Adaptive DFE algorithms for IS-136 based TDMA cellular phones

Optimum detection in randomly time-varying channels requires an efficient adaptive receiver structure. The complexity of signal processing in the receiver is limited by the amount of processing power and power consumption of the receiver. Therefore, efficiency and convergence of adaptive matched filtering and equalization techniques are very important. We extend common results in tracking theory for system identification to the equalization case for systems with short impulse response. Unlike in system identification where a steady-state error energy is minimized, the optimization criterion here is the minimum of the BER. However, they are related by a monotone function and therefore minimizing the BER is equivalent to minimizing the steady-state-error energy. Optimum parameters for LMS as well as RLS algorithms are derived and simulation results indicate that under the conditions defined in the TDMA standards and small delay spread, the performance of the two methods is comparable