JP7753521B2 - Terminal, base station and communication method - Google Patents

Description

The present invention relates to a terminal, a base station, and a communication method in a wireless communication system.

For NR (New Radio) (also known as "5G"), the successor system to LTE (Long Term Evolution), technologies are being considered that meet the requirements of a large-capacity system, high data transmission speeds, low latency, simultaneous connection of a large number of terminals, low cost, and low power consumption (for example, non-patent document 1).

Furthermore, studies have begun on 6G as the next-generation wireless communication system after 5G, and it is expected to achieve wireless quality that exceeds that of 5G. For example, studies are underway for 6G to achieve even greater capacity, the use of new frequency bands, even lower latency, even higher reliability, even lower power consumption, and the expansion of coverage into new areas (high altitude, sea, and space) using non-terrestrial networks.

3GPP TS 38.300 V16.8.0 (2021-12)

Studies are being conducted to enhance uplink transmission in multi-carrier systems. For example, studies are being conducted to enable a terminal that supports up to two simultaneous transmissions to dynamically switch the band for transmitting the uplink across three or four bands. Here, when considering TAGs (Timing Advance Groups), it is expected that switching the band for transmitting the uplink will be restricted.

The present invention has been made in consideration of the above points and aims to suitably switch the band for transmitting the uplink in a wireless communication system.

According to the disclosed technology, in a transmission switching method in which at least one of multiple antenna ports can switch bands, a terminal is provided that includes a receiver that receives a band switching instruction via downlink, and a control unit that, when switching to a band that belongs to a group with a different uplink timing advance, performs random access on another band that belongs to the same group as the band to which the switch is made.

The disclosed technology provides a technology that enables a wireless communication system to suitably switch the band for transmitting the uplink.

1 is a diagram illustrating a wireless communication system according to an embodiment of the present invention. FIG. 1 is a diagram illustrating power allocation in conventional downlink transmission. FIG. 1 is a diagram for explaining Example 1 of an embodiment of the present invention. FIG. 10 is a diagram for explaining Example 2 of an embodiment of the present invention. FIG. 10 is a diagram for explaining Example 3 of an embodiment of the present invention. FIG. 10 is a diagram for explaining Example 4 of an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a functional configuration of a base station according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a hardware configuration of a base station or a terminal according to an embodiment of the present invention. 1 is a diagram showing an example of a configuration of a vehicle according to an embodiment of the present invention;

The following describes an embodiment of the present invention with reference to the drawings. Note that the embodiment described below is an example, and the embodiments to which the present invention can be applied are not limited to the following embodiment.

Existing technologies are used as appropriate when operating the wireless communication system of an embodiment of the present invention. However, the existing technologies in question may be, for example, existing LTE, but are not limited to existing LTE. Furthermore, the term "LTE" used in this specification has a broad meaning that includes LTE-Advanced and systems subsequent to LTE-Advanced (e.g., NR), unless otherwise specified.

In addition, in the embodiments of the present invention described below, terms used in existing LTE, such as SS (Synchronization signal), PSS (Primary SS), SSS (Secondary SS), PBCH (Physical broadcast channel), PRACH (Physical random access channel), PDCCH (Physical Downlink Control Channel), PDSCH (Physical Downlink Shared Channel), PUCCH (Physical Uplink Control Channel), and PUSCH (Physical Uplink Shared Channel), are used. This is for convenience of description, and similar signals, functions, etc. may be referred to by other names. Furthermore, the above-mentioned terms in NR correspond to NR-SS, NR-PSS, NR-SSS, NR-PBCH, NR-PRACH, etc. However, even signals used in NR are not necessarily referred to as "NR-".

Furthermore, in an embodiment of the present invention, the duplex method may be a TDD (Time Division Duplex) method, an FDD (Frequency Division Duplex) method, or another method (e.g., Flexible Duplex, etc.).

Furthermore, in an embodiment of the present invention, "configuring" radio parameters, etc. may mean that predetermined values are pre-configured, or that radio parameters notified from the base station 10 or terminal 20 are set.

(System configuration)
FIG. 1 is a diagram illustrating a wireless communication system according to an embodiment of the present invention.
As shown in Fig. 1, a wireless communication system according to an embodiment of the present invention includes a base station 10 and a terminal 20. Although Fig. 1 shows one base station 10 and one terminal 20, this is an example, and there may be a plurality of each.

A base station 10 is a communication device that provides one or more cells and performs wireless communication with terminals 20. The physical resources of a wireless signal are defined in the time domain and the frequency domain, where the time domain may be defined by the number of Orthogonal Frequency Division Multiplexing (OFDM) symbols, and the frequency domain may be defined by the number of subcarriers or resource blocks. Furthermore, a TTI (Transmission Time Interval) in the time domain may be a slot, or a TTI may be a subframe.

The base station 10 transmits synchronization signals and system information to the terminal 20. The synchronization signals are, for example, NR-PSS and NR-SSS. The system information is transmitted, for example, via NR-PBCH and is also referred to as broadcast information. The synchronization signals and system information may also be referred to as SSB (SS/PBCH block). As shown in FIG. 1, the base station 10 transmits control signals or data to the terminal 20 via DL (Downlink) and receives control signals or data from the terminal 20 via UL (Uplink). Both the base station 10 and the terminal 20 are capable of transmitting and receiving signals using beamforming. Furthermore, both the base station 10 and the terminal 20 are capable of applying MIMO (Multiple Input Multiple Output) communication to the DL or UL. Furthermore, both the base station 10 and the terminal 20 may communicate via a secondary cell (SCell: Secondary Cell) and a primary cell (PCell: Primary Cell) using CA (Carrier Aggregation). Furthermore, the terminal 20 may perform communication via a primary cell of the base station 10 and a primary secondary cell group cell (PSCell: Primary SCG Cell) of another base station 10 using DC (Dual Connectivity).

The terminal 20 is a communication device equipped with wireless communication functions, such as a smartphone, mobile phone, tablet, wearable device, or M2M (Machine-to-Machine) communication module. As shown in FIG. 1, the terminal 20 receives control signals or data from the base station 10 via DL and transmits control signals or data to the base station 10 via UL, thereby utilizing various communication services provided by the wireless communication system. The terminal 20 also receives various reference signals transmitted from the base station 10 and measures propagation path quality based on the reception results of the reference signals. The terminal 20 may also be referred to as a UE, and the base station 10 as a gNB.

Next, we will discuss the status of discussions on base station power saving in NR Release 18. Base station and terminal techniques for improving network energy saving from both the base station's transmission and reception perspectives are being considered. For example, methods are being considered for a base station to more efficiently achieve dynamic and/or semi-static finer-granularity adaptation of transmission and/or reception using network energy saving techniques in one or more of the time, frequency, space, and power domains using potential support/feedback from terminals and potential assistance information.

(Band switching in conventional uplink transmission)
Next, band switching in conventional uplink transmission will be described.

Figure 2 is a diagram explaining band switching in conventional uplink transmission. Studies are being conducted to enhance uplink transmission in multi-carrier. As shown in Figure 3, studies are being conducted on the operation of a terminal that supports up to two simultaneous transmissions in FR1 (Frequency Range 1) to dynamically switch the band for uplink transmission across three or four bands. In the example of Figure 3, each of the two ports can switch between using Band A, Band B, Band C, and Band D.

In addition, band switching operations for dynamic uplink transmissions between bands in single TAG (Timing Advance Group) and multiple TAG environments are also being considered. For example, when communicating with non-collocated cells, it is expected that different TAGs will be configured for each cell. A TAG is a group of bands with the same uplink timing advance.

However, conventionally, there has been a problem in that the instructions for band switching operations in uplink transmissions are not clear when different TAGs are set for each cell.

Furthermore, when considering band switching operations in uplink transmission, there is a possibility that switching will occur for uplink carriers that do not have a paired downlink carrier. For example, if two downlink carriers are configured and four uplink carriers that can be switched by band switching operations in uplink transmission are configured, it is possible that two of the uplink carriers will not have a paired downlink carrier.

(Outline of this embodiment)
In this embodiment, an example will be described in which a band switching operation instruction in uplink transmission is clarified when different TAGs are set for each cell. Hereinafter, examples 1 to 5 will be described as examples of implementing this embodiment.

Example 1
In this embodiment, an example will be described in which the terminal 20 performs band switching in uplink transmission when performing random access based on an instruction from the base station 10.

The terminal 20 may assume that a switching delay is specified when performing band switching in uplink transmission in order to perform random access.

The terminal 20 may notify the base station 10 of its terminal capability regarding band switching in uplink transmission for performing random access. For example, the terminal 20 may notify the base station 10 of its terminal capability indicating whether it supports band switching in uplink transmission for performing random access, or may notify the base station 10 of its terminal capability indicating whether it supports a switching delay regarding band switching in uplink transmission for performing random access or the length of the switching delay.

When random access is performed based on instructions from base station 10, any of the following options may be used.

<Plan 1-1>
The terminal 20 may determine whether or not it is necessary to perform random access based on the uplink band scheduled by the base station 10. For example, when it is necessary to perform band switching in uplink transmission across TAGs due to uplink scheduling from the base station 10 or the like, the terminal 20 may perform random access in the TAG to which the band is to be switched.

<Plan 1-2>
The terminal 20 may assume that it receives an explicit instruction to perform random access from the base station 10. For example, the terminal 20 may assume that it receives an explicit instruction from the base station 10 to perform random access in the TAG before the base station 10 performs uplink scheduling or the like.

Figure 3 is a diagram for explaining Example 1 of an embodiment of the present invention. Figure 3 shows an example in which port 1 is switched to band C, which belongs to TAG 2 and is not in use.

In the case of Proposal 1-1, in the case shown in Figure 3, terminal 20 needs to switch to band C, which spans TAGs, due to the scheduling of uplink transmission in band C, so it performs random access in TAG2, the destination of the switch.

Also, in the case of Proposal 1-2, in the case shown in Figure 3, terminal 20 is instructed to perform random access in band C and performs random access in TAG2, which is the switching destination.

The terminal 20 may perform band switching in uplink transmission and assume that for bands/carriers where switching delays (switching periods, etc.) occur when performing random access (PRACH transmission), switching delays (switching periods, etc.) will always occur in bands/carriers different from the bands/carriers where PRACH transmission is performed.

In other words, the terminal 20 may assume that no switching delay (switching period, etc.) occurs on the band/carrier on which PRACH transmission is performed.

In addition, the terminal 20 may assume that for bands/carriers in which switching delays (switching periods, etc.) occur, switching delays (switching periods, etc.) will always occur in the bands/carriers in which PRACH transmission is performed.

Furthermore, unlike in the case of other channels (such as PUSCH), the terminal 20 may assume that the setting indicating which band/carrier the switching delay (switching period, etc.) will occur in is not set in the case of the band/carrier on which PRACH transmission is performed.

Example 2
In this embodiment, an example will be described in which, after the random access procedure in the first embodiment is completed, the combination of bands is restored to the original combination before switching.

Figure 4 is a diagram illustrating Example 2 of an embodiment of the present invention. After the random access procedure is completed, terminal 20 may switch back to the original band combination from which it was switched. For example, as shown in Figure 3, terminal 20 may switch the band of port 1 from band A to band C based on an instruction to perform random access in band C, and then, after the random access procedure is completed, switch the band of port 1 from band C back to band A.

In addition, after switching the band of port 1 from band A to band C based on an instruction to perform random access in band C, terminal 20 may switch the band of port 1 back from band C to band A after a specified period has elapsed and the random access procedure has ended. Terminal 20 may assume that this period is specified in the specifications, or that it is set in RRC or specified in MAC-CE, DCI, etc. Furthermore, this period may or may not include the time required for the switchback.

Example 3
In this embodiment, an example will be described in which synchronization of uplink transmission is performed and maintained in a TAG that may become a switching destination.

The terminal 20 may perform and maintain synchronization of uplink transmissions from the TAG it is maintaining to a TAG to which it may switch bands for uplink transmissions.

The terminal 20 may perform and maintain synchronization of uplink transmissions by performing random access, etc., when a TAG that may be a potential destination for switching from the TAG that is being maintained is set.

Figure 5 is a diagram for explaining Example 3 of an embodiment of the present invention. In the example shown in Figure 5, the only combination of transmission bands before switching is TAG1, but since there is a possibility of switching to TAG2, uplink transmission synchronization may also be performed and maintained (i.e., random access may be performed) in TAG2.

Example 4
In this embodiment, an example will be described in which random access is performed on another uplink carrier that belongs to the same TAG as the uplink carrier to which switching is to be performed.

The terminal 20 may determine the carrier on which to perform random access depending on whether the target uplink carrier has a paired downlink carrier. For example, when the terminal 20 needs to perform uplink transmission synchronization on an uplink carrier that does not have a paired downlink carrier, the terminal 20 may perform random access on another uplink carrier that belongs to the same TAG as the uplink carrier.

The terminal 20 may assume that it is notified or specified which carrier of the same TAG will be used to perform random access. Furthermore, the terminal 20 may assume that other carriers of the same TAG on which random access will be performed are limited to uplink carriers that have a paired downlink carrier. The terminal 20 may assume that it is not possible to set up a RACH, etc., for an uplink carrier that does not have a paired downlink carrier.

Figure 6 is a diagram for explaining Example 4 of an embodiment of the present invention. For example, as shown in Figure 6, when an instruction to switch port 1 from band A to band D is notified (and uplink transmission of TAG2 is not synchronized), terminal 20 may perform random access in band C.

In this case, terminal 20 may first switch port 1 from band A to band C to perform random access, and then switch port 1 from band C to band D after the random access procedure is completed.

Example 5
In this embodiment, an example is described in which uplink communication of a random access procedure is performed on the uplink carrier to which the switch is made, and downlink communication of a random access procedure is performed on a downlink carrier corresponding to another uplink carrier that belongs to the same TAG as the uplink carrier to which the switch is made.

Terminal 20 may determine the carriers to be used for uplink communication and downlink communication in the random access procedure depending on whether the target uplink carrier has a paired downlink carrier. For example, when terminal 20 switches to an uplink carrier that does not have a paired downlink carrier, it may transmit uplink signals related to random access on that uplink carrier, and receive and synchronize downlink signals (SSB, SIB, etc.) related to random access, downlink channels (PDCCH, PDSCH, etc.), etc., using signals/information on a downlink carrier paired with another uplink carrier belonging to the same TAG to perform random access.

The terminal 20 may assume that it is notified or specified which carrier of the same TAG will be used to perform downlink operations related to random access. Furthermore, the terminal 20 may assume that RACH configuration, etc. will be performed on an uplink carrier that does not have a paired downlink carrier.

For example, as shown in Figure 6, if an instruction is notified to switch port 1 from band A to band D as in the example shown on the previous page (and the uplink transmission of TAG2 is not synchronized), uplink operations related to random access may be performed on band D, and downlink operations related to random access may be performed on band C.

The terms band and carrier in this embodiment may be interpreted interchangeably. This embodiment may also be applied to any of SUL (Supplementary Uplink), non-SUL, and SUL/non-SUL combinations.

In this embodiment, an example of two-port transmission (uplink transmission of a total of two bands) is described, but the scope of application of this embodiment is not limited to this, and may be, for example, one-port transmission (uplink transmission of a total of one band), three-port transmission (uplink transmission of a total of three bands), four-port transmission (uplink transmission of a total of four bands), or more port transmission (uplink transmission of a total of five or more bands).

In this embodiment, the case of two TAG1s and two TAG2s has been mainly exemplified, but this embodiment can also be applied to other patterns, such as TAG1:TAG2 = 1:3, TAG1:TAG2 = 3:1, TAG1:TAG2:TAG3 = 1:1:2, etc.

This embodiment can be applied not only to the ratio of the number of UL carriers (with DL carriers) to the number of UL carriers (without DL carriers) illustrated in the figures above, but also to other patterns (for example, in the case of four carriers, 2:2, 1:3, 3:1, etc.).

(Device configuration)
Next, an example of the functional configuration of the base station 10 and the terminal 20 that execute the processes and operations described above will be described.

<Base station 10>
FIG. 7 is a diagram showing an example of the functional configuration of the base station 10. As shown in FIG. 7, the base station 10 has a transmitting unit 110, a receiving unit 120, a setting unit 130, and a control unit 140. The functional configuration shown in FIG. 7 is merely an example. The names of the functional divisions and functional units may be any as long as they can perform the operations related to the embodiment of the present invention. Furthermore, the transmitting unit 110 and the receiving unit 120 may be collectively referred to as a communication unit.

The transmitter 110 has the function of generating signals to be transmitted to the terminal 20 and transmitting these signals wirelessly. The receiver 120 has the function of receiving various signals transmitted from the terminal 20 and obtaining, for example, information of higher layers from the received signals. The transmitter 110 also has the function of transmitting NR-PSS, NR-SSS, NR-PBCH, DL/UL control signals, DCI via PDCCH, data via PDSCH, etc. to the terminal 20.

The setting unit 130 stores pre-set setting information and various setting information to be transmitted to the terminal 20 in a storage device provided in the setting unit 130, and reads it from the storage device as needed.

The control unit 140 schedules DL reception or UL transmission of the terminal 20 via the transmission unit 110. The control unit 140 also includes a function for performing LBT. The functional unit related to signal transmission in the control unit 140 may be included in the transmission unit 110, and the functional unit related to signal reception in the control unit 140 may be included in the reception unit 120. The transmission unit 110 may also be called a transmitter, and the reception unit 120 may also be called a receiver.

<Terminal 20>
Fig. 8 is a diagram showing an example of the functional configuration of the terminal 20. As shown in Fig. 8, the terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in Fig. 8 is merely an example. As long as the operations related to the embodiment of the present invention can be performed, the names of the functional divisions and functional units may be any. The transmitting unit 210 and the receiving unit 220 may be collectively referred to as a communication unit.

The transmitter 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The receiver 220 receives various signals wirelessly and obtains higher layer signals from the received physical layer signals. The receiver 220 also has the function of receiving NR-PSS, NR-SSS, NR-PBCH, DL/UL/SL control signals, DCI via PDCCH, data via PDSCH, etc. transmitted from the base station 10. Furthermore, for example, the transmitting unit 210 may transmit a PSCCH (Physical Sidelink Control Channel), a PSSCH (Physical Sidelink Shared Channel), a PSDCH (Physical Sidelink Discovery Channel), a PSBCH (Physical Sidelink Broadcast Channel), or the like to another terminal 20 as D2D communication, and the receiving unit 120 may receive the PSCCH, the PSSCH, the PSDCH, the PSBCH, or the like from the other terminal 20.

The setting unit 230 stores various setting information received by the receiving unit 220 from the base station 10 or other terminals in a storage device provided in the setting unit 230, and reads it from the storage device as needed. The setting unit 230 also stores setting information that is set in advance. The control unit 240 controls the terminal 20. The control unit 240 also includes a function to perform LBT.

The terminal of this embodiment may be configured as the terminal shown in each of the following items. The following communication methods may also be implemented.

<Configuration of this embodiment>
(Section 1)
In a transmission switching method in which at least one antenna port among a plurality of antenna ports can switch bands, a receiver that receives an instruction to switch bands via downlink;
a control unit that, when switching to a band belonging to a group having a different uplink timing advance, executes random access in another band belonging to the same group as the band to which the uplink timing advance is switched;
Terminal.
(Section 2)
The control unit performs uplink communication in the random access procedure in the band to which the switching is made, and performs downlink communication in the random access procedure in the other band.
2. The terminal according to claim 1.
(Section 3)
the control unit, when a downlink band to be paired with the switching destination band is not set, performs random access in the other band.
3. The terminal according to claim 1 or 2.
(Section 4)
In a transmission switching method in which at least one antenna port among a plurality of antenna ports can switch bands, a transmitter that transmits a band switching instruction to a terminal;
A control unit that assumes that when switching to a band belonging to a group with a different uplink timing advance, random access is performed by the terminal in another band belonging to the same group as the band to which the switching is made.
Base station.
(Section 5)
In a transmission switching scheme in which at least one antenna port among a plurality of antenna ports can switch bands, the method includes: receiving an indication of a band switch via a downlink;
When switching to a band belonging to a group having a different uplink timing advance, performing random access in another band belonging to the same group as the band to which the switching is made.
The communication method implemented by the device.

Any of the above configurations provides technology that enables a wireless communication system to suitably switch the band for transmitting the uplink. According to paragraph 1, random access can be performed in another band that belongs to the same group as the band to which the switch is made. According to paragraph 2, uplink communication in the random access procedure can be performed in the band to which the switch is made, and downlink communication in the random access procedure can be performed in another band. According to paragraph 3, if the band to which the switch is made does not have a paired downlink band set, random access can be performed in the other band.

(Hardware configuration)
The block diagrams (FIGS. 7 and 8) used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are directly or indirectly connected (e.g., wired, wireless, etc.) and these multiple devices. The functional block may also be realized by combining software with the single device or multiple devices.

Functions include, but are not limited to, judgment, determination, assessment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, election, establishment, comparison, assumption, expectation, regard, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs transmission functions is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on how these functions are implemented.

For example, the base station 10, terminal 20, etc. in one embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. Figure 9 is a diagram showing an example of the hardware configuration of the base station 10 and terminal 20 in one embodiment of the present disclosure. The above-mentioned base station 10 and terminal 20 may be physically configured as a computer device including a processor 1001, a memory device 1002, an auxiliary memory device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

In the following description, the term "apparatus" can be interpreted as a circuit, device, unit, etc. The hardware configuration of the base station 10 and terminal 20 may be configured to include one or more of the devices shown in the figure, or may be configured to exclude some of the devices.

Each function in the base station 10 and the terminal 20 is realized by loading specified software (programs) onto hardware such as the processor 1001 and the memory device 1002, causing the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of reading and writing data in the memory device 1002 and the auxiliary memory device 1003.

The processor 1001, for example, runs an operating system to control the entire computer. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control unit, an arithmetic unit, registers, etc. For example, the above-mentioned control unit 140, control unit 240, etc. may be realized by the processor 1001.

The processor 1001 also reads programs (program code), software modules, data, etc. from at least one of the auxiliary storage device 1003 and the communication device 1004 into the storage device 1002, and executes various processes in accordance with these. The program used is a program that causes a computer to execute at least some of the operations described in the above-mentioned embodiments. For example, the control unit 140 of the base station 10 shown in FIG. 7 may be implemented by a control program stored in the storage device 1002 and running on the processor 1001. For example, the control unit 240 of the terminal 20 shown in FIG. 8 may be implemented by a control program stored in the storage device 1002 and running on the processor 1001. While the various processes described above have been described as being executed by one processor 1001, they may also be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The program may also be transmitted from a network via a telecommunications line.

The storage device 1002 is a computer-readable recording medium and may be composed of, for example, at least one of ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), etc. The storage device 1002 may also be called a register, cache, main memory, etc. The storage device 1002 can store executable programs (program code), software modules, etc. for implementing a communication method according to one embodiment of the present disclosure.

The auxiliary storage device 1003 is a computer-readable recording medium, and may be composed of, for example, at least one of an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray (registered trademark) disk), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy (registered trademark) disk, a magnetic strip, etc. The above-mentioned storage medium may be, for example, a database, a server, or other suitable medium that includes at least one of the storage device 1002 and the auxiliary storage device 1003.

The communication device 1004 is hardware (transmitting/receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, network controller, network card, or communication module. The communication device 1004 may be configured to include a high-frequency switch, duplexer, filter, frequency synthesizer, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the transmitting/receiving antenna, amplifier, transmitting/receiving unit, transmission path interface, etc. may be realized by the communication device 1004. The transmitting/receiving unit may be implemented as a physically or logically separated transmitting unit and receiving unit.

The input device 1005 is an input device (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.) that accepts input from the outside. The output device 1006 is an output device (e.g., a display, speaker, LED lamp, etc.) that outputs to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one structure (e.g., a touch panel).

Furthermore, each device, such as the processor 1001 and the storage device 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

Furthermore, the base station 10 and the terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized by such hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

Figure 10 shows an example configuration of vehicle 2001. As shown in Figure 10, vehicle 2001 comprises a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, front wheels 2007, rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013. Each aspect/embodiment described in this disclosure may be applied to a communication device installed in vehicle 2001, for example, to communication module 2013.

The drive unit 2002 is composed of, for example, an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and rear wheels based on the operation of the steering wheel operated by the user.

The electronic control unit 2010 is composed of a microprocessor 2031, memory (ROM, RAM) 2032, and a communication port (IO port) 2033. Signals are input to the electronic control unit 2010 from various sensors 2021 to 2029 provided in the vehicle 2001. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

Signals from the various sensors 2021 to 2029 include a current signal from a current sensor 2021 that senses the motor current, a front and rear wheel rotation speed signal obtained by a rotation speed sensor 2022, a front and rear wheel air pressure signal obtained by an air pressure sensor 2023, a vehicle speed signal obtained by a vehicle speed sensor 2024, an acceleration signal obtained by an acceleration sensor 2025, an accelerator pedal depression amount signal obtained by an accelerator pedal sensor 2029, a brake pedal depression amount signal obtained by a brake pedal sensor 2026, a shift lever operation signal obtained by a shift lever sensor 2027, and a detection signal for detecting obstacles, vehicles, pedestrians, etc. obtained by an object detection sensor 2028.

The information service unit 2012 is composed of various devices, such as a car navigation system, audio system, speakers, television, and radio, for providing (outputting) various information such as driving information, traffic information, and entertainment information, as well as one or more ECUs that control these devices. The information service unit 2012 uses information obtained from external devices via the communication module 2013, etc., to provide various multimedia information and multimedia services to the occupants of the vehicle 2001.

The information service unit 2012 may include input devices (e.g., keyboards, mice, microphones, switches, buttons, sensors, touch panels, etc.) that accept input from the outside, and may also include output devices (e.g., displays, speakers, LED lamps, touch panels, etc.) that output to the outside.

The driving assistance system unit 2030 is composed of various devices that provide functions to prevent accidents and reduce the driver's driving burden, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS, etc.), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps, etc.), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System), etc.), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. The driving assistance system unit 2030 also transmits and receives various information via the communication module 2013 to realize driving assistance functions or autonomous driving functions.

The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 between the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021-29, all of which are provided on the vehicle 2001.

The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with an external device. For example, it transmits and receives various information to and from the external device via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station, a mobile station, etc.

The communication module 2013 may transmit at least one of the signals from the various sensors 2021-2029 described above input to the electronic control unit 2010, information obtained based on the signals, and information based on input from the outside (user) obtained via the information service unit 2012 to an external device via wireless communication. The electronic control unit 2010, the various sensors 2021-2029, the information service unit 2012, etc. may be referred to as input units that accept input. For example, the PUSH transmitted by the communication module 2013 may include information based on the above input.

The communication module 2013 receives various information (traffic information, traffic signal information, vehicle distance information, etc.) transmitted from external devices and displays it on the information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may also be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker based on the PDSCH (or data/information decoded from the PDSCH) received by the communication module 2013).

In addition, the communication module 2013 stores various information received from external devices in memory 2032 that can be used by the microprocessor 2031. Based on the information stored in memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axles 2009, sensors 2021 to 2029, etc., provided on the vehicle 2001.

(Supplementary explanation of the embodiment)
Although the embodiments of the present invention have been described above, the disclosed invention is not limited to such embodiments, and those skilled in the art will understand various modifications, alterations, alternatives, and substitutions. While specific numerical examples have been used to facilitate understanding of the invention, unless otherwise specified, these numerical values are merely examples, and any appropriate values may be used. The division of items in the above description is not essential to the present invention; matters described in two or more items may be used in combination as needed, and matters described in one item may apply to matters described in another item (unless inconsistent). Boundaries between functional units or processing units in functional block diagrams do not necessarily correspond to boundaries between physical components. The operations of multiple functional units may be performed by a single physical component, or the operations of a single functional unit may be performed by multiple physical components. The order of processing steps described in the embodiments may be reversed as long as there is no contradiction. For convenience of processing description, the base station 10 and terminal 20 have been described using functional block diagrams, but such devices may be implemented in hardware, software, or a combination thereof. The software operated by the processor of the base station 10 in accordance with an embodiment of the present invention and the software operated by the processor of the terminal 20 in accordance with an embodiment of the present invention may each be stored in random access memory (RAM), flash memory, read-only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server, or any other suitable storage medium.

Furthermore, the notification of information is not limited to the aspects/embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling), broadcast information (Master Information Block (MIB), System Information Block (SIB)), other signals, or a combination thereof. Furthermore, RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, etc.

The aspects/embodiments described in this disclosure may be based on LTE (Long Term Evolution), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (xG (x is, for example, an integer or decimal number)), FRA (Future Radio Access), NR (new Radio), New radio access (NX), Future generation radio access (FX), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE The present invention may be applied to at least one of systems using 802.20, UWB (Ultra-Wide Band), Bluetooth (registered trademark), or other suitable systems, and next-generation systems that are extended, modified, created, or defined based on these systems. The present invention may also be applied to a combination of multiple systems (e.g., a combination of LTE and/or LTE-A with 5G).

The order of the procedures, sequences, flowcharts, etc. of each aspect/embodiment described herein may be rearranged unless inconsistent. For example, the methods described in this disclosure present elements of various steps using an example order and are not limited to the particular order presented.

Specific operations described herein as being performed by the base station 10 may also be performed by its upper node in some cases. In a network consisting of one or more network nodes including a base station 10, it is clear that various operations performed for communication with a terminal 20 may be performed by at least one of the base station 10 and other network nodes other than the base station 10 (such as, but not limited to, an MME or S-GW). While the above example illustrates a case where there is one other network node other than the base station 10, the other network node may also be a combination of multiple other network nodes (for example, an MME and an S-GW).

The information or signals described in this disclosure may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer). They may also be input and output via multiple network nodes.

Input and output information may be stored in a specific location (e.g., memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be sent to another device.

In this disclosure, the determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a numerical comparison (e.g., comparison with a predetermined value).

Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Software, instructions, information, etc. may also be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and/or wireless technologies (such as infrared, microwave), these wired and/or wireless technologies are included within the definition of transmission media.

The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

Note that terms explained in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

As used in this disclosure, the terms "system" and "network" are used interchangeably.

Furthermore, the information, parameters, etc. described in this disclosure may be expressed using absolute values, relative values from a predetermined value, or other corresponding information. For example, radio resources may be indicated by an index.

The names used for the above-described parameters are not intended to be limiting in any way. Furthermore, the mathematical formulas, etc. using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not intended to be limiting in any way.

In this disclosure, terms such as "base station (BS)," "radio base station," "base station," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," "access point," "transmission point," "reception point," "transmission/reception point," "cell," "sector," "cell group," "carrier," and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

A base station can accommodate one or more (e.g., three) cells. When a base station accommodates multiple cells, the entire coverage area of the base station can be divided into multiple smaller areas, and each smaller area can also be provided with communication services by a base station subsystem (e.g., a small indoor base station (RRH: Remote Radio Head)). The terms "cell" or "sector" refer to part or all of the coverage area of a base station and/or base station subsystem that provides communication services within this coverage area.

In this disclosure, a base station sending information to a terminal may be interpreted as the base station instructing the terminal to control or operate based on the information.

In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable terminology.

At least one of the base station and the mobile station may be referred to as a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may be a device mounted on a mobile body, or the mobile body itself. The mobile body may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may also include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

Furthermore, the base station in the present disclosure may be read as a user terminal. For example, each aspect/embodiment of the present disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple terminals 20 (which may be referred to as, for example, D2D (Device-to-Device) or V2X (Vehicle-to-Everything)). In this case, the terminal 20 may be configured to have the functions possessed by the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to communication between terminals (for example, "side"). For example, terms such as uplink channel and downlink channel may be read as side channel.

Similarly, the user terminal in this disclosure may be interpreted as a base station. In this case, the base station may be configured to have the functions possessed by the user terminal described above.

As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching a table, database, or other data structure), and ascertaining something that is considered a "determination." Also, "determining" and "determining" may include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and other actions that are considered a "determination." Furthermore, "judgment" and "decision" can include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judged" or "decided." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

The terms "connected," "coupled," or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using one or more wires, cables, and/or printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

The reference signal may also be abbreviated as RS (Reference Signal) or may be called a pilot depending on the applicable standard.

As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must in some way precede the second element.

The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Furthermore, when the term "or" is used in this disclosure, it is not intended to be an exclusive or.

A radio frame may be composed of one or more frames in the time domain. Each of the one or more frames in the time domain may be called a subframe. A subframe may further be composed of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

Numerology may be a communication parameter that applies to at least one of the transmission and reception of a signal or channel. Numerology may indicate, for example, at least one of the following: subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame structure, specific filtering operations performed by the transceiver in the frequency domain, and specific windowing operations performed by the transceiver in the time domain.

A slot may consist of one or more symbols in the time domain (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol or a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol). A slot may also be a time unit based on numerology.

A slot may include multiple minislots. Each minislot may consist of one or more symbols in the time domain. A minislot may also be called a subslot. A minislot may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called PDSCH (or PUSCH) mapping type B.

Radio frame, subframe, slot, minislot, and symbol all represent time units for transmitting signals. Other names may also be used for radio frame, subframe, slot, minislot, and symbol.

For example, one subframe may be called a transmission time interval (TTI), multiple consecutive subframes may be called a TTI, or one slot or one minislot may be called a TTI. In other words, at least one of the subframe and the TTI may be a subframe (1 ms) in existing LTE, a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc. instead of a subframe.

Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station schedules each terminal 20 by allocating radio resources (such as frequency bandwidth and transmission power that can be used by each terminal 20) in TTI units. Note that the definition of TTI is not limited to this.

A TTI may be a transmission time unit for a channel-coded data packet (transport block), code block, code word, etc., or may be a processing unit for scheduling, link adaptation, etc. Note that when a TTI is given, the time interval (e.g., the number of symbols) to which a transport block, code block, code word, etc. is actually mapped may be shorter than the TTI.

Note that when one slot or one minislot is referred to as a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the smallest time unit for scheduling. Furthermore, the number of slots (minislots) that constitute the smallest time unit for scheduling may be controlled.

A TTI with a time length of 1 ms may be referred to as a regular TTI (TTI in LTE Rel. 8-12), normal TTI, long TTI, regular subframe, normal subframe, long subframe, slot, etc. A TTI shorter than a regular TTI may be referred to as a shortened TTI, short TTI, partial TTI (partial or fractional TTI), shortened subframe, short subframe, minislot, subslot, slot, etc.

Note that a long TTI (e.g., a normal TTI, a subframe, etc.) may be interpreted as a TTI having a time length of more than 1 ms, and a short TTI (e.g., a shortened TTI, etc.) may be interpreted as a TTI having a TTI length shorter than that of a long TTI and greater than or equal to 1 ms.

A resource block (RB) is a resource allocation unit in the time and frequency domains, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of numerology, for example, 12. The number of subcarriers included in an RB may also be determined based on numerology.

Furthermore, the time domain of an RB may include one or more symbols and may be one slot, one minislot, one subframe, or one TTI in length. One TTI, one subframe, etc. may each consist of one or more resource blocks.

In addition, one or more RBs may also be referred to as a physical resource block (PRB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, etc.

A resource block may also be composed of one or more resource elements (REs). For example, one RE may be a radio resource region of one subcarrier and one symbol.

A Bandwidth Part (BWP) (which may also be referred to as a partial bandwidth) may represent a subset of contiguous common resource blocks (RBs) for a given numerology on a given carrier, where the common RBs may be identified by their index relative to a Common Reference Point of the carrier. PRBs may be defined in a BWP and numbered within that BWP.

BWPs may include a BWP for UL (UL BWP) and a BWP for DL (DL BWP). One or more BWPs may be configured within one carrier for a terminal 20.

At least one of the configured BWPs may be active, and the terminal 20 may not expect to transmit or receive a specific signal/channel outside the active BWP. Note that the terms "cell," "carrier," etc. in this disclosure may be read as "BWP."

The above-described structures of radio frames, subframes, slots, minislots, and symbols are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, as well as the number of symbols in a TTI, symbol length, and cyclic prefix (CP) length can be varied in various ways.

In this disclosure, where articles are added by translation, such as a, an, and the in English, this disclosure may include the noun following these articles being plural.

In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combined" may also be interpreted in the same way as "different."

Each aspect/embodiment described in this disclosure may be used alone, in combination, or switched between depending on the implementation. Furthermore, notification of specified information (e.g., notification that "X is true") is not limited to being done explicitly, but may also be done implicitly (e.g., not notifying the specified information).

Although the present disclosure has been described in detail above, it will be clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure.

10 Base station 110 Transmitter 120 Receiver 130 Setting unit 140 Control unit 20 Terminal 210 Transmitter 220 Receiver 230 Setting unit 240 Control unit 1001 Processor 1002 Storage device 1003 Auxiliary storage device 1004 Communication device 1005 Input device 1006 Output device 2001 Vehicle 2002 Drive unit 2003 Steering unit 2004 Accelerator pedal 2005 Brake pedal 2006 Shift lever 2007 Front wheels 2008 Rear wheels 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 Rotation speed sensor 2023 Air pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030: Driving assistance system unit 2031: Microprocessor 2032: Memory (ROM, RAM)
2033 Communication port (IO port)

Claims (5)

In a transmission switching method in which at least one antenna port among a plurality of antenna ports can switch bands, a receiver that receives an instruction to switch bands via downlink;
a control unit that, when switching to a band belonging to a group having a different uplink timing advance, executes random access in another band belonging to the same group as the band to which the uplink timing advance is switched;
Terminal. The control unit performs uplink communication in the random access procedure in the band to which the switching is made, and performs downlink communication in the random access procedure in the other band.
The terminal according to claim 1 . the control unit, when a downlink band to be paired with the switching destination band is not set, performs random access in the other band.
The terminal according to claim 1 . In a transmission switching method in which at least one antenna port among a plurality of antenna ports can switch bands, a transmitter that transmits a band switching instruction to a terminal;
A control unit that assumes that when switching to a band belonging to a group with a different uplink timing advance, random access is performed by the terminal in another band belonging to the same group as the band to which the switching is made.
Base station. In a transmission switching scheme in which at least one antenna port among a plurality of antenna ports can switch bands, receiving an indication of band switching via a downlink;
When switching to a band belonging to a group having a different uplink timing advance, performing random access in another band belonging to the same group as the band to which the switching is made.
The communication method implemented by the device.