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A ReducedComplexity Signal Detection Scheme Employing ZF and KBest Algorithms for OFDM/SDM
Takafumi FUJITA Atsushi OHTA Takeshi ONIZAWA Takatoshi SUGIYAMA
Publication
IEICE TRANSACTIONS on Communications
Vol.E88B
No.1
pp.6675 Publication Date: 2005/01/01
Online ISSN:
DOI: 10.1093/ietcom/e88b.1.66
Print ISSN: 09168516 Type of Manuscript: Special Section PAPER (Special Section on Multicarrier Signal Processing Techniques for Next Generation Mobile CommunicationsPart 1) Category: Space Division Multiplexing Keyword: OFDM, SDM, MIMO, MLD, ZeroForcing, Kbest, Malgorithm, IEEE 802.11a,
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Summary:
This paper proposes a reducedcomplexity signal detection scheme for Orthogonal Frequency Division Multiplexing with Space Division Multiplexing (OFDM/SDM) systems that utilize ZeroForcing (ZF) and Kbest algorithms. It is known that Maximum Likelihood Detection (MLD) with exhaustive search achieves mathematically optimal performance for SDM signal detection. However, it also suffers from exponential computational complexity against the number of transmit antennas and modulation order. In order to reduce the computational complexity of MLD, we apply the Kbest algorithm for signal detection. It is known that the Kbest algorithm itself inherently reduces the computational complexity of MLD because it avoids exhaustive search. In this paper, we propose the modified Kbest algorithm, which exploits the ZF algorithm for initial symbol estimation. This initial symbol estimation improves the decoding accuracy of the original Kbest algorithm. We evaluate the performance of the proposed scheme through computer simulations. The computer simulation results show that the performance degradation from the MLD algorithm is suppressed to just 1 dB or so in terms of the required E_{b}/N_{0} for packet error rate (PER) = 10^{2}, When either 16 Quadrature Amplitude Modulation (16QAM) or 64QAM is applied with three transmit and three receive antennas. In these cases, 87% and 99% fewer metric computations are required than the MLD algorithm. It is confirmed that the proposed MLD algorithm offers a significant reduction in the computational complexity from the MLD algorithm while suppressing the performance degradation.

