A new adaptive equalizer with a channel estimator for mobile radio communications

For unknown mobile radio channels with severe intersymbol interference (ISI), a maximum likelihood sequence estimator needs to handle both postcursors and precursors, like a decision feedback equalizer (DFE) having both linear and feedback filters. Consequently, such an equalizer is too complex to be practical. The paper presents the performance of a new reduced-state soft decision feedback Viterbi equalizer (RSSDFVE) and a modified reduced state sequence estimator(RSSE) with a channel estimator and predictor. Two profile Rayleigh fading channel models with a Doppler frequency shift are used in the simulation. In order to update the RSSDFVE and RSSE to track the changes of fading channels, different channel estimation techniques are discussed in this paper. The simulation results are compared with a recursive least square (RLS) decision feedback equalizer (DFE) and a maximum likelihood sequence estimator (MLSE).

[1]  Norman Morrison,et al.  Introduction to Sequential Smoothing and Prediction , 1969 .

[2]  T. Le-Ngoc,et al.  Adaptive decision feedback equalization with MLSE based on predicted signals , 1993, Proceedings of ICC '93 - IEEE International Conference on Communications.

[3]  D. D. Falconer,et al.  Adaptive channel memory truncation for maximum likelihood sequence estimation , 1973 .

[4]  K. Fukawa,et al.  Adaptive equalization with RLS-MLSE for frequency-selective fast fading mobile radio channels , 1991, IEEE Global Telecommunications Conference GLOBECOM '91: Countdown to the New Millennium. Conference Record.

[5]  Tor Aulin,et al.  Simultaneous data detection and channel estimation with the Viterbi algorithm , 1994, Proceedings of IEEE Vehicular Technology Conference (VTC).

[6]  T. Le-Ngoc,et al.  An adaptive combined DFE/RSSE structure for unknown channel with severe ISI , 1993, Proceedings of GLOBECOM '93. IEEE Global Telecommunications Conference.

[7]  Won Lee,et al.  A Maximum-Likelihood Sequence Estimator with Decision-Feedback Equalization , 1977, IEEE Trans. Commun..

[8]  Abdol Hamid Aghvami,et al.  A channel model and a novel adaptive equalizer for mobile radio communications , 1993, Proceedings of GLOBECOM '93. IEEE Global Telecommunications Conference.

[9]  R. Steele,et al.  Soft decision feedback equaliser for CPM signals , 1991, ICC 91 International Conference on Communications Conference Record.

[10]  Riccardo Raheli,et al.  Applications of per-survivor processing to mobile digital communications , 1993, Proceedings of GLOBECOM '93. IEEE Global Telecommunications Conference.

[11]  Alexandra Duel-Hallen,et al.  Delayed decision-feedback sequence estimation , 1989, IEEE Trans. Commun..

[12]  G. David Forney,et al.  Maximum-likelihood sequence estimation of digital sequences in the presence of intersymbol interference , 1972, IEEE Trans. Inf. Theory.

[13]  John G. Proakis,et al.  Joint data detection and channel estimation for rapidly fading channels , 1992, [Conference Record] GLOBECOM '92 - Communications for Global Users: IEEE.

[14]  Shahid U. H. Qureshi,et al.  Reduced-state sequence estimation with set partitioning and decision feedback , 1988, IEEE Trans. Commun..

[15]  Sirikiat Lek Ariyavisitakul,et al.  A Decision Feedback Equalizer with Time-Reversal Structure , 1992, IEEE J. Sel. Areas Commun..