Generalized Analysis for the Evaluation of Search Strategy Effects on PN Acquisition Performance

Pseudonoise (PN) coding may be incorporated into the signal structure of a communication system for a variety of reasons. Once present, the PN code must be appropriately acquired before it can be tracked by the receiver. Toward this end various acquisition schemes have been proposed. These schemes include combinations of predetection/postdetection processing and code search strategies. With regard to the latter, a uniform search over the entire code uncertainty region would be undertaken in the absence of a priori epoch information. In the presence of such information a more sophisticated scheme, which may generally be termed an "expanding window search," would tend to reduce acquisition time. The present paper focuses on uniform and expanding window search strategies with the goal of analytically developing the PN acquisition time statistics as functions of salient system parameters such as predetection SNR, detection and false alarm probabilities, false alarm penalty time, and a priori information on epoch location. The significance of this analysis is its general applicability to arbitrary postdetection processing schemes-e.g., fixed dwell and sequential detection. Computed performance results account for the above salient parameters, wherein sequential detection is employed in conjunction with uniform and selected expanding window search strategies. Performance curves demonstrate the utility of the analysis and provide intuitive insight into performance sensitivity to search strategy.