Patent ID: 8526310

Claim:
A method comprising: a) receiving, by a wireless device, at least one control message from a base station, said at least one control message causing in said wireless device: i) configuration of a plurality of cells comprising a primary cell and at least one secondary cell; ii) assignment of each of said at least one secondary cell to a cell group in a plurality of cell groups, said plurality of cell groups comprising: (1) a primary cell group comprising a first subset of said plurality of cells, said first subset comprising said primary cell, uplink transmissions by said wireless device in said primary cell group employing a first synchronization signal transmitted on said primary cell as a primary timing reference; and (2) a secondary cell group comprising a second subset of said at least one secondary cell; and iii) configuration of transmissions of sounding reference signals on a secondary cell in said secondary cell group; b) receiving, by said wireless device, an activation command to activate said secondary cell in said wireless device; c) receiving, by said wireless device, a control command configured to cause transmission of a random access preamble on random access resources of one of said at least one secondary cell in said second subset; d) receiving, by said wireless device, a random access response, said random access response comprising a timing advance command for said secondary cell group; e) transmitting, by said wireless device, one or more of said sounding reference signals on said secondary cell after applying said timing advance command to said secondary cell group, said wireless device configured to not transmit any of said sounding reference signals on said secondary cell during a period: i) between receiving said activation command and applying said timing advance command; or ii) when said secondary cell is inactive; or iii) when a time alignment timer for said secondary cell group is not running; and f) dropping, by said wireless device, transmission of a sounding reference signal in said sounding reference signals in a subframe of said secondary cell when said wireless device is power limited in said subframe.