Random Access Process in a Wireless Device

1 . A method comprising:

a) receiving, by a wireless device to communicate employing a plurality of cells, at least one control message from a base station, said at least one control message causing in said wireless device:

i) configuration of a primary cell and at least one secondary cell in said plurality of cells; and

ii) assignment of each of 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 transmitted on said primary cell as a primary timing reference; and

(2) at least one secondary cell group, a secondary cell group in said at least one 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 on an activated secondary cell of said secondary cell group as a secondary timing reference;

b) initiating, by said wireless device, a first random access process on a first uplink carrier of a first cell in said plurality of cells in response to receiving a first control command;

c) receiving, by said wireless device, a second control command for transmission of a second random access preamble on a second uplink carrier of a second cell in said plurality of cells while said first random access process is on-going, said second cell being different from said first cell; and

d) determining, by said wireless device, employing a pre-defined rule:

i) to continue with said first random access process and ignore said second control command; or

ii) to abort said first random access process and to transmit said second random access preamble.

2 . The method of claim 1 , wherein said pre-defined rule determines to continue with said first random access process if:

a) said first cell is said primary cell; and

b) said second cell is a secondary cell in said secondary cell group.

3 . The method of claim 1 , wherein said pre-defined rule determines to continue with said first random access process if:

a) said first cell is a secondary cell in said secondary cell group; and

b) said second cell is said primary cell.

4 . The method of claim 1 , wherein said pre-defined rule determines to continue with said first random access process and ignore said second control command.

5 . The method of claim 1 , 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.

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

a) a mask index; and

b) a preamble identifier of a random access preamble.

7 . The method of claim 1 , wherein said first control command further comprises an index identifying said first cell only if said control command is not transmitted on said first cell.

8 . The method of claim 1 , wherein said first control command further comprises an index identifying said first cell only if said control command is not transmitted on said first cell.

9 . The method of claim 1 , wherein said at least one control message further causes in said wireless device configuration of random access resources for said first cell and said second cell.

10 . The method of claim 1 , wherein said at least one control message comprises a plurality of common parameters for said first cell and said second cell, said plurality of common parameters comprising:

a) a first plurality of random access resource parameters identifying first random access resources for said first cell; and

b) a second plurality of random access resource parameters identifying second random access resources for said second cell.

11 . A method comprising:

a) receiving, by a wireless device to communicate employing a plurality of cells, at least one control message from a base station, said at least one control message causing in said wireless device:

i) configuration of a primary cell and at least one secondary cell in said plurality of cells; and

ii) assignment of each of 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) at least one secondary cell group, a secondary cell group in said at least one secondary cell group comprising a second subset of said at least one secondary cell;

b) initiating, by said wireless device, a first random access process on a first uplink carrier of a first cell in said plurality of cells in response to receiving a first control command;

c) receiving, by said wireless device, a second control command for transmission of a second random access preamble on a second uplink carrier of a second cell in said plurality of cells while said first random access process is on-going; and

d) determining, by said wireless device, employing a pre-defined rule:

iii) to continue with said first random access process and ignore said second control command; or

iv) to abort said first random access process and to transmit said second random access preamble.

12 . The method of claim 11 , wherein said pre-defined rule determines to abort said first random access process if:

a) said first cell is said primary cell; and

b) said second cell is a secondary cell in said secondary cell group.

13 . The method of claim 11 , wherein said pre-defined rule determines to abort said first random access process and to transmit said second random access preamble.

14 . The method of claim 11 , wherein said first control command comprises:

a) a mask index; and

b) a preamble identifier of a random access preamble.

15 . 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 causing in said wireless device:

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

(2) assignment of each of 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; and

(b) at least one secondary cell group, a secondary cell group in said at least one secondary cell group comprising a second subset of said at least one secondary cell;

ii) initiate a first random access process on a first uplink carrier of a first cell in said plurality of cells in response to receiving a first control command;

iii) receive a second control command for transmission of a second random access preamble on a second uplink carrier of a second cell in said plurality of cells while said first random access process is on-going; and

iv) determine employing a pre-defined rule:

(1) to continue with said first random access process and ignore said second control command; or

(2) to abort said first random access process and to transmit said second random access preamble.

16 . The wireless device of claim 15 , wherein said pre-defined rule determines:

a) to continue with said first random access process if said first random access preamble is transmitted before reception of said second control command; and

b) to abort said first random access process if said second control command is received before transmission of said first random access preamble.

17 . The wireless device of claim 15 , wherein said pre-defined rule determines to abort said first random access process if:

a) said first cell is a secondary cell in said secondary cell group; and

b) said second cell is said primary cell.

18 . The wireless device of claim 15 , wherein said first control command comprises:

a) a mask index; and

b) a preamble identifier of a random access preamble.

19 . The wireless device of claim 15 , wherein said at least one control message comprises a plurality of common parameters for said first cell and said second cell, said plurality of common parameters comprising:

a) a first plurality of random access resource parameters identifying first random access resources for said first cell; and

b) a second plurality of random access resource parameters identifying second random access resources for said second cell.

20 . The wireless device of claim 15 , wherein said at least one control message further causes in said wireless device configuration of random access resources for said first cell and said second cell.