Terminal device and wireless communication method

Abstract

Provided is a terminal device (10) that is capable of wireless communication with a plurality of base station devices (50), the terminal device (10) comprising: an acceptance unit (11) that accepts an enquiry regarding capability information of the terminal device (10) from one base station device among the plurality of base station devices (50); a notification unit (13) which, in a case in which the terminal device (10) is capable of communicating with the plurality of base station devices (50) arranged at different positions, issues, to the one base station device and on the basis of the enquiry, notification of, as capability information, usability information indicating that the terminal device (10) is capable of using a plurality of MIMO methods having different maximum numbers of usable layers; and a reception unit (15) that receives a wireless signal transmitted by the one base station device by using a MIMO method set on the basis of the capability information. As a result thereof, it possible to provide wireless communication technology for improving the usage efficiency of wireless communication resources between the terminal device (10) and the base station devices (50).

Description

Terminal device and wireless communication method

[0001] The present invention relates to a terminal device and a wireless communication method.

[0002] The international standardization organization 3GPP (Third Generation Partnership Project) (registered trademark) is studying New Radio (NR), a new radio access technology for fifth-generation (5G) cellular communication systems. NR is being considered as a technology that will enable a wider variety of services than the fourth-generation cellular communication system, Long Term Evolution (LTE)-Advanced. For example, NR defines different usage scenarios as realization requirements, such as eMBB (enhanced Mobile Broadband), which realizes high-speed, large-capacity communication; URLLC (Ultra-Reliable and Low Latency Communication), which realizes ultra-reliable, low-latency communication; and mMTC (massive Machine Type Communication), which realizes simultaneous connection of multiple Internet of Things (IoT) devices.

[0003] NR employs carrier aggregation (CA), which enables bandwidth expansion by aggregating multiple frequency bands, for example, 20 MHz, called component carriers (CCs) (see Non-Patent Document 1). NR also employs E-UTRA-NR Dual Connectivity (EN-DC), which uses base station devices eNBs (evolved NodeBs) in E-UTRA (Evolved Universal Terrestrial Radio Access) and base station devices gNBs (g-NodeBs) in NR (see Non-Patent Document 2). Regarding EN-DC, two known scenarios are known: a collocated scenario in which eNBs and gNBs located in the same location communicate with a terminal device, and a non-collocated scenario in which eNBs and gNBs located in different locations communicate with a terminal device.

[0004] In NR, in Intra-band EN-DC and Intra-band NR CA, the terminal device supports a co-location scenario as a Type 1 UE. Also, in Intra-band EN-DC, the terminal device supports a non-co-location scenario in which a 2x2 MIMO scheme (maximum number of usable MIMO layers is 2) can be used for each CC as a Type 2 UE (see Non-Patent Document 3). In this case, a terminal device (Type 2 UE) that supports the non-co-location scenario notifies the base station device of this by including it in the terminal device's terminal capability information "UECapabilityInformation" (see Non-Patent Document 1). Note that in Intra-band NR CA, the terminal device does not support such a non-co-location scenario.

[0005] 3GPP standards “TS 38.306 Ver.16.7.0 (2021-12)” 3GPP standards “TS 37.340 Ver.16.8.0 (2021-12)” 3GPP standards “TS 38.133 Ver.17.5.0 (2022-04)”

[0006] In conventional wireless communication systems, as described above, a terminal device that supports a non-co-location scenario in which a 2x2 MIMO scheme can be used for each CC is simply notified to a base station device by including this information in the terminal capability information of the terminal device.

[0007] However, in NR, there is no mechanism for a base station device to check whether a terminal device can use multiple MIMO schemes with different maximum numbers of MIMO layers. That is, even if a terminal device can use a 4x4 MIMO scheme (maximum number of usable MIMO layers is 4) in addition to a 2x2 MIMO scheme, conventional communication methods cannot perform appropriate scheduling according to the MIMO scheme usable by the terminal device. Therefore, there is a risk that the utilization efficiency of wireless communication resources between the terminal device and the base station device will decrease.

[0008] The present invention has been made in view of the above circumstances, and has an object to provide a wireless communication technique for improving the utilization efficiency of wireless communication resources between a terminal device and a base station device.

[0009] A terminal device according to one aspect of the present invention is a terminal device capable of wireless communication with a plurality of base station devices, and includes: a reception unit that receives an inquiry regarding capability information of the terminal device from one of the plurality of base station devices; a notification unit that, if the terminal device is capable of communicating with a plurality of base station devices located at different locations, notifies the one base station device of usability information indicating that the terminal device can use a plurality of MIMO methods with different maximum numbers of layers usable as capability information based on the inquiry; and a reception unit that receives a radio signal transmitted by the one base station device using the MIMO method set based on the capability information.

[0010] A wireless communication method according to one aspect of the present invention is a wireless communication method executed by a terminal device capable of wireless communication with a plurality of base station devices, and includes receiving an inquiry regarding capability information of the terminal device from one of the plurality of base station devices, and if the terminal device is capable of communicating with a plurality of base station devices located at different locations, notifying the one base station device of usability information indicating that the terminal device is capable of using a plurality of MIMO methods with different maximum numbers of layers usable by the terminal device based on the inquiry, as capability information, and receiving a wireless signal transmitted by the one base station device using the MIMO method set based on the capability information.

[0011] According to the present invention, it is possible to provide a wireless communication technique for improving the utilization efficiency of wireless communication resources between a terminal device and a base station device.

[0012] FIG. 1 is a configuration diagram showing an example of a schematic configuration of a wireless communication system in an embodiment. FIG. 2 is a configuration diagram showing an example of a hardware configuration of a terminal device and a base station device in an embodiment. FIG. 3 is a configuration diagram showing an example of a functional block configuration of a terminal device in an embodiment. FIG. 4 is a configuration diagram showing an example of a functional block configuration of a base station device in an embodiment. FIG. 5 is a flowchart showing an example of a wireless signal transmission process of a terminal device in an embodiment. FIG. 6 is a flowchart showing an example of a wireless signal transmission process of a terminal device in an embodiment. FIG. 7 is a flowchart showing an example of a wireless signal transmission process of a terminal device in an embodiment. FIG. 8 is a flowchart showing an example of a wireless signal transmission process of a terminal device in an embodiment.

[0013] An embodiment of the present invention will be described below. In the following description of the drawings, identical or similar parts are denoted by identical or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Furthermore, it goes without saying that the drawings include parts with different dimensional relationships and ratios. Furthermore, the technical scope of the present invention should not be interpreted as being limited to the embodiment.

[0014] A schematic configuration of a wireless communication system according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of the schematic configuration of a wireless communication system 100. The wireless communication system 100 includes terminal devices 10-1 to 10-m, base station devices 50-1 to 50-n, and a core network device 90.

[0015] The wireless communication system 100 is, for example, a wireless communication system that targets NR (New Radio). Note that the present invention is applicable to any wireless communication system that includes at least a terminal device and a base station device, and is not limited to those that target NR. For example, the present invention is also applicable to LTE and LTE-Advanced. It is also applicable to wireless communication systems that use NR as part of the wireless communication system.

[0016] Hereinafter, LTE and LTE-Advanced are also referred to as E-UTRA (Evolved Universal Terrestrial Radio Access). An area (coverage area) formed by a base station device is called a cell, and E-UTRA and NR are cellular communication systems constructed by multiple cells. The wireless communication system according to this embodiment may apply either TDD (Time Division Duplex) or FDD (Frequency Division Duplex), or different methods may be applied to each cell.

[0017] Each of the terminal devices 10-1 to 10-m is wirelessly connected to one of the base station devices 50-1 to 50-n. Furthermore, each of the terminal devices 10-1 to 10-m may be wirelessly connected to two or more of the base station devices 50-1 to 50-n simultaneously. Each of the base station devices 50-1 to 50-n can use E-UTRA or NR. For example, the base station device 50-1 may use NR and the base station device 50-n may use E-UTRA, or vice versa. A base station device in E-UTRA is called an eNB (evolved NodeB), and a base station device in NR is called a gNB (g-NodeB).

[0018] The wireless communication system 100 is a wireless communication system that supports, for example, carrier aggregation (CA) and E-UTRA-NR Dual Connectivity (EN-DC). Carrier aggregation refers to a process that enables bandwidth expansion by aggregating (bundling) multiple frequency bands, for example, 20 MHz, called component carriers (CC).

[0019] In EN-DC (E-UTRA-NR Dual Connectivity), a base station device eNB and a base station device gNB can cooperate to communicate with a terminal device 10. For example, a scenario in which an eNB and a gNB located in the same position communicate with a terminal device 10 is called a collocated scenario, and a scenario in which an eNB and a gNB located in different positions communicate with a terminal device 10 is called a non-collocated scenario.

[0020] Here, an overview of a wireless communication system 100 according to an embodiment of the present invention will be described below. NR employs antenna technology to improve wireless communication throughput. For example, NR is capable of wireless communication using millimeter waves. Performing wireless communication using a relatively high frequency band such as millimeter waves increases propagation loss and other problems. To prevent such problems, a technology known as beamforming is used to form beams with a relatively narrow beam width. NR also employs MIMO (Multiple Input Multiple Output), a technology in which both the transmitting and receiving sides are equipped with multiple antennas and transmit data in parallel by dividing it among the multiple antennas.

[0021] Assuming this MIMO technology, as described above, in conventional wireless communication systems, a 2x2 MIMO scheme (the maximum number of usable MIMO layers is 2) can be used for each component carrier CC, and a terminal device that supports a non-co-location scenario simply notifies the base station device of this (for example, information IA) by including this information in the terminal device's terminal capability information "UECapabilityInformation." [Information IA] intraBandMRDC-WithOverlapDL-Bands-r16 :: = {Supported} Note that the 2x2 MIMO scheme is a scheme in which two antennas are used on the transmitting side (base station device) and the receiving side (terminal device).

[0022] However, in conventional wireless communication systems, there is no mechanism for a base station device to check whether a terminal device can use multiple MIMO schemes with different maximum numbers of usable MIMO layers. That is, in conventional wireless communication systems, even if a terminal device can use a 4x4 MIMO scheme (with a maximum number of usable MIMO layers of 4) in addition to a 2x2 MIMO scheme, only the 2x2 MIMO scheme is adopted. Therefore, conventional communication techniques cannot perform appropriate scheduling according to the MIMO scheme usable by the terminal device. This may result in a decrease in the utilization efficiency of wireless communication resources between the terminal device and the base station device. Here, the 4x4 MIMO scheme is a scheme in which the transmitting side (base station device) and the receiving side (terminal device) each use four antennas.

[0023] Therefore, in an embodiment of the present invention, a terminal device is capable of wireless communication with multiple base station devices, and receives an inquiry about capability information of the terminal device from one of the multiple base station devices. When the terminal device can communicate with multiple base station devices located at different locations (for example, when the terminal device supports a non-co-location scenario), the terminal device notifies the one base station device of usability information indicating that the terminal device can use multiple MIMO schemes with different maximum numbers of layers, based on the inquiry from the base station device. The terminal device receives a radio signal transmitted by the one base station device using the MIMO scheme set based on the capability information.

[0024] In this way, the base station device can set the MIMO method to be used in wireless communication with the terminal device based on the capability information of the terminal device, and perform appropriate scheduling according to the MIMO method.The terminal device can then receive wireless signals based on the wireless resources appropriately allocated from the base station device.This makes it possible to improve the utilization efficiency of wireless communication resources between the terminal device and the base station device.As a result, the technology according to this embodiment can contribute to achieving Goal 9 of the Sustainable Development Goals (SDGs), "Build resilient infrastructure and promote inclusive and sustainable industrialization," which is to "build inclusive and sustainable industrialization and promote inclusive and sustainable industrialization."

[0025] Below, each component of the wireless communication system 100 will be described in more detail. FIG. 1 illustrates terminal device 10-1 to terminal device 10-m as m terminal devices (m is an integer of 2 or more). In the following description, when describing these m terminal devices without distinguishing between them, some of the reference numerals will be omitted and they will simply be referred to as "terminal device 10." Also, FIG. 1 illustrates base station device 50-1 to base station device 50-n as n base station devices (n is an integer of 2 or more). In the following description, when describing these n base station devices without distinguishing between them, some of the reference numerals will be omitted and they will simply be referred to as "base station device 50." A terminal device in E-UTRA and NR is called UE (User Equipment). A base station device gNB in ​​NR may connect to a terminal device using a part of the frequency band it uses (BWP: Carrier Bandwidth Part). Hereinafter, when referring to a cell, it is assumed that the BWP is included.

[0026] Examples of the communication terminal 10 include portable information and communication devices such as IoT devices, smartphones, mobile phones, personal digital assistants (PDAs), tablet devices, portable game consoles, portable music players, and wearable devices. The terminal device 10 may be connected to a base station device 50 on a cell-by-cell basis, and may be connected using multiple cells, e.g., carrier aggregation. When the terminal device 10 is connected via multiple base station devices, i.e., in the case of DC (Dual Connectivity), the base station device initially connected is called a master node (MN), and additionally connected base station devices are called secondary nodes (SN). The base station devices are connected to each other via a base station interface. The base station device 50 and the core network device 90 are connected via a core interface. The base station interface is used to exchange control signals necessary for handover and cooperative operations between base station devices.

[0027] The core network device 90, for example, has the base station device 50 under its control, and mainly handles load control between base station devices, calling (paging) of the terminal device 10, location registration, and other mobility control. In NR, the core network device 90 defines an Access and Mobility Management Function (AMF) that manages mobility and a Session Management Function (SMF) that manages sessions as a group of control plane (C-plane) functions. In E-UTRA, an MME (Mobility Management Entity) corresponding to the AMF is defined.

[0028] 1 shows an example in which the core network device 90 is configured as a single device, but the present invention is not limited to this. For example, the core network device may be configured as multiple devices, including a server, a gateway, etc.

[0029] The terminal device 10 and the base station device 50 transmit and receive RRC messages in the Radio Resource Control (RRC) layer, and proceed with session processing (also referred to as a connection sequence). As the session processing proceeds, the terminal device 10 changes from an idle state (RRC Idle) to a connected state (RRC Connected) to the base station device 50. The idle state corresponds to a standby state of the terminal device 10.

[0030] Furthermore, the terminal device 10 and the base station device 50 transmit and receive MAC control elements (MAC CEs) in the Medium Access Control (MAC) layer. RRC messages are transmitted as RRC Protocol Data Units (PDUs). A common control channel (CCCH), a dedicated control channel (DCCH), a paging control channel (PCCH), a broadcast control channel (BCCH), or a multicast control channel (MCCH) is used as a logical channel to be mapped. A MAC CE is transmitted as a MAC PDU (or MAC subPDU). A MAC subPDU is equivalent to a service data unit (SDU) in the MAC layer plus, for example, an 8-bit header, and a MAC PDU includes one or more MAC subPDUs.

[0031] The following describes physical channels and physical signals related to an embodiment of the present invention. Among the physical channels related to the embodiment of the present invention, a physical broadcast channel (PBCH), a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical random access channel (PRACH), and a physical downlink control channel (PDCCH) will be described below.

[0032] In addition, in the wireless communication system according to the embodiment, there are at least a physical uplink control channel (PUCCH), a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), a scheduling reference signal (SRS), and a demodulation reference signal (DMRS), but detailed description thereof will be omitted.

[0033] <Physical Broadcast Channel (PBCH)> The Physical Broadcast Channel (PBCH) is transmitted from the base station device 50 to the terminal device 10, and is used to notify common parameters (system information) in the cell under the control of the base station device 50. The system information is further classified into a Master Information Block (MIB) and a System Information Block (SIB). The System Information Block is further subdivided into SIB1, SIB2, ... and transmitted.

[0034] The system information includes information necessary for connecting to a cell, and for example, the MIB includes a system frame number, information indicating whether camping on to a cell is possible, etc. Also, the SIB1 includes parameters for calculating the quality of a cell (cell selection parameters), cell-common channel information (random access control information, PUCCH control information, PUSCH control information), scheduling information of other system information, etc.

[0035] The Physical Broadcast Channel (PBCH) is periodically transmitted as a synchronization signal block (SSB: Synchronization Signal Block (or SS / PBSH)) in combination with a synchronization signal consisting of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). By receiving the synchronization signal block (SSB), the terminal device 10 can acquire cell identifier (cell ID) information and reception timing, as well as measure the quality of the signal of the cell.

[0036] System information notified by a physical broadcast channel (PBCH) or the like is also called "system broadcast information" or "broadcast information." Camping on a cell refers to a state in which the terminal device 10 completes cell selection and / or cell reselection and selects a cell for monitoring system broadcast information and paging information. The terminal device 10 establishes the above-mentioned RRC connection with the base station device 50 that forms the camped-on cell.

[0037] <Primary Synchronization Signal (PSS)> The primary synchronization signal (PSS) is used by the terminal device 10 to synchronize with the reception symbol timing and frequency of the downlink signal of the base station device 50. The primary synchronization signal (PSS) is the signal that the terminal device 10 first attempts to detect in the procedure for detecting the cell of the base station device 50 (hereinafter also referred to as the "cell search procedure"). The primary synchronization signal (PSS) repeatedly uses three signals, "0" to "2", based on the physical cell ID. Note that the physical cell ID is an identifier of a physical cell, and 504 different IDs are used in E-UTRA, while 1008 different IDs are used in NR.

[0038] <Secondary Synchronization Signal (SSS)> The secondary synchronization signal (SSS) is used by the terminal device 10 to detect the physical ID of the base station device 50. Specifically, the secondary synchronization signal (SSS) is a signal that the terminal device 10 uses to detect a physical cell ID in a cell search procedure. The secondary synchronization signal (SSS) repeatedly uses 168 different signals from "0" to "167" in E-UTRA and 336 different signals from "0" to "335" in NR based on the physical cell ID.

[0039] <Physical Random Access Channel (PRACH)> The physical random access channel (PRACH) is used by the terminal device 10 to transmit a random access preamble to the base station device 50. The physical random access channel (PRACH) is generally used in a state where uplink synchronization is not established between the terminal device 10 and the base station device 50, and is used for transmission timing adjustment information (timing advance) and uplink radio resource requests. Information indicating the radio resources available for transmitting the random access preamble is transmitted to the terminal using broadcast information or an RRC message.

[0040] <Physical Downlink Control Channel (PDCCH)> The Physical Downlink Control Channel (PDCCH) is transmitted from the base station device 50 to the terminal device 10 to notify the terminal device 10 of downlink control information (DCI). The downlink control information includes uplink radio resource information (uplink grant (UL grant)) that the terminal device 10 can use, or downlink radio resource information (downlink grant (DL grant)). The downlink grant is information indicating the scheduling of the Physical Downlink Shared Data Channel (PDSCH). The uplink grant is information indicating the scheduling of the Physical Uplink Shared Channel (PUSCH). When the Physical Downlink Control Channel (PDCCH) is transmitted in response to a random access preamble, the Physical Downlink Shared Data Channel (PDSCH) indicated by the Physical Downlink Control Channel (PDCCH) is a random access response, and includes index information of the random access preamble, transmission timing adjustment information, an uplink grant, etc.

[0041] <Hardware Configuration> The hardware configuration of the terminal device and the base station device in one embodiment will be described with reference to Fig. 2. Fig. 2 is a configuration diagram showing an example of the hardware configuration of the terminal device 10 and the base station device 50.

[0042] As shown in FIG. 2, the terminal device 10 and the base station device 50 each include, for example, a processor 21, a memory 22, a storage device 23, a communication device 24, an input device 25, an output device 26, an antenna 27, and a sensor 29.

[0043] The processor 21 is configured to control the operation of each part of the terminal device 10 or the base station device 50. The processor 21 is configured to include integrated circuits such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), an FPGA (Field Programmable Gate Array), and a SoC (System-on-a-chip).

[0044] The memory 22 and the storage device 23 are configured to store programs, data, etc. The memory 22 is configured, for example, by a read-only memory (ROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), and / or a random access memory (RAM), etc. The storage device 23 is configured, for example, by a storage device such as a hard disk drive (HDD), a solid state drive (SSD), and / or an embedded multi media card (eMMC).

[0045] The communication device 24 is configured to communicate via a wired and / or wireless network. The communication device 24 includes, for example, a network card, a communication module, etc. The communication device 24 also includes, for example, an amplifier, an RF (Radio Frequency) front end 243 that performs processing related to wireless signals, and a signal processing unit 241 that performs baseband signal processing.

[0046] The RF front end 243 generates a radio signal to be transmitted from the antenna 27 by, for example, performing D / A (Digital to Analog) conversion, modulation, frequency conversion, power amplification, etc. on the digital baseband signal received from the signal processing unit 241. The RF front end 243 also performs frequency conversion, demodulation, A / D (Analog to Digital) conversion, etc. on the radio signal received from the antenna 27 to generate a digital baseband signal and transmits it to the signal processing unit 241. The signal processing unit 241 performs a process of converting the digital baseband signal into an IP packet and a process of converting the IP packet into a digital baseband signal.

[0047] The input device 25 is configured to allow a user to input information through operations, and includes, for example, a keyboard, a touch panel, a mouse, and / or a microphone.

[0048] The output device 26 is configured to output information and includes a display device such as a liquid crystal display, an EL (Electro Luminescence) display, or a plasma display, and / or a speaker.

[0049] The antenna 27 is configured to emit and receive radio waves (electromagnetic waves) in one or more predetermined frequency bands. The antenna 27 may be a directional antenna. The gain of the directional antenna 27 varies depending on the orientation of the antenna. The antenna 27 may also be non-directional. The non-directional antenna 27 has approximately the same gain from all directions over 360 degrees in the horizontal plane, the vertical plane, or both the horizontal and vertical planes.

[0050] The antenna 27 is not limited to one. The terminal device 10 and the base station device 50 may be equipped with multiple antennas. As described above, the terminal device 10 and the base station device 50 each have multiple antennas so that the 2x2 MIMO system and the 4x4 MIMO system can be used. When the terminal device 10 and the base station device 50 have multiple antennas, for example, they may be divided into transmitting antennas and receiving antennas. Furthermore, when multiple antennas are divided into transmitting antennas and receiving antennas, at least one of them may include multiple antennas. Note that when the terminal device 10 and the base station device 50 have multiple transmitting / receiving antennas or transmitting antennas, the above-mentioned beamforming technology can be used.

[0051] The sensors 29 included in the terminal device 10 include sensors that detect the position, orientation, and acceleration of the terminal device 10. The sensors 29 included in the terminal device 10 include, for example, at least one of a GPS (Global Positioning System) sensor, a gyro sensor, and an acceleration sensor. On the other hand, the sensors 29 included in the base station device 50 may include, for example, sensors that detect environmental information such as temperature, humidity, weather, or seismic intensity in the base station device 50.

[0052] <Functional Block Configuration> (Terminal Device) The functional block configuration of the terminal device in this embodiment will be described with reference to Fig. 3. Fig. 3 is a configuration diagram showing an example of the functional block configuration of the terminal device 10. Note that Fig. 3 is intended to show the functional blocks necessary for explaining this embodiment, and does not exclude the terminal device 10 from including functional blocks other than those shown.

[0053] The terminal device 10 includes, as functional blocks, a reception unit 11, a notification unit 13, and a receiving unit 15, for example.

[0054] The reception unit 11 receives various information from the base station device 50 shown in Fig. 1. The reception unit 11 receives, for example, an inquiry from the base station device 50 regarding terminal capability information (capability information) of the terminal device 10. As shown in Figs. 5 to 8 described below, the terminal capability information includes, for example, "UECapabilityInformation," and the inquiry regarding the terminal capability information (capability information) includes "UECapabilityQuery."

[0055] The notification unit 13 notifies the base station device 50 of various information in response to an inquiry from the base station device 50. For example, the notification unit 13 responds (notifies) the base station device 50 with “UECapabilityInformation” based on “UECapabilityEnquiry” received from the base station device 50.

[0056] The notification unit 13 notifies the base station device 50 of usable information indicating that the terminal device 10 can use a plurality of MIMO schemes (e.g., a 2×2 MIMO scheme and a 4×4 MIMO scheme) with different maximum numbers of layers usable. The plurality of MIMO schemes are arbitrary and are not limited to the above-mentioned 2×2 MIMO scheme and 4×4 MIMO scheme, and may further include MIMO schemes with other maximum numbers of layers usable by the terminal device 10.

[0057] As will be described later, the "usable information" includes at least one of information regarding the maximum number of layers for each of a plurality of MIMO methods that differ in the maximum number of layers that can be used by the terminal device (information I1 shown in Figure 5), information indicating a plurality of MIMO methods that differ in the maximum number of layers that can be used by the terminal device (information I2 shown in Figure 6), and type information indicating that the terminal device 10 is a specific type of terminal device that can use a plurality of MIMO methods (information I3 shown in Figure 7 and information I4 shown in Figure 8).

[0058] The notification unit 13 may notify the base station device 50 of the availability information in any form as long as it can notify the base station device 50. The notification unit 13 is not limited to notifying the availability information as "UECapabilityInformation", and may notify the availability information as other information.

[0059] The receiving unit 15 receives a radio signal transmitted from the base station device 50. For example, the receiving unit 15 receives a radio signal transmitted by the base station device 50 using a MIMO scheme set based on terminal capability information. When a MIMO scheme suitable for the terminal capability of the terminal device 10 is set, the base station device 50 executes access control processing (e.g., CA processing and MIMO processing) for transmitting a radio signal to the terminal device 10. The receiving unit 15 receives the radio signal transmitted after the access control processing has been executed by the base station device 50.

[0060] The accepting unit 11, the notifying unit 13, and the receiving unit 15 may be realized by, for example, the communication device 24 shown in FIG. 2 , or may be realized by the communication device 24 and the processor 21 executing a program stored in the storage device 23. When the processor 21 executes a program, the program may be stored in a storage medium. The storage medium storing the program may be a non-transitory computer-readable medium. The non-transitory storage medium is not particularly limited, and may be, for example, a storage medium such as a USB (Universal Serial Bus) memory or a CD-ROM (Compact Disc ROM).

[0061] (Base Station Device) The functional block configuration of a base station device in this embodiment will be described with reference to Fig. 4. Fig. 4 is a configuration diagram showing an example of the functional block configuration of a base station device 50. Note that Fig. 4 is intended to show functional blocks necessary for explaining this embodiment, and does not exclude the base station device 50 from including functional blocks other than those shown.

[0062] The base station device 50 includes, as functional blocks, an inquiry unit 51, a setting unit 53, and a transmission unit 55, for example.

[0063] The inquiry unit 51 transmits a "UECapabilityQuery" to inquire about the terminal capability information "UECapabilityInformation" of the terminal device 10. The inquiry unit 51 receives the terminal capability information returned from the terminal device 10.

[0064] The setting unit 53 sets, for example, a MIMO layer of each CC during CA based on the terminal capability information of the terminal device 10 received by the inquiry unit 51. Furthermore, the setting unit 53 allocates, for example, radio resources for downlink CA processing to the terminal device 10 based on the terminal capability information of the terminal device 10 received by the inquiry unit 51.

[0065] The transmitter 55 transmits information about the MIMO layer of each CC during downlink CA set by the setting unit 53 as "RRC Reconfiguration" to the terminal device 10. In addition, the transmitter 55 executes access processing (e.g., CA processing and MIMO processing) for transmitting a radio signal from the base station device 50 to the terminal device 10.

[0066] The query unit 51, the setting unit 53, and the transmission unit 55 may be realized by, for example, the communication device 24 shown in FIG. 2 , or may be realized by the communication device 24 and the processor 21 executing a program stored in the storage device 23. When the processor 21 executes a program, the program may be stored in a storage medium. The storage medium storing the program may be a computer-readable non-transitory storage medium. The non-transitory storage medium is not particularly limited, and may be, for example, a storage medium such as a USB memory or a CD-ROM.

[0067] <Radio Signal Transmission Processing> (First Example) A first example of radio signal transmission processing of a terminal device according to an embodiment will be described with reference to FIG. 5 . The first example of radio signal transmission processing is an example in which, as a premise, multiple base station devices 50-1...50-n support a non-collocated scenario, and the terminal device 10 also supports the non-collocated scenario. Furthermore, an RRC connection is established between the terminal device 10 and the base station device 50. For example, the terminal device 10 and the base station device 50 transmit and receive RRC messages in the RRC layer, and proceed with session processing (also referred to as a connection sequence). The prerequisites in the first example of radio signal transmission processing described above also apply to a second example of radio signal transmission processing described later.

[0068] As shown in FIG. 5, for example, a base station device 50-1 (one of the base station devices) among the multiple base station devices 50 transmits a "UECapabilityQuery" to the terminal device 10 to inquire about the terminal capability information "UECapabilityInformation" of the terminal device 10 (step S1).

[0069] In response to the inquiry ("UECapabilityInquiry") from the base station device 50-1, the terminal device 10 returns (notifies) its own terminal capability information "UECapabilityInformation" to the base station device 50-1 (step S3A).

[0070] For example, the terminal device 10 notifies the base station device 50-1 of usable availability information indicating that the terminal device 10 can use a plurality of MIMO schemes (e.g., a 2x2 MIMO scheme and a 4x4 MIMO scheme) with different maximum numbers of layers usable. This usable availability information includes information I1 on the maximum number of layers for each of the plurality of MIMO schemes with different maximum numbers of layers usable by the terminal device 10. More specifically, the information I1 on the maximum number of layers for each of the plurality of MIMO schemes with different maximum numbers of layers usable by the terminal device 10 includes the following information shown in FIG. 5 .

[0071] [Information I1] intraBandMRDC-WithOverlapDL-Bands-maxNumberMIMO-LayersPDSCH :: = ENUMERATED {twoLayers, fourLayers} Here, "twoLayers" indicates the 2x2 MIMO scheme in which the maximum number of layers is 2, and "fourLayers" indicates the 4x4 MIMO scheme in which the maximum number of layers is 4. In other words, this information I1 indicates that the terminal device 10 supports the 2x2 MIMO scheme and the 4x4 MIMO scheme.

[0072] Based on the terminal capability information of the terminal device 10 received from the terminal device 10, the base station device 50-1 configures, for example, the MIMO layers of each CC during downlink CA and transmits (shares) the configured MIMO layers to other base station devices 50-n that support non-co-location scenarios (step S5). Because the terminal device 10 can use multiple MIMO schemes, including 2x2 MIMO and 4x4 MIMO, the base station device 50-1 can select the 4x4 MIMO scheme, which can further expand the communication bandwidth. The base station device 50-1 configures the MIMO layers for each CC based on the selected 4x4 MIMO scheme. Because the base station device 50-1 can communicate with other base station devices 50-n that support non-co-location scenarios, the base station device 50-1 transmits information regarding the configured MIMO layers of each CC during downlink CA to the other base station devices 50-n.

[0073] Next, the base station device 50-1 transmits information about the MIMO layer of each CC during the configured downlink CA to the terminal device 10 as "RRCReconfiguration" (step S7). In addition, the base station device 50-1 may allocate radio resources for the uplink based on the terminal capability information of the terminal device 10 received from the terminal device 10.

[0074] The base station device 50-1 may share the setting information with the other base station devices 50-n at any timing. The setting information may be transmitted to the other base station devices 50-n at each timing set and generated by the base station device 50-1, or may be transmitted in response to a request from the other base station devices 50-n.

[0075] The base station device 50-1 transmits a radio signal to the terminal device 10 using the set MIMO scheme (step S9). For example, the base station device 50-1 executes access control processing (e.g., CA processing and MIMO processing for downlink) for transmitting a radio signal to the terminal device 10. As described above, the base station device 50-1 shares setting information with the other base station devices 50-n. Therefore, the other base station devices 50-n can transmit a radio signal to the terminal device 10 using the MIMO scheme set by the base station device 50-1, just like the base station device 50-1.

[0076] As described above, according to the first example of the wireless signal transmission processing, the terminal device 10 receives an inquiry regarding terminal device capability information from one base station device 50-1 of the multiple base station devices 50. For example, if the terminal device 10 supports a non-co-location scenario, the terminal device 10 notifies the base station device 50-1 of usability information indicating that the terminal device 10 can use multiple MIMO schemes with different maximum numbers of layers, as terminal capability information, based on the inquiry from the base station device 50-1. In particular, in the first example of the wireless signal transmission processing, the terminal device 10 notifies the base station device 50-1 of information I1 regarding the maximum number of layers for each of the multiple MIMO schemes. The terminal device 10 receives a wireless signal transmitted by the base station device 50-1 using the MIMO scheme set based on the terminal capability information.

[0077] In this way, the base station device 50-1 can set an appropriate MIMO scheme to be used in wireless communication with the terminal device 10 based on information I1 regarding the maximum number of layers for each of multiple MIMO schemes that the terminal device 10 can use, and can perform appropriate scheduling according to the MIMO scheme.The terminal device 10 can then receive wireless signals transmitted based on wireless resources appropriately allocated from the base station device 50-1.This makes it possible to improve the utilization efficiency of wireless communication resources between the terminal device 10 and the multiple base station devices 50.

[0078] (Variation of the First Example) A variation of the first example of the radio signal transmission processing of the terminal device according to the embodiment will be described with reference to Fig. 6. In this variation of the first example of the radio signal transmission processing, the terminal device 10 notifies the base station device 50-1 of information indicating a plurality of MIMO methods with different maximum numbers of layers that the terminal device can use, as terminal capability information. Below, differences from the first example of the radio signal transmission processing will be particularly described.

[0079] 6, the terminal device 10 notifies the base station device 50-1 of information I2 indicating a plurality of MIMO schemes with different maximum numbers of layers that can be used by the terminal device 10 (step S3B). More specifically, the information I2 indicating a plurality of MIMO schemes with different maximum numbers of layers that can be used by the terminal device 10 includes the following information shown in FIG.

[0080] [Information I2] intraBandMRDC-WithOverlapDL-Bands-4Layers :: = ENUMERATED {Supported} Here, "...4Layers" indicates the 4x4 MIMO scheme, which has a maximum number of layers of 4. In other words, information I2 indicates that the terminal device 10 supports at least the 4x4 MIMO scheme. Furthermore, the fact that the terminal device 10 supports the 4x4 MIMO scheme indicates that it also supports the 2x2 MIMO scheme, which is a lower-level scheme than the 4x4 MIMO scheme. Therefore, this information I2 indicates that the terminal device 10 supports the 2x2 MIMO scheme and the 4x4 MIMO scheme.

[0081] According to the modified example of the first example of the radio signal transmission processing, the base station device 50-1 can set an appropriate MIMO method to be used in radio communication with the terminal device 10 based on information I2 indicating multiple MIMO methods with different maximum numbers of layers that the terminal device 10 can use, and can perform appropriate scheduling according to the MIMO method.The terminal device 10 can then receive radio signals transmitted based on radio resources appropriately allocated from the base station device 50-1.This makes it possible to improve the utilization efficiency of radio communication resources between the terminal device 10 and multiple base station devices 50.

[0082] (Second Example) A second example of the radio signal transmission process of the terminal device according to the embodiment will be described with reference to Fig. 7. In the second example of the radio signal transmission process, the terminal device 10 notifies the base station device 50-1 of type information indicating that the terminal device 10 is a specific type of terminal device that can use multiple MIMO schemes as terminal capability information. Below, differences from the first example of the radio signal transmission process will be particularly described.

[0083] 7, the terminal device 10 notifies the base station device 50-1 of type information I3 indicating that the terminal device 10 is a specific type of terminal device that can use multiple MIMO schemes (step S3C). More specifically, the type information I3 includes the following information shown in FIG.

[0084] [Information I3] intraBandMRDC-WithOverlapDL-Bands-r18 ::= {supported} Here, "intraBandMRDC-WithOverlapDL-Bands-r18" indicates a specific type of terminal device that can use a 4x4 MIMO scheme for each CC (in addition to a 2x2 MIMO scheme) and supports non-co-location scenarios. Also, "intraBandMRDC-WithOverlapDL-Bands-r18" is defined as new signaling, although it has the same signaling format as the conventional "intraBandMRDC-WithOverlapDL-Bands-r16" (conventional signaling), which indicates a terminal device that can use a 2x2 MIMO scheme for each CC and supports non-co-location scenarios.

[0085] According to the second example of the wireless signal transmission processing, the base station device 50-1 sets an appropriate MIMO scheme to be used in wireless communication with the terminal device 10 based on type information indicating that the terminal device is a specific type capable of using multiple MIMO schemes, and can perform appropriate scheduling according to the MIMO scheme. The terminal device 10 can then receive wireless signals transmitted based on wireless resources appropriately allocated from the base station device 50-1. This makes it possible to improve the utilization efficiency of wireless communication resources between the terminal device 10 and multiple base station devices 50. In particular, according to the second example, the wireless communication system 100 uses a signaling format similar to conventional signaling, but achieves the same effects as the first example by using new signaling.

[0086] (Variation of the Second Example) A variation of the second example of the wireless signal transmission processing of the terminal device according to the embodiment will be described with reference to Fig. 8. In the second example of the wireless signal transmission processing, new signaling is separately defined, while in the variation of the second example of the wireless signal transmission processing, changes are made to the content of conventional signaling. Below, differences from the second example of the wireless signal transmission processing will be particularly described.

[0087] 8, the terminal device 10 notifies the base station device 50-1 of type information 14 indicating that the terminal device 10 is a specific type of terminal device capable of using multiple MIMO schemes (step S3D). More specifically, the type information 14 includes the following information shown in FIG.

[0088] [Information I4] intraBandMRDC-WithOverlapDL-Bands-r16 :: = {Type 1, Type 2, Type 3} Here, "Type 3" (Type 3 UE) indicates a specific type of terminal device that can use the 4x4 MIMO scheme for each CC in addition to the 2x2 MIMO scheme and supports a non-co-location scenario. Note that "Type 1" (Type 1 UE) indicates a terminal device that supports a co-location scenario, and "Type 2" (Type 2 UE) indicates a terminal device that can use the 2x2 MIMO scheme for each CC and supports a non-co-location scenario.

[0089] In this way, the terminal device 10 can notify information I4 of a specific terminal device type "Type 3" in the conventional "intraBandMRDC-WithOverlapDL-Bands-r16", that is, information I4 that can use the 4x4 MIMO method for each CC and has a specific type added to support non-co-location scenarios.

[0090] According to the modified example of the second example of the wireless signal transmission processing, the base station device 50-1 sets an appropriate MIMO scheme to be used in wireless communication with the terminal device 10 based on type information indicating that the terminal device is a specific type capable of using multiple MIMO schemes, and can perform appropriate scheduling according to the MIMO scheme. The terminal device 10 can then receive wireless signals transmitted based on wireless resources appropriately allocated from the base station device 50-1. This makes it possible to improve the utilization efficiency of wireless communication resources between the terminal device 10 and multiple base station devices 50. In particular, according to the modified example of the second example, the wireless communication system 100 achieves the same effects as the first example by using signaling in which the content of conventional signaling is modified.

[0091] The above-described embodiments and examples are intended to facilitate understanding of the present invention and are not to be construed as limiting the present invention. The present invention may be modified or improved without departing from the spirit thereof, and equivalents thereof are also included in the present invention. Furthermore, the present invention can be formed into various disclosures by appropriately combining multiple components disclosed in the above-described embodiments or examples. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components may be appropriately combined in different embodiments.

[0092] 10 (10-1...10-m)...terminal device, 11...reception unit, 13...notification unit, 15...receiving unit, 21...processor, 22...memory, 23...storage device, 24...communication device, 25...input device, 26...output device, 27A, 27B...antenna, 29...sensor, 50 (50-1...50-n)...base station device, 51...inquiry unit, 53...setting unit, 55...transmission unit, 90...core network device, 100...wireless communication system,

Claims

1. A terminal device capable of wireless communication with a plurality of base station devices, a reception unit that receives an inquiry regarding capability information of the terminal device from one of the plurality of base station devices; a notification unit that notifies the one base station device of usability information indicating that the terminal device can use a plurality of MIMO schemes having different maximum numbers of layers usable therein, based on the inquiry, when the terminal device is capable of communicating with the plurality of base station devices located at different positions; and a receiving unit that receives a radio signal transmitted by the one base station device using a MIMO scheme set based on the capability information; A terminal device comprising:

2. The notification unit notifies the plurality of base station devices of information regarding a maximum number of layers for each of the plurality of MIMO schemes as the available information. The terminal device according to claim 1 .

3. The notification unit notifies the plurality of base station devices of information indicating the plurality of MIMO schemes as the available information. The terminal device according to claim 1 .

4. The notification unit notifies the plurality of base station devices of type information indicating that the terminal device is a terminal device of a specific type capable of using the plurality of MIMO schemes as the usability information. The terminal device according to claim 1 .

5. The available information notified by the notification unit is The terminal device may further include a plurality of base station devices that are located at different positions. The terminal device according to claim 1 .

6. A wireless communication method executed by a terminal device capable of wireless communication with a plurality of base station devices, comprising: receiving an inquiry regarding capability information of the terminal device from one base station device among the plurality of base station devices; When the terminal device is capable of communicating with the plurality of base station devices disposed at different positions, notifying the one base station device of usable information indicating that the terminal device is capable of using a plurality of MIMO schemes having different maximum numbers of layers usable therein, as the capability information, based on the inquiry; receiving a radio signal transmitted by the one base station device using a MIMO scheme set based on the capability information; A wireless communication method comprising: