Sounding reference signal

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

a) receiving at least one radio resource control (RRC) message from a base station, said at least one RRC message causing in said wireless device:

i) assignment of a carrier to a second carrier group in a plurality of carrier groups comprising a first carrier group and said second carrier group;

ii) configuration of transmissions of sounding reference signals on said carrier;

b) receiving a control command configured to cause transmission of a random access preamble on random access resources in said second carrier group;

c) receiving a random access response comprising a long time alignment value for said second carrier group and a preamble identifier; and

d) transmitting one or more of said sounding reference signals on said carrier after adjusting uplink transmission timing of said second carrier group based on said long time alignment value, said wireless device configured to not transmit any of said sounding reference signals on said carrier until said wireless device receives said random access response comprising said long time alignment value and an uplink grant.

2. The method of claim 1 , wherein said uplink grant comprises power control information.

3. The method of claim 2 , further comprising applying said power control information to uplink signals before transmitting said one or more of said sounding reference signals.

4. The method of claim 1 , wherein said adjusting uplink transmission timing causes substantial alignment of reception timing of uplink signals in frames and subframes of said second carrier group at said base station.

5. The method of claim 1 , wherein said at least one RRC message causes configuration of said random access resources.

6. A base station comprising:

a) one or more communication interfaces configured to communicate with a wireless device via at least one wireless link;

b) one or more processors; and

c) memory storing instructions that, when executed by said one or more processors, cause said base station to:

i) transmit at least one radio resource control (RRC) message causing in said wireless device:

(1) assignment of a carrier to a second carrier group in a plurality of carrier groups comprising a first carrier group and said second carrier group;

(2) configuration of transmissions of sounding reference signals on said carrier;

ii) transmit a control command configured to cause transmission of a random access preamble on random access resources in said second carrier group;

iii) transmit a random access response comprising a long time alignment value for said second carrier group and a preamble identifier; and

iv) receive one or more of said sounding reference signals on said carrier after uplink transmission timing of said second carrier group is adjusted based on said long time alignment value, wherein said base station does not receive any of said sounding reference signals on said carrier until said random access response comprising said long time alignment value and an uplink grant is transmitted by said base station.

7. The base station of claim 6 , wherein said at least one RRC message is configured to further cause in said wireless device configuration of a time alignment timer for each of said plurality of carrier groups, said time alignment timer starting or restarting in response to said wireless device receiving a timing alignment command to adjust uplink transmission timing of a commanded carrier group in said plurality of carrier groups.

8. The base station of claim 6 , wherein said at least one RRC message comprises a plurality of parameters comprising a time alignment timer parameter for each carrier group in said plurality of carrier groups.

9. The base station of claim 6 , wherein adjusting uplink transmission timing causes substantial alignment of reception timing of uplink signals in frames and subframes of said second carrier group at said base station.

10. The base station of claim 6 , wherein uplink transmissions by said wireless device in said first carrier group employ a first synchronization signal transmitted on said first carrier.

11. A wireless device comprising:

a) one or more communication interfaces configured to communicate with a base station via at least one wireless link;

b) one or more processors; and

c) memory storing instructions that, when executed by said one or more processors, cause said wireless device to:

i) receive at least one radio resource control (RRC) message from said base station, said at least one RRC message causing in said wireless device:

(1) assignment of a carrier to a second carrier group in a plurality of carrier groups comprising a first carrier group and said second carrier group;

(2) configuration of transmissions of sounding reference signals on said carrier;

ii) receive a control command configured to cause transmission of a random access preamble on random access resources in said second carrier group;

iii) receive a random access response comprising a long time alignment value for said second carrier group and a preamble identifier; and

iv) transmit one or more of said sounding reference signals on said carrier after adjusting uplink transmission timing of said second carrier group based on said long time alignment value, said wireless device configured to not transmit any of said sounding reference signals on said carrier until said wireless device receives said random access response comprising said long time alignment value and an uplink grant.

12. The wireless device of claim 11 , wherein said uplink grant comprises power control information.

13. The wireless device of claim 12 , wherein said instructions, when executed, further cause said wireless device to apply said power control information to uplink signals before transmitting said one or more of said sounding reference signals.

14. The wireless device of claim 11 , wherein said adjusting uplink transmission timing causes substantial alignment of reception timing of uplink signals in frames and subframes of said second carrier group at said base station.