User equipment, node, and communication method

Abstract

This user equipment performs wireless communication with a node in a mobile communication system, and comprises a receiving unit that receives a first reference signal transmitted by a node, a control unit that measures a resource of the first reference signal, calculates, on the basis of the measurement of the resource of the first reference signal, a precoder to be used for transmitting a first physical uplink shared channel, and applies the precoder to the first physical uplink shared channel, and a transmitting unit that transmits, to the node, the first physical uplink shared channel to which the precoder has been applied, wherein the control unit maps first transmission target data to a plurality of layers of the first physical uplink shared channel such that the first transmission target data differ between the plurality of layers.

Description

User equipment, node, and communication method

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

[0002] NR (New Radio), a fifth-generation (5G) standard formulated by the Third Generation Partnership Project (3GPP (registered trademark; the same applies hereinafter)), a standardization project for mobile communication systems, specifies codebook and non-codebook transmission methods for transmitting the physical uplink shared channel (PUSCH). In the non-codebook type, a precoder determined by the node is applied to the transmission of the PUSCH.

[0003] In the non-codebook type transmission method, there is a problem that it takes a long time for the precoder to be applied to the PUSCH. In the non-codebook type transmission method, after a node (also simply referred to as "node") of a network of a mobile communication system transmits CSI-RS to a user equipment (UE), two round trips of communication are performed between the node and the UE until the PUSCH to which the precoder is applied is received.

[0004] As a result, particularly in an environment where the propagation channel fluctuates significantly, the propagation channel may fluctuate significantly between the time the precoder is calculated and the time the precoder is applied, resulting in a non-optimal precoder. Examples of environments where the propagation channel fluctuates significantly include an environment where a UE moves at high speed, or an environment where wireless communication using a high frequency band such as millimeter waves or sub-terahertz waves is used. In the latter wireless communication using a high frequency band, the beam is sharper than in a low frequency band, so even a slight change in the environment can cause greater channel fluctuations. If the precoder becomes non-optimal, inter-stream interference in the received signal increases, degrading modulation accuracy and potentially reducing throughput.

[0005] 3GPP Technical Specification: TS 38.214 V18.0.0 (2023-09)

[0006] A user equipment according to a first aspect is a user equipment that performs wireless communication with a node in a mobile communication system, and includes: a receiving unit that receives a first reference signal transmitted by the node; a control unit that measures resources of the first reference signal, calculates a precoder to be used for transmitting a first physical uplink shared channel based on the measurement of the resources of the first reference signal, and applies the precoder to the first physical uplink shared channel; and a transmitting unit that transmits the first physical uplink shared channel to which the precoder has been applied to the node, wherein the control unit maps the first data to be transmitted to the multiple layers such that the first data to be transmitted differs among the multiple layers of the first physical uplink shared channel.

[0007] A node according to a second aspect is a node that performs wireless communication with a user equipment in a mobile communication system, and includes: a transmitter that transmits a first reference signal to the user equipment; and a receiver that receives from the user equipment a first physical uplink shared channel that the user equipment transmitted by applying a precoder calculated based on measurement of a resource of the first reference signal, wherein the first data to be transmitted is mapped to a plurality of layers of the first physical uplink shared channel such that the first data to be transmitted differs among the plurality of layers of the first physical uplink shared channel.

[0008] A communication method according to a third aspect is a communication method used by a user equipment that performs wireless communication with a node in a mobile communication system, the method comprising the steps of: receiving a first reference signal transmitted by the node; measuring a resource of the first reference signal; calculating a precoder to be used for transmitting a first physical uplink shared channel based on the measurement of the resource of the first reference signal; applying the precoder to the first physical uplink shared channel; and transmitting the first physical uplink shared channel to which the precoder has been applied to the node, wherein the first data to be transmitted is mapped to the multiple layers such that the first data to be transmitted differs among the multiple layers of the first physical uplink shared channel.

[0009] A communication method according to a fourth aspect is a communication method used in a node that performs wireless communication with a user equipment in a mobile communication system, the method comprising: a step of transmitting a first reference signal to the user equipment; and a step of receiving from the user equipment a first physical uplink shared channel that the user equipment transmitted by applying a precoder calculated based on measurement of a resource of the first reference signal, wherein first data to be transmitted is mapped to a plurality of layers of the first physical uplink shared channel such that the first data to be transmitted differs among the plurality of layers of the first physical uplink shared channel.

[0010] 1 is a diagram showing an example of the configuration of a mobile communication system according to an embodiment. FIG. 2 is a diagram showing an example of the configuration of a protocol stack of a radio interface of a U-plane that handles data. FIG. 3 is a diagram showing an example of the configuration of a protocol stack of a radio interface of a C-plane that handles signaling (control signals). FIG. 4 is a diagram showing a general procedure in which a precoder determined in a non-codebook type is applied to transmit a physical uplink shared channel. FIG. 5 is a diagram showing an example of the configuration of a UE (user equipment) according to an embodiment. FIG. 6 is a diagram showing an example of the configuration of a node according to an embodiment. FIG. 7 is a diagram showing an example of a system operation according to the first embodiment. FIG. 8 is a diagram showing an example of a system operation according to a modified example of the second embodiment. FIG. 9 is a diagram showing an example of a system operation according to a modified example of the second embodiment. FIG. 10 is a diagram showing an example of a system operation according to a modified example of the third embodiment. FIG. 11 is a diagram showing an example of a system operation according to a first modified example of the third embodiment. FIG. 12 is a diagram showing an example of a system operation according to a second modified example of the third embodiment. FIG. 13 is a diagram showing an example of a system operation according to a third modified example of the third embodiment.

[0011] Hereinafter, a mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0012] (1) First Embodiment A first embodiment will be described with reference to FIGS. 1 to 7. FIG.

[0013] (1.1) System Configuration Example Fig. 1 is a diagram showing a configuration example of a mobile communication system according to an embodiment. The mobile communication system according to the embodiment is a system conforming to 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.

[0014] The mobile communication system includes a network (NW) 1 and a user equipment (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), a tablet terminal, a notebook PC (Personal Computer), a communication module (including a communication card or chipset), a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), or an aircraft or a device provided in an aircraft (Aerial UE). The UE 100 may be a Mobile Termination (MT) of a relay device such as an Integrated Access and Backhaul (IAB) or a Network-Controlled Repeater (NCR).

[0015] NW1 includes a radio access network (RAN) 10 and a core network (CN) 20. When the mobile communication system is a 5th generation system (5GS), the RAN 10 is referred to as a Next Generation Radio Access Network (NG-RAN), and the CN 20 is referred to as a 5G Core Network (5GC).

[0016] The RAN 10 includes a plurality of nodes 200 (nodes 200a to 200c in the illustrated example). The nodes 200 are connected to each other via inter-node interfaces. The nodes 200 are also referred to as base stations. The nodes 200 may be configured (i.e., functionally divided) with a CU (Central Unit) and a DU (Distributed Unit), and the two units may be connected by a fronthaul interface. When the mobile communication system is 5GS, the nodes 200 are referred to as gNBs, the inter-node interface is referred to as an Xn interface, and the fronthaul interface is referred to as an F1 interface.

[0017] Each node 200 manages one or more cells. The node 200 performs wireless communication with the UE 100 that has established a connection with its own cell. Each node 200 has a radio resource management (RRM) function, a routing function for user data (also simply referred to as "data"), a measurement control function for mobility control and scheduling, and the like. Note that "cell" is used as a term indicating the smallest unit of a wireless communication area. "Cell" is also used as a term indicating a function or resource for performing wireless communication with the UE 100. One cell belongs to one carrier frequency (also simply referred to as "frequency").

[0018] The CN 20 includes a CN device 300. The 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 the UE 100. The C-plane device communicates with the UE 100 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 referred to as an AMF (Access and Mobility Management Function), the U-plane device is referred to as a UPF (User Plane Function), and the interface between the node 200 and the CN device 300 is referred to as an NG interface.

[0019] FIG. 2 is a diagram showing an example of the configuration of a protocol stack of a U-plane radio interface that handles data.

[0020] The U-plane radio interface protocol includes, for example, a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0021] 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 UE 100 and the PHY layer of node 200 via a physical channel. The PHY layer of UE 100 receives downlink control information (DCI) transmitted from node 200 on a physical downlink control channel (PDCCH). Specifically, UE 100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and acquires successfully decoded DCI as DCI addressed to the UE. The DCI transmitted from node 200 has CRC parity bits scrambled by the RNTI added.

[0022] 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 UE 100 and the MAC layer of node 200 via a transport channel. The MAC layer of node 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resources to be allocated to UE 100.

[0023] The RLC layer transmits data to the RLC layer on the receiving side by using the functions of the MAC layer and the PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the node 200 via logical channels.

[0024] The PDCP layer performs header compression / decompression, encryption / decryption, and the like.

[0025] The SDAP layer maps IP flows, which are units for QoS control by the CN 20, to radio bearers, which are units for QoS control by the AS (Access Stratum). Note that if the RAN is connected to the EPC, SDAP may not be required.

[0026] FIG. 3 is a diagram showing an example of the configuration of a protocol stack of a C-plane radio interface that handles signaling (control signals).

[0027] The protocol stack of the C-plane radio interface includes, for example, an RRC (Radio Resource Control) layer and an NAS (Non-Access Stratum) layer instead of the SDAP layer shown in FIG.

[0028] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of node 200. The RRC layer controls logical channels, transport channels, and physical channels in accordance with the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of node 200, UE100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of node 200, UE100 is in an RRC idle state. When the connection between the RRC of UE100 and the RRC of node 200 is suspended, UE100 is in an RRC inactive state.

[0029] The NAS layer (also simply referred to as "NAS") located above the RRC layer performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the CN device 300. Note that the UE 100 also has an application layer in addition to the radio interface protocol. The layer below the NAS layer is referred to as the AS layer (also simply referred to as "AS").

[0030] FIG. 4 is a diagram illustrating a general procedure for transmitting a Physical Uplink Shared Channel (PUSCH) in a non-codebook manner.

[0031] In step S10, the node 200 transmits a resource configuration of an SRS (Sounding Reference Signal) to the UE 100. The UE 100 receives the resource configuration of the SRS. By this resource configuration, resources (frequency, time, antenna port) of the SRS are configured.

[0032] In step S20, the node 200 transmits the CSI-RS to the UE 100. The UE 100 receives the CSI-RS.

[0033] In step S30, the UE 100 measures the resource of the CSI-RS transmitted in step S20. The UE 100 calculates a precoder to be used for transmitting the SRS based on the measurement of the resource of the CSI-RS.

[0034] In step S40, the UE 100 applies the calculated precoder and transmits up to four SRSs to the node 200. For transmitting these SRSs, the SRS resources set by the resource configuration received in step S10 are used. Furthermore, one SRS antenna port is set for the SRS resource of each SRS.

[0035] In step S50, the node 200 determines one or more SRS Resource Indicators (SRIs) corresponding to the precoders used for transmitting the PUSCH, based on the received SRS.

[0036] In step S60, the node 200 transmits the determined one or more SRIs to the UE 100. Here, the one or more SRIs are transmitted by being included in downlink control information (DCI) transmitted on a physical downlink control channel (PDCCH). Here, the one or more SRIs are stored in an SRS resource indicator field within the field included in the DCI. The UE 100 receives the one or more SRIs. Also, in the non-codebook type transmission method, a TRI (Transmit Rank Indicator) is not notified from the node 200, but the UE 100 determines the TRI from the number of SRIs.

[0037] In step S70, the UE 100 transmits the PUSCH to the node 200 using the same antenna port as the antenna port of the SRS. The antenna port of the SRS is indicated by one or more received SRIs. As a result, the same precoder as that of the SRS of the SRS resource indicated by the received SRI is applied to the transmission of the PUSCH.

[0038] According to this procedure, two round trips of communication are made between the node 200 and the UE 100 from the time the node 200 transmits the CSI-RS to the UE 100 until the node 200 receives the PUSCH to which the precoder is applied. This poses a problem that the precoder may not be optimal, especially in an environment where the propagation channel fluctuates significantly. As a result, the throughput may decrease due to increased inter-stream interference and deterioration in modulation accuracy.

[0039] (1.2) Example of Configuration of User Equipment FIG. 5 is a diagram illustrating an example of the configuration of the UE 100 (user equipment) according to the embodiment.

[0040] The UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 configure a wireless communication unit 140 that performs wireless communication with the node 200.

[0041] The receiving unit 110 performs various receptions under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts a 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 transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmitted signal) output by the control unit 130 into a radio signal and transmits it from the antenna.

[0042] The control unit 130 performs various controls and processes in the UE 100. The operations of the UE 100 described above and below may be operations 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 in the processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0043] The UE 100 configured in this manner performs wireless communication with the node 200 in a mobile communication system. The receiver 110 receives a first reference signal transmitted by the node 200. The controller 130 measures resources of the first reference signal, calculates a precoder to be used for transmitting the PUSCH based on the measurement of the resources of the first reference signal, and applies the precoder to the PUSCH. The transmitter 120 transmits the PUSCH to which the precoder has been applied to the node 200. The controller 130 maps data to be transmitted to multiple layers of the PUSCH such that the data to be transmitted differs among the multiple layers.

[0044] The control unit 130 maps second data to be transmitted, which is different from the first data to be transmitted, to a second PUSCH that is transmitted after the first PUSCH to which the transmitting unit 120 has applied the precoder.

[0045] In this embodiment, the first reference signal is a downlink reference signal used to calculate a precoder to be applied to the transmission of the PUSCH. The first reference signal is, for example, a CSI-RS in 3GPP, but may be other reference signals such as a DM-RS or a new reference signal introduced in the sixth generation. Below, an example will be described in which the first reference signal is a CSI-RS.

[0046] As a result, the UE 100 can transmit the PUSCH with fewer round trips of communication than in the procedure of Fig. 4. By reducing the number of round trips of communication, the UE 100 can suppress a decrease in throughput due to an increase in inter-stream interference and a deterioration in modulation accuracy, even in an environment in which the propagation channel fluctuates significantly.

[0047] Furthermore, in this embodiment, the control unit 130 determines the number of layers of the PUSCH based on measurement of the resources of the first reference signal. Furthermore, in this embodiment, the control unit 130 calculates a precoder to be used for transmitting the second reference signal based on measurement of the resources of the first reference signal, selects antenna ports corresponding to the determined number of layers of the PUSCH from the antenna ports of the second reference signal, and uses the selected antenna ports for the number of layers for transmitting the PUSCH. As a result, the part of the precoder applied to transmission of the second reference signal that is used for the second reference signal of the selected antenna port is used for transmitting the PUSCH.

[0048] In this embodiment, the second reference signal is an uplink reference signal used by the node 200 to receive the PUSCH. The second reference signal is, for example, a sounding reference signal (SRS) in 3GPP, but may be other reference signals such as a DM-RS or a new reference signal introduced in the sixth generation. An example of the case where the second reference signal is an SRS will be described below.

[0049] (1.3) Example of Node Configuration FIG. 6 is a diagram illustrating an example of the configuration of a node 200 (base station, gNB) according to an embodiment.

[0050] The node 200 includes a transmitting unit 210, a receiving unit 220, a control unit 230, and a NW communication unit 240. The transmitting unit 210 and the receiving unit 220 configure a wireless communication unit 250 that performs wireless communication with the UE 100.

[0051] The transmitting unit 210 performs various transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts a 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 receptions under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (reception signal) and outputs it to the control unit 230.

[0052] The control unit 230 performs various controls and processes in the node 200. The operations of the node 200 described above and below may be operations under the control of 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 in the processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0053] The NW communication unit 240 is connected to adjacent nodes via an inter-node interface, and to the CN device 300 via a node-CN interface.

[0054] The node 200 configured in this manner performs wireless communication with the UE 100 in a mobile communication system. The transmitter 210 transmits a first reference signal to the UE 100. The receiver 220 receives a PUSCH from the UE 100. The PUSCH is a PUSCH transmitted by the UE 100 by applying a precoder calculated based on measurement of the resource of the first reference signal.

[0055] (1.4) System Operation Example Figure 7 is a diagram showing an example of system operation according to the first embodiment. The system operation according to the first embodiment is a method of transmitting a PUSCH to which a UE-determined precoder is applied, that is, a method of transmitting a PUSCH to which a precoder determined by UE 100 is applied. Note that duplicated explanations of operations similar to those in Figure 4 will be omitted.

[0056] In step S110, the node 200 transmits a PUSCH resource configuration and an SRS resource configuration to the UE 100. The node 200 transmits the resource configuration to the UE 100, for example, in an RRC layer. Note that the node 200 may transmit the resource configuration to the UE 100 in a MAC layer, or may transmit the resource configuration to the UE 100 by including it in DCI. The UE 100 receives the PUSCH resource configuration and the SRS resource configuration.

[0057] In step S120, the node 200 transmits the CSI-RS to the UE 100. The UE 100 receives the CSI-RS. Note that the node 200 may transmit the CSI-RS to the UE 100 before transmitting the above-described PUSCH resource configuration and SRS resource configuration. That is, the order in which the process of step S120 and the process of step S110 are performed may be reversed from the order shown in FIG. 7 .

[0058] In step S130, the UE 100 measures the resource of the CSI-RS transmitted in step S120. The UE 100 calculates a precoder to be applied to the transmission of the PUSCH and the SRS based on the measurement of the resource of the CSI-RS. The UE 100 determines the number of layers of the PUSCH based on the measurement of the resource of the CSI-RS.

[0059] The method by which the UE 100 calculates the precoder to be applied to the transmission of the PUSCH and SRS based on the measurement of the CSI-RS resource is, for example, a method based on singular value decomposition. The UE 100 expresses the result of the measurement of the CSI-RS resource as a matrix having rows corresponding to the number of antenna ports of the node 200 and columns corresponding to the number of antenna ports of the UE 100 (the maximum number of layers of the PUSCH). The UE 100 performs singular value decomposition on the matrix. The UE 100 determines whether the magnitude of the singular value obtained by the singular value decomposition is greater than a predetermined threshold. The UE 100 determines that the beam is transmittable when the magnitude of the singular value is greater than the predetermined threshold. The eigenvector corresponding to the singular value determined to be transmittable corresponds to the precoder weight of the beam (layer) determined to be transmittable, and the number of the eigenvectors corresponds to the number of transmittable layers. The method by which UE 100 calculates the precoder to be applied to the transmission of the PUSCH based on the measurement of the CSI-RS resource is not limited to the method based on singular value decomposition, and other methods may be used.

[0060] In step S140, UE 100 transmits SRS of up to four layers to which the calculated precoder has been applied, and PUSCH to which the calculated precoder has been applied, to node 200. Here, UE 100 transmits PUSCH to node 200 using the same antenna port as the antenna port of the SRS. Node 200 receives SRS and PUSCH. Note that the timing at which UE 100 transmits PUSCH to node 200 is scheduled by, for example, DCI. Furthermore, UE 100 transmits PUSCH to node 200 using resources set in the PUSCH resource configuration received from node 200 in step S110.

[0061] Note that UE 100 transmits SRS to node 200 using SRS resources of at least the above-mentioned number of layers. The above-mentioned number of layers is the number of layers determined by UE 100 based on the measurement of the CSI-RS resource in step S130 (that is, the number of PUSCH layers determined by UE 100). Note that UE 100 selects an antenna port for the determined number of PUSCH layers from the SRS antenna port, and uses the selected antenna port for transmitting PUSCH. As a result, the same precoder as the precoder used for transmitting SRS from the selected antenna port is applied, and PUSCH for the determined number of PUSCH layers is transmitted to node 200.

[0062] Here, the UE 100 maps the first data to be transmitted to the plurality of layers of the PUSCH such that the mapped data to be transmitted differs among the plurality of layers. In the example shown in Fig. 7, the UE 100 maps the first data to be transmitted to the three layers of PUSCH1, PUSCH2, and PUSCH3 such that the first data to be transmitted differs among the three layers.

[0063] In the example shown in FIG. 7 , an example has been described in which UE 100 transmits three SRSs (SRS1, SRS2, and SRS3) and three PUSCHs (PUSCH1, PUSCH2, and PUSCH3) using three layers out of a maximum of four layers in step S140. However, the operation of UE 100 of the present invention is not limited to this. UE 100 may use some of the antenna ports for SRS only for transmitting SRSs, and may not use these antenna ports for transmitting PUSCHs. For example, UE 100 may use the antenna port for SRS2 only for transmitting SRS2, and may not use it for transmitting PUSCH2. Also, UE 100 may transmit four SRSs using all of a maximum of four layers. Furthermore, the maximum number of layers may be other than four.

[0064] In step S150, the node 200 determines one or more SRIs corresponding to the precoders to be used for transmitting the PUSCH, based on the received SRS. In the example shown in Fig. 7, SRI1 and SRI3 are determined.

[0065] In step S160, the node 200 transmits the determined one or more SRIs to the UE 100. Here, the one or more SRIs are transmitted by being included in the DCI transmitted on the PDCCH. Here, the one or more SRIs are stored in an SRS resource indicator area among the areas included in the DCI. The UE 100 receives one or more SRIs. Also, in the PUSCH transmission method to which the UE-determined precoder is applied, as in the non-codebook type transmission method, the TRI is not notified from the node 200, but the UE 100 determines the TRI from the number of SRIs.

[0066] In step S170, UE 100 transmits a PUSCH to node 200 using the same antenna port as the antenna port of the SRS. The antenna port of the SRS is indicated by one or more received SRIs. As a result, the same precoder as that of the SRS of the SRS resource indicated by the received SRI is applied to the transmission of the PUSCH. Note that UE 100 may transmit an SRS to node 200 in step S170 before transmitting a PUSCH to node 200. In this case, UE 100 transmits an SRS to node 200 using SRS resources of at least the above-mentioned number of layers.

[0067] Here, UE 100 maps second transmission target data, which is different from the first transmission target data, mapped to PUSCH in step S140, to PUSCH in step S170. That is, UE 100 maps second transmission target data, which is different from the first transmission target data, to PUSCH to be transmitted next to PUSCH to which the precoder determined by UE 100 is applied. With this configuration, in this embodiment, the communication speed can be improved by up to twice as much as the conventional procedure shown in FIG.

[0068] The timing at which UE 100 transmits the PUSCH to node 200 in step S170 is scheduled by DCI, similar to the schedule of the timing at which UE 100 transmits the PUSCH to node 200 in step S140. The timing at which UE 100 transmits the PUSCH to node 200 in step S170 may be scheduled by DCI that node 200 transmits to UE 100 in step S160.

[0069] Note that the transmission of the SRS and the PUSCH from UE 100 to node 200 in step S140 may be performed multiple times before the processing from step S150 to step S170 is performed next time. Furthermore, the number of times the SRS and the PUSCH are transmitted may not be the same. Furthermore, the processing from step S140 to step S170 may be performed multiple times before the processing from step S110 to step S130 is performed next time.

[0070] As described above, the method of transmitting a PUSCH to which a UE-determined precoder according to this embodiment is applied includes an operation in which the UE 100 transmits a PUSCH to which a UE-determined precoder is applied (referred to as the operation of step S140), and an operation in which the UE 100 transmits a PUSCH to which the same precoder as that of the SRS of the SRS resource indicated by the SRI received from the node 200 is applied (referred to as the operation of step S170). The UE 100 switches between the operation of step S140 and the operation of step S170 depending on whether or not an SRI has been received from the node 200. In this case, if the UE 100 has not received an SRI from the node 200, the UE 100 performs the operation of step S140. On the other hand, if the UE 100 has received an SRI from the node 200, the UE 100 performs the operation of step S170. As another example, the CSI-RS received by the UE 100 in step S120 may include information for switching between the operation of step S140 and the operation of step S170. As another example, when transmitting a PUSCH next time after performing the operation of step S140, a predetermined operation procedure indicating that the operation of step S170 is to be performed may be stored in advance in the UE 100.

[0071] In other words, the operation of step S140 is an operation in which UE 100 determines a precoder for transmitting the PUSCH. On the other hand, the operation of step S170 is an operation in which node 200 determines a precoder for transmitting the PUSCH.

[0072] Here, in this embodiment, TDD (Time Division Duplex) is assumed in the PUSCH transmission method applying the UE-determined precoder shown in FIG. 7, that is, the PUSCH transmission method applying the precoder determined by the UE 100. The UE 100 can measure the CSI-RS received from the node 200 (that is, can perform channel estimation). The UE 100 uses channel reciprocity due to TDD to calculate the precoder to be used for transmitting the PUSCH based on the measurement of the CSI-RS, and also determines the number of layers of the PUSCH. In other words, the UE 100 has the ability to determine the precoder (beam) to be used for transmitting the PUSCH. The advantage of the PUSCH transmission method applying the UE-determined precoder is that the precoder to be used for transmission can be calculated from the received signal by using channel reciprocity due to TDD. That is, by executing a series of controls for transmitting the PUSCH in the UE 100 without communicating with the node 200, it is possible to determine the precoder in a shorter time than in the conventional procedure shown in FIG.

[0073] In the present embodiment, an example has been described in which the UE 100 (control unit 130) determines the number of layers of the PUSCH based on measurement of resources of the first reference signal (CSI-RS), but this is not limiting. The number of layers of the PUSCH does not have to be determined by the UE 100. In that case, for example, the node 200 determines the number of layers of the PUSCH, and the node 200 notifies the UE 100 of the determined number of layers. As another example, the number of layers of the PUSCH may be determined in advance, and the UE 100 may store the number of layers in advance.

[0074] In addition, in this embodiment, the UE 100 (control unit 130) calculates a precoder used for transmitting a second reference signal (SRS) based on measurement of the resource of the first reference signal (CSI-RS), selects an antenna port for the determined number of layers of the PUSCH from the antenna ports of the second reference signal (SRS), and transmits the PUSCH using the selected antenna port. However, this is not limited to this. The UE 100 may transmit the PUSCH using an antenna port other than the antenna port of the second reference signal (SRS).

[0075] (2) Second Embodiment With reference to FIG. 8 , the second embodiment will be described, focusing mainly on differences from the first embodiment. In the first embodiment described above, the UE 100 can transmit the PUSCH with fewer round-trip communication operations than in the procedure of FIG. 4 . Therefore, even in an environment where the propagation channel fluctuates significantly, the number of round-trip communication operations can be reduced to prevent a decrease in throughput due to increased inter-stream interference and degraded modulation accuracy. However, if a sudden deterioration in reception quality occurs due to a line failure or the like, loss of data to be transmitted may occur. For example, in an environment where wireless communication using a high frequency band such as sub-terahertz waves is used, a sudden deterioration in reception quality, such as when an obstruction crosses the transmission path, may cause a deterioration in reception quality. In the second embodiment, the control unit 130 maps data to be transmitted to all layers of the PUSCH so that the data to be transmitted is the same across all layers of the PUSCH.

[0076] (2.1) System Operation Example A system operation example according to the second embodiment will be described, focusing on differences from the first embodiment, with reference to Fig. 8. Fig. 8 is a diagram showing a system operation example according to the second embodiment. Note that the processes of steps S210, S220, S230, S250, S260, and S270 are similar to the processes of steps S110, S120, S130, S150, S160, and S170 in Fig. 7, and therefore will not be described again.

[0077] In step S240, UE 100 transmits PUSCH and SRS to node 200. Here, UE 100 maps the data to be transmitted to the layer of PUSCH so that the data to be transmitted is the same among all layers of PUSCH. In other words, UE 100 multiplexes the same data to be transmitted onto all layers of PUSCH. With this configuration, in this embodiment, it is possible to improve the reliability of the data to be transmitted.

[0078] 7 in that UE 100 maps second data to be transmitted, which is different from the first data to be transmitted that was mapped to PUSCH in step S240, to PUSCH in step S270.

[0079] As described above, in the second embodiment, the same data to be transmitted is multiplexed in all layers of the PUSCH in step S240. When the node 200 receives the data to be transmitted as received data, the node 200 restores the original data to be transmitted from the multiplexed received data. Any method may be used for the restoration. For example, the node 200 selects the received data with the highest quality from the multiplexed received data in the MAC layer. As another example, the node 200 may soft-combine the multiplexed received data in the physical (PHY) layer. When soft-combining is used for the restoration, the UE 100 may transmit the multiplexed data to be transmitted by varying the HARQ redundancy version (i.e., redundant configuration) between layers.

[0080] (2.2) Modification of Second Embodiment With reference to FIG. 9 , a modification of the second embodiment will be described, focusing mainly on differences from the second embodiment. In the above-described first embodiment, a case has been described in which the UE 100 multiplexes the same transmission target data onto all layers of the PUSCH. While multiplexing the same transmission target data improves the reliability of the transmission target data, it also reduces transmission efficiency. In a modification of the second embodiment, the receiver 110 receives group information from the node 200. The group information is information for dividing at least some of the PUSCH layers into groups in which the transmission target data is the same between the layers. Based on the group information, the control unit 130 maps the transmission target data to at least some of the PUSCH layers so that the transmission target data is the same between at least some of the PUSCH layers. The control unit 130 selects one or more PUSCH groups from among the multiple PUSCH groups indicated by the group information, and selects, based on the selected PUSCH group, layers in which the transmission target data is the same between the layers of the PUSCH. That is, in the modification of the second embodiment, the UE 100 selects layers of the PUSCH in which the data to be transmitted is the same between the layers based on the group information. With this configuration, in the modification of the second embodiment, it is possible to suppress a decrease in the transmission efficiency of the data to be transmitted.

[0081] (2.1) System Operation Example A system operation example according to a modification of the second embodiment will be described with reference to Fig. 9, focusing on differences from the second embodiment. Fig. 9 is a diagram showing a system operation example according to a modification of the second embodiment. Note that the processes of steps S310, S330, S340, S360, S370, and S380 are similar to the processes of steps S210, S220, S230, S250, S260, and S270 in Fig. 8, and therefore will not be described again.

[0082] In step S320, the node 200 transmits the group information to the UE 100. The UE 100 receives the group information. Note that the node 200 may transmit the group information to the UE 100 immediately after the UE 100 starts up.

[0083] In one example of this embodiment, the group information indicates a PUSCH group of a layer among PUSCH layers in which the data to be transmitted is the same between the layers. In one example of this embodiment, the group information is information for selecting one or more PUSCH groups. In the group information, the PUSCH group is indicated, for example, by a set of layers. In this case, the group information indicates, for example, a first PUSCH group, a second PUSCH group, and a third PUSCH group. For example, the first PUSCH group indicates the first layer. The second PUSCH group indicates a set of the second layer and the third layer. The third PUSCH group indicates a set of the first layer, the second layer, and the third layer. The UE 100 selects one PUSCH group from the first PUSCH group, the second PUSCH group, or the third PUSCH group. The UE 100 maps the data to be transmitted to the layers so that the data to be transmitted is the same between the layers indicated by the selected PUSCH group. As another example, the first PUSCH group may indicate a pair of a first layer and a second layer, and the second PUSCH group may indicate a pair of a third layer and a fourth layer. In this case, the UE 100 selects one or more of the first PUSCH group and the second PUSCH group.

[0084] In the group information, the PUSCH group may be indicated by the number of layers. In this case, for example, the first PUSCH group indicates 1 as the number of layers. The second PUSCH group indicates 2 as the number of layers. The third PUSCH group indicates 3 as the number of layers. UE 100 selects one PUSCH group from the first PUSCH group, the second PUSCH group, or the third PUSCH group. UE 100 maps the data to be transmitted to the layers so that the data to be transmitted is the same between the layers for the number of layers indicated by the selected PUSCH group. In this case, the PUSCH group may be indicated by a set of SRIs or the number of SRIs. In addition, the PUSCH group may be referred to as an SRS group. The PUSCH group may also be referred to as a beam group.

[0085] In step S350, UE 100 transmits a PUSCH and an SRS to node 200. Here, UE 100 selects one PUSCH group from among a plurality of PUSCH groups indicated by the group information. UE 100 maps data to be transmitted to a layer of a PUSCH layer so that the data to be transmitted is the same between layers indicated by the selected PUSCH group among the PUSCH layers. In other words, UE 100 multiplexes the same data to be transmitted onto a portion of the PUSCH layers. In the example shown in FIG. 9, a second PUSCH group indicating a pair of a second layer and a third layer is selected. As a result, the same data to be transmitted is mapped to the second layer and the third layer.

[0086] The node 200 may transmit the group information to the UE 100 at any time before the UE 100 transmits the PUSCH. For example, the node 200 may transmit the group information to the UE 100 after the node 200 transmits the CSI-RS. That is, step S320 may be executed after step S330.

[0087] In addition, the PUSCH group indicated by the group information may include all layer sets. When the UE 100 selects the PUSCH group, similarly to the second embodiment, the UE 100 maps the transmission target data to the PUSCH layer so that the transmission target data is the same among all layers of the PUSCH layer.

[0088] In addition, the PUSCH group indicated by the group information may include a PUSCH group indicating only one layer. When the UE 100 selects the PUSCH group, the UE 100 maps the data to be transmitted to the multiple layers such that the data to be transmitted differs among the multiple layers of the PUSCH, as in the first embodiment.

[0089] In the modification of the second embodiment, various methods for mapping transmission target data to layers using a PUSCH group have been described. Which method is preferable for mapping transmission target data to layers is classified from the viewpoint of an application in which the transmission target data is used.

[0090] When data to be transmitted is mapped to multiple layers of a PUSCH so that the data to be transmitted is the same across all of the multiple layers, the PUSCH is preferably used to transmit data of an application that requires higher reliability and lower latency than transmitting large amounts of data at high speed. The data of the application is, for example, data used to control the application, or emergency notification or breaking news data.

[0091] When data to be transmitted is mapped to multiple layers of a PUSCH such that the data to be transmitted differs among all of the multiple layers, the PUSCH is preferably used to transmit data of an application that requires high-speed transmission of large amounts of data rather than high reliability, such as video or moving image data that requires large amounts of data and real-time performance.

[0092] When data to be transmitted is mapped to multiple layers of a PUSCH so that the data to be transmitted is the same among some of the multiple layers, this is preferably used when both high reliability and transmission efficiency are required. When both high reliability and transmission efficiency are required, there are cases where data of a single application that requires both high reliability and transmission efficiency is transmitted, and cases where data of multiple applications that each require both high reliability and transmission efficiency are transmitted simultaneously.

[0093] When transmitting data of a single application that requires both high reliability and transmission efficiency, for example, by mapping the same data to be transmitted to two layers, high reliability and transmission efficiency can be achieved at the same time. An example of a single application that requires both high reliability and transmission efficiency is a remote control application used at construction sites or medical sites. On the other hand, when simultaneously transmitting data of multiple applications that each require high reliability and transmission efficiency, for example, by mapping the same data to be transmitted to two layers out of a maximum of four layers and mapping different data to be transmitted to the remaining two layers, it is possible to achieve both the application that requires high reliability and the application that requires transmission efficiency.

[0094] In the above, the mapping of data to be transmitted to layers has been classified from the perspective of the application in which the data to be transmitted is used, but it can also be classified from the perspective of QoS or radio bearer (RB). When the QoS class identifiers (e.g., Quality Class Identifier (QCI), 5QI) of two logical transmission paths corresponding to a network slice (e.g., identified by S-NSSAI), a virtual communication path (e.g., PDU session), a QoS flow (QFI), a radio bearer, or an LCH (Logical Channel) indicate high reliability or the same QoS class identifier, for example, four layers are grouped into two PUSCH groups, and data of the two logical transmission paths is transmitted using each of the two PUSCH groups.

[0095] Furthermore, when the QoS class identifiers of three logical transmission paths corresponding to a network slice, a virtual communication path, a QFI, an RB, or an LCH are different from one another, data of a logical transmission path requiring high reliability and data of a logical transmission path that requires low reliability are transmitted using different numbers of layers. For example, data of a logical transmission path corresponding to a QoS class identifier indicating high reliability is mapped to a first PUSCH group indicating a pair of a first SRS and a second SRS. Data of a logical transmission path corresponding to a QoS class identifier indicating low reliability is mapped to a second PUSCH group indicating a third SRS. Data of a logical transmission path corresponding to a QoS class identifier indicating low reliability is mapped to a third PUSCH group indicating a fourth SRS.

[0096] In addition, the UE 100 may map data requiring high reliability in order from the layer with the best quality. The quality of the layer is determined based on the CSI-RS measurement result. Furthermore, the UE 100 may predict the reliability when a plurality of layers are combined and determine the optimal combination of layers. The reliability is evaluated, for example, by an error rate or the like, and predicted based on the CSI-RS measurement result. For example, the layer with the highest layer quality and the layer with the third highest layer quality may be combined to form a PUSCH group for satisfying high reliability (QoS).

[0097] (3) Third Embodiment With reference to FIG. 10 , the third embodiment will be described, mainly focusing on differences from the modified example of the second embodiment. In the modified example of the second embodiment described above, a case has been described in which the UE 100 selects, based on group information, layers of the PUSCH layers in which data to be transmitted is the same between layers. In the third embodiment, a case has been described in which the node 200 selects, based on group information, layers of the PUSCH layers in which data to be transmitted is the same between layers. In the third embodiment, the group information is information indicating layers belonging to a PUSCH group or the number of layers belonging to a PUSCH group. The receiving unit 110 receives group designation information that designates a PUSCH group from the node 200. The control unit 130 selects, based on the PUSCH group designated by the group designation information received from the node 200, layers of the PUSCH layers in which data to be transmitted is the same between layers.

[0098] (3.1) System Operation Example A system operation example according to the third embodiment will be described, focusing on differences from the modified example of the second embodiment, with reference to Fig. 10. Fig. 10 is a diagram showing a system operation example according to the third embodiment. Note that the processes of steps S410, S430, S440, and S450 are similar to the processes of steps S110 and S120 in Fig. 7 and steps S30 and S40 in Fig. 4, and therefore will not be described here.

[0099] In step S420, the node 200 transmits the group information to the UE 100. The node 200 transmits the group information to the UE 100, for example, at an RRC layer. Note that the node 200 may transmit the group information to the UE 100 at a MAC layer, or may transmit the group information to the UE 100 by including it in DCI. The UE 100 receives the group information.

[0100] In this embodiment, in the group information, the PUSCH group is indicated by a set of SRIs. Note that in the group information, the PUSCH group may be indicated by the number of SRIs. Also, in the group information, the PUSCH group may be indicated by the number of layers. Also, in the group information, the PUSCH group may be indicated by a set of layers.

[0101] In step S460, the node 200 determines one or more SRIs corresponding to a precoder used for transmitting the PUSCH based on the received SRS. Here, the node 200 determines one or more SRIs for transmitting data of each logical transmission path based on an index indicating the quality of the logical transmission path (Quality of Service: QoS).

[0102] In step S470, the node 200 transmits the DCI to the UE 100. The node 200 transmits the DCI to the UE 100, for example, on the PDCCH. Note that the node 200 may transmit the DCI to the UE 100 on the MAC layer. The UE 100 receives the DCI.

[0103] The DCI includes one or more SRIs determined by node 200. Here, the one or more SRIs are stored in an SRS resource indicator field included in the DCI. The DCI also includes group designation information. The group designation information is information that designates a PUSCH group from among the PUSCH groups indicated by the group information. Note that the DCI may also include radio resource allocation information. The radio resource allocation information is, for example, an UL grant (PUSCH radio resource allocation information).

[0104] In step S480, the UE 100 transmits the PUSCH and the SRS to the node 200. Here, the UE 100 selects one PUSCH group indicated by the group designation information from among the multiple PUSCH groups indicated by the group information.

[0105] In step S480, UE 100 transmits a PUSCH to node 200 using the same antenna port as the antenna port of the SRS. The antenna port of the SRS is indicated by one or more received SRIs. As a result, the same precoder as that of the SRS of the SRS resource indicated by the received SRI is applied to the transmission of the PUSCH. Here, UE 100 maps the data to be transmitted to the layer of the PUSCH so that the data to be transmitted is the same between layers indicated by the selected PUSCH group among the PUSCH layers. The PUSCH group is the PUSCH group selected by UE 100 based on the group designation information.

[0106] (3.2) First Modification of Third Embodiment The first modification of the third embodiment will be described with reference to Fig. 11, focusing on the differences from the third embodiment. In the first modification of the third embodiment, the group information is information indicating the association between layers belonging to a PUSCH group and logical transmission paths, or the association between the number of layers belonging to a PUSCH group and logical transmission paths. The control unit 130 selects, from among the PUSCH layers, layers in which the data to be transmitted is the same between the layers, based on the PUSCH group associated with the logical transmission paths by the group information.

[0107] (3.3) System Operation Example A system operation example according to the first modified example of the third embodiment will be described with reference to Fig. 11, focusing on differences from the third embodiment. Fig. 11 is a diagram showing a system operation example according to the first modified example of the third embodiment. Note that the processes of steps S510, S530, S540, S550, and S560 are similar to the processes of steps S410, S430, S440, S450, and S460 in Fig. 10, and therefore will not be described again.

[0108] In step S520, the node 200 transmits group information to the UE 100. The UE 100 receives the group information. In a first modification of the third embodiment, the content indicated by the group information differs from that of the third embodiment. In the first modification of the third embodiment, in the group information, a PUSCH group is indicated by a set of SRIs, and the PUSCH group is linked to a logical transmission path. The logical transmission path is specified by, for example, a logical channel identifier (LCID) or a data radio bearer identifier (DRB ID). Note that in the group information, a PUSCH group may be indicated by the number of SRIs, and the PUSCH group may be linked to a logical transmission path.

[0109] In step S570, the node 200 transmits the DCI to the UE 100. The UE 100 receives the DCI. In a first modification of the third embodiment, the DCI does not include group designation information. Note that the DCI may include group designation information.

[0110] In step S580, UE 100 transmits a PUSCH and an SRS to node 200. Here, UE 100 selects one PUSCH group linked to a logical transmission path from among the multiple PUSCH groups indicated by the group information. UE 100 determines the logical transmission path based on, for example, the LCID included in the DCI received in step S570. UE 100 maps the data to be transmitted to a layer of the PUSCH so that the data to be transmitted is the same between layers indicated by the selected PUSCH group among the PUSCH layers.

[0111] (3.4) Second Modification of Third Embodiment The second modification of the third embodiment will be described with reference to Fig. 12, focusing on differences from the first modification of the third embodiment. In the second modification of the third embodiment, the group information is information indicating an association between layers belonging to a PUSCH group and radio resources, or an association between the number of layers belonging to a PUSCH group and radio resources. The control unit 130 selects, from among the PUSCH layers, layers in which the data to be transmitted is the same between the layers, based on the PUSCH group associated with the radio resources by the group information.

[0112] (3.5) System Operation Example A system operation example according to the second modified example of the third embodiment will be described with reference to Fig. 12, focusing on differences from the first modified example of the third embodiment. Fig. 12 is a diagram showing a system operation example according to the second modified example of the third embodiment. Note that the processes of steps S610, S630, S640, S650, S660, and S670 are similar to the processes of steps S510, S530, S540, S550, S560, and S570 in Fig. 11, and therefore will not be described again.

[0113] In step S620, the node 200 transmits group information to the UE 100. The UE 100 receives the group information. In a second modification of the third embodiment, the content indicated by the group information differs from that of the first modification of the third embodiment. In the second modification of the third embodiment, in the group information, the PUSCH group is indicated by the number of SRIs, and the PUSCH group is linked to a radio resource. The radio resource is specified by, for example, a radio bearer (RB), a frequency band, or a frequency range (FR). Note that in the group information, the PUSCH group may be indicated by a set of SRIs, and the PUSCH group may be linked to a radio resource.

[0114] In step S680, UE 100 transmits a PUSCH and an SRS to node 200. Here, UE 100 selects one PUSCH group linked to radio resources from among a plurality of PUSCH groups indicated by the group information. UE 100 maps data to be transmitted to a layer of the PUSCH such that data to be transmitted is the same between layers indicated by the selected PUSCH group among the PUSCH layers.

[0115] Note that in the group information, the associations between the PUSCH group and various pieces of information in the group information described in the above-described third embodiment, the first modification of the third embodiment, and the second modification of the third embodiment may be combined. For example, in the group information, the PUSCH group may be indicated by a combination of a logical transmission channel and a set of SRIs. As another example, in the group information, the PUSCH group may be indicated by a combination of a logical transmission channel and the number of SRIs. As another example, in the group information, the PUSCH group may be indicated by a combination of a radio resource, a logical transmission channel, and the number of SRIs.

[0116] (3.6) Third Modification of Third Embodiment With reference to Fig. 13, the third modification of the third embodiment will be described, mainly focusing on the differences from the third embodiment. In the third modification of the third embodiment, the group information is information that specifies one or more PUSCH groups. Based on the PUSCH group indicated by the group information, the control unit 130 maps the data to be transmitted to at least some of the PUSCH layers so that the data to be transmitted is the same between at least some of the PUSCH layers.

[0117] (3.7) System Operation Example A system operation example according to the third modified example of the third embodiment will be described with reference to Fig. 13, focusing on differences from the third embodiment. Fig. 13 is a diagram showing a system operation example according to the third modified example of the third embodiment. Note that the processes of steps S710, S720, S730, S740, and S750 are similar to the processes of steps S410, S430, S440, S450, and S460 in Fig. 10, and therefore will not be described again.

[0118] In step S760, the node 200 transmits the DCI to the UE 100. The node 200 transmits the DCI to the UE 100, for example, on the PDCCH. Note that the node 200 may transmit information corresponding to the DCI to the UE 100 in the MAC layer. The UE 100 receives the DCI.

[0119] The DCI includes one or more SRIs determined by the node 200. The DCI also includes group information and radio resource allocation information. In a third modification of the third embodiment, the group information indicates, for example, the number of layers in which the data to be transmitted is the same between the layers. Note that the group information may also indicate a set of layers in which the data to be transmitted is the same between the layers.

[0120] In step S770, the UE 100 transmits the PUSCH and the SRS to the node 200. Here, the UE 100 maps the data to be transmitted to the layer of the PUSCH so that the data to be transmitted is the same between the layers indicated by the group information.

[0121] As described above, in the third embodiment and the first, second, and third modifications of the third embodiment, unlike the first embodiment, the second embodiment, and the modifications of the second embodiment described above, when the UE 100 transmits to the node 200 an SRS for the node 200 to determine one or more SRIs, the UE 100 does not transmit a PUSCH to the node 200. For example, in step S450 in FIG. 10 , similar to step S40 in FIG. 4 , the UE 100 transmits an SRS to the node 200 but does not transmit a PUSCH to the node 200. In the third embodiment and the first, second, and third modifications of the third embodiment as well, the UE 100 may transmit a PUSCH to the node 200 together with an SRS, for example, in step S450 in FIG. 10 . In this case, similar to the first embodiment, the second embodiment, and the modified example of the second embodiment, UE100 transmits to node 200 an SRS to which a precoder calculated by UE100 has been applied, and a PUSH to which a precoder calculated by UE100 has been applied.

[0122] According to the above-described second embodiment, the modified example of the second embodiment, and the third embodiment, the first modified example, the second modified example, and the third modified example of the third embodiment, the UE 100 performs wireless communication with the node 200 in a mobile communication system. The control unit 130 maps data to be transmitted to at least some of the layers of the PUSCH so that the data to be transmitted is the same between at least some of the layers of the PUSCH. The transmission unit 120 transmits the PUSCH to the node 200.

[0123] A program may be provided that causes a computer (UE 100, node 200) to execute the operations according to the above-described embodiments. The program may be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0124] One embodiment of the present invention has been described in detail above with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes and the like are possible within the scope that does not deviate from the gist of the present invention.

[0125] 1 Network 10 RAN 20 CN 100 UE 110 Receiving unit 120 Transmitting unit 130 Control unit 140 Wireless communication unit 200 Node 210 Transmitting unit 220 Receiving unit 230 Control unit 240 NW communication unit 250 Wireless communication unit 300 CN device

Claims

1. A user equipment that performs wireless communication with a node in a mobile communication system, comprising: a receiving unit that receives a first reference signal transmitted by the node; a control unit that measures resources of the first reference signal, calculates a precoder to be used for transmitting a first physical uplink shared channel based on the measured resources of the first reference signal, and applies the precoder to the first physical uplink shared channel; and a transmitting unit that transmits the first physical uplink shared channel to which the precoder has been applied to the node, wherein the control unit maps the first data to be transmitted to multiple layers of the first physical uplink shared channel such that the first data to be transmitted differs among the multiple layers.

2. The user equipment according to claim 1, wherein the control unit maps second data to be transmitted, which is different from the first data to be transmitted, to a second physical uplink shared channel that is transmitted after the first physical uplink shared channel to which the transmission unit has applied the precoder.

3. The user equipment according to claim 1, wherein the control unit determines the number of layers of the first physical uplink shared channel based on measurement of resources of the first reference signal.

4. The user equipment according to claim 3, wherein the control unit calculates a precoder to be used for transmitting a second reference signal based on measurement of resources of the first reference signal, selects antenna ports for the number of layers from antenna ports for the second reference signal, and uses the selected antenna ports for the number of layers for transmitting the first physical uplink shared channel.

5. A node that performs wireless communication with a user device in a mobile communication system, comprising: a transmitter that transmits a first reference signal to the user device; and a receiver that receives from the user device a first physical uplink shared channel that the user device transmitted by applying a precoder calculated based on measurement of resources of the first reference signal, wherein first data to be transmitted is mapped to multiple layers of the first physical uplink shared channel so that the first data to be transmitted differs among the multiple layers.

6. A communication method used by a user equipment that performs wireless communication with a node in a mobile communication system, comprising: a step of receiving a first reference signal transmitted by the node; a step of measuring a resource of the first reference signal, calculating a precoder to be used for transmitting a first physical uplink shared channel based on the measurement of the resource of the first reference signal, and applying the precoder to the first physical uplink shared channel; and a step of transmitting the first physical uplink shared channel to which the precoder has been applied to the node, wherein the first data to be transmitted is mapped to the multiple layers of the first physical uplink shared channel such that the first data to be transmitted differs among the multiple layers.

7. A communication method used in a node that performs wireless communication with a user equipment in a mobile communication system, comprising: a step of transmitting a first reference signal to the user equipment; and a step of receiving from the user equipment a first physical uplink shared channel that the user equipment transmitted by applying a precoder calculated based on measurement of resources of the first reference signal, wherein the first data to be transmitted is mapped to a plurality of layers of the first physical uplink shared channel so that the first data to be transmitted differs among the plurality of layers.

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