Beamforming signaling in a wireless network
Methods, apparatus, and systems for wireless communications are described. A first base station may be configured to transmit a measurement information message to a wireless device. The measurement information message may comprise at least one information element, wherein the at least one information element indicates one or more first resource blocks corresponding to first signals associated with the first base station and one or more second resource blocks corresponding to second signals associated with a second base station. The wireless device may compute a precoding matrix indicator (PMI) based at least in part on first signals received from the first base station and second signals received from the second base station. The wireless device may transmit channel state information comprising the computed PMI to the first base station. The first base station may transmit at least one data packet beamformed according to a precoding matrix associated with the computed PMI.
1. A method for use in a wireless device, the method comprising:
receiving, from a first base station, a measurement information message comprising at least one information element;
receiving, based on the at least one information element, first signals from the first base station and second signals from a second base station;
computing a precoding matrix indicator (PMI) based at least in part on the first signals received from the first base station and the second signals received from the second base station;
transmitting channel state information comprising the computed PMI to the first base station; and
receiving, from the first base station, at least one data packet beamformed according to a precoding matrix associated with the computed PMI.
2. The method of claim 1 , wherein the at least one information element indicates one or more resource blocks associated with the first signals.
3. The method of claim 1 , wherein the at least one information element indicates one or more resource blocks associated with the second signals.
4. The method of claim 1 , wherein the at least one information element is based, at least in part, on one or more information elements received by the first base station from the second base station.
5. The method of claim 1 , wherein computing the PMI is based at least in part on measurement of the first signals received from the first base station and on measurement of the second signals received from the second base station.
6. The method of claim 5 , wherein computing the PMI is based at least in part on reducing downlink inter-cell interference received from the second base station.
7. The method of claim 1 , wherein computing the PMI comprises selecting the PMI from a plurality of predetermined PMIs.
8. The method of claim 1 , wherein computing the PMI comprises selecting the PMI from a subset of a precoding codebook indicated by a codebook subset restriction bitmap parameter.
9. The method of claim 1 , wherein the PMI comprises a precoding matrix indicator for a sub-band of a downlink carrier.
10. The method of claim 1 , wherein the first signals are first reference signals associated with the first base station and wherein the second signals are second reference signals associated with the second base station.
11. A wireless device comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the wireless device to:
receive, from a first base station, a measurement information message comprising at least one information element;
receive, based on the at least one information element, first signals from the first base station and second signals from a second base station;
compute a precoding matrix indicator (PMI) based at least in part on the first signals received from the first base station and the second signals received from the second base station;
transmit channel state information comprising the computed PMI to the first base station; and
receive, from the first base station, at least one data packet beamformed according to a precoding matrix associated with the computed PMI.
12. The wireless device of claim 11 , wherein the at least one information element indicates one or more resource blocks associated with the first signals.
13. The wireless device of claim 11 , wherein the at least one information element indicates one or more resource blocks associated with the second signals.
14. The wireless device of claim 11 , wherein the at least one information element is based, at least in part, on one or more information elements received by the first base station from the second base station.
15. The wireless device of claim 11 , wherein the instructions, when executed by the one or more processors, cause the wireless device to compute the PMI based at least in part on measurement of the first signals received from the first base station and on measurement of the second signals received from the second base station.
16. The wireless device of claim 15 , wherein the instructions, when executed by the one or more processors, cause the wireless device to compute the PMI based at least in part on reducing downlink inter-cell interference received from the second base station.
17. The wireless device of claim 11 , wherein the instructions, when executed by the one or more processors, cause the wireless device to compute the PMI based on selecting the PMI from a plurality of predetermined PMIs.
18. The wireless device of claim 11 , wherein the instructions, when executed by the one or more processors, cause the wireless device to compute the PMI based on selecting the PMI from a subset of a precoding codebook indicated by a codebook subset restriction bitmap parameter.
19. The wireless device of claim 11 , wherein the PMI comprises a precoding matrix indicator for a sub-band of a downlink carrier.
20. The wireless device of claim 11 , wherein the first signals are first reference signals associated with the first base station and wherein the second signals are second reference signals associated with the second base station.
21. A first base station comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the first base station to:
transmit, to a wireless device, a measurement information message comprising at least one information element, wherein the at least one information element indicates one or more first resource blocks corresponding to first signals associated with the first base station and indicates one or more second resource blocks corresponding to second signals associated with a second base station;
receive, from the wireless device, channel state information comprising a precoding matrix indicator (PMI) computed based at least in part on the first signals and the second signals; and
transmit, to the wireless device, at least one data packet employing beamforming according to a precoding matrix associated with the received PMI.
22. The first base station of claim 21 , wherein the instructions, when executed by the one or more processors, further cause the first base station to:
receive, from the second base station, first information associated with the one or more second resource blocks corresponding to the second signals; and
generate the at least one information element based, at least in part, on the first information.
23. The first base station of claim 21 , wherein the PMI is based at least in part on measurement of the first signals associated with the first base station and on measurement of the second signals associated with the second base station.
24. The first base station of claim 23 , wherein the PMI is based at least in part on reducing downlink inter-cell interference received from the second base station.
25. The first base station of claim 21 , wherein the PMI is selected from a plurality of predetermined PMIs.
26. The first base station of claim 21 , wherein the PMI comprises a precoding matrix indicator or a sub-band of a downlink carrier.
27. The first base station of claim 21 , wherein the first signals are first reference signals associated with the first base station and wherein the second signals are second reference signals associated with the second base station.
28. A method for use in a first base station, the method comprising:
transmitting, by the first base station and to a wireless device, a measurement information message comprising at least one information element, wherein the at least one information element indicates one or more first resource blocks corresponding to first signals associated with the first base station and indicates one or more second resource blocks corresponding to second signals associated with a second base station;
receiving, by the first base station and from the wireless device, channel state information comprising a precoding matrix indicator (PMI) computed based at least in part on the first signals and the second signals; and
transmitting, by the first base station, at least one data packet employing beamforming according to a precoding matrix associated with the received PMI.
29. The method of claim 28 , further comprising:
receiving, from the second base station, first information associated with the one or more second resource blocks corresponding to the second signals; and
generating the at least one information element based, at least in part, on the first information.
30. The method of claim 28 , wherein the PMI is based at least in part on measurement of the first signals associated with the first base station and on measurement of the second signals associated with the second base station.
31. The method of claim 30 , wherein the PMI is based at least in part on reducing downlink inter-cell interference received from the second base station.
32. The method of claim 28 , wherein the PMI is selected from a plurality of predetermined PMIs.
33. The method of claim 28 , wherein the PMI comprises a precoding matrix indicator or a sub-band of a downlink carrier.
34. The method of claim 28 , wherein the first signals are first reference signals associated with the first base station and wherein the second signals are second reference signals associated with the second base station.
35. A system comprising:
a wireless device, wherein the wireless device is configured to:
receive, based on at least one information element received from a first base station, first signals from the first base station and second signals from a second base station;
compute a precoding matrix indicator (PMI) based at least in part on the first signals received from the first base station and the second signals received from the second base station;
transmit channel state information comprising the computed PMI to the first base station; and
receive, from the first base station, at least one data packet beamformed according to a precoding matrix associated with the computed PMI; and
the first base station, wherein the first base station is configured to:
transmit, to the wireless device, a measurement information message comprising the at least one information element, wherein the at least one information element indicates one or more first resource blocks corresponding to the first signals and one or more second resource blocks corresponding to the second signals;
receive, from the wireless device, the channel state information comprising the PMI computed based at least in part on the first signals and the second signals; and
transmit, to the wireless device, the at least one data packet employing beamforming according to the precoding matrix associated with the received PMI.
36. The system of claim 35 , wherein the first base station is further configured to:
receive, from the second base station, first information associated with the one or more second resource blocks corresponding to the second signals; and
generate the at least one information element based, at least in part, on the first information.
37. The system of claim 35 , wherein the wireless device is configured to compute the PMI based at least in part on measurement of the first signals received from the first base station and on measurement of the second signals received from the second base station.
38. The system of claim 37 , wherein the wireless device is configured to compute the PMI based at least in part on reducing downlink inter-cell interference received from the second base station.
39. The system of claim 35 , wherein the wireless device is configured to compute the PMI based on selecting the PMI from a plurality of predetermined PMIs.
40. The system of claim 35 , wherein the first signals are first reference signals associated with the first base station and wherein the second signals are second reference signals associated with the second base station.