Mobile communication system, base station, user terminal and processor
A mobile communication system according to the present invention supports cellular communication in which a data path passes through a core network and D2D communication that is direct device-to-device communication in which a data path does not pass through the core network. The mobile communication system has a user terminal that performs a process of discovering a partner terminal in the D2D communication or performs the D2D communication. A plurality of radio resources that are the time-frequency resources that can be used for the process of discovering or the D2D communication consist of radio resources associated with transmission power used for the process of discovering or the D2D communication. The user terminal performs the process of discovering or the D2D communication on the basis of the transmission power associated with the radio resource used by the user terminal.
1. A mobile communication method, comprising:
including, by a base station, a plurality of information sets into a message, wherein the plurality of information sets are used to transmit a discovery signal in a discovery procedure;
transmitting the message from the base station to a user terminal in a unicast manner; and
transmitting, from the user terminal to another user terminal, the discovery signal for discovering the another user terminal in the discovery procedure, wherein
each information set of the plurality of information sets includes radio resources used for a transmission of the discovery signal, power information for controlling transmission power of the discovery signal, and a threshold value associated with the radio resources, wherein the threshold value is an upper limit value and a lower limit value compared with a predetermined value calculated by use of a received power of a reference signal received from the base station, and
the mobile communication method further comprises:
receiving the reference signal from the base station to the user terminal,
comparing, by the user terminal, the predetermined value with the threshold value,
selecting, by the user terminal, an information set from among the plurality of information sets in response to the predetermined value being between the upper limit value and the lower limit value included in the selected information, and
directly transmitting, from the user terminal to the another user terminal, the discovery signal with transmission power based on power information included in the selected information set by use of radio resources included in the selected information set.
2. A base station, comprising:
a controller, that includes a processor coupled to a memory, the controller configured to include a plurality of information sets into a message, wherein the plurality of information sets are used to transmit a discovery signal in a discovery procedure; and
a transmitter configured to transmit the message to a user terminal in a unicast manner, wherein
each information set of the plurality of information sets includes radio resources used for a transmission of the discovery signal, power information for controlling transmission power of the discovery signal, and a threshold value associated with the radio resources, wherein the threshold value is an upper limit value and a lower limit value compared with a predetermined value calculated by use of a received power of a reference signal received from the base station in the user terminal, and
the threshold value is used for a comparison of the threshold value with the predetermined value, in order for the user terminal to select an information set from among the plurality of information sets in response to the predetermined value being between the upper limit value and the lower limit value included in the selected information.
3. A user terminal, comprising:
a controller that includes a processor coupled to a memory,
a receiver configured to receive a message transmitted from a base station in a unicast manner, and
a transmitter configured to transmit a discovery signal for discovering another user terminal in a discovery procedure, wherein
the message includes a plurality of information sets used to transmit the discovery signal in the discovery procedure,
each information set of the plurality of information sets includes radio resources used for a transmission of the discovery signal, power information for controlling transmission power of the discovery signal, and a threshold value associated with the radio resources, wherein the threshold value is an upper limit value and a lower limit value compared with a predetermined value calculated by use of a received power of a reference signal received from the base station,
the receiver is configured to receive the reference signal from the base station,
the controller is configured to:
compare the predetermined value with the threshold value, and
select an information set from among the plurality of information sets, in response to the predetermined value being between the upper limit value and the lower limit value included in the selected information, and
the transmitter is configured to directly transmit the discovery signal to the another user terminal with transmission power based on power information included in the selected information set by use of radio resources included in the selected information set.
4. A processor for controlling a base station, the processor coupled to a memory and configured to:
include a plurality of information sets into a message, wherein the plurality of information sets are used to transmit a discovery signal in a discovery procedure; and
transmit the message to a user terminal in a unicast manner, wherein
each information set of the plurality of information sets includes radio resources used for a transmission of the discovery signal, power information for controlling transmission power of the discovery signal, and a threshold value associated with the radio resources, wherein the threshold value is an upper limit value and a lower limit value compared with a predetermined value calculated by use of a received power of a reference signal received from the base station in the user terminal, and
the threshold value is used for a comparison of the threshold value with the predetermined value, in order for the user terminal to select an information set from among the plurality of information sets in response to the predetermined value being between the upper limit value and the lower limit value included in the selected information.
5. A processor for controlling a user terminal, the processor coupled to a memory and configured to:
receive a message transmitted from a base station in a unicast manner; and
transmit a discovery signal for discovering another user terminal in a discovery procedure, wherein
the message includes a plurality information sets used to transmit the discovery signal in the discovery procedure,
each information set of the plurality of information sets includes radio resources used for a transmission of the discovery signal, power information for controlling transmission power of the discovery signal, and a threshold value associated with the radio resources, wherein the threshold value is an upper limit value and a lower limit value compared with a predetermined value calculated by use of a received power of a reference signal received from the base station,
the processor is further configured to:
receive the reference signal from the base station,
compare the predetermined value with the threshold value,
select an information set from among the plurality of information sets, in response to the predetermined value being between the upper limit value and the lower limit value included in the selected information, and
directly transmit the discovery signal to the another user terminal with transmission power based on power information included in the selected information set by use of radio resources included in the selected information set.