Terminal and communication method
A terminal, with which it is possible to improve the efficiency of a random access process. In a terminal ( 200 ), a control unit ( 209 ) dynamically determines a parameter pertaining to the transmission of a data part out of a random access signal that includes a preamble part and the data part. A transmission unit ( 217 ) notifies the determined parameter to a base station ( 100 ) using the random access signal.
1. A terminal, comprising:
control circuitry, which, in operation, determines a size of a data part of a random access signal including a preamble part and the data part; and
transmission circuitry, which is coupled to the control circuitry and which, in operation, notifies a base station of the determined size using the random access signal, wherein
in response to a transmission of the random access signal, a Medium Access Control layer Protocol Data Unit (MAC PDU) including a response to the random access signal is received, and the MAC PDU includes i) information on a transmission timing of an uplink transmission, and ii) information on uplink resources of an uplink grant, and
the information on uplink resources includes at least one of a frequency resource, a resource amount, or a Modulation and Coding Scheme (MCS), and is used for a transmission of a message 3 in a case of a fallback mode.
2. The terminal according to claim 1 , wherein
the size of the data part is associated with a resource candidate set of the preamble part, and
the preamble part is transmitted using a resource in the resource candidate set.
3. The terminal according to claim 2 , wherein
an association between the size of the data part and the resource candidate set is indicated by a higher layer signaling.
4. The terminal according to claim 2 , wherein
the resource candidate set is different between a 2 step random access type and 4 step random access type.
5. The terminal according to claim 2 , wherein
the resource is determined based on a synchronization signal block (SSB) selected from a plurality of SSBs, and
in a case where there is one or more SSBs with a reference signal received power (RSRP) above a threshold, one of said one or more SSBs is selected as the SSB, and
in a case where there is no SSB with the RSRP above the threshold, any SSB is selected as the SSB.
6. The terminal according to claim 1 , wherein
the preamble part and the data part are multiplexed by a time divisional multiplexing (TDM).
7. The terminal according to claim 1 , wherein
the MAC PDU includes information relating to a contention resolution.
8. The terminal according to claim 7 , wherein
in a case where information included in the random access signal matches with the information relating to the contention resolution included in the response to the random access signal, the terminal considers a random access procedure is successful.
9. The terminal according to claim 1 , wherein
in a case where a response to the random access signal is not received within a determined period, the random access signal is retransmitted.
10. The terminal according to claim 1 , wherein
in response to a transmission of the random access signal, a physical downlink control channel (PDCCH) identified by a Cell-Radio Network Temporary Identifier (C-RNTI) is received.
11. A communication method, comprising:
determining a size of a data part of a random access signal including a preamble part and the data part;
notifying a base station of the determined size using the random access signal; and
in response to a transmission of the random access signal, receiving a Medium Access Control layer Protocol Data Unit (MAC PDU) including a response to the random access signal, wherein
the MAC PDU includes i) information on a transmission timing of an uplink transmission, and ii) information on uplink resources of an uplink grant, and
the information on uplink resources includes at least one of a frequency resource, a resource amount, or a Modulation and Coding Scheme (MCS), and is used for a transmission of a message 3 in a case of a fallback mode.
12. The communication method according to claim 11 , wherein
the size of the data part is associated with a resource candidate set of the preamble part, and
the preamble part is transmitted using a resource in the resource candidate set.
13. The communication method according to claim 12 , wherein
an association between the size of the data part and the resource candidate set is indicated by a higher layer signaling.
14. The communication method according to claim 12 , wherein
the resource candidate set is different between a 2 step random access type and 4 step random access type.
15. The communication method according to claim 12 , wherein
the resource is determined based on a synchronization signal block (SSB) selected from a plurality of SSBs, and
in a case where there is one or more SSBs with a reference signal received power (RSRP) above a threshold, one of said one or more SSBs is selected as the SSB, and
in a case where there is no SSB with the RSRP above the threshold, any SSB is selected as the SSB.
16. The communication method according to claim 11 , wherein
the preamble part and the data part are multiplexed by a time divisional multiplexing (TDM).
17. The communication method according to claim 11 , wherein
the MAC PDU includes information relating to a contention resolution.
18. The communication method according to claim 17 , comprising:
in a case where information included in the random access signal matches with the information relating to the contention resolution included in the response to the random access signal, considering a random access procedure is successful.
19. The communication method according to claim 11 , comprising:
in a case where a response to the random access signal is not received within a determined period, retransmitting the random access signal.
20. The communication method according to claim 11 , comprising:
in response to a transmission of the random access signal, receiving a physical downlink control channel (PDCCH) identified by a Cell-Radio Network Temporary Identifier (C-RNTI).