Configuring base station and wireless device carrier groups

1. A method comprising:

a) transmitting, by a base station, at least one Radio Resource Control (RRC) message comprising:

i) a cell group index of a secondary cell in at least one secondary cell, said cell group index identifying a secondary cell group in a plurality of cell groups, said plurality of cell groups comprising:

(1) a primary cell group comprising a primary cell, uplink transmissions by a wireless device in said primary cell group employing a first synchronization signal on said primary cell as a primary timing reference; and

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

ii) MAC dedicated parameters comprising a sequence of at least one information element, an information element comprising: a first cell group index of a first secondary cell group and a timer value for a corresponding time alignment timer, said corresponding time alignment timer indicating how long said first secondary cell group is considered to be uplink time aligned; and

b) transmitting a MAC timing advance command comprising said first cell group index causing restart of said corresponding time alignment timer.

2. The method of claim 1 , wherein said primary cell group is identified by an index equal to zero.

3. The method of claim 1 , wherein said MAC timing advance command is configured to cause substantial alignment of reception timing of uplink signals in subframes of said first secondary cell group at said base station.

4. The method of claim 1 , wherein said at least one RRC message further comprises an activation timer for said at least one secondary cell.

5. The method of claim 1 , wherein said MAC timing advance command comprises:

a) a time adjustment value; and

b) said first cell group index; and

wherein said timing advance command is configured to cause substantial alignment of reception timing of uplink signals in subframes of said first secondary cell group at said base station.

6. The method of claim 1 , wherein said at least one RRC message comprises a cell-add-modify information element for said secondary cell, said cell-add-modify information element comprising a plurality of dedicated parameters for said secondary cell, said plurality of dedicated parameters comprising said cell group index.

7. 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 Radio Resource Control (RRC) message comprising:

(1) a cell group index of a secondary cell in at least one secondary cell, said cell group index identifying a secondary cell group in a plurality of cell groups, said plurality of cell groups comprising:

(a) a primary cell group comprising a primary cell, uplink transmissions by a wireless device in said primary cell group employing a first synchronization signal on said primary cell as a primary timing reference; and

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

(2) MAC dedicated parameters comprising a sequence of at least one information element, an information element comprising: a first cell group index of a first secondary cell group and a timer value for a corresponding time alignment timer, said corresponding time alignment timer indicating how long said first secondary cell group is considered to be uplink time aligned; and

ii) transmit a MAC timing advance command comprising said first cell group index causing restart of said corresponding time alignment timer.

8. The base station of claim 7 , wherein said primary cell group is identified by an index equal to zero.

9. The base station of claim 7 , wherein said MAC timing advance command is configured to cause substantial alignment of reception timing of uplink signals in subframes of said first secondary cell group at said base station.

10. The base station of claim 7 , wherein said at least one RRC message further comprises an activation timer for said at least one secondary cell.

11. The base station of claim 7 , wherein said MAC timing advance command comprises:

a) a time adjustment value; and

b) said first cell group index; and

wherein said timing advance command is configured to cause substantial alignment of reception timing of uplink signals in subframes of said first secondary cell group at said base station.

12. The base station of claim 7 , wherein said at least one RRC message comprises a cell-add-modify information element for said secondary cell, said cell-add-modify information element comprising a plurality of dedicated parameters for said secondary cell, said plurality of dedicated parameters comprising said cell group index.

13. 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 Radio Resource Control (RRC) message comprising:

(1) a cell group index of a secondary cell in at least one secondary cell, said cell group index identifying a secondary cell group in a plurality of cell groups, said plurality of cell groups comprising:

(a) a primary cell group comprising a primary cell, uplink transmissions by a wireless device in said primary cell group employing a first synchronization signal on said primary cell as a primary timing reference; and

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

(2) MAC dedicated parameters comprising a sequence of at least one information element, an information element comprising: a first cell group index of a first secondary cell group and a timer value for a corresponding time alignment timer, said corresponding time alignment timer indicating how long said first secondary cell group is considered to be uplink time aligned; and

ii) receive a MAC timing advance command comprising said first cell group index causing restart of said corresponding time alignment timer.

14. The wireless device of claim 13 , wherein said primary cell group is identified by an index equal to zero.

15. The wireless device of claim 13 , wherein said MAC timing advance command is configured to cause substantial alignment of reception timing of uplink signals in subframes of said first secondary cell group at said base station.

16. The wireless device of claim 13 , wherein said at least one RRC message further comprises an activation timer for said at least one secondary cell.

17. The wireless device of claim 13 , wherein said MAC timing advance command comprises:

a) a time adjustment value; and

b) said first cell group index; and

wherein said timing advance command is configured to cause substantial alignment of reception timing of uplink signals in subframes of said first secondary cell group at said base station.

18. The wireless device of claim 13 , wherein said at least one RRC message comprises a cell-add-modify information element for said secondary cell, said cell-add-modify information element comprising a plurality of dedicated parameters for said secondary cell.