Mobile communications network

A mobile terminal for operation in a communications network, wherein the mobile terminal comprises:

• a first transceiver for exchanging signals with a serving base station;
• a second transceiver for exchanging signals with a second base station;
• and
• a processor configured to:
• receive a first broadcast or multicast signal from the serving base station and a second signal from a second base station;
• determine an indication of a length of a first cyclic prefix of the first broadcast or multicast signal and an indication of a length of a second cyclic prefix of the second signal;
• and
• where the mobile terminal determines that the lengths of the first and second cyclic prefixes are different, initiate a switch in communication between the mobile terminal and the serving base station to unicast.

A method comprising, at a base station:

• serving a mobile terminal over broadcast or multicast;
• sending to the mobile terminal a broadcast or multicast signal comprising a first cyclic prefix with a first length;
• receiving from the mobile terminal an indication that the mobile terminal has detected a second cyclic prefix with a second length;
• and
• switching communicating with the mobile terminal from broadcast or multicast to unicast.

A base station for a mobile communications network, wherein the base station comprises:

• a transmitter configured to serve a mobile terminal using broadcast or multicast and to transmit a broadcast or multicast signal to the mobile terminal, wherein the transmitted broadcast or multicast signal comprises a first cyclic prefix with a first length;
• a receiver configured to receive signals from the mobile terminal;
• and
• a processor configured to:
• receive from the mobile terminal an indication that the mobile terminal has detected a second cyclic prefix with a second length;
• and
• switch communication with the mobile terminal from broadcast or multicast to unicast.