| CPC H04W 36/0061 (2013.01) [H04W 36/0072 (2013.01); H04W 74/0833 (2013.01)] | 17 Claims |

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1. A method performed by a first base station, the method comprising:
receiving, in response to a user equipment (UE) not receiving a response to a first random access preamble transmitted from the UE to a second base station, a random access message from the UE;
in response to receiving the random access message, transmitting, to the second base station, a request for sequence number transfer information;
subsequent to transmitting the request for sequence number transfer information, transmitting a random access response message to the UE;
receiving sequence number transfer information from the second base station in response to transmitting the request for the sequence number transfer information; and
transmitting a handover completion message to the second base station in response to receiving the sequence number transfer information.
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