Transmit power control in multicarrier communications

1. A method comprising:

a) receiving, by a wireless device, at least one radio resource control message from a base station, said at least one radio resource control message to cause in said wireless device:

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

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) a secondary cell group comprising a second subset of said at least one secondary cell; and

b) receiving, by said wireless device, a first control packet providing a first uplink grant to transmit a first uplink packet in a first subframe of a first secondary cell;

c) computing, by said wireless device, transmission power of said first uplink packet employing, at least in part, a first parameter calculated by accumulation of an initial value and at least one power control value corresponding to a sequence of subframes, said sequence of subframes starting from an initial subframe and ending with said first subframe, said initial subframe identified by the most recent subframe before said first subframe with one of the following events:

i) a predefined transmit power parameter value updated by higher layers; and

ii) a random access response received corresponding to a transmitted random access preamble on said first secondary cell; and

d) transmitting, by said wireless device, said first uplink packet in radio resources identified by said first uplink grant.

2. The method of claim 1 , wherein said first control packet comprises said first uplink grant and a first power control field, said first power control field corresponding to a first power control value.

3. The method of claim 2 , wherein said first power control field corresponds with a pre-defined said power control value.

4. The method of claim 1 , wherein each subframe in said sequence of subframes is assigned:

a) said initial value; or

b) one power control value in said at least one power control value.

5. The method of claim 1 , further comprising receiving said predefined transmit power parameter value via a radio resource control protocol message.

6. The method of claim 1 , wherein a power control value in said at least one power control value corresponding to a subframe in said sequence of subframes is zero if one of the following conditions is satisfied:

a) no power control is received for said subframe;

b) said wireless device has reached a maximum power in said subframe and said corresponding power control value is positive; and

c) said wireless device has reached a minimum power in said subframe and said corresponding power control value is negative.

7. The method of claim 1 , wherein a power control value in said at least one power control value corresponding to a subframe in said sequence of subframes is zero if one of the following conditions is satisfied:

a) said subframe is not an uplink subframe in a TDD frame structure;

b) said wireless device has reached a maximum power in said subframe and said corresponding power control value is positive; and

c) said wireless device has reached a minimum power in said subframe and said corresponding power control value is negative.

8. The method of claim 1 , wherein:

a) said initial value is zero if said predefined transmit power parameter value is updated in said initial subframe; and

b) said initial value is the sum of a power control value in said at least one power control value and an offset value if said random access response is received.

9. The method of claim 8 , wherein said offset value corresponds to a total power ramp-up from the first to the last preamble transmitted by said wireless device during a random access process corresponding to said random access response.

10. The method of claim 1 , further comprising said at least one first control message causing configuration of power control accumulations for said first secondary cell.

11. The method of claim 1 , further comprising said first control packet enabling configuration of power control accumulations for said first secondary cell.

12. A method comprising:

a) receiving, by a wireless device, at least one radio resource control message from a base station, said at least one radio resource control message to cause in said wireless device configuration of a plurality of cells comprising a primary cell and at least one secondary cell;

b) receiving, by said wireless device, a first control packet providing a first uplink grant to transmit a first uplink packet in a first subframe of a first secondary cell;

c) computing, by said wireless device, transmission power of said first uplink packet employing, at least in part, a first parameter calculated by accumulation of an initial value and at least one power control value corresponding to a sequence of subframes, said sequence of subframes starting from an initial subframe and ending with said first subframe, said initial subframe identified by the most recent subframe before said first subframe with one of the following events:

i) a predefined transmit power parameter value updated by higher layers; and

ii) a random access response received corresponding to a transmitted random access preamble on said first secondary cell; and

d) transmitting, by said wireless device, said first uplink packet in radio resources identified by said first uplink grant.

13. The method of claim 12 , wherein each subframe in said sequence of subframes is assigned:

a) said initial value; or

b) one power control value in said at least one power control value.

14. The method of claim 12 , further comprising said at least one first control message causing configuration of power control accumulations for said first secondary cell.

15. The method of claim 12 , further comprising said first control packet enabling configuration of power control accumulations for said first secondary cell.

16. The method of claim 12 , further comprising said wireless device resetting said power control accumulation associated with a first uplink carrier of said first secondary cell if one of said events occurs.

17. 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 message from a base station, said at least one radio resource control message to cause in said wireless device configuration of a plurality of cells comprising a primary cell and at least one secondary cell;

ii) receive a first control packet providing a first uplink grant to transmit a first uplink packet in a first subframe of a first secondary cell;

iii) compute transmission power of said first uplink packet employing, at least in part, a first parameter calculated by accumulation of an initial value and at least one power control value corresponding to a sequence of subframes, said sequence of subframes starting from an initial subframe and ending with said first subframe, said initial subframe identified by the most recent subframe before said first subframe with one of the following events:

(1) a predefined transmit power parameter value updated by higher layers; and

(2) a random access response received corresponding to a transmitted random access preamble on said first secondary cell; and

iv) transmit said first uplink packet in radio resources identified by said first uplink grant.

18. The wireless device of claim 17 , wherein:

a) said initial value is zero if said predefined transmit power parameter value is updated in said initial subframe; and

b) said initial value is the sum of a power control value and an offset value if said random access response is received.

19. The wireless device of claim 17 , wherein said first control packet is received in PDCCH radio resources or EPDCCH radio resources.

20. The wireless device of claim 17 , wherein a power control value corresponding to a subframe in said sequence of subframes is zero if one of the following conditions is satisfied:

a) said subframe is not an uplink subframe in a TDD frame structure;

b) said wireless device has reached a maximum power in said subframe and a corresponding power control value is positive; and

c) said wireless device has reached a minimum power in said subframe and a corresponding power control value is negative.