Bruce D. Mueller

A comparison of nonlinear equalization methods for the US digital cellular system

Two forms of nonlinear equalization for the US digital cellular channel are considered. First, the decision feedback equalizer is examined. With the rapidly adapting recursive least squares algorithm, it is seen to adapt and track the channel with some error propagation problems. Second, the maximum likelihood sequence estimator (MLSE) with an adaptive channel estimator is developed. Simplifications are presented to reduce the complexity of the algorithm. An adaptive, predictive channel estimator is described which attempts to mitigate the effects of delay in the MLSE algorithm. Comparisons of performance and complexity are made.<<ETX>>

A parallel adaptive filter structure for digital mobile radio applications

A parallel adaptive filter structure is described which exploits characteristics of the error signal in adaptive algorithms to improve modem performance in a rapidly changing mobile radio environment. Examples which apply this technique to coherent detection, channel equalization, and automatic frequency control are given.