A reduced complexity MIMO Broadcast scheme: a way between opportunistic and dirty paper implementation"

Authors: Nizar Zorba, Ana I. Pérez-Neira, Miguel A. Lagunas

Affiliation: Universitat Politecnica Catalunya and CTTC, Barcelona

 
e-mail: nizar.zorba@cttc.es ,  anuska@gps.tsc.upc.es  , m.a.lagunas@cttc.es

Abstract:

Departing from the opportunistic schemes in Multiuser MIMO schedulers, the paper studies practical implementations of the Dirty Paper scheme. The scheduler measures the Spatial Power Density function of the arriving signal and, with a successively blocking technique, it points its beams in the direction of maximum power density. From this basic scheme, the paper develops different strategies that offer different degrees of latency and fairness and that demand different degrees of  CSIT (Channel State Information at the Transmitter) . Only the selected users are asked to provide CSI (from SNIR to full CSI) to the transmitter side. The goal is to always keep a small load on the feedback link while at the same time providing almost all of the benefits of full CSI scenarios. The proposed scheme is studied for different mobile scenarios and compared against other transmission schemes as Zero-Forcing or QR beamforming.