Greedy user selection for zero-forcing and MMSE multiuser beamforming with channel estimation errors
In a multi-user MIMO downlink where the base station has only estimates of the channels of the users, the sum-rate of multi-user beamforming saturates at high SNR. However, this is not the case for single-user beamforming. We propose a low-complexity user scheduling algorithm that selects the number of active users based on a closed-form approximation of the average sum-rate, and in particular does not add multiple users in the single-user optimality range. In order to develop this algorithm we derive the expected value of the rate of zero-forcing beamforming and MMSE beamforming with estimated channels and modify the greedy user selection accordingly. The gain of the proposed method is shown in numerical simulations.
Las Vegas, NV
MIMO communication,channel estimation,least mean squares methods,multiuser channels,MMSE multiuser beamforming,channel estimation errors,closed-form approximation,greedy user selection,low-complexity user scheduling algorithm,multiuser MIMO downlink,zero-forcing beamforming,Broadcast channel (BC),downlink scheduling,imperfect channel state information (CSI),multiple-input multiple-output (MIMO),zero-forcing beamforming (ZFBF)
WSDMA,Base station,Beamforming,Mathematical optimization,Computer science,Scheduling (computing),MIMO,Communication channel,Precoding,Telecommunications link
1520-6149 E-ISBN : 978-1-4244-1484-0