Base station, communication method and integrated circuit

Abstract

To improve the efficiency of random access processing.SOLUTION: A base station includes a receiver that receives a random access signal including a preamble portion and a data portion from a terminal device, and a transmitter that transmits a MAC layer protocol data unit (PDU) including a response to the random access signal after receiving the random access signal, the MAC layer PDU including transmission timing information for uplink transmission.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a terminal and a communication method. [Background technology]

[0002] The 3GPP (3rd Generation Partnership Project) has completed the formulation of the Release 15 NR (New Radio access technology) specifications to realize 5th generation mobile communication systems (5G). NR supports functions that realize ultra-reliable and low-latency communication (URLLC) in addition to high speed and large capacity, which are the basic requirements for enhanced mobile broadband (eMBB) (see, for example, Non-Patent Documents 1-7). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TS 38.211 V15.4.0, "NR; Physical channels and modulation (Release 15)," December 2018 [Non-patent document 2] 3GPP TS 38.212 V15.4.0, "NR; Multiplexing and channel coding (Release 15)," December 2018 [Non-patent document 3] 3GPP TS 38.213 V15.4.0, "NR; Physical layer procedure for control (Release 15)," December 2018 [Non-patent document 4] 3GPP TS 38.214 V15.4.0, "NR; Physical layer procedures for data (Release 15)," December 2018 [Non-patent document 5] 3GPP, TS38.300 V15.4.0, “NR; NR and NG-RAN overall description; Stage 2 (Release 15)”, December 2018 [Non-patent document 6] 3GPP, TS38.321 V15.4.0, “NR; Medium accesses control (MAC) protocol specification (Release 15)”, December 2018 [Non-Patent Document 7] 3GPP, TS38.331 V15.4.0, “NR; Radio resource control (RRC) protocol specification (Release 15)”, December 2018 [Non-patent document 8] B. Bertenyi, S. Nagata, H. Kooropaty, X. Zhou, W. Chen, Y. Kim, X. Dai, and X. Xu, “5G NR radio interface,” Journal of ICT, Vol. 6 and 2, pp. 31-58, 2018 [Non-Patent Document 9] RP-182881, “New work item: 2-step RACH for NR,” ZTE Corporation, Sanechips, December 2018 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the random access procedure in NR has not been thoroughly studied.

[0005] Non-limiting examples of the present disclosure contribute to providing a terminal and a communication method that can improve the efficiency of random access processing. [Means for solving the problem]

[0006] A terminal according to one embodiment of the present disclosure includes a control circuit that dynamically determines parameters related to transmission of a data portion of a random access signal including a preamble portion and a data portion, and a transmission circuit that notifies a base station of the determined parameters using the random access signal.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. [Effects of the Invention]

[0008] According to an embodiment of the present disclosure, the efficiency of random access processing can be improved.

[0009] Further advantages and benefits of an embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features. [Brief explanation of the drawings]

[0010] [Figure 1] A diagram showing an example of a four-step random access procedure [Figure 2] Diagram showing an example of a two-step random access procedure [Figure 3] FIG. 1 is a block diagram showing a configuration example of a portion of a terminal according to a first embodiment; [Figure 4] FIG. 1 is a block diagram showing a configuration example of a base station according to a first embodiment; [Figure 5] FIG. 1 is a block diagram showing a configuration example of a terminal according to a first embodiment; [Figure 6] A sequence diagram showing an example of the operation of a base station and a terminal according to the first embodiment. [Figure 7] FIG. 10 is a diagram showing an example of association between TBSs and RACH preamble resource groups according to the first embodiment; [Figure 8] An example of Message B [Figure 9] Another example of Message B [Figure 10] Diagram showing an example of a two-step random access procedure [Figure 11] Diagram showing an example of a two-step random access procedure [Figure 12] FIG. 10 is a diagram showing an example of association between transmission parameters and RACH preamble resource groups according to the second embodiment; [Figure 13] FIG. 10 is a diagram showing an example of association between transmission parameters and RACH preamble resource groups according to the second embodiment; [Figure 14] FIG. 10 is a diagram showing an example of association between transmission parameters and RACH preamble resource groups according to the second embodiment; [Figure 15] FIG. 10 is a diagram showing an example of association between transmission parameters and RACH preamble resource groups according to the second embodiment; [Figure 16] A sequence diagram showing an example of the operation of a base station and a terminal according to the third embodiment. [Figure 17] FIG. 13 is a diagram showing an example of association between TBS and UCI according to the third embodiment. [Figure 18] FIG. 13 is a diagram showing an example of association between TBS and UCI according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] In Release 15 NR, a terminal (also called a mobile station or UE: User Equipment) transmits a random access channel signal (RACH: Random Access Channel) to a base station (also called a gNB or eNB) in, for example, the following cases. (1) At initial access (e.g., transition from the RRC_IDLE state to the RRC_CONNECTED state) (2) When resuming from the RRC_INACTIVE state to the RRC_CONNECTED state (3) When downlink data or uplink data occurs during connection (e.g., when the uplink synchronization state is "non - synchronized" in the RRC_CONNECTED state) (4) When requesting on - demand SI (System Information) (5) When recovering from beam connection failure (BFR: Beam failure recovery)

[0013] Thereby, an attempt is made to establish a connection or resynchronization from the terminal to the base station. The series of operations performed for establishing such a connection or resynchronization from the terminal to the base station is called the "Random access procedure".

[0014] In Release 15 NR, the Random access procedure consists of, for example, four steps as shown in FIG. 1 (referred to as the 4 - step Random access procedure or 4 - step RACH procedure) (see, for example, Non - Patent Document 8).

[0015] <Step 1: Transmission of Message 1> The terminal (e.g., UE) randomly selects the RACH preamble resource to be actually used from a group of RACH preamble resource candidates (e.g., resources defined by a combination of time resource, frequency resource, and sequence resource). Then, the terminal transmits a RACH preamble (also simply called a preamble) to the base station (e.g., gNB) using the selected RACH preamble resource. The RACH preamble may be called, for example, "Message 1".

[0016] <Step 2: Transmission of Message 2> When the base station detects a RACH preamble, it transmits a RACH response (RAR: Random Access Response). The RAR may be called, for example, "Message 2". At this point, the base station cannot identify the terminal that transmitted the RACH preamble. Therefore, the RAR is transmitted, for example, to the entire cell covered by the base station.

[0017] The RAR includes, for example, information regarding the resources (uplink resources) used by the terminal in the transmission of the uplink signal (Step 3: Transmission of Message 3), or information regarding the transmission timing of the uplink by the terminal. Here, if the terminal that transmitted the RACH preamble does not receive the RAR within a period defined from the transmission timing of the RACH preamble (e.g., called the RAR reception window), it selects the RACH preamble resource again and transmits the RACH preamble (in other words, re-transmits Message 1).

[0018] <Step 3: Transmission of Message 3> The terminal transmits "Message 3" including, for example, an RRC (Radio Resource Control) connection request or a scheduling request, etc., using the uplink resources indicated by the base station in the RAR.

[0019] <Step 4: Transmission of Message 4> The base station transmits a message (referred to as "Message 4") including identification information (e.g., UE-ID) for identifying the terminal to the terminal. By transmitting Message 4, the base station confirms that multiple terminals are not in contention (contention resolution). Note that, for example, C-RNTI (Cell-Radio Network Temporary Identifier) or Temporary C-RNTI etc. may be used as the UE-ID.

[0020] The above has described an example of the 4-step Random access procedure.

[0021] On the other hand, in Release 16 NR, in order to efficiently establish connection or resynchronization from the terminal to the base station with low latency, for example, a Random access procedure (also referred to as 2-step Random access procedure or 2-step RACH procedure) composed of 2 steps shown in FIG. 2 is being considered (see, for example, Non-Patent Document 9).

[0022] <Step 1: Transmission of Message A> The terminal transmits a message (hereinafter referred to as "Message A") including information corresponding to Message 1 (in other words, preamble) and Message 3 corresponding to Steps 1 and 3 of the 4-step Random access procedure (see, for example, FIG. 1) to the base station.

[0023] <Step 2: Transmission of Message B> If the base station detects Message A, it transmits Message B. Message B includes, for example, information equivalent to (e.g., either or both of) Message 2 or Message 4 of the four-step random access procedure (see, for example, FIG. 1).

[0024] It is desirable that the two-step random access procedure be designed to be applicable to major use cases, such as eMBB, URLCC, and support for multiple MTC (Machine Type Communication) terminals (mMTC: massive MTC), which are envisioned for 5G, or to both licensed and unlicensed bands.

[0025] Here, in the Random access procedure, in the uplink transmission of Message 3, in addition to signals for controlling communications such as an RRC connection request or a scheduling request (e.g., also referred to as C-plane (Control-plane) data), the terminal transmits user (UP: User Plane) data that it actually wants to transmit to the base station, thereby achieving low-latency uplink data transmission.

[0026] For example, Release 16 is expected to support the transmission of UP data (also called PUSCH (Physical Uplink Shared Channel)) in a two-step random access procedure in the RRC_CONNECTED state (see, for example, Non-Patent Document 9). Note that support for the transmission of UP data in a two-step random access procedure in the RRC_IDLE state or the RRC_INACTIVE state is not within the scope of consideration in Release 16. However, the state of a terminal when the terminal starts a two-step random access procedure is not limited to the RRC_CONNECTED state.

[0027] The following describes the case where the 2-step random access procedure supports the transmission of UP data.

[0028] In the four-step random access procedure, as described above, the terminal transmits Message 3 using uplink resources instructed by the base station by the RAR. At this time, the terminal can include UP data in Message 3 in addition to C-plane data such as an RRC connection request or a scheduling request.

[0029] Here, the RAR contains information about resources used by the terminal in the uplink (for example, the location of time or frequency resources, the amount of resources (or resource size), and MCS (Modulation and Coding Scheme)). The terminal uses the information about the resources to determine the transport block size (TBS) for uplink transmission (see, for example, Non-Patent Documents 3 and 4). In this way, in the 4-step random access procedure, the base station can use the RAR to control uplink UP data transmission to the terminal, and can therefore correctly demodulate and decode Message 3 transmitted from the terminal.

[0030] On the other hand, in the two-step random access procedure, the terminal transmits signals (e.g., referred to as a RACH data portion or simply a data portion) corresponding to Message 1 (e.g., a RACH preamble) and Message 3 of the four-step random access procedure in Message A. Therefore, when the terminal transmits UP data in Message A, the terminal transmits the UP data in the data portion of Message A without information on resources to be used in the uplink (in other words, a UL grant) included in an instruction (e.g., an RAR) from the base station.

[0031] Here, as an example, a method can be considered in which information regarding the resources to be used for the data portion of Message A transmitted by the terminal (e.g., the location of time and frequency resources, the amount of resources, and MCS) is semi-statically set in advance in the terminal by broadcast information from the base station or a higher layer signal (e.g., an RRC signal), thereby supporting the transmission of a fixed TBS.

[0032] However, as mentioned above, it is desirable for the two-step random access procedure to be designed so that it can be commonly applied to all 5G use cases, and it is expected that the amount of uplink UP data transmitted by a terminal will not be fixed but will vary depending on the use case.

[0033] Even within a single use case, traffic may vary depending on the assumed service. For example, in URLLC, Release 15 assumes packet transmission of 32 bytes, while Release 16 is expected to expand URLLC services and assumes packet transmission of larger packet sizes (e.g., 256 bytes).

[0034] When the amount of uplink UP data transmitted by a terminal is variable, a method that supports transmission of a fixed TBS lacks flexibility in uplink resource allocation.

[0035] The two-step random access procedure is particularly effective for low-latency use cases. In this case, if uplink resources are not allocated sufficiently for the amount of UP data transmitted by the terminal, segmentation of the UP data occurs. In this case, UP data that cannot be transmitted using the two-step random access procedure is held until the next opportunity for uplink data transmission. As a result, a long delay occurs before the UP data transmission is completed, which may make it impossible to meet the low-latency requirements of URLLC.

[0036] Another possible method is to set a fixed uplink resource (e.g., TBS) according to the maximum amount of UP data that a terminal is expected to transmit. However, this method requires a large amount of radio resources to be reserved for the two-step random access procedure, which reduces resource utilization efficiency.

[0037] Therefore, in one embodiment of the present disclosure, a method for improving the efficiency of uplink transmission in a two-step random access procedure will be described.

[0038] Each embodiment will be described in detail below.

[0039] (Embodiment 1) [Communication System Overview] A communication system according to each embodiment of the present disclosure includes a base station 100 and a terminal 200.

[0040] 3 is a block diagram showing a configuration example of a portion of terminal 200 according to each embodiment of the present disclosure. In terminal 200 shown in FIG. 3, control unit 209 (corresponding to a control circuit) dynamically determines parameters (e.g., TBS, etc.) related to transmission of a data portion of a random access signal (e.g., corresponding to Message A) including a preamble portion (e.g., corresponding to the RACH preamble of Message A) and a data portion (e.g., corresponding to the data portion of Message A). Transmitting unit 217 (equivalent to a transmitting circuit) notifies base station 100 of the determined parameters using the random access signal.

[0041] [Base station configuration] 4 is a block diagram showing an example configuration of a base station 100 according to embodiment 1 of the present disclosure. In FIG. 4, the base station 100 includes a control unit 101, a data generation unit 102, an encoding unit 103, a modulation unit 104, an upper control signal generation unit 105, an encoding unit 106, a modulation unit 107, a downlink control signal generation unit 108, an encoding unit 109, a modulation unit 110, a signal allocation unit 111, an IFFT (Inverse Fast Fourier Transform) unit 112, a transmission unit 113, an antenna 114, a reception unit 115, an FFT (Fast Fourier Transform) unit 116, an extraction unit 117, a detection unit 118, a demodulation unit 119, and a decoding unit 120.

[0042] Control unit 101 determines information for transmitting Message A from terminal 200, and outputs the determined information to extraction unit 117, demodulation unit 119, and decoding unit 120. Control unit 101 also outputs the determined information to higher-level control signal generation unit 105.

[0043] The information for transmitting Message A may include, for example, information about the TBS of the data portion of Message A, information about the correspondence between the TBS and the RACH preamble resource candidate set of Message A, or information about the correspondence between the resource candidates of the data portion of Message A (e.g., at least one of the resource position and the resource amount) and the RACH preamble resource candidate set of Message A.

[0044] Furthermore, the control unit 101 determines radio resource allocation (e.g., downlink resources and MCS) for downlink signals for transmitting a data signal (e.g., Message B), a control signal of an upper layer (e.g., an upper control signal), or downlink control information (e.g., a downlink control signal). The control unit 101 outputs the determined information to the coding units 103, 106, and 109, the modulation units 104, 107, and 110, and the signal allocation unit 111. The control unit 101 also outputs the determined information to the downlink control signal generation unit 108.

[0045] In addition, the control unit 101 determines the information to be included in Message B based on the decoding result of Message A (e.g., C-Plane data or UP data) input from the decoding unit 120 and the detection result of Message A (e.g., RACH preamble) input from the detection unit 118, and outputs the determined information to the data generation unit 102.

[0046] The data generation unit 102 generates an information bit string (in other words, downlink data) for Message B using the information to be included in Message B input from the control unit 101, and outputs the generated information bit string to the encoding unit 103.

[0047] Encoding section 103 performs error coding on the information bit string (data signal) input from data generating section 102 and outputs the coded data signal to modulation section 104.

[0048] Modulation section 104 modulates the data signal inputted from encoding section 103 and outputs the modulated data signal to signal allocation section 111 .

[0049] Higher-order control signal generating section 105 generates a control information bit string (higher-order control signal) using the control information input from control section 101, and outputs the generated control information bit string to encoding section .

[0050] Encoding section 106 performs error correction coding on the control information bit string inputted from higher-order control signal generating section 105 and outputs the coded control signal to modulating section 107 .

[0051] Modulation section 107 modulates the control signal inputted from encoding section 106 and outputs the modulated control signal to signal allocation section 111 .

[0052] The downlink control signal generating unit 108 generates a control information bit sequence (downlink control signal, for example, DCI) using the control information input from the control unit 101, and outputs the generated control information bit sequence to the encoding unit 109. Note that, since control information may be transmitted to multiple terminals, the downlink control signal generating unit 108 may scramble the control information for each terminal (for example, PDCCH: Physical Downlink Control Channel) using identification information for all terminals (for example, RA-RNTI: Random Access-RNTI) or identification information specific to a terminal (for example, C-RNTI).

[0053] Encoding section 109 performs error correction coding on the control information bit string inputted from downlink control signal generating section 108 and outputs the coded control signal to modulation section 110 .

[0054] Modulation section 110 modulates the control signal inputted from encoding section 109 and outputs the modulated control signal to signal allocation section 111 .

[0055] The signal allocation unit 111 maps the data signal input from the modulation unit 104, the higher control signal input from the modulation unit 107, or the downlink control signal input from the modulation unit 110 to the radio resources based on the information indicating the radio resources input from the control unit 101. The signal allocation unit 111 outputs the downlink signal onto which the signal has been mapped to the IFFT unit 112.

[0056] The IFFT unit 112 performs transmission waveform generation processing such as OFDM on the signal input from the signal allocation unit 111. In the case of OFDM transmission that adds a CP (Cyclic Prefix), the IFFT unit 112 adds a CP (not shown). The IFFT unit 112 outputs the generated transmission waveform to the transmission unit 113.

[0057] Transmitting section 113 performs RF (Radio Frequency) processing such as D / A (Digital-to-Analog) conversion and up-conversion on the signal input from IFFT section 112 , and transmits the radio signal to terminal 200 via antenna 114 .

[0058] The receiving unit 115 performs RF processing such as down-conversion or A / D (Analog-to-Digital) conversion on the uplink signal waveform from the terminal 200 received via the antenna 114, and outputs the uplink signal waveform after the receiving processing to the FFT unit 116.

[0059] The FFT unit 116 performs FFT processing to convert a time domain signal into a frequency domain signal on the uplink signal waveform input from the receiving unit 115. The FFT unit 116 outputs the frequency domain signal obtained by the FFT processing to the extracting unit 117.

[0060] Based on information input from the control unit 101, the extraction unit 117 extracts, from the signal input from the FFT unit 116, a radio resource portion on which a RACH preamble is transmitted, a radio resource portion on which UCI is transmitted, or a radio resource portion on which data of Message A is transmitted. The extraction unit 117 outputs the extracted radio resource portion on which the RACH preamble is transmitted to the detection unit 118, and outputs the extracted radio resource portion on which UCI is transmitted or the radio resource portion on which data of Message A is transmitted to the demodulation unit 119.

[0061] The detector 118 performs RACH preamble detection on the radio resource portion corresponding to the RACH preamble received as input from the extractor 117. The detector 118 outputs information on the detection result of the RACH preamble to the control unit 101.

[0062] Based on the information input from the control unit 101, the demodulation unit 119 demodulates the radio resource portion corresponding to the UCI or the radio resource portion corresponding to the data of Message A input from the extraction unit 117, and outputs the demodulation result (demodulation sequence) to the decoding unit 120.

[0063] The decoding unit 120 performs error correction decoding on the demodulation result input from the demodulation unit 119 based on the information input from the control unit 101, and outputs a decoded bit sequence (including, for example, UCI, C-Plane data, or UP data). For example, the decoding unit 120 outputs the obtained UCI to the control unit 101.

[0064] [Device configuration] 5 is a block diagram showing an example configuration of terminal 200 according to an embodiment of the present disclosure. In FIG. 5, terminal 200 includes antenna 201, receiving section 202, FFT section 203, extraction section 204, demodulation section 205, decoding section 206, downlink control signal demodulation section 207, decoding section 208, control section 209, RACH preamble generation section 210, coding section 211, modulation section 212, coding section 213, modulation section 214, signal allocation section 215, IFFT section 216, and transmission section 217.

[0065] The receiver 202 performs RF processing such as down-conversion or A / D (Analog-to-Digital) conversion on the signal waveform of the downlink signal from the base station 100 received via the antenna 201, and outputs the resulting received signal (baseband signal) to the FFT unit 203. The downlink signal includes, for example, a data signal (e.g., Message B), a higher-level control signal, or a downlink control signal.

[0066] FFT section 203 performs FFT processing on the signal (time domain signal) input from receiving section 202 to convert the time domain signal into a frequency domain signal. FFT section 203 outputs the frequency domain signal obtained by the FFT processing to extraction section 204.

[0067] Extraction section 204 extracts a data signal (e.g., Message B, etc.), a downlink control signal or a higher-level control signal from the signal input from FFT section 203, based on control information input from control section 209 (e.g., information related to the radio resource of the control signal). Extraction section 204 outputs the data signal or the higher-level control signal to demodulation section 205, and outputs the downlink control signal to downlink control signal demodulation section 207.

[0068] Demodulation section 205 demodulates the data signal or higher-level control signal input from extraction section 204 and outputs the demodulation result to decoding section 206 .

[0069] Decoding section 206 performs error correction decoding using the demodulation result input from demodulation section 205, and obtains received data (e.g., Message B) or control information. Decoding section 206 outputs the obtained received data or control information to control section 209.

[0070] The downlink control signal demodulation section 207 demodulates the downlink control signal inputted from the extraction section 204 and outputs the demodulation result to the decoding section 208 .

[0071] The decoding unit 208 obtains control information by performing error correction decoding using the demodulation result inputted from the downlink control signal demodulation unit 207. The decoding unit 208 outputs the obtained control information to the control unit 209.

[0072] The control unit 209 determines a transmission method or parameters (e.g., MCS or radio resources, etc.) for uplink transmission (e.g., transmission of Message A) based on control information input from the decoding unit 206 or the decoding unit 208. For example, the control unit 209 dynamically determines (or selects) parameters (e.g., TBS, etc.) related to the transmission of the data portion of Message A. The control unit 209 outputs the determined information to the RACH preamble generation unit 210, the coding units 211 and 213, the modulation units 212 and 214, and the signal allocation unit 215.

[0073] Furthermore, control section 209 outputs information relating to the radio resource of the control signal, which is included in the control information input from decoding section 206 or decoding section 208, to extraction section 204.

[0074] The RACH preamble generating section 210 generates a RACH preamble based on control information received as input from the control section 209 , and outputs the generated RACH preamble to the signal allocating section 215 .

[0075] When transmitting UCI to base station 100, encoding section 211 performs error correction encoding on the UCI (e.g., a UCI sequence) based on information input from control section 209, and outputs the encoded UCI (bit sequence) to modulation section 212.

[0076] Modulation section 212 modulates the UCI input from encoding section 211 based on information input from control section 209 , and outputs the modulated UCI (modulation symbol sequence) to signal allocation section 215 .

[0077] Based on information input from the control unit 209, the encoding unit 213 performs error correction encoding on an information bit sequence (e.g., UP data) transmitted in the data portion of Message A, and outputs the encoded bit sequence to the modulation unit 214.

[0078] Modulation section 214 modulates the bit sequence input from encoding section 213 based on information input from control section 209 , and outputs a data signal (modulation symbol sequence) to signal allocation section 215 .

[0079] The signal allocation unit 215 maps the signal input from the RACH preamble generation unit 210, the signal input from the modulation unit 212, or the signal input from the modulation unit 214 to the radio resources instructed by the control unit 209, and outputs the uplink signal onto which the signal is mapped to the IFFT unit 216.

[0080] IFFT unit 216 performs transmission waveform generation processing such as OFDM on the signal input from signal allocation unit 215. In the case of OFDM transmission that adds a CP (Cyclic Prefix), IFFT unit 216 adds a CP (not shown). Alternatively, in the case where IFFT unit 216 generates a single-carrier waveform, a DFT (Discrete Fourier Transform) unit may be added (not shown) before signal allocation unit 215. IFFT unit 216 outputs the generated transmission waveform to transmission unit 217.

[0081] The transmitter 217 performs RF processing such as D / A conversion and up-conversion on the signal input from the IFFT unit 216 , and transmits the radio signal to the base station 100 via the antenna 201 .

[0082] [Example of Operation of Base Station 100 and Terminal 200] An example of the operation of base station 100 and terminal 200 having the above configuration will be described.

[0083] In the following, it is assumed that the larger the TBS of the data portion of Message A, the greater the amount of resources required to transmit that data portion.

[0084] FIG. 6 shows an example of the flow of processing in base station 100 and terminal 200 according to this embodiment.

[0085] In this embodiment, information about the TBS in the data portion of Message A is associated with a group of RACH preamble resource candidates for Message A (for example, resources defined by a combination of time resources, frequency resources, and sequence resources).

[0086] Base station 100 generates, for example, information relating to the association between RACH preamble resource groups and transmission parameters (for example, TBS) of Message A, and notifies terminal 200 of the information (ST101). The information relating to the association between RACH preamble resource groups and transmission parameters of Message A may be notified from base station 100 to terminal 200 by, for example, higher layer signaling.

[0087] Terminal 200 acquires information relating to the association between RACH preamble resource groups and transmission parameters of Message A, which information has been notified from base station 100 (ST102). As a result, information relating to the association between RACH preamble resource groups and transmission parameters of Message A is shared between base station 100 and terminal 200.

[0088] FIG. 7 shows an example of association between TBSs and RACH preamble resource candidate sets (RACH preamble resource (set)).

[0089] 7, TBS=X1 is associated with RACH preamble resource candidate set Z1, TBS=X2 is associated with RACH preamble resource candidate set Z2, and TBS=X3 is associated with RACH preamble resource candidate set Z3. Note that the number of TBS candidates associated with the RACH preamble resource groups is not limited to three, and may be two or four or more.

[0090] When a transmission packet (in other words, an uplink signal) is generated, terminal 200 determines a TBS for the data portion of Message A (ST103). For example, a plurality of TBSs may be predefined in the standard as TBSs that terminal 200 can select from, or base station 100 may set a TBS using a higher layer signal (for example, an SIB (System Information Block) or a terminal-specific RRC signal). For example, terminal 200 dynamically determines a TBS for the data portion of Message A from among the defined or set TBSs.

[0091] In Fig. 6, terminal 200 determines a RACH preamble to transmit (ST104). For example, terminal 200 selects a RACH preamble resource to be used for transmission from a RACH preamble resource candidate group associated with the selected TBS, based on the association between the TBS and a RACH preamble resource candidate group. For example, in Fig. 7, when terminal 200 selects TBS=X2, it selects a RACH preamble resource to be used for transmitting the RACH preamble from RACH preamble resource candidate group Z2 associated with TBS=X2. The same applies when another TBS is selected in Fig. 7.

[0092] 6, terminal 200 generates Message A (ST105). For example, terminal 200 generates Message A including a signal of the data portion of Message A generated using the selected TBS (for example, at least one of C-Plane data and UP data) and a RACH preamble generated using the selected RACH preamble resource.

[0093] Terminal 200 transmits the generated Message A to base station 100 (ST106).

[0094] Base station 100 detects a RACH preamble included in Message A transmitted from terminal 200 (ST107). When base station 100 detects a RACH preamble, it identifies the TBS of the data portion of Message A transmitted from terminal 200 from the RACH preamble resource corresponding to the detected RACH preamble, based on the association between the TBS and the RACH preamble resource group (see, for example, FIG. 7).

[0095] Base station 100 uses the identified TBS to demodulate and decode the data portion of Message A corresponding to the detected RACH preamble (ST108).

[0096] After receiving processing of Message A (for example, detecting the RACH preamble, and demodulating and decoding the data portion), base station 100 generates Message B (ST109) and transmits generated Message B to terminal 200 (ST110).

[0097] Note that, in the present embodiment, a case has been described in which the TBS of the data portion of Message A is used as an example of the transmission parameter of Message A, but the transmission parameter of Message A is not limited to the TBS and may be another parameter. For example, resource information of the data portion of Message A (e.g., at least one of the resource location and the resource amount) may be associated with a group of RACH preamble resource candidates for Message A. In this case, when base station 100 detects a RACH preamble, it can identify the resource location or resource amount used by terminal 200 to transmit the data portion of Message A from the detected RACH preamble resource. Furthermore, base station 100 may calculate the TBS used for the data portion using, for example, the identified resource location and resource amount of the data portion, and demodulate and decode the data portion of Message A corresponding to the detected RACH preamble.

[0098] As described above, in the present embodiment, terminal 200 dynamically determines parameters (transmission parameters) related to transmission of the data portion of Message A (in other words, a random access signal) including a RACH preamble and a data portion. This allows terminal 200 to appropriately select transmission parameters (for example, TBS, resource position, or resource amount) to be used in the data portion of Message A according to the generated transmission packet.

[0099] Furthermore, in the present embodiment, terminal 200 notifies base station 100 of the determined transmission parameters by using Message A. For example, in the present embodiment, terminal 200 transmits a RACH preamble using a RACH preamble resource in a RACH preamble resource candidate group that is associated with the dynamically determined transmission parameters based on the association between candidates for the transmission parameters (for example, TBS) and a RACH preamble resource candidate group.

[0100] As described above, in the present embodiment, the TBS of the data portion of Message A is implicitly notified from terminal 200 to base station 100 by the RACH preamble resource used to transmit the RACH preamble in Message A. For example, base station 100 can implicitly identify the TBS used for the data portion of Message A based on the RACH preamble resource used to transmit the detected RACH preamble.

[0101] This increases the likelihood that base station 100 can correctly demodulate and decode Message A in accordance with the TBS dynamically determined in terminal 200. Furthermore, there is no need for terminal 200 to explicitly notify base station 100 of the transmission parameters of Message A, thereby reducing overhead.

[0102] Therefore, according to this embodiment, it is possible to improve the efficiency of uplink transmission in, for example, a two-step random access procedure.

[0103] [Message A] Next, Message A in the two-step random access procedure will be explained.

[0104] In Message A, the RACH preamble and the data portion may be configured by, for example, time division multiplexing (TDM). Note that the multiplexing configuration of the RACH preamble and the data portion of Message A is not limited to TDM, and may be frequency division multiplexing (FDM) or code division multiplexing (CDM).

[0105] Furthermore, the data transmitted by terminal 200 in the data portion of Message A may include UP data in addition to C-plane data such as an RRC connection request or a scheduling request. Furthermore, the data transmitted by terminal 200 in the data portion of Message A may include C-plane data but not UP data.

[0106] For example, C-plane data includes an RRC connection request (RRCSetupRequest: 44 bits) at the time of initial access, a request when returning from the RRC_IACTIVE state to the RRC_CONNECTED state (RRCResumeRequest: 48 bits), an RRC reconnection request (RRCReestablishmentRequest: 44 bits or RRCReestablishmentRequest1: 64 bits), a scheduling request when uplink data occurs (Short BSR MAC CE + C-RNTI MAC CE: 24 bits, or Long BSR MAC CE + C-RNTI MAC CE: 32 bits or more), and an on-demand SI request (RRCSystemInforRequest), etc. Note that the number of bits of the above-mentioned C-Plane data is the number of bits of each C-plane data in Release 15 NR, and the number of bits is not limited to this.

[0107] The C-plane data may also include, for example, a UE-ID. The UE-ID included in Message A may be an SAE Temporary Mobile Subscriber Identity (S-TMSI) at the time of the RRC connection request, a random bit sequence, a C-RNTI in the RRC_CONNECTED state, or a ResumeID in the RRC_IACTIVE state.

[0108] Furthermore, the UE-ID may be transmitted together with other C-plane information in the data portion of Message A, or may be transmitted in UCI. When the UE-ID is transmitted in UCI, the UE-ID may be included in UCI including information on the TBS in the third to fifth embodiments described later.

[0109] [Message B] Next, Message B in the two-step random access procedure will be explained.

[0110] Message B includes, for example, a MAC PDU (Medium Access Control layer Protocol Data Unit) including a RACH response (RAR), a MAC PDU including a message (for example, Contention resolution MAC CE) including a UE-ID for identifying terminal 200, etc. In addition to the above MAC PDU, Message B may also include a MAC PDU including an RRC signal for RRC connection, RRC recovery, or RRC reconnection.

[0111] Furthermore, the MAC PDU including the RAR may include information on the uplink transmission timing by terminal 200, TC-RNTI, or information on resources used by terminal 200 on the uplink.

[0112] When terminal 200 in which the random access procedure has succeeded transmits Message B including a MAC PDU containing an RRC signal, the information on resources used in the uplink can be used to transmit messages for completing RRC connection, RRC recovery, and RRC reconnection to base station 100. Furthermore, terminal 200 that falls back to the four-step RACH procedure can use the information on resources used in the uplink to transmit Message 3.

[0113] In the four-step random access procedure, information on resources used in the uplink for transmitting Message 3 and information for receiving Message 4 (for example, TC-RNTI) need to be included in Message 2 (RAR). In contrast, in the two-step random access procedure, these operations are not necessarily required, and therefore information on resources used in the uplink and TC-RNTI do not need to be included in Message B (for example, RAR). In this case, whether or not Message B (RAR) includes this information (in other words, the format of the RAR) may be identified by terminal 200 depending on whether or not Message B includes a MAC PDU including an RRC signal, or may be identified by terminal 200 using one bit of the MAC header.

[0114] Terminal 200 receives Message B based on the UE-ID transmitted in Message A. At this time, a downlink control channel (for example, PDCCH: Physical Downlink Control Channel) for scheduling Message B may be scrambled by an RA-RNTI common to all terminals or a terminal-specific C-RNTI.

[0115] For example, when terminal 200 is in the RRC_IDLE state or the RRC_INACTIVE state, terminal 200 receives a PDCCH scrambled with an RA-RNTI that is common to all terminals. At this time, the RAR in Message B includes at least information on uplink transmission timing. If Message B does not include a MAC PDU that includes an RRC signal, the RAR includes a TC-RNTI. On the other hand, if Message B includes a MAC PDU that includes an RRC signal, the TC-RNTI is not necessary. Furthermore, Message B includes a MAC PDU that includes a message (for example, a Contention resolution MAC CE) that includes a UE-ID for identifying terminal 200.

[0116] When terminal 200 is in the RRC_CONNECTED state, terminal 200 receives a PDCCH scrambled with a terminal-specific C-RNTI. At this time, the RAR in Message B includes at least information on uplink transmission timing and information on resources used in the uplink.

[0117] If Message B includes a MAC PDU containing an RRC signal, the RRC signal consists of a relatively large amount of data. Therefore, applying HARQ (Hybrid Automatic Repeat Request) to the transmission of Message B can improve the utilization efficiency of downlink resources.

[0118] On the other hand, if HARQ is not applied to Message B, or if HARQ is applied but the configuration of Message B is not optimized for HARQ, Message B may be transmitted by groupcast. Configuration examples of Message B in this case are shown in Figures 8 and 9. Figure 8 shows an example where Message B does not include a MAC PDU including an RRC signal, and Figure 9 shows an example where Message B includes a MAC PDU including an RRC signal.

[0119] [2-Step Random Access Procedure] Next, an example of the operation after transmitting Message A in the 2-step Random Access Procedure will be described.

[0120] Examples of operations 1 and 2 will be described below.

[0121] [Operation Example 1] FIG. 10 shows an example of the 2-step Random Access Procedure in Operation Example 1.

[0122] <Transmission of Message A> The terminal 200 (UE#A, UE#B, and UE#C in FIG. 10) transmits Message A as described above. Message A includes a RACH preamble and a data part (or, UCI + data part). Also, the data part or UCI includes a UE-ID for identifying the terminal 200. Further, the terminal 200 operates a Msg.B reception window (which may also be referred to as a RAR reception window) from the transmission timing of the RACH preamble.

[0123] <Transmission of Message B> When the base station 100 (gNB in FIG. 10) detects and correctly decodes Message A, it transmits Message B. Message B includes, for example, a RACH response (referred to as RAR or MAC RAR) and a message (e.g., MAC CE) including a UE-ID for identifying the terminal 200.

[0124] On the other hand, if base station 100 is unable to detect Message A (for example, if it is unable to detect the RACH preamble), or if it is unable to correctly decode Message A (for example, if it detects the RACH preamble but is unable to correctly decode the data portion (for example, PUSCH)), it does not include in Message B information addressed to terminal 200 that transmitted Message A.

[0125] 10, for example, base station 100 (gNB) detects and correctly decodes Message A transmitted from UE#A (Preamble: O, PUSCH: O). Then, base station 100 includes in Message B the RACH response to UE#A and the UE-ID of UE#A.

[0126] On the other hand, in FIG. 10, the base station 100 (gNB) detects Message A transmitted from UE#B but is unable to correctly decode Message A (Preamble: O, PUSCH: ×). Also in FIG. 10, the base station 100 (gNB) is unable to detect Message A transmitted from UE#C (Preamble: ×, PUSCH: ×). Therefore, the base station 100 does not include the RACH responses and UE-IDs for UE#B and UE#C in Message B.

[0127] If terminal 200 that sent Message A does not receive Message B containing information addressed to that terminal 200 within the Msg. B reception window period (e.g., corresponding to UE#B and UE#C in Figure 10), it resends Message A.

[0128] On the other hand, terminal 200 that sent Message A receives Message B containing information addressed to terminal 200 within the Msg.B reception window, and if the UE-ID contained in Message B matches the UE-ID sent in Message A (e.g., corresponding to UE#A in FIG. 10), it determines that the RACH procedure was successful.

[0129] [Operation Example 2] FIG. 11 shows an example of a two-step Random access procedure in Operation Example 2.

[0130] <Transmission of Message A> The terminal 200 (UE#A, UE#B, and UE#C in FIG. 11) transmits Message A as described above. Message A includes a RACH preamble and a data part (or UCI + data part). Also, the data part or UCI includes a UE-ID for identifying the terminal 200. Further, the terminal 200 operates the Msg.B reception window from the transmission timing of the RACH preamble.

[0131] [[ID=1​​​​​Base station 100 also transmits Message B when it detects the RACH preamble of Message A but is unable to correctly decode the data portion. At this time, Message B includes a RACH response (referred to as an RAR or MAC RAR). Note that RAR includes a request for retransmission of the data portion to terminal 200 that transmitted the corresponding RACH preamble, and information regarding resources to be used in the uplink. However, if base station 100 detects the RACH preamble but is unable to correctly decode the data portion, it is unable to identify terminal 200 that transmitted the RACH preamble at this point. Therefore, Message B does not include a message including a UE-ID for identifying corresponding terminal 200. Terminal 200 that detected the RACH preamble but was unable to correctly decode the data portion falls back to, for example, a four-step RACH procedure.

[0133] 11, base station 100 detects Message A transmitted from UE#B but cannot correctly decode Message A (Preamble: O, PUSCH: ×). Therefore, base station 100 includes a RACH response for UE#B in Message B, but does not include a UE-ID for UE#B in Message B.

[0134] Furthermore, if base station 100 is unable to detect Message A (for example, if it is unable to detect a RACH preamble), it does not include information addressed to terminal 200 that transmitted Message A in Message B. For example, in FIG. 10, base station 100 is unable to detect Message A transmitted from UE#C (Preamble: ×, PUSCH: ×). Therefore, base station 100 does not include a RACH response to UE#C and the UE-ID of UE#C in Message B.

[0135] Terminal 200 that transmitted Message A retransmits Message A if it does not receive Message B including information addressed to that terminal 200 within the Msg. B reception window period (for example, corresponding to UE#C in FIG. 11).

[0136] On the other hand, if terminal 200 that transmitted Message A receives Message B including information addressed to terminal 200 within the Msg. B reception window, but the UE-ID included in Message B does not match the UE-ID transmitted in Message A (e.g., corresponding to UE#B in FIG. 11), it performs uplink transmission corresponding to Message 3 of the four-step RACH procedure in accordance with the information included in the RAR in the corresponding Message B. In other words, UE#B falls back to the four-step Random access procedure.

[0137] Furthermore, terminal 200 that sent Message A receives Message B containing information addressed to terminal 200 within the Msg.B reception window, and if the UE-ID contained in Message B matches the UE-ID sent in Message A (e.g., corresponding to UE#A in FIG. 11), it determines that the RACH procedure was successful.

[0138] The above describes an example of the operation after sending Message A in the two-step random access procedure.

[0139] In Operation Example 1 and Operation Example 2, the period set in the Msg.B reception window may be varied depending on, for example, the type of service or traffic. For example, the period set in the Msg.B reception window may be longer for eMBB or mMTC, which have less strict delay requirements, and shorter for URLLC, which has strict delay requirements.

[0140] Furthermore, in Operation Example 1 and Operation Example 2, Message B may include information (Back-off) that specifies a waiting time for retransmission. For example, even if Message B does not include information addressed to terminal 200 (for example, RAR or UE-ID), terminal 200 can control the retransmission of Message A based on information that specifies a waiting time for retransmission. In this case, for example, terminal 200 with strict delay requirements (for example, URLLC terminal) may start retransmission of Message A by setting the specified back-off to a shorter value (or to 0) rather than using the back-off specified by base station 100.

[0141] (Embodiment 2) A base station and a terminal according to this embodiment have the same basic configuration as base station 100 and terminal 200 according to the first embodiment, and therefore will be described with reference to FIGS.

[0142] In the first embodiment, a case has been described in which a TBS (in other words, one transmission parameter) of the data portion of Message A is associated with a group of RACH preamble resource candidates of Message A. In contrast, in the present embodiment, a case will be described in which a plurality of transmission parameters of the data portion of Message A are associated with a group of RACH preamble resources of Message A.

[0143] The multiple transmission parameters in the data portion of Message A may include, for example, a TBS and resource information (for example, at least one of a resource location and a resource amount). Note that the transmission parameters are not limited to the TBS and resource information, and may be other parameters (an example of which will be described later).

[0144] For example, base station 100 uses higher layer signaling to notify terminal 200 of multiple combinations of associations between TBSs and resource information in the data portion of Message A and RACH preamble resource candidates (e.g., corresponding to ST101 in FIG. 6). The higher layer signal may be, for example, cell- or group-specific broadcast information (e.g., SIB), or a terminal-specific RRC signal.

[0145] Terminal 200 selects a TBS for the data portion of Message A from among multiple TBSs set by base station 100. Terminal 200 may select a TBS for the data portion of Message A, for example, based on the amount of data of the data portion to actually be transmitted (for example, a Buffer value). In this case, the Buffer value used as a criterion for TBS selection may be, for example, the amount of UP data, or the total amount of data of C-plane data and UP data such as an RRC connection request or a scheduling request.

[0146] Furthermore, in the method of selecting a TBS based on the buffer value, a TBS that reduces the amount of zero padding may be selected, thereby improving the efficiency of resource usage in the data portion of Message A.

[0147] Terminal 200 also selects a RACH preamble resource to actually use from a group of RACH preamble resource candidates associated with the selected TBS. Terminal 200 also identifies resource information (e.g., at least one of resource location and resource amount) in the data portion of Message A associated with the selected TBS.

[0148] FIG. 12 shows an example of association between resource information of the TBS and data portion (for example, resource locations and resource amounts of time resources and frequency resources) and a group of RACH preamble resource candidates.

[0149] FIG. 12 also shows, as an example, associations relating to a method of selecting a TBS based on the amount of data (for example, a buffer value) in the data portion of Message A in terminal 200.

[0150] 12, TBS=X1 is associated with RACH preamble resource candidate group Z1 and data portion resource information Resource 1, TBS=X2 is associated with RACH preamble resource candidate group Z2 and data portion resource information Resource 2, and TBS=X3 is associated with RACH preamble resource candidate group Z3 and data portion resource information Resource 3. Note that the number of TBS and resource information candidates associated with the RACH preamble resource group is not limited to three, and may be two or four or more.

[0151] For example, in FIG. 12, if the Buffer value is Y1 or less, terminal 200 selects TBS=X1 (and RACH preamble resource candidate group Z1, Resource 1), if the Buffer value is Y2 or less, terminal 200 selects TBS=X2 (and RACH preamble resource candidate group Z2, Resource 2), and if the Buffer value is Y3 or less, terminal 200 selects TBS=X3 (and RACH preamble resource candidate group Z3, Resource 3).

[0152] Terminal 200 generates Message A including a signal of the data portion of Message A (for example, at least one of C-Plane data and UP data) generated using the selected TBS and resource information, and a RACH preamble generated using the selected RACH preamble resource. Terminal 200 transmits the generated Message A to base station 100.

[0153] The RACH preamble and data portion of Message A may be configured using, for example, TDM, FDM, or CDM. Furthermore, the data transmitted by terminal 200 in the data portion of Message A may include UP data in addition to C-plane data such as an RRC connection request or a scheduling request. Alternatively, the data transmitted by terminal 200 in the data portion of Message A may include, for example, C-plane data but not UP data.

[0154] When base station 100 detects a RACH preamble included in Message A transmitted from terminal 200, it identifies the TBS and resource information of the data portion of Message A transmitted from terminal 200 from the RACH preamble resource corresponding to the detected RACH preamble, based on the correspondence between the transmission parameters of Message A (e.g., TBS and resource information) and the RACH preamble resource group.

[0155] Base station 100 demodulates and decodes the data portion of Message A corresponding to the detected RACH preamble using the identified TBS and resource information. Then, for example, after receiving Message A, base station 100 transmits Message B to terminal 200.

[0156] As described above, in the present embodiment, terminal 200 dynamically determines parameters (transmission parameters) related to transmission of the data portion of Message A, which includes a RACH preamble and a data portion. This allows terminal 200 to appropriately select transmission parameters (for example, TBS and resource information) to be used in the data portion of Message A according to the generated transmission packet.

[0157] Also, in the present embodiment, similarly to the first embodiment, terminal 200 notifies base station 100 of the determined transmission parameters by using Message A. For example, in the present embodiment, terminal 200 transmits a RACH preamble using a RACH preamble resource in a group of RACH preamble resource candidates that is associated with the dynamically determined transmission parameters based on the association between candidates for the transmission parameters (for example, TBS and resource information) and a group of RACH preamble resource candidates.

[0158] As a result, for example, base station 100 can implicitly identify the TBS and resource information used for the data portion of Message A based on the RACH preamble resource used to transmit the detected RACH preamble. This increases the likelihood that base station 100 can correctly demodulate and decode Message A according to transmission parameters (e.g., TBS and resource information) dynamically determined in terminal 200. Furthermore, because there is no need for terminal 200 to explicitly notify base station 100 of the transmission parameters of Message A, overhead can be reduced.

[0159] Furthermore, in this embodiment, base station 100 can set correspondence between a plurality of transmission parameters of Message A (for example, TBS and resource information of the data portion) and a group of RACH preamble resource candidates. As a result, in the case of a contention-based RACH, for example, base station 100 can easily control the collision probability of RACH preamble resources or resources of the data portion by setting the above correspondence according to, for example, the bandwidth available to the system or the traffic situation in the cell.

[0160] In this embodiment, the association between the RACH preamble resource candidate group and the transmission parameters (e.g., TBS and resource information) may be such that all information of the transmission parameters is associated with the RACH preamble resource candidate group, or such that only part of the information is associated with the RACH preamble resource group.

[0161] [Variation 1] In Embodiment 2, the transmission parameters associated with the RACH preamble resource candidate group are not limited to the TBS and the resource information of the data part. Other parameters related to the transmission of Message A may be associated with the RACH preamble resource candidate group.

[0162] Hereinafter, examples of other parameters associated with the RACH preamble resource candidate group in Variation 1 will be described.

[0163] [Association with the MCS of the data part of Message A] Generally, the selectable RACH preamble resource candidates are different when the path loss between the base station 100 and the terminal 200 is greater than or equal to a threshold and when it is less than the threshold.

[0164] For example, the terminal 200 measures the path loss between the base station 100 and the terminal 200 using a downlink signal or a downlink channel. Then, the terminal 200 may select the RACH preamble resource to be actually used from the RACH preamble resource candidate group associated with the measured path loss.

[0165] Also, the terminal 200 selects the MCS of the data part of Message A associated with the selected RACH preamble resource candidate group (in other words, the path loss). For example, when the path loss is greater than or equal to the threshold, the terminal 200 uses a low MCS for the data part of Message A. On the other hand, when the path loss is less than the threshold, the terminal 200 uses a high MCS for the data part of Message A. Thereby, the terminal 200 can appropriately control the transmission quality of Message A according to the propagation path situation and improve the transmission efficiency of Message A.

[0166] Furthermore, the group of RACH preamble resource candidates associated with the above-described Path loss and MCS may be respectively associated with subgroups associated with TBS or resource information of the data part (e.g., at least one of resource position and resource amount).

[0167] For example, FIG. 13 shows an example of sub-grouping the group of RACH preamble resource candidates associated with Path loss and MCS by associating TBS with the group of RACH preamble resource candidates (including also the selection of TBS based on the Buffer value of the terminal 200). In FIG. 13, the RACH preamble resource group is grouped into a group when the Path loss is greater than the threshold Th (MCS A1) and a group when the Path loss is less than or equal to the threshold Th (MCS A2). Each group shown in FIG. 13 includes a combination of TBS = X1 and the RACH preamble resource candidate group Z1, and a combination of TBS = X2 and the RACH preamble resource candidate group Z2. Note that FIG. 13 is an example, and for example, resource information of the data part may be included.

[0168] <Association with the transmission power of Message A> For example, the group of RACH preamble resource candidates and the transmission power of Message A may be associated.

[0169] For example, the transmission power of Message A may be varied according to the group of RACH preamble resources associated with TBS. For example, when selecting a RACH preamble from the group of RACH preamble resources associated with TBS = X1, the terminal 200 sets P1 as the transmission power of Message A. Also, when selecting a RACH preamble from the group of RACH preamble resources associated with TBS = X2, the terminal 200 sets P2 as the transmission power of Message A.

[0170] Here, the higher the TBS, the higher the transmission power is set. For example, when X1 < X2, the relationship is P1 < P2. The larger the TBS for transmission, the lower the utilization efficiency of the uplink resources will be if retransmission occurs. In contrast, by associating the above-mentioned RACH preamble resource group with the transmission power, for example, for a transmission with a large TBS, a high transmission power can be set, so that frequent retransmission can be prevented and the transmission efficiency of Message A can be improved.

[0171] Note that the parameter related to the transmission power associated with the RACH preamble resource candidate group is not limited to the transmission power. For example, it may be the power increase amount for each retransmission of Message A.

[0172] <Association with the Rank of the Data Portion of Message A> For example, the RACH preamble resource candidate group and the number of transmission ranks of the data portion of Message A may be associated.

[0173] For example, the number of transmission ranks of the data portion of Message A may be varied according to the RACH preamble resource group associated with the TBS. Thereby, for example, MIMO (Multi-input Multi-output) spatial multiplexing transmission can be applied to the transmission of Message A, so that the transmission efficiency of Message A can be improved.

[0174] [Variation 2] The TBS associated with the RACH preamble resource candidate group in Embodiment 2 may be the maximum TBS that the terminal 200 can transmit (or set).

[0175] Also, for example, as shown in FIG. 14, a plurality of TBSs (for example, allowable TBS) less than or equal to the maximum TBS may be associated with the RACH preamble resource candidate group. In this case, the terminal 200 may select the TBS based on, for example, the actual uplink data amount to be transmitted (for example, Buffer value).

[0176] The buffer value used for TBS selection may be the amount of UP data, or the sum of the amount of C-plane data such as an RRC connection request or a scheduling request and the amount of UP data. Alternatively, a TBS may be selected based on the buffer value, such that the TBS with the smallest amount of zero padding is selected. This allows for efficient configuration of RACH resources while more flexibly supporting transmission of various amounts of UP data.

[0177] Furthermore, when base station 100 detects a RACH preamble, it identifies the largest TBS that terminal 200 may use to transmit Message A, or multiple TBS candidates smaller than the largest TBS, from the RACH preamble resources corresponding to the detected RACH preamble. For example, base station 100 performs blind decoding on the identified multiple TBS candidates, and demodulates and decodes the data portion of Message A.

[0178] [Variation 3] The number of RACH preamble resources included in the RACH preamble resource candidate groups in the second embodiment may differ for each RACH preamble resource candidate group.

[0179] For example, as shown in FIG. 15, the number of RACH preamble resources included in a RACH preamble resource candidate group Z1 associated with TBS=X1 may be set to N1, the number of RACH preamble resources included in a RACH preamble resource candidate group Z2 associated with TBS=X2 may be set to N2, and the number of RACH preamble resources included in a RACH preamble resource candidate group Z3 associated with TBS=X3 may be set to N3.

[0180] In FIG. 15, X1 < X2 < X3 and N1 < N2 < N3. That is, the larger the TBS, the larger the number of RACH preamble resources included in the RACH preamble resource candidate group is set. The larger the number of RACH preamble resources included in the RACH preamble candidate group, the lower the collision probability of the RACH preamble can be reduced. For a transmission with a larger TBS, if retransmission occurs, the utilization efficiency of the uplink resource will decrease. In contrast, in FIG. 15, for example, for a transmission with a larger TBS, a larger number of RACH preamble resources are set, and frequent retransmission can be prevented, so the transmission efficiency of Message A can be improved.

[0181] Depending on the traffic situation of the terminals included in the cell, there may be few terminals that transmit a large amount of uplink data and many terminals that transmit a small amount of uplink data. Therefore, the smaller the TBS, the smaller the number of RACH preamble resources included in the RACH preamble resource candidate group may be set.

[0182] [Variation 4] The synchronization signal in NR is composed of, for example, two signals, PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization) (see, for example, Non-Patent Document 1). In particular, in a high-frequency band of 6 GHz or higher, in order to ensure the communication distance and area between the base station and the terminal, for example, it is conceivable to apply transmission beamforming on the base station side.

[0183] In addition, NR defines a synchronization signal and a broadcast channel (PBCH: Physical Broadcast Channel) as a single unit (e.g., called an SS / PBCH block). One SS / PBCH block is transmitted using a transmission beam in the same direction, and a configuration in which the beam is sequentially switched (beam sweeping) is supported. However, for low frequency bands, etc., a configuration in which one SS / PBCH block is transmitted using a single beam pattern without applying beam sweeping is also possible.

[0184] When beamforming is applied to an SS / PBCH block, the base station applies equivalent receive beamforming to receive the RACH from the terminal that received that SS / PBCH block. Therefore, the terminal transmits the RACH using the RACH preamble resource associated with the detected SS / PBCH block (see, for example, Non-Patent Document 6). Also, measurements using a channel state information reference signal (CSI-RS) for channel state estimation may be configured in the terminal, and the CSI-RS may be associated with the RACH preamble resource (see, for example, Non-Patent Document 6).

[0185] In variation 4, terminal 200 measures reception quality (e.g., referred to as SS-RSRP (Reference Signal Received Power) or CSI-RSRP) using, for example, an SS / PBCH block or a CSI-RS. If there are one or more SS / PBCH blocks or CSI-RS for which the SS-RSRP or CSI-RSRP is equal to or greater than a threshold, terminal 200 selects one SS / PBCH block or CSI-RS from among them and selects a RACH preamble from a group of RACH preamble resource candidates associated with that SS / PBCH block or CSI-RS. Note that if there is no SS / PBCH block or CSI-RS for which the SS-RSRP or CSI-RSRP is equal to or greater than the threshold, terminal 200 may select an SS / PBCH or CSI-RS corresponding to any of the SS-RSRP or CSI-RSRP.

[0186] At this time, terminal 200 may select an SS / PBCH block or CSI-RS according to the TBS (in other words, the transmission parameters of the data portion of Message A). For example, terminal 200 may vary the threshold of SS-RSRP or CSI-RSRP according to the TBS. For example, terminal 200 sets a higher threshold of SS-RSRP or CSI-RSRP as the TBS increases. In this case, terminal 200 can select a beam pattern of higher quality for transmissions with a large TBS. Therefore, frequent retransmissions can be prevented for transmissions with a large TBS, which would reduce the efficiency of uplink resource utilization if retransmissions occur, thereby improving the transmission efficiency of Message A.

[0187] (Embodiment 3) A base station and a terminal according to this embodiment have the same basic configuration as base station 100 and terminal 200 according to the first embodiment, and therefore will be described with reference to FIGS.

[0188] In this embodiment, terminal 200 includes information about the TBS in the data portion of Message A in UCI and notifies base station 100 during the two-step random access procedure.

[0189] FIG. 16 shows an example of the flow of processing in base station 100 and terminal 200 according to this embodiment.

[0190] In this embodiment, base station 100 may notify terminal 200 of a plurality of combinations of associations between transmission parameters (e.g., TBS or resource information) of the data portion of Message A and UCI bit fields (see, for example, FIG. 17 described later), for example, by using higher layer signaling. The higher layer signal is, for example, cell- or group-specific broadcast information (e.g., SIB) or a terminal-specific RRC signal.

[0191] When a transmission packet (in other words, an uplink signal) is generated, terminal 200 determines a TBS for the data portion of Message A (ST201). For example, multiple TBSs may be predefined in the standard as TBSs that terminal 200 can select from, or base station 100 may set a TBS using a higher layer signal (for example, an SIB or a terminal-specific RRC signal). For example, terminal 200 dynamically determines a TBS for the data portion of Message A from among the defined or set TBSs.

[0192] Terminal 200 determines a RACH preamble to transmit (ST202). For example, terminal 200 selects a group of RACH preamble resource candidates to be actually used from a plurality of RACH preamble resource candidate groups, and selects a RACH preamble to be used for Message A from the selected group of RACH preamble resource candidates. Note that the selection of the group of RACH preamble resource candidates may be based on, for example, a path loss between base station 100 and terminal 200, or on an SS / PBCH block or CSI-RS, and is not limited to these selection methods.

[0193] Terminal 200 determines the value of UCI (for example, index) to be included in Message A (ST203). For example, terminal 200 generates UCI including an index associated with information related to the TBS of the data portion of Message A.

[0194] Figure 17 shows an example of the correspondence between TBSs and UCI bit fields. In Figure 17, for example, when TBS=X1 is selected, index 1 is set in the UCI bit field, when TBS=X2 is selected, index 2 is set in the UCI bit field, and when TBS=X3 is selected, index 3 is set in the UCI bit field. Note that the number of TBSs to be set is not limited to three, and may be, for example, two or four or more.

[0195] 16, terminal 200 generates Message A (ST204). For example, terminal 200 generates the data portion of Message A using the selected TBS. Furthermore, terminal 200 multiplexes UCI including an index corresponding to information related to the TBS into the data portion of Message A. Furthermore, for example, terminal 200 generates a RACH preamble for Message A using the selected RACH preamble resource.

[0196] Terminal 200 transmits the generated Message A to base station 100 (ST205).

[0197] Furthermore, the data transmitted by terminal 200 in the data portion of Message A may include UP data in addition to C-plane data such as an RRC connection request or a scheduling request. Furthermore, the data transmitted by terminal 200 in the data portion of Message A may include C-plane data but not UP data.

[0198] Base station 100 identifies the TBS used by terminal 200 to transmit Message A by demodulating and decoding the UCI included in Message A transmitted from terminal 200 (ST206).

[0199] Base station 100 demodulates and decodes the data portion of Message A using the identified TBS (ST207).

[0200] After receiving and processing Message A, base station 100 generates Message B (ST208) and transmits generated Message B to terminal 200 (ST209).

[0201] As described above, in the present embodiment, terminal 200 dynamically determines parameters (transmission parameters) related to transmission of the data portion of Message A (in other words, a random access signal) including a RACH preamble and a data portion. This allows terminal 200 to appropriately select transmission parameters (for example, TBS, resource position, or resource amount) to be used in the data portion of Message A according to the generated transmission packet.

[0202] Also, in this embodiment, terminal 200 uses Message A to notify base station 100 of the determined transmission parameters. For example, in this embodiment, terminal 200 transmits Message A including UCI indicating information related to transmission parameters (for example, TBS) to base station 100. That is, in this embodiment, the TBS of the data portion of Message A is explicitly notified from terminal 200 to base station 100 by the UCI included in Message A. For example, base station 100 can identify the TBS used for the data portion of Message A based on the received UCI.

[0203] This increases the likelihood that base station 100 can correctly demodulate and decode Message A in accordance with the TBS dynamically determined in terminal 200.

[0204] Furthermore, in the present embodiment, unlike in Embodiments 1 and 2, there is no need for multiple RACH preamble resource candidate groups associated with the transmission parameters of the data portion of Message A. In other words, in the present embodiment, for example, one RACH preamble resource candidate group is sufficient for terminal 200. Therefore, according to the present embodiment, RACH preamble resources can be efficiently configured.

[0205] Although the present embodiment has been described with reference to a case where the TBS of the data portion of Message A is used as an example of the transmission parameter of Message A, the transmission parameter of Message A is not limited to the TBS and may be other parameters. For example, resource information of the data portion of Message A (e.g., at least one of the resource position and the resource amount) may be associated with a group of RACH preamble resource candidates of Message A.

[0206] (Fourth embodiment) A base station and a terminal according to this embodiment have the same basic configuration as base station 100 and terminal 200 according to the first embodiment, and therefore will be described with reference to FIGS.

[0207] In this embodiment, terminal 200 includes information about the TBS in the data portion of Message A in UCI, as in the third embodiment, and notifies base station 100 of this information during the two-step random access procedure.

[0208] Furthermore, in this embodiment, the transmission parameters included in the UCI may include resource information of the data portion of Message A (for example, at least one of the resource location and the resource amount) in addition to the TBS of the data portion of Message A.

[0209] Furthermore, in this embodiment, resource information (for example, at least one of resource location and resource amount) of UCI transmitted in Message A may be associated with the RACH preamble resource of Message A (or a group of RACH preamble resource candidates).

[0210] For example, base station 100 uses higher layer signaling to notify terminal 200 of a plurality of combinations of associations between TBSs in the data portion of Message A and UCI bit fields (e.g., indexes) and associations between UCI resource information and RACH preamble resources (or RACH preamble resource candidates). The higher layer signaling is, for example, cell- or group-specific broadcast information (e.g., SIBs) or a terminal-specific RRC signal.

[0211] Terminal 200 dynamically determines the TBS of the data portion of Message A from among a plurality of TBSs (TBS candidates) set by base station 100, for example.

[0212] Terminal 200 may select a TBS for the data portion of Message A based on, for example, the amount of UP data to be actually transmitted (e.g., a buffer value). Note that the buffer value used for TBS selection may be, for example, the amount of UP data, or the total amount of C-plane data and UP data, such as an RRC connection request or a scheduling request. Furthermore, in a method of selecting a TBS based on the buffer value, a TBS with a smaller amount of zero padding may be selected. This can improve the efficiency of resource usage for the data portion of Message A.

[0213] Also, similar to the third embodiment, terminal 200 generates a UCI indicating information related to the TBS of the data portion of Message A. For example, terminal 200 generates a UCI including an index associated with information related to the TBS of the data portion of Message A.

[0214] 18 shows an example of the correspondence between TBSs and UCI bit fields, and also shows the correspondence regarding a method of selecting a TBS based on the Buffer value of the terminal 200.

[0215] 18, for example, when TBS=X1 is selected, index 1 is set in the UCI bit field, when TBS=X2 is selected, index 2 is set in the UCI bit field, and when TBS=X3 is selected, index 3 is set in the UCI bit field. Note that the number of TBSs to be set is not limited to three, and may be, for example, two or four or more.

[0216] For example, in FIG. 18, if the buffer value is Y1 or less, terminal 200 selects TBS=X1 (and index 1 of the UCI bit field); if the buffer value is Y2 or less, terminal 200 selects TBS=X2 (and index 2 of the UCI bit field); and if the buffer value is Y3 or less, terminal 200 selects TBS=X3 (and index 3 of the UCI bit field).

[0217] Terminal 200 also selects a RACH preamble resource to actually use from, for example, a group of RACH preamble resource candidates. Terminal 200 also identifies resource information of the UCI of Message A (for example, at least one of the resource location and the resource amount) from the selected RACH preamble resource, for example, based on the association between resource information of the UCI and the RACH preamble resource.

[0218] Terminal 200 generates the data portion of Message A using, for example, the selected TBS. Terminal 200 also multiplexes UCI including an index corresponding to information related to the TBS into the data portion of Message A. The UCI is mapped to the data portion of Message A based on, for example, the resource position and resource amount associated with the RACH preamble resource (or a group of RACH preamble resource candidates) of Message A. Terminal 200 also generates the RACH preamble of Message A using, for example, the selected RACH preamble resource.

[0219] The RACH preamble resource of Message A and the data portion of Message A may be configured using, for example, TDM, FDM, or CDM. Furthermore, the data transmitted by terminal 200 in the data portion of Message A may include, for example, UP data in addition to C-plane data such as an RRC connection request or a scheduling request. Alternatively, the data transmitted by terminal 200 in the data portion of Message A may not include, for example, UP data, but may include C-plane data such as an RRC connection request or a scheduling request.

[0220] The terminal 200 transmits the generated Message A to the base station 100.

[0221] When base station 100 detects a RACH preamble, it identifies resource information used by terminal 200 to transmit UCI of Message A, from the RACH preamble resource corresponding to the detected RACH preamble. Furthermore, base station 100 demodulates and decodes UCI using the identified resource information of UCI, thereby being able to identify resource information of the TBS and data portion used by terminal 200 to transmit Message A.

[0222] Base station 100 demodulates and decodes the data portion of Message A corresponding to the detected RACH preamble using the identified TBS and resource information of the data portion. After receiving Message A, base station 100 generates Message B and transmits the generated Message B to terminal 200.

[0223] As described above, in the present embodiment, terminal 200 dynamically determines parameters (transmission parameters) related to transmission of the data portion of Message A, which includes a RACH preamble and a data portion. This allows terminal 200 to appropriately select transmission parameters (for example, TBS and resource information) to be used in the data portion of Message A according to the generated transmission packet.

[0224] Furthermore, in the present embodiment, terminal 200 transmits Message A including UCI indicating information related to transmission parameters (for example, TBS and resource information) to base station 100, as in the third embodiment. That is, in the present embodiment, the TBS and resource information of the data portion of Message A are explicitly notified from terminal 200 to base station 100 by the UCI included in Message A. For example, base station 100 can identify the TBS and resource information used in the data portion of Message A based on the received UCI.

[0225] This increases the likelihood that base station 100 can correctly demodulate and decode Message A in accordance with the TBS and resource information dynamically determined in terminal 200.

[0226] Furthermore, in the present embodiment, unlike in Embodiments 1 and 2, there is no need for multiple RACH preamble resource candidate groups associated with the transmission parameters of the data portion of Message A. In other words, in the present embodiment, for example, one RACH preamble resource candidate group is sufficient for terminal 200. Therefore, according to the present embodiment, RACH preamble resources can be efficiently configured.

[0227] Furthermore, in this embodiment, base station 100 sets a correspondence between resource information of the UCI of Message A and a group of RACH preamble resource candidates. As a result, in the case of a contention-based RACH, for example, base station 100 can easily control the collision probability of RACH preamble resources or data portion resources by setting the above correspondence in accordance with the bandwidth available to the system or the traffic situation within the cell.

[0228] [Variation 1] In the fourth embodiment, the information transmitted from terminal 200 to base station 100 by UCI is not limited to the TBS and resource information of the data portion, but may also be other parameters related to the transmission of Message A. For example, information related to the transmission power of Message A, MCS, or information related to the transmission rank number of the data portion of Message A may be included in the UCI.

[0229] [Variation 2] The method of transmitting UCI is not limited to multiplexing UCI into the data portion of Message A. For example, UCI may be transmitted using an uplink control channel (PUCCH: Physical Uplink Control Channel).

[0230] The RACH preamble of Message A, the data portion of Message A, and the PUCCH for transmitting UCI may be configured by, for example, TDM, FDM, or CDM.

[0231] The information on the PUCCH format, resource location, and resource amount for transmitting UCI may be associated with, for example, a group of RACH preamble resource candidates. This allows base station 100 to identify in advance the UCI transmission method and the radio resource for transmitting UCI, thereby enabling correct demodulation and decoding of UCI.

[0232] (Embodiment 5) A base station and a terminal according to this embodiment have the same basic configuration as base station 100 and terminal 200 according to the first embodiment, and therefore will be described with reference to FIGS.

[0233] In this embodiment, terminal 200 notifies information about TBS and resource information of the data portion of Message A by a combination of implicit notification associated with a group of RACH preamble resource candidates (see, for example, embodiment 1 or 2) and explicit notification by UCI (see, for example, embodiment 3 or 4).

[0234] For example, information about the TBS in the data portion of Message A is associated with a group of RACH preamble resource candidates (defined by a combination of time resources, frequency resources, and sequence resources, for example) for Message A, as in the first or second embodiment. Meanwhile, resource information in the data portion of Message A is notified by being included in UCI, as in the third or fourth embodiment.

[0235] That is, terminal 200 transmits to base station 100 Message A including a RACH preamble using a RACH preamble resource from a group of RACH preamble resource candidates associated with a TBS dynamically selected by terminal 200, and UCI indicating resource information of the data portion of Message A.

[0236] As described above, according to the present embodiment, it is possible to perform configuration taking into consideration the trade-off between the effect of suppressing an increase in overhead, which is an advantage of implicit notification, and the effect of notification by UCI, which allows for efficient configuration of RACH preamble resources.

[0237] In this embodiment, information regarding the TBS of the data portion of Message A may be notified by being included in UCI as in embodiment 3 or 4, and the resource location or resource amount of the data portion of Message A may be associated with a group of RACH preamble resource candidates (defined by a combination of, for example, time resources, frequency resources, and sequence resources) of Message A as in embodiment 1 or 2.

[0238] For example, information regarding the TBS and information regarding the resource location or resource amount in the data portion of Message A, whichever information has the fewest candidates to be selected, may be notified by UCI. This reduces the number of bits required for notifying UCI.

[0239] Furthermore, the transmission parameters for the data portion of Message A are not limited to TBS and resource information, but may be other parameters.

[0240] The embodiments of the present disclosure have been described above.

[0241] (Other embodiments) (1) The RACH preamble resource candidate group of Message A in the above embodiment is a RACH preamble resource candidate group for a two-step random access procedure.

[0242] For example, base station 100 or terminal 200 may support both a four-step random access procedure and a two-step random access procedure. If base station 100 or terminal 200 supports both random access procedures, the RACH preamble resource candidate set may be divided into a resource group set for the four-step random access procedure and a resource group set for the two-step random access procedure.

[0243] This allows base station 100 to identify which random access procedure terminal 200 has triggered, based on the RACH preamble resource candidate group used by terminal 200.

[0244] (2) In the above embodiment, the resource size of the data portion of Message A may be set to 0.

[0245] In this case, terminal 200 transmits a RACH preamble in Message A, but does not transmit a data portion.

[0246] Furthermore, when the terminal 200 or the base station 100 transmits or receives Message A whose data portion has a size of 0, the terminal 200 or the base station 100 may recognize that the RACH procedure is a four-step RACH procedure (in other words, transmission or reception of Message 1).

[0247] (3) In the above embodiment, the data transmitted by terminal 200 in the data portion of Message A is not limited to C-plane data such as an RRC connection request or a scheduling request, and UP data.

[0248] For example, channel quality information (CQI) may be included in the data transmitted in the data portion of Message A. The CSI acquired in the RACH procedure can be used for subsequent scheduling from base station 100 to terminal 200.

[0249] In this case, the CSI measurement information used by terminal 200 to measure the CQI may be predefined in accordance with the standard, or may be configured in terminal 200 by a higher layer signal (e.g., SIB) transmitted from base station 100 or a terminal-specific RRC signal.

[0250] Furthermore, whether or not Message A includes CSI may be associated with a group of RACH preamble resource candidates for Message A.

[0251] Other embodiments have been described above.

[0252] The present disclosure can be realized by software, hardware, or software in conjunction with hardware. Each functional block described in the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit. Each process described in the above embodiments may be partially or entirely controlled by a single LSI or a combination of LSIs. An LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. An LSI may have data inputs and outputs. Depending on the level of integration, an LSI may be referred to as an IC, system LSI, super LSI, or ultra LSI. The integration method is not limited to LSIs; it may also be realized by dedicated circuits, general-purpose processors, or dedicated processors. Furthermore, a field programmable gate array (FPGA), which can be programmed after LSI fabrication, or a reconfigurable processor, which allows the connections and settings of circuit cells within an LSI to be reconfigured, may also be used. The present disclosure may be realized as digital or analog processing. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology can be used to integrate functional blocks. The application of biotechnology is also a possibility.

[0253] The present disclosure may be implemented in any type of apparatus, device, or system (collectively referred to as a communications apparatus) that has a communications function. The communications apparatus may include a wireless transceiver and processing / control circuitry. The wireless transceiver may include a receiver and a transmitter, or both functions. The wireless transceiver (transmitter and receiver) may include a radio frequency (RF) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, communication-enabled vehicles or mobile transportation (e.g., cars, airplanes, ships), and combinations of the above devices.

[0254] Communications equipment is not limited to portable or mobile equipment, but also includes non-portable or fixed equipment, devices, and systems of any kind, such as smart home devices (such as appliances, lighting equipment, smart meters or metering devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0255] Communications include data communications via cellular systems, wireless LAN systems, communications satellite systems, etc., as well as data communications via combinations of these.

[0256] A communications apparatus also includes devices such as controllers and sensors connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0257] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0258] A terminal according to one embodiment of the present disclosure includes a control circuit that dynamically determines parameters related to transmission of a data portion of a random access signal including a preamble portion and a data portion, and a transmission circuit that notifies a base station of the determined parameters using the random access signal.

[0259] In one embodiment of the present disclosure, the parameter candidates are associated with a group of resource candidates for the preamble portion, and the transmitting circuit transmits the signal for the preamble portion using a resource from the group of resource candidates associated with the determined parameter.

[0260] In one embodiment of the present disclosure, the association between the parameter candidates and the resource candidate group is notified to the terminal by a higher layer signal.

[0261] In an embodiment of the present disclosure, the parameter is a transport block size of the data portion, and the resource candidate groups are associated with the maximum transport block sizes that can be set by the terminal.

[0262] In an embodiment of the present disclosure, the number of resources included in the resource candidate groups varies for each of the resource candidate groups.

[0263] In one embodiment of the present disclosure, the control circuit selects a synchronization signal, a broadcast channel, or a reference signal for channel state estimation according to the determined parameter.

[0264] In one embodiment of the present disclosure, the transmission circuit transmits the random access signal including uplink control information indicating information related to the determined parameters.

[0265] In one embodiment of the present disclosure, the resource of the uplink control information is associated with the resource of the preamble portion.

[0266] In one embodiment of the present disclosure, a candidate for a first parameter among the parameters is associated with a resource candidate group for the preamble portion, and the transmitting circuit transmits the random access signal including a signal for the preamble portion using a resource in the resource candidate group associated with the first parameter, and uplink control information indicating a second parameter among the parameters that is different from the first parameter.

[0267] In one embodiment of the present disclosure, the control circuit determines the parameter based on the amount of data in the data section.

[0268] In one embodiment of the present disclosure, the parameters include at least one of a transport block size, a radio resource, a coding and modulation scheme, a transmission power, and a transmission rank number in the data portion.

[0269] A communication method according to one embodiment of the present disclosure dynamically determines parameters related to transmission of a data portion of a random access signal including a preamble portion and a data portion, and notifies a base station of the determined parameters using the random access signal.

[0270] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2019-024182, filed on February 14, 2019, are incorporated herein by reference in their entirety. [Industrial Applicability]

[0271] An embodiment of the present disclosure is useful in a mobile communication system. [Explanation of symbols]

[0272] 100 base stations 101,209 Control unit 102 Data Generation Unit 103,106,109,211,213 Encoding section 104, 107, 110, 212, 214 Modulation section 105 Upper control signal generation unit 108 Downstream control signal generator 111,215 Signal Allocation Section 112,216 IFFT section 113,217 Transmission Unit 114,201 antennas 115,202 Receiver 116,203 FFT section 117,204 Extraction part 118 Detector 119,205 Demodulation section 120,206,208 Decoding section 200 devices 207 Downstream control signal demodulation unit 210 RACH preamble generation unit

Claims

1. a receiver for receiving a random access signal including a preamble portion and a data portion from a terminal device; a transmitter that, after receiving the random access signal, transmits a MAC layer protocol data unit (PDU) including a response to the random access signal, the MAC layer PDU including transmission timing information for uplink transmission; Equipped with The MAC layer PDU, which is a two-step random access type message B, includes uplink resource information; If the random access procedure is successful, the MAC layer PDU includes the uplink resource information for two-step random access, and the uplink resource information is used to transmit a message of the terminal device; When falling back to the 4-step random access type, the MAC layer PDU includes the uplink resource information for transmitting a message 3 of the 4-step random access type, and the uplink resource information is used to transmit the message 3 of the 4-step random access type. Base station.

2. a size of the data portion is associated with a resource candidate set for the preamble portion, and the preamble portion is transmitted using resources of the resource candidate set. The base station of claim 1.

3. a relationship between the size of the data portion and the resource candidate set is notified by a higher layer signal; The base station according to claim 2.

4. the preamble portion and the data portion are time division multiplexed; The base station of claim 1.

5. The resource candidate set is different between a two-step random access type and a four-step random access type. The base station according to claim 2.

6. The resource is determined based on one synchronization signal block selected from a plurality of synchronization signal blocks, and if there are one or more synchronization signal blocks whose reference signal received power is equal to or greater than a threshold, one of the one or more synchronization signal blocks is selected as the one synchronization signal block, and if there are no one or more synchronization signal blocks whose reference signal received power is equal to or greater than the threshold, any one of the synchronization signal blocks is selected as the one synchronization signal block. The base station according to claim 2.

7. After receiving the random access signal, a MAC layer protocol data unit (PDU) is transmitted, the MAC layer PDU including a response to the random access signal, the MAC layer PDU including information about contention resolution. The base station of claim 1.

8. If the information included in the random access signal matches the information regarding the contention resolution, the terminal device determines that the random access procedure is successful. The base station of claim 7.

9. If the terminal device does not receive a response to the random access signal within a specified period, the random access signal is retransmitted. The base station of claim 1.

10. After receiving the random access signal, a physical downlink channel identified by a Cell-Radio Network Temporary Identifier (C-RNTI) is transmitted. The base station of claim 1.

11. receiving a random access signal including a preamble portion and a data portion from a terminal device; After receiving the random access signal, transmit a MAC layer protocol data unit (PDU) including a response to the random access signal, the MAC layer PDU including transmission timing information for uplink transmission; The MAC layer PDU, which is a two-step random access type message B, includes uplink resource information; If the random access procedure is successful, the MAC layer PDU includes the uplink resource information for two-step random access, and the uplink resource information is used to transmit a message of the terminal device; When falling back to the 4-step random access type, the MAC layer PDU includes the uplink resource information for transmitting a message 3 of the 4-step random access type, and the uplink resource information is used to transmit the message 3 of the 4-step random access type. Communication method.

12. a size of the data portion is associated with a resource candidate set for the preamble portion, and the preamble portion is transmitted using resources of the resource candidate set. The communication method according to claim 11.

13. a relationship between the size of the data portion and the resource candidate set is notified by a higher layer signal; The communication method according to claim 12.

14. the preamble portion and the data portion are time division multiplexed; The communication method according to claim 11.

15. The resource candidate set is different between a two-step random access type and a four-step random access type. The communication method according to claim 12.

16. The resource is determined based on one synchronization signal block selected from a plurality of synchronization signal blocks, and if there are one or more synchronization signal blocks whose reference signal received power is equal to or greater than a threshold, one of the one or more synchronization signal blocks is selected as the one synchronization signal block, and if there are no one or more synchronization signal blocks whose reference signal received power is equal to or greater than the threshold, any one of the synchronization signal blocks is selected as the one synchronization signal block. The communication method according to claim 12.

17. After receiving the random access signal, transmit a MAC layer protocol data unit (PDU) including a response to the random access signal, the MAC layer PDU including information about contention resolution; The communication method according to claim 11.

18. If the information included in the random access signal matches the information regarding the contention resolution, it is determined that the random access procedure is successful.

18. The communication method of claim 17.

19. If the terminal device does not receive a response to the random access signal within a specified period, the random access signal is retransmitted. The communication method according to claim 11.

20. After receiving the random access signal, a physical downlink channel identified by a Cell-Radio Network Temporary Identifier (C-RNTI) is transmitted. The communication method according to claim 11.

21. receiving a random access signal including a preamble portion and a data portion from a terminal device; After receiving the random access signal, transmitting a MAC layer protocol data unit (PDU) including a response to the random access signal, the MAC layer PDU including transmission timing information for uplink transmission; Control the The MAC layer PDU, which is a two-step random access type message B, includes uplink resource information; If the random access procedure is successful, the MAC layer PDU includes the uplink resource information for two-step random access, and the uplink resource information is used to send a message to the terminal device; When falling back to the 4-step random access type, the MAC layer PDU includes the uplink resource information for transmitting a message 3 of the 4-step random access type, and the uplink resource information is used to transmit the message 3 of the 4-step random access type. Integrated circuit.

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