Nodes, user devices, communication systems, and communication methods

Abstract

To suppress gain reduction and SINR reduction due to inter-panel interference in spatial multiplexing of multiple pushes to multiple transmission / reception points. [Solution] The node is a node that connects to one of several transmit / receive points in an environment where they do not perform cooperative control with each other, and transmits an RRC message containing information indicating that there are multiple transmit / receive points, receives a reference signal via the first transmit / receive point, multiplexes and transmits information indicating a precoding index corresponding to a first precoding matrix calculated using the reference signal and a codebook to a first physical downlink control channel transmitted from the first transmit / receive point, and receives a physical uplink sharing channel transmitted using a precoding matrix formed by combining the first precoding matrix and the second precoding matrix.

Description

[Technical Field]

[0001] The present invention relates to a node, user equipment, communication system, and communication method. [Background technology]

[0002] In the 5th generation (5G) standard NR (New Radio) (Non-Patent Literature 1), formulated by the 3rd Generation Partnership Project (3GPP (registered trademark; hereinafter the same)), a standardization project for mobile communication systems, there is room for improvement in the following two points regarding spatial multiplexing transmission of a physical uplink sharing channel (PUSCH) using multiple transmission and reception points (Multi-TRP) (hereinafter referred to as "SDM transmission mode").

[0003] The first issue is that the user equipment (UE) antenna port is divided into two panels, and two different pushes are associated with each panel for transmission. When transmitting using a divided antenna port, the gain is reduced by 3dB compared to transmitting using the entire antenna port, which is disadvantageous in securing a communication area.

[0004] The second point is that PUSCH's SDM transmission mode using Multi-TRP does not have precoding that takes into account inter-panel interference (inter-stream interference to multiple TRPs). Therefore, even with spatial multiplexing, inter-panel interference is significant, and it is thought that the Signal-to-Interference-plus-Noise Ratio (SINR) cannot be ensured. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] 3GPP Technical Specification: TR 21.916 V16.2.0 (2022-06) [Non-Patent Document 2] “A Review of Codebooks for CSI Feedback in 5G New Radio and Beyond,” [online], Ziao Qin, Haifan Yin, February 18, 2023, Internet <URL: https: / / arxiv.org / abs / 2302.09222> [Overview of the Initiative]

[0006] A node according to the first embodiment is a node that connects to one of a plurality of transmit / receive points in an environment where they do not perform cooperative control with each other, and transmits an RRC message to a user device that includes information indicating that there are multiple transmit / receive points, and the user device that receives the RRC message transmits to the first transmit / receive point among the plurality of transmit / receive points First The first physical downlink control channel receives a reference signal and transmits it from the first transmission / reception point to the user device. First Information indicating the precoding index corresponding to the first precoding matrix calculated using the reference signal and the codebook is multiplexed and transmitted to the user device via the first transmit / receive point. The user device receives a physical uplink shared channel transmitted using a precoding matrix formed by combining the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel transmitted from the second transmit / receive point among the plurality of transmit / receive points to the user device. The second precoding matrix is ​​a precoding matrix calculated using the second reference signal and codebook transmitted by the user device to the second transmit / receive point. .

[0007] The user device according to the second embodiment is a user device that connects to each of a plurality of transmit / receive points in an environment in which they do not perform cooperative control with each other, and receives an RRC message containing information indicating that there are a plurality of transmit / receive points from at least one of the plurality of transmit / receive points, transmits a reference signal to each of the plurality of transmit / receive points on a single panel, and receives a first physical downlink control channel from the first transmit / receive point in which information indicating a precoding index corresponding to a first precoding matrix calculated using the first reference signal transmitted to the first transmit / receive point among the plurality of transmit / receive points and a codebook is multiplexed from the reference signal, and The system receives a second physical downlink control channel from the second transmission / reception point, which is multiplexed with information indicating a precoding index corresponding to a second precoding matrix calculated using a second reference signal and a codebook transmitted to the second transmission / reception point among the plurality of transmission / reception points. The system then transmits a first physical uplink sharing channel and a second physical uplink sharing channel to the first transmission / reception point and the second transmission / reception point, respectively, using a precoding matrix obtained by combining the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel.

[0008] The third embodiment of the communication system comprises a first node connected to a first transmit / receive point among a plurality of transmit / receive points in an environment in which they do not perform cooperative control with each other, a second node connected to a second transmit / receive point among the plurality of transmit / receive points, and user devices connected to each of the plurality of transmit / receive points, wherein the first node transmits an RRC message to the user device including information indicating that there are a plurality of transmit / receive points, receives a first reference signal from the user device that received the RRC message via the first transmit / receive point, multiplexes information indicating a precoding index corresponding to a first precoding matrix calculated using the first reference signal and a codebook onto a first physical downlink control channel transmitted from the first transmit / receive point to the user device, and transmits it to the user device via the first transmit / receive point, and the second node transmits an RRC message to the user device including information indicating that there are a plurality of transmit / receive points, and the RRC message The user device receives a second reference signal from the user device via the second transmit / receive point, and transmits to the user device via the second transmit / receive point a second physical downlink control channel that the second transmit / receive point transmits to the user device, multiplexing information indicating a precoding index corresponding to a second precoding matrix calculated using the second reference signal and the codebook, the user device receives an RRC message from at least one of the multiple transmit / receive points that includes information indicating that there are multiple transmit / receive points, transmits a reference signal to each of the multiple transmit / receive points in a single panel, receives the first physical downlink control channel from the first transmit / receive point with multiplexed information indicating a precoding index corresponding to the first precoding matrix, and receives the second physical downlink control channel from the second transmit / receive point with multiplexed information indicating a precoding index corresponding to the second precoding matrix.The first and second physical uplink sharing channels are transmitted to the first and second transmission / reception points, respectively, using a precoding matrix obtained by combining the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel. The first node receives the first physical uplink sharing channel transmitted using the precoding matrix obtained by combining the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel from the user device. The second node receives the second physical uplink sharing channel transmitted using the precoding matrix obtained by combining the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel from the user device.

[0009] A fourth aspect of the communication method is a communication method used by a node connected to one of a plurality of transmitting and receiving points in an environment where they do not perform cooperative control with each other, the method comprising the steps of: transmitting an RRC message containing information indicating that there are multiple transmitting and receiving points to a user device; and transmitting from the user device that received the RRC message to the first transmitting and receiving point among the plurality of transmitting and receiving points First The steps include receiving a reference signal and transmitting a first physical downlink control channel from the first transmission / reception point to the user device, FirstThe process includes: multiplexing information indicating a precoding index corresponding to a first precoding matrix calculated using a reference signal and a codebook, and transmitting it to the user device via the first transmit / receive point; and receiving a physical uplink shared channel transmitted from the user device using a precoding matrix formed by combining the first precoding matrix specified by the first physical downlink control channel and the second precoding matrix specified by the second physical downlink control channel transmitted from the second transmit / receive point among the plurality of transmit / receive points to the user device. The second precoding matrix is ​​a precoding matrix calculated using the second reference signal and codebook transmitted by the user device to the second transmit / receive point. .

[0010] A communication method according to the fifth aspect is a communication method used in a user device connected to each of a plurality of transmit / receive points in an environment in which they do not perform cooperative control with each other, comprising the steps of: receiving an RRC message containing information indicating that there are a plurality of transmit / receive points from at least one of the plurality of transmit / receive points; transmitting a reference signal to each of the plurality of transmit / receive points on a single panel; receiving a first physical downlink control channel from the first transmit / receive point in which information indicating a precoding index corresponding to a first precoding matrix calculated using a first reference signal transmitted to the first transmit / receive point among the plurality of transmit / receive points and a codebook is multiplexed from the reference signal; and the reference signal The process includes the steps of: receiving from the second physical downlink control channel a second physical downlink control channel from which information indicating a precoding index corresponding to a second precoding matrix calculated using a second reference signal and a codebook among the plurality of transmit / receive points transmitted to the second transmit / receive point; and transmitting a first physical uplink sharing channel and a second physical uplink sharing channel to the first transmit / receive point and the second transmit / receive point, respectively, using a precoding matrix obtained by combining the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel. [Brief explanation of the drawing]

[0011] [Figure 1] This is a diagram showing an example configuration of a mobile communication system according to the embodiment. [Figure 2] This figure shows an example of the protocol stack configuration for a U-plane wireless interface that handles data. [Figure 3] This diagram shows an example of a protocol stack configuration for a C-plane wireless interface that handles signaling (control signals). [Figure 4] This figure shows a typical procedure for sending a PUSCH command using a Codebook type in an ideal BH environment. [Figure 5] This figure shows a typical procedure for sending a PUSCH command using a Codebook type in an ideal BH environment. [Figure 6] This figure shows an example of how information indicating the precoding index for the first TRP and information indicating the precoding index for the second TRP are multiplexed into a single PDCCH. [Figure 7] This figure shows a general procedure for sending a PUSCH using a Codebook type in a non-ideal BH environment. [Figure 8] This figure shows a general procedure for sending a PUSCH using a Codebook type in a non-ideal BH environment. [Figure 9] This figure shows an example of how information indicating a precoding index for the first TRP according to the first embodiment is multiplexed on PDCCH#1, and information indicating a precoding index for the second TRP is multiplexed on PDCCH#2. [Figure 10] This figure shows an example configuration of a UE (User Equipment) according to the embodiment. [Figure 11] This figure shows an example of a node configuration according to the embodiment. [Figure 12] This figure shows an example of system operation according to the first embodiment. [Figure 13] This figure shows an example of system operation according to the first embodiment. [Figure 14] This figure shows an example of a unique channel formed by the SVD according to the first embodiment. [Figure 15] This figure shows an example of scheduling when transmitting with a higher priority for PUSCH#1 than for PUSCH#2 according to the first embodiment. [Figure 16] This figure shows an example of scheduling when transmitting data while keeping the priority of PUSCH#1 and PUSCH#2 as similar as possible according to the first embodiment. [Figure 17] This figure shows an example of a method for multiplexing the SRI, RI, and TPMI, which are integrated by the first TRP and the second TRP, into a single PDCCH in the case of single-panel transmission according to the first embodiment. [Figure 18] This figure shows an example of a method for multiplexing the SRI, RI, and TPMI, which are integrated by the first TRP and the second TRP, into a single PDCCH in the case of single-panel transmission according to the first embodiment. [Figure 19] This figure shows an example of a method for multiplexing the SRI, RI, and TPMI, which are integrated by the first TRP and the second TRP, into a single PDCCH in the case of single-panel transmission according to the first embodiment. [Figure 20] This figure shows an example of system operation according to the second embodiment. [Figure 21] This figure shows an example of system operation according to the second embodiment. [Figure 22] This figure shows an example of system operation according to a modified version of the second embodiment. [Figure 23] This figure shows an example of system operation according to a modified version of the second embodiment. [Figure 24] This is a conceptual diagram of channel information exchange according to a modified example of the second embodiment. [Figure 25] This figure shows a timing chart relating to the exchange of channel information according to a modified example of the second embodiment. [Figure 26] This figure shows the calculation of the precoding matrix according to a modified example of the second embodiment. [Figure 27] This figure shows an example of system operation according to the third embodiment. [Figure 28] This figure shows an example of system operation according to the third embodiment. [Figure 29] This figure shows the deformation of the propagation channel by precoding weights in a hybrid type of Codebook type and Non-codebook type according to the third embodiment. [Figure 30] This figure shows the deformation of the propagation channel by precoding weights in a hybrid type of Codebook type and Non-codebook type according to the third embodiment. [Figure 31] This figure shows an overview of SRS signal transmission according to the third embodiment, and signal processing for SRS signal transmission. [Figure 32] This figure shows an overview of the transmission of a PUSCH signal according to the third embodiment, and the signal processing for the transmission of the PUSCH signal. [Modes for carrying out the invention]

[0012] In the following, a mobile communication system according to an embodiment will be described with reference to the drawings. In the drawings, identical or similar parts are denoted by the same or similar reference numerals.

[0013] (1) First Embodiment A first embodiment will be described with reference to Figures 1 to 7.

[0014] (1.1) Example of system configuration Figure 1 shows an example configuration of a mobile communication system according to an embodiment. The mobile communication system according to the embodiment is a system compliant with the 3GPP standard. For example, the mobile communication system according to the embodiment may be a fifth-generation (5G) system or a sixth-generation (6G) system.

[0015] The mobile communication system comprises a network (NW) 1 and a user device (UE) 100. The UE 100 is a mobile communication device that performs wireless communication with the NW 1. The UE 100 may be any device used by a user, such as a mobile phone terminal (including a smartphone) or tablet terminal, a notebook PC (Personal Computer), a communication module (including a communication card or chipset), a sensor or a device attached to a sensor, a vehicle or a device attached to a vehicle (Vehicle UE), or an aircraft or a device attached to an aircraft (Aerial UE).

[0016] NW1 includes the Radio Access Network (RAN) 10 and the Core Network (CN) 20. When the mobile communication system is a 5th Generation System (5GS), RAN 10 is referred to as NG-RAN (Next Generation Radio Access Network) and CN 20 is referred to as 5GC (5G Core Network).

[0017] RAN10 includes multiple nodes 200 (nodes 200a to 200c in the illustrated example). The nodes 200 are interconnected via internode interfaces. Nodes 200 are also referred to as base stations. Nodes 200 consist of a CU (Central Unit), a DU (Distributed Unit), and a RU (Radio Unit) (i.e., functionally separated), and the two units may be connected by a fronthaul interface. If the mobile communication system is 5GS, the nodes 200 are referred to as gNBs, the internode interfaces as Xn interfaces, and the fronthaul interfaces as F1 interfaces.

[0018] Each node 200 manages one or more cells. Node 200 performs wireless communication with UE100s that have established a connection with its own cell. Each node 200 has wireless resource management (RRM) functions, user data routing functions (also simply referred to as "data"), and measurement and control functions for mobility control and scheduling. The term "cell" is used to indicate the smallest unit of a wireless communication area. The term "cell" is also used to indicate the function or resource that performs wireless communication with the UE100. One cell belongs to one carrier frequency (also simply referred to as "frequency").

[0019] CN20 includes CN device 300. CN device 300 may include a C-plane device corresponding to the control plane (C-plane) and a U-plane device corresponding to the user plane (U-plane). The C-plane device performs various mobility controls and paging for UE100. The C-plane device communicates with UE100 using NAS (Non-Access Stratum) signaling. The U-plane device controls data transfer. When the mobile communication system is 5GS, the C-plane device is called AMF (Access and Mobility Management Function), the U-plane device is called UPF (User Plane Function), and the interface between node 200 and CN device 300 is called the NG interface.

[0020] Figure 2 shows an example of the protocol stack configuration for a U-plane radio interface that handles data.

[0021] A U-plane radio interface protocol, for example, includes a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an SDAP (Service Data Adaptation Protocol) layer.

[0022] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of Node 200 via a physical channel. The PHY layer of UE100 receives downlink control information (DCI) transmitted from Node 200 over the physical downlink control channel (PDCCH). Specifically, UE100 performs blind decoding of the PDCCH using a Radio Network Temporary Identifier (RNTI) and acquires the successfully decoded DCI as the DCI addressed to its own UE. The DCI transmitted from Node 200 has a CRC parity bit added that has been scrambled by the RNTI.

[0023] The MAC layer performs data priority control and retransmission processing using Hybrid ARQ (HARQ). Data and control information are transmitted between the MAC layer of UE100 and the MAC layer of Node 200 via the transport channel. The MAC layer of Node 200 includes a scheduler. The scheduler determines the transport format for the up and down links (transport block size, modulation and coding scheme (MCS)) and the resources to be allocated to UE100.

[0024] The RLC layer transmits data to the receiving RLC layer by utilizing the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of UE100 and the RLC layer of Node 200 via a logical channel.

[0025] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0026] The SDAP layer maps IP flows, which are the units for QoS control performed by CN20, to wireless bearers, which are the units for QoS control performed by AS (Access Stratum). Note that if the RAN is connected to the EPC, SDAP may not be necessary.

[0027] Figure 3 shows an example of the protocol stack configuration for a C-plane wireless interface that handles signaling (control signals).

[0028] The protocol stack of the C-plane radio interface, for example, includes an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer instead of the SDAP layer shown in Figure 2.

[0029] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of Node 200. The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re-establishment, and release of the radio bearer. If there is a connection (RRC connection) between the RRC of UE100 and the RRC of Node 200, UE100 is in the RRC connected state. If there is no connection (RRC connection) between the RRC of UE100 and the RRC of Node 200, UE100 is in the RRC idle state. If the connection between the RRC of UE100 and the RRC of Node 200 is suspended, UE100 is in the RRC inactive state.

[0030] The NAS layer (also simply referred to as "NAS"), located above the RRC layer, handles session management and mobility management, among other things. NAS signaling is transmitted between the NAS layer of the UE100 and the NAS layer of the CN device 300. The UE100 also has an application layer in addition to the wireless interface protocol. Furthermore, the layer below the NAS layer is called the AS layer (also simply referred to as "AS").

[0031] 3GPP considers two types of multi-transmission and reception point (Multi-TRP) transmission environments: ideal backhaul (BH) and non-ideal backhaul (Non-ideal BH). In an ideal backhaul, coordination is possible between multiple TRPs. Therefore, in an ideal backhaul, the postcoding node can spatially separate multiple physical uplink shared channels (PUSCHs) transmitted through each of the multiple TRPs. On the other hand, in a non-ideal backhaul, coordination does not occur between multiple TRPs, making coordinated postcoding between multiple TRPs impossible. Therefore, in a non-ideal backhaul, it is necessary to suppress inter-stream interference during precoding. Below, we will first describe the general procedures for transmitting PUSCHs using the Codebook type in both ideal and non-ideal backhaul environments.

[0032] Figures 4 and 5 illustrate a general procedure for transmitting a PUSCH using a Codebook type in an ideal BH environment. In the illustrated procedure, UE100 and DU260a communicate via the first TRP270a or the second TRP270b. The first TRP270a and the second TRP270b can cooperate. Note that DU260a and the first TRP270a are, for example, the DU and RU that constitute node 200a shown in Figure 1. DU260b and the second TRP270b are, for example, the DU and RU that constitute node 200b shown in Figure 1. In the diagrams, the first TRP270a is also referred to as TRP#1, and the second TRP270b is also referred to as TRP#2.

[0033] In step S110, DU260a transmits PUSCH configuration information to UE100 via the first TRP270a or the second TRP270b. UE100 receives the PUSCH configuration information. The PUSCH configuration information includes configuration information for PUSCH#1 (PUSCH-Config#1) and configuration information for PUSCH#2 (PUSCH-Config#2). PUSCH#1 is the PUSCH transmitted via the first TRP270a. PUSCH#2 is the PUSCH transmitted via the second TRP270b.

[0034] In step S120, DU260a transmits the SRS (Sounding Reference Signal) resource settings to UE100 via the first TRP270a or the second TRP270b. UE100 receives the SRS resource settings. The SRS resource settings include the SRS#1 resource settings and the SRS#2 resource settings. SRS#1 is the SRS transmitted via the first TRP270a. SRS#2 is the SRS transmitted via the second TRP270b.

[0035] In step S130, UE100 transmits SRS#1 to the first TRP270a using one of the panels in which the antenna port is divided into two. In other words, UE100 transmits SRS#1 via multi-panel transmission.

[0036] In step S140, the first TRP270a transmits SRS#1, which it received from UE100, to DU260a. DU260a receives SRS#1.

[0037] In step S150, UE100 transmits SRS#2 to the second TRP270b using one of the panels with two divided antenna ports. In other words, UE100 transmits SRS#2 via multi-panel transmission.

[0038] In step S160, the second TRP270b transmits SRS#2, which it received from UE100, to DU260a. DU260a receives SRS#2.

[0039] Note that the processes in steps S130 and S140 and the processes in steps S150 and S160 are executed in parallel. Furthermore, the SRS resources configured by the resource settings received in step S120 are used for these SRS transmissions. In addition, one SRS antenna port is configured for each SRS resource.

[0040] In step S170, DU260a performs coordinated scheduling of PUSCH between the first TRP270a and the second TRP270b.

[0041] In step S180, DU260a sends the PUSCH resource settings to UE100 via the first TRP270a or the second TRP270b. UE100 receives the PUSCH resource settings, which include the PUSCH#1 resource settings and the PUSCH#2 resource settings.

[0042] In step S190, DU260a calculates a precoding matrix (referred to as precoding matrix #1) corresponding to the channel between UE100 and the first TRP270a. DU260a also calculates a precoding matrix (referred to as precoding matrix #2) corresponding to the channel between UE100 and the second TRP270b.

[0043] Here, DU260a performs MIMO (multiple-input and multiple-output) channel estimation for the channel between UE100 and 1TRP270a based on SRS#1 received by 1TRP270a, and calculates a precoding matrix (precoding weights). DU260a also performs MIMO channel estimation for the channel between UE100 and 2TRP270b based on SRS#2 received by 2TRP270b, and calculates a precoding matrix (precoding weights). In an ideal BH environment, channel information for precoding and postcoding is shared between 1TRP270a and 2TRP270b.

[0044] In step S1100, DU260a determines the SRI (SRS Resource Indicator), RI (Rank Indicator), and TPMI (Transmitted Matrix Precoding Indicator) for the first TRP270a. The SRI, RI, and TPMI for the first TRP270a correspond to the precoder used for transmitting PUSCH#1. DU260a also determines the SRI, RI, and TPMI for the second TRP270b. The SRI, RI, and TPMI for the second TRP270b correspond to the precoder used for transmitting PUSCH#2. Here, the SRI, RI, and TPMI for the first TRP270a and the SRI, RI, and TPMI for the second TRP270b are determined independently of each other.

[0045] Separate codebooks are used to determine the SRI, RI, and TPMI for the first TRP270a and for the second TRP270b. The size of these codebooks corresponds to the number of antenna ports on the UE100, which are divided into two sections according to multi-panel transmission. Therefore, each column of precoding matrix #1 and precoding matrix #2 is half the size of the number of antenna ports on the UE100.

[0046] In step S1110, DU260a multiplexes the SRI, RI, and TPMI for the first TRP270a and the SRI, RI, and TPMI for the second TRP270b into the PDCCH of the first TRP270a and transmits it to UE100. Here, the PDCCH of the TRP is the PDCCH transmitted to UE100 via that TRP. Therefore, DU260a transmits a single PDCCH, which is multiplexed with the SRI, RI, and TPMI for the first TRP270a and the SRI, RI, and TPMI for the second TRP270b, to UE100 via the first TRP270a. UE100 receives the PDCCH. In addition, in the drawings, the SRI, RI, and TPMI for the first TRP270a are also referred to as "(SRI,RI,TPMI)#1", and the SRI, RI, and TPMI for the second TRP270b are also referred to as "(SRI,RI,TPMI)#2".

[0047] As described above, the PDCCH of the first TRP270a is multiplexed with the SRI, RI, and TPMI for the first TRP270a and the SRI, RI, and TPMI for the second TRP270b. SRI, RI, and TPMI are examples of information indicating the precoding index. In other words, the information indicating the precoding index for the first TRP270a and the information indicating the precoding index for the second TRP270b are multiplexed in a single PDCCH. Furthermore, DU260a may multiplex the SRI, RI, and TPMI for the first TRP270a and the SRI, RI, and TPMI for the second TRP270b on the PDCCH of the second TRP270b and transmit them to UE100.

[0048] Figure 6 shows an example of how information indicating the precoding index for the first TRP270a ((SRI,RI,TPMI)#1) and information indicating the precoding index for the second TRP270b ((SRI,RI,TPMI)#2) are multiplexed onto a single PDCCH. In this figure, the DCI transmitted on the PDCCH contains multiplexed information indicating these precoding indices.

[0049] In step S1120, UE100 performs precoding of PUSCH#1 based on the SRI, RI, and TPMI for the first TRP270a.

[0050] In step S1130, UE100 transmits the precoded PUSCH#1 to DU260a via the first TRP270a. Here, UE100 transmits PUSCH#1 to DU260a via the first TRP270a using one of the panels in which the antenna port is divided into two. DU260a receives PUSCH#1.

[0051] In step S1140, UE100 performs precoding of PUSCH#2 based on the SRI, RI, and TPMI for the second TRP270b.

[0052] In step S1150, UE100 transmits the precoded PUSCH#2 to DU260a via the second TRP270b. Here, UE100 transmits PUSCH#2 to DU260a via the second TRP270b using one of the panels in which the antenna port is divided into two. DU260a receives PUSCH#2.

[0053] Here, the precoding of PUSCH#1 in step S1120 and the precoding of PUSCH#2 in step S1140 are performed independently of each other. Note that the processes in steps S1120 and S1130 and the processes in steps S1140 and S1150 may be performed in reverse order or in parallel.

[0054] In step S1160, DU260a performs post-coding of PUSCH#1.

[0055] In step S1170, DU260a performs post-coding of PUSCH#2.

[0056] Here, the postcoding of PUSCH#1 in step S1160 and the postcoding of PUSCH#2 in step S1170 are performed independently of each other. Note that the processing in step S1160 and the processing in step S1170 may be performed in reverse order or in parallel.

[0057] Figures 7 and 8 illustrate a typical procedure for transmitting a PUSCH signal using a Codebook type in a non-ideal BH environment. In the illustrated procedure, UE100 and DU260a communicate via the first TRP270a. UE100 and DU260b communicate via the second TRP270b. The first TRP270a and the second TRP270b do not coordinate with each other. Note that the processes in steps S250 and S270, and steps S2150 and S2170 are the same as the processes in steps S130 and S150, and steps S1120 and S1140 in Figure 4, so their explanation will be omitted.

[0058] In step S210, DU260a transmits the PUSCH#1 configuration information to UE100 via the first TRP270a. UE100 receives the PUSCH#1 configuration information.

[0059] In step S220, DU260b transmits the PUSCH#2 configuration information to UE100 via the second TRP270b. UE100 receives the PUSCH#2 configuration information.

[0060] In step S230, DU260a transmits the resource settings for SRS#1 to UE100 via the first TRP270a. UE100 receives the resource settings for SRS#1.

[0061] In step S240, DU260b sends the resource settings for SRS#2 to UE100 via the second TRP270b. UE100 receives the resource settings for SRS#2.

[0062] In step S260, the first TRP270a transmits SRS#1, which it received from UE100, to DU260a. DU260a receives SRS#1.

[0063] In step S280, the second TRP270b transmits SRS#2, which it received from UE100, to DU260b. DU260b receives SRS#2.

[0064] In step S290, DU260a calculates a precoding matrix (denoted as precoding matrix #1) corresponding to the channel between UE100 and the first TRP270a. Here, DU260a performs MIMO channel estimation for the channel between UE100 and the first TRP270a based on SRS#1 received by the first TRP270a, and calculates a precoding matrix (precoding weights).

[0065] In step S2100, DU260b calculates a precoding matrix (denoted as precoding matrix #2) corresponding to the channel between UE100 and the second TRP270b. Here, DU260b performs MIMO channel estimation for the channel between UE100 and the second TRP270b based on SRS#2 received by the second TRP270b, and calculates a precoding matrix (precoding weight).

[0066] In step S2110, DU260a determines the SRI, RI, and TPMI for the first TRP270a. The codebook used to determine the SRI, RI, and TPMI for the first TRP270a is sized to correspond to the number of antenna ports on the UE100, which are divided into two groups according to multi-panel transmission. Therefore, the columns of precoding matrix #1 are half the size of the number of antenna ports on the UE100.

[0067] In step S2120, DU260b determines the SRI, RI, and TPMI for the second TRP270b. The type of codebook used to determine the SRI, RI, and TPMI for the second TRP270b is the same as the codebook used in step S2110.

[0068] Note that the processes in steps S290 and S2110 and the processes in steps S2100 and S2120 are executed in parallel.

[0069] In step S2130, DU260a multiplexes the SRI, RI, and TPMI for the first TRP270a onto PDCCH#1 of the first TRP270a and transmits it to UE100. DU260a transmits PDCCH#1 to UE100 via the first TRP270a. UE100 receives PDCCH#1.

[0070] In step S2140, DU260b multiplexes the SRI, RI, and TPMI for the second TRP270b onto PDCCH#2 of the second TRP270b and transmits it to UE100. DU260b transmits the PDCCH#2 to UE100 via the second TRP270b. UE100 receives the PDCCH#2.

[0071] Figure 9 shows an example of how information indicating the precoding index for the first TRP270a is multiplexed on PDCCH#1, and information indicating the precoding index for the second TRP270b is multiplexed on PDCCH#2. In this figure, the DCI transmitted on PDCCH#1 contains information indicating the precoding index for the first TRP270a, and the DCI transmitted on PDCCH#2 contains information indicating the precoding index for the second TRP270b.

[0072] In step S2160, UE100 transmits the precoded PUSCH#1 to DU260a via the first TRP270a. Here, UE100 transmits PUSCH#1 to DU260a via the first TRP270a using one of the panels in which the antenna port is divided into two. DU260a receives PUSCH#1.

[0073] In step S2180, UE100 transmits the precoded PUSCH#2 to DU260b via the second TRP270b. Here, UE100 transmits PUSCH#2 to DU260b via the second TRP270b using one of the panels in which the antenna port is divided into two. DU260b receives PUSCH#2.

[0074] In step S2190, DU260a performs post-coding of PUSCH#1.

[0075] In step S2200, DU260b performs post-coding of PUSCH#2.

[0076] According to the procedures described above for both ideal and non-ideal BH environments, the antenna port is divided into two panels, and two different PUSCH signals are associated with each panel for transmission. Transmission using a divided antenna port results in a 3dB decrease in gain compared to transmission using all antenna ports, which is disadvantageous in securing a communication area. Furthermore, according to these procedures, the SDM transmission mode of PUSCH using Multi-TRP does not take into account inter-panel interference (inter-stream interference to multiple TRPs) in the precoding. Therefore, even with spatial multiplexing, inter-panel interference is likely to be significant, and it is thought that a Signal-to-Interference-plus-Noise Ratio (SINR) cannot be secured.

[0077] The embodiments described below describe a single-panel MIMO transmission method in the SDM transmission mode of the uplink PUSCH using Multi-TRP, which employs precoding that takes into account inter-stream interference to multiple TRPs.

[0078] (1.2) Example of user device configuration Figure 10 shows an example configuration of UE100 (user device) according to an embodiment.

[0079] UE100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 constitute a wireless communication unit 140 that performs wireless communication with the node 200.

[0080] The receiving unit 110 performs various types of reception under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 130. The transmitting unit 120 performs various types of transmission under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmitted signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0081] The control unit 130 performs various control and processing operations on the UE 100. The operation of the UE 100 described above and below may be controlled by the control unit 130. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation, demodulation, encoding, and decoding of baseband signals. The CPU executes programs stored in memory and performs various processing operations.

[0082] The UE100 configured in this way is a user device that connects to multiple transmit / receive points (in this embodiment, the first TRP270a and the second TRP270b) that can be controlled in coordination with each other. The receiving unit 110 receives an RRC message from at least one of the multiple transmit / receive points that contains information indicating that there are multiple transmit / receive points. The transmitting unit 120 transmits a reference signal to each of the multiple transmit / receive points on a single panel. The receiving unit 110 receives a PDCCH from either the first transmit / receive point or the second transmit / receive point of the multiple transmit / receive points, in which information indicating a precoding index corresponding to a single precoding matrix corresponding to both the channel between UE100 and the first transmit / receive point and the channel between UE100 and the second transmit / receive point is multiplexed. The control unit 130 calculates a precoder to be used for transmitting PUSCH based on the information indicating the precoding index multiplexed in the received PDCCH. The transmitting unit 120 transmits PUSCH to which the precoder has been applied.

[0083] As a result, the UE100 can perform spatial multiplexing of multiple pushers using all antenna ports, thus avoiding the loss of gain that occurs when antenna ports are divided. Furthermore, the UE100 suppresses the decrease in SINR caused by inter-panel interference associated with spatial multiplexing through a pre-coding configuration that suppresses interference between multiple pushers.

[0084] (1.3) Example of node configuration Figure 11 shows an example configuration of node 200 (base station, gNB) according to the embodiment.

[0085] Node 200 includes a transmitter 210, a receiver 220, a control unit 230, and a network communication unit 240. The transmitter 210 and receiver 220 constitute a wireless communication unit 250 that performs wireless communication with UE 100.

[0086] The transmitting unit 210 performs various types of transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna. The receiving unit 220 performs various types of receptions under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts the radio signal received by the antenna into a baseband signal (received signal) and outputs it to the control unit 230.

[0087] The control unit 230 performs various controls and processes at node 200. The operation of node 200 described above and below may be controlled by the control unit 230. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation, demodulation, encoding, and decoding of baseband signals. The CPU executes programs stored in memory and performs various processes.

[0088] The NW communication unit 240 is connected to an adjacent node via an inter-node interface. The NW communication unit 240 is connected to the CN device 300 via a node-CN interface.

[0089] The node 200 configured in this way is a node that connects to a plurality of transmit / receive points (in this embodiment, the first TRP 270a and the second TRP 270b) that can be controlled in coordination with each other. The transmitting unit 210 transmits an RRC message to the UE 100 that includes information indicating that there are multiple transmit / receive points. The receiving unit 220 receives a plurality of reference signals from the UE 100 that has received the RRC message, via each of the plurality of transmit / receive points. The transmitting unit 210 multiplexes information indicating a precoding index corresponding to a single precoding matrix corresponding to both the channel between the UE 100 and the first transmit / receive point and the channel between the UE 100 and the second transmit / receive point, and transmits it to the UE 100 in the PDCCH transmitted to the UE 100 from either the first transmit / receive point or the second transmit / receive point among the plurality of transmit / receive points.

[0090] This allows node 200 to perform spatial multiplexing of multiple pushers using all antenna ports on UE100, thus avoiding gain reduction caused by splitting antenna ports. Furthermore, node 200 suppresses the decrease in SINR due to inter-panel interference associated with spatial multiplexing by using a pre-coding configuration that suppresses interference between multiple pushers.

[0091] (1.4) System operation example Figures 12 and 13 show examples of system operation according to the first embodiment. The system operation according to the first embodiment is a method for transmitting PUSCH using a Codebook type in an ideal BH environment. Note that redundant explanations of operations similar to those in Figures 4 and 5 are omitted.

[0092] In step S310, DU260a transmits PUSCH configuration information to UE100 via the first TRP270a or the second TRP270b. UE100 receives the PUSCH configuration information. The PUSCH configuration information includes the configuration information for PUSCH#1 (PUSCH-Config#1), the configuration information for PUSCH#2 (PUSCH-Config#2), the parameters for the SDM transmission mode, and information indicating that there are multiple TRPs. The parameters for the SDM transmission mode may be referred to, for example, "SinglepanelSchemeSDM".

[0093] The parameters for the SDM transmission mode are information that allows the UE100 to perform spatial multiplexing transmission using multiple TRPs on the uplink in a single panel. Also, as mentioned above, the PUSCH setting information includes information indicating that there are multiple TRPs. Therefore, the DU260a sends an RRC message to the UE100 that includes information indicating that there are multiple TRPs. The multiple TRPs are the first TRP270a and the second TRP270b.

[0094] In step S320, DU260a transmits the SRS resource settings to UE100 via the first TRP270a or the second TRP270b. UE100 receives the SRS resource settings, which include the resource settings for SRS#1 and the resource settings for SRS#2.

[0095] In step S330, UE100 transmits SRS#1 to the first TRP270a and SRS#2 to the second TRP270b using all antenna ports. In other words, UE100 transmits SRS#1 and SRS#2 by single-panel transmission. Note that in the transmission of SRS#1 and SRS#2 by UE100 using all antenna ports, the transmission of SRS#1 and SRS#2 may or may not occur simultaneously.

[0096] In step S340, the first TRP270a transmits SRS#1, which it received from UE100, to DU260a. DU260a receives SRS#1.

[0097] In step S350, the second TRP270b transmits SRS#2, which it received from UE100, to DU260a. DU260a receives SRS#2.

[0098] In step S360, DU260a performs coordinated scheduling of PUSCH between the first TRP270a and the second TRP270b.

[0099] In step S370, DU260a sends the PUSCH resource settings to UE100 via the first TRP270a or the second TRP270b. UE100 receives the PUSCH resource settings, which include the PUSCH#1 resource settings and the PUSCH#2 resource settings.

[0100] In step S380, DU260a calculates a single precoding matrix corresponding to both the channel between UE100 and the first TRP270a, and the channel between UE100 and the second TRP270b. In the following description, the single precoding matrix corresponding to both the channel between UE100 and the first TRP270a, and the channel between UE100 and the second TRP270b, will also be referred to as the precoding matrix obtained by integrating the first TRP270a and the second TRP270b.

[0101] Here, DU260a performs MIMO (multiple-input and multiple-output) channel estimation based on SRS#1 received by the first TRP270a and SRS#2 received by the second TRP270b, corresponding to both the channel between UE100 and the first TRP270a and the channel between UE100 and the second TRP270b, and calculates a precoding matrix (precoding weights). In an ideal BH environment, channel information for precoding and postcoding is shared between the first TRP270a and the second TRP270b. DU260a calculates precoding weights based on Singular Value Decomposition (SVD).

[0102] In step S390, DU260a determines the SRI, RI, and TPMI corresponding to a single precoding matrix that corresponds to both the channel between UE100 and the first TRP270a, and the channel between UE100 and the second TRP270b. In the following description, the SRI, RI, and TPMI corresponding to the precoding matrix integrated by the first TRP270a and the second TRP270b will also be referred to as the integrated SRI, RI, and TPMI from the first TRP270a and the second TRP270b.

[0103] DU260a, in determining the SRI, RI, and TPMI integrated between the first TRP270a and the second TRP270b, applies the Downlink Type I (Codebook 1) codebook to Multi-TRP transmission as an example. However, the codebook used to determine the SRI, RI, and TPMI integrated between the first TRP270a and the second TRP270b may be a codebook other than Downlink Type I, as long as SVD transmission is possible.

[0104] Furthermore, DU260a determines the integrated SRI based on scheduling that takes into account the priorities of both PUSCH#1 and PUSCH#2. Details of how the integrated SRI is determined will be described later.

[0105] In step S3100, DU260a multiplexes the SRI, RI, and TPMI, which are integrated from the first TRP270a and the second TRP270b, onto the PDCCH of the first TRP270a and transmits it to UE100. UE100 receives the PDCCH. Alternatively, DU260a may multiplex the SRI, RI, and TPMI, which are integrated from the first TRP270a and the second TRP270b, onto the PDCCH of the second TRP270b and transmit it to UE100. Details on how to multiplex the SRI, RI, and TPMI integrated from the first TRP270a and second TRP270b into a single PDCCH will be described later.

[0106] In step S3110, UE100 performs precoding of PUSCH#1 and PUSCH#2 based on the SRI, RI, and TPMI integrated by the first TRP270a and the second TRP270b.

[0107] In step S3120, UE100 transmits a combined signal of PUSCH#1 and PUSCH#2 to DU260a via the first TRP270a. Here, as described above, PUSCH#1 and PUSCH#2 are precoded based on the SRI, RI, and TPMI integrated by the first TRP270a and second TRP270b. DU260a receives this signal.

[0108] In step S3130, UE100 transmits a combined signal of PUSCH#1 and PUSCH#2 to DU260a via the second TRP270b. Here, as described above, PUSCH#1 and PUSCH#2 are precoded based on the SRI, RI, and TPMI integrated by the first TRP270a and the second TRP270b. DU260a receives this signal.

[0109] In step S3140, DU260a performs postcoding of PUSCH#1 and PUSCH#2 using a single matrix formed by integrating PUSCH#1 and PUSCH#2. This postcoding separates PUSCH#1 and PUSCH#2. The single matrix formed by integrating PUSCH#1 and PUSCH#2 is the precoding matrix formed by integrating the first TRP270a and the second TRP270b. As mentioned above, channel information for postcoding is shared between the first TRP270a and the second TRP270b. As described above, the first TRP270a and the second TRP270b each receive a combined signal of PUSCH#1 and PUSCH#2, which are then separated by post-coding in DU260a. For simplicity, Figure 13 shows PUSCH#1 as the signal sent to the first TRP270a and PUSCH#2 as the signal sent to the second TRP270b.

[0110] Here, referring to Figures 14 to 16, the details of the method for determining the integrated SRI will be explained. As explained in step S380, DU260a performs MIMO channel estimation to correspond to both the channel between UE100 and the first TRP270a and the channel between UE100 and the second TRP270b. MIMO transmission using this MIMO channel estimation enables scheduling of PUSCH across the first TRP270a and the second TRP270b.

[0111] Figure 14 shows an example of a unique channel formed by SVD. For example, when MIMO transmission is performed using SVD, the gain of each layer is generally non-uniform. In the example shown in the figure, MIMO transmission is performed using four layers. Assume that the gain of each layer is greatest in the order of "Layer 1", "Layer 2", "Layer 3", and "Layer 4". For example, suppose that two pushers, PUSCH#1 and PUSCH#2, are used for transmission, with two layers each. In this case, depending on the priority, the following scheduling is possible.

[0112] Figure 15 shows an example of scheduling when transmitting with a higher priority for PUSCH#1 than for PUSCH#2. Layers with high gain, "Layer 1" and "Layer 2," are assigned to PUSCH#1. Layers with low gain, "Layer 3" and "Layer 4," are assigned to PUSCH#2.

[0113] Figure 16 shows an example of scheduling when transmitting with the priority of PUSCH#1 and PUSCH#2 being as similar as possible. Layers 1, 2, 3, and 4 are assigned alternately to the layers of PUSCH#1 and PUSCH#2 in order of increasing gain.

[0114] Here, referring to Figures 17 to 19, we will describe in detail how to multiplex the SRI, RI, and TPMI integrated by the first TRP270a and the second TRP270b into a single PDCCH. Figures 17 to 19 are diagrams showing an example of how to multiplex the SRI, RI, and TPMI integrated by the first TRP270a and the second TRP270b into a single PDCCH in the case of single panel transmission.

[0115] In one example shown in Figure 17, the integrated SRI, RI, and TPMI in the DCI transmitted over the PDCCH are multiplexed in an area half the size compared to the conventional multiplexing method for multi-panel transmission (see Figure 6).

[0116] In the example shown in Figure 18, the size of the area where the integrated SRI, RI, and TPMI are multiplexed is about the same as in the conventional multiplexing method for multi-panel transmission (see Figure 6). However, in the example shown in the same figure, the resolution of the codebook is increased to twice that of the codebook in the conventional multi-panel transmission. The resolution of the codebook is the number of bits in each component of the precoding matrix. Therefore, in the example shown in the same figure, a codebook with higher precision is defined compared to the Downlink Type I codebook.

[0117] In the example shown in Figure 19, the size of the area where the integrated SRI, RI, and TPMI are multiplexed is about the same as in the conventional multiplexing method for multi-panel transmission (see Figure 6). However, in the example shown in the same figure, the same data is multiplexed in an area half the size compared to the conventional multiplexing method for multi-panel transmission, thus providing data redundancy. This improves the reliability of the transmission of integrated SRI, RI, and TPMI.

[0118] Furthermore, one of the integrated SRI, RI, and TPMI multiplexing methods shown in Figures 17 to 19 for single-panel transmission may be used, selected according to the application. In that case, a parameter for specifying the multiplexing method will be provided.

[0119] In this embodiment, an example has been described in which, in a Codebook-type PUSCH transmission method in an ideal BH environment, multiple TRPs (first TRP270a and second TRP270b) are controlled by one DU (for example, DU260a) to perform coordination between the multiple TRPs. However, this is not limited to this example. Multiple TRPs may be controlled by each of the multiple DUs to perform coordination between the multiple TRPs. For example, the first TRP270a may be controlled by DU260a, and the second TRP270b may be controlled by DU260b, and coordination may be performed between the first TRP270a and the second TRP270b.

[0120] (2) Second Embodiment Referring to Figures 20 to 21, the second embodiment will be described, primarily focusing on the differences from the first embodiment. This embodiment describes codebook-type MIMO control in a non-ideal BH environment.

[0121] In a non-ideal BH environment, coordinated postcoding between multiple TRPs is not possible, so it is necessary to suppress inter-stream interference in precoding. In this embodiment, precoding is performed for push transmissions from the UE to two TRPs in the same manner as for multi-user MIMO (MU-MIMO). This embodiment describes the case in which a Downlink Type II codebook, used in codebook-type MU-MIMO transmission on the downlink, is used for transmission on the uplink of a Multi-TRP.

[0122] In this embodiment, UE100 is a user device that connects to each of a plurality of transmit / receive points (in this embodiment, the first TRP270a and the second TRP270b) in an environment where they do not perform coordinated control with each other. The receiver 110 receives an RRC message from at least one of the plurality of transmit / receive points that includes information indicating that there are multiple transmit / receive points. The transmitter 120 transmits a reference signal to each of the plurality of transmit / receive points on a single panel. The receiver 110 receives a first PDCCH from the first transmit / receive point, which is a reference signal in which information indicating a precoding index corresponding to a first precoding matrix calculated using the first reference signal transmitted to the first transmit / receive point and the codebook is multiplexed. The receiver 110 receives a second PDCCH from the second transmit / receive point, which is a reference signal in which information indicating a precoding index corresponding to a second precoding matrix calculated using the second reference signal transmitted to the second transmit / receive point and the codebook is multiplexed. The transmitting unit 120 transmits the first PUSCH and the second PUSCH to the first and second transmitting / receiving points, respectively, using a precoding matrix obtained by combining the first precoding matrix specified by the first PDCCH and the second precoding matrix specified by the second PDCCH.

[0123] As a result, even when multiple TRPs do not coordinate control with each other, the UE100 can suppress the decrease in SINR due to inter-panel interference associated with spatial multiplexing by using precoding weights calculated by considering the channel information between each of the multiple TRPs and the UE for multiple PUSCHs.

[0124] In this embodiment, node 200 is a node that connects to one of a plurality of transmit / receive points (in this embodiment, the first TRP270a and the second TRP270b) that are in an environment where they do not perform cooperative control with each other. The transmit unit 210 transmits an RRC message to UE100 that includes information indicating that there are multiple transmit / receive points. The receive unit 220 receives a reference signal from UE100, which has received the RRC message, via the first transmit / receive point among the plurality of transmit / receive points. The transmit unit 210 multiplexes information indicating a precoding index corresponding to a first precoding matrix calculated using the reference signal and the codebook, and transmits it to UE100 via the first transmit / receive point in the first PDCCH that is transmitted from the first transmit / receive point to UE100. The receiving unit 220 receives the PUSCH transmitted from the UE100 using a precoding matrix that combines the first precoding matrix specified by the first PDCCH and the second precoding matrix specified by the second PDCCH transmitted from the second transmission / reception point among the multiple transmission / reception points to the UE100.

[0125] As a result, even when multiple TRPs do not coordinate control with each other, node 200 can suppress the decrease in SINR due to inter-panel interference associated with spatial multiplexing by using precoding weights calculated by considering the channel information between each of the multiple TRPs and the UE for multiple PUSCHs.

[0126] (2.1) System operation example Referring to Figures 20 and 21, an example of system operation according to the second embodiment will be described, mainly focusing on the differences from the first embodiment. Figures 20 and 21 are diagrams showing an example of system operation according to the second embodiment. Note that the processing in step S450 is the same as the processing in step S330 in Figure 12, so the explanation is omitted. Also, the processing in steps S4120, S4130, S4150, and steps S4170 to S4190 is the same as the processing in steps S2130, S2140, S2160, and steps S2180 to S2200 in Figure 8, so the explanation is omitted. However, the difference is that the codebook used for precoding and postcoding is the Codebook 5 codebook described below.

[0127] In step S410, DU260a transmits PUSCH#1 configuration information (PUSCH-Config#1) to UE100 via the first TRP270a. UE100 receives the PUSCH#1 configuration information. The PUSCH#1 configuration information includes parameters for the SDM transmission mode and information indicating that there are multiple TRPs.

[0128] In step S420, DU260b transmits PUSCH#2 configuration information (PUSCH-Config#2) to UE100 via the second TRP270b. UE100 receives the PUSCH#2 configuration information. The PUSCH#2 configuration information includes parameters for the SDM transmission mode and information indicating that there are multiple TRPs.

[0129] In step S430, DU260a transmits the resource settings for SRS#1 to UE100 via the first TRP270a. UE100 receives the resource settings for SRS#1.

[0130] In step S440, DU260b sends the resource settings for SRS#2 to UE100 via the second TRP270b. UE100 receives the resource settings for SRS#2.

[0131] In step S460, the first TRP270a transmits SRS#1, which it received from UE100, to DU260a. DU260a receives SRS#1.

[0132] In step S470, the second TRP270b transmits SRS#2, which it received from UE100, to DU260b. DU260b receives SRS#2.

[0133] In step S480, DU260a calculates precoding matrix #1 corresponding to the channel between UE100 and the first TRP270a. Here, DU260a performs MIMO channel estimation for the channel between UE100 and the first TRP270a based on SRS#1 received at the first TRP270a, and calculates the precoding matrix (precoding weights). DU260a calculates the precoding weights based on SVD.

[0134] In step S490, DU260b calculates precoding matrix #2 corresponding to the channel between UE100 and the second TRP270b. Here, DU260b performs MIMO channel estimation for the channel between UE100 and the second TRP270b based on SRS#2 received by the second TRP270b, and calculates the precoding matrix (precoding weights). DU260b calculates the precoding weights based on SVD.

[0135] In this non-ideal BH environment, channel information is not shared between the first TRP270a and the second TRP270b. Therefore, channel estimation is performed independently for the channel between UE100 and the first TRP270a, and for the channel between UE100 and the second TRP270b.

[0136] In step S4100, DU260a determines the SRI, RI, and TPMI for the first TRP270a. Here, in determining the SRI, RI, and TPMI for the first TRP270a, DU260a applies the Codebook 5 codebook to Multi-TRP transmission as an example.

[0137] The Codebook5 codebook is a codebook for single-panel MIMO transmission that corresponds to the number of antenna ports on the UE100. The Codebook5 codebook supports multiple transmission paths (multipath) between the UE and multiple TRPs. The Codebook5 codebook is a high-precision codebook that applies the codebook used in downlink Codebook-type MU-MIMO transmission (Downlink Type II) to MIMO transmission of multiple TRPs using a single panel. The high precision of the Codebook5 codebook means that the resolution of each component of the precoding matrix is ​​higher than that of the codebook used when there is only one transmit / receive point.

[0138] Codebook 5 uses a precoder that assumes an antenna port configuration where N1 and N2 are the number of antenna elements in the horizontal and vertical directions of the antenna port, respectively, and (N1,N2) = (4,1) or (2,2). Note that Codebook 5 (Type II) controls not only the simple DFT (Discrete Fourier Transform) vector but also the amplitude. For more information on Codebook 5 (Type II), see, for example, Non-Patent Document 2.

[0139] The Codebook 5 codebook offers higher accuracy compared to the codebook used when there is only one transmit / receive point. Therefore, using the Codebook 5 codebook can suppress inter-panel interference compared to the codebook used when there is only one transmit / receive point.

[0140] Furthermore, the codebook used to determine the SRI, RI, and TPMI for the first TRP270a may be any codebook other than Codebook 5, as long as SVD transmission is possible.

[0141] In step S4110, DU260b determines the SRI, RI, and TPMI for the second TRP270b. The type of codebook used to determine the SRI, RI, and TPMI for the second TRP270b is the same as the codebook used in step S4100 (for example, Codebook 5).

[0142] In steps S4120 and S4130, the information indicating the precoding index for the first TRP270a and the information indicating the precoding index for the second TRP270b are multiplexed onto a single PDCCH in the same manner as the multiplexing shown in Figure 6.

[0143] In step S4140, UE100 performs precoding of PUSCH#1 based on the SRI, RI, and TPMI for the first TRP270a.

[0144] In step S4150, UE100 transmits the precoded PUSCH#1 to DU260a via the first TRP270a.

[0145] In step S4160, UE100 performs precoding of PUSCH#2 based on the SRI, RI, and TPMI for the second TRP270b.

[0146] In step S4170, UE100 transmits the precoded PUSCH#2 to DU260b via the second TRP270b.

[0147] Here, UE100 performs precoding of PUSCH#1 and PUSCH#2 using a precoding matrix obtained by combining the first precoding matrix specified by PDCCH#1 and the second precoding matrix specified by PDCCH#2. UE100 then uses all antenna ports to transmit PUSCH#1 to the first TRP270a and PUSCH#2 to the second TRP270b. UE100 then transmits a signal containing the multiplexed PUSCH#1 for the first TRP270a and PUSCH#2 for the second TRP270b on a single panel.

[0148] Therefore, UE100 transmits PUSCH#1 and PUSCH#2 using a precoding matrix obtained by combining the first precoding matrix specified in PDCCH#1 and the second precoding matrix specified in PDCCH#2.

[0149] The column size of the precoding matrix for a single panel is twice the size of the column size of the precoding matrix used in multi-panel transmission (precoding matrix #1 and precoding matrix #2 mentioned above).

[0150] Node 200 may switch its codebook depending on whether there is one transmit / receive point or multiple transmit / receive points.

[0151] (2) Modified form of the second embodiment Referring to Figures 22 to 26, a modified example of the second embodiment will be described, primarily focusing on the differences from the second embodiment.

[0152] In this modified example, when a node (DU260a, for example, in this embodiment) receives a reference signal from UE100 via one transmit / receive point, it requests channel information from another node (DU260b, for example, in this embodiment) connected to another transmit / receive point among the multiple transmit / receive points, regarding when that other transmit / receive point received the reference signal from UE100, and receives channel information from that other node.

[0153] This allows node 200 to calculate precoding weights by considering the channel information between each of the multiple TRPs and the UE, even when the multiple TRPs do not coordinate control with each other.

[0154] (2.2) System operation example Referring to Figures 22 and 23, a system operation example relating to a modified version of the second embodiment will be explained, mainly focusing on the differences from the second embodiment. Figures 22 and 23 are diagrams showing a system operation example relating to a modified version of the second embodiment. Note that the processes from step S510 to step S570 and from step S5160 to step S5230 are the same as the processes from step S410 to step S470 in Figure 20 and from step S4120 to step S4190 in Figure 21, so their explanation will be omitted.

[0155] In step S580, DU260a requests channel information from DU260b. This channel information is the channel information that the second TRP270b received from UE100 in step S570.

[0156] In step S590, DU260b sends channel information back to DU260a. DU260a receives channel information from DU260b.

[0157] In step S5100, DU260b requests channel information from DU260a. This channel information is the channel information obtained when the first TRP270a receives SRS#1 from UE100 in step S560.

[0158] In step S5110, DU260a sends channel information back to DU260b. DU260b receives channel information from DU260a. Details of the process for exchanging channel information will be described later.

[0159] In step S5120, DU260a calculates precoding matrix #1 corresponding to the channel between UE100 and the first TRP270a. Here, DU260a calculates the precoding matrix (precoding weight) based on SRS#1 received by the first TRP270a and channel information obtained from DU260b. As described above, this channel information is the channel information when the second TRP270b receives SRS#2 from UE100.

[0160] In step S5130, DU260b calculates precoding matrix #2 corresponding to the channel between UE100 and the second TRP270b. Here, DU260b calculates the precoding matrix (precoding weight) based on SRS#2 received by DU260b and channel information obtained from DU260a. As described above, this channel information is the channel information when the first TRP270a receives SRS#1 from UE100.

[0161] In the calculation of precoding matrix #1 using DU260a and precoding matrix #2 using DU260b, precoding weights are calculated using algorithms commonly found in MU-MIMO, such as Zero Forcing (ZF). Details of the precoding matrix calculation will be described later.

[0162] In step S5140, DU260a determines the SRI, RI, and TPMI for the first TRP270a. As an example, in determining the SRI, RI, and TPMI for the first TRP270a, the Codebook 6 codebook is applied to Multi-TRP transmission. Details of the Codebook 6 codebook will be described later.

[0163] In step S5150, DU260b determines the SRI, RI, and TPMI for the second TRP270b. The type of codebook used to determine the SRI, RI, and TPMI for the second TRP270b is the same as the codebook used in step S5410 (for example, Codebook 6).

[0164] Here, with reference to Figures 24 and 25, we will explain the details of the process for exchanging channel information. Figure 24 shows a conceptual diagram of channel information exchange. Note that the entities requesting channel information and those returning channel information are DU260a and DU260b, respectively. However, for simplicity, in this figure, they are referred to as 1st TRP270a and 2nd TRP270b, respectively. Figure 25 is a timing chart related to channel information exchange.

[0165] When DU260a receives SRS#1 from the first TRP270a, it requests channel information (channel matrix H2) from DU260b. When DU260b receives the request for channel information (channel matrix H2) from DU260a, it immediately transmits the channel information (channel matrix H2) and timing information to DU260a after receiving SRS#2 from the second TRP270b. The timing information indicates the time difference Δt2 between the time DU260b calculated the channel information (channel matrix H2) and the time DU260b transmitted the channel information to DU260a.

[0166] The first TRP270a corrects the channel information (channel matrix H2) to the channel information (channel matrix H2') at the current time, based on the time difference Δt2 indicated by the timing information and the inter-TRP communication delay time Δt1. The inter-TRP communication delay time Δt1 is the round-trip time from when DU260a requests channel information from DU260b until the channel information is sent back to DU260b from DU260b. Existing methods such as linear interpolation are used to correct the channel information. Nonlinear interpolation or other methods may also be used as correction methods. The timing information may also be information indicating the time when the DU260b calculated the channel information (channel matrix H2).

[0167] Similarly, when DU260b receives SRS#2 from the second TRP270b, it requests channel information from DU260a. When DU260a receives channel information from DU260b, it immediately sends the channel information back to DU260b after receiving SRS#1 from the first TRP270a. Therefore, the order of the processes from step S560 to step S5110 described above is not limited to that shown in the diagram. However, the order of steps S560, S580, and S590 is at least this order, and the order of steps S570, S5100, and S5110 is at least this order.

[0168] In this modified example, DU260a requests channel information from DU260b when the second TRP270b receives SRS#2 from UE100, and DU260b requests channel information from DU260a when the first TRP270a receives SRS#2 from UE100. In other words, this is an example of a DU requesting channel information from another DU when a TRP connected to that DU receives an SRS different from the SRS received by the TRP to which the DU itself is connected, but it is not limited to this. A DU may also request channel information from another DU when a TRP connected to that DU receives the same SRS as the TRP to which the DU itself is connected. For example, DU260a may request channel information from DU260b when the second TRP270b receives SRS#2 from UE100, and DU260b may request channel information from DU260a when the first TRP270a receives SRS#1 from UE100. Therefore, the DU may use either the same SRS it received or a different SRS to estimate channel information between a TRP different from the TRP it is connected to and the UE100.

[0169] In this modified example, an example has been described in which the request and return of channel information are performed directly between DU260a and DU260b, but this is not the only example. The request and return of channel information may also be performed between DU260a and DU260b via CU.

[0170] Next, we will explain the details of the calculation of the precoding matrix with reference to Figure 26. For simplicity, we will explain the case below where there are a total of 4 layers, with 2 layers for transmission by TRP#1 and 2 layers for transmission by TRP#2, and the channel matrix is ​​4 rows and 4 columns in size, but it is not limited to this case.

[0171] First, the precoding matrix W is calculated from a 4x4 channel matrix H=[H1H2'] which is obtained by combining the channel matrix H1 calculated based on SRS#1 and the corrected channel matrix H2'. Here, channel matrix H1 is a 2x4 channel matrix showing the estimated channels between UE100 and the first TRP270a. Channel matrix H2' is a 2x4 channel matrix showing the estimated channels between UE100 and the second TRP270b, which have been corrected for time as described above.

[0172] Next, the precoding matrix W is [W 1, It is decomposed into two 2x4 matrices, W1 and W2. The first TRP270a transmits matrix W1 in codebook format to UE100. Similarly, the second TRP270b transmits matrix W2 in codebook format to UE100.

[0173] UE100 transmits the SRS#1 signal, which is the transmission signal for the first TRP270a, to the first TRP270a by multiplying it by matrix W1 as a precoding weight. Similarly, UE100 transmits the SRS#2 signal, which is the transmission signal for the second TRP270b, to the second TRP270b by multiplying it by matrix W1 as a precoding weight.

[0174] This section describes the Codebook 6 codebook. In the Codebook 6 codebook, the components of the precoding matrix are specified by quantizing the amplitude and phase. In the Codebook 6 codebook, from the viewpoint of transmission efficiency, the components of the precoding matrix are specified using approximately 2 to 4 bits per parameter in the quantization of amplitude and phase. Here, one parameter is either amplitude or phase. Note that amplitude and phase correspond to the spatial granularity of the generated beam. In the MIMO transmission of multiple TRPs in this modified example, in order to properly form nulls, the Codebook 6 codebook, in which the amplitude and phase of the matrix components are quantized, is used instead of the Codebook type codebook used in the downlink Codebook type MU-MIMO transmission (Downlink Type II).

[0175] In Codebook 6, the number of antenna elements in the horizontal and vertical directions of the antenna port are assumed to be N1 and N2, respectively, such that (N1,N2) = (4,1) or (2,2).

[0176] Figure 26 shows a schematic diagram of the channels between UE100, multiplied by precoding weights, and multiple TRPs. In the channel between UE100 and the second TRP270b, the channel matrix H2' is multiplied by matrix W1 to form a null. On the other hand, in the channel between UE100 and the first TRP270a, as an example, ZF is applied to the calculation of the precoding weights, and an identity matrix is ​​formed.

[0177] (3) Third Embodiment Referring to Figures 27 to 32, the third embodiment will be described, primarily focusing on the differences from the second embodiment. This embodiment describes MIMO control using a hybrid configuration of Codebook type and Non-codebook type in a non-ideal BH environment.

[0178] The Block Diagonalization (BD) method is known as a technique for SDM transmission using MU-MIMO. In the BD method, each stream is determined by SVD, so a higher array gain can be obtained compared to ZF. However, the BD method has a high signal processing load because it performs precoding in two stages: multi-user isolation (suppression of inter-stream interference to multiple TRPs) and single-user isolation (spatial multiplexing within the same TRP). Therefore, in this embodiment, interference suppression by block diagonalization is performed by signal processing at the UE using non-codebook type precoding, and spatial multiplexing by SVD is performed by signal processing at the TRP (gNB) using codebook type precoding, thereby distributing the signal processing load to the UE and the nodes respectively.

[0179] In this embodiment, the UE100 receives an RRC message from node 200 containing first information indicating that the UE100 will use a first precoding matrix calculated by UE100 and a second precoding matrix specified by node 200 as the precoding matrix used for transmitting PUSCH. The transmitting unit 120 transmits a reference signal to node 200 using the first precoding matrix calculated by UE100. The transmitting unit 120 transmits PUSCH to node 200 using the first precoding matrix calculated by UE100 and the second precoding matrix specified by node 200.

[0180] This allows the UE100 to distribute the signal processing load between the UE100 and Node 200, thereby reducing the load on the UE100.

[0181] In this embodiment, node 200 transmits a first RRC message to UE100 that includes first information indicating that the precoding matrix used for transmitting PUSCH is a first precoding matrix calculated by UE100 and a second precoding matrix specified by node 200. The receiving unit 220 receives a plurality of reference signals transmitted from UE100 using the first precoding matrix calculated by UE100 after receiving the RRC message. The receiving unit 220 receives PUSCH transmitted from UE100 using the first precoding matrix calculated by UE100 and the second precoding matrix specified by node 200.

[0182] As a result, node 200 can distribute the signal processing load between UE100 and node 200, thereby reducing the load on node 200.

[0183] (3.1) System operation example Referring to Figures 27 and 28, an example of system operation according to the third embodiment will be explained, mainly focusing on the differences from the second embodiment. Figures 27 and 28 are diagrams showing an example of system operation according to the third embodiment. Note that the processing in steps S630, S640, S690, S6100, S6150, S6160, S6180, and steps S6200 to S6220 is the same as the processing in steps S430, S440, S460, S470 in Figure 20, and steps S4120, S4130, S4150, and steps S4170 to S4190 in Figure 21, so the explanation will be omitted.

[0184] In step S610, DU260a transmits PUSCH#1 configuration information (PUSCH-Config#1) to UE100 via the first TRP270a. UE100 receives the PUSCH#1 configuration information. The PUSCH#1 configuration information includes parameters for the SDM transmission mode, information indicating that there are multiple TRPs, and information indicating that a hybrid type precoding matrix will be used as the precoding matrix for transmitting PUSCH.

[0185] In step S620, DU260b transmits PUSCH#2 configuration information (PUSCH-Config#2) to UE100 via the second TRP270b. UE100 receives the PUSCH#2 configuration information. The PUSCH#2 configuration information includes parameters for the SDM transmission mode, information indicating that there are multiple TRPs, and information indicating that a hybrid precoding matrix will be used as the precoding matrix for transmitting PUSCH.

[0186] In step S650, DU260a transmits CSI-RS#1 to UE100. UE100 receives CSI-RS#1.

[0187] In step S660, DU260b sends CSI-RS#2 to UE100. UE100 receives CSI-RS#2.

[0188] In step S670, UE100 calculates Non-codebook type precoding weights based on CSI-RS#1 and CSI-RS#2.

[0189] Here, UE100 measures the resources of CSI-RS#1 transmitted in step S650. UE100 measures the resources of CSI-RS#2 transmitted in step S660. UE100 combines the channel matrix calculated from CSI-RS#1 with the channel matrix calculated from CSI-RS#2. UE100 then block-diagonalizes the resulting channel matrix to calculate the non-codebook type precoding weights. The BD method is used as an example for calculating the precoding weights. Details of the method for calculating non-codebook type precoding weights using the BD method will be described later.

[0190] In step S680, UE100 multiplies SRS#1 and SRS#2 by the calculated Non-codebook type precode value. UE100 then transmits SRS#1 to the first TRP270a and SRS#2 to the second TRP270b using all antenna ports. Note that in the transmission of SRS#1 and SRS#2 by UE100 using all antenna ports, the transmission of SRS#1 and SRS#2 may or may not occur simultaneously.

[0191] Here, if the RRC message contains both the second and first information, UE100 sends SRS#1 to DU260a using the first precoding matrix calculated by UE100. The first information, as described above, indicates that the first precoding matrix calculated by UE100 and the second precoding matrix specified by node 200 will be used as the precoding matrix for sending PUSCH. The second information, as described above, indicates that UE100 will perform uplink spatial multiplexing transmission on a single panel. If the RRC message contains both the second and the first information, UE100 sends SRS#2 to DU260b using the first precoding matrix calculated by UE100.

[0192] In step S6110, DU260a calculates precoding matrix #1 corresponding to the channel between UE100 and the first TRP270a. Here, DU260a performs MIMO channel estimation for the channel between UE100 and the first TRP270a based on SRS#1 received by the first TRP270a, and calculates the precoding matrix (precoding weights).

[0193] In step S6120, DU260b calculates precoding matrix #2 corresponding to the channel between UE100 and the second TRP270b. Here, DU260b performs MIMO channel estimation for the channel between UE100 and the second TRP270b based on SRS#2 received by the second TRP270b, and calculates the precoding matrix (precoding weights).

[0194] In this non-ideal BH environment, channel information is not shared between the first TRP270a and the second TRP270b. Therefore, channel estimation is performed independently for the channel between UE100 and the first TRP270a, and for the channel between UE100 and the second TRP270b. Furthermore, precoding weights are calculated based on the Codebook type calculation method. The calculation of precoding weights is based on SVD. Details of channel estimation and precoding weight calculation will be described later.

[0195] In step S6130, DU260a determines the SRI, RI, and TPMI for the first TRP270a. Here, in determining the SRI, RI, and TPMI for the first TRP270a, as an example, the Downlink Type I codebook (Codebook1) is applied to multi-TRP transmission.

[0196] Furthermore, the codebook used to determine the SRI, RI, and TPMI for the first TRP270a may be any codebook other than Codebook1, as long as SVD transmission is possible.

[0197] In step S6140, DU260b determines the SRI, RI, and TPMI for the second TRP270b. The type of codebook used to determine the SRI, RI, and TPMI for the second TRP270b is the same as the codebook used in step S6130 (for example, Codebook1).

[0198] In step S6190, UE100 performs Codebook-type precoding and Non-codebook-type precoding on PUSCH#1 based on the SRI, RI, and TPMI for the first TRP270a.

[0199] In step S6200, UE100 transmits the precoded PUSCH#1 to DU260a via the first TRP270a. DU260a receives the PUSCH#1.

[0200] Here, if the RRC message contains the second information described above and also contains the first information, UE100 sends a precoded PUSCH#1 to DU260a via the first TRP270a.

[0201] In step S6210, UE100 performs codebook-type precoding and non-codebook-type precoding on PUSCH#2 based on the SRI, RI, and TPMI for the second TRP270b.

[0202] In step S6220, UE100 transmits the precoded PUSCH#2 to DU260b via the second TRP270b. DU260b receives the PUSCH#2.

[0203] Here, if the RRC message contains the second information described above and also contains the first information, UE100 sends a precoded PUSCH#2 to DU260b via the second TRP270b.

[0204] Refer to FIGS. 29 and 30 here, and describe the transformation of the propagation channel by a hybrid precoding weight of the Codebook type and the Non-codebook type. First, calculate the Non-codebook type precoding weight. To calculate the precoding weight, as shown in FIG. 30, the channel matrix H1 calculated based on CSI-RS#1 and the channel matrix H2 calculated based on CSI-RS#2 are used. The channel matrix H is obtained by combining the channel matrix H1 and the channel matrix H2. By block diagonalizing the channel matrix H, the Non-codebook type precoding weight matrix W nc1 and the precoding weight matrix W nc2 are calculated respectively. The precoding weight matrix W nc1、 and the precoding weight matrix W nc2 are the precoding weight matrices for the propagation channels for the first TRP 270a and the second TRP 270b, respectively.

[0205] The channel matrix H1 is multiplied from the left by the precoding weight matrix W nc1 to obtain the block diagonalized channel matrix H1 ‘ The channel matrix H2 is multiplied from the left by the precoding weight matrix W nc2 to obtain the block diagonalized channel matrix H2 ‘ By block diagonalization, the inter-stream interference to multiple TRPs is suppressed.

[0206] Next, by diagonalizing the block diagonalized channel matrix H1 ‘ and the channel matrix H2 ‘ by SVD, the Codebook type precoding weight matrix W c1 and the precoding weight matrix W c2These are calculated accordingly. This enables spatial separation within the same TRP.

[0207] Block-diagonalized channel matrix H1 ‘ The precoding weight matrix W c1 It is multiplied from the right, and the postcoding matrix W is multiplied from the left. r1 The channel matrix D1 is obtained by multiplying by . The channel matrix D1 forms the intrinsic channel for the first TRP270a. Block diagonalized channel matrix H2 ‘ The precoding weight matrix W c2 It is multiplied from the right, and the postcoding matrix W is multiplied from the left. r2 The channel matrix D2 is obtained by multiplying by . The channel matrix D2 forms the intrinsic channel for the second TRP270b.

[0208] Postcoding matrix W for the first TRP270a r1 The channel matrix H 1、 Precoding weight matrix W nc1 , and the precoding weight matrix W c1 The postcoding matrix W for the second TRP270b is calculated based on the product of the following: r2 The channel matrix H 2、 Precoding weight matrix W nc2 , and the precoding weight matrix W c2 It is calculated based on the MMSE from the product of the two factors.

[0209] Figure 31 shows an overview of SRS signal transmission according to this embodiment, and a diagram illustrating the signal processing for SRS signal transmission. First, let's explain the signal processing in UE100. UE100 uses a non-codebook type precoding weight matrix W in SRS. nc Multiply by . As mentioned above, Non-codebook type precoding weight matrix W ncThis is calculated using the BD method. Here, the SRS transmitted from UE100 using a single panel is the SRS vector x s This is shown as: SRS vector x s This is a vector with dimensions equal to the number of antenna ports used by the UE100 for SRS transmission.

[0210] Furthermore, SRS#1 for the first TRP270a and SRS#2 for the second TRP270b are respectively defined as SRS vectors s s1 , and SRS vectors s2 This is shown as SRS vectors. s1 This is a vector with dimensions equal to the number of antenna ports used by UE100 for transmitting SRS#1 to the first TRP270a. SRS vector s s2 This is a vector with dimensions equal to the number of antenna ports used by UE100 for transmitting SRS#2 to the second TRP270b.

[0211] As shown in the figure, SRS vector x s This is the precoding weight matrix W nc1 SRS vectors multiplied by s s1 And the precoding weight matrix W nc2 SRS vectors multiplied by s s2 It is expressed as the sum of [the two terms].

[0212] Next, we will explain signal processing in the wireless section. In the wireless section, the SRS after propagation in the wireless section is called the SRS vector y s This is shown as the SRS vector y. sは、 SRS Vectorx s This is obtained by multiplying by the channel matrix H. Here, the SRS vector y s This is the SRS component vector y of SRS#1 for the first TRP270a. s1 And the SRS component vector y of SRS#2 for the second TRP270b s2 It is decomposed into the SRS component vector y s1This is a vector with dimensions equal to the number of antenna ports used for SRS#1 transmission among the antenna ports of the UE100. SRS component vector y s2 This is a vector with dimensions representing the number of antenna ports used for SRS#2 transmission among the antenna ports of the UE100.

[0213] SRS component vector y s1 , and SRS component vector y s2 When calculated, as shown in the figure, the off-diagonal components of the block obtained by block diagonalization are zero. This is because the Non-codebook type precoding weight matrix is ​​calculated such that the matrix multiplied by the SRS components in the off-diagonal components is zero (null). Specifically, the channel matrix H1 and the precoding weight matrix W nc2 The product of the channel matrix H2 and the precoding weight matrix W nc1 The product of each is zero (null).

[0214] Next, we will explain the signal processing in the TRP. Note that the signal processing in the first TRP270a and the signal processing in the second TRP270b are performed by DU260a and DU260b, respectively. In the first TRP270a, channel estimation is performed using the channel matrix H1 and the precoding weight matrix W nc1 The block-diagonalized channel matrix H1 is obtained by multiplying from the right. ‘ Let H1 be the channel matrix. ‘ By diagonalizing it using SVD, we obtain a Codebook-type precoding weight matrix W c1 This will be decided.

[0215] Similarly, in the second TRP270b, in channel estimation, the channel matrix H2 is used, and the precoding weight matrix W nc2 The block-diagonalized channel matrix H2 is obtained by multiplying from the right. ‘ Let H2 be the channel matrix.‘ By diagonalizing it using SVD, we obtain a Codebook-type precoding weight matrix W c2 This is determined. Note that the signal processing in the second TRP270b is signal processing by DU260b.

[0216] Figure 32 shows an overview of the transmission of the PUSCH signal according to this embodiment, and the signal processing for the transmission of the PUSCH signal. First, let's explain the signal processing in UE100. UE100 uses a Codebook-type precoding weight matrix W in PUSCH. c And the Non-codebook type precoding weight matrix W nc Multiply by . As mentioned above, the Codebook type precoding weight matrix W c is the channel matrix H1 ‘ (That is, the channel matrix H1 and the precoding weight matrix W) nc1 The product of (and) is calculated by diagonalizing it using SVD. Non-codebook type precoding weight matrix W nc This is calculated using the BD method. Here, the PUSCH signal transmitted from UE100 using a single panel is the PUSCH signal vector x p This is shown as follows: PUSCH signal vector x p This is a vector with dimensions equal to the number of antenna ports used by UE100 for PUSCH transmission.

[0217] Furthermore, PUSCH#1 for the first TRP270a and PUSCH#2 for the second TRP270b are respectively defined as PUSCH vector s p1 , and PUSCH vectors p2 This is shown as follows: PUSCH vector s p1 This is a vector with dimensions equal to the number of antenna ports used by UE100 for transmitting PUSCH#1 to the first TRP270a. PUSCH vector s p2is a vector of a dimension equal to the number of antenna ports of the antenna port used by the UE 100 for transmitting PUSCH #2 to the second TRP 270b.

[0218] As shown in the figure, the PUSCH signal vector x p is the precoding weight matrix W c1 and the PUSCH vector s nc1 multiplied by the precoding weight matrix W p1 and the precoding weight matrix W c2 and the PUSCH vector s nc2 multiplied by the precoding weight matrix W p2 and is expressed as the sum of the PUSCH vector s p1 First, the PUSCH vector s c1 is multiplied by the precoding weight matrix W nc1 and then multiplied by the precoding weight matrix W p2 and then multiplied by the precoding weight matrix W c2 and then multiplied by the precoding weight matrix W nc2 is multiplied. Similarly, for the PUSCH vector s

[0219] Next, signal processing in the radio interval will be described. In the radio interval, the PUSCH signal after propagating through the radio interval is shown as the PUSCH signal vector y p The PUSCH signal vector y pは、 The PUSCH signal vector y p is obtained by multiplying the PUSCH signal vector y p by the channel matrix H. Here, the PUSCH signal vector y p1 is decomposed into the PUSCH component vector y p2 of PUSCH #1 for the first TRP 270a and the PUSCH component vector y p1 of PUSCH #2 for the second TRP 270b. The PUSCH component vector y p2 p2is a vector in the dimension of the number of antenna ports used for the transmission of PUSCH #2 among the antenna ports of UE100.

[0220] PUSCH component vector y p1 and PUSCH component vector y p2 When calculating, as shown in the figure, the off - diagonal components of the blocks obtained by block diagonalization become zero. This is because, as explained in the signal processing for the transmission of the SRS signal, the non - codebook type precoding weight matrix is calculated so that the matrix multiplied by the SRS components in the off - diagonal components becomes zero (null). Specifically, the product of the channel matrix H1 and the precoding weight matrix W nc2 and the product of the channel matrix H2 and the precoding weight matrix W nc1 are each zero (null).

[0221] Next, the signal processing at the TRP will be described. At the first TRP 270a, the received PUSCH component vector y p1 is represented as a vector multiplied by the channel matrix D1, which is the product of the post - coding matrix W p1 and the precoding weight matrix W r1 and the channel matrix H1 ‘ 、 precoding weight matrix W c1 Here, the channel matrix D1 is diagonalized by SVD. Therefore, the components of the PUSCH component vector y p1 are represented as the values obtained by multiplying the components s p1 of the PUSCH vector s p11 and the component s p12 by the eigenvalues λ 11 and the eigenvalue λ 12 of the channel matrix D1. Thus, the PUSCH vector s p1 can be detected from the components of the received PUSCH component vector y 11 and the eigenvalues λ 12 and the eigenvalue λ p1 of the channel matrix D1.

[0222] In the second TRP270b, the received PUSCH component vector y p2 PUSCH vectors p2 The postcoding matrix W r2 , channel matrix H2 ‘ 、 Precoding weight matrix W c2 It is expressed as a vector multiplied by the channel matrix D2, which is the product of the two. Here, the channel matrix D2 is diagonalized by SVD. Therefore, the PUSCH component vector y p2 The components are the PUSCH vector s p2 The ingredients p21 , and component s p22 The eigenvalues ​​λ of the channel matrix D2 are located in the channel matrix D2. 21 , and eigenvalue λ 22 It is expressed as the value obtained by multiplying by . This gives the received PUSCH component vector y p2 The components and the eigenvalues ​​λ of the channel matrix D2 21 , and eigenvalue λ 22 From PUSCH vector s p2 It can be detected.

[0223] As described above, the channel matrix H1 and the precoding weight matrix W nc2 The product of the channel matrix H2 and the precoding weight matrix W nc1 The product of each is zero (null). Therefore, the precoding matrix calculated by UE100 is the PUSCH vector s to send to the first TRP270a. p1 And the PUSCH vector s to send to the second TRP270b p2 This is a precoding matrix in which PUSCH#1 transmitted by UE100 to the first TRP270a does not interfere with the second TRP270b, and PUSCH#2 transmitted by UE100 to the second TRP270b does not interfere with the first TRP270a.

[0224] In the embodiments described above, an example was given where there are two TRPs in SDM transmission of PUSCH using Multi-TRP, but this is not the only example. The SDM transmission of PUSCH in the embodiments described above can also be applied when there are three or more TRPs. However, if an upper limit is not set for the number of TRPs that can cooperate to control each other, an extension of the codebook specification (dimensional extension of the precoding matrix) will be necessary.

[0225] A program may be provided that causes a computer (UE100, node200) to perform the operations according to the above embodiment. The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM or DVD-ROM.

[0226] Although one embodiment of this invention has been described in detail above with reference to the drawings, the specific configuration is not limited to that described above, and various design changes can be made without departing from the spirit of this invention. [Explanation of symbols]

[0227] 1…Network 10...RAN 20…CN 100…UE 110... Receiver 120...Transmitter 130... Control Unit 140... Wireless Communication Department 200...nodes 210...Transmitter 220... Receiver 230... Control Unit 240...NW Communications Department 250... Wireless Communication Department 300…CN device

Claims

1. A node that connects to one of several transmit / receive points in an environment where they do not perform cooperative control with each other, An RRC message containing information indicating that there are multiple transmission and reception points is sent to the user device. The user device that received the RRC message receives the first reference signal via the first transmission / reception point among the plurality of transmission / reception points. The first physical downlink control channel transmitted from the first transmission / reception point to the user device is multiplexed with information indicating a precoding index corresponding to a first precoding matrix calculated using the first reference signal and the codebook, and transmitted to the user device via the first transmission / reception point. The user device receives a physical uplink shared channel transmitted using a precoding matrix that combines the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel transmitted from the second transmission / reception point among the plurality of transmission / reception points to the user device. The second precoding matrix is ​​a precoding matrix calculated using the second reference signal transmitted by the user device to the second transmit / receive point and the codebook. node.

2. The first reference signal and the second reference signal are transmitted by the user device on a single panel. The node according to claim 1.

3. The physical uplink sharing channel is transmitted by the user device on a single panel. The node according to claim 1 or claim 2.

4. The aforementioned codebook offers higher accuracy compared to the codebook used when there is only one transmit / receive point. The node according to claim 1.

5. The codebook is switched depending on whether there is one transmit / receive point or multiple transmit / receive points. The node according to claim 1.

6. When a reference signal is received from the user device via one of the transmission / reception points, the system requests channel information from other nodes connected to the other transmission / reception points among the plurality of transmission / reception points, which was received when the other transmission / reception point received the reference signal from the user device, and receives the channel information from the other nodes. The node according to claim 1.

7. The components of the precoding matrix are specified by quantizing the amplitude and phase. The node according to claim 4.

8. An RRC message containing information to cause the user device to perform uplink spatial multiplexing on a single panel is sent to the user device. The node according to claim 1.

9. The information indicating the precoding index includes RI, TPMI, and SRI. The node according to claim 1.

10. A user device that connects to multiple transmission and reception points in an environment where they do not perform coordinated control with each other, An RRC message containing information indicating that there are multiple transmission / reception points is received from at least one of the multiple transmission / reception points. A reference signal is transmitted to each of the aforementioned multiple transmission and reception points using a single panel. A first physical downlink control channel is received from the first transmission / reception point, in which information indicating a precoding index corresponding to a first precoding matrix calculated using the first reference signal transmitted to the first transmission / reception point among the plurality of transmission / reception points and the codebook is multiplexed. A second physical downlink control channel is received from the second transmission / reception point, in which information indicating a precoding index corresponding to a second precoding matrix calculated using the second reference signal transmitted to the second transmission / reception point among the plurality of transmission / reception points and the codebook is multiplexed. The first physical uplink sharing channel and the second physical uplink sharing channel are transmitted to the first and second transmission / reception points, respectively, using a precoding matrix obtained by combining the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel. User device.

11. The first physical uplink sharing channel and the second physical uplink sharing channel are transmitted to the first transmit / receive point and the second transmit / receive point respectively via a single panel. The user device according to claim 10.

12. A first node connected to a first transmit / receive point among multiple transmit / receive points in an environment where they do not perform cooperative control with each other, A second node connected to a second transmission / reception point among the plurality of transmission / reception points, A user device connected to each of the aforementioned plurality of transmitting and receiving points, Equipped with, The first node is, An RRC message containing information indicating that there are multiple transmission and reception points is sent to the user device. The user device that received the RRC message receives the first reference signal via the first transmit / receive point. The first physical downlink control channel transmitted from the first transmission / reception point to the user device is multiplexed with information indicating a precoding index corresponding to a first precoding matrix calculated using the first reference signal and the codebook, and transmitted to the user device via the first transmission / reception point. The aforementioned second node is, An RRC message containing information indicating that there are multiple transmission and reception points is sent to the user device. The user device that received the RRC message receives a second reference signal via the second transmission / reception point. The second physical downlink control channel transmitted from the second transmission / reception point to the user device is multiplexed with information indicating a precoding index corresponding to a second precoding matrix calculated using the second reference signal and the codebook, and transmitted to the user device via the second transmission / reception point. The User device is An RRC message containing information indicating that there are multiple transmission / reception points is received from at least one of the multiple transmission / reception points. A reference signal is transmitted to each of the aforementioned multiple transmission and reception points using a single panel. The first physical downlink control channel, on which information indicating the precoding index corresponding to the first precoding matrix is ​​multiplexed, is received from the first transmit / receive point. The second physical downlink control channel, on which information indicating the precoding index corresponding to the second precoding matrix is ​​multiplexed, is received from the second transmit / receive point. The first physical uplink sharing channel and the second physical uplink sharing channel are transmitted to the first and second transmission / reception points, respectively, using a precoding matrix obtained by combining the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel. The first node is, The first physical uplink sharing channel transmitted using a precoding matrix formed by combining the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel is received from the user device. The aforementioned second node is, The user device receives the second physical uplink sharing channel, which is transmitted using a precoding matrix obtained by combining the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel. Communication system.

13. The user device transmits the first physical uplink sharing channel and the second physical uplink sharing channel to the first transmit / receive point and the second transmit / receive point, respectively, on a single panel. The communication system according to claim 12.

14. A communication method used by a node connected to one of several transmitting / receiving points in an environment where they do not perform cooperative control with each other, The steps include sending an RRC message to the user device that includes information indicating that there are multiple transmission and reception points, The steps include receiving a first reference signal from the user device that received the RRC message via a first transmission / reception point among the plurality of transmission / reception points, The steps include multiplexing information indicating a precoding index corresponding to a first precoding matrix calculated using the first reference signal and the codebook onto a first physical downlink control channel transmitted from the first transmission / reception point to the user device, and transmitting this information to the user device via the first transmission / reception point; The steps include receiving a physical uplink shared channel from the user device using a precoding matrix that combines the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel transmitted from the second transmission / reception point among the plurality of transmission / reception points to the user device, It has, The second precoding matrix is ​​a precoding matrix calculated using the second reference signal transmitted by the user device to the second transmit / receive point and the codebook. Communication method.

15. The first reference signal and the second reference signal are transmitted by the user device on a single panel. The communication method according to claim 14.

16. The physical uplink sharing channel is transmitted by the user device on a single panel. The communication method according to claim 14.

17. A communication method used in user equipment that connects to multiple transmission and reception points in an environment where they do not perform coordinated control with each other, The steps include receiving an RRC message containing information indicating that there are multiple transmission / reception points from at least one of the multiple transmission / reception points, The steps include: transmitting a reference signal to each of the aforementioned multiple transmission and reception points using a single panel; The steps include receiving a first physical downlink control channel from the first transmission / reception point, in which information indicating a precoding index corresponding to a first precoding matrix calculated using the first reference signal transmitted to the first transmission / reception point among the plurality of transmission / reception points and the codebook is multiplexed, The steps include receiving a second physical downlink control channel from the second transmission / reception point, in which information indicating a precoding index corresponding to a second precoding matrix calculated using the second reference signal transmitted to the second transmission / reception point among the plurality of transmission / reception points and the codebook is multiplexed, The steps include transmitting a first physical uplink sharing channel and a second physical uplink sharing channel to the first and second transmission / reception points, respectively, using a precoding matrix obtained by combining the first precoding matrix specified in the first physical downlink control channel and the second precoding matrix specified in the second physical downlink control channel, A communication method that includes [something].

18. In the step of transmitting the first physical uplink sharing channel and the second physical uplink sharing channel to the first and second transmission / reception points, respectively, using the precoding matrix, the first physical uplink sharing channel and the second physical uplink sharing channel are transmitted to the first and second transmission / reception points, respectively, in a single panel. The communication method according to claim 17.

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