	US 12,218,720 B2
	Multi-user pre-coding
Ulf Gustavsson, Gothenburg (SE); Alex Alvarado, Den Bosch (NL); Frans M. J. Willems, Geldrop (NL); and Amirashkan Farsaei, Eindhoven (NL)
Assigned to TELEFONAKTIEBOLAGET LM ERICSSON (PUBL), Stockholm (SE)
Appl. No. 17/914,167
Filed by Telefonaktiebolaget LM Ericsson (publ), Stockholm (SE)
PCT Filed Apr. 1, 2020, PCT No. PCT/EP2020/059238 § 371(c)(1), (2) Date Sep. 23, 2022, PCT Pub. No. WO2021/197594, PCT Pub. Date Oct. 7, 2021.
Prior Publication US 2023/0125744 A1, Apr. 27, 2023
Int. Cl. H04B 7/04 (2017.01); H04B 7/0456 (2017.01); H04W 52/24 (2009.01); H04B 7/0452 (2017.01)

CPC H04B 7/0456 (2013.01) [H04W 52/24 (2013.01); H04B 7/0452 (2013.01)]

20 Claims

1. A pre-coding method of a multi-user, multi-antenna transmitter configured for transmission of respective signals to a plurality of users, the method comprising:

determining, for each pair of users of the plurality, a spatial correlation value for the pair of users;

sorting the plurality of users into a linear pre-coding group or a non-linear pre-coding group based on the spatial correlation values;

generating the respective signals for transmission to the users of the linear pre-coding group by application of linear pre-coding; and

generating the respective signals for transmission to the users of the non-linear pre-coding group by application of non-linear pre-coding, wherein

the plurality of users comprises a first user, a second user, and a third user,

determining, for each pair of users of the plurality, a spatial correlation value for the pair of users comprises:

for a first pair of users consisting of the first user and the second user, determining a first pairwise spatial correlation coefficient using a first channel estimate for the first user and a second channel estimate for the second user;

for a second pair of users consisting of the first user and the third user, determining a second pairwise spatial correlation coefficient using the first channel estimate for the first user and a third channel estimate for the third user; and

for a third pair of users consisting of the second user and the third user, determining a third pairwise spatial correlation coefficient using the second channel estimate for the second user and the third channel estimate for the third user, and

sorting the plurality of users into a linear pre-coding group or a non-linear pre-coding group based on the spatial correlation values comprises:

for the first user, using both the first pairwise spatial correlation coefficient and the second pairwise spatial correlation coefficient to determine whether to include the first user in the linear pre-coding group or the non-linear pre-coding group;

for the second user, using both the first pairwise spatial correlation coefficient and the third pairwise spatial correlation coefficient to determine whether to include the second user in the linear pre-coding group or the non-linear pre-coding group; and

for the third user, using both the second pairwise spatial correlation coefficient and the third pairwise spatial correlation coefficient to determine whether to include the third user in the linear pre-coding group or the non-linear pre-coding group.