Blind equalization for short burst wireless communications

In this paper, we propose a Dual Mode Blind Equalizer based on Constant Mod ulus Algorithm (CMA), The blind equalizer is devised for short burst transm ission formats used in many current wireless TDMA systems as well as future wireless packet data systems. Blind equalization is useful for such short burst formats, since the overhead associated with training can be significa nt when only a small number of bits are transmitted at a time. The proposed equalizer overcomes the common problems associated with classic blind algo rithms, i.e., slow convergence and ill-convergence, which are detrimental t o applying blind equalization to short burst formats. Thus, it can eliminat e the overhead associated with training sequences, Also, the blind equalize r is extended to a two branch diversity combining blind equalizer. A new in itialization for fractionally spaced CMA equalizers is introduced. This gre atly improves the symbol timing recovery performance of fractionally spaced CMA equalizers with or without diversity, when applied to short bursts. Th rough simulations with quasi-static or time-varying frequency selective wir eless channels, the performance of the proposed equalizer is compared to se lection diversity and conventional equalizers with training sequences. The results indicate that its performance is far superior to that of selection diversity alone and comparable to the performance of equalizers with short training sequences. Thus, training overhead can be removed with no performa nce degradation for fast time-varying channels, and with slight performance degradation for static channels.