A Stable LMS Adaptive Channel Estimation Algorithm for MIMO-OFDM Systems Based On STBC

Multiple input multiple output (MIMO) technology is combined with orthogonal frequency division multiplexing (OFDM) to provide robustness and high spectral efficiency. Adaptive channel estimation is the most important and difficult task in MIMO-OFDM systems where the channel is rapidly time varying. RLS and LMS are commonly used adaptive algorithm for channel estimation in wireless systems. In this paper, a stable LMS adaptive algorithm is proposed for channel estimation in MIMO-OFDM systems based on space time block coding (STBC). Recursive least square (RLS) and Least mean square (LMS) adaptive channel estimators are discussed. The stability of proposed LMS and RLS algorithms is compared in term of μ. From the simulation results, it is observed that proposed LMS is more stable than RLS for a particular range of μ with less computational complexity. Moreover, the proposed LMS provides better performance with less training sequences compare to RLS.