Terminal device, base station device, communication method, and integrated circuit
Provided is technology relating to: a terminal device, a base station device, a communication system, a communication method, and an integrated circuit capable of efficiently performing a radio resource control procedure. The terminal device is provided with a first sublayer and a second sublayer that is a lower sublayer than the first sublayer. The first sublayer creates an RRC message corresponding to an RRC procedure and starts a timer relating to the RRC procedure on the basis of coverage level information. The second sublayer executes a random access procedure relating to the RRC procedure on a serving cell, determines the coverage level information in the random access procedure, and selects a random access preamble group on the basis of the determined coverage level information.
1. A terminal device communicating with a base station device, the terminal device comprising:
a first sublayer; and
a second sublayer being a lower sublayer than the first sublayer,
the first sublayer acquiring, from the base station device, a common radio resource configuration for all terminal devices, the common radio resource configuration including:
first information for a timer T300 used in a Radio Resource Control (RRC) connection establishment procedure on a serving cell, the first information including a first value range of the timer for the terminal device that supports coverage enhancement using repetitive transmissions and a second value range of the timer for another terminal device that does not support the coverage enhancement using repetitive transmissions, the first value range always exceeding the second value range, and the second value range is not more than 2000 ms;
second information indicating mapping between values of levels and numbers of repetitions; and
third information indicating mapping between the values of levels and random access preamble groups,
the first sublayer starting the timer and creating an RRC connection request message corresponding to the RRC connection establishment procedure, and
the second sublayer determining one of the values of the levels that corresponds to one of the numbers of repetitions in a random access procedure related to the RRC connection establishment procedure, selecting one of the random access preamble groups that corresponds to the determined one of the values of the levels, and selecting a random access preamble from the selected one of the random access preamble groups.
2. The terminal device according to claim 1 ,
wherein when determining that the random access procedure has succeeded, the second sublayer indicates the determined one of the values of the levels to the first sublayer.
3. The terminal device according to claim 1 ,
wherein the second sublayer indicates, to the first sublayer, one of the values of the levels indicated by a random access response received in the random access procedure.
4. The terminal device according to claim 1 ,
wherein the first sublayer is an RRC sublayer and the second sublayer is a medium access control (MAC) sublayer.
5. The terminal device according to claim 1 , wherein
the second sublayer determines the one of the values of the levels based on (i) system information included in the common radio resource configuration and (ii) measured reception quality of a downlink reference signal.
6. A base station device communicating with terminal devices, the base station device comprising:
a processor; and
memory in electronic communication with the processor, wherein instructions stored in the memory are executable to:
transmit, to the terminal devices, a common radio resource configuration for the terminal devices, the common radio resource configuration including:
first information for a timer T300 used in a Radio Resource Control (RRC) connection establishment procedure, the first information including a first value range of the timer for one of the terminal devices that supports coverage enhancement using repetitive transmissions and a second value range of the timer for another one of the terminal devices that does not support the coverage enhancement using repetitive transmissions, the first value range always exceeding the second value range, and the second value range is not more than 2000 ms;
second information indicating mapping between values of levels and numbers of repetitions; and
third information indicating mapping between the values of levels and random access preamble groups,
receive, from the terminal devices, random access preambles corresponding to a random access procedure related to the RRC connection establishment procedure, one of the terminal devices being configured to determine one of the values of the levels that corresponds to one of the numbers of repetitions in the random access procedure, select one of the random access preamble groups that corresponds to the determined one of the values of the levels, and select one of the random access preambles from the selected one of the random access preamble groups, and
receive, from the terminal devices, RRC connection request messages corresponding to the RRC connection establishment procedure, each of the terminal devices being configured to start the timer and transmit one of the RRC connection request messages.
7. A communication method of a terminal device communicating with a base station device, the terminal device including a first sublayer and a second sublayer being a lower sublayer than the first sublayer,
the communication method comprising:
in the first sublayer, acquiring, from the base station device, a common radio resource configuration for all terminal devices, the common radio resource configuration including:
first information for a timer T300 used in a Radio Resource Control (RRC) connection establishment procedure on a serving cell, the first information including a first value range of the timer for the terminal device that supports coverage enhancement using repetitive transmissions and a second value range of the timer for another terminal device that does not support the coverage enhancement using repetitive transmissions, the first value range always exceeding the second value range, and the second value range is not more than 2000 ms;
second information indicating mapping between values of levels and numbers of repetitions; and
third information indicating mapping between the values of levels and random access preamble groups,
in the first sublayer, starting the timer and creating an RRC connection request message corresponding to the RRC connection establishment procedure, and
in the second sublayer, determining one of the values of the levels that corresponds to one of the numbers of repetitions in a random access procedure related to the RRC connection establishment procedure, selecting one of the random access preamble groups that corresponds to the determined one of the values of the levels, and selecting a random access preamble from the selected one of the random access preamble groups.
8. The communication method according to claim 7 , further comprising
indicating the determined one of the values of the levels to the first sublayer when the second sublayer determines that the random access procedure has succeeded.
9. The communication method according to claim 7 , wherein
in the second sublayer, determining the one of the values of the levels is based on (i) system information included in the common radio resource configuration and (ii) measured reception quality of a downlink reference signal.
10. A communication method of a base station device communicating with terminal devices, the communication method comprising:
transmitting, to the terminal devices, a common radio resource configuration for the terminal devices, the common radio resource configuration including:
first information for a timer T300 used in a Radio Resource Control (RRC) connection establishment procedure, the first information including a first value range of the timer for one of the terminal devices that supports coverage enhancement using repetitive transmissions and a second value range of the timer for another one of the terminal devices that does not support the coverage enhancement using repetitive transmissions, the first value range always exceeding the second value range, and the second value range is not more than 2000 ms;
second information indicating mapping between values of levels and numbers of repetitions; and
third information indicating mapping between the values of levels and random access preamble groups,
receiving, from the terminal devices, random access preambles corresponding to a random access procedure related to the RRC connection establishment procedure, one of the terminal devices being configured to determine one of the values of the levels that corresponds to one of the numbers of repetitions in the random access procedure, select one of the random access preamble groups that corresponds to the determined one of the values of the levels, and select one of the random access preambles from the selected one of the random access preamble groups, and
receiving, from the terminal devices, RRC connection request messages corresponding to the RRC connection establishment procedure, each of the terminal devices being configured to start the timer and transmit one of the RRC connection request messages.