Joint Optimization of Power Allocation and Detection Ordering for Closed-Loop OSIC System

Deok-Kyu HWANG  Seung-Hoon HWANG  Keum-Chan WHANG  

IEICE TRANSACTIONS on Communications   Vol.E90-B   No.12   pp.3606-3611
Publication Date: 2007/12/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.12.3606
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
MIMO,  V-BLAST,  power allocation,  ordering,  QR decomposition,  

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In this paper, we investigate a detection ordering scheme of OSIC (Ordered Successive Interference Cancellation) systems suitable for power controlled MIMO transmission. Most studies about power controlled systems have mainly focused on strategies for transmitter, while the ordering scheme optimized at open-loop system has not been modified. In a conventional ordering scheme, the ordering process is done according to the largeness and smallness relation of each sub-stream's SNR. Unlike the conventional scheme, we derive an optimized detection ordering scheme that uses proximity to the optimal SNR. Because of error propagation, our proximity based algorithm is not valid for open-loop MIMO system in many cases. An optimization problem analysis and simulation results show that the system using the proposed ordering scheme outperforms the system using the conventional ordering scheme. Furthermore, due to the nature of QR decomposition, the proposed scheme shows not only lower implementation complexity but also better BER performance compared with the conventional scheme based on pseudo-inverse.