Terminal device, base station device, and wireless communication system

Abstract

This terminal device transmits a PRACH to a base station device. The terminal device comprises: a reception unit that receives first information pertaining to a first RO that can be used by each of the terminal device and other terminal devices, and second information pertaining to a second RO that can be used by the terminal device and that is not available to the other terminal devices; a control unit that, in accordance with the second information or the first information and the second information, identifies the RO allocated to the terminal device from the first RO and the second RO; and a transmission unit that transmits the PRACH to the base station device via the identified RO.

Description

Terminal device, base station device, and wireless communication system

[0001] The present disclosure relates to a terminal device, a base station device, and a wireless communication system.

[0002] In today's networks, traffic from mobile devices (smartphones and feature phones) accounts for the majority of network resources, and this trend is expected to continue. In addition to traffic from mobile devices, IoT (Internet of Things) services (e.g., transportation systems, smart meters, and monitoring systems for devices) are also being developed. Therefore, these networks are being required to support services with diverse requirements.

[0003] In order to accommodate such diverse services, communication standards for fifth-generation mobile communications (5G or NR (New Radio)) (for example, Non-Patent Documents 1 to 14) have been developed that assume support for many use cases classified as, for example, eMBB (Enhanced Mobile Broadband), Massive MTC (Machine Type Communications), and URLLC (Ultra-Reliable and Low Latency Communications).

[0004] The 3rd Generation Partnership Project (3GPP), an international standardization project, is currently continuously studying and standardizing technologies to extend the above communication standards.

[0005] 3GPP TS 37.324 V17.0.03GPP TS 37.340 V18.0.03GPP TS 38.201 V18.0.03GPP TS 38.202 V18.1.03GPP TS 38.211 V18.1.03GPP TS 38.212 V18.1.03GPP TS 38.213 V18.1.03GPP TS 38.214 V18.1.03GPP TS 38.215 V18.1.03GPP TS 38.300 V18.0.03GPP TS 38.321 V18.0.03GPP TS 38.322 V18.0.03GPP TS 38.323 V18.0.03GPP TS 38.331 V18.0.0

[0006] In the wireless communication system described above, for example, terminal devices compatible with NES (Network Energy Saving) cells and terminal devices not compatible with NES cells may coexist. The NES cell is, for example, a cell to which a technology capable of reducing the power consumption of a base station device is applied. An example of a technology capable of reducing the power consumption of a base station is adjusting the resource cycle or the number of resources of a PRACH (Physical Random Access Channel). Another example of a technology capable of reducing the power consumption of a base station is muting the PRACH resources. Muting the PRACH resources means, for example, stopping reception on the PRACH resources.

[0007] However, for example, an operation method when a terminal device corresponding to an NES cell and a terminal device not corresponding to an NES cell each perform a random access procedure (RACH: Random Access CHannel procedure) to the NES cell is under consideration and has not yet been decided. Therefore, in a wireless communication system, for example, the result of mapping an RO (Rach Occasion) and an SSB (Synchronization Signal Block) may differ between a terminal device corresponding to an NES cell and a terminal device not corresponding to an NES cell, and one or more SSBs mapped by a terminal device corresponding to an NES cell in the same RO may differ from one or more SSBs mapped by a terminal device not corresponding to an NES cell. Therefore, in a wireless communication system, for example, a base station device that receives a PRACH (Physical Random Access Channel) may not be able to identify an SSB corresponding to the RO used to transmit the PRACH.

[0008] Therefore, one disclosure provides a terminal device, a base station device, and a wireless communication system that are capable of identifying an SSB corresponding to an RO used in transmitting a PRACH.

[0009] A terminal device that transmits a PRACH (Physical Random Access Channel) to a base station device includes: a receiving unit that receives first information on a first RO (Rach Occasion) that is available to each of the terminal device and another terminal device; and second information on a second RO that is available to the terminal device but not to the other terminal device; a control unit that identifies an RO assigned to the terminal device from the first RO and the second RO according to the second information or the first information and the second information; and a transmitting unit that transmits the PRACH to the base station device via the identified RO.

[0010] One disclosure makes it possible to identify the SSB corresponding to the RO used to transmit the PRACH.

[0011] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system 10. FIG. 2 is a diagram illustrating an example of the configuration of a terminal device 100. FIG. 3 is a diagram illustrating an example of the configuration of a base station device 200. FIG. 4 is a diagram illustrating a specific example of RO. FIG. 5 is a diagram illustrating a specific example of RO. FIG. 6 is a diagram illustrating a specific example of RO. FIG. 7 is a diagram illustrating a specific example of RO. FIG. 8 is a diagram illustrating an example of a sequence of a mapping control process in the first embodiment. FIG. 9 is a diagram illustrating an example of a sequence of a mapping control process in the first embodiment. FIG. 10 is a diagram illustrating a specific example of RO. FIG. 11 is a diagram illustrating a specific example of RO. FIG. 12 is a diagram illustrating a specific example of RO. FIG. 13 is a diagram illustrating a specific example of RO. FIG. 14 is a diagram illustrating an example of a sequence of a mapping control process in the first embodiment. FIG. 15 is a diagram illustrating a specific example of RO. FIG. 16 is a diagram illustrating a specific example of RO. FIG. 17 is a diagram illustrating a specific example of RO. FIG. 18 is a diagram illustrating a specific example of RO. FIG. 19 is a diagram illustrating a specific example of RO. 20 and 21 are diagrams illustrating specific examples of RO.

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, such descriptions should not be interpreted in a limiting sense, and do not limit the subject matter described in the claims. Furthermore, various changes, substitutions, and modifications can be made without departing from the spirit and scope of the present disclosure. Furthermore, different embodiments can be combined as appropriate.

[0013] [First embodiment] (Regarding wireless communication system 10) Fig. 1 is a diagram showing an example of the configuration of a wireless communication system 10. The wireless communication system 10 includes, for example, a terminal device 100a, a terminal device 100b, and a base station device 200. Hereinafter, the terminal device 100a and the terminal device 100b will also be collectively referred to simply as the terminal device 100.

[0014] The terminal device 100a is, for example, a communication device that is wirelessly connected to the base station device 200 and transmits and receives data. Specifically, the terminal device 100a is, for example, a UE (User Equipment) such as a smartphone or a tablet terminal. The terminal device 100a is, for example, a terminal device 100 that corresponds to an NES cell. Hereinafter, the terminal device 100a is also referred to as an NES Capable UE. Hereinafter, the terminal device 100a is also simply referred to as an NES.

[0015] The terminal device 100b is, for example, a communication device that is wirelessly connected to the base station device 200 and transmits and receives data. Specifically, the terminal device 100b is, for example, a UE (User Equipment) such as a smartphone or a tablet terminal. The terminal device 100b is, for example, a terminal device 100 that does not support an NES cell. Hereinafter, the terminal device 100b is also referred to as a Legacy UE. Hereinafter, the terminal device 100b is also simply referred to as a LEG.

[0016] The base station device 200 is, for example, a device that is wirelessly connected to the terminal device 100 and transmits and receives data. Specifically, the base station device 200 is, for example, an eNodeB or a gNodeB. The base station device 200 supports, for example, various communication generations (for example, 4G, 5G, Beyond 5G, or 6G). Furthermore, the base station device 200 may be, for example, configured as a single device, or may be configured as a plurality of devices such as a CU (Central Unit) and a DU (Distributed Unit).

[0017] 2 is a diagram showing an example of the configuration of the terminal device 100. The terminal device 100 includes, for example, a CPU (Central Processing Unit) 110, a storage 120, a memory 130, and a wireless communication circuit 150.

[0018] The storage 120 is, for example, an auxiliary storage device that stores programs and data, and is a flash memory, a hard disk drive (HDD), a solid state drive (SSD), etc. The storage 120 stores, for example, a terminal communication program 121 and a mapping control program 122.

[0019] The memory 130 is, for example, an area into which programs stored in the storage 120 are loaded. Note that the memory 130 may also be used, for example, as an area into which programs store data.

[0020] The wireless communication circuit 150 is, for example, a circuit that performs wireless communication with the base station device 200. The wireless communication circuit 150 has, for example, an antenna 151. The antenna 151 includes, for example, a directional antenna that can control the direction of transmission and reception of radio waves. The wireless communication circuit 150 is also, for example, capable of changing transmission power.

[0021] The CPU 110 is a processor that, for example, loads a program stored in the storage 120 into the memory 130 and executes it to configure each unit and realize each process.

[0022] The CPU 110 executes, for example, the terminal communication program 121 to configure a receiving unit and a transmitting unit and perform terminal communication processing. The terminal communication processing is processing for establishing a wireless connection with the base station device 200 and performing wireless communication.

[0023] The CPU 110 executes the mapping control program 122 to build a mapping control unit (hereinafter also simply referred to as a control unit) and perform mapping control processing. The mapping control processing is processing for mapping (associating) an RO (Ratch Occasion) with an SSB (Synchronization Signal Block), for example.

[0024] 3 is a diagram showing an example of the configuration of the base station device 200. The base station device 200 includes a CPU 210, a storage 220, a memory 230, and a wireless communication circuit 250, for example.

[0025] The storage 220 is, for example, an auxiliary storage device that stores programs and data, and is a flash memory, HDD, SSD, etc. The storage 220 stores, for example, a base station communication program 221.

[0026] The memory 230 is, for example, an area into which programs stored in the storage 220 are loaded. Note that the memory 230 may also be used, for example, as an area into which programs store data.

[0027] The wireless communication circuit 250 is, for example, a device that performs wireless communication with the terminal device 100. The wireless communication circuit 250 has, for example, an antenna 251. The antenna 251 includes, for example, a directional antenna that can control the direction of transmission and reception of radio waves.

[0028] The CPU 210 is a processor that, for example, loads a program stored in the storage 220 into the memory 230 and executes it to configure each unit and realize each process.

[0029] The CPU 210 executes, for example, the base station communication program 221 to configure a receiving unit and a transmitting unit and perform base station communication processing. The base station communication processing is processing for performing wireless communication with the terminal device 100. Specifically, in the base station communication processing, the base station device 200 establishes a wireless connection with the terminal device 100, transmits data to the terminal device 100, and receives data from the terminal device 100.

[0030] (Specific Examples of RO) Next, specific examples of RO will be described. Figures 4 to 7, 10 to 13, and 15 to 18 are diagrams for explaining specific examples of RO. In Figures 4 to 7, 10 to 13, and 15 to 18, the horizontal axis corresponds to time and the vertical axis corresponds to frequency.

[0031] The base station device 200 broadcasts, for example, information related to ROs. The information related to ROs includes, for example, information on time domain resources, information on frequency domain resources, the number of SSBs allocated per RO, and the number of preambles for each SSB per RO. The information on time domain resources is provided, for example, by a PRACH configuration index. The information on frequency domain resources is provided, for example, by the number of FDMs (Frequency Division Multiplexes). The number of FDMs is the number of ROs allocated at the same time.

[0032] Specifically, the base station device 200 broadcasts information (hereinafter also referred to as first information) regarding an RO (hereinafter also referred to as the first RO) that can be used when transmitting a PRACH by, for example, a terminal device corresponding to the NES cell (e.g., terminal device 100a) and a terminal device not corresponding to the NES cell (e.g., terminal device 100b).

[0033] In addition, the base station device 200 broadcasts information (hereinafter also referred to as second information) regarding an RO (hereinafter also referred to as second RO) that can be used by a terminal device (e.g., terminal device 100a) corresponding to the NES cell when transmitting a PRACH, but cannot be used by a terminal device (e.g., terminal device 100b) that does not correspond to the NES cell when transmitting a PRACH.

[0034] Hereinafter, a resource corresponding to the first RO will also be referred to as a resource LR, and a resource corresponding to the second RO will also be referred to as a resource AR. That is, in the example shown in Figure 4, the ROs included in resource LR1 ("RO0", "RO1", "RO2", and "RO3") and the ROs included in resource LR2 ("RO8", "RO9", "RO10", and "RO11") are first ROs. Also, in the example shown in Figure 4, the ROs included in resource AR1 ("RO4", "RO5", "RO6", and "RO7") and the ROs included in resource AR2 ("RO12", "RO13", "RO14", and "RO15") are second ROs.

[0035] Here, the terminal device 100a is, for example, the terminal device 100 that can recognize each of the first information and the second information. That is, the terminal device 100a is, for example, the terminal device 100 that can transmit a PRACH by using each of the first RO and the second RO. Therefore, when mapping ROs and SSBs, for example, the terminal device 100a maps each SSB to "RO0," "RO1," "RO2," "RO3," "RO4," "RO5," "RO6," "RO7," "RO8," "RO9," "RO10," "RO11," "RO12," "RO13," "RO14," and "RO15," as shown in FIG. 5 .

[0036] Specifically, for example, when the number of SSBs allocated per RO is set to 1, the terminal device 100a sequentially associates "SSB0," "SSB1," "SSB2," "SSB3," "SSB4," "SSB5," "SSB6," and "SSB7" with "RO0," "RO1," "RO2," "RO3," "RO4," "RO5," "RO6," and "RO7," respectively, as shown in Figure 5. Furthermore, the terminal device 100a sequentially associates "SSB0," "SSB1," "SSB2," "SSB3," "SSB4," "SSB5," "SSB6," and "SSB7" with "RO8," "RO9," "RO10," "RO11," "RO12," "RO13," "RO14," and "RO15," respectively.

[0037] In contrast, the terminal device 100b is, for example, a terminal device 100 that can recognize the first information but cannot recognize the second information due to a difference in the supported version of the program. That is, the terminal device 100b is, for example, a terminal device 100 that can transmit a PRACH using the first RO but cannot transmit a PRACH using the second RO. Therefore, when mapping ROs and SSBs, the terminal device 100b maps each SSB to "RO0," "RO1," "RO2," "RO3," "RO8," "RO9," "RO10," and "RO11," as shown in FIG. 6 .

[0038] Specifically, as shown in Figure 6, the terminal device 100a associates, for example, "RO0", "RO1", "RO2", "RO3", "RO8", "RO9", "RO10", and "RO11" with "SSB0", "SSB1", "SSB2", "SSB3", "SSB4", "SSB5", "SSB6", and "SSB7" in that order, respectively.

[0039] In other words, when mapping between RO and SSB is performed in each of terminal device 100a and terminal device 100b, for some ROs, the SSB mapped by terminal device 100a may be different from the SSB mapped by terminal device 100b.

[0040] 5 and 6 are performed in the terminal device 100a and the terminal device 100b, respectively, in the wireless communication system 10, as shown in Fig. 7, the SSBs mapped to "RO8," "RO9," "RO10," and "RO11" differ depending on the terminal device 100. Therefore, in the wireless communication system 10, for example, the base station device 200 that receives the PRACH may not be able to identify the SSB corresponding to the RO used to transmit the PRACH.

[0041] (Mapping Control Process in First Embodiment) Next, the mapping control process in the first embodiment will be described. Fig. 8 is a diagram showing an example of the sequence of the mapping control process in the first embodiment. Figs. 9 and 14 are flowcharts of the mapping control process in the first embodiment. Figs. 10 to 13 and 15 to 18 are diagrams for explaining the mapping control process in the first embodiment.

[0042] The terminal device 100a measures, for example, the RSRP (Reference Signal Received Power) of one or more SSBs broadcast from the base station device 200 (S11).

[0043] Then, the terminal device 100a performs a process of selecting an SSB with the highest measured RSRP from one or more SSBs (hereinafter also referred to as an SSB selection process) (S12).

[0044] Next, the terminal device 100a receives, for example, notification information broadcast from the base station device 200 (S13). The notification information is, for example, information transmitted via SIB1 (System Information Block Type 1). The notification information is, for example, RRC information. The RRC information is, for example, information included in RRCReconfiguration, RRCResume, RRCSetup, or ReconfigurationWithSync. Specifically, the notification information may include, for example, first information and second information. Note that the first information and the second information may each include, for example, different notification information.

[0045] Then, the terminal device 100a performs, for example, a process of determining the position (time position and frequency position) of each RO (hereinafter also referred to as RO position determination process) (S14).

[0046] Specifically, the terminal device 100a determines the time position of each RO by, for example, referring to the time domain resource information included in the first information or the second information, and also determines the frequency position of each RO by, for example, referring to the frequency domain resource information included in the first information or the second information.

[0047] Next, the terminal device 100a performs a process of mapping each of the first RO and the second RO with the SSB (hereinafter also referred to as a mapping process) (S15).

[0048] Then, the terminal device 100a transmits a PRACH to the base station device 200, for example, in the RO corresponding to the SSB selected in S12 (S16).

[0049] Specifically, for example, in S16, the terminal device 100a transmits the PRACH by using a preamble randomly selected from the preambles mapped in S15 corresponding to the selected RO. Also, for example, the terminal device 100a transmits the PRACH by using a preamble specified by the notification information transmitted from the base station device 200.

[0050] (Details of S15 (1)) Next, details of S15 will be described. Fig. 9 is a flowchart illustrating a first specific example (hereinafter simply referred to as the first specific example) of details of S15. Figs. 10 to 12 are diagrams illustrating the first specific example.

[0051] As shown in Fig. 9, the terminal device 100a performs, for example, mapping between each of the first ROs and the SSB (S15-1). That is, the terminal device 100a performs, for example, mapping between ROs that can be used by a terminal device 100 that does not support NES (for example, the terminal device 100b) and the SSB. In other words, the terminal device 100a performs, for example, the same mapping as that performed in a terminal device 100 that does not support NES (for example, the terminal device 100b). Hereinafter, the result of the same mapping as that performed in a terminal device 100 that does not support NES (for example, the terminal device 100b) is also referred to as NES1.

[0052] Specifically, as shown in Fig. 10, the terminal device 100a associates "SSB0", "SSB1", "SSB2", "SSB3", "SSB4", "SSB5", "SSB6", and "SSB7" in order with, for example, "RO0", "RO1", "RO2", and "RO3" that are ROs included in resource LR21, and "RO8", "RO9", "RO10", and "RO11" that are ROs included in resource LR22. Note that the example shown in Fig. 10 is an example in which SSBs corresponding to one mapping cycle are associated.

[0053] Next, the terminal device 100a performs, for example, mapping between the first RO and the second RO and the SSB (S15-2). That is, the terminal device 100a performs, for example, mapping between ROs that the terminal device 100a can use and the SSB. Hereinafter, the mapping result performed by the terminal device 100a is also referred to as NES2.

[0054] Specifically, as shown in FIG. 4, the terminal device 100a associates, with an SSB, the ROs "RO0," "RO1," "RO2," and "RO3" included in resource LR21, the ROs "RO4," "RO5," "RO6," and "RO7" included in resource AR21, the ROs "RO8," "RO9," "RO10," and "RO11" included in resource LR22, and the ROs "RO12," "RO13," "RO14," and "RO15" included in resource AR22.

[0055] Next, the terminal device 100a performs mapping in each RO, for example, and then compares the results with the mapping results performed in the same RO in S15-1 (S15-3).

[0056] The terminal device 100a then identifies a valid RO (a valid RO for the terminal device 100a) based on, for example, a comparison result of the mapping results, and identifies the RO as valid unless the mapping results are different (S15-4).

[0057] Specifically, for example, as shown in Fig. 11, the terminal device 100a performs mapping with "RO0", and then compares the mapping result with the mapping result performed with "RO0" in S15-1, and identifies "RO0" as a valid RO since the mapping results are the same. Then, for example, the terminal device 100a identifies "RO1", "RO2", and "RO3" as valid ROs using the same procedure, as shown in Fig. 11.

[0058] 11, for example, after performing mapping in "RO4," the terminal device 100a compares the result of the mapping performed in "RO4" with the result of the mapping performed in "RO4" in S15-1, and since there is no mapping result in "RO4" in S15-1, the terminal device 100a identifies "RO4" as a valid RO. Then, for example, the terminal device 100a identifies "RO5," "RO6," and "RO7" as valid ROs using the same procedure, as shown in FIG.

[0059] Furthermore, as shown in FIG. 11, for example, after performing mapping with "RO8", the terminal device 100a compares the result of the mapping performed with "RO8" in S15-1 with the result of the mapping performed with "RO8" in S15-1, and since the result is different from the mapping result with "RO8" in S15-1, the terminal device 100a does not identify "RO8" as a valid RO.

[0060] In this way, the terminal device 100a identifies, for example, "RO0," "RO1," "RO2," "RO3," "RO4," "RO5," "RO6," "RO7," "RO12," "RO13," "RO14," and "RO15" as valid ROs and associates them with SSBs, as shown in Fig. 12. In other words, the terminal device 100a identifies, for example, ROs other than "RO8," "RO9," "RO10," and "RO11" as valid ROs and associates them with SSBs, as shown in Fig. 12.

[0061] In this way, the terminal device 100a in this embodiment receives, for example, first information on a first RO available to each of the terminal device 100a and the terminal device 100b, and second information on a second RO available to the terminal device 100a but not to the terminal device 100b. Then, the terminal device 100a in this embodiment identifies an RO allocated to the terminal device 100a from the first RO and the second RO, for example, in accordance with the first information and the second information. Thereafter, the terminal device 100a in this embodiment transmits a PRACH to the base station device 200 via the identified RO, for example.

[0062] That is, for example, the terminal device 100a does not determine, as a valid RO, an RO in which the result of mapping performed by the terminal device 100a and the result of mapping performed by the terminal device 100b differ.

[0063] This allows the wireless communication system 10 to perform control so that, for example, one or more SSBs mapped by the terminal device 100a and one or more SSBs mapped by the terminal device 100b in the same RO are not different. Therefore, in the wireless communication system 10, it is possible to prevent, for example, a situation from occurring in which the base station device 200 that has received the PRACH cannot identify the SSBs corresponding to the RO used to transmit the PRACH.

[0064] For example, if a first RO and a second RO (hereinafter also referred to as an overlapping RO) exist, the terminal device 100a may map the RO other than the overlapping RO between the first RO and the second RO and the SSB in S15-2. Specifically, for example, the terminal device 100a does not identify as a valid RO.

[0065] (Details of S15 (2)) Fig. 14 is a flowchart illustrating a second specific example (hereinafter simply referred to as the second specific example) of the details of S15. Figs. 15 to 17 are diagrams illustrating the second specific example.

[0066] The terminal device 100a performs, for example, mapping between each of the first ROs and the SSB (S15-5), as shown in Fig. 14. That is, the terminal device 100a performs, for example, the same process as S15-1.

[0067] Specifically, as shown in Fig. 15, the terminal device 100a associates "SSB0", "SSB1", "SSB2", "SSB3", "SSB4", "SSB5", "SSB6", and "SSB7" in order with, for example, "RO0", "RO1", "RO2", and "RO3" that are ROs included in resource LR31, and "RO8", "RO9", "RO10", and "RO11" that are ROs included in resource LR32. Note that the example shown in Fig. 15 is an example in which SSBs corresponding to one mapping cycle are associated.

[0068] Next, the terminal device 100a performs, for example, mapping between each of the second ROs and the SSB (S15-6). That is, the terminal device 100a performs, for example, mapping between ROs that cannot be used by a terminal device 100 that does not support NES (for example, the terminal device 100b) and the SSB.

[0069] Specifically, as shown in Fig. 16, for example, the terminal device 100a associates "SSB0", "SSB1", "SSB2", "SSB3", "SSB4", "SSB5", "SSB6", and "SSB7" in order with "RO4", "RO5", "RO6", and "RO7" that are ROs included in resource AR31, and "RO12", "RO13", "RO14", and "RO15" that are ROs included in resource AR32. Note that the example shown in Fig. 16 is an example in which SSBs corresponding to one mapping cycle are associated.

[0070] Then, as shown in FIG. 17, the terminal device 100a associates the first RO and the second RO with the SSB, for example.

[0071] This allows the wireless communication system 10 to perform control so that, for example, one or more SSBs mapped by the terminal device 100a and one or more SSBs mapped by the terminal device 100b in the same RO are not different. Therefore, in the wireless communication system 10, it is possible to prevent, for example, a situation from occurring in which the base station device 200 that has received the PRACH cannot identify the type of the terminal device 100 that is the sender of the PRACH or the SSBs that correspond to the RO used to transmit the PRACH.

[0072] For example, if there is a duplicated RO, the terminal device 100a may map the ROs other than the duplicated RO among the second ROs to the SSB in S15-6. Specifically, for example, the terminal device 100a does not identify as a valid RO.

[0073] Second Embodiment Next, a second embodiment will be described.

[0074] The terminal device 100a in this embodiment transmits the PRACH by using a preamble designated in advance by the base station device 200 from among preambles available for use in the SSB selected in S12 or the like, for example.

[0075] Specifically, the terminal device 100a receives, for example, information indicating a preamble transmitted from the base station device 200 (hereinafter referred to as third information). Then, for example, as shown in FIG. 8, the terminal device 100a identifies a preamble indicated by the third information received from the base station device 200 from among preambles usable in the SSB selected in S12 or the like. Note that the terminal device 100a transmits the PRACH by using, for example, a preamble randomly selected from the identified preambles. Note that the third information may be included in, for example, notification information broadcast from the base station device 200. Furthermore, the terminal device 100a may transmit the PRACH by using, for example, the identified preamble.

[0076] More specifically, the third information includes the number of preambles (hereinafter also simply referred to as the number of preambles) available to the terminal device 100 (e.g., the terminal device 100a) corresponding to the NES, and the first index (hereinafter also simply referred to as the first index) of the preambles available to the terminal device 100 (e.g., the terminal device 100a) corresponding to the NES. Then, the terminal device 100a specifies, for example, a range equal to or greater than the first index and less than an index corresponding to the sum of the first index and the number of preambles, as the range of indexes for preambles available to the terminal device 100a. Note that the terminal device 100a may transmit the PRACH by using, for example, a preamble randomly selected from the preambles included in the specified range. Furthermore, the terminal device 100a may transmit the PRACH by using, for example, the specified preamble.

[0077] This allows the base station device 200 to identify the SSB corresponding to the RO used to transmit the PRACH, for example, by referring to the preamble corresponding to the PRACH. Also, the base station device 200 can identify, for example, the type of the terminal device 100 that is the source of the PRACH.

[0078] Third Embodiment Next, a third embodiment will be described. Figures 18 to 21 are diagrams for explaining specific examples of RO in the third embodiment.

[0079] The terminal device 100a in this embodiment associates the first RO and the second RO with the SSB so that the number of times the SSB mapping cycle is executed within the configuration period (hereinafter simply referred to as the configuration period) of the first RO is a predetermined integer number (hereinafter also referred to as the first integer number), and the number of times the SSB mapping cycle is executed within the configuration period of the second RO is another integer number (hereinafter also referred to as the second integer number). Each of the first integer number and the second integer number may be, for example, one or more.

[0080] Specifically, the terminal device 100a in this embodiment controls the number of times the SSB mapping cycle is executed within the setting period of the first RO to be a first integer number, for example, by referring to the number of SSBs allocated per RO included in the first information and the second information, and controls the number of times the SSB mapping cycle is executed within the setting period of the second RO to be a second integer number.

[0081] More specifically, in the example shown in FIG. 18, for example, each RO included in resource LR41 ("RO0", "RO1", "RO2", and "RO3"), each RO included in resource AR41 ("RO4", "RO5", "RO6", and "RO7"), each RO included in resource LR42 ("RO8", "RO9", "RO10", and "RO11"), and each RO included in resource AR42 ("RO12", "RO13", "RO14", and "RO15") each correspond to the set period.

[0082] Therefore, in this case, the terminal device 100a performs mapping in which "SSB0", "SSB1", "SSB2", "SSB3", "SSB4", "SSB5", "SSB6", and "SSB7", which correspond to one mapping cycle, are associated with each RO in each of the setting period consisting of resource LR41, the setting period consisting of resource AR41, the setting period consisting of resource LR42, and the setting period consisting of resource AR42.

[0083] In this case, the terminal device 100b performs mapping in which "SSB0", "SSB1", "SSB2", "SSB3", "SSB4", "SSB5", "SSB6", and "SSB7", which correspond to one mapping cycle, are associated with each RO, for example, in a setting period consisting of resource LR41 and a setting period consisting of resource LR42.

[0084] In addition, in the example shown in Figure 19, each RO included in resource LR51 and resource LR52 ("RO0", "RO1", "RO2", "RO3", "RO4", "RO5", "RO6", and "RO7"), each RO included in resource AR51 and resource AR52 ("RO8", "RO9", "RO10", "RO11", "RO12", "RO13", "RO14", and "RO15"), and each RO included in resource LR53 and resource LR54 ("RO16", "RO17", "RO18", "RO19", "RO20", "RO21", "RO22", and "RO23") each correspond to the set period.

[0085] Therefore, in this case, the terminal device 100a performs mapping that associates "SSB0", "SSB1", "SSB2", "SSB3", "SSB4", "SSB5", "SSB6", and "SSB7", which correspond to one mapping cycle, with each RO, for example, in a setting period consisting of resource LR51 and resource LR52, a setting period consisting of resource AR51 and resource AR52, and a setting period consisting of resource LR53 and resource LR54.

[0086] In this case, the terminal device 100b performs mapping in which "SSB0", "SSB1", "SSB2", "SSB3", "SSB4", "SSB5", "SSB6", and "SSB7", which correspond to one mapping cycle, are associated with each RO, for example, in a setting period consisting of resources LR51 and LR52 and a setting period consisting of resources LR53 and LR54.

[0087] This allows the wireless communication system 10 to perform control so that, for example, one or more SSBs mapped by the terminal device 100a and one or more SSBs mapped by the terminal device 100b in the same RO are not different. Therefore, the wireless communication system 10 can prevent, for example, a situation in which the base station device 200 that has received the PRACH cannot identify the SSBs corresponding to the RO used to transmit the PRACH.

[0088] Note that, for example, from the viewpoint of reducing power consumption, the base station device 200 can adjust the setting period of the second RO or the number of ROs included in the second RO, or mute some of the second ROs. Muting some of the second ROs means stopping reception of some of the second ROs.

[0089] Specifically, as shown in Fig. 20, the base station device 200 can, for example, mute each RO in resource AR51. To this end, the base station device 200 notifies the terminal device 100a that each RO in resource AR51 will be muted, for example, by using an RRC message, a MAC Control Element (MAC-CE), or Downlink Control Information (DCI). Furthermore, as shown in Fig. 21, the base station device 200 can, for example, transmit first information that does not include information related to each RO in resource AR51, or omit transmitting the first information.

[0090] 20, for example, the SSB corresponding to the terminal device 100 (e.g., terminal device 100a) that supports NES and the SSB corresponding to the terminal device 100 (e.g., terminal device 100b) that does not support NES are different in resource LR 53 and resource LR 54. On the other hand, in the example shown in FIG. 21, for example, the SSB corresponding to the terminal device 100 (e.g., terminal device 100a) that supports NES and the SSB corresponding to the terminal device 100 (e.g., terminal device 100b) that does not support NES are the same in resource LR 53 and resource LR 54.

[0091] Therefore, when notifying that some second ROs will be performed, the base station device 200 notifies that ROs within a resource AR included in an integer number of setting periods (e.g., one) will be muted, as shown in Fig. 21. Also, the base station device 200 notifies that second ROs corresponding to an integer number of mapping cycles (e.g., one) will be muted, for example.

[0092] Specifically, the base station device 200 broadcasts, for example, information related to RO adjustment to the terminal device 100a in the second information. The information related to RO adjustment is, for example, information including a second RO configuration period, the number of ROs corresponding to the second ROs, and at least one pattern for muting some of the second ROs. The pattern for muting some of the second ROs is, for example, muting second ROs corresponding to an integer number of mapping cycles (for example, one). The pattern for muting some of the second ROs is, for example, muting second ROs included in an integer number of configuration periods (for example, one).

[0093] Then, the base station device 200 notifies the terminal device 100a of the configuration period of the second RO to be applied to the terminal device 100a, or / and the number of ROs corresponding to the second RO, or / and a pattern for muting some of the second ROs, using, for example, an RRC message, a MAC Control Element (MAC-CE), or Downlink Control Information (DCI).

[0094] This makes it possible for the wireless communication system 10 to prevent a situation from occurring in which, for example, the base station device 200 that receives the PRACH is unable to identify the SSB corresponding to the RO used to transmit the PRACH, even when transmitting first information in which information regarding at least some of the resource AR is omitted.

[0095] [Modifications of the First to Third Embodiments] Next, modifications of the first to third embodiments will be described.

[0096] For example, the terminal device 100a may not identify an RO designated in advance by the base station device 200 as a valid RO.

[0097] Specifically, the terminal device 100a may receive, for example, information indicating an RO (hereinafter referred to as fourth information) transmitted from the base station device 200. Then, the terminal device 100a may identify, for example, an RO other than the RO indicated by the fourth information as a valid RO for the terminal device 100a.

[0098] 10: Wireless communication system 100: Terminal device 100a: Terminal device 100b: Terminal device 110: CPU 120: Storage 121: Terminal communication program 122: Mapping control program 130: Memory 150: Wireless communication circuit 151: Antenna 200: Base station device 210: CPU 220: Storage 221: Base station communication program 230: Memory 250: Wireless communication circuit 251: Antenna

Claims

1. A terminal device that transmits a PRACH (Physical Random Access Channel) to a base station device, comprising: a receiver that receives first information regarding a first RO (Rach Occasion) that is available to each of the terminal device and another terminal device, and second information regarding a second RO that is available to the terminal device but not to the other terminal device; a controller that identifies an RO assigned to the terminal device from the first RO and the second RO according to the second information or the first information and the second information; and a transmitter that transmits the PRACH to the base station device via the identified RO.

2. The terminal device according to claim 1, wherein the control unit identifies a specific RO among the first RO and the second RO, in which the SSB (Synchronization Signal Block) associated with each RO by the terminal device is different from the SSB associated with each RO by the other terminal device, and identifies an RO other than the identified specific RO as the RO assigned to the terminal device.

3. The terminal device according to claim 2, wherein the control unit associates the SSB corresponding to a first mapping cycle with the first RO, and associates the SSB corresponding to a second mapping cycle different from the first mapping cycle with the second RO.

4. The terminal device according to claim 1, wherein the receiving unit receives third information regarding a preamble from the base station device, and the transmitting unit transmits the PRACH to the base station device by using a preamble corresponding to the third information.

5. The terminal device according to claim 1, wherein the control unit associates the first RO and the second RO with the SSB so that the number of times an SSB mapping cycle is executed within the setting period of the first RO is a first integer number, and the number of times an SSB mapping cycle is executed within the setting period of the second RO is a second integer number.

6. The terminal device according to claim 1, wherein the receiving unit receives fourth information from the base station device indicating a specific RO that cannot be assigned to the terminal device, and the control unit identifies an RO other than the specific RO indicated by the fourth information as the RO assigned to the terminal device.

7. A base station device comprising: a transmitter that transmits first information regarding a first RO that is available to each of a first terminal device and a second terminal device; and second information regarding a second RO that is available to the first terminal device but not to the second terminal device; and a receiver that receives a PRACH from the first terminal device via the second information or an RO identified in accordance with the first information and the second information.

8. A wireless communication system having a first terminal device and a base station device, wherein the base station device has a transmitter that transmits first information regarding a first RO that is available to each of the first terminal device and a second terminal device, and second information regarding a second RO that is available to the first terminal device but not to the second terminal device; and the first terminal device identifies an RO assigned to the first terminal device from the first RO and the second RO according to the second information or the first information and the second information, and transmits a PRACH (Physical Random Access CHannel) to the base station device via the identified RO.

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