Random access preamble transmission

1. A method comprising:

a) receiving by a wireless device at least one message causing:

i) assignment of each of a plurality of secondary cells in a plurality of cells to one of a plurality of cell groups comprising:

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

(2) a secondary cell group comprising a second subset of said plurality of secondary cells; and

ii) configuration of random access resources for at least one secondary cell in said plurality of secondary cells; and

b) receiving by said wireless device a control command being:

i) configurable to cause transmission of a first random access preamble on a secondary cell in said secondary cell group; and

ii) unconfigurable to cause transmission of a second random access preamble on any secondary cell in said primary cell group such that any secondary cell in said primary cell group does not include usable random access resources for said wireless device; and

c) receiving on a primary cell a random access response comprising a timing advance command configured to cause substantial alignment of reception timing of uplink signals in frames and subframes of said secondary cell group at a base station.

2. The method of claim 1 , wherein said primary cell group comprises said primary cell and one or more second secondary cells.

3. The method of claim 1 , wherein said control command is received on a cell employed for scheduling uplink resources for said secondary cell.

4. The method of claim 1 , wherein said control command comprises:

a) a mask index; and

b) a random access preamble identifier.

5. The method of claim 1 , wherein transmission power of said first random access preamble is calculated employing one or more power control parameters.

6. The method of claim 1 , wherein said first random access preamble is transmitted on uplink random access resources identified by:

a) a plurality of random access resource parameters of said secondary cell; and

b) said control command.

7. A wireless device comprising:

one or more communication interfaces;

one or more processors; and

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

i) receive at least one message to cause:

(1) assignment of each of a plurality of secondary cells in a plurality of cells to one of a plurality of cell groups comprising:

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

(b) a secondary cell group comprising a second subset of said plurality of secondary cells; and

(2) configuration of random access resources for at least one secondary cell in said plurality of secondary cells; and

ii) receive a control command being:

(1) configurable to cause transmission of a first random access preamble on a secondary cell in said secondary cell group; and

(2) unconfigurable to cause transmission of a second random access preamble on any secondary cell in said primary cell group such that any second secondary cell in said primary cell group does not include usable random access resources for said wireless device; and

iii) receive on a primary cell a random access response comprising a timing advance command configured to cause substantial alignment of reception timing of uplink signals in frames and subframes of said secondary cell group at a base station.

8. The wireless device of claim 7 , wherein said primary cell group comprises said primary cell and one or more second secondary cells.

9. The wireless device of claim 7 , wherein said control command comprises:

a) a mask index; and

b) a random access preamble identifier.

10. The wireless device of claim 7 , wherein said first random access preamble is transmitted on uplink random access resources identified by:

a) a plurality of random access resource parameters of said secondary cell; and

b) said control command.

11. The wireless device of claim 7 , wherein said at least one 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.

12. The wireless device of claim 7 , wherein said instructions further cause said wireless device to transmit, said first random access preamble on random access resources of said secondary cell, transmission timing of said random access preamble determined, at least in part, employing a synchronization signal received on an activated cell in said secondary cell group.

13. 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 to a wireless device at least one message to cause:

1) assignment of each of a plurality of secondary cells in a plurality of cells to one of a plurality of cell groups comprising:

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

(b) a secondary cell group comprising a second subset of said plurality of secondary cells; and

2) configuration of random access resources for at least one secondary cell in said plurality of secondary cells; and

ii) transmit to said wireless device a control command being:

1) configurable to cause transmission of a first random access preamble on a secondary cell in said secondary cell group; and

2) unconfigurable to cause transmission of a second random access preamble on any secondary cell in said primary cell group such that any secondary cell in said primary cell group does not include usable random access resources for said wireless device; and

iii) transmit on a primary cell a random access response comprising a timing advance command configured to cause substantial alignment of reception timing of uplink signals in frames and subframes of said secondary cell group at said base station.

14. The base station of claim 13 , wherein said primary cell group comprises said primary cell and one or more second secondary cells.

15. The base station of claim 13 , wherein said control command comprises:

a) a mask index; and

b) a random access preamble identifier.

16. The base station of claim 13 , wherein said first random access preamble is received on uplink random access resources identified by:

a) a plurality of random access resource parameters of said secondary cell; and

b) said control command.

17. The base station of claim 13 , wherein said at least one 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 from said base station a timing advance command to adjust uplink transmission timing of a commanded cell group in said plurality of cell groups.

18. The base station of claim 13 , wherein said instructions further cause said base station to receive said first random access preamble on random access resources of said secondary cell, transmission timing of said random access preamble determined, at least in part, employing a synchronization signal of an activated cell in said secondary cell group.

19. A method comprising:

a) transmitting by a base station at least one message causing in a wireless device:

i) assignment of each of a plurality of secondary cells in a plurality of cells to one of a plurality of cell groups comprising:

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

2) a secondary cell group comprising a second subset of said plurality of secondary cells; and

ii) configuration of random access resources for at least one secondary cell in said plurality of secondary cells; and

b) transmitting to said wireless device a control command being:

i) configurable to cause transmission of a first random access preamble on a secondary cell in said secondary cell group; and

ii) unconfigurable to cause transmission of a second random access preamble on any secondary cell in said primary cell group such that any second secondary cell in said primary cell group does not include usable random access resources for said wireless device; and

c) transmitting on a primary cell a random access response comprising a timing advance command configured to cause substantial alignment of reception timing of uplink signals in frames and subframes of said secondary cell group at said base station.

20. The method of claim 19 , wherein said primary cell group comprises said primary cell and one or more second secondary cells.

21. The method of claim 19 , wherein said control command is transmitted on a cell employed for scheduling uplink resources for said secondary cell.

22. The method of claim 19 , wherein said control command comprises:

a) a mask index; and

b) a random access preamble identifier.

23. The method of claim 19 , wherein transmission power of said first random access preamble is calculated employing one or more power control parameters.

24. The method of claim 19 , wherein said first random access preamble is received on uplink random access resources identified by:

a) a plurality of random access resource parameters of said secondary cell; and

b) said control command.