the reference signal in these embodiments is an uplink signal (e.g., an SRS), the transmitting device can be a user equipment, and the receiving device can be a central device. Although one transmitting device can transmit a reference signal to one or more receiving devices, for simplicity, the following embodiments focus on the method between one transmitting device and one receiving device; these examples are not intended to limit the scope of the present application.

[0150] As mentioned above, the problem to be solved is how to determine the information related to the DL channel of the UE without transmitting the DL channel measurement. In some detailed designs, the central device can be associated with one or more sets of environmental parameters, and each set of environmental parameters can be associated with one DL channel measurement result. In embodiments of the present application, the central device transmits second information related to a first set of environmental parameters to the user equipment, so as to determine a reference channel of the user equipment, which can approximately represent the DL channel of the user equipment under the channel condition represented by the first set of environmental parameters. Therefore, the central device can determine the information of the DL channel without transmitting the channel measurement of the DL channel related to a specific set of environmental parameters, which can reduce the signaling overhead of transmitting the channel measurement. The communication method provided by the present application is described below in combination with Figure 5 The communication method provided by the present application is described below in combination with

[0151] Figure 5 A flowchart of a communication method 500 is shown. The method can be applied to single-user multiple-input-multiple-output (SU-MIMO). The method can also be applied to MU-MIMO. Figure 5 The method 500 shown includes steps S510 and S520. Each step is described in detail below.

[0152] In S510, the central device transmits first information indicating a first set of reference channels related to a first set of environmental parameters to the user equipment.

[0153] The "first set of reference channels" is named only for differentiation, and does not limit the protection scope of embodiments of the present application. Similarly, the "first set of environmental parameters" and the "first threshold" and the like in the following description are also named only for differentiation, and do not limit the protection scope of embodiments of the present application, which will not be described again hereinafter.

[0154] In some possible implementations, the center device determines the first set of reference channels according to the first set of environment parameters. In a detailed design, the first set of reference channels can be selected from a plurality of channel data samples (e.g., channel data samples) measured and accumulated by the user device and / or the center device related to the first set of environment parameters. The first set of reference channels includes reference channels, where and is a positive integer, . The reference channels in the first set of reference channels are dynamic and adaptive, constantly updated over time. For example, some reference channels are eliminated from the first set of reference channels, and some reference channels are added to the first set of reference channels. The size of the first set of reference channels, i.e., , can be fixed or change over time.

[0155] For example, reference channels can be determined by any of the following operations: randomly selecting channel data samples from channel data samples as reference channels; selecting the most representative channel data samples from channel data samples by K-means, Gaussian Mixture Model (GMM), or other classification algorithms; or, selecting the most representative channel data samples from channel data samples according to the distance between the channel data samples.

[0156] For example, the center device scores the distance between channel data samples according to a scoring (or measuring) function based on the public information of the first set of environment parameters, and then the center device turns channel data samples into a graph according to the distance between the channel data samples. Then, the center device can select the channel data samples with the highest degree. Degree is a graph theory term that indicates how many connections a node on a graph has. Nodes with higher degrees are called hub nodes on the graph. The higher the degree of a node, the more typical or representative the node is of the reference channel.

[0157] The scoring (or measuring) function can include but is not limited to: Euclidean function; inner product between two vectors; heat kernel function when the channel can be represented by a vector.

[0158] The "most representative ​The “one channel data sample” can refer to that the channel data sample can be used as a reference channel for pairing at least two user equipments. The “most representative The “one channel data sample” can also refer to that the projected channel of the channel data sample can be used for pairing at least two user equipments.

[0159] In some possible implementations, the first set of reference channels can be generated by a digital environment simulator or a digital environment model. For example, the digital environment simulator (or model) is a digital twin related to the first set of environment parameters.

[0160] In some possible implementations, the first set of reference channels includes a plurality of compressed reference channels, the plurality of compressed reference channels being determined according to a compression function compressing a plurality of reference channels, the plurality of reference channels being determined according to the plurality of channel data samples. The plurality of reference channels includes part or all of the one reference channel. The compression function is determined according to the first set of environment parameters.

[0161] In some implementations, the compression function is related to common information according to the first set of environment parameters. For example, the compression function is related to common information determined according to the plurality of channel data samples according to the first set of environment parameters. In other words, the plurality of compressed reference channels is determined by the common information.

[0162] In some possible implementations, the compression function is determined according to a pilot pattern down-sampling a pre-compression function, the pre-compression function being determined according to the set of environment parameters.

[0163] The pilot pattern includes any one of the following: a uniform pilot pattern, a dense pilot pattern, or a non-uniform sparse pilot pattern. The pilot pattern can also be referred to as any one of a pilot location pattern, a reference signal arrangement pattern, or a reference signal location pattern.

[0164] In some possible implementations, the pilot pattern can be pre-negotiated between the center device and the user equipment.

[0165] In S520, the center device sends second information related to the first set of environment parameters to the user equipment, the second information being used to determine one or more reference channels from the first set of reference channels.

[0166] In some implementations, the user equipment determines one or more reference channels from the first set of reference channels, each reference channel having a distance to a DL channel of the user equipment less than or equal to a first threshold.

[0167] ​The DL channel is a wireless channel for receiving information from the central device. The distance between the DL channel and the reference channel represents the similarity or correlation between the DL channel and the reference channel. The first threshold is a distance threshold for selecting one or more reference channels that have sufficient similarity with the DL channel. When a reference channel has sufficient similarity with the DL channel, the reference channel can be used to represent the DL channel. For example, some parameters of the reference channel can be used to represent the corresponding parameters of the DL channel, so that it can be determined according to two reference channels whether two user devices corresponding to two DL channels can be paired.

[0168] In the detailed design, the one or more reference channels include one or more of the following: a reference channel closest to the DL channel, a reference channel second closest to the DL channel, a reference channel third closest to the DL channel, and the like. In some scenarios, the closest reference channel, the second closest reference channel, and the like can help the central device determine the change of channel conditions related to the user device or the change of position of the user device. For example, the central device receives information indicating that the closest reference channel is reference channel #1 and the second closest reference channel is reference channel #2 in a first transmission period; the central device receives information indicating that the closest reference channel is reference channel #2 and the second closest reference channel is reference channel #3 in a second transmission period. Then, the central device can determine which changes of position or channel conditions of the user device have occurred according to the changes of the closest reference channel and the second closest reference channel.

[0169] When the first group of reference channels includes multiple reference channels, one of the one or more reference channels can be one of the multiple reference channels. When the first group of reference channels includes multiple compressed reference channels, one of the one or more reference channels can be one of the compressed reference channels.

[0170] For example, the user device can determine the one or more reference channels through a scoring function. The scoring function can be the same as mentioned in S510.

[0171] In some implementations, the second information indicates one or more of the following: a first pilot pattern, a first compression function, a first scoring function, and a first threshold. The first compression function is used to determine one or more of the following: channel measurements of the one or more reference channels in the first group of reference channels and the DL channel of the user device. The first scoring function is used to determine the distance between the DL channel and one of the first group of reference channels. The first threshold is used to determine the one or more reference channels in the first group of reference channels.

[0172] The first pilot pattern can be the same as the pilot pattern mentioned in S510. The first compression function can be the same as the compression function mentioned in S510. The first scoring function can be the same as the scoring function mentioned in S510. In a detailed design, the first scoring function and / or the first threshold can be pre-negotiated by the central device and the user equipment, so that the central device can not need to notify the user equipment of the first scoring function and / or the first threshold. The first compression function can be stored by the user equipment, so that the central device can not need to notify the user equipment of the first compression function. The first pilot pattern can be pre-negotiated by the central device and the user equipment, so that the central device can not need to notify the user equipment of the first pilot pattern.

[0173] In the present application, the central device can be related to one or more sets of environmental parameters. The central device can notify the user equipment of which set of environmental parameters is related to by sending second information related to the first set of environmental parameters, and help the user equipment to determine at least one reference channel from a set of reference channels related to the set of environmental parameters indicated by the second information. The above technical solution can ensure the effectiveness of the reference channel from the user equipment affected by the set of environmental parameters. In other words, the above technical solution can avoid the central device operating (for example, user equipment pairing) based on outdated reference channels. In addition, the distance between the at least one reference channel and the DL channel of the user equipment can be less than or equal to a threshold value. Therefore, the central device does not need to send channel measurement of the DL channel to determine information related to the DL channel, solving the problem of large signaling overhead caused by sending channel measurement.

[0174] Figure 6 A schematic flowchart of a communication method 600 in user equipment pairing of an embodiment of the present application is shown. Figure 6 The method 600 shown shows how the central device obtains a reference channel in the first set of reference channels mentioned in S510 of the method 500. The method 600 can be executed before S510. The method includes steps S601 and S602.

[0175] In S601, the central device vectorizes a plurality of channel data samples related to the first set of environmental parameters. In S602, the central device determines the reference channel from the at least one reference channel in the first set of reference channels mentioned in S510 of the method 500.

[0176] Figure 7 An example of vectorizing a three-dimensional tensor into a vector is shown. In the example, a channel data sample is represented as a three-dimensional tensor represented by Figure 7 wherein × × × × ​​​the size of the matrix. In particular, × × denotes a three-dimensional tensor includes a matrix (or two-dimensional tensor) with rows and columns. denotes the number of REs, denotes the number of transmit (Tx) antenna ports, denotes the number of receive (Rx) antenna ports. In the order of vectorization of RE, Tx, and Rx, is vectorized into a column vector denoted by × , where . The disclosure below uses “RE→Tx→Rx” to denote the above order of vectorization. × denotes a vector with rows and 1 column, which is the product of .

[0177] When the first channel data sample is represented as a tensor denoted by × × , the device can vectorize it into , i.e., the first column vector, in the order of RE→Tx→Rx. When the second channel data sample is represented as a tensor denoted by × × , the device can vectorize it into denoted by × , where , i.e., the second column vector, in the same order. The device can vectorize each channel data sample denoted by × × into a vector denoted by × in the order of RE→Tx→Rx until the device vectorizes all channel data samples in the tensor into column vectors. Then, the central device can juxtapose all the column- vectorized channel data samples into a matrix. Juxtaposition or juxtaposition processing is a process of arranging column vectors by columns, or arranging row vectors by rows, to obtain a matrix.

[0178] In one example, a sufficient number (e.g., 2 vectorized channel data samples are put into Figure 8of × In the matrix: ,in , × Representation matrix have Action and List, It is the rank of the set of environmental parameters, which is related to the complexity of the public information. In mathematics, It is the number of principal components of public information.

[0179] It should also be noted that in the derivation above, we will... Set it as a column vector. Without sacrificing generality, if... Setting it as a row vector allows for a sufficient number (e.g., The vectorized channel data samples are arranged into × In the matrix: ,in × Representation matrix have lines and Columns. Row vectors and column vectors are mathematically equivalent. In the following discussion, we will use the column vector version.

[0180] In some implementations, S601 can also be executed by a remote data center or a powerful user device.

[0181] In some implementations, channel data samples can be accumulated and prepared in the following ways, including but not limited to: 1) Channel data samples can be measured and accumulated by the central equipment, user equipment, or both during historical communication. For example, the central equipment can use uplink sounding reference signal (UL-SRS) to probe the channel and accumulate channel data samples. The user equipment can estimate the DL channel and then provide feedback on the CSI-RS to the central equipment. The central equipment accumulates the CSI-RS feedback as channel data samples.

[0182] 2) Channel data samples can be provided through feedback from physical reference user equipment (PRA). These PRAs (also known as anchor user equipment or sensing user equipment) can be deployed at key locations in the target wireless environment. Alternatively, they can be deployed at random locations within the target wireless environment. The PRAs can receive DL signals from a central device and estimate the DL channel. After estimating the DL channel, the PRAs can provide feedback about their DL channel to the central device, which accumulates this feedback as channel data samples. For example, the PRAs can provide feedback about their DL channel in a compressed format.

[0183] 3) Channel data samples can be virtually generated by a digital environment simulator. The digital environment simulator can be referred to as a digital twin of the target wireless environment.

[0184] In practice, channel data samples can be accumulated by dynamically combining the aforementioned alternative methods. For example, in the first phase where there are no channel data samples at all, the first public information is based on channel data samples accumulated and prepared using the third method. Then, the first public information of the first phase can be accumulated and prepared using the first and / or second methods to acquire channel data samples during the second phase. The second public information can be refined using the channel data samples accumulated during the second phase. Furthermore, the physical reference user equipment of the second method may detect some significant changes in the target wireless environment. Significant changes in the target wireless environment may trigger a third round of third public information refinement. The central equipment can decide which phase the system enters or remains in.

[0185] In some implementations, channel data samples can preferably be accumulated, stored, and processed on a central device, as the central device may have more powerful computing capabilities and larger storage space than user equipment. However, channel data samples can be accumulated, stored, and processed in a remote data center connected to the central device via the core network or the Internet; alternatively, channel data samples can be optionally accumulated, stored, and processed on user equipment, especially equipment with powerful computing capabilities and large storage space.

[0186] In S602, the central equipment originates from... Select from channel data samples One channel data sample as One reference channel.

[0187] For example, the central equipment can be obtained from Channel data samples Choose a group ( ) channel data samples, to obtain : wherein the original index of the selected data sample in is returned. The first set of reference channels can be regarded as an example. The method of selecting reference channels is described in detail in S510. Herein, no further description is given.

[0188] In some scenarios, for example, terabit multiple-input-multiple-output (T-MIMO) scenarios, the dimension of the reference channels (for example, ) can be very large, and the center device can need to compress the reference channels, for example, the reference channel set , before sending.

[0189] As described in S510, the center device can compress part or all of the selected reference channels and send the compressed reference channels to the user device. In some implementations, the center device can compress the reference channels according to the common information.

[0190] Figure 9 A schematic flow chart illustrating a method 700 of how the center device determines the common information and compresses the reference channels according to the first environment to obtain the compressed reference channels is shown, as described in S510 of method 500. The method 700 can be performed before S510. The method 700 includes steps S701 and S702.

[0191] In S701, the center device obtains the common information of the first set of environment parameters.

[0192] For example, the common information is generated by the center device according to channel data samples. For another example, the common information is generated by a powerful user device, a remote data center, or other center devices and then sent to the center device. The method of accumulating channel data samples is described in detail in S601. Herein, no further description is given.

[0193] In practice, the channel data samples can be accumulated by combining the above-mentioned alternative methods mentioned in S601 in a dynamic manner. Different ways of accumulating channel data samples will result in different channel data samples, and different channel data samples will produce different common information. For example, in the first phase without any channel data samples, the first set of channel data samples can be accumulated and prepared by the third method mentioned in S601, and the common information can be determined according to the first set of First public information is determined from one channel data sample. Then, a second set can be accumulated and prepared during the second phase using the first and / or second method. One channel data sample. The second public information can be based on the second set. The channel data samples are determined, or the first common information can be obtained through the second group. Each channel data sample is refined into second common information. Furthermore, the physical reference user equipment (PRA) of the second method may detect significant changes related to the target environmental parameter set. These significant changes may trigger a third round of refining the second common information into third common information. The central equipment can then determine which phase the system enters or remains in.

[0194] Public information can be represented in various forms, including but not limited to: one or more statistical functions with parameters; one or more matrices; one or more trained artificial intelligence (AI) models, such as deep neural networks (DNNs).

[0195] For example, Each channel data sample can be as mentioned in method 600. or The following publicly available information will As An example of a channel data sample is given.

[0196] In some implementations, public information is matrix-based. For example, public information can be represented by a matrix, and then the following operations can be performed to calculate the public information.

[0197] The aforementioned equipment, such as central equipment, powerful user equipment, remote data centers, and other central equipment, can decompose the matrix. ,like Figure 8 As shown. If... If each channel data sample is vectorized into a column vector, then they can be concatenated column by column; if... If each channel data sample is vectorized into a row vector, then it can be concatenated row by row. These two concatenations are mathematically equivalent. In the following discussion, we will take column-wise vectorization and column-wise concatenation as examples. Decomposition can be used to compute the basis of the matrix. This basis can be called the channel space basis, representing the vectors derived from the data from the channel vectors. The decomposition is based on common information obtained from channel data samples. It can be based on singular vector decomposition (SVD) to generate a channel space basis that is an orthogonal or unitary matrix. Alternatively, different methods can be used to perform the decomposition, resulting in a non-orthogonal channel space basis.

[0198] Decomposition is a type of reduced-rank SVD: ,in yes × Unitary matrix (or orthogonal matrix). If If set as a column vector, then It is the channel space basis, representing all Public information shared by each channel data sample. If If set as a row vector, then It is the channel space basis, representing the common information of the channel. In the following discussion, we will use the column vector version.

[0199] Calculate the channel space basis from multiple channel data samples The device can be used through the inverse of the channel space basis. Each vectorized channel data sample Projecting to an equivalent low-dimensional space representation This low-dimensional spatial representation can be called the low-dimensional spectral coefficient representation: ,in yes ×1 vector. If the channel space basis... If it is an orthogonal matrix or a unitary matrix, then the inverse of the channel space basis is... It is the Hermite transpose of the channel space basis ( ): .because Include With all the key information, the device can project the spectral coefficient representation back into the original channel data space: ,like Figure 10 As shown in the diagram. The device may tend to use a channel space basis. Low-dimensional space representation Channel data samples are stored in a format that is not a vectorized set of multiple channel data samples. Stored in the form of .

[0200] In some other implementations, public information is AI-based; for example, public information can be represented using AI models. Public information can be calculated through the following operations.

[0201] like Figure 11 As shown, the device can use a non-linear coding function. ( (For adjustable parameters), its approximation and using a non-linear decoding function ( (For adjustable parameters), its approximation Nonlinear encoding functions and nonlinear decoding functions can be cascaded into... And can be by and This is implemented as a DNN with tunable neurons. In DNN-like implementations, the device can take input... Choose a latent layer from the equivalent low-dimensional space ( The output of ).

[0202] The device can train the DNN using stochastic gradient descent (SGD) on the learning objective, so that all One channel data sample ( , ... MSE Minimize, thereby adjusting parameters and .

[0203] S702: The central equipment compresses the reference channel based on public information.

[0204] Public information can be seen as an example of information indicating the compression function mentioned in method 500.

[0205] For example, compression functions can be constructed based on public information. A compression function can be represented as... . This indicates that common information is used to process or compress the reference channel. The result is a compressed reference channel.

[0206] The central device compresses the reference channel according to a compression function. Furthermore, in this example, the compression function is constructed based on public information.

[0207] For example, if public information is represented by a matrix model, then the central device can... Reference channel set Projected onto a low-dimensional spectral coefficient vector. The central device can store the reference channel set in the low-dimensional spectral space as... ,in yes A ×1 vector, instead of in the original space In the middle. If public information is represented by an AI model, the central device can use the AI ​​model to access the reference channel set. Projection to low-dimensional space As shown in Figure 12 . It can be seen as an example of , where is the common information, is the reference channel, Other forms of common information can be used instead.

[0208] In order for the user equipment to determine the one or more reference channels mentioned in S520 of the method 500, the user equipment needs to obtain the pilot pattern and / or the common information related to the first set of environmental parameters.

[0209] Figure 13 A schematic flowchart illustrating a method 800 of how the user equipment obtains the pilot pattern and the common information related to the first set of environmental parameters is shown. The method 800 can be performed in synchronization with S520. The method 800 comprises steps S801 to S803.

[0210] In S801, the center device obtains the common information related to the first set of environmental parameters.

[0211] The method of obtaining the common information is described in detail with reference to S701. Here, it will not be repeated.

[0212] For example, the center device can have the channel space bases mentioned in the method 700 to represent the common information of the first set of environmental parameters. The center device can apply the channel space bases to the wireless channel between the center device and the user equipment that can be related to the first set of environmental parameters, or the center device can inform the user equipment of the channel space bases so that the user equipment can apply the channel space bases to the wireless channel between the center device and the user equipment.

[0213] Any device with channel space bases can project the channel estimate to a low-dimensional spectral coefficient vector ( ×1 ), to obtain the channel estimate result ( × , ) of the wireless channel, where , If the channel space bases are orthonormal or unitary, then , . Therefore, the center device can configure or inform the user equipment of the channel space bases , and vice versa.

[0214] In S802, the center device sends information indicating the common information to the user device.

[0215] The user device can also receive the common information related to the first set of environment parameters from other devices, such as a remote data center, a powerful user device, or other center devices. The common information can be generated by the user device in the case of sufficient power.

[0216] In S803, the center device sends information indicating the pilot pattern to the user device.

[0217] In some implementations, the pilot pattern can be generated by Figure 14 . . The matrix is represented, each row of the matrix has only one "1" indicating the position to be used as a pilot, where . The matrix has rows and columns. The center device can send pilots on these positions indicated by the matrix . The user device can estimate the channel coefficients on these positions indicated by the matrix to obtain the channel estimation result (represented by . ). The matrix may also have other forms explicitly or implicitly.

[0218] The center device and the user device can use a non-uniform sparse pilot pattern, i.e. , which can reduce the pilot overhead.

[0219] For example, the near-optimal non-uniform pilot pattern can be calculated by the column rotation "QR" decomposition (QRD) on the channel space basis . . Several "strongest" column rotation pivots (in a typical column rotation QRD, the column rotation pivots are sorted by their importance or contribution) in will indicate the most important or most contributive positions to arrange reference signals (or pilots) for reconstruction purposes.

[0220] In order to obtain the channel estimation result for the user device to determine one or more reference channels from the first set of reference channels, both the center device and the user device can configure the same pilot pattern. In the implementation where the center device can send the matrix to the user device, there can be other alternatives, such as the following.

[0221] In some implementations, both the center device and the user device can follow a traditional uniform pilot pattern defined in a wireless standard. For example, in 5G-NR specification, there is 1 pilot per RB, and the pilots are arranged regularly in the RB direction. Both the center device and the user device can align the parameters regarding the uniform pilot pattern using minimum control overhead. Both the center device and the user device can be configured to have or inform each other to have channel spatial bases The center device can transmit pilots at the locations indicated by the matrix The user device can receive pilots at the locations indicated by the matrix The user device can estimate the wireless channel according to the received pilots and obtain channel estimation results Then, the user device projects the channel estimation results onto a low-dimensional spectral coefficient vector The user device can send the low-dimensional spectral coefficient vector to the center device, and the center device can receive the low-dimensional spectral coefficient vector and project it back to the original channel space (H) with channel spatial bases . .

[0222] In other implementations, both the center device and the user device can follow a random function that generates a random pilot pattern according to a given random seed, where the random function can be defined in a wireless standard. Both the center device and the user device can align the parameters regarding the random function, the random seed, and other parameters using minimum control overhead. Both the center device and the user device can be configured to have or inform each other to have channel spatial bases The center device can transmit pilots at the locations indicated by the matrix The user device can receive pilots at the locations indicated by the matrix The user device can estimate the wireless channel according to the received pilots and obtain channel estimation results Then, the user device projects the channel estimation results onto a low-dimensional spectral coefficient vector The user device can send the low-dimensional spectral coefficient vector to the center device, and the center device can receive the low-dimensional spectral coefficient vector and project it back to the original channel space (H) with channel spatial bases . .

[0223] In other implementations, both the center device and the user device can follow a generating function that generates a pilot pattern according to channel spatial bases A pilot pattern is generated, where a generating function can be defined in a wireless standard. Both the central device and the user device can align parameters regarding the generating function and other parameters with minimum control overhead. Both the central device and the user device can be configured to have or inform each other to have channel spatial bases The central device can transmit pilots at locations indicated by the matrix The user device can receive pilots at locations indicated by the matrix The user device can estimate a wireless channel from the received pilots and obtain channel estimation results The user device then projects the channel estimation results onto a low-dimensional spectral coefficient vector The user device can transmit the low-dimensional spectral coefficient vector to the central device. The central device can receive the low-dimensional spectral coefficient vector and project it back to the original channel space with channel spatial bases .

[0224] In some other implementations, both the central device and the user device can follow a generative AI model that generates a pilot pattern. Both the central device and the user device can align parameters regarding the generative AI model and other parameters with minimum control overhead. Both the central device and the user device can be configured to have or inform each other to have channel spatial bases The central device can transmit pilots at locations indicated by the matrix The user device can receive pilots at locations indicated by the matrix The user device can estimate a wireless channel from the received pilots and obtain channel estimation results The user device then projects the channel estimation results onto a low-dimensional spectral coefficient vector The user device can transmit the low-dimensional spectral coefficient vector to the central device. The central device can receive the low-dimensional spectral coefficient vector and project it back to the original channel space with channel spatial bases .

[0225] If the channel spatial bases are generated by an AI model (e.g., a DNN), both the central device and the user device in S701 should align with and .

[0226] In some possible implementations, as shown in Figure 15 both the central device and the user device can use a matrix ​​channel space bases ( × ) are down-sampled to × , where . If the matrix defines a sparse pilot pattern , then the matrix is much smaller than the channel space bases . Therefore, the matrix can be regarded as a compact channel space base. The sparse down-sampling is a hash function to ensure that no one can reconstruct the channel space bases from the matrix . Therefore, both the central device and the user devices can use the matrix as a substitute of the channel space bases . The central device can configure and inform the user devices the matrix instead of the channel space bases .

[0227] The user devices can directly obtain the low-dimensional spectral coefficient vectors from the channel estimates on the received pilots: where is the left pseudo-inverse of . If the common information is represented as a basis of row vectors, e.g. , then is the right pseudo-inverse of . Alternatively, the central device can configure and inform the user devices the matrix instead of the channel space bases . The matrix and the matrix are other forms of the above common information.

[0228] In some implementations, to minimize the pilot and channel measurement feedback overhead, both the central device and the user devices preferably align through a random seed, a pseudo-random generating pilot placement function and . In a T-MIMO scenario, the BS as the central device broadcasts or multicasts the common pilot pattern as a control load in the DL channel with a random seed and , and transmits pilots according to the common pilot pattern. The candidate UEs as the user devices will obtain the common pilot pattern and the inverse matrix of the compact channel space bases , demodulate the pilots according to the pilot pattern, estimate the channel coefficients on the pilots, and compute the spectral coefficients Optionally, the user device can send feedback information indicating the spectral coefficients to the central device in the UL immediately after obtaining the spectral coefficients as control load.

[0229] In some of the above embodiments, the central device is shown as a transmitting device and the user device is shown as a receiving device. In other embodiments, the user device is a transmitting device and the central device is a receiving device.

[0230] The following examples are combined with Figure 16 to illustrate how the user device selects the one or more reference channels mentioned in S520 of the method 500, Figure 16 A schematic flowchart of the method 900 is shown. The method 900 can be performed after S520. The method 900 comprises steps S901 to S903. The following disclosure gives an example of the matrix as a pilot pattern and an example of the matrix as common information related to the first set of environmental parameters.

[0231] In S901, the user device determines the DL channel.

[0232] For example, the DL channel can be considered as an example of the DL channel in the method 500.

[0233] For example, the central device can transmit pilots in the DL channel on the positions indicated by the matrix.

[0234] In S902, the user device estimates the DL channel to determine channel measurements.

[0235] In some implementations, the user device estimates channel coefficients on the pilots on the positions indicated by the matrix and obtains a channel estimation result expressed as a vector . The user device can compute low-dimensional spectral coefficients by and : . The low-dimensional spectral coefficients can be considered as an example of channel measurements of the DL channel by the user device. In S903, the user device determines the one or more reference channels according to a scoring function and a threshold.

[0236] In S903, the user device determines the one or more reference channels according to a scoring function and a threshold.

[0237] ​​​​In this application, a device, whether a central device or a user device, can measure or score the distance, similarity, or correlation between two reference channels using one or more scoring functions. The device can measure or score the distance in an equivalent low-dimensional space.

[0238] In the channel space base of the device In cases where public information is being represented, the device can use the reference channel. ( × , Projected into a low-dimensional spectral space. For example, the device uses the channel space basis. Reference Channel Projected onto the spectral coefficient vector ( In ×1), where , In particular, if the channel space basis If it is orthogonal or unitary, then , Therefore, the device can be scored using a scoring function. For any two reference channels (e.g.) and The distance (or similarity, or relevance) between the two input reference channels is scored or measured, and the scoring function returns the result of the score function. and The distance (or similarity, or correlation) between them is a scalar measure. If If it is equal change, then ,like Figure 17 As shown, this means that distance can be equivalently measured in a low-dimensional spectral space. The device can use... To represent two reference channels ( and The distance between them.

[0239] In equipment When representing public information, the device can output at the latent layer. A scoring function is used on top of this. Therefore, the scoring function can be derived from another DNN ( ) to achieve, such as Figure 18 As shown, where These are the parameters of the neurons that need to be trained.

[0240] In some implementations, a reference channel can be replaced with a DL channel in the scoring function to determine the distance between the reference channel and the DL channel. For example, the user equipment can determine the distance between the reference channel and the DL channel by providing a scoring function. and common threshold Determine the one or more reference channels: wherein represents a channel measurement of a DL channel, represents a reference channel in the first set of reference channels, one or more is an example of the one or more reference channels in S520. If none is found, then is zero, which means that no reference channel is within a distance less than or equal to .

[0241] a scoring function may be seen as an example of the first scoring function mentioned in the above method 500. The common threshold may be seen as an example of the first threshold mentioned in the above method 500.

[0242] The user equipment can search for the closest reference channel, the second closest reference channel, the third closest reference channel, etc. according to the given scoring function and the common threshold .

[0243] In some implementations, in order to determine the one or more first reference channels from the first set of reference channels, the user equipment (e.g., UE) can receive from the center device (e.g., BS) a pilot pattern (e.g., mentioned in method 800 ), common information related to the first set of environmental parameters (e.g., mentioned in method 700 , mentioned in method 800 ), the first set of reference channels (e.g., mentioned in method 600 , or mentioned in method 700 or ), a scoring function (e.g., defined above ), and a first threshold (e.g., ). For example, the center device can send , , , and to the user equipment implicitly or explicitly (e.g., pre-negotiated) by any of broadcast, multicast or unicast, once or multiple times.

[0244] In one example, as shown in Figure 19 , the center device can send , , or other forms capable of generating , , a scoring function , and a common threshold or an indication thereof to the user equipment separately or simultaneously.

[0245] In another example, the central device can send The de-ranked version, namely, The former ( ) elements, not All Use one element to reduce DL load. For example... Figure 20 As shown, the central equipment can send data to the user equipment individually or simultaneously. , or other entities capable of generating , , Indicators and scoring functions and corresponding common threshold Or the form indicated by it.

[0246] For example, the central device can send within the first transmission cycle. The former ( () elements, and then can be sent in the second transmission cycle. The rest Some or all of the elements in the array. The central device can decide whether to perform a second transmission based on feedback information from the user equipment. For example, the central device can predefine... The interval between the first and second cycles; or, the central device can be predefined. However, the central device may wait for feedback from the user equipment to decide whether to send data in the second transmission cycle; alternatively, the central device may broadcast or multicast data in the first transmission cycle and then multicast or unicast data to certain user equipment in the second transmission cycle, or not send feedback.

[0247] For example, such as Figure 21 As shown, the central device can transmit within the first transmission cycle or send... or The front of the middle A reference channel is provided, and then the central device can send data during the second transmission cycle. or The rest A reference channel, either partially or entirely. The central equipment can decide whether to perform a second transmission based on feedback from the user equipment. For example, the central equipment can perform a second transmission within the first transmission cycle. or Random selection Each sample. For example, the central equipment can select based on channel conditions associated with the user equipment or user equipment group. For example, if the central device knows the approximate location of one or more user equipments, it can determine the location within the first transmission cycle. or Select Each reference channel allows the central device to select a reference channel closer to the user equipment or the group of user equipment. For example, Figure 22 The reference channel shown is There are several reference channels. If UE-1 is one of the user equipments, the circled reference channels can be considered as selected based on the approximate location of UE-1. An example of a reference channel.

[0248] In certain scenarios, the central device may be associated with a first set of environmental parameters and a second set of environmental parameters. The first and second sets of environmental parameters may partially overlap or not. The first and second sets of environmental parameters may differ in at least one aspect: frequency band, spatial region, weather, data traffic, duplex mode, time or duration, and precoder. Differences between the first and second sets of environmental parameters may lead to differences between a first set of reference channels and a second set of reference channels associated with the second set of environmental parameters. Differences between the first and second sets of environmental parameters may also lead to differences between information related to the first and second sets of environmental parameters.

[0249] Figures 23 to 25 Examples of environmental parameter sets associated with the central equipment are shown. Figure 23 and Figure 24 As shown, environment #1 illustrates an example of the first set of environment parameters, and environment #2 illustrates an example of the second set of environment parameters. Figure 23 In this context, two sets of environmental parameters are associated with two partially overlapping spatial regions. Figure 24 In this context, two sets of environmental parameters are associated with a spatial region. For example... Figure 25 As shown, the central device can be associated with one or more of three sets of environmental parameters, including environment #1, sub-environment #2, and sub-environment #3. The spatial region associated with environment #1 includes the spatial regions associated with sub-environment #2 and sub-environment #3.

[0250] The set of environmental parameters associated with the central device can change over time. For example, the set of environmental parameters can change from a first set of environmental parameters to a second set of environmental parameters. Thus, the central device needs to determine the set of environmental parameters that is currently associated with it in order to determine a set of reference channels and information associated with the current set of environmental parameters for the user devices to report information of their DL channels. For example, the central device can determine the first set of environmental parameters based on any one of the following factors: frequency band, spatial region, weather, data traffic, duplex mode, time or duration, precoder, etc.

[0251] For example, represents the set of environmental parameters that varies depending on the frequency band, spatial region, weather, data traffic, duplex mode, time or duration, precoder, etc. According to , the central device can represent a given set of environmental parameters with the following: a channel space basis indicating common information a matrix indicating pilot patterns a set of reference channels a scoring function a common threshold.

[0252] In some implementations, one central device can have one or more sets of common information, each set of common information associated with one set of environmental parameters. That is, one central device can have multiple sets of common information associated with multiple sets of environmental parameters in one or more spatial regions. For example, the central device can have one or more of the following: 1) one set of common information associated with the first set of environmental parameters and / or the second set of environmental parameters.

[0253] 2) two sets of common information, including a first set of common information and a second set of common information, each set of common information associated with one set of environmental parameters. The first set of common information is associated with wireless channels between the central device and multiple user devices located in a first spatial region; the second set of common information is associated with wireless channels between the central device and multiple user devices located in a second spatial region. The two spatial regions can be partially overlapping or non-overlapping, and can be adjacent or separated, and the spatial regions can be designated as sectors.

[0254] 3) two pieces of common information, including a first piece of common information and a second piece of common information, each piece of common information being associated with a set of environmental parameters. The first piece of common information is associated with a wireless channel between the central device and a plurality of user devices located in a first spatial region; the second piece of common information is associated with a wireless channel between the central device and a plurality of user devices located in a second spatial region. The first spatial region can include the second spatial region. Thus, the two pieces of common information can be applied to user devices located in the same spatial region.

[0255] 4) two pieces of common information, including a first piece of common information and a second piece of common information, each piece of common information being associated with a set of environmental parameters. The first piece of common information is associated with a wireless channel between the central device and a plurality of user devices to which the central device can apply a first Tx precoder; the second piece of common information is associated with a wireless channel between the central device and a plurality of user devices to which the central device can apply a second Tx precoder. The central device can apply both Tx precoders to the user devices, and thus the two pieces of common information can be applied to the user devices.

[0256] 5) two pieces of common information, including a first piece of common information and a second piece of common information, each piece of common information being associated with a set of environmental parameters. The first piece of common information is associated with a wireless channel between the central device and a plurality of user devices, which is transmitted on a first wireless frequency band; the second piece of common information is associated with a wireless channel between the central device and a plurality of user devices, which is transmitted on a second wireless frequency band. The two wireless frequency bands can overlap or not overlap, and can be adjacent or separated.

[0257] 6) two pieces of common information, including a first piece of common information and a second piece of common information, each piece of common information being associated with a set of environmental parameters. The first piece of common information is associated with an UL wireless channel between the central device and a plurality of user devices; the second piece of common information is associated with a DL channel between the central device and a plurality of user devices.

[0258] In some implementations, the common information can change over time. For example, when the set of environmental parameters associated with the central device changes from a first set of environmental parameters to a second set of environmental parameters, the common information also changes, and the central device can further transmit, to the user devices, information associated with the second set of environmental parameters to obtain new feedback information associated with the reference channel from the user devices.

[0259] In some implementations, the method 500 can further include S530. In S530, the central device transmits, to the user devices, third information associated with the second set of environmental parameters, the third information indicating one or more of a second pilot pattern and a second compression function; the second compression function being used to determine one or more of: one or more reference channels in the set of reference channels, and a channel measurement of a second DL channel of the user devices.

[0260] In some scenarios, the scoring function and the threshold can be pre-agreed, thus the scoring function related to the second set of environment parameters can be the same as the first scoring function, the threshold related to the second set of environment parameters can be the same as the first threshold. In addition, the set of reference channels related to the second set of environment parameters can be similar to the set of reference channels related to the first set of environment parameters. However, the pilot pattern (e.g., the or ) that affects the compact channel space basis (e.g., ) mentioned in the method 800 can be different between the first set of environment parameters and the second set of environment parameters. Thus, the central device can need to inform the user device of the second pilot pattern, and the central device can also need to inform the user device of the second compression function, especially when the second compression function is determined by the second pilot pattern.

[0261] For example, the central device has the , the first pilot pattern can be ; the first compression function can be determined according to (or ). The central device has the , the pilot pattern related to the second set of environment parameters can be , the compression function related to the second set of environment parameters can be determined according to (or ).

[0262] In the detailed design, the second pilot pattern can include , and the second compression function can include .

[0263] In some implementations, the second set of environment parameters includes the first set of environment parameters; the second pilot pattern indicates a part that changes between the pilot pattern related to the first set of environment parameters and the pilot pattern related to the second set of environment parameters; and the second compression function indicates a part that changes between the compression function related to the first set of environment parameters and the compression function related to the second set of environment parameters.

[0264] In some scenarios, including the first set of environment parameters in the second set of environment parameters can be interpreted as a part of the second set of environment parameters overlapping with the first set of environment parameters. In one example, the first set of environment parameters and the second set of environment parameters are respectively related to the Figure 25The two spatial regions shown in sub-environment #2 and environment #1 are related, with some overlap. In another example, the first and second environmental parameter sets share the same spatial region. Furthermore, the first and second environmental parameter sets may be related to one or more of the same factors such as frequency band, duplex mode, time or duration, precoder, weather, and data traffic.

[0265] In an exemplary detailed design, the set of reference channels associated with the second set of environmental parameters can be the same as the first set of reference channels. However, if the second set of environmental parameters is more complex than the first set of environmental parameters, the pilot pattern... More locations may need to be indicated as pilots. The location can include Location: and corresponding Therefore, the second pilot pattern may include The second compression function may include By sending and / or This can reduce signaling overhead.

[0266] In some implementations, when the central device determines that the channel condition has changed from the first channel condition to the second channel condition, it sends third information to the user equipment. The first channel condition is related to a first set of environmental parameters, such as... Figure 24 The environment #1 shown is related to the second channel condition and the second environment parameter set, such as Figure 24 The environment shown is #2. For example, the first environmental parameter set is related to the traffic pattern, and the second environmental parameter set is related to the non-traffic pattern; or, the first environmental parameter set is related to the snow pattern, and the second environmental parameter set is related to the non-snow pattern; or, the RBG resolution related to the first environmental parameter set is 1 RBG = 4 RBs, and the RBG resolution related to the second environmental parameter set is 1 RBG = 16 RGs; or, the operating frequency band related to the first environmental parameter set is 10 GHz, and the operating frequency band related to the second environmental parameter set is 12 GHz.

[0267] For example, such as Figure 26 As shown, the central device can send information related to the first environmental parameter set when or after determining the first environmental parameter set, and send information related to the second environmental parameter set when or after determining the second environmental parameter set.

[0268] In other implementations, when the central device estimates or predicts that the channel conditions of the user equipment change from a first channel condition to a second channel condition, it sends third information to the user equipment. The first channel condition is related to a first set of environmental parameters, such as... Figure 23The second channel condition is related to a second set of environmental parameters, as shown in Figure 23 Environment #2, as shown.

[0269] In some implementations, the center device sends the third information to the user device when the current channel condition comprises the first channel condition and the second channel condition, wherein the first channel condition is related to a first set of environmental parameters, and the second channel condition is related to a second set of environmental parameters, as shown in Figure 25 Environment #1, the second channel condition is related to a second set of environmental parameters, as shown in Figure 25 Sub-Environment #2. For example, the first set of environmental parameters is related to a traffic pattern of a spatial region A, and the second set of environmental parameters is related to a snow day pattern of the spatial region A. Optionally, the center device sends the third information to the user device when the center device estimates or predicts that the channel condition of the user device changes from the first channel condition to the second channel condition.

[0270] For example, the center device can send the information related to the first set of environmental parameters and the information related to the second set of environmental parameters in different periods when the center device determines that the current channel condition comprises the first channel condition and the second channel condition, as shown in Figure 26 . Optionally, the center device can send the information related to the first set of environmental parameters and the information related to the second set of environmental parameters in the same period, e.g., in the same message or in several different messages, as shown in Figure 27 . For details about the specific way of transmitting the information related to the first set of environmental parameters and the information related to the second set of environmental parameters, see Figures 19 to 21 .

[0271] In some scenarios, the change from the first channel condition to the second channel condition results in a change of a set of reference channels related to the current set of environmental parameters. For example, the set of reference channels related to the current set of environmental parameters can change from a first set of reference channels related to the first set of environmental parameters to a second set of reference channels related to the second set of environmental parameters. In other scenarios, the current channel condition related to the center device comprises the first channel condition and the second channel condition, and the second set of reference channels related to the second set of environmental parameters is different from the first set of reference channels.

[0272] Therefore, the center device can send fourth information to the user device, which indicates the second set of reference channels related to the second set of environmental parameters.

[0273] The center device can send the third information and the fourth information to the user device respectively or simultaneously.

[0274] In some implementations, the scoring function and the threshold value can not be pre-negotiated. For example, the second scoring function can be determined according to the second set of environmental parameters, and the threshold value can vary with the set of environmental parameters. The third information further indicates one or more of the second scoring function or the second threshold value; the second scoring function is used to determine a distance between the DL channel of the user device and one of the second set of reference channels; and the second threshold value is used to determine one or more of the second set of reference channels.

[0275] In some implementations, the method 500 further includes S540, which can be performed after S510 and S520. In S540, the user device sends, to the central device, fifth information indicating the first reference channel, wherein a distance between the first reference channel and the DL channel of the user device is less than or equal to the third threshold value, and the one or more reference channels include the first reference channel.

[0276] The method of determining the first reference channel is described in detail in method 900. Here, no further description is given.

[0277] The third threshold value can be the same as the first threshold value.

[0278] In some implementations, the fifth information includes an index of the first reference channel. For example, the fifth information includes an index of the nearest reference channel; the fifth information can further include an index of the second nearest reference channel. The fifth information can further include the distance between the DL channel and the first reference channel.

[0279] In some other implementations, the channel condition of the user device can be different from the channel condition related to the first set of environmental parameters. For example, the user device is moving out of a certain area related to the first set of environmental parameters, or the user device is moving out of a certain wireless channel related to the first set of environmental parameters. Therefore, there can be no reference channel in the first set of reference channels that has a sufficient similarity to the DL channel. At this time, the user device can send twelfth information indicating that there is no reference channel whose distance to the DL channel is less than or equal to the first threshold value. The twelfth information can further include the nearest distance between the DL channel and a reference channel in the first set of reference channels.

[0280] In some other implementations, if the user device determines that there is no reference channel whose distance to the DL channel is less than or equal to the first threshold value, the user device does not send any feedback information (e.g., the twelfth information) to the central device. In some embodiments, if the central device does not receive the feedback information of the user device within a certain time, the central device will ignore the user device when selecting the user device for pairing.

[0281] In some detailed designs, S540 can be performed before S530, can be performed synchronously with S530, or can be performed after S530.

[0282] For example, when S540 is performed after S530, the first set of reference channels can include the second set of reference channels. As shown in Figure 28 The center device can receive the fifth information after transmitting the first information, the second information, and the third information. The first information indicates the first set of reference channels. The second information indicates one or more of the first pilot pattern, the first compression function, the first scoring function, and the first threshold. The third information indicates the second pilot pattern and / or the second compression function.

[0283] For another example, when S540 is performed after S530, the center device is related to both the first set of environmental parameters and the second set of environmental parameters. The center device can receive the fifth information when the distance between the first reference channel and the DL channel is less than the closest distance between a reference channel in the second set of reference channels and the DL channel. The center device can also receive the fifth information when the distance between the first reference channel and the DL channel is less than or equal to the third threshold, and no distance between any reference channel in the second set of reference channels and the DL channel is less than or equal to the threshold. As shown in Figure 29 The center device can receive the fifth information after transmitting the first information, the second information, the third information, and a fourth information, where the first information, the second information, and the third information are the same as mentioned above. The fourth information indicates the second set of reference channels. The content of the first information, the second information, the third information, the fourth information, the fifth information, and the sixth information are described in detail in the above embodiments. Here, no further description is given.

[0284] In some implementations, the method 500 further includes that the user device transmits, to the center device, a sixth information indicating a second reference channel in the second set of reference channels, where the distance between the second reference channel and the DL channel of the user device is less than or equal to a fourth threshold.

[0285] For example, the center device transmits the third information and the fourth information to the user device when determining that the channel condition changes from the first channel condition to the second channel condition, and then receives the sixth information. As shown in Figure 30 The center device can receive the sixth information after transmitting the first information, the second information, the third information, and the fourth information. The first information, the second information, the third information, and the fourth information are the same as mentioned above.

[0286] The fourth threshold can be the same as the second threshold.

[0287] The form of the sixth information can be the same as the form of the fifth information. The detailed description of the sixth information is described in the above embodiments about the fifth information.

[0288] In some implementations, the user device transmits information indicating that no reference channel is determined to have a distance to the DL channel less than or equal to a fourth threshold. The information can also include a closest distance between the DL channel and a reference channel in the second set of reference channels.

[0289] In some implementations, the central device transmits the sixth information and does not transmit the fifth information when the distance between the second reference channel and the DL channel is less than a closest distance between a reference channel in the first set of reference channels and the DL channel.

[0290] For example, the central device is associated with both the first set of environmental parameters and the second set of environmental parameters. Then, the central device can receive the sixth information when the distance between the second reference channel and the DL channel is less than a closest distance between a reference channel in the first set of reference channels and the DL channel. For another example, the central device is associated with both the first set of environmental parameters and the second set of environmental parameters. Then, the central device can receive the sixth information when the distance between the second reference channel and the DL channel is less than or equal to the fourth threshold and no reference channel in the first set of reference channels has a distance to the DL channel less than or equal to the threshold. For example, as shown in Figure 29 The first information, the second information, the third information, and the fourth information are the same as mentioned above.

[0291] In some implementations, the central device transmits both the fifth information and the sixth information, the method 500 further includes: the central device transmitting, to the user device, seventh information indicating a first distance between the first reference channel and the DL channel and eighth information indicating a second distance between the second reference channel and the DL channel, the first distance and the second distance being used to determine a set of environmental parameters from the first set of environmental parameters and the second set of environmental parameters for the user device to pair with.

[0292] The seventh information and the eighth information can be carried by the same message.

[0293] For example, when the first distance is less than the second distance, the central device determines that the first set of environmental parameters is used for the user device to pair with; or, when the first distance is less than the second distance, the central device determines that the second set of environmental parameters is used for the user device to pair with; or, when the first distance is equal to the second distance, the central device determines that either of the first set of environmental parameters and the second set of environmental parameters is used for the user device to pair with.

[0294] For example, the central device is associated with both the first set of environmental parameters and the second set of environmental parameters, the central device can receive the fifth information and the sixth information, and then the central device can also receive the seventh information and the eighth information. For example, as shown in Figure 31 The central device can receive the seventh information and the eighth information after receiving the fifth information and the sixth information.

[0295] In some implementations, the first set of reference channels is determined according to a location of the user equipment or channel conditions related to the user equipment. For example, the central device can know some approximate locations of a user equipment or a set of user equipments from a perception or positioning system, and the central device can infer which wireless environment the user equipment or the set of user equipments belongs to according to the approximate locations; the central device can select the part of the environment that is closer to the estimated locations of the user equipment or the set of user equipments. In a detailed design, the first set of reference channels can include the reference channels mentioned in the method 900.

[0296] In some detailed designs, the set of environment parameters related to the central device or the user equipment can change frequently. In the technical solutions provided in this application, when it is determined that the set of environment parameters changes, the information related to the set of environment parameters, such as the pilot pattern and the compression function, is updated, or when it is determined that the central device is related to both the first set of environment parameters and the second set of environment parameters, the information related to the second set of environment parameters is sent, which can ensure the effectiveness of the reference channels related to the set of environment parameters reported by the user equipment and improve the communication efficiency. For example, it can be avoided that when the set of environment parameters related to the central device has changed to the second set of environment parameters, the user equipment still reports the reference channels related to the first set of environment parameters.

[0297] The above-mentioned methods 500, 600, 700, 800 and 900 are described respectively, and the above-mentioned methods 500, 600, 700, 800 and 900 can be used alone or in combination.

[0298] The communication method of the embodiments of the application is described in detail above, and the communication device of the embodiments of the application will be described below with reference to Figures 5 to 31 and Figure 32 and 33 The communication device of the embodiments of the application is described in detail.

[0299] Figure 32 is a schematic block diagram of the communication device 10 of the embodiments of the application. As shown in Figure 32 , the communication device 10 includes a transceiver module 11. Optionally, the communication device 10 also includes a processing module 12. The transceiver module 11 can implement corresponding communication functions, and the processing module 12 is used for data processing. The transceiver module 11 can also be referred to as a communication interface or a communication unit.

[0300] In some embodiments, the communication device 10 can also include a storage module. The storage module can be used to store instructions and / or data. The processing module 12 can read the instructions and / or data in the storage module to enable the communication device to implement the above-mentioned method embodiments.

[0301] The communication apparatus 10 can be configured to perform the actions performed by the center device in the above method embodiments. In this case, the communication apparatus 10 can be the center device or a component configured in the center device. The transceiver module 11 is configured to perform the transceiver related operations on the center device side in the above method embodiments. The processing module 12 is configured to perform the processing related operations on the center device side in the above method embodiments.

[0302] Alternatively, the communication apparatus 10 can be configured to perform the actions performed by the user device, e.g., by the user device in the above method embodiments. In this case, the communication apparatus 10 can be the user device or a component configured in the user device. The transceiver module 11 is configured to perform the transceiver related operations on the user device side in the above method embodiments. The processing module 12 is configured to perform the processing related operations on the user device side in the above method embodiments.

[0303] In one design, the communication apparatus 10 is configured to perform the actions performed by the center device in the above method embodiments.

[0304] In some implementations, the transceiver module 11 is configured to send, to the user device, first information indicating a first set of reference channels related to the first set of environmental parameters; and the transceiver module 11 is further configured to send, to the user device, second information related to the first set of environmental parameters, the second information being used to determine one or more reference channels from the first set of reference channels.

[0305] In another design, the communication apparatus 10 is configured to perform the actions performed by the user device in the above method embodiments.

[0306] In some implementations, the transceiver module 11 is configured to receive, from the center device, first information indicating a first set of reference channels related to the first set of environmental parameters; and the transceiver module 11 is further configured to receive, from the center device, second information related to the first set of environmental parameters, the second information being used to determine one or more reference channels from the first set of reference channels.

[0307] In some other implementations, the transceiver module 11 is configured to receive, from the center device, first information indicating a first set of reference channels related to the first set of environmental parameters; and the processing module 12 is configured to determine whether a distance between a first reference channel in the first set of reference channels and a DL channel of the user device is less than or equal to a first threshold.

[0308] The specific process by which each unit performs the corresponding steps is described in detail in the above method embodiments. For brevity, the details are not repeated here.

[0309] Reference Figure 33 , Figure 33is a schematic block diagram of another communication apparatus of embodiments of the present application. The communication apparatus 20 comprises a processor 21. The processor 21 is coupled with a memory 23. The memory 23 is used to store computer programs or instructions and / or data. The processor 21 is used to execute the computer programs or instructions and / or data stored in the memory 23 to perform the methods in the above method embodiments.

[0310] In some embodiments, the communication apparatus 20 comprises one or more processors 21.

[0311] In some embodiments, as shown in Figure 33 the communication apparatus 20 can further comprise a memory 21.

[0312] In some embodiments, the communication apparatus 20 can comprise one or more memories 23.

[0313] In one example, the memory 23 can be integrated with the processor 21, or disposed separately from the processor 21.

[0314] In one example, as shown in Figure 33 the communication apparatus 20 can further comprise a transceiver 22, which is used to receive and / or send signals. For example, the processor 21 is used to control the transceiver 22 to receive and / or send signals.

[0315] In one aspect, the communication apparatus 20 is used to perform operations performed by the center device in the above method embodiments.

[0316] For example, the processor 21 is used to perform processing related operations performed by the center device in the above method embodiments, and the transceiver 22 is used to perform transceiving related operations performed by the center device in the above method embodiments.

[0317] In another aspect, the communication apparatus 20 is used to perform operations performed by the user device in the above method embodiments.

[0318] For example, the processor 21 is used to perform processing related operations performed by the user device in the above method embodiments, and the transceiver 22 is used to perform transceiving related operations performed by the center device in the above method embodiments.

[0319] The processor 22 can be an integrated circuit chip with processing capability. In implementation process, each step of the above method embodiments can be realized through hardware integrated logic circuit in the processor or through instructions in the form of software. The processing module 12 can be a general processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. All methods, steps and logic block diagrams disclosed in the embodiments of the present application can be realized or executed by the processor. The general processor can be a microprocessor, or the processor can be any conventional processor. The steps of the method disclosed in the embodiments of the present application can be directly executed and completed by the hardware decoding processor, or executed and completed by using a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium known in the art such as a random access memory, a flash memory, a read only memory, a programmable read only memory, an electrically erasable programmable memory or a register. The storage medium is located in the memory, and the processor reads the information in the memory and combines the hardware of the processor to complete the steps of the above method.

[0320] It can be understood that the memory 23 in the embodiments of the present application can be a volatile memory or a non-volatile memory, and can also include a volatile memory and a non-volatile memory. The non-volatile memory can be a ROM, a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically EPROM (EEPROM), or a flash memory. The volatile memory can be a RAM used as an external cache. By way of example and not limitation, many forms of RAM can be used, such as a Static RAM (SRAM), a Dynamic RAM (DRAM), a Synchronous DRAM (SDRAM), a Double Data Rate SDRAM (DDR SDRAM), an Enhanced SDRAM (ESDRAM), a Synch Link DRAM (SLDRAM), and a Direct Rambus RAM (DR RAM). The storage of the system and method described in the specification is intended to include but not limited to these and any other suitable storage.

[0321] The embodiments of the present application also provide a system. The system includes the central device and the user device in the above embodiments.

[0322] The embodiments of the present application also provide a computer storage medium, which can store program instructions to execute any of the above methods.

[0323] Optionally, the storage medium can be specifically the memory 23.

[0324] Those skilled in the art will appreciate that, in connection with the description of the examples described in the embodiments disclosed in the specification, each unit and algorithm steps can be implemented by electronic hardware, or by a combination of computer software and electronic hardware. Whether the function is performed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but it should not be considered that the embodiments exceed the scope of the present application.

[0325] Those skilled in the art can understand that, for the convenience and brevity, the detailed working process of the above system, device and unit can refer to the corresponding process in the above method embodiments, which will not be described herein.

[0326] In several embodiments provided in the present application, the disclosed system, device and method can be implemented in other ways. For example, the device embodiments described are only examples. For example, the unit division is a logical function division, and other division methods can also be adopted in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be omitted or not executed. In addition, the display or description of mutual coupling or direct coupling or communication connection can be realized through various communication interfaces. The indirect coupling or communication connection between devices or units can be realized through electronic, mechanical or other forms.

[0327] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, these components can be located in one unit, or can be distributed in multiple network units. Some or all units can be selected according to actual needs to achieve the purpose of the embodiments.

[0328] In addition, the functional units in the embodiments of the present application can be integrated into one processing unit, or each unit can exist physically independently, or two or more units can be integrated into one unit.

[0329] When these functions are implemented in the form of software functional units and sold or used as independent products, these functions can be stored in a computer readable storage medium. The technical solutions of the present application can be realized in the form of a software product. The software product is stored in a storage medium and includes a plurality of instructions for instructing a computer device (which can be a personal computer, a server or a network device, etc.) to execute all or part of the steps of the method described in the embodiments of the present application. The storage medium described above includes a U disk, a mobile hard disk, a ROM, a RAM, a magnetic disk, an optical disk, etc. any medium that can store program codes.

[0330] The above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any changes or replacements within the technical scope disclosed in the present application can be easily thought of by those skilled in the art, and is within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0331] Spatial reference channel adaptive updating method for MU-MIMO pairing Abbreviations

[0332] MIMO and MU-MIMO MIMO systems have been widely applied in modern wireless systems, and the system capacity and bandwidth efficiency are improved by utilizing the spatial diversity between antenna ports. For example, on a given subcarrier or RE, the system capacity is improved by A transmitter consisting of Tx antenna ports and a transmitter consisting of... A receiver consisting of Rx antenna ports forms a unit × MIMO channel, by × Complex matrix This indicates that it can be decomposed using SVD [4]: ,in yes × Square orthogonal matrix (where ), yes × Square orthogonal matrix (where ), yes × A rectangular diagonal matrix. rank ( (Not greater than) and The smaller one between them, i.e. According to the standard SVD, if the transmitter applies a precoding matrix... The receiver uses a receiving matrix. ,but × MIMO channels will become The mathematical expression for the independent and parallel (orthogonal) sub-channels is as follows: .

[0333] Each subchannel has a scaled channel response. ),Right now The i-th diagonal element (singular value, Accordingly, the SNR on the i-th sub-channel is defined as follows: In wireless systems, only sub-channels with a signal-to-noise ratio (SNR) above a certain threshold are considered valid for transmission. These valid sub-channels are called MIMO streams.

[0334] The SNR-based truncated MIMO decomposition scheme decomposes standard SVD into reduced-rank SVD by discarding sub-channels with SNR below a threshold. (Decreased Rank SVD in [4]), where yes × Orthogonal matrix (where ), yes × Orthogonal matrix (where ), is × a square diagonal matrix. The number of MIMO streams is When the transmitter applies a precoding matrix and the corresponding receiver applies a receiving matrix , × The MIMO channel will become: .

[0335] For rank-reduced SVD, is × a square diagonal matrix.

[0336] Mathematically, the precoding matrix at the transmitter and the receiving matrix at the receiver are obtained by performing a linear transformation on the MIMO channel to coordinate the entire MIMO channel on the effective sub-channels. The MIMO gain or spatial diversity gain, denoted by SNR , is due to the spatial diversity inherent in the MIMO channel between the transmitter and the receiver, which is related to the wireless environment. Empirically, a wireless channel in a complex environment such as a downtown area will have more MIMO streams than in a simple rural environment, because the high-rise buildings in the downtown area create more spatial diversity through stronger radio reflectivity.

[0337] To achieve higher MIMO gain, a wireless system will increase the number of antenna ports, i.e. and , thereby raising the upper limit of the potential number of MIMO streams, because . However, in reality, is much smaller than its upper limit . This motivates the deployment of MU-MIMO: if the number of MIMO streams from one MIMO channel of one user is insufficient, multiple MIMO channels from multiple users can be multiplexed by a common precoder . Suppose that two MIMO channels and on the same RE are very different from each other; then it is likely that a common precoder can be found to multiplex (separate) the two; and suppose that two MIMO channels and on the same RE are almost the same; then it is less likely that a common precoder can be found to multiplex (separate) the two.

[0338] Mathematically, such a common precoder is a linear combination of the precoders and In practice, the method widely used is based on EZF. By concatenating the two precoders in the reduced rank SVD on the MIMO channel into one, where is a matrix. In EZF, their common precoder is where is a matrix. If and are orthogonal to each other, then is close to the identity matrix , which means the transmitter can continue to use the precoding matrix of UE-1 and the precoding matrix of UE-2 to multiplex on the same RE simultaneously without MAI. If and are the same, then approximates a singular matrix (non-invertible), so no common precoder is available. These two UEs cannot be paired. In practice, most cases are in between these two extremes. neither an identity matrix nor a singular matrix. The transmitter has to compute common precoders for all possible combinations and then find the best one. However, this is an NP-hard problem. Suppose a transmitter has 200 candidate receivers. In theory, for different receiver combinations, the transmitter needs to traverse times different common precoders computation. Moreover, to improve the degree of approximation to the identity matrix and pair or group more receivers, we usually have , prompting wireless systems to employ more antenna ports between the transmitter and the receiver, or more precisely, higher MIMO antenna port ratios ( ).

[0339] After computing the common precoder , the transmitter multiplies it by the signal it transmits.

[0340] MU-MIMO engineering trade-offs For wireless systems, MU-MIMO is usually used in DL, where the BS is the transmitter and the UE is the receiver. The MIMO channels of multiple UEs are paired by a common precoder to multiplex on the same RE (frequency) and the same time duration (timing).

[0341] To achieve higher throughput and system efficiency, modern MU-MIMO systems deploy a large number of antenna ports over a wider frequency band. For example, in a T-MIMO system (of 6G), a BS is expected to have 3072 antenna ports, while a UE has 64 antenna ports over a 400MHz bandwidth. The MIMO channel becomes a three-dimensional tensor × × ).

[0342] Main trade-off #1: DL / UL channel reciprocity assumption While MU-MIMO should be paired over the DL channel between a BS and multiple UEs, it is not practical for each candidate UE to report or feedback its DL channel estimate to the BS, because this would result in a huge UL feedback overhead in the case of a T-MIMO channel with high-dimensional properties. In a TDD system, it is assumed that the DL channel between a BS and a UE can be approximated by the UL channel between the BS and the UE. In 4G and 5G-NR systems, the SRS UL channel is designated for UL channel measurement or estimation for this purpose. The SRS UL channel is shared by multiple UEs. These UEs send their own SRS reference signals at SRS pilot locations, and the BS can estimate its own UL MIMO channel separately. In 5G-NR, sharing is achieved by code multiplexing the modulated signals.

[0343] Main trade-off #2: Random or quasi-random MU pairing implementation As mentioned before, MU pairing is an NP-hard problem. Theoretically, the optimal pairing is the result of an exhaustive search (computation) of all possible combinations of candidate UEs (from two to all). However, the computation involving the pseudo-inverse of a large matrix is too long for real-time signal processing during a TTI or a few TTIs. In particular, when more than a few hundred or even a few thousand UEs are involved and 10 or 20 UEs are paired in a few TTIs, the pseudo-inverse of the matrix may be too complex to compute for most hardware implementations. Due to complexity, storage, and latency constraints, an exhaustive search for the optimal pairing scheme is not allowed in practical implementations. Instead, a fixed number of paired UEs is first randomly or quasi-randomly selected from a large pool of candidates into , and then the common precoding matrix EZF computation is performed. The selection can take into account the positions of the candidate UEs, for example. For example, an empirical selection algorithm can tend to select paired UEs that are far apart from each other, as these UEs are more likely to have orthogonal MIMO channels. The number of pairs is simply given by empirical, system, or hardware constraints, for example.

[0344] Strictly speaking, the trade-off does not realize pairing, but only from the reversible Computing precoding matrices .

[0345] 5G-NR SRS UL and CSI-RS acquisition of DL MIMO channel 5G-NR uses the SRS UL channel to measure the UL MIMO channel between the BS (as a transmitter) and multiple UEs (as receivers). The BS will assume the UL MIMO channel it measures or estimates from its SRS UL channel as the DL MIMO channel between the BS and UEs in TDD mode.

[0346] Specifically, the SRS UL channel defines a set of uniform pilot (or reference signal) placement or location patterns in terms of REs (frequency), BS antenna ports, and UE antenna ports. The 5G-NR standard specifies the uniform pilot placement patterns that the BS and UE must follow. One of the reasons for the standardization of the uniform pilot placement patterns is its simplicity, i.e., only a few parameters are exchanged between the transmitter and receiver to align the current patterns with each other.

[0347] In addition, to allow the BS to measure more than one UE at the same time, a code multiplexing scheme is used on the pilots, allowing more than one UE to mask its pilots with different codes to share the same pilot locations. In 5G-NR, the code multiplexing scheme of the SRS UL channel is designed to support up to 16 users. If more than 16 UEs need to share the SRS UL channel, new pilot locations need to be consumed. Thus, 5G-NR has the capability of the SRS UL channel to measure multiple UEs at the same time.

[0348] If the RF and IF parts are considered, the UL / DL channels are not always reciprocal. For example, the RF component of the BS is designed for higher Tx power than the RF component of the UE, resulting in a larger DL coverage than UL coverage, as shown in Figure 34 .

[0349] The UL received signal strength from the UEs at the cell edge to the BS can be too weak to estimate. These UEs need to feedback their DL MIMO channel instead of sending their pilots on the SRS UL channel. Therefore, 5G-NR provides them with CSI-RS, i.e., a uniform pilot placement pattern, in the DL channel. The UEs will estimate the channel coefficients on the pilots (RS, reference signal) in the DL channel and then interpolate the entire channel coefficients from the estimated channel coefficients. The UEs will compress the entire channel estimates into CSI and then feedback to the BS in the UL channel. The 5G standard not only defines the pilot placement pattern of the CSI-RS in the DL channel, but also defines the compression method. For example, the CSI includes PMI and RI, which are both indices in a table of pre-configured precoding matrices and ranks. The BS is expected to decompress the CSI into the DL MIMO channel estimates and then facilitate the subsequent MU-MIMO pairing and common precoding computation. In general, the result of the CSI-RS DL channel is the CSI compression, and specifically, the CSI compression or encoder defined in 5G-NR is a lossy compression.

[0350] EZF-based MU-MIMO pairing and precoding matrix computation As described in the background section, the pairing search and the common precoding matrix computation are done together.

[0351] First, the computation of the common precoding matrix needs to be done before all the SVDs on the candidate UEs can be done. In particular, in T-MIMO, for each candidate UE, the BS needs to estimate their MIMO channel from the SRS UL channel or from the CSI feedback and then compute the rank-reduced SVD on a large number of × matrices.

[0352] Second, The pseudo-inverse operation of the is too complex to be done in a few milliseconds. For example, in T-MIMO, is a thousand by hundred complex matrix. It is almost impossible to compute on a large number of candidate in a TTI (1 ms).

[0353] Non-uniform pilot placement pattern 5G-NR SRS UL channels and CSI-RS DL channels both use uniform pilot placement patterns, partly because uniform pilot placement patterns are one of the safest methods to ensure channel estimation performance, especially when there is little a priori knowledge about the current channel, and partly because they are easy to describe, standardize, and align (configure) across transceivers. However, uniform pilot placement patterns are one of the least efficient patterns. Their density design must be based on the worst-case scenario in a statistical sense, which is rarely seen in practice. In other words, in most practical cases, the uniform pilot placement patterns specified in the 5G-NR standard can be over-designed.

[0354] In 5G-NR, the average density of its uniform pilot placement patterns is about 7% to 17% of the wireless resources it uses for pilots or reference signals. For example, placing one reference signal per RB (consisting of 12 consecutive REs) from one transmit antenna port results in 8.33% (about 1 / 12) of pilot overhead. As shown in Figure 35 , if TMIMO employs the same 5G-NR uniform density, the pilot overhead will be too large to handle, or at least prohibit UEs at the cell edge from feeding back their T-MIMO CSI.

[0355] In theory, non-uniform pilot placement patterns based on a priori knowledge of channel distribution will consume less pilot overhead. First, how is the a priori knowledge learned and represented? In [2], a priori knowledge about a high-dimensional signal space (MIMO channels can be considered as high-dimensional signal spaces) is represented using standard orthonormal channel space bases × 1 where, . is the total dimension of the signal space after vectorization. For example, × × The total dimension of a MIMO channel with . is the rank of the environment, which is related to the complexity of the a priori knowledge contained. In mathematics, is the number of principal components of the a priori knowledge.

[0356] [2] proposes to use a data learning method to learn the a priori knowledge. The channel space bases is calculated according to the number of data samples collected or sampled in this environment. [1] also proposes to apply this data learning method in the MIMO case, where is the representation of the common spatial a priori knowledge of MIMO channels within the environment of interest.

[0357] According to the representation of the common channel space bases ( With prior knowledge of the channel matrix H, the near-optimal non-uniform pilot placement pattern can be computed by column rotation QRD [3] on H: . The few "strongest" column rotation pivots (in a typical column rotation QRD, column rotation pivots are ordered by their importance or contribution) in H will indicate the most important or most contributing locations to place reference signals (or pilots) for reconstruction purposes.

[0358] As shown in [1] and [2], The non-uniform pilot placement pattern indicated by the column rotation pivots in H will result in almost minimal pilot overhead while still minimizing the MSE on reconstruction (or decoder, decompression) [6].

[0359] Prior art technical solutions Prior art: SRS sounding UL channel Prior art: CSI-RS DL channel Prior art: EZF-based MU-MIMO pairing and precoding matrix computation Prior art: QRD-based non-uniform pilot placement and compression Drawbacks of prior art 5G-NR SRS UL and CSI-RS for acquisition of DL MIMO channel

[0360] The first major drawback is due to the assumption on UL / DL channel reciprocity. Although the over-the-air part of the MIMO channel can usually satisfy the UL / DL reciprocity assumption (since the mutual information , is the mutual information of two random variables and ), the RF and IF components (analog circuits) usually do not support the UL / DL reciprocity assumption. Therefore, this assumption will inevitably compromise the overall performance. Moreover, this assumption is only valid for TDD mode, not for FDD mode.

[0361] The second major drawback appears when the dimension of the MIMO channel reaches such a large number as T-MIMO Figure 35 . First, the BS needs to estimate the entire MIMO channel for all code-multiplexed UEs on its SRS UL channel. The BS needs to estimate the channel coefficients on each single pilot for each code-multiplexed UE. Then, it has to interpolate the entire MIMO channel from the estimated channel coefficients on the pilots of each UE. Second, it needs to try to pair all active UEs and compute their common precoder. The dimension of a typical T-MIMO limits the storage and computation. ​

[0362] The third main drawback is due to the MAI between the code multiplexed UEs sharing the same SRS UL channel. The MAI is unavoidable. On one hand, it limits the maximum number of code multiplexed UEs (the upper bound capacity); on the other hand, it degrades the accuracy (or performance) of the channel estimation. This is why 5G-NR has to limit the maximum number of UEs sharing the same SRS UL channel. However, in 6G, the upper bound capacity on the SRS UL channel will bring scheduling and overhead, where one BS will accommodate much more active UEs than 5G-NR.

[0363] The fourth main drawback is due to mobility. It is well known that the wireless channel changes significantly when the UE moves. Sometimes, even a small displacement in location causes a loss of LOS, resulting in a huge change in the channel. Since the SRS UL channel is shared among all active UEs and the SRS UL channel has an upper bound capacity, it is not convenient and power consuming for a group of UEs and a BS to perform their SRS-UL channel estimation so frequently. Therefore, SRS UL based MU-MIMO is very sensitive to mobility in real applications.

[0364] The last main drawback is the DL CSI-RS channel involving the cell edge UEs. In fact, the UEs at the cell edge using the CSI-RS suffer from more severe performance loss.

[0365] Prior art: EZF-based MU-MIMO pairing and precoding matrix computation The first drawback is that one has to compute the pseudo-inverse operation [5] for any potential UE pairing possibility of all candidate UEs If a candidate UE is not selected for pairing on the current wireless resource, the wireless resource (SRS UL channel or CSI-RS channel, CSI feedback) allocated to this UE and the computation (channel estimation, SVD, decompression) made for this UE are wasted.

[0366] The second drawback is that one has to compute the pseudo-inverse operation [5] for any potential UE pairing possibility of all candidate UEs , which is the widely used EZF method. If one does not select a set of potential UE pairings (for a certain wireless time-frequency resource, only a set of UE pairings is selected, the rest are discarded), the computation and storage overheads ( ) are wasted.

[0367] The last drawback is that the pairing process and the precoding computation are continuous and tied together: one has to compute the pseudo-inverse operation for each potential UE pairing possibility of all potential UE pairing possibilities Then, a set of potential UE pairs can be selected as the UE pairs to be applied on a certain radio time-frequency resource. After trying all sets of potential UE pairs... Previously, it was impossible to determine the UE pairing to be applied on a certain radio time-frequency resource.

[0368] Prior art: QRD-based non-uniform pilot placement and compression While this method provides a good channel estimation and compression scheme with near-minimum pilot and compression overhead, it still aims to reconstruct the channel as reliably as possible. This objective requires minimizing overhead in terms of the number of reference signals and the compression ratio, both of which require a channel space basis (…). From the perspective of source coding, the common channel space basis ( (This is the codebook that minimizes MSE during reconstruction.) × How much of it This determines how much "details" need to be reconstructed. Due to the channel space basis (… ) is the result of SVD [4], while SVD usually... The columns are sorted in descending order of their corresponding singular values, therefore The first column is more important than the second column (more primary in mathematical terms), and so on. Retaining more columns would provide more “details” about the reconstruction, but from an energy perspective, “details” are not so important.

[0369] In order to achieve non-uniform pilot pattern ( Reconstruct the entire MIMO channel ( The BS and UE should be aligned with a sufficiently large channel space basis ( However, in the TMIMO scenario, and Both are enormous. Furthermore, when a UE moves from one environment to another, it must switch from the current environment... and Update to the new and .

[0370] In some cases, the channel space basis ( It is learned from many data samples, the channel space basis ( The data sample collection and cleaning, as well as the channel space basis (...), are themselves highly IPR entities. The computation of ) is very expensive, especially for high-dimensional data samples. Any data sample with a channel space basis ( The signals of ) can be optimized for non-uniform pilot patterns or even compression schemes.

[0371] Detailed description of the technical solutions of the present application In invention [8], a new method for MIMO pairing is proposed. The concept of spatial reference channel is used here. The BS as the transmitter sends some spatial reference channels to the UE as the receiver. Instead of estimating, compressing and feeding back the whole DL channel, the UE measures the "distance" between its estimated DL channel and multiple spatial reference channels, and then only feeds back the index of the nearest reference channel to the BS; after receiving the indication of the nearest reference channel from multiple UEs, the BS pairs the UEs according to the indication, and then requests the selected UEs to send their channel estimates; finally, the BS calculates the total common precoding matrix of the paired UEs according to the feedback channels of the paired UEs and the indication of the nearest reference channel.

[0372] The spatial reference channel or spatial reference channel set will affect the overall performance. On the one hand, the UE is constantly moving, which may cause some reference channels to become outdated; on the other hand, the wireless channel of the BS may be affected by changing environments (such as weather, traffic, etc.).

[0373] It is not wise to use some static spatial reference channels or spatial reference channel sets in mobile wireless systems. In addition, the spatial reference channels can be divided into different sets, each corresponding to some physical world spatial environment. These environments may be overlapping or non-overlapping, or a larger environment may contain several smaller sub-environments.

[0374] This IPR focuses on how to manage reference channels and / or reference channel sets.

[0375] Summary of the gist of the present application The spatial reference channels are divided into multiple sets. When the UE moves, it constantly feeds back the indication of the nearest spatial reference channel in the set sent to it by the BS.

[0376] According to these successive indications, the BS can predict whether the UE needs a new spatial reference channel set. If so, the BS will update the spatial reference channel set to the UE.

[0377] Dynamic, updated In the following discussion, we will use the T-MIMO wireless channel as an example, because it has the high-dimensional characteristics as shown in Figure 35 In the following, we will abbreviate it as wireless channel or channel. Please remember that the concept of spatial reference (anchoring) channel can be applied to many high-dimensional signal space applications other than T-MIMO.

[0378] Embodiment 1: Obtain multiple pieces of prior knowledge related to a specific environment According to the embodiment 1 of the invention [8], the common (spatial) prior knowledge of the wireless channel related to a specific environment can be acquired and learned in various forms in a data-driven manner. According to the embodiment 3 of the invention [8], one possible form to represent the common prior knowledge is the channel spatial basis , i.e., a unitary matrix.

[0379] Mathematically, with the basis , the original high-dimensional spatial signal can have an equivalent linear representation in the spectral low-dimensional space .

[0380] The basis allows the reference channel to be compressed into its spectral space, as described in the embodiment 8 of the invention [8]. A scoring function is defined in the embodiment 5 of the invention [8], which allows all users to measure the distance between any two channels. More importantly, the scoring function can be done in the low-dimensional spectral space. Accordingly, the scoring function can have a threshold as described in the embodiment 9 of the invention [8]. To save the pilot overhead, the embodiment 6 of the invention [8] proposes a pilot placement pattern, i.e., a sampling matrix , to indicate the locations of the pilots to be transmitted in the DL channel. Moreover, the pilot placement scheme is very sparse. More interestingly, the sampling matrix can further compress the channel spatial basis : . The embodiment 6 of the invention [8] even suggests to directly transmit ( ) to the receiver.

[0381] The embodiment 7 of the invention [8] selects spatial reference channels into the set according to the representative degree, and then the embodiment 8 of the invention [8] compresses them into , where is a ×1 vector. In the embodiment 9 of the invention [8], the BS as the transmitter transmits (broadcasts, groupcasts, or unicasts) to the UE implicitly or explicitly once or multiple times: - , , , , and .

[0382] In the embodiment 9 of the invention [8], the UE can first estimate the channel coefficients on the pilots ; secondly, compute ; then search for the nearest reference channel: , if not found, is zero.

[0383] Invention [8] mentions that there can be multiple sets of spatial reference channels, but it focuses on a single set. In fact, multiple sets of spatial reference channels can originate in different ways.

[0384] - There are multiple pieces of prior knowledge; two pieces of prior knowledge can be related to two different spatial environments; or, two pieces of prior knowledge related to the same spatial environment can be related to different wireless frequency bands; or, two pieces of prior knowledge related to the same spatial environment can correspond to two types of weather: bad weather and good weather; or two pieces of prior knowledge related to the same spatial environment can correspond to two types of time periods, such as midnight and traffic rush hour; - There is only one piece of prior knowledge, but multiple sets of training data samples are generated, and different training data sets result in different .

[0385] - There is one piece of prior knowledge and one set of training data samples, but there are multiple sets of spatial reference channels.

[0386] The BS, as a transmitter or receiver, can have multiple pieces of common prior knowledge related to one spatial environment.

[0387] - Alternative #1: One piece of common prior knowledge for a given frequency band; - Alternative #2: One piece of common prior knowledge for pre-installed Tx precoder (beamforming) - Alternative #3: One piece of common prior knowledge for typical weather conditions; - Alternative #3: One piece of common prior knowledge for typical traffic type; The BS, as a transmitter or receiver, can have multiple pieces of common prior knowledge related to multiple spatial environments or sub-environments: - Alternative #1: First piece of common prior knowledge for a first spatial environment; second piece of common prior knowledge for a second spatial sub-environment; the first spatial environment and the second spatial environment can be overlapping; or the first spatial environment and the second spatial environment can be non-overlapping; - Alternative #2: First piece of common prior knowledge for a spatial environment; second piece of common prior knowledge for a first spatial sub-environment; third piece of common prior knowledge for a second spatial sub-environment; the first spatial sub-environment and the second spatial sub-environment belong to the spatial environment; the first spatial sub-environment and the second spatial sub-environment can be overlapping; or the first spatial sub-environment and the second spatial sub-environment can be non-overlapping; In general, the above alternatives can be flexibly combined in practice. represents prior knowledge that varies depending on factors such as weather, environment, traffic, etc. The BS can select a piece of prior knowledge .

[0388] Example 2: Representing multiple pieces of prior knowledge Prior knowledge in Example 1 is a conceptual entity, which can be embodied as - Channel space bases ; - Pilot placement matrix and its compact channel space bases (or ); - Set of reference channels , scoring function and common threshold

[0389] In addition, according to Example 11 of the invention [8], the BS can have a pairing graph related to the prior knowledge . In summary, given the prior knowledge , the BS can store the pilot placement scheme, compact channel space bases, set of reference channels, scoring function, common threshold and the number of pairing graphs on each RBG. The BS can have multiple pieces of prior knowledge, each with a pilot placement scheme, compact channel space bases, set of spatial reference channels, scoring function, common threshold and the number of pairing graphs on each RBG.

[0390] To avoid the conceptual entity on the prior knowledge, we represent an entity , which includes: - Pilot placement matrix and its compact channel space bases (or ); - Set of reference channels , scoring function and common threshold

[0391] Determined or selected by multiple selection factors:

[0392] Figure 36 is the flowchart of Example 2.

[0393] Example 3: Updating the set of spatial reference channels Updating a set in broadcast or groupcast fashion A base station has multiple . and Two sets share the same environment. In the following case, the BS adapts its associated UE from to : - Case #1: The BS changes its frequency band; for example, from 10 GHz to 12 GHz; - Case #2: BS changes its RBG; for example, from 1 RBG = 4 RB to 1 RBG = 16 RG; - Situation #3: It has started snowing; -Scenario #4: The peak traffic period has passed, and there are far fewer users; -etc.

[0394] The updated set is described in embodiment 9 of the invention [8].

[0395] Updating one set for one or several UEs and The two sets share the same environment. Besides... and In addition, and They are almost identical. Different pilot arrangement matrices will produce different compact channel space bases. and .expected Locations include Location: and corresponding This can be understood as the BS increasing the pilot density of one or more UEs. Therefore, only the changes in the multicast or unicast DL channels are updated. and .

[0396] and The two sets relate to different environments. If the BS estimates or predicts that a UE or a group of UEs is moving from a first environment to a second environment, the BS will notify the UE via broadcast, multicast, or unicast DL channels. Updated to .

[0397] Updating several sets for one or several UEs and The two sets are associated with different environments, with the second environment being a sub-environment of the first. The BS can update the sets to the UE simultaneously. and . This is the default one. The UE will provide feedback in the first cycle. The UE will then indicate its nearest reference channel. Preferably, alternatively, the UE will continue to provide feedback during the second cycle. The indication of its nearest reference channel. For example, With some pre-installed precoders (beamforming).

[0398] And Two sets are associated with different environments, the second environment partially overlaps with the first environment. The BS can update the sets And to the UE simultaneously. , The UE decides to feedback the indication of the nearest reference channel in

[0399] The BS updates the UE from to through broadcast, groupcast or unicast DL channel.

[0400] Figures 37 to 41 is the flowchart of embodiment 3.

[0401] Updating a partial set for one or several UEs It is expensive to send the entire to the UE in broadcast or groupcast DL channel. If the BS knows the approximate location of a UE or a group of UEs, it can send the part of closer to the UE or the group of UEs to the UE or the group of UEs.

[0402] [1] PCT / CN2022 / 126878 Channel estimation method and device for MIMO system [2] PCT / CN2022 / 094688 Method for designing transmission dimension and reference signal arrangement scheme of transmission channel according to prior structure dimension [3] Column rotation QRD: https: / / en.wikipedia.org / wiki / QR_decomposition [4] SVD: https: / / en.wikipedia.org / wiki / QR_decomposition [5] Pseudo-inverse: https: / / en.wikipedia.org / wiki / Moore%E2%80%93Penrose_inverse [6] MSE: https: / / en.wikipedia.org / wiki / Mean_squared_error [7] Condition number of matrix: https: / / en.wikipedia.org / wiki / Condition_number 6G system structure 6G basic module structure According to Figure 42 , one or more steps in the embodiment method provided herein can be performed by the corresponding unit or module. Figure 42Units or modules in the device are shown, for example, in the ED 110, in the T-TRP 170, or in the NT-TRP 172. For example, a signal can be transmitted by a transmitting unit or a transmitting module. For example, a signal can be transmitted by a transmitting unit or a transmitting module. A signal can be received by a receiving unit or a receiving module. A signal can be processed by a processing unit or a processing module. Other steps can be performed by an artificial intelligence (AI) module or a machine learning (ML) module. The corresponding units or modules can be implemented using hardware, one or more components or devices executing software, or a combination thereof. For example, one or more of these units or modules can be an integrated circuit, such as a programmed FPGA, GPU, ASIC. It should be understood that if these modules are implemented by a processor using software for execution, these modules can be retrieved by the processor as a whole or in part, individually or collectively, for processing, in one or more instances, and these modules themselves can include instructions for further deployment and instantiation, as needed.

[0403] Other details about the ED 110, the T-TRP 170, and the NT-TRP 172 are known to those skilled in the art. Therefore, these details are omitted here.

[0404] A non-exhaustive list of possible units or possible configurable parameters or MIMO systems in some embodiments includes: Panel: The unit of an antenna group or an antenna array or an antenna subarray can independently control its Tx or Rx beam.

[0405] Beam: A beam is formed by performing amplitude and / or phase weighting on data transmitted or received by at least one antenna port, and other methods can also be used, for example, by adjusting related parameters of an antenna unit. A beam can include a Tx beam and / or an Rx beam. A transmit beam indicates the distribution of signal strength in different directions in space after a signal transmitted by an antenna. A receive beam indicates the distribution of signal strength in different directions in space of a wireless signal received from an antenna. Beam information can be a beam identifier, or an antenna port identifier, or a CSI-RS resource identifier, or an SSB resource identifier, or an SRS resource identifier, or an identifier of other reference signals.

[0406] 1 One column of is a basis, which means that Any two columns of are orthogonal to each other. In IPR, we take columns as a basis; this can be easily applied to a basis matrix with rows as a basis, simply denoted as .

Claims

1. A communication method characterized by comprising: comprising: sending, to a user equipment, first information indicating a first set of reference channels related to a first set of environmental parameters; sending, to the user equipment, second information related to the first set of environmental parameters, the second information being used to determine one or more reference channels from the first set of reference channels.

2. The communication method according to claim 1, characterized by, the second information indicates one or more of a first pilot pattern, a first compression function, a first scoring function, and a first threshold value; the first compression function is used to determine one or more of: the one or more reference channels in the first set of reference channels, a channel measurement of a first downlink (DL) channel of the user equipment; the first scoring function is used to determine a distance between the first DL channel and a reference channel in the first set of reference channels; the first threshold value is used to determine the one or more reference channels in the first set of reference channels.

3. The communication method according to claim 1 or 2, characterized by, the method further comprising: sending, to the user equipment, third information related to a second set of environmental parameters, the third information indicating one or more of a second pilot pattern and a second compression function; the second compression function is used to determine one or more of: one or more reference channels in a set of reference channels, a channel measurement of a second DL channel of the user equipment.

4. The communication method according to claim 3, characterized by, the second set of environmental parameters comprises the first set of environmental parameters; the second pilot pattern indicates a portion of a pilot pattern related to the first set of environmental parameters and a pilot pattern related to the second set of environmental parameters that has changed; the second compression function indicates a portion of a compression function related to the first set of environmental parameters and a compression function related to the second set of environmental parameters that has changed.

5. The communication method according to claim 3 or 4, characterized by, the sending, to the user equipment, third information related to a second set of environmental parameters comprises: sending the third information to the user equipment when determining a change from a first channel condition to a second channel condition, wherein the first channel condition is related to the first set of environmental parameters and the second channel condition is related to the second set of environmental parameters; sending the third information to the user equipment when determining that a current channel condition comprises the first channel condition and the second channel condition; or sending the third information to the user equipment when estimating or predicting a change in channel condition of the user equipment from the first channel condition to the second channel condition.

6. The communication method according to any one of claims 3 to 5, characterized by, the method further comprising: sending, to the user equipment, fourth information indicating a second set of reference channels related to the second set of environmental parameters.

7. The communication method according to claim 6, wherein, the third information further indicates one or more of a second scoring function or a second threshold value; wherein the second scoring function is used to determine a distance between a DL channel of the user equipment and a reference channel in the second set of reference channels; and the second threshold value is used to determine one or more reference channels in the second set of reference channels.

8. The communication method according to any one of claims 1 to 7, characterized by, the method further comprising: receiving, from the user equipment, fifth information indicating a first reference channel, wherein a distance between the first reference channel and a DL channel of the user equipment is less than or equal to a third threshold, and wherein the one or more reference channels of the first set of reference channels comprise the first reference channel.

9. The communication method according to claim 6 or 7, characterized by, The method further comprises: receiving, from the user equipment, sixth information indicating a second reference channel of the second set of reference channels, wherein a distance between the second reference channel and a DL channel of the user equipment is less than or equal to a fourth threshold.

10. The communication method according to claim 9, wherein, The distance between the second reference channel and the DL channel is less than a distance between any reference channel of the first set of reference channels and the DL channel.

11. The communication method according to claim 9, wherein The method further comprises: receiving, from the user equipment, seventh information indicating a first distance between a reference channel of the first set of reference channels and the DL channel and eighth information indicating a second distance between the second reference channel and the DL channel; wherein the first distance and the second distance are used to determine a set of environmental parameters for user equipment pairing from the first set of environmental parameters and the second set of environmental parameters.

12. The communication method according to any one of claims 1 to 11, characterized by, The first set of reference channels is determined according to a location of the user equipment or channel conditions related to the user equipment. 13.A communication method applied to a user equipment, comprising: comprises: receiving, from a central device, first information indicating a first set of reference channels related to a first set of environmental parameters; receiving, from the central device, second information related to the first set of environmental parameters, the second information being used to determine one or more reference channels from the first set of reference channels.

14. The communication method according to claim 13, wherein, The second information indicates one or more of a first pilot pattern, a first compression function, a first scoring function, and a first threshold value; The first compression function is used to determine one or more of: the one or more reference channels of the first set of reference channels, a channel measurement of a first downlink (DL) channel of the user equipment; The first scoring function is used to determine a distance between the first DL channel and one reference channel of the first set of reference channels; The first threshold value is used to determine the one or more reference channels of the first set of reference channels.

15. The communication method according to claim 13 or 14, characterized by, The method further comprises: receiving, from the central device, third information related to a second set of environmental parameters, the third information indicating one or more of a second pilot pattern and a second compression function; The second compression function is used to determine one or more of: one or more reference channels of a set of reference channels, a channel measurement of a second DL channel of the user equipment.

16. The communication method according to claim 15, wherein, The second set of environmental parameters comprises the first set of environmental parameters; the second pilot pattern indicates a portion of a pilot pattern related to the first set of environmental parameters and a pilot pattern related to the second set of environmental parameters that has changed; and the second compression function indicates a portion of a compression function related to the first set of environmental parameters and a compression function related to the second set of environmental parameters that has changed.

17. The communication method according to claim 15 or 16, wherein, The method further comprises: receiving, from the central device, fourth information indicating a second set of reference channels related to the second set of environmental parameters.

18. The communication method according to claim 17, wherein, The third information further indicates one or more of a second score function or a second threshold value; The second score function is used to determine a distance between a DL channel of the user equipment and one reference channel in the second set of reference channels; and the second threshold value is used to determine one or more reference channels in the second set of reference channels.

19. The communication method according to any one of claims 13 to 18, characterized by, The method further comprises: sending, to the central device, fifth information indicating a first reference channel, wherein a distance between the first reference channel and a DL channel of the user equipment is less than or equal to a third threshold value, and the one or more reference channels in the first set of reference channels include the first reference channel.

20. The communication method according to claim 17 or 18, wherein, The method further comprises: sending, to the central device, sixth information indicating a second reference channel in the second set of reference channels, wherein a distance between the second reference channel and a DL channel of the user equipment is less than or equal to a fourth threshold value.

21. The communication method according to claim 20, wherein, The distance between the second reference channel and the DL channel is less than a distance between any reference channel in the first set of reference channels and the DL channel.

22. The communication method of claim 20, wherein, The method further comprises: sending, to the central device, seventh information indicating a first distance between a reference channel in the first set of reference channels and the DL channel and eighth information indicating a second distance between the second reference channel and the DL channel; The first distance and the second distance are used to determine, from the first set of environmental parameters and the second set of environmental parameters, a set of environmental parameters for user equipment pairing.

23. The communication method according to any one of claims 13 to 22, characterized by, The first set of reference channels is determined according to a location of the user equipment or a channel condition related to the user equipment. 24.A communication method applied to a user equipment, comprising: Comprise: receiving, from a central device, first information indicating a first set of reference channels related to a first set of environmental parameters; determining whether there is a first reference channel in the first set of reference channels having a distance less than or equal to a first threshold value from a downlink (DL) channel of the user equipment.

25. The communication method according to claim 24, wherein, The method further comprises: receiving, from the central device, fourth information indicating a second set of reference channels related to a second set of environmental parameters; determining whether there is a second reference channel in the second set of reference channels having a distance less than or equal to a second threshold value from the DL channel of the user equipment.

26. The communication method of claim 25, wherein, The first reference channel in the first set of reference channels has a distance less than or equal to the first threshold value from the DL channel, and none of the reference channels in the second set of reference channels has a distance less than or equal to the second threshold value from the DL channel; the method further comprises: sending, to the central device, fifth information indicating the first reference channel.

27. The communication method of claim 25, wherein, The second reference channel in the second set of reference channels has a distance less than or equal to the second threshold value from the DL channel, and none of the reference channels in the first set of reference channels has a distance less than or equal to the first threshold value from the DL channel; the method further comprises: sending, to the central device, sixth information indicating the second reference channel. The second reference channel in the second set of reference channels has a distance less than or equal to the second threshold value from the DL channel, and none of the reference channels in the first set of reference channels has a distance less than or equal to the first threshold value from the DL channel; the method further comprises: sending, to the central device, sixth information indicating the second reference channel.

28. The communication method of claim 25, wherein, The first reference channel in the first group of reference channels is less than or equal to the first threshold value from the DL channel, and the second reference channel in the second group of reference channels is less than or equal to the second threshold value from the DL channel; the method further comprises: sending, to the central device, ninth information indicating a reference channel closer to the DL channel from among the first reference channel and the second reference channel.

29. The communication method of claim 25, wherein, The first reference channel in the first group of reference channels is less than or equal to the first threshold value from the DL channel, and the second reference channel in the second group of reference channels is less than or equal to the second threshold value from the DL channel; the method further comprises: sending, to the central device, tenth information indicating the first reference channel and the second reference channel.

30. The communication method of claim 29, wherein, The method further comprises: sending, to the central device, eleventh information indicating the first distance and the second distance.

31. A communications device, characterized by The apparatus comprises a processor and a memory, the memory storing instructions executable on the processor, which when executed cause the apparatus to perform the method according to any one of claims 1 to 12.

32. A communications device, characterized by The apparatus comprises a processor and a memory, the memory storing instructions executable on the processor, which when executed cause the apparatus to perform the method according to any one of claims 13 to 23 or perform the method according to any one of claims 24 to 30.

33. A communications device, characterized by The apparatus comprises functions or units for performing the method according to any one of claims 1 to 12.

34. A communications device, characterized by The apparatus comprises functions or units for performing the method according to any one of claims 13 to 23 or performing the method according to any one of claims 24 to 30.

35. A computer-readable storage medium, comprising: comprise instructions which, when executed on a computer, cause the computer to perform any one of the following methods: the method according to any one of claims 1 to 12, the method according to any one of claims 13 to 23, or the method according to any one of claims 24 to 30.

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