Least-squares channel estimation assisted by self-interference cancellation for mobile PRP-OFDM applications

A least-squares (LS) channel estimation (CE) technique is investigated in this paper in order to apply pseudo-random-postfix orthogonal-frequency-division multiplexing (PRP-OFDM) communications onto mobile applications, operating on a rapidly time-varying frequency-selective fading channel. The proposed technique takes advantage of several self-interference cancellation (SIC) methods to effectively and timely reduce multipath interference (MPI), inter-symbol interference (ISI) and inter-block interference (IBI). Therefore, it can overcome frequency-selectivity caused by multipath fading and time-selectivity caused by mobility; especially, OFDM communication is often anticipated to operate in environments where both wide Doppler spread and long delay spread exist. The proposed technique can achieve lower CE errors and lower bit error probabilities than the conventional techniques exploiting a time-averaging method because the moving-averager employed in conventional PRP-OFDM CEs cannot function in a mobile environment. Meanwhile, a generic estimator is performed serially, block by block, to reduce computational complexity without assistance from a priori channel information. Extensive computer simulations verify the improvements provided by the proposed technique.