Device to-device communications apparatus and methods
A node of a radio access network ( 22 ) communicates with a wireless terminal ( 26 1 ) over a radio interface and sends to the wireless terminal ( 26 1 ) an indication ( 62 ) which specifies, for device-to-device (D2D) communications with another wireless terminal ( 26 2 ), whether the wireless terminal ( 26 1 ) is to use network-allocated radio resources or radio resources which are selected by the wireless terminal.
1. A method in a wireless terminal which communicates with a node of a radio access network over a radio interface, the method comprising:
using receiver circuitry to receive from the node an indication which specifies, for device-to-device (D2D) communications with another wireless terminal, which of
(1) network-allocated radio resources or
(2) radio resources selected by the wireless terminal are to be used by the wireless terminal; and
using processor circuitry of the wireless terminal:
to use radio resources for the device-to-device (D2D) communications with the another wireless terminal in accordance with the indication;
to perform a cell selection/reselection operation; and
to set one frequency to a highest priority frequency with respect to the cell selection/reselection operation when the wireless terminal is performing:
(i) device-to-device (D2D) communications in a state where the wireless terminal camps on the one frequency; and
(ii) the cell selection/reselection operation.
2. The method of claim 1 , further comprising receiving the indication in broadcasted system information.
3. The method of claim 1 , wherein the radio resources which are selected by the wireless terminal comprise a pool of radio resources, and wherein the method further comprises the processor circuitry of the wireless terminal selecting from which pool a radio resource for actual use in the device-to-device (D2D) communications.
4. The method of claim 1 , further comprising, when the indication specifies that the wireless terminal is to use network-allocated radio resources:
the wireless terminal sending a scheduling request to the node; and
in response to the scheduling request, the wireless terminal receiving a grant of the network-allocated radio resources to the wireless terminal in a subframe.
5. The method of claim 1 , further comprising the wireless terminal receiving an indication to use the radio resources which are selected by the wireless terminal when the wireless terminal is in a radio resource control (RRC) Idle state.
6. The method of claim 1 , further comprising the wireless terminal receiving an indication to use the network-allocated radio resources when the wireless terminal is in a radio resource control (RRC) Connected state.
7. A wireless terminal which communicates with a node of a radio access network over a radio interface, the wireless terminal comprising:
receiver circuitry configured to receive from the node an indication which specifies, for device-to-device (D2D) communications with another wireless terminal which of
(1) network-allocated radio resources or
(2) radio resources selected by the wireless terminal are to be used by the wireless terminal; and
processor circuitry configured to use radio resources for the device-to-device (D2D) communications with the another wireless terminal in accordance with the indication;
to perform a cell selection/reselection operation; and
to set one frequency to a highest priority frequency with respect to the cell selection/reselection operation when the wireless terminal is performing:
(i) device-to-device (D2D) communications in a state where the wireless terminal camps on the one frequency; and
(ii) the cell selection/reselection operation.
8. The wireless terminal of claim 7 , wherein the receiver circuitry is configured to receive the indication in broadcasted system information.
9. The wireless terminal of claim 7 , further comprising a memory wherein is stored a pool of resources which are selected by the wireless terminal, and wherein the processor circuitry is further configured to select from the pool radio resources for actual use in the device-to-device (D2D) communications.
10. The wireless terminal of claim 7 , wherein wireless terminal further comprises transmitter circuitry, and wherein when the indication specifies that the wireless terminal is to use network-allocated radio resources,
the transmitter circuitry is configured to transmit a scheduling request to the node; and
the receiver circuitry is further configured to receive a grant of the network-allocated radio resources from the node in a subframe.
11. The wireless terminal of claim 7 , wherein the processor circuitry is further configured to use the resources which are selected by the wireless terminal when the wireless terminal is in a radio resource control (RRC) Idle state.
12. The wireless terminal of claim 7 , wherein the processor circuitry is further configured to use the network-allocated resources when the wireless terminal is in a radio resource control (RRC) Connected state.