Simple turbo MIMO scheme using arithmetic extended mapping and repetition codes

A simple turbo multi-input multi-output (MIMO) scheme using arithmetic-extended mapping and repetition codes is proposed. To mitigate performance degradation of MIMO schemes caused by spatial correlation, a soft canceller followed by minimum-mean-squared-error filter (SC-MMSE) and an iterative-decoding technique based on the turbo principle are adopted. This turbo MIMO scheme is designed by using 8-amplitude-shift keying (8-ASK) arithmetic extended mapping and a 1/4-rate repetition code. The performance of the proposed turbo MIMO scheme is verified in terms of bit error rate (BER) for a spatially correlated Rayleigh channel. The scheme exhibits a “turbo cliff” at signal-to-noise ratio (SNR) of 28 dB. Compared to a conventional MIMO scheme using MMSE with 64-quadrature-amplitude-modulation (64-QAM) mapping and a 1/2-rate turbo code, the proposed scheme improves SNR by 1.8 dB at BER of 10^-4.