Premium
Interwoven random unitary beamforming for MIMO broadcast channels
Author(s) -
Sattarzadeh Sayed Ata,
Olfat Ali
Publication year - 2016
Publication title -
transactions on emerging telecommunications technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.366
H-Index - 47
ISSN - 2161-3915
DOI - 10.1002/ett.3027
Subject(s) - beamforming , computer science , transmitter , scheduling (production processes) , channel state information , mimo , unitary state , channel (broadcasting) , precoding , control theory (sociology) , telecommunications , mathematics , wireless , mathematical optimization , control (management) , artificial intelligence , political science , law
We consider a multiple‐input multiple‐output broadcast channel where the transmitter performs unitary beamforming using the channel state information obtained through limited feedback from the receivers. A new feedback structure is proposed which considerably boosts the performance of the system compared with the conventional beamforming techniques like zero forcing beamforming or per user unitary and rate control. Because of the structure of the proposed feedback design, the new scheme is named interwoven random unitary beamforming or IRUB. In IRUB, the multiple‐input multiple‐output channel is in fact continuously decomposed into M orthogonal channels where the signal transmissions over them have timing offsets. User scheduling and beamforming in IRUB is very simple. User selection in IRUB is accomplished only based on the SINR feedbacks, and in each scheduling phase, only the scheduled users are inquired to send their channel direction information to the transmitter. Thereby, the feedback load of the system is considerably reduced. We provide an analysis for the achievable rate and its scaling law for the proposed scheme. Also, a 1‐bit feedback strategy is applied over IRUB to further reduce the total feedback load of the system. We further generalize IRUB for multi antenna receivers. The effectiveness of the IRUB method is validated through simulations. Copyright © 2016 John Wiley & Sons, Ltd.