Turbo equalization using frequency-domain shortening filter for broadband single-carrier transmission over frequency-selective fading channels

The paper presents a combined scheme using a frequency-domain shortening filter and turbo equalization for broadband single-carrier QAM transmission over frequency-selective fading channels. The frequency-selective fading channel response is first converted to a shortened desired channel impulse response by a frequency-domain pre-filter (FDPE). The shortened desired channel impulse response (SCIR) and convolutional code are used in concatenation for iterative equalization/decoding. The pre-selected small number of taps of the shortened desired channel impulse response helps to reduce the complexity of the iterative equalization/decoding. The optimum selection of coefficients/taps of the frequency-domain pre-filter and desired channel impulse response to achieve the minimum mean-square error (MMSE) is discussed. Simulation results on the performance of the proposed scheme in various frequency-selective fading channels indicate a substantial performance gain as compared to other high-performance equalization/detection schemes.