A reduced complexity channel estimator for linear modulations operating in fading dispersive channels

A reduced complexity, pilot symbol assisted channel estimator is presented in the paper for linear modulations operating in frequency selective Rayleigh fading channel. Instead of estimating the entire channel impulse response, our estimator only estimates a few derivative fading processes and uses them to construct the channel impulse response estimate. The technique is computationally efficient, especially for applications where the channel delay spread is small. The performance of our estimator, measured indirectly by the bit error of the companion Viterbi receiver, was evaluated for BPSK, with the number of state of the receiver as a parameter. It was found that a 16 state Viterbi receiver provides close to ideal performance. There is no irreducible error floor. To the contrary, a third order diversity effect is observed in a channel with a uniform delay-power profile. When the number of states in the receiver is reduced to 4, only a second order diversity effect is observed. Finally, we note that our receiver is quite robust against fast fading.