Base station, communication method and integrated circuit

Abstract

To improve the efficiency of random access processing.SOLUTION: A base station includes a transmitting circuit for transmitting a message B which is a transmission response to a random access signal, and a receiving circuit for receiving a response signal to the message B on a PUCCH (Physical Uplink Control Channel) resource determined on the basis of a first parameter included in the message B, and when the message B requests retransmission of a data portion of the random access signal, the receiving circuit receives a message 3 using the resource notified in the message B.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a base station, a communication method, and an integrated circuit. [Background technology]

[0002] The 3GPP (3rd Generation Partnership Project) has completed the Release 15 NR (New Radio access technology) specification for the realization of 5G (5th Generation mobile communication systems). 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 process has not been sufficiently considered.

[0005] Non-limiting embodiments of the present disclosure contribute to providing a base station, a communication method, and an integrated circuit 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 determines resources to be used for transmitting response signals to downlink signals intended for multiple terminals based on parameters that are set for each of the multiple terminals, and a transmission circuit that transmits the response signals in the resources.

[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. 1 is a diagram showing an example of a two-step random access procedure according to the first embodiment. [Figure 8] FIG. 1 is a diagram showing an example of a two-step random access procedure according to the first embodiment. [Figure 9] A diagram showing an example of the structure of Message B [Figure 10] A diagram showing an example of the structure of Message B DETAILED DESCRIPTION OF THE INVENTION

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

[0012] [Random access procedure] In Release 15 NR, a terminal (also referred to as a mobile station or User Equipment (UE)) transmits a random access signal (also referred to as a Random Access Channel (RACH) or Physical RACH (PRACH)) to a base station (also referred to as a gNB or eNB) in the following cases: (1) At initial access (for example, when transitioning from RRC_IDLE state to RRC_CONNECTED state) (2) When returning from RRC_INACTIVE state to RRC_CONNECTED state (3) When downlink or uplink data occurs during connection (for example, when the uplink synchronization state is “non-synchronized” in the RRC_CONNECTED state) (4) When requesting on-demand SI (System Information) 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. A 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 is composed 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 a PRACH preamble resource to be actually used from a group of resource candidates of a preamble signal (hereinafter also referred to as RACH preamble, PRACH preamble or simply preamble) (a resource defined by a combination of, for example, a time resource, a frequency resource and a sequence resource). Then, the terminal transmits the PRACH preamble to the base station (e.g., gNB) using the selected PRACH preamble resource. The PRACH preamble may be referred to as, for example, "Message 1".

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

[0017] The RAR contains information about the resources (uplink resources) used by the terminal, for example, in the transmission of the uplink signal (transmission of Message 3 in Step 3), or information about the uplink transmission timing by the terminal. Here, if the terminal that has transmitted the PRACH preamble does not receive the RAR within a period defined from the transmission timing of the PRACH preamble (for example, called the RAR reception window), it will select the PRACH preamble resource again and transmit the PRACH preamble (in other words, retransmit Message 1).

[0018] <Transmission of Message 3 in Step 3> The terminal uses the uplink resources instructed by the base station via the RAR to transmit "Message 3" including, for example, an RRC (Radio Resource Control) connection request or a scheduling request.

[0019] <Step 4: Transmission of Message 4> The base station transmits a message (referred to as "Message 4") containing identification information (for example, UE-ID) for identifying 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] Above, an example of the 4-step Random access procedure has been described.

[0021] On the other hand, in Release 16 NR, in order to efficiently perform connection or resynchronization establishment from a terminal to a base station with low latency, for example, a Random access procedure (also referred to as a 2-step Random access procedure or a 2-step RACH procedure) composed of two steps as shown in FIG. 2 is under consideration (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 Step 1 and Step 3 of the 4-step Random access procedure (see, for example, FIG. 1) to the base station.

[0023] <Step 2: Transmission of Message B> When the base station detects Message A, it transmits Message B. Message B includes, for example, information corresponding to Message 2 or Message 4 of the 4-step Random access procedure (see, for example, FIG. 1) (for example, either one or both).

[0024] [Retransmission control in Random access procedure] In the 4-step Random access procedure, the transmission of Message 2 is a group cast (or multi-cast) transmission. In Message 2, for example, the MAC PDU (Medium Access Control layer Protocol Data Unit) includes MAC RAR (or MAC subPDU) for one or more terminals. Also, for Message 2, HARQ (Hybrid Automatic Repeat Request), which is retransmission control, is not applied.

[0025] In the four-step random access procedure, Message 4 is transmitted via unicast, and HARQ is applied to Message 4.

[0026] On the other hand, in the two-step Random access procedure, Message B includes at least a MAC PDU including a RACH response (e.g., RAR) and a MAC PDU including a message (e.g., Contention resolution MAC CE) including identification information (e.g., UE-ID) for identifying the terminal.

[0027] For example, if Message B is transmitted by unicast transmission like Message 4 in the four-step random access procedure, base station 100 will schedule Message B for all terminals that have performed random access by using a downlink control channel (for example, PDCCH: Physical Downlink Control Channel). In this case, for example, as the number of terminals that perform random access increases, there is a possibility that the overhead of the downlink control channel will increase.

[0028] Therefore, it is assumed that Message B will be transmitted as a groupcast transmission, similar to Message 2 in the four-step random access procedure, which will reduce the overhead of the downlink control channel.

[0029] Furthermore, in addition to the MAC PDU including the RAR and the MAC PDU including the UE-ID, Message B may also include a MAC PDU including, for example, an RRC (Radio Resource Control) signal related to RRC connection, RRC recovery, and RRC reconnection. By including a MAC PDU including an RRC signal in Message B, the delay of the two-step random access procedure can be further reduced.

[0030] However, the RRC signal has a larger data volume than other signals. Therefore, it is expected that the utilization efficiency of downlink resources can be improved by applying HARQ to Message B, for example, as with Message 4 of the four-step random access procedure. When HARQ is applied to Message B, the terminal transmits a response signal (for example, ACK / NACK: Acknowledgement / Negative Acknowledgment) indicating the result of error detection of downlink data (for example, RRC signal) to the base station in the uplink.

[0031] However, a method for transmitting an ACK / NACK signal in response to Message B transmitted via groupcast in the two-step random access procedure has not been fully investigated.

[0032] For example, Release 15 NR introduces allocation of uplink control channel (e.g., PUCCH: Physical Uplink control channel) resources (hereinafter referred to as PUCCH resources) for transmitting ACK / NACK signals for Message 4 (see, for example, Non-Patent Document 3).

[0033] For example, the base station notifies the terminal in advance of a resource configuration (e.g., a PUCCH resource set) indicating a combination of multiple parameters related to PUCCH resources by using a cell-specific higher layer signal (e.g., Remining Minimum System Information (RMSI)) such as a System Information Block (SIB). For example, in Release 15 NR, the PUCCH resource set includes a combination of parameters related to 16 PUCCH resources.

[0034] In addition, the base station selects one combination of parameters related to the PUCCH resources that the terminal will actually use from the PUCCH resource set based on some bits in the PDCCH that schedule Message 4 (for example, 3 bits in Release 15 NR) and the CCE (Control Channel Element) number, which is the resource allocation information of the PDCCH.

[0035] For example, the parameter combination r for the PUCCH resource PUCCH (For example, 16 numbers from 0 to 15) are given by the following formula: r PUCCH = ceiling (2n CCE / N CCE ) + 2Δ PRI (1)

[0036] In formula (1), n CCE represents the CCE number, and N CCE represents the number of CCEs, and Δ PRI represents a value (for example, any of 0 to 7) that is explicitly notified by some bits (for example, 3 bits) of the PDCCH.

[0037] Here, since the transmission of Message 4 is a unicast transmission, Message 4 for each terminal is scheduled by a different PDCCH. Therefore, for example, when the base station uses a combination of parameters related to the PUCCH resource shown in Equation (1) and Δ PRI By appropriately setting and, there is no collision of PUCCH resources between terminals for ACK / NACK signals for Message 4.

[0038] On the other hand, if Message B is transmitted as a groupcast transmission, Message B includes MAC PDUs for multiple terminals. Therefore, depending on the channel state of each terminal, there is a possibility that some terminals can correctly decode the MAC PDU and some terminals cannot decode the MAC PDU. In other words, the decoding results (ACK / NACK signals) of the MAC PDU of Message B (e.g., the MAC PDU including the RRC signal) at each terminal may differ from terminal to terminal.

[0039] However, when Message B is transmitted as a groupcast transmission, the base station schedules Message B, which includes MAC PDUs addressed to multiple terminals, using one PDCCH. Therefore, for example, in the PUCCH resource allocation for Message 4 of Release 15 NR shown in equation (1), the same PUCCH resource is allocated to all terminals. Therefore, when each terminal transmits an ACK / NACK signal to the base station according to the decoding result of the MAC PDU of Message B, all terminals transmit the ACK / NACK signal using the same PUCCH resource. In other words, there may be a collision of PUCCH resources between terminals for the ACK / NACK signals for Message B.

[0040] For example, when a base station uses Δ PRI By including and transmitting the ACK / NACK signal for Message B (see, for example, Equation (1)), it is possible to suppress collisions of PUCCH resources between terminals for the ACK / NACK signal for Message B. However, in this case, the overhead of the PDCCH increases. For example, as in Release 15 NR, PRI Assuming this, an overhead of 3 bits times the number of terminals (in other words, the number of users) may occur.

[0041] Therefore, in one embodiment of the present disclosure, a method for transmitting an ACK / NACK signal for Message B in a case where Message B is transmitted by groupcast transmission in a two-step random access procedure will be described. According to one embodiment of the present disclosure, it is possible to suppress PDCCH resource collisions between terminals while suppressing PDCCH overhead.

[0042] Each embodiment will be described in detail below.

[0043] (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.

[0044] 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) determines resources to be used for transmitting response signals (e.g., ACK / NACK signals) in response to downlink signals (e.g., Message B) addressed to multiple terminals, based on parameters set for each of the multiple terminals. Transmitting unit 218 transmits the response signals in the resources.

[0045] [Base station configuration] Fig. 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 retransmission control unit 104, a modulation unit 105, an upper control signal generation unit 106, an encoding unit 107, a modulation unit 108, a downlink control signal generation unit 109, an encoding unit 110, a modulation unit 111, a signal allocation unit 112, an IFFT (Inverse Fast Fourier Transform) unit 113, a transmission unit 114, an antenna 115, a reception unit 116, an FFT (Fast Fourier Transform) unit 117, an extraction unit 118, a detection unit 119, a demodulation unit 120, and a decoding unit 121.

[0046] Control section 101 determines information for transmitting Message A from terminal 200 (or also referred to as transmission parameters of Message A), and outputs the determined information to extraction section 118, demodulation section 120, and decoding section 121. Control section 101 also outputs the determined information to higher control signal generation section 106. The information for transmitting Message A may include, for example, information on the PRACH preamble resource of Message A, the PUSCH resource, and the TBS (Transport Block Size) or MCS of the PUSCH.

[0047] 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 (including, for example, scheduling information) to the coding units 103, 107, and 110, the modulation units 105, 108, and 111, and the signal allocation unit 112. The control unit 101 also outputs the determined information to the downlink control signal generation unit 109.

[0048] Furthermore, the control unit 101 determines information to be included in Message B based on the decoding result of Message A (e.g., C-Plane data or UP (User Plane) data) input from the decoding unit 121 and the detection result of Message A (e.g., PRACH preamble) input from the detection unit 119, and outputs the determined information to the data generation unit 102.

[0049] Furthermore, control section 101 determines information related to PUCCH resources for terminal 200 to transmit an ACK / NACK signal for Message B. Control section 101 outputs the determined information to higher control signal generation section 106, downlink control signal generation section 109, data generation section 102, or extraction section 118.

[0050] 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.

[0051] Encoding section 103 performs error coding on the information bit string (data signal) input from data generation section 102 and outputs the coded data signal to retransmission control section 104.

[0052] At the time of the first transmission, retransmission control section 104 outputs the coded data signal input from coding section 103 to modulation section 105. Retransmission control section 104 also holds the coded data signal. When retransmission control section 104 receives a NACK for the transmitted data signal from decoding section 121, it outputs the corresponding held data to modulation section 105, and when it receives an ACK for the transmitted data, it deletes the corresponding held data.

[0053] Modulation section 105 modulates the data signal input from retransmission control section 104 and outputs the modulated data signal to signal allocation section 112 .

[0054] Higher-order control signal generating section 106 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 107 .

[0055] Encoding section 107 performs error correction coding on the control information bit string inputted from higher-order control signal generating section 106 and outputs the coded control signal to modulation section 108 .

[0056] Modulation section 108 modulates the control signal inputted from encoding section 107 and outputs the modulated control signal to signal allocation section 112 .

[0057] The downlink control signal generating unit 109 generates a control information bit string (downlink control signal, for example, DCI: Downlink Control Information) using the control information input from the control unit 101, and outputs the generated control information bit string to the encoding unit 110. Note that since control information may be transmitted to multiple terminals, the downlink control signal generating unit 109 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).

[0058] The coding section 110 performs error correction coding on the control information bit string inputted from the downlink control signal generating section 109 and outputs the coded control signal to the modulating section 111 .

[0059] Modulation section 111 modulates the control signal input from encoding section 110 and outputs the modulated control signal to signal allocation section 112 .

[0060] The signal allocation unit 112 maps the data signal input from the modulation unit 105, the higher control signal input from the modulation unit 108, or the downlink control signal input from the modulation unit 111 to the radio resources based on the information indicating the radio resources input from the control unit 101. The signal allocation unit 112 outputs the downlink signal onto which the signal has been mapped to the IFFT unit 113.

[0061] The IFFT unit 113 performs transmission waveform generation processing such as OFDM (Orthogonal Frequency Division Multiplexing) on ​​the signal input from the signal allocation unit 112. In the case of OFDM transmission that adds a CP (Cyclic Prefix), the IFFT unit 113 adds a CP (not shown). The IFFT unit 113 outputs the generated transmission waveform to the transmission unit 114.

[0062] Transmitting section 114 performs RF (Radio Frequency) processing such as D / A (Digital-to-Analog) conversion and up-conversion on the signal input from IFFT section 113 , and transmits the radio signal to terminal 200 via antenna 115 .

[0063] The receiving unit 116 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 115, and outputs the uplink signal waveform after the receiving processing to the FFT unit 117.

[0064] The FFT unit 117 performs FFT processing on the uplink signal waveform input from the receiving unit 116 to convert a time domain signal into a frequency domain signal. The FFT unit 117 outputs the frequency domain signal obtained by the FFT processing to the extracting unit 118.

[0065] Based on the information input from the control unit 101, the extraction unit 118 extracts a radio resource portion on which a PRACH preamble is transmitted or a radio resource portion on which a PUSCH of Message A is transmitted from the signal input from the FFT unit 117. The extraction unit 118 outputs the extracted radio resource portion on which the PRACH preamble is transmitted to the detection unit 119, and outputs a radio resource portion on which a signal other than the PRACH preamble (for example, the PUSCH of Message A) is transmitted to the demodulation unit 120. Furthermore, based on the information input from the control unit 101, the extraction unit 118 extracts an ACK / NACK signal for Message B from the signal input from the FFT unit 117, and outputs the extracted signal to the demodulation unit 120.

[0066] The detector 119 detects the PRACH preamble for the radio resource portion corresponding to the PRACH preamble received as input from the extractor 118. The detector 119 outputs information relating to the detection result of the PRACH preamble to the control unit 101.

[0067] Based on the information input from the control unit 101, the demodulation unit 120 demodulates the data of Message A input from the extraction unit 118 or the ACK / NACK signal for Message B, and outputs the demodulation result (demodulated sequence) to the decoding unit 121.

[0068] The decoding unit 121 performs error correction decoding on the demodulation result input from the demodulation unit 120 based on the information input from the control unit 101, and outputs a decoded bit sequence (including, for example, C-Plane data or UP data). Also, for example, the decoding unit 121 outputs the decoded result of Message A to the control unit 101.

[0069] Furthermore, decoding section 121 decodes the ACK / NACK signal for Message B based on the demodulation result input from demodulation section 120, and determines whether the ACK / NACK signal for the transmitted data signal indicates an ACK or a NACK. Decoding section 121 outputs the determination result (ACK or NACK) to retransmission control section 104.

[0070] [Device configuration] Fig. 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, PRACH preamble generation section 210, ACK / NACK generation section 211, coding section 212, modulation section 213, coding section 214, modulation section 215, signal allocation section 216, IFFT section 217, and transmission section 218.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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 .

[0075] 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 208 outputs the obtained received data or control information to control section 209. Decoding section 206 also performs error detection on the received data, and outputs the error detection result (e.g., whether there is an error or not) to ACK / NACK generation section 211.

[0076] 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 .

[0077] 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.

[0078] The control unit 209 determines parameters for uplink transmission (for example, transmission of Message A) based on the control information input from the decoding unit 206 or the decoding unit 208. The control unit 209 outputs the determined information to the PRACH preamble generation unit 210, the coding units 212 and 214, the modulation units 213 and 215, and the signal allocation unit 216.

[0079] Furthermore, control section 209 determines information related to the transmission of an ACK / NACK signal (for example, uplink resources, transmission method or parameters, etc.) based on information related to resources for transmitting an ACK / NACK signal for Message B, which is input from decoding section 206 or decoding section 208. Control section 209 outputs the determined information to coding section 212, modulation section 213 and signal allocation section 216.

[0080] 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.

[0081] The PRACH preamble generating unit 210 generates a PRACH preamble based on control information received as input from the control unit 209 (for example, transmission parameters of Message A), and outputs the generated PRACH preamble to the signal allocating unit 216 .

[0082] The ACK / NACK generation unit 211 generates an ACK / NACK signal for the received downlink data (e.g., Message B) based on the error detection result input from the decoding unit 206, and outputs the ACK / NACK signal (e.g., an ACK / NACK signal sequence) to the encoding unit 212.

[0083] The encoding unit 212 performs error correction encoding on the ACK / NACK signal sequence input from the ACK / NACK generation unit 211 based on information input from the control unit 209 (e.g., information regarding the transmission of an ACK / NACK signal), and outputs the encoded ACK / NACK signal sequence to the modulation unit 213.

[0084] The modulation unit 213 modulates the ACK / NACK signal sequence input from the encoding unit 212 based on information input from the control unit 209, and outputs the modulated ACK / NACK signal (modulation symbol sequence) to the signal allocation unit 216.

[0085] The encoding unit 214 performs error correction encoding on, for example, an information bit sequence (e.g., C-Plane data and UP data) transmitted in the data portion of Message A based on control information (e.g., transmission parameters of Message A) input from the control unit 209, and outputs the encoded bit sequence to the modulation unit 215.

[0086] Modulation section 215 modulates the bit sequence input from encoding section 214 based on information input from control section 209 , and outputs a data signal (modulation symbol sequence) to signal allocation section 216 .

[0087] The signal allocation unit 216 maps the signal input from the PRACH preamble generation unit 210, the signal input from the modulation unit 213, or the signal input from the modulation unit 215 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 217.

[0088] The IFFT unit 217 performs transmission waveform generation processing such as OFDM on the signal input from the signal allocation unit 216. In the case of OFDM transmission that adds a CP, the IFFT unit 217 adds a CP (not shown). Alternatively, in the case where the IFFT unit 217 generates a single-carrier waveform, a DFT (Discrete Fourier Transform) unit may be added (not shown) before the signal allocation unit 216. The IFFT unit 217 outputs the generated transmission waveform to the transmission unit 218.

[0089] The transmitter 218 performs RF processing such as D / A conversion and up-conversion on the signal input from the IFFT unit 217 , and transmits the radio signal to the base station 100 via the antenna 201 .

[0090] [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.

[0091] FIG. 6 shows an example of a flow of processing for transmitting and receiving an ACK / NACK signal for Message B in base station 100 and terminal 200 according to this embodiment.

[0092] 6, base station 100 reports, for example, information about uplink resources (for example, PUCCH resources) to terminal 200 (ST101). The information about PUCCH resources includes, for example, information about PUCCH resources for transmitting an ACK / NACK signal for Message B. Terminal 200 acquires the information about the PUCCH resources (ST102).

[0093] Base station 100 transmits, for example, scheduling information including allocation information of Message B to terminal 200 (ST103). The scheduling information of Message B may be transmitted, for example, by the PDCCH. Terminal 200 acquires the scheduling information of Message B (ST104).

[0094] Base station 100 transmits Message B to terminal 200, for example, based on the scheduling information in Message B (ST105).

[0095] Upon receiving Message B, terminal 200 demodulates and decodes Message B (ST106). Terminal 200 also generates an ACK / NACK signal for Message B.

[0096] Terminal 200 determines an uplink resource for transmitting an ACK / NACK signal for Message B (e.g., an RRC signal) based on, for example, at least one of information on PUCCH resources, scheduling information (e.g., PDCCH), and Message B (e.g., RAR) (ST107).

[0097] Then, terminal 200 transmits an ACK / NACK signal for Message B to base station 100 based on the determined uplink resource (ST108).

[0098] [How to send ACK / NACK signals for Message B] Next, an example of a method for transmitting an ACK / NACK signal for Message B will be described.

[0099] In this embodiment, terminal 200 transmits an ACK / NACK signal for Message B, for example, on the PUCCH.

[0100] At this time, terminal 200 determines the PUCCH resource for transmitting an ACK / NACK signal for Message B, for example, based on notification of the PUCCH resource for transmitting an ACK / NACK signal for Message 4 of the four-step random access procedure (for example, the parameter shown in equation (1)) and a new parameter "X." Parameter X may be, for example, a value set for each of multiple terminals 200 to which Message B is addressed.

[0101] First, operation example 1 and operation example 2 of the two-step RACH procedure in this embodiment will be described below.

[0102] Here, as an example, a case will be described in which three terminals 200 (for example, UE#A, UE#B, and UE#C) transmit Message A to a base station 100 (for example, a gNB).

[0103] [Operation Example 1] FIG. 7 shows an example of a two-step RACH procedure in Operation Example 1.

[0104] <Transmission of Message A> Each terminal 200 transmits Message A to the base station 100.

[0105] Message A includes, for example, a RACH preamble (e.g., any one of Preamble #1 to #3), and a PUSCH (e.g., a data part or a UCI + data part). Also, the PUSCH includes, for example, a UE-ID (e.g., any one of UE-ID #A, UE-ID #B, and UE-ID #C) for identifying the terminal 200.

[0106] Also, each terminal 200 operates a "Msg.B reception window" (in other words, a timer), which is a reception possible period for Message B, from the transmission timing of the RACH preamble (in other words, Message A).

[0107] <Transmission of Message B> When the base station 100 detects Message A transmitted from each terminal 200 and correctly decodes it, the base station 100 transmits Message B. Message B includes, for example, a message (e.g., MAC RAR and MAC CE) including a RAR and a UE-ID for identifying the terminal 200.

[0108] On the other hand, when the base station 100 cannot detect Message A (e.g., a PRACH preamble) or cannot correctly decode Message A (e.g., a PUSCH), the base station 100 does not include information addressed to the terminal 200 that transmitted the corresponding Message A in Message B.

[0109] For example, in the example shown in FIG. 7, the base station 100 (gNB) detects the Preamble #1 of Message A transmitted from UE#A (detection result: ○) and correctly decodes the PUSCH (decoding result: ○). On the other hand, the base station 100 (gNB) detects the Preamble #2 of Message A transmitted from UE#B (detection result: ○) but cannot correctly decode the PUSCH (decoding result: ×). Also, the base station 100 (gNB) cannot detect the Preamble #1 of Message A transmitted from UE#C (detection result: ×) and cannot correctly decode the PUSCH (decoding result: ×).

[0110] Therefore, in the example shown in FIG. 7, the base station 100 generates a RAR for UE#A and Message B including the UE-ID#A of UE#A. In other words, in FIG. 7, Message B does not include information addressed to UE#B and UE#C.

[0111] <Reception of Message B> If the terminal 200 that transmitted Message A does not receive Message B including information addressed to the terminal 200 within the Msg.B reception window period, it retransmits Message A (in other words, performs the Random access process again from the transmission of Message A). In the example shown in FIG. 7, UE#B and UE#C do not receive Message B addressed to UE#B and UE#C within the Msg.B reception window period, so they retransmit Message A.

[0112] On one hand, the terminal 200 that sent Message A receives Message B containing information addressed to the terminal 200 within the period of the Msg.B reception window. If the UE-ID included in Message B matches the UE-ID included in the sent Message A, it is determined that the RACH procedure has succeeded. In the example shown in FIG. 7, UE#A receives Message B addressed to UE#A within the period of the Msg.B reception window, and the UE-ID (UE-ID#A) included in the Message B matches the UE-ID (UE-ID#A) included in the sent Message A, so it is determined that the RACH procedure has succeeded (RA procedure: ○).

[0113] <Operation Example 2> FIG. 8 shows an example of the two-step RACH procedure in Operation Example 2.

[0114] <Transmission of Message A> Each terminal 200 transmits Message A to the base station 100.

[0115] Similar to Operation Example 1, Message A includes, for example, a RACH preamble (e.g., any one of Preamble#1~#3), and a PUSCH (e.g., a data part, or a UCI + data part). Also, the PUSCH includes, for example, a UE-ID (e.g., any one of UE-ID#A, UE-ID#B, and UE-ID#C) for identifying the terminal 200.

[0116] Also, each terminal 200 operates a "Msg.B reception window" (in other words, a timer), which is the receivable period of Message B, from the transmission timing of the RACH preamble (in other words, Message A).

[0117] <Transmission of Message B> When base station 100 detects Message A transmitted from each terminal 200 and correctly decodes it, it transmits Message B. Message B includes, for example, a message including RAR and a UE-ID for identifying terminal 200 (for example, MAC RAR and MAC CE).

[0118] Base station 100 also transmits Message B if it detects a RACH preamble of Message A transmitted from each terminal 200 and is unable to correctly decode the data portion. If base station 100 detects a 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, in this case, for example, Message B includes an RAR (in other words, it does not include a UE-ID). RAR may include, for example, information regarding 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.

[0119] On the other hand, if base station 100 is unable to detect Message A (for example, a PRACH preamble), it does not include in Message B information addressed to terminal 200 that transmitted the corresponding Message A.

[0120] For example, in the example shown in FIG. 8, similar to operation example 1 (e.g., FIG. 7), the base station 100 (gNB) detects Preamble #1 of Message A transmitted from UE #A (detection result: ○) and correctly decodes the PUSCH (decoding result: ○). On the other hand, the base station 100 (gNB) detects Preamble #2 of Message A transmitted from UE #B (detection result: ○) but cannot correctly decode the PUSCH (decoding result: ×). Furthermore, the base station 100 (gNB) cannot detect Preamble #1 of Message A transmitted from UE #C (detection result: ×) and cannot correctly decode the PUSCH (decoding result: ×).

[0121] Therefore, in the example shown in FIG. 8, the base station 100 generates Message B including the RAR for UE#A, the UE-ID #A of UE#A, and the RAR for UE#B. In other words, in FIG. 7, Message B does not include information addressed to UE#C.

[0122] <Reception of Message B> If the terminal 200 that transmitted Message A does not receive Message B including information addressed to the terminal 200 within the Msg.B reception window period, the terminal 200 retransmits Message A (in other words, performs the random access process again from the transmission of Message A). In the example shown in FIG. 8, since UE#C does not receive Message B addressed to UE#C within the Msg.B reception window period, UE#C retransmits Message A.

[0123] On the other hand, if the terminal 200 that transmitted Message A receives Message B including information addressed to the terminal 200 within the Msg.B reception window period, but the UE-ID included in Message B does not match the UE-ID included in the transmitted Message A, uplink transmission is performed according to the information included in the RAR corresponding to Message A (for example, the PRACH preamble). In the example shown in FIG. 8, although UE#B receives Message B (for example, RAR) addressed to UE#B within the Msg.B reception window period, the UE-ID (UE-ID#A) included in the Message B does not match the UE-ID (UE-ID#B) included in the transmitted Message A, so it is determined that the RACH procedure has not been successful yet (RA procedure: ×). UE#B may retransmit the PUSCH, for example, based on the information included in the RAR for UE#B in Message B. In other words, UE#B may fallback to the transmission of Message 3 in the 4-step random access procedure.

[0124] Furthermore, terminal 200 that transmitted Message A receives Message B including information addressed to terminal 200 within the Msg.B reception window, and determines that the RACH procedure has been successful if the UE-ID included in Message B matches the UE-ID included in the transmitted Message A. In the example shown in Fig. 8, UE#A receives Message B addressed to UE#A within the Msg.B reception window, and the UE-ID (UE-ID#A) included in Message B matches the UE-ID (UE-ID#A) included in the transmitted Message A, and therefore determines that the RACH procedure has been successful (RA procedure: O).

[0125] Operation examples 1 and 2 of the two-step random access procedure have been described above.

[0126] As described above, if base station 100 detects and correctly decodes Message A, Message B includes a MAC PDU including an RAR and a MAC PDU including a message including a UE-ID for identifying terminal 200 (e.g., Contention resolution MAC CE).

[0127] Furthermore, the MAC PDU including the RAR may include, for example, information regarding the transmission timing of an uplink signal in terminal 200, a TC-RNTI (Temporary C-RNTI), or information regarding resources used by terminal 200 in the uplink.

[0128] Furthermore, Message B may include, in addition to the MAC PDU including the RAR and the UE-ID, a MAC PDU including, for example, an RRC signal for RRC connection, RRC recovery, and RRC reconnection.

[0129] 9 and 10 show configuration examples of Message B. Fig. 9 shows an example in which Message B does not include a MAC PDU including an RRC signal, and Fig. 10 shows an example in which Message B includes a MAC PDU including an RRC signal.

[0130] For example, when terminal 200 receives Message B containing information addressed to terminal 200, and if the UE-ID contained in Message B matches the UE-ID contained in the transmitted Message A, and if Message B contains a MAC PDU containing an RRC signal addressed to terminal 200, terminal 200 decodes the MAC PDU containing the RRC signal and transmits an ACK / NACK signal corresponding to the decoding result (or the error detection result) to base station 100 in an uplink resource (e.g., a PUCCH resource).

[0131] A method for determining a PUCCH resource for transmitting an ACK / NACK signal will be described below.

[0132] Base station 100 notifies terminal 200 in advance of a resource configuration (e.g., a PUCCH resource set) indicating a combination of multiple parameters related to PUCCH resources, for example, by a cell-specific higher layer signal such as an SIB (e.g., RMSI). For example, in Release 15 NR, a PUCCH resource set includes 16 parameter combinations related to PUCCH resources. Note that the number of parameter combinations related to PUCCH resources included in a PUCCH resource set is not limited to 16 and may be any other number.

[0133] Furthermore, base station 100 selects one combination of parameters related to the PUCCH resource that terminal 200 will actually use from the PUCCH resource set based on some bits in the PDCCH that schedule Message B (for example, 3 bits in Release 15 NR), the CCE number of the PDCCH, and the additional notification information "X."

[0134] For example, the parameter combination r for the PUCCH resource PUCCH (For example, 16 numbers from 0 to 15) are given by the following formula: r PUCCH = ceiling (2n CCE / N CCE ) + 2Δ PRI + X (2)

[0135] In formula (2), n CCE represents the CCE number, and N CCE represents the number of CCEs, and Δ PRI represents a value (any of 0 to 7) explicitly notified by 3 bits of the PDCCH. PRI is not limited to the 3 bits of the PDCCH, but may be any other number of bits.

[0136] In this way, terminal 200 may use, for example, a value (for example, Δ PRI ) and the resource to which the PDCCH is allocated (for example, n CCE ) and parameter "X" that is set for each terminal 200. In other words, terminal 200 determines the PUCCH resource for transmitting an ACK / NACK signal for Message B based on a method (e.g., see equation (2)) that is different from the method (e.g., see equation (1)) for determining the PUCCH resource for transmitting an ACK / NACK signal for Message 4 of the four-step random access procedure.

[0137] In equation (2), parameter "X" may be reported from base station 100 to terminal 200 explicitly or implicitly by, for example, the following methods (any one or a combination of Options 1 to 5).

[0138] <option 1> The parameter "X" may be included in the MAC RAR of Message B (in other words, information regarding the response to Message A (PRACH preamble)).

[0139] In addition to parameter "X", the MAC PDU including the RAR may include information on the uplink transmission timing in terminal 200, TC-RNTI, or information on resources used by terminal 200 on the uplink.

[0140] < / option> <option 2> The parameter “X” may be a value associated with the UE-ID included in Message A transmitted by terminal 200.

[0141] For example, the association may be such that X = UE-ID mod Y, where Y is the number of combinations of multiple parameters related to PUCCH resources included in the PUCCH resource set, and Y = 16 in Release 15 NR.

[0142] < / option> <option 3> The parameter "X" may be a value associated with the arrangement order (for example, referred to as the RAR order) of RARs in Message B that correspond to the multiple terminals 200 respectively.

[0143] For example, Message B shown in Fig. 10 includes RARs in the order of MAC subPDU3A, MAC subPDU4A, etc. Furthermore, in Message B shown in Fig. 10, the RRC signal addressed to terminal 200 corresponding to MAC subPDU3A is included in MAC subPDU3C, and the RRC signal addressed to terminal 200 corresponding to MAC subPDU4A is included in MAC subPDU4C.

[0144] In this case, for example, X=0 may be set for terminal 200 corresponding to MAC subPDU3C (e.g., the first RAR) and X=1 may be set for terminal 200 corresponding to MAC subPDU4C (e.g., the second RAR) based on the order (arrangement order) in which RARs are included in Message B. Note that the number of RARs included in Message B and the value of X associated with the arrangement order of RARs are not limited to these.

[0145] < / option> <option 4> The parameter “X” may be a value associated with the RACH preamble number (eg, PAID) used in Message A transmitted by terminal 200.

[0146] For example, the association may be such that X = PAID mod Y, where Y is the number of combinations of multiple parameters for PUCCH resources included in the PUCCH resource set, and Y = 16 in Release 15 NR.

[0147] < / option> <option 5> Parameter “X” may be a value associated with a port number (eg, DMRS port number) of a PUSCH reference signal (eg, DMRS: Demodulation Reference Signal) used in Message A transmitted by terminal 200.

[0148] For example, they may be related as follows: X = DMRS port index mod Y, where Y is the number of combinations of multiple parameters for PUCCH resources included in the PUCCH resource set, and Y = 16 in Release 15 NR.

[0149] The notification methods (Options 1 to 5) for parameter "X" have been explained above.

[0150] According to the five options described above, parameter "X" is reported to terminal 200 without increasing PDCCH overhead.

[0151] Furthermore, for example, each terminal 200 can select a combination r of parameters related to PUCCH resources using equation (2) including parameter “X”. PUCCH can be selected for each terminal 200. In other words, terminal 200 can individually determine the PUCCH resource for transmitting an ACK / NACK signal for Message B transmitted by groupcast (in other words, a signal addressed to multiple terminals 200) based on parameter "X" set for each terminal 200. Therefore, collision of PUCCH resources between terminals 200 can be reduced when transmitting an ACK / NACK signal for Message B (for example, an RRC signal).

[0152] Therefore, according to the present embodiment, even when Message B (including, for example, an RRC signal) is transmitted by groupcast, it is possible to suppress collision of PUCCH resources between terminals 200 when transmitting ACK / NACK signals in response to the RRC signal, without increasing PDCCH overhead. As a result, in the present embodiment, it is possible to improve the efficiency of random access processing (for example, retransmission control) in Message B of the two-step random access procedure.

[0153] Note that any one of the above-mentioned Options 1 to 5 may be applied, or a combination of multiple Options may be applied.

[0154] Furthermore, this embodiment is not limited to the case where terminal 200 determines the PUCCH using parameter "X" in addition to some bits of the PDCCH used to schedule Message B (for example, 3 bits in Release 15 NR) and CCE numbers that are PDCCH resource allocation information. For example, terminal 200 may determine the PUCCH resource using parameter "X" without using some bits of the PDCCH used to schedule Message B and CCE numbers. In this case, PDCCH overhead can be further reduced.

[0155] Furthermore, when Message B supports multiple transmission methods, such as groupcast and unicast, terminal 200 may determine PUCCH resources according to the transmission method of Message B. For example, when groupcast transmission is configured for Message B, terminal 200 determines PUCCH resources using parameter "X" (see, for example, equation (2)), whereas when unicast transmission is configured, terminal 200 may determine PUCCH resources without using parameter "X" (see, for example, equation (1)).

[0156] (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.

[0157] In this embodiment, terminal 200 transmits an ACK / NACK signal for Message B on an uplink control channel (for example, PUCCH).

[0158] At this time, base station 100 notifies terminal 200 of the PUCCH resource for transmitting the ACK / NACK signal, for example, by using uplink allocation information (for example, referred to as an UL grant) included in the RAR of Message B. Terminal 200 determines the PUCCH resource for transmitting the ACK / NACK signal for Message B (for example, an RRC signal), for example, based on the UL grant included in the RAR of Message B addressed to terminal 200.

[0159] For example, in operation example 2 of the two-step random access procedure in embodiment 1 (see, for example, FIG. 8), when base station 100 detects and correctly decodes Message A, it transmits Message B. At this time, Message B includes a message including RAR and a UE-ID for identifying terminal 200.

[0160] In the present embodiment, when base station 100 detects and correctly decodes Message A, it notifies, in the UL grant included in the RAR, uplink resources (for example, PUCCH resources) for transmitting an ACK / NACK signal for Message B (for example, an RRC signal). Terminal 200 receives Message B including information addressed to terminal 200, and, if the UE-ID included in Message B matches the UE-ID transmitted in Message A and if Message B includes a MAC PDU including an RRC signal addressed to terminal 200, it decodes the MAC PDU and transmits the decoding result (for example, an ACK / NACK signal) to base station 100 in the PUCCH resources notified in the UL grant.

[0161] For example, in the example shown in Fig. 8, base station 100 (gNB) detects Preamble #1 of Message A transmitted from UE #A (detection result: ○) and correctly decodes the PUSCH (decoding result: ○). Therefore, base station 100 sets, in Message B, a PUCCH resource for transmitting an ACK / NACK signal for Message B in the UL grant included in the RAR for UE #A. UE #A transmits an ACK / NACK signal for Message B based on the PUCCH resource indicated in the UL grant included in the RAR for UE #A included in Message B.

[0162] Furthermore, in operation example 2 of the two-step random access procedure in embodiment 1 (see, for example, FIG. 8), base station 100 detects the RACH preamble of Message A, and also transmits Message B if it is unable to correctly decode the data portion. At this time, Message B includes an RAR. RAR may include, for example, information regarding a request for retransmission of the data portion to terminal 200 that transmitted the corresponding RACH preamble, and information regarding resources used in the uplink by terminal 200 (UL grant).

[0163] In the present embodiment, for example, when base station 100 detects the RACH preamble of Message A (Message A of UE#B in FIG. 8) and is unable to correctly decode the data portion, it notifies, in an UL grant included in an RAR, of uplink resources (e.g., PUSCH resources) for retransmitting the data portion of Message A (e.g., PUSCH). Terminal 200 (UE#B in FIG. 8) retransmits the data portion of Message A (e.g., PUSCH) based on the PUSCH resources indicated in the UL grant included in the RAR of Message B for terminal 200.

[0164] The RAR may include a flag that identifies whether the UL grant indicates uplink resources for retransmission of Message A (e.g., PUSCH) or PUCCH resources for transmitting an ACK / NACK signal for Message B.

[0165] In Release 15 NR, for example, the UL grant included in the RAR is configured with a 27-bit field. In this embodiment, for example, a part of the 27-bit field included in the UL grant may be used to notify the PUCCH resource for transmitting an ACK / NACK signal for Message B. Note that the size of the field included in the UL grant is not limited to 27 bits.

[0166] Furthermore, for example, if the number of combinations of multiple parameters related to PUCCH resources included in a PUCCH resource set is 16 as in Release 15 NR, 4 bits may be used to report PUCCH resources for transmitting an ACK / NACK signal for Message B, and the remaining field may be used for other purposes or may be reserved. Note that the number of bits used to report PUCCH resources is not limited to 4 bits.

[0167] According to the present embodiment, base station 100 notifies, by means of an UL grant included in the RAR of Message B, of PUCCH resources for transmitting an ACK / NACK signal for Message B. In other words, base station 100 can configure (in other words, schedule) PUCCH resources for each terminal 200 in the UL grant included in the RAR for each terminal 200 of Message B.

[0168] This allows terminal 200 to individually determine the PUCCH resource for transmitting an ACK / NACK signal for Message B transmitted via groupcast (in other words, a signal addressed to multiple terminals 200), based on the UL grant set for each terminal 200. This makes it possible to reduce collisions of PUCCH resources between terminals 200 when transmitting an ACK / NACK signal for Message B (for example, an RRC signal).

[0169] Furthermore, base station 100 does not need to notify PUCCH resources by PDCCH (in other words, DCI), and therefore PDCCH overhead can be reduced.

[0170] (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.

[0171] In this embodiment, terminal 200 transmits an ACK / NACK signal for Message B on an uplink data channel (for example, PUSCH).

[0172] At this time, base station 100 notifies terminal 200 of the PUSCH resource for transmitting the ACK / NACK signal, for example, by using the UL grant included in the RAR of Message B. Terminal 200 determines the PUSCH resource for transmitting the ACK / NACK signal for Message B (for example, an RRC signal), based on the UL grant included in the RAR of Message B addressed to terminal 200, for example.

[0173] For example, in operation example 2 of the two-step random access procedure in embodiment 1 (see, for example, FIG. 8), when base station 100 detects and correctly decodes Message A, it transmits Message B. At this time, Message B includes a message including RAR and a UE-ID for identifying terminal 200.

[0174] In the present embodiment, when base station 100 detects and correctly decodes Message A, it notifies, in an UL grant included in the RAR, uplink resources (e.g., PUSCH resources) for transmitting an ACK / NACK signal for Message B (e.g., an RRC signal). Terminal 200 receives Message B including information addressed to terminal 200, and, if the UE-ID included in Message B matches the UE-ID transmitted in Message A and if Message B includes a MAC PDU including an RRC signal addressed to terminal 200, it decodes the MAC PDU and transmits the decoding result (e.g., an ACK / NACK signal) to base station 100 in the PUSCH resources notified in the UL grant.

[0175] For example, in the example shown in Fig. 8, base station 100 (gNB) detects Preamble #1 of Message A transmitted from UE #A (detection result: ○) and correctly decodes the PUSCH (decoding result: ○). Therefore, base station 100 sets, in Message B, a PUSCH resource for transmitting an ACK / NACK signal for Message B in the UL grant included in the RAR for UE #A. UE #A transmits the ACK / NACK signal for Message B based on the PUSCH resource indicated in the UL grant included in the RAR for UE #A included in Message B.

[0176] Furthermore, in operation example 2 of the two-step random access procedure in embodiment 1 (see, for example, FIG. 8), base station 100 detects the RACH preamble of Message A, and also transmits Message B if it is unable to correctly decode the data portion. At this time, Message B includes an RAR. RAR may include, for example, information regarding a request for retransmission of the data portion to terminal 200 that transmitted the corresponding RACH preamble, and information regarding resources used in the uplink by terminal 200 (UL grant).

[0177] In the present embodiment, for example, when base station 100 detects the RACH preamble of Message A (Message A of UE#B in FIG. 8) and is unable to correctly decode the data portion, it notifies, in an UL grant included in an RAR, of uplink resources (e.g., PUSCH resources) for retransmitting the data portion of Message A (e.g., PUSCH). Terminal 200 (UE#B in FIG. 8) retransmits the data portion of Message A (e.g., PUSCH) based on the PUSCH resources indicated in the UL grant included in the RAR of Message B addressed to terminal 200.

[0178] In this embodiment, for example, in FIG. 6, the processes of transmitting and acquiring information about PUCCH resources for transmitting ACK / NACK for Message B (for example, the processes in ST101 and ST102) are not necessary.

[0179] Furthermore, as a method for mapping an ACK / NACK signal in a PUSCH, for example, one of the following two methods may be applied.

[0180] The first method is to map the ACK / NACK signal to the PUSCH in the same way as the data portion, as in the UL Shared Channel (UL-SCH). In this case, the ACK / NACK signal is transmitted according to the MCS indicated by the UL grant.

[0181] The second method is to map the ACK / NACK signal to the PUSCH by multiplexing UCI (Uplink Control Information) onto the PUSCH when there is no UL-SCH in Release 15 NR (see, for example, Non-Patent Documents 2 and 3). In this case, the ACK / NACK signal may be transmitted in accordance with an MCS lower than the MCS indicated by the UL grant.

[0182] According to the present embodiment, base station 100 notifies, by an UL grant included in the RAR of Message B, of a PUSCH resource for transmitting an ACK / NACK signal for Message B. In other words, base station 100 can configure (in other words, schedule) a PUSCH resource for each terminal 200 in an UL grant included in the RAR for each terminal 200 of Message B.

[0183] This allows terminal 200 to individually determine the PUSCH resource for transmitting an ACK / NACK signal for Message B transmitted via groupcast (in other words, a signal addressed to multiple terminals 200), based on the UL grant set for each terminal 200. This makes it possible to reduce collisions of PUSCH resources between terminals 200 when transmitting an ACK / NACK signal for Message B (for example, an RRC signal).

[0184] Furthermore, base station 100 does not need to notify PUSCH resources by PDCCH (in other words, DCI), and therefore PDCCH overhead can be reduced.

[0185] Furthermore, in the present embodiment, the UL grant included in the RAR of Message B indicates a PUSCH resource for retransmitting Message A (for example, a PUSCH) or a PUSCH resource for transmitting an ACK / NACK signal for Message B. In other words, in the present embodiment, the resource indicated in the RAR of Message B is a PUSCH resource, regardless of the detection and decoding results of Message A in base station 100. Therefore, according to the present embodiment, the information indicated in the UL grant of RAR does not need to be changed depending on the decoding result of Message A in base station 100, and therefore the configuration of the RAR can be simplified.

[0186] An embodiment of the present disclosure has been described above.

[0187] In the above-described embodiments, the case has been described where terminal 200 transmits an ACK / NACK signal (ACK or NACK) for Message B. However, terminal 200 may transmit a NACK to base station 100 if it fails to decode Message B, and may not transmit an ACK to base station 100 if it succeeds in decoding Message B, for example.

[0188] For example, terminal 200 determines that the random access operation has been completed correctly if it correctly decodes the PDCCH that schedules Message B and correctly decodes the MAC PDU included in Message B. Furthermore, terminal 200 does not transmit an ACK to base station 100.

[0189] On the other hand, if terminal 200 correctly decodes the PDCCH that schedules Message B but fails to correctly decode the MAC PDU included in Message B, it transmits a NACK to base station 100 to request that Message B be retransmitted.

[0190] Furthermore, terminal 200 may start a timer from the timing of transmitting a NACK. If base station 100 successfully receives the NACK transmitted by terminal 200, it retransmits Message B. On the other hand, if base station 100 fails to receive the NACK transmitted by terminal 200, it determines that terminal 200 has successfully received Message B and is unable to retransmit Message B. In this case, if the timer started from the timing of transmitting a NACK exceeds a certain period, terminal 200 performs the RACH operation again.

[0191] In this way, terminal 200 does not transmit ACK, so that the overhead of uplink resources can be reduced, and the power consumption of terminal 200 can be reduced.

[0192] Furthermore, in each of the above-described embodiments, terminal 200 may transmit an ACK to base station 100 if it succeeds in decoding Message B, and may not transmit a NACK to base station 100 if it fails to decode Message B.

[0193] For example, if Message B includes a MAC PDU including an RAR and a MAC PDU including a message (e.g., Contention resolution MAC CE) including identification information for identifying a terminal (e.g., UE-ID), and if terminal 200 fails to decode Message B, it cannot determine whether Message B that it attempted to decode is addressed to its own terminal. Therefore, terminal 200 does not need to transmit a NACK to base station 100.

[0194] 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, etc. is also a possibility.

[0195] 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.

[0196] 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.

[0197] Communications include data communications via cellular systems, wireless LAN systems, communications satellite systems, etc., as well as data communications via combinations of these.

[0198] A communications device 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 device.

[0199] 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.

[0200] A terminal according to one embodiment of the present disclosure includes a control circuit that determines resources to be used for transmitting response signals to downlink signals intended for multiple terminals based on parameters that are set for each of the multiple terminals, and a transmission circuit that transmits the response signals in the resources.

[0201] In one embodiment of the present disclosure, the control circuit determines the resource based on a value notified by control information related to the downlink signal, a resource to which the control information is assigned, and the parameter.

[0202] In one embodiment of the present disclosure, the downlink signal includes information regarding a response to a random access signal transmitted by each of the plurality of terminals, and the parameter is included in the information regarding the response.

[0203] In one embodiment of the present disclosure, the downlink signal includes information regarding responses to random access signals transmitted by each of the multiple terminals, and the parameter indicates a value associated with information included in the random access signal that identifies each of the multiple terminals.

[0204] In one embodiment of the present disclosure, the downlink signal includes information regarding responses to random access signals transmitted by each of the multiple terminals, and the parameter indicates a value associated with the arrangement order of the information regarding the responses corresponding to each of the multiple terminals in the downlink signal.

[0205] In one embodiment of the present disclosure, the downlink signal includes information regarding responses to random access signals transmitted by each of the multiple terminals, and the parameter indicates a value associated with a preamble number used in the random access signal.

[0206] In one embodiment of the present disclosure, the downlink signal includes information regarding a response to a random access signal including a preamble portion and a data portion, which is transmitted by each of the multiple terminals, and the parameter indicates a value associated with a port number of a reference signal used in the data portion.

[0207] In one embodiment of the present disclosure, the downlink signal includes information regarding a response to a random access signal transmitted by each of the plurality of terminals, and the parameter is uplink resource allocation information included in the information regarding the response.

[0208] In one embodiment of the present disclosure, the resource is an uplink control resource.

[0209] In one embodiment of the present disclosure, the resource is an uplink data resource.

[0210] A transmission method according to one embodiment of the present disclosure determines resources to be used for transmitting response signals to downlink signals intended for multiple terminals based on parameters set for each of the multiple terminals, and transmits the response signals using the resources.

[0211] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2019-061499, filed on March 27, 2019, are incorporated herein by reference in their entirety. [Industrial Applicability]

[0212] An embodiment of the present disclosure is useful in a mobile communication system. [Explanation of symbols]

[0213] 100 base stations 101,209 Control unit 102 Data Generation Unit 103,107,110,212,214 Encoding section 104 Retransmission control section 105, 108, 111, 213, 215 Modulation section 106 Upper control signal generation unit 109 Downstream control signal generator 112,216 Signal Allocation Section 113,217 IFFT section 114,218 Transmitter 115,201 antennas 116,202 Receiver 117,203 FFT section 118,204 Extraction part 119 Detector 120,205 Demodulation section 121,206,208 Decoding section 200 devices 207 Downstream control signal demodulation unit 210 PRACH preamble generation unit 211 ACK / NACK generation section< / option>

Claims

1. a transmission circuit for transmitting a message B which is a transmission response to the random access signal; a receiving circuit for receiving a response signal to the message B using a PUCCH (Physical Uplink Control Channel) resource determined based on a first parameter included in the message B; the receiving circuit receives message 3 using the resource notified in message B when message B requests retransmission of the data portion of the random access signal; Base station.

2. the PUCCH resource is determined based on the first parameter without using a bit of a physical downlink control channel and a control channel element number; The base station of claim 1 .

3. The PUCCH resource is determined from a plurality of resources based on the first parameter, and the plurality of resources are notified by higher layer signaling. The base station of claim 1 .

4. The message B includes transmission timing information used to transmit the response signal. The base station of claim 1 .

5. If the identification information of the terminal is included in the message B, it is determined that the random access procedure is completed. The base station of claim 1 .

6. If the message B requests retransmission of the data portion of the random access signal, the message B does not include the identification information of the terminal; The base station of claim 1 .

7. The message B does not include control information for one or more terminals for which the preamble portion of the random access signal is not detected by the base station. The base station of claim 1 .

8. the random access signal includes a preamble portion and a data portion; The base station of claim 1 .

9. The base station is Transmitting a message B in response to the transmission of the random access signal; receiving a response signal to the message B on a PUCCH (Physical Uplink Control Channel) resource determined based on a first parameter included in the message B; If the message B requests retransmission of the data portion of the random access signal, receive the message 3 using the resource notified in the message B. Communication method.

10. the PUCCH resource is determined based on the first parameter without using a bit of a physical downlink control channel and a control channel element number; The communication method according to claim 9.

11. determining the PUCCH resource from a plurality of resources based on the first parameter, and notifying the plurality of resources by higher layer signaling; The communication method according to claim 9.

12. The message B includes transmission timing information used to transmit the response signal. The communication method according to claim 9.

13. If the identification information of the terminal is included in the message B, it is determined that the random access procedure is completed. The communication method according to claim 10.

14. If the message B requests retransmission of the data portion of the random access signal, the identification information of the terminal is not included in the message B; The communication method according to claim 10.

15. The message B does not include control information for one or more terminals for which the preamble portion of the random access signal is not detected by the base station. The communication method according to claim 9.

16. the random access signal includes a preamble portion and a data portion; The communication method according to claim 9.

17. a process of transmitting a message B which is a response to the transmission of the random access signal; receiving a response signal to the message B on a physical uplink control channel (PUCCH) resource determined based on a first parameter included in the message B; receiving a message 3 using resources notified in the message B if the message B requests retransmission of the data portion of the random access signal; Controlling Integrated circuit.

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