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The Multistage CM Array

Richard Gooch
Applied Signal Technology
160 Sobrante Way
Sunnyvale, CA 94086
email: rpg@appsig.com

Abstract The multistage constant modulus (CM) array is a blind adaptive beamformer designed to separate multiple cochannel signals in environments where heavy frequency reusage is employed (e.g., wireless mobile radio). It consists of a cascade of multiple stages of CM arrays and adaptive signal cancelers. The CM array in each stage is used to isolate one of the cochannel signals. The signal canceler is used to remove the captured signal prior to processing by a next stage and to provide an estimate of the direction vector of the captured source. This presentation gives an overview of the multistage CM array and an analysis of its steady-stage behavior. The analysis is based on a Wiener model of convergence and the results are verified by computer simulation. A real-time hardware implementation is also presented along with a video demonstrating its operation in a cellular radio environment.



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