Joint transmissions to a station
This disclosure provides systems, methods and apparatuses for concurrently transmitting beamformed data from each of a plurality of access points (APs) to a wireless station (STA). In some implementations, the plurality of APs may operate as a distributed antenna array, and carrier signals of the plurality of APs may be synchronized with each other. A beamforming steering matrix may be determined for each of the plurality of APs, and beamformed data may be concurrently transmitted from each of the plurality of APs to the STA based on corresponding ones of the plurality of beamforming steering matrices.
1. A method for wireless communication, performed by a wireless station (STA), comprising:
receiving one or more sounding sequences from each of a plurality of access points (APs);
estimating, for each of the plurality of APs, a carrier frequency of the respective AP based at least in part on the one or more corresponding sounding sequences;
transmitting, to each of the plurality of APs, correction information indicating a frequency offset between the carrier frequency of the respective AP and a target carrier frequency based at least in part on a corresponding one of the estimated carrier frequencies;
receiving a beamformed test frame transmitted from two or more of the plurality of APs;
estimating phase differences between the two or more APs based on the beamformed test frame; and
transmitting, to each of the two or more APs, a feedback frame including one or more correction factors based on the estimated phase differences between the two or more APs.
2. The method of claim 1 , wherein the one or more sounding sequences are contained in one or more of a null data packet announcement (NDPA) or a null data packet (NDP).
3. The method of claim 1 , further comprising:
receiving a null data packet (NDP) from each of the two or more APs; and
transmitting, to each of the two or more APs, a compressed beamforming report (CBR) based on a corresponding one of the received NDPs.
4. The method of claim 3 , wherein the NDPs are concurrently received from the two or more APs.
5. The method of claim 3 , wherein the CBRs are concurrently transmitted to the two or more APs.
6. A wireless station (STA) comprising:
at least one modem;
at least one processor communicatively coupled with the at least one modem; and
at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor in conjunction with the at least one modem, causes the STA to:
receive one or more sounding sequences from each of a plurality of access points (APs) configured to operate as a distributed antenna array;
estimate, for each of the plurality of APs, a carrier frequency of the respective AP based at least in part on the one or more corresponding sounding sequences;
transmit, to each of the plurality of APs, correction information indicating a frequency offset between the carrier frequency of the respective AP and a target carrier frequency based at least in part on a corresponding one of the estimated carrier frequencies;
receive a beamformed test frame transmitted from two or more of the plurality of APs;
estimate phase differences between the two or more APs based on the beamformed test frame; and
transmit, to each of the two or more APs, a feedback frame including one or more correction factors based on the estimated phase differences between the two or more APs.
7. The STA of claim 6 , wherein the one or more sounding sequences are contained in one or more of a null data packet announcement (NDPA) or a null data packet (NDP).
8. The STA of claim 6 , wherein execution of the processor-readable code further causes the STA to:
receive a null data packet (NDP) from each of the two or more APs; and
transmit, to each of the two or more APs, a compressed beamforming report (CBR) based on a corresponding one of the received NDPs.
9. The STA of claim 8 , wherein the NDPs are concurrently received from the two or more APs.
10. The STA of claim 8 , wherein the CBRs are concurrently transmitted to the two or more APs.