US 9,813,995 B2
Interference cancellation
Mohammad Khojastepour, Lawrenceville, NJ (US); Karthikeyan Sundaresan, Howell, NJ (US); Eugene Chai, Princeton, NJ (US); and Sampath Rangarajan, Bridgewater, NJ (US)
Assigned to NEC CORPORATION, Tokyo (JP)
Filed by NEC Laboratories America, Inc., Princeton, NJ (US)
Filed on Aug. 5, 2015, as Appl. No. 14/818,447.
Application 14/818,447 is a division of application No. 14/560,723, filed on Dec. 4, 2014.
Claims priority of provisional application 61/949,613, filed on Mar. 7, 2014.
Claims priority of provisional application 61/911,627, filed on Dec. 4, 2013.
Prior Publication US 2015/0381335 A1, Dec. 31, 2015
This patent is subject to a terminal disclaimer.
Int. Cl. H04W 52/14 (2009.01); H04B 7/0413 (2017.01); H04B 7/0456 (2017.01); H04B 15/00 (2006.01); H04L 5/16 (2006.01); H04W 72/04 (2009.01); H04W 72/08 (2009.01); H04B 7/04 (2017.01); H04L 5/00 (2006.01); H04W 52/24 (2009.01); H04B 17/345 (2015.01); H04B 7/022 (2017.01); H04B 7/06 (2006.01)
CPC H04W 52/14 (2013.01) [H04B 7/0413 (2013.01); H04B 7/0421 (2013.01); H04B 7/0456 (2013.01); H04B 15/00 (2013.01); H04L 5/0048 (2013.01); H04L 5/16 (2013.01); H04W 72/0406 (2013.01); H04W 72/082 (2013.01); H04B 7/022 (2013.01); H04B 7/0619 (2013.01); H04B 17/345 (2015.01); H04W 52/241 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A method implemented in an access point (AP) used in a wireless communications system including a first uplink (UL) client device, a second UL client device, a first downlink (DL) client device, and a second DL client device, the method comprising:
transmitting a first pilot signal to the first and second DL client devices;
receiving second pilot signals from the first and second UL client devices;
estimating, according to the second pilot signals, channels H01U between the AP and the first UL client device and H02U between the AP and the second UL client device;
receiving, from the first DL client device, feedback DL channel state information (CSI) H10D between the first DL client device and the AP and, from the second DL client device, feedback DL CSI H20D between the second DL client device and the AP;
receiving first UL-DL CSI from the first DL client device and second UL-DL CSI from the second DL client device; and
transmitting first precoder V1 to the first UL client device;
wherein the first and second UL client devices and the first and second DL client devices receive first precoder V1, wherein the second UL client device determines second precoder V2 for the second UL client device, and wherein the first and second DL client devices determine first receive filter U1 for the first DL client device and second receive filter U2 for the second DL client device, respectively, along with second precoder V2 by using first precoder V1;
determining precoder Vo for the AP to maximize DL stream rate of N downlink streams, wherein the DL stream rate is expressed as
RDL comprising Rate (U1H10DV1) and Rate (U2H20DV2),
where V1 and V2 are two N×N/2 precoding matrices for the first and second DL client devices and form N×N precoder V0=[V1 V2].