Bandwidth-constrained distributed estimation for wireless sensor networks - Part II: Unknown probability density function

Wireless sensor networks (WSNs) deployed to perform surveillance and monitoring tasks have to operate under stringent energy and bandwidth limitations. These motivate well distributed estimation scenarios where sensors quantize and transmit only one, or a few bits per observation, for use in forming parameter estimators of interest. In a companion paper, we developed algorithms and studied interesting tradeoffs that emerge even in the simplest distributed setup of estimating a scalar location parameter in the presence of zero-mean additive white Gaussian noise of known variance. Herein, we derive distributed estimators based on binary observations along with their fundamental error-variance limits for more pragmatic signal models: i) known univariate but generally non-Gaussian noise probability density functions (pdfs); ii) known noise pdfs with a finite number of unknown parameters; iii) completely unknown noise pdfs; and iv) practical generalizations to multivariate and possibly correlated pdfs. Estimators utilizing either independent or colored binary observations are developed and analyzed. Corroborating simulations present comparisons with the clairvoyant sample-mean estimator based on unquantized sensor observations, and include a motivating application entailing distributed parameter estimation where a WSN is used for habitat monitoring.