Tracking behavior of adaptive equalizers in filtered multitone communication systems

Although orthogonal frequency division multiplexing (OFDM) communication systems that uses inverse discrete Fourier (IDFT) for multicarrier modulation and discrete Fourier transform (DFT) for demodulation are dominantly adopted in the current broadband communication standards, there have been some reports in recent years that discuss the shortcomings of OFDM in highly mobile and/or multiple access environments. To resolve these problems, a number of authors have proposed a shift from OFDM to filterbank-based multicarrier (FBMC) techniques. In a recent work, we presented a thorough study of filtered multitone (FMT), a class of FBMC systems, in time-varying frequency selective channels. We derived close-form equations for the optimum parameters of per-tone fractionally spaced equalizers and also signal to interference plus noise ratio (SINR) and used these to evaluate FMT in typical wireless mobile environments. These results provide an upper limit to the performance of this class of FBMC systems. In this paper, we study the performance of an adaptive channel estimation algorithms that attempts to reach this upper limit. To further improve the channel estimate, the proposed method uses a minimum mean-square error (MMSE) channel estimator and considers the fact that the channel impulse response is limited in time.