Random access preamble transmission

1. A method comprising:

a) receiving, by a wireless device in a plurality of wireless devices, at least one control message from a base station, said at least one control message:

i) causing in said wireless device:

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

(2) assignment of each of said plurality of secondary cells 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 employing a first synchronization signal transmitted on said primary cell; and

(b) a secondary cell group comprising a second subset of said plurality of secondary cells, said second subset comprising a reference secondary cell, uplink transmissions in said secondary cell group employing a second synchronization signal on said reference secondary cell as a secondary timing reference; and

ii) comprising a plurality of common parameters having the same value for wireless devices in said plurality of wireless devices, said plurality of common parameters comprising the following parameters for each of at least one first secondary cell in said plurality of secondary cells:

(1) a plurality of random access resource parameters; and

(2) a plurality of power control parameters for random access preamble transmission; and

b) receiving, by said wireless device, a control command to from said base station, said control command being:

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

ii) unconfigurable to cause transmission of a second random access preamble on any secondary cell in said primary cell group; and

wherein one or more second secondary cells in said primary cell group are not configured with usable random access resources for said wireless device.

2. The method of claim 1 , further comprising receiving, by said wireless device, a control command causing said wireless device to transmit a third random access preamble to acquire uplink timing for said primary cell group, said control command configurable:

a) to be transmitted on a downlink of only said primary cell; and

b) to cause transmission of said third random access preamble on an uplink of only said primary cell.

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

4. The method of claim 1 , wherein said control command is received on a cell employed for scheduling uplink resources for said one of said at least one first secondary cell that is in said second subset.

5. The method of claim 1 , wherein each of said one or more first secondary cells in said secondary cell group is configured with a random access resource.

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

a) a mask index; and

b) a random access preamble identifier.

7. The method of claim 1 , wherein transmission power of said first random access preamble calculated employing said plurality of power control parameters.

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

a) a plurality of random access resource parameters; and

b) said control command.

9. The method of claim 1 , further comprising receiving a random access response on said primary cell, said random access response comprising a timing advance command for said secondary cell group.

10. A base station, configured to communicate employing a plurality of cells, comprising:

c) one or more communication interfaces;

d) one or more processors; and

e) 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:

(1) configured to cause in said wireless device:

(a) configuration of a primary cell and a plurality of secondary cells in said plurality of cells; and

(b) assignment of each of said plurality of secondary cells to a cell group in a plurality of cell groups, said plurality of cell groups comprising:

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

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

(2) comprising a plurality of common parameters, said plurality of common parameters comprising the following parameters for each of at least one first secondary cell in said plurality of secondary cells:

(a) a plurality of random access resource parameters; and

(b) a plurality of power control parameters for random access preamble transmission; and

ii) transmit a control command to said wireless device, said 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; and

wherein one or more second secondary cells in said primary cell group are not configured with usable random access resources for said wireless device.

11. The base station of claim 10 , wherein said instructions further cause said base station to transmit a random access response on said primary cell, said random access response comprising a timing advance command for said secondary cell group.

12. The base station of claim 11 , wherein said random access response comprises a timing advance command, said timing advance command comprising a time adjustment value, wherein said timing advance command configured to cause substantial alignment of reception timing of said uplink signals in frames and subframes of said secondary cell group at said base station.

13. The base station of claim 11 , wherein said random access preamble is received on uplink random access resources identified by:

a) a plurality of random access resource parameters; and

b) said control command.

14. 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 base station configured to communicate employing a plurality of cells with said wireless device, said at least one control message:

(1) causing in said wireless device:

(a) configuration of a primary cell and a plurality of secondary cells in said plurality of cells; and

(b) assignment of each of said plurality of secondary cells to a cell group in a plurality of cell groups, said plurality of cell groups comprising:

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

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

(2) comprising a plurality of common parameters, said plurality of common parameters comprising the following parameters for each of at least one first secondary cell in said plurality of secondary cells:

(a) a plurality of random access resource parameters; and

(b) a plurality of power control parameters for random access preamble transmission; and

iii) receive a control command from said base station, said control command:

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

(2) unconfigurable to cause transmission of a second random access preamble on any secondary cell in said primary cell group; and

wherein one or more second secondary cells in said primary cell group are not configured with usable random access resources for said wireless device.

15. The wireless device of claim 14 , 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.

16. The wireless device of claim 14 , wherein said instructions further cause said wireless device to transmit, to said base station, said first random access preamble on random access resources identified by said plurality of random access resource parameters, transmission timing of said random access preamble determined, at least in part, employing a second synchronization signal on an activated cell in said secondary cell group.

17. The wireless device of claim 14 , wherein transmission power of said first random access preamble calculated employing said plurality of power control parameters.