Adaptive equalization of WACS in time-dispersive, fading, multipath channels

WACS (Wireless Access Communications Systems) developed by Bellcore is the basis of a proposed PCS standard in the 2 GHz emerging technology band in United States. WACS is ideally suited for indoor applications. It is generally known that operation in outdoor, large cell environments will require suitable receiver techniques to combat the effects of time-dispersive (delay-spread), fading, multipath channels. The authors study the effectiveness of down-link adaptive equalization for improving the performance of WACS for outdoor applications. A discussion on decision feedback equalization with different adaptation algorithms such as least mean squares (LMS) methods and recursive least squares (RLS) methods are provided. Joint Technical Committee (JTC) of Committee T1 and TIA in United States has developed comprehensive RF channel models to represent typical indoor and outdoor channel conditions. Simulation results of applying adaptive equalization to WACS with the JTC outdoor RF channel models are presented. The results indicate that with a judicious choice of adaptation algorithm, it is possible to obtain adequate performance in outdoor channels while remaining within the bounds of reasonable complexity