Adaptive Modulation with Space-Time Block Coding for MIMO-OFDM Systems

Space-time block coding (STBC) scheme has proved to be efficient in enhancing the performance of communication systems in terms of both bit-error-rate (BER) and symbol-error-rate (SER). Adaptive bit and power allocation (ABPA), on the other hand, is an adaptive modulation scheme that assigns an optimum symbol constellation and power to all subcarriers in a multi-carrier system to improve spectral and power efficiency. In this work, we combine a lookup matrix based ABPA algorithm with subchannel grouping (LM-SG-ABPA) and STBC for orthogonal frequency division multiplexing (OFDM) systems to further enhance the performance and support high data rate applications. Numerical results showed that the proposed transmission structure achieves not only a significantly higher spectral and power efficiency over systems that do not employ any ABPA schemes, but also a better error probability performance in a multiple-input multiple-output (MIMO) channel