Radio Access for a Wireless Device and Base Station

1 . A method comprising:

a) receiving, by a wireless device to communicate employing a plurality of cells, at least one control message from a base station, said at least one control message causing in said wireless device:

i) configuration of a primary cell and at least one secondary cell in said plurality of cells; and

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) at least one secondary cell group, a secondary cell group in said at least one secondary cell group comprising a second subset of said at least one secondary cell, uplink transmissions in said secondary cell group employing a second synchronization signal on an activated secondary cell in said secondary cell group as a secondary timing reference;

b) transmitting, by said wireless device, a random access preamble on random access resources of a first secondary cell in said at least one secondary cell in response to receiving a control command;

c) receiving, by said wireless device, a random access response on said primary cell of said primary cell group, said random access response comprising:

i) a timing advance command;

ii) an uplink grant; and

iii) a preamble identifier identifying said random access preamble;

d) applying, by said wireless device, said timing advance command only to uplink transmission timing of a first secondary cell group comprising said first secondary cell; and

e) transmitting, by said wireless device, uplink data on said first secondary cell in radio resources identified in said uplink grant.

2 . The method of claim 1 , wherein said random access response:

a) does not comprise an index identifying said first secondary cell group; and

b) does not comprise an index identifying said first secondary cell.

3 . The method of claim 1 , wherein an identifier of said random access response depends, at least in part, on:

a) a subframe index associated with a subframe in which said random access preamble is transmitted; and

b) a frequency index associated with a frequency offset in said random access resources employed for said random access preamble transmission.

4 . The method of claim 3 , further comprising said wireless device monitoring a downlink control channel on said primary cell for random access responses identified by said identifier.

5 . The method of claim 4 , wherein said monitoring is performed within a time frame, said time frame:

a) starting at a subframe that contains the end of transmission of said random access preamble plus k subframes, k being an integer greater than one; and

b) having a duration smaller than or equal to a random access response window.

6 . The method of claim 1 , wherein said first secondary cell is said activated secondary cell.

7 . The method of claim 1 , further comprising, receiving by said wireless device, an activation command to activate said first secondary cell in said wireless device prior to receiving said control command.

8 . The method of claim 1 , wherein said control command comprises an index identifying said first secondary cell only if said control command is not transmitted on said first secondary cell.

9 . The method of claim 1 , further comprising transmitting, by said wireless device, said random access preamble in said random access resources of said first secondary cell.

10 . A wireless device comprising:

a) one or more communication interfaces;

b) one or more processors; and

c) memory storing instructions that, when executed, cause said wireless device to:

i) receive at least one control message from a base station, said at least one control message causing in said wireless device:

(1) configuration of a plurality of cells comprising a primary cell and at least one secondary cell; and

(2) 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:

(a) a primary cell group comprising a first subset of said plurality of cells, said first subset comprising said primary cell; and

(b) at least one secondary cell group, a secondary cell group in said at least one secondary cell group comprising a second subset of said at least one secondary cell;

ii) transmit a random access preamble on random access resources of a first secondary cell in said at least one secondary cell in response to receiving a control command;

iii) receive a random access response corresponding to said random access preamble transmission on said primary cell of said primary cell group, said random access response comprising:

(1) a timing advance command; and

(2) an uplink grant;

iv) apply said timing advance command only to uplink transmission timing of a first secondary cell group comprising said first secondary cell; and

v) transmit uplink data on said first secondary cell in radio resources identified in said uplink grant.

11 . The wireless device of claim 10 , wherein said random access response corresponds to said random access preamble transmission employing:

a) an identifier of said random access response; and

b) a preamble identifier identifying said random access preamble.

12 . The wireless device of claim 10 , wherein said control command is received on a scheduling cell of said first secondary cell.

13 . The wireless device of claim 10 , wherein said control command comprises:

a) a mask index; and

b) a preamble identifier identifying said random access preamble.

14 . The wireless device of claim 10 , wherein said wireless device is assigned, by said configuration, a plurality of media access control dedicated parameters comprising a plurality of time alignment timer values, each time alignment timer value being associated with a unique cell group in said wireless device.

15 . A base station comprising:

a) one or more communication interfaces;

b) one or more processors; and

c) memory storing instructions that, when executed, cause said base station to:

i) transmit at least one control message to a wireless device, said at least one control message configured to cause in said wireless device:

(1) configuration of a plurality of cells comprising a primary cell and at least one secondary cell; and

(2) 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:

(a) a primary cell group comprising a first subset of said plurality of cells, said first subset comprising said primary cell; and

(b) at least one secondary cell group, a secondary cell group in said at least one secondary cell group comprising a second subset of said at least one secondary cell;

ii) transmit a control command configured to cause transmission of a random access preamble on random access resources of a first secondary cell in said at least one secondary cell;

iii) transmit a random access response corresponding to said random access preamble reception on said primary cell of said primary cell group, said random access response comprising:

(1) a timing advance command; and

(2) an uplink grant; and

iv) receive uplink data from said wireless device on said first secondary cell in radio resources identified in said uplink grant; and

wherein said timing advance command configured to cause substantial alignment of reception timing of uplink signals in frames and subframes of a first secondary cell group comprising said first secondary cell.

16 . The base station of claim 15 , wherein said random access response:

a) does not comprise an index identifying said first secondary cell group; and

b) does not comprise an index identifying said first secondary cell.

17 . The base station of claim 15 , wherein an identifier of said random access response depends, at least in part, on:

a) a subframe index associated with a subframe in which said random access preamble is transmitted; and

b) a frequency index associated with a frequency offset in said random access resources employed for said random access preamble transmission.

18 . The base station of claim 15 , wherein said random access response corresponds to said random access preamble employs:

a) an identifier of said random access response; and

b) a preamble identifier identifying said random access preamble.

19 . The base station of claim 15 , wherein said at least one control message is configured to further cause in said wireless device configuration of a time alignment timer for each of said plurality of cell groups, said time alignment timer starting or restarting in response to said wireless device receiving a timing advance command to adjust uplink transmission timing of a commanded cell group in said plurality of cell groups.

20 . The base station of claim 15 , wherein said at least one control message comprises a plurality of common parameters for said first secondary cell, said plurality of common parameters comprising:

a) a plurality of random access resource parameters identifying said random access resources; and

b) a plurality of power control parameters.