On the feasibility of blind equalization for EDGE systems

The main goal of this paper is to find whether or not blind equalization can be used in EDGE (enhanced data rate for GSM evolution) systems in the perspective of increasing the data rate. An EDGE system uses 8-PSK modulation as well as the binary GMSK modulation defined for GSM. The main problem is that GMSK modulation is nonlinear, but most blind equalization techniques are derived for linear modulation. Linear approximation of the real GMSK signal has to be performed in order to apply blind equalization. It is of interest to determine if the input sequence resulting from linearisation and the derotation in the receiver is white, which is a key assumption in many blind equalization algorithms. We show that the whiteness property is preserved. We make a comparison among three blind algorithms: two fractionally spaced and one based on baud-rate HOS. The simulation results indicate that blind equalization performs well and the algorithms have potential as a feasible solution to channel tracking in EDGE systems.