Preamble transmission in a wireless device

1. A method for use by a wireless device, the method comprising:

a) receiving at least one control message from a base station, said at least one control message comprising:

i) configuration parameters of a plurality of cells comprising a primary cell and at least one secondary cell; and

ii) a cell group index for assignment of a secondary cell in 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 received by said wireless device 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, uplink transmissions in said secondary cell group employing a second synchronization signal received by said wireless device on an activated secondary cell in said secondary cell group as a secondary timing reference;

b) receiving a control command causing said wireless device to transmit a random access preamble on random access resources of a secondary cell in said secondary cell group; and

c) transmitting, to said base station, said random access preamble on said random access resources, transmission timing of said random access preamble being determined, at least in part, employing uplink subframe transmission timing of said primary cell.

2. The method of claim 1 , wherein said transmission timing of said random access preamble, at least in part, further employs a synchronization signal received by said wireless device on said secondary cell.

3. The method of claim 1 , wherein said transmission timing of said random access preamble by said wireless device is time aligned with uplink subframe transmission timing of said primary cell.

4. The method of claim 1 , wherein said at least one control message comprises a plurality of random access resource parameters, said plurality of random access resource parameters comprising an index, a frequency offset, and a plurality of sequence parameters.

5. The method of claim 1 , further comprising said at least one control message causing configuration of said random access resources.

6. The method of claim 1 , wherein said at least one control message comprise a plurality of media access control dedicated parameters comprising a plurality of time alignment timer values, each time alignment timer value associated with a unique cell group in said wireless device.

7. 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 comprising:

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

(2) a cell group index for assignment of a secondary cell in 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, uplink transmissions by said wireless device in said primary cell group configured to employ a first synchronization signal received by said wireless device on said primary cell as a primary timing reference; and

(b) a secondary cell group comprising a second subset of said at least one secondary cell, uplink transmissions in said secondary cell group configured to employ a second synchronization signal received by said wireless device on an activated secondary cell in said secondary cell group as a secondary timing reference;

ii) receive a control command configured to cause said wireless device to transmit a random access preamble on random access resources of a secondary cell in said secondary cell group; and

iii) transmit said random access preamble on said random access resources to said base station, transmission timing of said random access preamble determined, at least in part, employing uplink subframe transmission timing of said primary cell.

8. The wireless device of claim 7 , wherein said transmission timing of said random access preamble, at least in part, further employs a synchronization signal received by said wireless device on said secondary cell.

9. The wireless device of claim 7 , wherein transmission timing of said random access preamble by said wireless device is time aligned with uplink frame and subframe transmission timing of said primary cell.

10. The wireless device of claim 7 , wherein said at least one control message comprises a plurality of random access resource parameters, said plurality of random access resource parameters comprising an index, a frequency offset, and a plurality of sequence parameters.

11. The wireless device of claim 7 , wherein said at least one control message comprises configuration parameters of said random access resources.

12. The wireless device of claim 7 , wherein said at least one control message comprise 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.

13. A method for use by a wireless device, the method comprising:

a) receiving, at least one control message from a base station, said at least one control message comprising:

i) configuration parameters of a plurality of cells comprising a primary cell and at least one secondary cell;

ii) a cell group index for assignment of a secondary cell in 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; and

(2) a secondary cell group comprising a second subset of said at least one secondary cell; and

iii) configuration parameter 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 a timing advance of a commanded cell group in said plurality of cell groups;

b) generating, a first updated timing advance by updating a first timing advance of said secondary cell group, employing at least one first timing advance command for said secondary cell group;

c) storing said first updated timing advance upon expiry of an associated time alignment timer of said secondary cell group;

d) receiving, by said wireless device, a control command causing said wireless device to transmit a random access preamble on random access resources of a secondary cell in said secondary cell group; and

e) transmitting, to said base station, said random access preamble on said random access resources, transmission timing of said random access preamble being determined, at least in part, employing said stored first updated timing advance.

14. The method of claim 13 , wherein said first timing advance is approximately equal to a difference between received timing of said secondary timing reference and transmission timing of said uplink signals.

15. The method of claim 13 , wherein a value of said first timing advance is initiated by a value of a timing advance in a random access response for a random access preamble transmitted in said secondary cell group.

16. The method of claim 13 , further comprising setting a value of said first timing advance to zero when said secondary cell group is configured.

17. The method of claim 13 , further comprising releasing said stored first updated timing advance in said wireless device when said secondary cell group is released.

18. The method of claim 13 , wherein said at least one control message comprises a plurality of random access resource parameters, said plurality of random access resource parameters comprising an index, a frequency offset, and a plurality of sequence parameters.

19. The method of claim 13 , wherein said at least one control message comprises configuration parameters of said random access resources.

20. The method of claim 13 , wherein said at least one control message comprises a plurality of media access control dedicated parameters, said plurality of media access control dedicated parameters comprising a plurality of time alignment timer values, each time alignment timer value associated with a unique cell group in said wireless device.