Low complexity estimation of fast fading radio channels for higher order modulation

This paper proposes a technique for near optimal estimation of doubly selective fast-fading radio channels with low computational cost. The channel is characterized by an autoregressive (AR) model. A Kalman filter combined with a zero phase filter smoother is used to estimate the channel gains using the detected symbols in a turbo equalization and decoding scheme. It is demonstrated that, compared to other methods, this technique provides a superior bit error rate performance with a low computational cost for fast fading channels. The proposed technique is applied to higher order modulation schemes and the error-rate performance is evaluated. In contrast to other techniques for fast fading channels, the error floor for this technique is at a much higher SNR level.