Channel state information transmission

1. A method comprising:

a) receiving, by a wireless device, at least one control message from a first base station, said at least one control message causing configuration of measurement parameters of said wireless device, said configuration triggering measurements of channel state information corresponding to a subset of carriers, said at least one control message causes configuration of:

i) a channel state information transmission period;

ii) a channel state information transmission resource;

iii) a channel state information measurement resource;

iv) a physical uplink control channel format; and

v) a list of carriers for said measurement of channel state information, carriers in said list of carriers belonging to at least two base stations or belonging to at least two sectors of said first base station;

b) measuring, by said wireless device, said channel state information for each active carrier in said list of carriers on a plurality of OFDM subcarriers and a first plurality of subframes determined by a measurement resource based on said configuration;

c) multiplexing and encoding said channel state measurement information based on said physical uplink control channel format;

d) spreading by multiplying said multiplexed and encoded information by a sequence generated in said wireless device;

e) transmitting said spread information employing single-carrier OFDM transmission on said channel state information transmission resource according to said channel state information transmission period; and

f) simultaneously receiving signals from a subset of active carriers in said list of carriers, said signals carrying a plurality of data packets for said wireless device, carriers in said subset of carriers belonging to said at least two base stations or belonging to at least two sectors of said first base station.

2. The method of claim 1 , wherein said measurement resource determines a plurality of subframes that are object of said channel state information measurement.

3. The method of claim 1 , wherein said channel state information is quantized separately, by said wireless device, for different active carriers in said list of carriers.

4. The method of claim 1 , wherein said channel state information is quantized jointly, by said wireless device, across active carriers in said list of carriers.

5. The method of claim 1 , wherein said channel state information is represented, by said wireless device, by a product of a first channel state information matrix and a second channel state information matrix.

6. The method of claim 5 , wherein said first channel state information matrix is global channel state information and comprises joint information about all active carriers in said list of carriers.

7. The method of claim 5 , wherein said second channel state information matrix is local channel state information and comprises separate information about different active carriers in said list of carriers.

8. The method of claim 5 , wherein said first channel state information matrix comprises information about channel eigen values.

9. The method of claim 5 , wherein said second channel state information matrix comprises information about channel eigen vectors.

10. The method of claim 5 , wherein said first channel state information matrix is left multiplied by said second channel state information matrix.

11. The method of claim 5 , wherein said first channel state information matrix is right multiplied by said second channel state information matrix.

12. The method of claim 1 , wherein said channel state information is quantized using a multiple description code.

13. The method of claim 12 , wherein said channel state information is transmitted over a plurality of separate instances of said physical uplink control channel.

14. The method of claim 13 , wherein each instance in said plurality of separate instances of said physical uplink control channel carries coarse channel state information.

15. The method of claim 1 , wherein said channel state information is encoded jointly across active carriers in said subset of carriers.

16. The method of claim 1 , wherein said channel state information for active carriers other than a primary carrier of said wireless device is encoded differentially with respect to said channel state information for said primary carrier of said wireless device.

17. The method of claim 1 , wherein said sequence is determined based on a temporary identifier assigned to said wireless device by a base station.

18. A wireless device comprising:

a) one or more communication interfaces to communicate with a first base station;

b) one or more processors; and

c) memory storing instructions that, when executed by said one or more processors, perform the following:

i) receive at least one control message from said first base station via said one or more communication interfaces, said at least one control message causing configuration of measurement parameters of said wireless device, said configuration triggering measurements of channel state information corresponding to a subset of carriers, said at least one control message causes configuration of:

(1) an uplink transmission resource;

(2) physical uplink channel format; and

(3) a list of carriers for said measurement of channel state information, carriers in said list of carriers belonging to at least two base stations or belonging to at least two sectors of said first base station;

ii) measure said channel state information for each active carrier in said list of carriers based on said configuration;

iii) multiplex and encode said channel state measurement information based on said physical uplink channel format;

iv) transmit said information employing single-carrier OFDM transmission on said uplink transmission resource; and

v) simultaneously receive signals from a subset of carriers in said list of carriers, said signals carrying a plurality of data packets for said wireless device, carriers in said subset of carriers belonging to said at least two base stations or belonging to at least two sectors of said first base station.

19. The wireless device of claim 18 , wherein said instructions, when executed by said one or more processors, encode said channel state information jointly across said subset of carriers.

20. The wireless device of claim 18 , wherein said instructions, when executed by said one or more processors, quantize said channel state information jointly across said list of carriers.