Performance Evaluation of MIMO-OFDM with Twin Turbo Decoder

Yasuyuki HATAKAWA  Noriaki MIYAZAKI  Toshinori SUZUKI  

IEICE TRANSACTIONS on Communications   Vol.E92-B   No.1   pp.228-236
Publication Date: 2009/01/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E92.B.228
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
iterative decoder,  multiple-input multiple-output,  FEC (Forward Error Correction),  correlated channel,  turbo coding,  computational complexity,  

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This paper proposes Twin Turbo (T2) MIMO-OFDM (Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing). The advanced iterative decoder, called the T2 decoder, decreases the transmission error rate compared to conventional turbo decoders because it uses the correlation information among the bits mapped on an identical symbol of multi-level modulation and updates the channel reliability. When T2 is applied to a MIMO-OFDM, the required symbol energy to noise power density ratio (Es/N0) can be reduced more effectively than when T2 is applied to SISO (Single Input Single Output). This is because T2 can use the correlation among the bits not only mapped on an identical symbol but also transmitted from different antennas. Moreover, T2 achieves good performance in a correlated MIMO channel because the average minimum squared Euclidean distances between symbol replica candidates consisting of signals transmitted from multiple transmitter antennas are reduced. Computer simulations verify that the required Es/N0 of T2 MIMO-OFDM using 16QAM is 1.9 dB lower than that of a conventional turbo decoder when the correlation coefficients of transmitter and receiver antennas are 0.8. A computational complexity analysis clarifies the relation between the increase in computational complexity and the reduction in the required Es/N0.