Telecommunications apparatus and methods

1. A wireless telecommunications system comprising:

a base station; and

a plurality of terminal devices, wherein

a first terminal device is configured to communicate with the base station via a current second terminal device selected from among a plurality of potential second terminal devices,

an exchange of beacon signalling between the first terminal device and respective ones of the potential second terminal devices is triggered when the first terminal device is communicating with the base station via the current second terminal device and a signal quality characteristic associated with communications between the first terminal device and the current second terminal device falls below a predefined threshold,

the beacon signalling is exchanged between the first terminal device and respective ones of the potential second terminal devices for a predetermined period of time,

the current second terminal device is configured to transmit a command to the first terminal device instructing the first terminal device to measure a characteristic of the beacon signalling exchanged between the first terminal device and respective ones of the potential second terminal devices, and

the first terminal device is configured to measure the characteristic of the beacon signalling exchanged between the first terminal device and respective ones of the potential second terminal devices in response to receiving the command from the current second terminal.

2. The wireless telecommunications system of claim 1 , wherein the beacon signalling is transmitted by the first terminal device and received by respective ones of the potential second terminal devices.

3. The wireless telecommunications system of claim 1 , wherein the beacon signalling is transmitted by respective ones of the potential second terminal devices and received by the first terminal device.

4. The wireless telecommunications system of claim 3 , wherein different ones of the potential second terminal devices are configured to begin transmitting their respective beacon signalling at different start times.

5. The wireless telecommunications system of claim 4 , wherein the start time for transmitting beacon signalling for respective ones of the potential second terminal devices is determined from a characteristic of an identifier associated with the respective ones of the potential second terminal devices.

6. The wireless telecommunications system of claim 4 , wherein the start time for transmitting beacon signalling for respective ones of the potential second terminal devices is determined by the respective ones of the potential second terminal devices from signalling received from the base station.

7. The wireless telecommunications system of claim 4 , wherein different start times for different ones of the potential second terminal devices are separated by a period of time that is based on the predetermined period of time for which the beacon signalling is exchanged between the first terminal device and respective ones of the potential second terminal devices.

8. The wireless telecommunications system of claim 1 , wherein an indication of the predetermined period of time for which the beacon signalling is exchanged between the first terminal device and respective ones of the potential second terminal devices is determined from signalling received from the base station.

9. A terminal device for use in a wireless telecommunications system comprising a base station and a plurality of terminal devices, the terminal device comprising:

circuitry configured to

communicate with the base station via a current second terminal device selected from among a plurality of potential second terminal devices;

trigger an exchange of beacon signalling between the terminal device and respective ones of the potential second terminal devices when the terminal device is communicating with the base station via the current second terminal device and a signal quality characteristic associated with communications between the terminal device and the current second terminal device falls below a predefined threshold;

receive, from the current second terminal device, a command instructing the terminal device to measure a characteristic of the beacon signalling exchanged between the terminal device and respective ones of the potential second terminal devices;

measure the characteristic of the beacon signalling exchanged between the terminal device and respective ones of the potential second terminal devices in response to receiving the command from the current second terminal; and

transmit, to the current second terminal device, a measurement report indicating the measured characteristic of the beacon signalling exchanged between the terminal device and the respective ones of the potential second terminal devices.

10. The terminal device of claim 9 , wherein

the circuitry is configured to receive, from the current second terminal device, identification information identifying the potential second terminal devices with which the exchange of beacon signaling is performed.

11. Circuitry for a terminal device for use in a wireless telecommunications system comprising a base station and a plurality of terminal devices, wherein the circuitry is configured to:

communicate with the base station via a current second terminal device selected from among a plurality of potential second terminal devices;

trigger an exchange of beacon signalling between the terminal device and respective ones of the potential second terminal devices when the terminal device is communicating with the base station via the current second terminal device and a signal quality characteristic associated with communications between the terminal device and the current second terminal device falls below a predefined threshold;

receive, from the current second terminal device, a command instructing the terminal device to measure a characteristic of the beacon signalling exchanged between the terminal device and respective ones of the potential second terminal devices;

measure the characteristic of the beacon signalling exchanged between the terminal device and respective ones of the potential second terminal devices in response to receiving the command from the current second terminal; and

transmit, to the current second terminal device, a measurement report indicating the measured characteristic of the beacon signalling exchanged between the terminal device and the respective ones of the potential second terminal devices.

12. A terminal device for use in a wireless telecommunications system comprising a base station and a plurality of terminal devices, the terminal device comprising:

circuitry configured to

communicate with the base station via a current second terminal device selected from among a plurality of potential second terminal devices;

determine to trigger an exchange of beacon signaling between the terminal device and respective ones of the potential second terminal devices when the terminal device is communicating with the base station via the current second terminal device and a signal quality characteristic associated with communications between the first terminal device and the selected second terminal device falls below a predefined threshold;

transmit the beacon signaling for a predetermined period of time based upon determining to trigger the exchange of the beacon signaling between the terminal device and the respective ones of the potential second terminal devices;

receive, from the current second terminal device, a command instructing the terminal device to measure a characteristic of the beacon signalling exchanged between the terminal device and respective ones of the potential second terminal devices;

measure the characteristic of the beacon signalling exchanged between the terminal device and respective ones of the potential second terminal devices in response to receiving the command from the current second terminal; and

transmit, to the current second terminal device, a measurement report indicating the measured characteristic of the beacon signalling exchanged between the terminal device and the respective ones of the potential second terminal devices.

13. The terminal device of claim 12 , wherein

the circuitry is configured to transmit a trigger indication to the base station upon determining to trigger the exchange of the beacon signaling between the terminal device and the respective noes of the potential second terminal devices.

14. The terminal device of claim 13 , wherein

the circuitry is configured to receive, from the base station, an indication of the predetermined period to transmit the beacon signaling in response to the transmitted trigger indication.