Adaptive Precoding for Wireless MIMO Broadcast Channels with Limited Feedback

James (Sungjin) KIM  Hojin KIM  Chang Soon PARK  Kwang Bok LEE  

IEICE TRANSACTIONS on Communications   Vol.E88-B   No.11   pp.4237-4245
Publication Date: 2005/11/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.11.4237
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Software Defined Radio Technology and Its Applications)
MIMO,  broadcast channel (BC),  adaptive precoding,  SDR implementation,  

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Recently, a number of techniques have been introduced to exploit multiuser diversity of a wireless multiple-input multiple-output (MIMO) broadcast channel (BC) that consists of a base station with t transmit antennas and K users with multiple antennas. However, prior works have ignored the rate overhead associated with feedback of MIMO BC channel state information at transmitter (CSIT), which is roughly K times larger than single-user MIMO CSIT (i.e., it is O(tr) where r = rk and rk is the number of antennas at the kth user). Considering the amount of feedback signaling, quantization is a necessity for effective feedback transmission as a form of partial CSIT. In this paper, we propose the greedy multi-channel selection diversity (greedy MCSD) scheme based on block MMSE QR decomposition with dirty paper coding (block MMSE-DP), where partial CSIT is almost sufficient. The sum-rate performance of our novel scheme approaches extremely close to the sum capacity of MIMO BC as the number of users increases, whereas the feedback overhead is reduced by a factor of 2t3/L(t2-t), in which L is the number of active channel vectors. Simulation results validate the expectation from the analysis. In addition, the proposed scheme is shown to be appropriate for reconfigurable implementation.