Channel Estimation, Equalization of OFDM Systems with Insufficient Cyclic Prefix

Inherent inter-symbol, inter-carrier interference elimination ability of orthogonal frequency division multiplexing (OFDM) system attribute to its cyclic prefix. But the case of multipath fading channels whose the channel impulse response (CIR) length exceeds the duration of cyclic prefix (CP) causes intersymbol interference (ISI), intercarrier interference (ICI), which may degrade system performance severely. Conventional channel estimation, equalization schemes, if applied to this case of insufficient CP, suffer significant performance degradation. This paper presents a channel estimation scheme that enables the estimation of a complete CIR even beyond the CP length. A Zero-forcing (ZF) based low complexity equalizer for the suppression of insufficient CP generated interference is also derived. Simulation results for the proposed schemes show the advantage of significantly lower computational complexity, compared with earlier schemes, without any loss in performance, transmission efficiency.