Patent ID: 8619727

Claim:
A method for use in a wireless device, the method comprising: a) receiving at least one message causing configuration of: i) a primary cell and one or more secondary cells; and ii) a plurality of cell groups comprising a primary cell group and a secondary cell group comprising a subset of said one or more secondary cells; b) receiving a control command causing transmission of a random access preamble on random access resources of a reference secondary cell in said secondary cell group; c) receiving a random access response on said primary cell in said primary cell group, said random access response comprising a timing advance command, said timing advance command implicitly corresponding to said secondary cell group and being applicable only to said secondary cell group; d) transmitting first uplink signals in said secondary cell group employing said reference secondary cell used for said random access preamble transmission as a timing reference; e) selecting, autonomously and when a predefined condition is met, a new activated secondary cell in said secondary cell group as said timing reference; and f) transmitting second uplink signals in said secondary cell group employing said new activated secondary cell as said timing reference.