CPC H04B 7/024 (2013.01) [H04B 7/0456 (2013.01); H04B 7/0617 (2013.01); H04L 5/0048 (2013.01)] | 25 Claims |
1. A method performed by a distributed base station system of a wireless communication network, the distributed base station system comprising a base band unit (BBU) and a remote radio unit (RRU) connected to each other over a fronthaul link, the RRU being connected to N antennas, the method comprising:
receiving, by the RRU, a first reference signal from a number of User Equipment (UEs) wirelessly connected to the RRU;
sending, by the RRU, the first reference signal over the fronthaul link to the BBU;
determining, by a BBU system, information of first beamforming weights W1 based on the first reference signal;
sending, by the BBU, the information of the first beamforming weights W1 over the fronthaul link to the RRU;
obtaining, by the RRU, uplink signals y as received at the N antennas from the number of UEs, the N uplink signals y comprising K user-layer signals overlaid with interference signals and noise, the N uplink signals further comprising a second reference signal;
determining, by the RRU, intermediate signals y based on the information of the first beamforming weights W1 and on the uplink signals y comprising the second reference signal, the intermediate signals having K+L signal components, where (K+L) is smaller than N, and L is larger than or equal to zero;
sending, by the RRU, the intermediate signals y over the fronthaul link to the BBU;
determining, by the BBU system, second beamforming weights W2 based on the second reference signal received in the intermediate signal y; and
determining, by the BBU system, output signals r, which are estimations of the K user-layer signals, based on the intermediate signals y and the second beamforming weights W2.
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