Communication method, device, and storage medium

Abstract

A communication method, an apparatus, and a storage medium relating to the field of communication technologies are provided. The method may be performed by a network device. The method includes the steps of: determining first downlink transmission parameters of a first terminal device based on a state of a downlink channel of the first terminal device, the first downlink transmission parameters including a first rank; determining a first number of RBs occupied by downlink data of the first terminal device based on the first downlink transmission parameters; determining a first number of remaining RBs based on the number of allocatable RBs and the first number of RBs; and, if the first terminal device satisfies at least a first condition, performing downlink data transmission with the first terminal device based on second downlink transmission parameters, the second downlink transmission parameters including a second rank, the number of spatial multiplexing streams indicated by the second rank being less than the number of spatial multiplexing streams indicated by the first rank, and the first condition including that the first remaining number of RBs supports a reduction of the first terminal device's rank from the first to the second rank.

Description

[Technical Field]

[0001] [Related Applications] This application claims priority to Chinese Patent Application No. 202211478466.3, filed with the State Intellectual Property Office of China on November 23, 2022, entitled "COMMUNICATION METHOD AND APPARATUS, AND STORAGE MEDIUM," which is incorporated herein by reference in its entirety.

[0002] [Technical field] The present application relates to the field of wireless communication technology, and in particular to a communication method and device and a storage medium. [Background technology]

[0003] With the evolution of antenna technology used in wireless communication systems from single-input single-output (SISO) to massive multiple-input multiple-output (MIMO), and with the evolution of systems from 3G to 5th generation mobile communication technology (5G) new radio (NR), the maximum number of spatially multiplexed streams that a single terminal device can support in downlink transmission increases from one to four. The number of spatially multiplexed streams is also called the rank value. Theoretically, a higher rank indicates higher system throughput performance. However, in a contiguous coverage area, a higher user rank indicates higher inter-cell interference on the physical downlink shared channel (PDSCH) and the demodulation reference signal (DMRS) of other users.

[0004] For example, Figure 1 shows horizontal cross-sections of a user's first and third stream beams when Rank 3 is used for downlink transmission (i.e., three streams are used for spatial multiplexing). The 0-degree direction is the direction in which the antenna faces the cell, and the larger the beam deflection angle, the greater the deflection toward adjacent cells. The horizontal spread angle of the user's third stream beam is larger than that of the first stream beam. In other words, the horizontal angle direction of the third stream beam is clearly deflected toward adjacent cells, causing strong interference to the adjacent cells.

[0005] Therefore, how to reduce interference with other users when ensuring the transmission of user data is a technical problem that needs to be solved at present. Summary of the Invention

[0006] The embodiments of the present application provide a communication method, device, and storage medium that reduce interference by reducing the rank (i.e., the number of spatial multiplexing streams) for downlink transmission by a terminal device.

[0007] According to a first aspect, a communication method is provided. The method may be applied to a network device, for example, a base station. The method includes the steps of: determining first downlink transmission parameters of a first terminal device based on a state of a downlink channel of the first terminal device, the first downlink transmission parameters including a first rank; determining a first number of resource blocks (RBs) occupied by downlink data of the first terminal device based on the first downlink transmission parameters; determining a first number of remaining RBs based on the number of allocatable RBs and the first number of RBs; and, if the first terminal device satisfies at least a first condition, performing downlink data transmission with the first terminal device based on second downlink transmission parameters, the second downlink transmission parameters including a second rank, the number of spatial multiplexing streams indicated by the second rank being less than the number of spatial multiplexing streams indicated by the first rank, and the first condition including that the first remaining number of RBs supports a reduction from the first rank to the second rank of the first terminal device.

[0008] Optionally, the first remaining number of RBs supporting a reduction from the first rank to the second rank of the first terminal device includes the first remaining number of RBs being equal to or greater than the difference between the second number of RBs and the first number of RBs, where the second number of RBs is the number of RBs occupied by downlink data of the first terminal device, determined based on second downlink transmission parameters, and the second number of RBs is greater than the first number of RBs.

[0009] In the above embodiment, when scheduling downlink transmission for the first terminal device, the network device considers the channel state and further considers the RB utilization rate and downlink traffic volume (i.e., the amount of downlink data) of the first terminal device, and ensures the downlink data transmission of the terminal device by reducing the rank to reduce the interference level and the number of interference sources, thereby improving the interference suppression effect of the demodulation of the terminal device in the adjacent cell.

[0010] In a possible embodiment, the first terminal device is one of at least two terminal devices based on single-user scheduling, and the at least two terminal devices further include a second terminal device, and the number of spatial multiplexing streams determined based on the state of the downlink channels of the first terminal device and the second terminal device is greater than 1, the first remaining number of RBs of the first terminal device supports a reduction from the first rank to the second rank for the first terminal device, and the second remaining number of RBs of the second terminal device supports a reduction from the third rank to the fourth rank for the second terminal device, but when the reduction from the first rank to the second rank is performed for the first terminal device, the first remaining number of RBs does not support a reduction from the third rank to the fourth rank for the second terminal device. The second remaining number of RBs is determined based on the number of allocatable RBs and the number of RBs occupied by downlink data of the second terminal device, and the third rank is determined based on the state of the downlink channel of the second terminal device. In the above case, the remaining RB number indicates that a reduction in the rank of the first terminal device is supported, and that a reduction in the rank of the second terminal device is also supported, but a simultaneous reduction in the ranks of the first terminal device and the second terminal device is not supported. In this case, performing downlink data transmission with the first terminal device based on the second downlink transmission parameter when the first terminal device at least satisfies the first condition includes selecting the first terminal device from the first terminal device and the second terminal device, and performing downlink data transmission with the first terminal device based on the second downlink transmission parameter. In this embodiment, in order to reduce interference, some terminal devices may be selected for rank reduction processing in the above case.

[0011] In a possible embodiment, selecting the first terminal device from the first terminal device and the second terminal device includes selecting the first terminal device from the first terminal device and the second terminal device if the first terminal device further satisfies a second condition, the second condition including that the strength of interference of the first terminal device to a neighboring cell is greater than the strength of interference of the second terminal device to a neighboring cell.

[0012] In the above implementation, terminal devices that cause large interference to neighboring cells are preferentially selected to reduce the rank of the terminal devices, thereby reducing interference to neighboring cells.

[0013] In a possible implementation, the first terminal device is a terminal device in a first multi-user group of at least two multi-user groups based on multi-user scheduling, the at least two multi-user groups further including a second multi-user group, the number of allocatable RBs is the total number of RBs occupied by downlink data of the terminal devices in the second multi-user group, and the total number of RBs occupied by downlink data of the terminal devices in the second multi-user group is greater than or equal to the total number of RBs occupied by downlink data of the terminal devices in each of the at least two multi-user groups.

[0014] In the above implementation, the number of RBs occupied by the downlink data of the terminal devices in each multi-user (MU) group may be limited to avoid the problem of the number of RBs occupied by the downlink data of the terminal devices increasing excessively after the rank of the terminal devices in the MU group is reduced.

[0015] In a possible implementation, the first multi-user group further includes a second terminal device, and the numbers of both spatial multiplexing streams determined based on the state of the downlink channels of the first terminal device and the second terminal device are greater than 1. The first remaining number of RBs of the first terminal device supports a reduction from the first rank to the second rank for the first terminal device, and the second remaining number of RBs of the second terminal device supports a reduction from the third rank to the fourth rank for the second terminal device, but when the reduction from the first rank to the second rank is performed for the first terminal device, the first remaining number of RBs does not support a reduction from the third rank to the fourth rank for the second terminal device. The second remaining number of RBs of the second terminal device is determined based on the number of allocatable RBs and the number of RBs occupied by the downlink data of the second terminal device, and the third rank is determined based on the state of the downlink channel of the second terminal device. In the above case, it is indicated that the number of remaining RBs in one multi-user group supports a reduction in the rank of the first terminal device and also supports a reduction in the rank of the second terminal device, but does not support a simultaneous reduction in the ranks of the first terminal device and the second terminal device. In this case, performing downlink data transmission with the first terminal device based on the second downlink transmission parameter when the first terminal device at least satisfies the first condition includes selecting the first terminal device from the first terminal device and the second terminal device, and performing downlink data transmission with the first terminal device based on the second downlink transmission parameter. In this embodiment, in order to reduce interference, some terminal devices may be selected for rank reduction processing in the above case.

[0016] In a possible embodiment, selecting the first terminal device from the first terminal device and the second terminal device includes selecting the first terminal device from the first terminal device and the second terminal device if the first terminal device further satisfies a third condition. The third condition may be that the scheduling priority of the first terminal device is higher than the scheduling priority of the second terminal device. In this case, the rank reduction process is performed preferentially on the terminal device with the higher scheduling priority. Alternatively, the third condition may be that the strength of interference of the first terminal device with a neighboring cell is greater than the strength of interference of the second terminal device with a neighboring cell. In this case, the terminal device with the greater strength of interference with the neighboring cell may be preferentially selected for the rank reduction process.

[0017] In a possible implementation, the step of selecting the first terminal device from the first terminal device and the second terminal device includes: determining a corresponding first transmission power reduction amount based on a first MCS of the first terminal device, and determining a corresponding second transmission power reduction amount based on the first MCS of the second terminal device; selecting a first terminal device from a first terminal device and a second terminal device when the first transmission power reduction amount is greater than the second transmission power reduction amount; Before performing downlink data transmission with the first terminal device based on the second downlink transmission parameters, the method further includes reducing the transmission power of the first terminal device based on the first transmission power reduction amount.

[0018] In such an implementation, terminal devices with larger power reduction amounts can be preferentially selected for rank reduction processing to reduce interference and further save energy.

[0019] In a possible implementation, before transmitting downlink data with the first terminal device based on the second downlink transmission parameters, the method further includes a step of reducing the transmission power of the first terminal device, thereby enabling further energy savings based on reducing interference.

[0020] In a possible implementation, the first downlink transmission parameters further include a first modulation and coding scheme (MCS), and the second downlink transmission parameters further include a second MCS, where the first MCS is equal to the second MCS.

[0021] According to a second aspect, there is provided a communication device. The communication device may be a network device (e.g., a base station) or may be a communication device used in the network device (e.g., a base station). The communication device may include a processing unit and a transceiver unit. The processing unit is configured to: determine first downlink transmission parameters for a first terminal device based on a state of a downlink channel of the first terminal device, the first downlink transmission parameters including a first rank; determine a first number of resource blocks (RBs) occupied by downlink data of the first terminal device based on the first downlink transmission parameters; determine a first number of remaining RBs based on a number of allocatable RBs and the first number of RBs; and, if the first terminal device satisfies at least a first condition, perform downlink data transmission with the first terminal device based on second downlink transmission parameters, the transceiver unit, the second downlink transmission parameters including a second rank, the number of spatial multiplexing streams indicated by the second rank being less than the number of spatial multiplexing streams indicated by the first rank, and the first condition including the first remaining number of RBs supporting a reduction from the first rank to the second rank of the first terminal device.

[0022] According to a third aspect, there is provided a communications device including one or more processors, the one or more processors enabling the communications device to perform a method according to any one of the implementations of the first aspect when instructions of one or more computer programs are executed by the one or more processors.

[0023] According to a fourth aspect, there is provided a computer-readable storage medium comprising a computer program that, when executed on a computing device, enables the computing device to perform a method according to any one of the implementations of the first aspect.

[0024] According to a fifth aspect, there is provided a chip coupled to a memory and configured to read and execute program instructions stored in the memory to perform a method according to any one of the implementations of the first aspect.

[0025] According to a sixth aspect, there is provided a computer program product, which, when executed by a computer, enables the computer to carry out a method according to any one of the implementations of the first aspect.

[0026] For the beneficial effects of the second to sixth aspects, please refer to the beneficial effects of the first aspect, and the details will not be described again here. [Brief explanation of the drawings]

[0027] [Figure 1] This is a diagram of the horizontal beam directions of the first and third streams of a user in the Rank3 scenario.

[0028] [Figure 2] This is a resource distribution diagram of DMRS port0 / 1 and DMR port2 / 3.

[0029] [Figure 3] 10 is a diagram of simulation results comparing performance loss with DMRS RM enabled and disabled under different ranks of interference;

[0030] [Figure 4] A comparison of IRC performance when there are multiple interference sources.

[0031] [Figure 5] FIG. 10 is a frequency selective fading diagram for a group with heavy traffic.

[0032] [Figure 6] FIG. 1 is a diagram of a network architecture to which an embodiment of the present application is applied.

[0033] [Figure 7] 1 is a schematic flowchart of a communication method according to an embodiment of the present application;

[0034] [Figure 8] FIG. 1 illustrates reducing interference by decreasing the rank of a UE in a single-user scheduling scenario according to an embodiment of the present application.

[0035] [Figure 9] FIG. 1 illustrates a diagram of selecting UEs for rank reduction based on interference identification in a SU scheduling scenario according to an embodiment of the present application.

[0036] [Figure 10] FIG. 10 illustrates a diagram of decreasing rank in a MU scheduling scenario according to an embodiment of the present application.

[0037] [Figure 11] 1 is a diagram of a communication device according to an embodiment of the present application; [Figure 12] 1 is a diagram of a communication device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0038] To clarify the objectives, technical solutions and advantages of the embodiments of the present application, the following describes the embodiments of the present application in detail with reference to the accompanying drawings.

[0039] It should be understood that in this application, "at least one" means one or more, and "multiple" means two or more. The term "and / or" describes an association relationship between associated objects and indicates that three relationships may exist. For example, A and / or B may represent the following cases: only A is present, A and both are present, and only B is present, where A and B may be singular or plural. In the text of this application, the character " / " typically indicates an "or" relationship between associated objects. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of a single item or multiple items. For example, at least one item of a, b, and c may refer to a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c may each be singular or plural. The terms "first," "second," etc. are intended to distinguish between similar objects and do not necessarily describe a particular order or sequence. Furthermore, the terms "comprise," "have," and any variations thereof are intended to cover a non-exclusive inclusion, for example, including a series of steps or units. For example, a method, system, product, or apparatus is not necessarily limited to those steps or units expressly listed, but may include other steps or units not expressly listed or inherent to such process, method, product, or apparatus.

[0040] First, the related art in the embodiments of the present application will be described below.

[0041] (1) Rank

[0042] The rank is the rank of the transmission channel and can be thought of as the number of independent parallel channels between the transmitter and receiver, indicating the number of relatively independent data paths that can be supported simultaneously. In practical products, the rank value is generally thought of as the number of spatially multiplexed streams.

[0043] In wireless communication systems, multi-antenna transmission and spatial multiplexing techniques can be used to transmit multiple layers of data streams in parallel over the same time-frequency resource. Rank simply refers to the same time-frequency resource, divided into several parts for simultaneous transmission in space. Codewords are mapped to streams through layer mapping (number of codewords ≤ number of streams ≤ number of antenna ports). When the time-frequency resource remains constant, a higher rank indicates a higher actual throughput.

[0044] The rank may be determined based on the channel conditions: generally, better channel conditions result in a higher rank value.

[0045] In this specification, Rank1 indicates that the rank value is 1 (or the number of spatial multiplexing streams is 1), and Rank2 indicates that the rank value is 2 (or the number of spatial multiplexing streams is 2).

[0046] In this specification, the "first rank" can be understood as the first number of spatial multiplexing streams. For example, the first rank may be Rank 4. The "second rank" can be understood as the second number of spatial multiplexing streams. For example, the second rank may be Rank 2.

[0047] (2) Single-user (SU) scheduling

[0048] SU scheduling means that one time-frequency resource can be used by only one user, or that one time-frequency resource can be allocated to only one terminal device (user equipment, UE).

[0049] (3) Multi-user (MU) scheduling

[0050] MU scheduling means that multiple users can share time-frequency resources, or one time-frequency resource can be allocated to multiple UEs. Multi-user scheduling can use MIMO technology.

[0051] In MIMO technology, the transmitting end and the receiving end each use multiple transmitting antennas and multiple receiving antennas to transmit and receive signals through the multiple antennas of the transmitting end and the receiving end, and form multiple channels between the transmitting end and the receiving end to improve communication quality and increase channel capacity. The essence of MIMO technology is to provide the system with spatial diversity gain and spatial multiplexing gain.

[0052] When using MU scheduling, two or more UEs can be paired. This is called an MU pairing combination or MU pairing. One MU pairing combination can include multiple UEs, and the UEs can share one resource block (RB) resource through spatial multiplexing. In other words, multiple UEs simultaneously perform spatial multiplexing on one RB resource.

[0053] Furthermore, when MU scheduling is used, UEs can be grouped into different groups based on beam separation and correlation. The different groups are called MU groups. UEs in the same MU group use different frequency domain resources, and UEs in different MU groups use different spatial domain resources after pairing.

[0054] (4) DMRS Data Pilot Shared Symbol (DMRS Rate Matching, DMRS RM) Technology

[0055] For a scheduled UE, the DMRS signal occupies only some resource elements (REs) on the symbol used for transmitting the DMRS signal. In this case, the REs not occupied by the DMRS signal can be used to transmit downlink data. That is, the DMRS signal and downlink data can be transmitted in one symbol. This is called DMRS RM.

[0056] (5) Modulation and coding scheme (MCS)

[0057] The MCS determines the modulation scheme and code rate for the user. Different MCSs correspond to different modulation schemes and code rates. The base station uses the MCS to ensure the transmission efficiency and transmission quality of the UE service. When the channel quality is good, a higher-order modulation scheme and higher coding efficiency are used (fewer protection bits are added). When the channel quality is poor, a lower-order modulation scheme and lower coding efficiency are used (more protection bits are added). The amount of data that has effective bits and can be transmitted in one RB is determined based on the MCS. The higher the MCS, the more effective data can be transmitted in one RB, and the higher the requirements for channel quality.

[0058] Currently, for downlink data transmission, PDSCH scheduling is mainly performed in an optimal single-user performance manner, which includes the following steps:

[0059] Step 1: Allocate DMRS pilots.

[0060] The DMRS is a demodulation reference signal and needs to be distinguished between different UEs and different layers of the same UE (in other words, different spatially multiplexed streams). One DMRS port (DMRS Port) needs to be assigned to each stream. For example, if downlink transmission with the UE is performed based on Rank 1, only DMRS Port 0 or DMRS Port 1 needs to be occupied. For example, if downlink transmission with the UE is performed based on Rank 2, DMRS Port 0 and DMRS Port 1 need to be occupied. If downlink transmission with the UE is performed based on Rank 3, not only DMRS Port 0 and DMRS Port 1 need to be occupied, but also DMRS Port 2 or DMRS Port 3 need to be occupied. If downlink transmission with the UE is performed based on Rank 4, DMRS Port 0, DMRS Port 1, DMRS Port 2, and DMRS Port 3 need to be occupied.

[0061] Figure 2 shows the distribution of DMRS port0 / 1 and DMRS port2 / 3. When using the DMRS RM technique, if the resources corresponding to the DMRS ports are not fully occupied, the DMRS signal and PDSCH may share symbols. For example, when downlink transmission with a UE is performed based on Rank 2, the DMRS signal occupies the time-frequency resources corresponding to DMRS port0 and DMRS port1. In this case, the REs of DMRS port2 and / or the REs of DMRS port3 may be used for PDSCH transmission.

[0062] Step 2: Suppress PDSCH interference in neighboring cells.

[0063] For UEs in the primary cell, a higher rank of the interfering UE indicates a larger number of interference sources. If the UE in the primary cell uses interference rejection combining (IRC) technology, it can suppress co-channel interference using the spatially colored characteristics of the interfering signal, thereby obtaining additional interference suppression gain and improving system performance.

[0064] Step 3: Perform MU pairing combinations within the cell.

[0065] This indicates that the higher the rank of the UE in the MU pairing combination, the greater the total amount of spatial multiplexing layers for pairing, and the greater the interference between MU groups.

[0066] Currently, the rank selection of a UE is mainly determined by the channel condition of the UE. If the channel condition of the UE is good, a high rank is preferred for downlink data transmission. Using a high rank for downlink data transmission also increases interference. This can be reflected in several aspects, specifically as follows:

[0067] (1) The higher the rank, the greater the interference to adjacent cells. For example, when downlink data is transmitted based on Rank 3, the spatial dispersion of the third stream beam becomes large, and the horizontal beam direction is deflected toward adjacent cells, causing significant interference to signals on the same frequency resource in adjacent cells.

[0068] (2) Also, if DMRS RM is enabled for a UE in the primary cell but not for a neighboring cell, the UE in the neighboring cell will transmit downlink data based on a higher rank, causing the UE in the primary cell to inaccurately estimate interference.

[0069] FIG. 3 is a diagram of simulation results comparing performance loss when DMRS RM is enabled and disabled under different ranks of interference. Case 1 represents a scenario in which DMRS RM is not enabled in both the primary cell and the neighboring cell. Case 2 represents a scenario in which DMRS RM is enabled in the primary cell but not in the neighboring cell. Curve 301 represents the loss of total user capacity of the local cell in Case 2 compared to Case 1 when the neighboring cell uses Rank 2. Curve 302 represents the loss of total user capacity of the local cell in Case 2 compared to Case 1 when the UE in the neighboring cell uses Rank 4. It can be seen that when the UE in the neighboring cell uses Rank 4, the performance loss of the UE in the local cell when DMRS RM is enabled is greater than the performance loss of the UE in the local cell when DMRS RM is not enabled. The performance loss can reach up to 30% (not considering the resource gain of RE). Simulation results show that in Case 2, when a UE in the primary cell transmits downlink data based on a low rank (e.g., Rank 1 or Rank 2), and the DMRS signal and PDSCH share symbols, and a UE in a neighboring cell transmits downlink data based on a high rank (e.g., Rank 3 or Rank 4), i.e., when the DMRS port of the neighboring cell is fully occupied, the total capacity loss of the primary cell becomes large. That is, when a UE in the neighboring cell transmits downlink data at Rank 4, the UE in the primary cell may inaccurately estimate the interference to the neighboring cell, and some transmission parameters (e.g., MCS) may not be selected appropriately. This affects the data transmission performance of the UE in the primary cell.

[0070] (3) Furthermore, when using IRC technology, the greater the number of interference sources, the greater the impact on the performance of the receiver using IRC technology, given the same interference strength. Figure 4 compares IRC performance when there are multiple interference sources. The scenario for the simulation results shown in Figure 4 is non-line-of-sight (NLOS) transmission. The UE bandwidth is 12 RBs, the UE uses four receive antennas, and the downlink transmission parameter MCS is 16 (MCS=16). In this scenario, curves 1 to 4 show the change curves of the UE receiver's interference suppression gain due to thermal interference (IoT) under one to four interference sources, respectively. It can be seen that the greater the number of interference sources, the smaller the interference suppression gain obtained by the UE.

[0071] (4) In addition, in MU scheduling, the higher the rank of the UE in each MU group, the greater the interference between the MU groups. Furthermore, when there is an MU group with low traffic volume, frequency-selective fading occurs for the MU group with high traffic volume. As shown in Figure 5, UE0, UE1, and UE2 are terminal devices in different MU groups, and UE0, UE1, and UE2 are terminal devices with the same MU pairing combination. UE0's frequency domain resources partially overlap with those of UE1 and UE2. Therefore, UE0, UE1, and UE2 perform spatial multiplexing. When interference exists between MU groups, UE0's attenuation increases on the overlapping frequency domain resources and decreases on the non-overlapping frequency domain resources, resulting in frequency-selective fading for UE0.

[0072] Therefore, the embodiments of the present application provide a communication method for reducing interference by reducing the rank (i.e., the number of spatial multiplexing streams) for downlink transmission by a terminal device, and related devices capable of implementing the method.

[0073] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0074] FIG. 6 is a diagram illustrating the architecture of a mobile communication system to which an embodiment of the present application is applied. The mobile communication system includes a core network device 110, a radio access network device 120, and at least one terminal device (e.g., terminal device 130 and terminal device 140 in the figure). The terminal device 130 is wirelessly connected to the radio access network device 120, which is connected to the core network device 110 wirelessly or via a wired connection. The core network device 110 and the radio access network device 120 may be independent and different physical devices, or the core network device's functions and the logical functions of the radio access network device may be integrated into one physical device, or some of the core network device's functions and some of the radio access network device's functions may be integrated into one physical device. The terminal device 130 may be located at a fixed location or may be mobile. FIG. 6 is merely an example. The communication system may further include other network devices, such as a radio relay device and a radio backhaul device, which are not shown in FIG. 6. The number of core network devices, the number of radio access network devices, and the number of terminal devices included in the mobile communication system are not limited in the embodiments of the present application.

[0075] The radio access network device 120 is an access device used by the terminal device 130 to wirelessly access a mobile communication system, and may be a base station NodeB, an evolved base station eNodeB, a base station of an NR mobile communication system, a base station of a future mobile communication system, an access node of a Wi-Fi system, etc. The specific technology and specific device type used by the radio access network device 120 are not limited to this embodiment of the present application.

[0076] The terminal device 130 may also be referred to as a terminal, user equipment (UE), mobile station (MS), mobile terminal (MT), etc. The terminal device may be a mobile phone, a tablet computer (Pad), a computer with a wireless transceiver function, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical surgery, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, etc.

[0077] The radio access network device 120 and the terminal device 130 may be deployed on the ground, may include indoor or outdoor devices, handheld devices or vehicle-mounted devices, may be deployed on water, or may be deployed on aircraft, balloons, and satellites in the air. The application scenarios of the radio access network device 120 and the terminal device 130 are not limited to this embodiment of the present application.

[0078] This embodiment of the present application is applicable to downlink transmission, in which the transmitting device is a radio access network device 120 and the corresponding receiving device is a terminal device 130.

[0079] The radio access network device 120 and the terminal device 130 can communicate with each other via a licensed spectrum, an unlicensed spectrum, or both the licensed and unlicensed spectrum. The radio access network device 120 and the terminal device 130 can communicate with each other via a sub-6G spectrum, a higher than 6G spectrum, or both the sub-6G spectrum and the higher than 6G spectrum. The spectrum resources used by the radio access network device 120 and the terminal device 130 are not limited in this embodiment of the present application.

[0080] 7 illustrates a communication method implemented by a network device according to an embodiment of the present application based on the system architecture illustrated in FIG. 6. The network device may be a base station. In this method, the network device can reduce interference by reducing the rank of downlink transmission of the scheduled terminal device. The procedure illustrated in FIG. 7 is described using an example in which the network device schedules a first terminal device for downlink data transmission.

[0081] See Figure 7. The method may include the following steps.

[0082] S701: The network device determines first downlink transmission parameters of a first terminal device based on a state of a downlink channel of the first terminal device, where the first downlink transmission parameters include a first rank.

[0083] In a possible implementation, the downlink channel is a PDSCH. In addition to the first rank, the first downlink transmission parameters can further include parameters such as MCS, precoding matrix indicator (PMI), etc. This is not limited in this embodiment of the present application.

[0084] In a possible implementation, the network device can transmit a reference signal to the first terminal device. The first terminal device can measure the reference signal transmitted from the network device, determine a state of a downlink channel based on the measurement result of the reference signal, and report channel state information to the network device. The network device can acquire the state of the downlink channel of the first terminal device based on the channel state information reported from the first terminal device.

[0085] S702: The network device determines the number of RBs occupied by the downlink data of the first terminal device based on the first downlink transmission parameters. Here, for clarity, the number of RBs occupied by the downlink data of the first terminal device determined based on the first downlink transmission parameters is referred to as the first number of RBs.

[0086] In a possible implementation, the network device may estimate the number of RBs occupied by the downlink data, i.e., the first number of RBs, based on the amount of downlink data to be transmitted to the first terminal device and first downlink transmission parameters (e.g., including parameters such as the first rank and MCS), where the first number of RBs is the number of RBs occupied by data transmitted on the downlink channel of the terminal device in one slot.

[0087] The network device may determine the first number of RBs occupied by the downlink data of the first terminal device based on the downlink transmission parameters of the first terminal device and the amount of downlink data, according to a method provided in the communication protocol or a method provided in the related technology.

[0088] For example, the downlink channel is a PDSCH. A possible implementation of S702 includes the following steps:

[0089] Step 1: The network device determines the number of REs allocated to the PDSCH of the first terminal device in one slot.

[0090] First, the number of REs allocated to the PDSCH in one physical resource block (PRB):

number

number

[0091]

number

number

number

number

number

number

number

[0092] And the total number of REs allocated to the PDSCH based on the number of REs in one PRB and the number of PRBs:

number

number

[0093]

number

[0094] Step 2: Number of first information bits N info Determine.

number

[0095] R is the target code rate for PDSCH. Q m is the modulation order of the PDSCH, and ν is the number of layers.

[0096] Step 3:N info Based on this, operations such as quantization and table lookup are performed to determine the transport block size (TBS) of data transmitted on the PDSCH of the first terminal device in one slot.

[0097] Step 4: Based on the TBS and the amount of downlink data to be transmitted to the first terminal device, determine the number of RBs occupied by the downlink data transmitted on the downlink channel of the first terminal device in one slot.

[0098] The above-described method for determining the number of RBs occupied by the downlink data of the first terminal device (i.e., the first number of RBs) is merely an example. The method for determining the number of RBs occupied by the downlink data of the first terminal device is not limited to this embodiment of the present application.

[0099] S703: The network device determines the number of remaining RBs based on the number of allocatable RBs and the first number of RBs. Here, for clarity, the number of remaining RBs is referred to as the first number of remaining RBs, or the number of remaining RBs corresponding to the first terminal device.

[0100] Optionally, in the case of single-user scheduling, the number of allocatable RBs is the number of RBs that can be allocated to a first terminal device among the RBs occupied by the downlink channel in one slot. For example, when the scheduled terminal device includes only the first terminal device and a first rank determined based on the state of the downlink channel of the first terminal device is greater than 1, the number of allocatable RBs is the number of RBs occupied by the downlink channel in one slot. As another example, when there are multiple scheduled terminal devices including the first terminal device and at least one other terminal device, and the rank determined based on the state of the downlink channel for the first terminal device is greater than 1 and the rank determined based on the state of the downlink channel for the other terminal devices is 1, the number of allocatable RBs is the number of RBs obtained by subtracting the number of RBs occupied by downlink data of at least one other terminal device from the number of RBs occupied by the downlink channel in one slot. As another example, if there are a plurality of scheduled terminal devices including a first terminal device, a second terminal device, and at least one other terminal device, and the rank determined based on the state of the downlink channel for the first terminal device and the second terminal device is greater than 1, and the rank determined based on the downlink channel for the other terminal devices is 1, the number of allocatable RBs is the number of RBs obtained by subtracting the number of RBs occupied by the downlink data of the second terminal device and the other terminal devices from the number of RBs occupied by the downlink channel in one slot. In this step, the downlink transmission parameter for determining the number of RBs occupied by the downlink data of the terminal devices is called a first downlink transmission parameter, and the first downlink transmission parameter is determined based on the state of the downlink channel of the terminal device.

[0101] Optionally, for multi-user scheduling, the total number of RBs occupied by the downlink data of the terminal devices in each MU group may be determined, and then the maximum value may be selected as the number of allocatable RBs for each MU group. The number of RBs occupied by the downlink data is determined based on a first downlink transmission parameter, such as the number of spatial multiplexing streams obtained before rank reduction is performed in each terminal device. For each terminal device, the first downlink transmission parameter of the terminal device is determined based on the state of the downlink channel of the terminal device.

[0102] In this example, the first terminal device is a terminal device in a first MU group among at least two MU groups based on multi-user scheduling. The at least two MU groups further include a second MU group. Since the total number of RBs occupied by the downlink data of the terminal devices in the second MU group is equal to or greater than the total number of RBs occupied by the downlink data of the terminal devices in the other MU groups, the total number of RBs occupied by the downlink data of the terminal devices in the second MU group is determined as the number of allocatable RBs for each MU group. That is, in MU groups other than the second MU group, the number of RBs occupied by the downlink data of the terminal devices in each MU group after reducing the rank of the terminal device cannot exceed the total number of RBs occupied by the downlink data of the terminal devices in the second MU group.

[0103] For example, MU group 1 includes UE0, MU group 2 includes UE1, and MU group 3 includes UE2. Based on the state of the downlink channel, UE0 uses Rank 1, and UE1 and UE2 use Rank 4. The number of RBs occupied by the downlink data of UEs in each MU group is determined based on the rank used by each UE and the amount of downlink data of each UE. UE0's downlink data occupies the largest number of RBs. Therefore, the number of RBs occupied by the downlink data of UEs in MU group 1 is determined as the total number of allocatable RBs for UEs in MU group 2 and the total number of allocatable RBs for UEs in MU group 3. In other words, the total number of allocatable RBs for UEs in MU group 2 and the total number of allocatable RBs for UEs in MU group 3 are equal to the number of RBs occupied by the downlink data of UEs in MU group 1.

[0104] In this embodiment of the present application, in order to avoid an excessive increase in the number of RBs occupied by the downlink data of the terminal device in each MU group after the rank of the terminal device in the MU group is reduced, the number of RBs occupied by the downlink data of the terminal device in each MU group is limited as described above.

[0105] The network device may subtract the first number of RBs corresponding to the first terminal device from the number of allocatable RBs to obtain the first number of remaining RBs corresponding to the first terminal device.

[0106] S704: If the first terminal device satisfies at least the first condition, execute S705.

[0107] The first terminal device satisfying at least the first condition can be understood as at least guaranteeing that, for the first terminal device, the first remaining number of RBs corresponding to the first terminal device can support a reduction from the first rank of the first terminal device to the second rank. The number of spatial multiplexing streams indicated by the second rank is less than the number of spatial multiplexing streams indicated by the first rank. For example, the first rank is Rank 4 and the second rank is Rank 2. In another example, the first rank is Rank 4 and the second rank is Rank 1. In another example, the first rank is Rank 2 and the second rank is Rank 1.

[0108] In other words, the first condition can also be expressed as follows: The first remaining number of RBs is equal to or greater than the difference between the second number of RBs and the first number of RBs. The second number of RBs is the number of RBs occupied by downlink data of the first terminal device, determined based on second downlink transmission parameters. The second downlink transmission parameters include a second rank, where the number of spatial multiplexing streams indicated by the second rank is less than the number of spatial multiplexing streams indicated by the first rank, and the second number of RBs is greater than the first number of RBs.

[0109] Optionally, the first downlink transmission parameters of the first terminal device include a first MCS, and the second downlink transmission parameters of the first terminal device include a second MCS, where the first MCS is equal to the second MCS. In other words, the network device may maintain the MCS of the terminal device unchanged before and after reducing the rank of the first terminal device. Of course, this embodiment of the present application does not exclude that the rank of the first terminal device may be reduced and the MCS of the first terminal device may be adjusted.

[0110] It can be understood that the number of RBs occupied by downlink data increases after the rank is reduced. For example, if the MCS is kept unchanged, the number of RBs occupied by downlink data may be doubled after the rank is reduced from Rank 4 to Rank 2. If the first remaining number of RBs is equal to or greater than the difference between the second number of RBs and the first number of RBs, this indicates that the increment in the number of RBs occupied by downlink data after the rank is reduced is less than the first remaining number of RBs. In other words, the first remaining number of RBs may support a reduction from the first rank to the second rank of the first terminal device.

[0111] In a possible implementation, the network device may first determine second downlink transmission parameters based on the first downlink transmission parameters. For example, the network device may adjust some parameters of the first downlink transmission parameters while keeping other transmission parameters unchanged to obtain a new group of downlink transmission parameters, i.e., second downlink transmission parameters. For example, the rank of the first downlink transmission parameters may be decreased, specifically, from the first rank to the second rank, while keeping other parameters (e.g., MCS) unchanged. In this case, a new group of downlink transmission parameters is obtained, which is referred to as second downlink transmission parameters. The rank of the second downlink transmission parameters is second rank, and the MCS of the second downlink transmission parameters is the same as the MCS of the first downlink transmission parameters. Next, the network device determines a second number of RBs occupied by the downlink data of the first terminal device based on the second downlink transmission parameters. For specific implementations, see the above description. Finally, the network device may determine whether the first terminal device satisfies a first condition based on the determined first remaining number of RBs, the determined first number of RBs, and the determined second number of RBs corresponding to the first terminal device, and based on the determination result, decide whether to perform downlink data transmission with the first terminal device based on the first downlink transmission parameters, or to perform downlink data transmission with the first terminal device based on the second downlink transmission parameters.

[0112] Optionally, when reducing the rank of the first terminal device, the network device may reduce the rank of the terminal device to an appropriate value based on the amount of downlink data of the terminal device and the first remaining number of RBs, and may fully use the remaining RBs to reduce the rank as much as possible. For example, when the MCS is maintained unchanged, the network device may determine that the first terminal device is using Rank 4 based on the state of the downlink channel of the first terminal device. The amount of downlink data transmitted by the network device to the first terminal device is small, and there are still RBs available for allocation within the slot. If the first remaining number of RBs determined by the network device supports a reduction of the first terminal device from Rank 4 to Rank 2 or a reduction of the first terminal device from Rank 4 to Rank 1, the network device may reduce the number of spatial multiplexing streams of the first terminal device from Rank 4 to Rank 1.

[0113] For example, Figure 8 is a diagram illustrating reducing interference by reducing the rank of a UE in a single-user scheduling scenario. As shown in the figure, the network device determines, based on the PDSCH states of UE0 and UE1, that UE0 currently uses Rank1 and UE1 currently uses Rank4. The network device determines the number of RBs occupied by UE1's downlink data based on the amount of UE1's downlink data and the downlink transmission parameters used by UE1 (including the number of spatial multiplexing streams used by UE1), and may further determine the number of remaining allocatable RBs. The network device determines that the number of remaining RBs can support a reduction in the number of spatial multiplexing streams of UE1 from Rank4 to Rank2. Therefore, the network device reduces the number of spatial multiplexing streams of UE1 to Rank2.

[0114] S705: The network device performs downlink data transmission with the first terminal device based on the second downlink transmission parameters.

[0115] If the first terminal device satisfies the first condition, the network device can perform downlink data transmission with the first terminal device based on the second downlink data transmission parameters (including a reduced rank) of the first terminal device, and reduce interference based on ensuring data transmission.

[0116] Also, in S704, if the network device determines that the first terminal device does not satisfy the first condition, it performs the following steps:

[0117] S706: The network device performs downlink data transmission with the first terminal device based on the first downlink transmission parameter of the first terminal device.

[0118] Note that the RB in the above procedure may be replaced with a physical resource block (PRB). There is a correspondence between the RB and the PRB, and the corresponding PRB can be obtained after mapping the RB to the physical layer. In some scenarios, the RB has a one-to-one correspondence with the PRB.

[0119] In the above-mentioned embodiment of the present application, when scheduling downlink transmission for a terminal device, the network device further considers the RB utilization rate (or PRB utilization rate) and downlink traffic volume of the terminal device based on the channel state, and based on ensuring downlink data transmission of the terminal device, reduces the rank to reduce the interference level and the number of interference sources, thereby improving the interference suppression effect of demodulation of the terminal device in the adjacent cell.

[0120] In a possible implementation, based on one or more of the above-mentioned embodiments, the network device may further reduce the transmission power of the first terminal device before performing downlink data transmission with the first terminal device based on the second downlink transmission parameter, thereby reducing the transmission power without affecting the downlink transmission quality of the first terminal device and saving energy.

[0121] Optionally, the amount of transmission power reduction of a terminal device (e.g., a first terminal device) may be determined using the principle that the MCS of the terminal device remains unchanged before and after reducing the transmission power. The MCS is determined based on the state of the downlink channel of the terminal device. In a possible implementation, MCS1 is used to represent the MCS determined based on the state of the downlink channel of the first terminal device. That is, MCS1 is the MCS obtained before the rank reduction process is performed on the first terminal device. Based on MCS1, the network device can query a mapping table from signal-to-interference plus noise ratio (SINR, or signal-to-interference plus noise ratio for short) to MCS to obtain the signal-to-interference plus noise ratio (for ease of explanation, the signal-to-interference plus noise ratio is referred to as SINR1 here) corresponding to MCS1. After the network device reduces the rank of the first terminal device, the signal-to-interference and noise ratio of the downlink channel of the first terminal device increases due to a reduction in the number of spatial multiplexing streams or other reasons (here, for ease of explanation, the signal-to-interference and noise ratio obtained after reducing the rank of the first terminal device is referred to as SINR2). The network device can determine the amount of power reduction based on the increase in the signal-to-interference and noise ratio (i.e., the difference obtained by subtracting SINR1 from SINR2). Of course, the above implementations are only possible examples, and the method of determining the amount of transmission power reduction is not limited to this embodiment of the present application.

[0122] In the above embodiment of the present application, decreasing the rank of the terminal device further reduces the transmission power of the terminal device, thereby further reducing interference and further saving energy.

[0123] Based on the procedure of FIG. 7, in a single-user scheduling scenario, the following cases are possible:

[0124] Case 1-1: When there is only one scheduled terminal device and the number of spatial multiplexing streams of the terminal device is greater than 1, that is, when there is a possibility of reducing the rank of the terminal device, the network device determines whether the number of remaining RBs can support reducing the rank of the terminal device based on the procedure shown in Figure 7. If the number of remaining RBs supports reducing the rank of the terminal device, the network device determines that the terminal device satisfies the first condition and can perform downlink data transmission with the terminal device based on the reduced rank.

[0125] Case 1-2: When there are multiple scheduled terminal devices and the numbers of all spatial multiplexing streams of the multiple terminal devices are greater than 1, that is, when the multiple terminal devices may each reduce their rank, the network device determines, for each of the multiple terminal devices, whether the number of remaining RBs of each terminal device satisfies the condition for reducing the rank based on the procedure shown in Figure 7. When the number of remaining RBs of each terminal device satisfies the condition for reducing the rank and the number of RBs of the downlink channel in the slot supports simultaneously reducing the ranks of multiple terminal devices, the network device can reduce the ranks of the multiple terminal devices individually and perform downlink data transmission with the multiple terminal devices based on the reduced ranks.

[0126] Case 1-3: When there are multiple scheduled terminal devices and the number of spatial multiplexing streams of all of the multiple terminal devices is greater than 1, that is, when multiple terminal devices may each lower their rank, the network device determines, for each of the multiple terminal devices, whether the number of remaining RBs of each terminal device satisfies the condition for lowering the rank based on the procedure shown in FIG. 7. If the number of remaining RBs of each terminal device satisfies the condition for lowering the rank but the number of RBs of the downlink channel in the slot cannot support simultaneously lowering the ranks of multiple terminal devices, the network device may select one or more of the terminal devices. If the number of RBs of the downlink channel in the slot supports simultaneously lowering the ranks of one or more terminal devices, the network device lowers the ranks of the selected one or more terminal devices and performs downlink data transmission with the selected one or more terminal devices based on the reduced ranks.

[0127] For example, the at least two terminal devices based on single-user scheduling include a first terminal device and a second terminal device. The numbers of spatial multiplexing streams determined based on the states of the downlink channels of the first terminal device and the second terminal device are both greater than 1. For the first terminal device, the network device determines a first number of remaining RBs corresponding to the first terminal device based on the procedure shown in Figure 7. For the second terminal device, the network device determines a second number of remaining RBs corresponding to the second terminal device based on the procedure shown in Figure 7. The second number of remaining RBs is determined based on the number of allocatable RBs and the number of RBs occupied by downlink data of the second terminal device.

[0128] If the first remaining number of RBs of the first terminal device supports a decrease from the first rank to the second rank of the first terminal device, and the second remaining number of RBs of the second terminal device supports a decrease from the third rank (the third rank is determined based on the state of the downlink channel of the second terminal device) to the fourth rank of the second terminal device, but when the decrease from the first rank to the second rank of the first terminal device is made, the first remaining number of RBs does not support a decrease from the third rank to the fourth rank of the second terminal device (i.e., when the decrease from the first rank to the second rank of the first terminal device is made, the second remaining number of RBs does not support a decrease from the third rank to the fourth rank of the second terminal device), the network device selects one terminal device from the first terminal device and the second terminal device, for example, selects the first terminal device, and for the first terminal device, performs downlink data transmission with the first terminal device based on the second downlink transmission parameters of the terminal device.

[0129] Furthermore, with respect to the second terminal device, the network device performs downlink data transmission with the second terminal device using downlink transmission parameters (i.e., the first downlink transmission parameters of the second terminal device) determined based on the state of the downlink channel of the second terminal device, and does not reduce the rank of the downlink transmission parameters.

[0130] Furthermore, the selected first terminal device further satisfies a second condition, and the second condition includes that the strength of interference of the first terminal device to a neighboring cell is greater than the strength of interference of the second terminal device to a neighboring cell. When the network device selects multiple terminal devices that can reduce their ranks, it is understood that the strength of interference of the multiple terminal devices to neighboring cells is greater than the strength of interference of the terminal devices that are not selected to reduce their ranks to neighboring cells. That is, in this case, the strength of interference of the terminal devices to neighboring cells may be determined, and the terminal device with the greater strength of interference may be preferentially selected for rank reduction scheduling.

[0131] Optionally, the strength of interference of the terminal device with respect to neighboring cells may be determined based on a measurement report reported by the terminal device, for example, based on an A3 measurement report reported by the terminal device. The A3 measurement report may include parameters such as reference signal received power (RSRP) of the neighboring cells measured by the terminal device, and may be used to determine the strength of interference with the neighboring cells. Of course, alternatively, the strength of interference of the terminal device with respect to neighboring cells may be determined in a different manner, which is not limited to this embodiment of the present application.

[0132] For example, Figure 9 is a diagram illustrating a UE for which a rank is to be reduced based on interference identification in an SU scheduling scenario according to an embodiment of the present application. As shown in the figure, the network device determines, based on the PDSCH states of UE0, UE1, and UE2, that UE0 currently uses Rank 1, and UE1 and UE2 currently use Rank 4. The network device determines the number of RBs occupied by the downlink data of UE1 and UE2 based on the current data volume of the downlink data of UE1 and UE2 and the downlink transmission parameters used by UE1 and UE2 (including the number of spatial multiplexing streams used by UE1 and UE2). The network device further determines that the number of remaining RBs can support a reduction in the rank of one of UE1 and UE2, but cannot support a simultaneous reduction in the ranks of the two UEs. Because UE1's interference to a neighboring cell is greater than UE2's interference to a neighboring cell, the network device selects UE1 for a rank reduction and reduces UE1's Rank 4 to Rank 2.

[0133] Here, only the first terminal device and the second terminal device will be described as an example, but when N terminal devices (N is an integer greater than 1) each satisfy the first condition for rank reduction but the ranks of the N terminal devices cannot be reduced simultaneously, if the network device determines that the ranks of some of the terminal devices can be reduced simultaneously, the network device can select some of the terminal devices, reduce the ranks of the terminal devices, and perform downlink data transmission with some of the terminal devices based on the downlink transmission parameters obtained after the rank reduction. For example, the network device can select terminal devices as follows and perform rank reduction processing for the selected terminal devices:

[0134] Step 1: The network device determines M combinations (M is an integer equal to or greater than 1) based on N terminal devices, each combination including at least one of the N terminal devices, and for each combination, the number of allocatable RBs corresponding to the MU group can support simultaneous reduction of the ranks of the terminal devices in the combination.

[0135] Step 2: The network device determines the sum of the interference strengths of the terminal devices to the neighboring cells in each combination.

[0136] Step 3: The network device selects the combination with the greatest sum of interference strength from among the M combinations based on the sum of interference strength of the terminal devices in each combination with the neighboring cells. The network device performs rank reduction processing on the terminal devices of the selected combination. For combinations that are not selected, the network device does not perform rank reduction processing on the terminal devices of that combination.

[0137] In this embodiment of the present application, a terminal device with high interference strength with neighboring cells is selected, and rank reduction scheduling is performed preferentially for that terminal device. In this case, the number of interference sources for users in neighboring cells can be reduced, and the interference suppression gain of IRC technology can be obtained. According to the above method, an interference mitigation scheduling solution can be flexibly selected based on PRB load and interference information, making maximum use of RB resources, minimizing interference, and improving system performance.

[0138] Based on the procedure of FIG. 7, in a multi-user scheduling scenario, the following cases are possible:

[0139] Case 2-1: If the ranks of all terminal devices in an MU group whose number of spatial multiplexing streams is greater than 1 can be simultaneously reduced based on the number of allocatable RBs corresponding to the MU group, the network device can reduce the ranks of all terminal devices in the MU group whose number of spatial multiplexing streams is greater than 1, and perform downlink data transmission with the terminal devices based on the reduced ranks.

[0140] For example, Figure 10 is a diagram illustrating a rank reduction in an MU scheduling scenario according to an embodiment of the present application. As shown in the figure, MU group 1 includes UE0, MU group 2 includes UE1, and MU group 3 includes UE2. Because the downlink data of UEs in MU group 1 occupies the largest number of RBs, the number of RBs occupied by the downlink data of UEs in MU group 1 is used as the upper limit of the number of allocatable RBs corresponding to each MU group. Based on the procedure shown in Figure 7, the network device determines that UE1 in MU group 2 and UE3 in MU group 2 may satisfy the rank reduction condition. Therefore, the network device performs a rank reduction process on UE1 and UE2, reducing UE2's Rank2 to Rank1 and UE2's Rank2 to Rank1.

[0141] Case 2-2: If it is not possible to simultaneously reduce the ranks of all terminal devices in one MU group whose number of spatial multiplexing streams is greater than 1 based on the number of allocatable RBs corresponding to the MU group, the network device selects one or more of the terminal devices, and the number of RBs of the downlink channel in the slot can support simultaneous reduction of the ranks of one or more terminal devices. The network device reduces the ranks of the selected one or more terminal devices and performs downlink data transmission with the selected one or more terminal devices based on the reduced ranks.

[0142] For example, a first MU group based on multi-user scheduling includes a first terminal device and a second terminal device, and the network device may separately determine a first remaining number of RBs corresponding to the first terminal device in the MU group after reducing the rank of the first terminal device and a second remaining number of RBs corresponding to the second terminal device in the MU group after reducing the rank of the second terminal device, based on the procedure shown in Figure 7. If the first remaining RB number corresponding to the first terminal device supports a decrease from the first rank to the second rank of the first terminal device, and the second remaining RB number corresponding to the second terminal device supports a decrease from the third rank (the third rank is determined based on the state of the downlink channel of the second terminal device) to the fourth rank of the second terminal device, but when the decrease from the first rank to the second rank of the first terminal device is made, the first remaining RB number does not support a decrease from the third rank to the fourth rank of the second terminal device (i.e., when the decrease from the first rank to the second rank of the first terminal device is made, the second remaining RB number does not support a decrease from the third rank to the fourth rank of the second terminal device), the network device selects one terminal device from the first terminal device and the second terminal device, for example, selects the first terminal device, and for the first terminal device, performs downlink data transmission with the first terminal device based on the second downlink transmission parameters of the terminal device.

[0143] Also, with respect to the second terminal device, the network device performs downlink data transmission with the second terminal device using downlink transmission parameters determined based on the state of the downlink channel of the second terminal device, and the rank of the downlink transmission parameters is not reduced.

[0144] Here, only the first terminal device and the second terminal device will be described as examples, but when multiple terminal devices each satisfy the first condition for rank reduction but the ranks of the multiple terminal devices cannot be reduced simultaneously, if the network device determines that the ranks of some of the terminal devices can be reduced simultaneously, the network device can select some of the terminal devices and reduce the ranks of the terminal devices, and perform downlink data transmission with some of the terminal devices based on the downlink transmission parameters obtained after the rank reduction.

[0145] In the above-described embodiment of the present application, in an MU scheduling scenario, when scheduling downlink transmissions for a terminal device, the network device further considers the RB utilization rate (or PRB utilization rate) and downlink traffic volume of the terminal device based on the channel state. Based on ensuring the terminal device's downlink data transmission, the rank is reduced to reduce interference and the number of interference sources, thereby reducing interference between MU groups and mitigating the problem of frequency-selective fading in MU groups with high traffic transmission requirements caused by MU pairing combination. Furthermore, after reducing the number of MU pairing combination layers, the number of interference sources for UEs in neighboring cells is reduced. In this case, the IRC capabilities of the terminal device's receiving side can be fully utilized, improving interference suppression performance.

[0146] Optionally, the selected first terminal device further satisfies a third condition. The third condition is that the scheduling priority of the first terminal device is higher than the scheduling priority of the second terminal device. When the network device selects multiple terminal devices that can be reduced in rank, it is understood that the scheduling priorities of the multiple terminal devices are not lower than the scheduling priorities of terminal devices that are not selected for rank reduction. That is, in this case, terminal devices with high scheduling priorities may be preferentially selected for rank reduction scheduling to reduce the interference of terminal devices with high scheduling priorities.

[0147] Optionally, the third condition may alternatively be that the strength of interference of the first terminal device to the adjacent cell is greater than the strength of interference of the second terminal device to the adjacent cell. When the network device selects multiple terminal devices that can reduce their ranks, it is understood that the strength of interference of the multiple terminal devices to the adjacent cells is greater than or equal to the strength of interference of the terminal devices that are not selected to reduce their ranks to the adjacent cells. In other words, in this case, the terminal device with greater interference strength to the adjacent cells may be preferentially selected for rank reduction scheduling to reduce the interference to the neighboring cells.

[0148] Case 2-3: Similar to the above-mentioned Case 2-2, when the number of remaining RBs in one MU group cannot support simultaneous reduction in the rank of multiple terminal devices, the network device can select a terminal device with a large amount of power reduction and reduce the rank of the terminal device.

[0149] An example will be described in which both a first terminal device and a second terminal device of an MU group satisfy the rank reduction processing condition, but the allocatable RBs corresponding to the MU group cannot support simultaneous rank reduction processing for the first terminal device and the second terminal device. In this case, the network device may determine a corresponding first transmission power reduction amount based on the first MCS of the first terminal device (i.e., the MCS determined based on the state of the downlink channel of the first terminal device), determine a corresponding second transmission power reduction amount based on the first MCS of the second terminal device (i.e., the MCS determined based on the state of the downlink channel of the second terminal device), and select the first terminal device for rank reduction processing if the first transmission power reduction amount is greater than the second transmission power reduction amount. For the second terminal device, downlink data transmission is performed using downlink transmission parameters determined based on the downlink channel of the second terminal device (i.e., rank reduction processing is not performed for the second terminal device), and transmission power reduction processing is not performed for the second terminal device.

[0150] Here, we will only use an example where the MU group includes a first terminal device and a second terminal device, but if the MU group includes multiple terminal devices (e.g., N devices, where N is an integer greater than 1) with a number of spatial multiplexing streams greater than 1, and the N terminal devices individually satisfy the first rank reduction condition, but the ranks of the N terminal devices cannot be reduced simultaneously, the network device can select a terminal device as follows and perform rank reduction processing on the selected terminal device.

[0151] Step 1: The network device determines M combinations (M is an integer equal to or greater than 1) based on the N terminal devices included in the MU group. Each combination includes at least one of the N terminal devices, and for each combination, the number of allocatable RBs corresponding to the MU group can support simultaneous reduction of the ranks of the terminal devices in the combination.

[0152] Step 2: The network device determines the transmission power reduction amount corresponding to each combination. The transmission power reduction amount corresponding to one combination is the sum of the transmission power reduction amounts of all the terminal devices included in that combination. For the method of determining the transmission power reduction amount of the terminal device, please refer to the above description.

[0153] Step 3: Based on the transmission power reduction amount, select the combination with the largest transmission power reduction amount from among the M combinations. The network device performs rank reduction processing on the terminal devices of the selected combination and performs transmission power reduction processing. For combinations that are not selected, the network device does not perform rank reduction processing on the terminal devices of that combination and does not perform transmission power reduction processing.

[0154] Case 2-4: Similar to the scenario in Case 2-2 above, if one MU group satisfies multiple rank reduction solutions, for example, if it satisfies rank reduction solution 1 that reduces UE1 in the MU group from Rank 4 to Rank 2 and UE2 in the MU group from Rank 4 to Rank 2, and also satisfies rank reduction solution 2 that reduces UE1 in the MU group from Rank 4 to Rank 1, the network device can select one of the rank reduction solutions and perform the rank reduction processing.

[0155] Based on the same technical concept, an embodiment of the present application further provides a communication device. The communication device can implement the functions implemented by the network device of the above embodiment. The communication device may be a network device (e.g., a base station) or a communication module applied to a network device (e.g., a base station). The communication device may be implemented by software, hardware, or a combination of hardware and software. As shown in FIG. 11, a communication device 1100 may include a processing unit 1101 and a transceiver unit 1102.

[0156] The processing unit 1101 is configured to determine first downlink transmission parameters of the first terminal device based on the state of the downlink channel of the first terminal device, the first downlink transmission parameters including a first rank; determine a first number of RBs occupied by downlink data of the first terminal device based on the first downlink transmission parameters; determine a first remaining number of RBs based on the number of allocatable RBs and the first number of RBs; and, when the first terminal device satisfies at least a first condition, perform downlink data transmission with the first terminal device based on second downlink transmission parameters using the transceiver unit 1102, the second downlink transmission parameters including a second rank, the number of spatial multiplexing streams indicated by the second rank being less than the number of spatial multiplexing streams indicated by the first rank, and the first condition including that the first remaining number of RBs supports a reduction from the first rank to the second rank of the first terminal device.

[0157] In a possible implementation, the first terminal device is one of at least two terminal devices based on single-user scheduling, and the at least two terminal devices further include a second terminal device, and the numbers of both spatial multiplexing streams determined based on the states of the downlink channels of the first terminal device and the second terminal device are greater than 1, the first number of remaining RBs of the first terminal device supports a reduction from the first rank to the second rank for the first terminal device, and the second number of remaining RBs of the second terminal device supports a reduction from the third rank to the fourth rank for the second terminal device, but when the reduction from the first rank to the second rank is performed for the first terminal device, the first number of remaining RBs does not support a reduction from the third rank to the fourth rank for the second terminal device. The second number of remaining RBs is determined based on the number of allocatable RBs and the number of RBs occupied by downlink data of the second terminal device, and the third rank is determined based on the state of the downlink channel of the second terminal device. The processing unit 1101 is specifically configured to select a first terminal device from a first terminal device and a second terminal device, and use the transceiver unit 1102 to perform downlink data transmission with the first terminal device based on second downlink transmission parameters.

[0158] In a possible embodiment, the processing unit 1101 is specifically configured to select a first terminal device from the first terminal device and the second terminal device if the first terminal device further satisfies a second condition, wherein the second condition includes that the interference strength of the first terminal device to a neighboring cell is greater than the interference strength of the second terminal device to a neighboring cell.

[0159] In a possible implementation, the first terminal device is a terminal device in a first multi-user group of at least two multi-user groups based on multi-user scheduling, the at least two multi-user groups further including a second multi-user group, the number of allocatable RBs is the total number of RBs occupied by downlink data of the terminal devices in the second multi-user group, and the total number of RBs occupied by downlink data of the terminal devices in the second multi-user group is greater than or equal to the total number of RBs occupied by downlink data of the terminal devices in each of the at least two multi-user groups.

[0160] In a possible implementation, the first multi-user group further includes a second terminal device, and the numbers of both spatial multiplexing streams determined based on the states of the downlink channels of the first terminal device and the second terminal device are greater than 1, the first remaining number of RBs of the first terminal device supports a reduction from the first rank to the second rank for the first terminal device, and the second remaining number of RBs of the second terminal device supports a reduction from the third rank to the fourth rank for the second terminal device, but when the reduction from the first rank to the second rank is performed for the first terminal device, the first remaining number of RBs does not support a reduction from the third rank to the fourth rank for the second terminal device. The second remaining number of RBs of the second terminal device is determined based on the number of allocatable RBs and the number of RBs occupied by downlink data of the second terminal device, and the third rank is determined based on the states of the downlink channel of the second terminal device. The processing unit 1101 is specifically configured to select the first terminal device from the first terminal device and the second terminal device, and to perform downlink data transmission with the first terminal device based on the second downlink transmission parameters using the transceiver unit 1102.

[0161] In a possible embodiment, the processing unit 1101 is specifically configured to select a first terminal device from the first terminal device and the second terminal device if the first terminal device further satisfies a third condition, which includes: the scheduling priority of the first terminal device is higher than the scheduling priority of the second terminal device, or the interference strength of the first terminal device to a neighboring cell is greater than the interference strength of the second terminal device to a neighboring cell.

[0162] In a possible implementation, the processing unit 1101 is configured to: determine a corresponding first transmission power reduction amount based on a first MCS of the first terminal device; determine a corresponding second transmission power reduction amount based on the first MCS of the second terminal device; and select the first terminal device from the first terminal device and the second terminal device if the first transmission power reduction amount is greater than the second transmission power reduction amount. Further, the processing unit 1101 is configured to reduce the transmission power of the transceiver unit 1102 for the first terminal device based on the first transmission power reduction amount before performing downlink data transmission with the first terminal device based on the second downlink transmission parameters.

[0163] In a possible implementation, the processing unit 1101 is further configured to reduce the transmission power of the transceiver unit 1102 for the first terminal device before downlink data transmission with the first terminal device is performed based on the second downlink transmission parameters.

[0164] In a possible implementation, the first downlink transmission parameters further include a first modulation and coding scheme (MCS), and the second downlink transmission parameters further include a second MCS, where the first MCS is equal to the second MCS.

[0165] It should be understood that the communication device provided in this embodiment of the present application can implement all the method steps implemented by the network device in the above-mentioned method embodiment, and can achieve the same technical effects, and the same parts and beneficial effects of this embodiment as those of the method embodiment will not be specifically described again here.

[0166] 12 shows only the structure necessary for the communication device 1200 to perform the method described herein, and the present application does not impose any limitation on the communication device having more components. The communication device 1200 may be configured to perform steps performed by related devices in the above-described method embodiments. For example, the related devices may be terminal devices or network devices.

[0167] The communications device 1200 includes a transceiver 1201, a memory 1203, and a processor 1202. The transceiver 1201, the memory 1203, and the processor 1202 may be connected to each other via a bus 1204. The transceiver 1201 may be used by the communications device to communicate, such as by transmitting and receiving signals. The memory 1203 may be coupled to the processor 1202 and configured to store programs and data necessary for the communications device 1200 to perform functions. The memory 1203 and the processor 1202 may be integrated or separate from each other.

[0168] For example, the transceiver 1201 may be a communication port, e.g., a communication port (also called an interface) used for communication between network elements. The transceiver 1201 may also be called a transceiver unit or a communication unit. The processor 1202 may be implemented using a processing chip or processing circuit. The transceiver 1201 may receive or transmit information wirelessly or via a wired method.

[0169] Furthermore, based on actual usage requirements, the communication device provided in this embodiment of the present application may include a processor, and the processor calls an external transceiver and / or memory to realize the above-mentioned functions, steps or operations. The communication device may further include a memory, and the processor calls and executes a program stored in the memory to realize the above-mentioned functions, steps or operations. Alternatively, the communication device may include a processor and a transceiver (or a communication interface), and the processor calls and executes a program stored in the external memory to realize the above-mentioned functions, steps or operations. Alternatively, the communication device may include a processor, a memory, and a transceiver.

[0170] Based on the same concept as the above method embodiments, an embodiment of the present application further provides a computer-readable storage medium, which stores program instructions (also referred to as computer programs or instructions), which, when executed by a processor, enable the computer to perform the operations performed by the network device in the above method embodiments and any possible implementations of the above method embodiments.

[0171] Based on the same concept as the aforementioned method embodiments, the present application further provides a computer program product including program instructions, which, when invoked and executed by a computer, enables the computer to perform the operations performed by the network device in the aforementioned method embodiments and any possible implementations of the aforementioned method embodiments.

[0172] Based on the same concept as the above-mentioned method embodiment, the present application further provides a chip or a chip system, wherein the chip is coupled to a transceiver and configured to perform the operations performed by a terminal device or a network device in the above-mentioned method embodiment and any possible embodiments of the above-mentioned method embodiment. The chip system may include a chip and components such as a memory and a communication interface.

[0173] Based on the same concept as the above-mentioned method embodiment, an embodiment of the present application further provides a communication system, optionally including a terminal device and a network device, wherein the network device can perform the operations of the network device in the above-mentioned method embodiment.

[0174] Those skilled in the art should understand that the embodiments of the present application may be provided as a method, a system, or a computer program product. Therefore, the present application may take the form of a hardware-only embodiment, a software-only embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product embodied in one or more computer-usable storage media (including, but not limited to, disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code.

[0175] The present application has been described with reference to flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to the present application. It should be understood that computer program instructions may be used to implement each process and / or each block in the flowcharts and / or block diagrams, and / or combinations of processes and / or blocks in the flowcharts and / or block diagrams. These computer program instructions may be provided to create a machine for a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or any other programmable data processing apparatus. As a result, the instructions, when executed by the processor of the computer or any other programmable data processing apparatus, create an apparatus that implements the particular function of one or more processes in the flowcharts and / or one or more blocks in the block diagrams.

[0176] These computer program instructions may be stored in a computer-readable memory and can instruct a computer or any other programmable data processing apparatus to operate in a particular manner. As a result, the instructions stored in the computer-readable memory create an article that includes an instruction apparatus that implements a particular function in one or more processes in the flowcharts and / or one or more blocks in the block diagrams.

[0177] These computer program instructions may alternatively be loaded into a computer or other programmable data processing apparatus such that a series of operations and steps are executed by the computer or other programmable apparatus, thereby generating a computer-implemented process. Thus, the instructions executed by the computer or other programmable apparatus provide steps for implementing a particular function in one or more processes in the flowcharts and / or one or more blocks in the block diagrams.

[0178] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the scope of protection of the present application. In this case, if the modifications and variations made to the present application are within the scope of the claims of the present application and their equivalent technologies, the present application shall also cover such modifications and variations.

Claims

1. 1. A method of communication, the method comprising: determining first downlink transmission parameters of a first terminal device based on a condition of a downlink channel of the first terminal device, the first downlink transmission parameters including a first rank; determining a first number of resource blocks (RBs) occupied by downlink data of the first terminal device based on the first downlink transmission parameters; determining a first number of remaining RBs based on the number of allocatable RBs and the first number of RBs; performing downlink data transmission with the first terminal device based on second downlink transmission parameters when the first terminal device satisfies at least a first condition, wherein the second downlink transmission parameters include a second rank, the number of spatial multiplexing streams indicated by the second rank is less than the number of spatial multiplexing streams indicated by the first rank, and the first condition includes that the first remaining number of RBs supports a decrease from the first rank of the first terminal device to the second rank; A method comprising:

2. the first terminal device is one of at least two terminal devices based on single-user scheduling, and the at least two terminal devices further include a second terminal device, wherein the numbers of both spatial multiplexing streams determined based on the state of the downlink channel of the first terminal device and the second terminal device are greater than 1, the first number of remaining RBs of the first terminal device supports a reduction from the first rank to the second rank of the first terminal device, and the second number of remaining RBs of the second terminal device supports a reduction from the third rank to the fourth rank of the second terminal device, but when the reduction from the first rank to the second rank of the first terminal device is performed, the first number of remaining RBs does not support a reduction from the third rank to the fourth rank of the second terminal device, the second number of remaining RBs is determined based on the number of allocatable RBs and the number of RBs occupied by downlink data of the second terminal device, and the third rank is determined based on the state of the downlink channel of the second terminal device; When the first terminal device satisfies at least a first condition, performing downlink data transmission with the first terminal device based on second downlink transmission parameters includes: selecting the first terminal device from the first terminal device and the second terminal device; performing downlink data transmission with the first terminal device based on the second downlink transmission parameters; The method of claim 1 , comprising:

3. The step of selecting the first terminal device from the first terminal device and the second terminal device includes: selecting the first terminal device from the first terminal device and the second terminal device if the first terminal device further satisfies a second condition; The method of claim 2 , wherein the second condition includes that the strength of interference of the first terminal device to a neighboring cell is greater than the strength of interference of the second terminal device to a neighboring cell.

4. 2. The method of claim 1, wherein the first terminal device is a terminal device in a first multi-user group of at least two multi-user groups based on multi-user scheduling, the at least two multi-user groups further including a second multi-user group, the number of allocatable RBs is the total number of RBs occupied by downlink data of the terminal devices in the second multi-user group, and the total number of RBs occupied by the downlink data of the terminal devices in the second multi-user group is equal to or greater than the total number of RBs occupied by downlink data of the terminal devices in each of the at least two multi-user groups.

5. the first multi-user group further includes a second terminal device, and the numbers of both spatial multiplexing streams determined based on the state of the downlink channel of the first terminal device and the second terminal device are greater than 1; the first number of remaining RBs of the first terminal device supports a reduction from the first rank to the second rank of the first terminal device, and the second number of remaining RBs of the second terminal device supports a reduction from the third rank to the fourth rank of the second terminal device, but when the reduction from the first rank to the second rank of the first terminal device is performed, the first number of remaining RBs does not support a reduction from the third rank to the fourth rank of the second terminal device; the second number of remaining RBs of the second terminal device is determined based on the number of allocatable RBs and the number of RBs occupied by downlink data of the second terminal device, and the third rank is determined based on the state of the downlink channel of the second terminal device; When the first terminal device satisfies at least a first condition, performing downlink data transmission with the first terminal device based on second downlink transmission parameters includes: selecting the first terminal device from the first terminal device and the second terminal device; performing downlink data transmission with the first terminal device based on the second downlink transmission parameters; The method of claim 4, comprising:

6. The step of selecting the first terminal device from the first terminal device and the second terminal device includes: selecting the first terminal device from the first terminal device and the second terminal device if the first terminal device further satisfies a third condition; The third condition is: The scheduling priority of the first terminal device is higher than the scheduling priority of the second terminal device; or The strength of interference of the first terminal device with respect to the neighboring cell is greater than the strength of interference of the second terminal device with respect to the neighboring cell; The method of claim 5 , comprising:

7. The step of selecting the first terminal device from the first terminal device and the second terminal device includes: determining a corresponding first transmission power reduction amount based on a first MCS of the first terminal device, and determining a corresponding second transmission power reduction amount based on a first MCS of the second terminal device; selecting the first terminal device from the first terminal device and the second terminal device when the first transmission power reduction amount is greater than the second transmission power reduction amount; Including, Before performing downlink data transmission with the first terminal device based on second downlink transmission parameters, the method further comprises: The method of claim 5 , further comprising the step of decreasing a transmission power of the first terminal device based on the first transmission power decrease amount.

8. Before performing downlink data transmission with the first terminal device based on second downlink transmission parameters, the method further comprises: The method according to any one of claims 1 to 6, further comprising the step of reducing the transmission power of the first terminal device.

9. 9. The method of claim 1, wherein the first downlink transmission parameters further include a first modulation and coding scheme (MCS), and the second downlink transmission parameters further include a second MCS, and the first MCS is equal to the second MCS.

10. 1. A communications device, comprising: a processing unit and a transceiver unit, the processing unit: determining first downlink transmission parameters of the first terminal device based on a state of a downlink channel of the first terminal device, the first downlink transmission parameters including a first rank; Determine a first number of resource blocks (RBs) occupied by downlink data of the first terminal device based on the first downlink transmission parameters; determining a first number of remaining RBs based on the number of allocatable RBs and the first number of RBs; When the first terminal device satisfies at least a first condition, perform downlink data transmission with the first terminal device based on second downlink transmission parameters using the transceiver unit, the second downlink transmission parameters including a second rank, the number of spatial multiplexing streams indicated by the second rank being less than the number of spatial multiplexing streams indicated by the first rank, and the first condition including that the first remaining number of RBs supports a reduction from the first rank of the first terminal device to the second rank. Communication equipment.

11. the first terminal device is one of at least two terminal devices based on single-user scheduling, and the at least two terminal devices further include a second terminal device, wherein the numbers of both spatial multiplexing streams determined based on the state of the downlink channel of the first terminal device and the second terminal device are greater than 1, the first number of remaining RBs of the first terminal device supports a reduction from the first rank to the second rank of the first terminal device, and the second number of remaining RBs of the second terminal device supports a reduction from the third rank to the fourth rank of the second terminal device, but when the reduction from the first rank to the second rank of the first terminal device is performed, the first number of remaining RBs does not support a reduction from the third rank to the fourth rank of the second terminal device, the second number of remaining RBs is determined based on the number of allocatable RBs and the number of RBs occupied by downlink data of the second terminal device, and the third rank is determined based on the state of the downlink channel of the second terminal device; The processing unit specifically includes: selecting the first terminal device from the first terminal device and the second terminal device; performing downlink data transmission with the first terminal device based on the second downlink transmission parameters using the transceiver unit; The communication device according to claim 10, configured to:

12. The processing unit specifically includes: configured to select the first terminal device from the first terminal device and the second terminal device if the first terminal device further satisfies a second condition; The communication device according to claim 11 , wherein the second condition includes that the strength of interference of the first terminal device with respect to a neighboring cell is greater than the strength of interference of the second terminal device with respect to a neighboring cell.

13. 11. The communications device of claim 10, wherein the first terminal device is a terminal device in a first multi-user group of at least two multi-user groups based on multi-user scheduling, the at least two multi-user groups further including a second multi-user group, the number of allocatable RBs is a total number of RBs occupied by downlink data of terminal devices in the second multi-user group, and the total number of RBs occupied by the downlink data of the terminal devices in the second multi-user group is equal to or greater than a total number of RBs occupied by downlink data of terminal devices in each of the at least two multi-user groups.

14. the first multi-user group further includes a second terminal device, and the numbers of both spatial multiplexing streams determined based on the state of the downlink channel of the first terminal device and the second terminal device are greater than 1; the first number of remaining RBs of the first terminal device supports a reduction from the first rank to the second rank of the first terminal device, and the second number of remaining RBs of the second terminal device supports a reduction from the third rank to the fourth rank of the second terminal device, but when the reduction from the first rank to the second rank of the first terminal device is performed, the first number of remaining RBs does not support a reduction from the third rank to the fourth rank of the second terminal device; the second number of remaining RBs of the second terminal device is determined based on the number of allocatable RBs and the number of RBs occupied by downlink data of the second terminal device, and the third rank is determined based on the state of the downlink channel of the second terminal device; The processing unit specifically includes: selecting the first terminal device from the first terminal device and the second terminal device; performing downlink data transmission with the first terminal device based on the second downlink transmission parameters using the transceiver unit; The communication device according to claim 13, configured to:

15. The processing unit specifically includes: and configured to select the first terminal device from the first terminal device and the second terminal device if the first terminal device further satisfies a third condition; The third condition is: The scheduling priority of the first terminal device is higher than the scheduling priority of the second terminal device; or The strength of interference of the first terminal device with respect to the neighboring cell is greater than the strength of interference of the second terminal device with respect to the neighboring cell; 15. The communication device of claim 14, comprising:

16. The processing unit specifically includes: determining a corresponding first transmission power reduction amount based on a first MCS of the first terminal device, and determining a corresponding second transmission power reduction amount based on the first MCS of the second terminal device; selecting the first terminal device from the first terminal device and the second terminal device when the first transmission power reduction amount is greater than the second transmission power reduction amount; It is configured as follows:

15. The communication device of claim 14, wherein the processing unit is further configured to reduce the transmission power of the transceiver unit for the first terminal device based on the first transmission power reduction amount before downlink data transmission with the first terminal device is performed based on the second downlink transmission parameter.

17. The communication device of any one of claims 10 to 15, wherein the processing unit is further configured to reduce the transmission power of the transceiver unit for the first terminal device before downlink data transmission with the first terminal device is performed based on the second downlink transmission parameters.

18. 18. The communication device of claim 10, wherein the first downlink transmission parameters further include a first modulation and coding scheme (MCS), and the second downlink transmission parameters further include a second MCS, and the first MCS is equal to the second MCS.

19. A communications device comprising one or more processors, wherein execution of one or more computer program instructions by said one or more processors enables said communications device to perform a method according to any one of claims 1 to 9.

20. 10. A computer-readable storage medium, the computer-readable storage medium comprising a computer program, the computer program being configured to enable a communication device to perform a method according to any one of claims 1 to 9 when executed on the communication device.

21. A chip coupled to a memory and configured to read and execute program instructions stored in the memory to perform the method of any one of claims 1 to 9.

22. A computer program product, which when called by a computer, enables the computer to carry out the method according to any one of claims 1 to 9.

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