Error reduction of range estimates in multipath environments

A reduction in error is obtained for estimates of range computed in a multipath environment. A good estimation technique for this problem typically involves exploiting the multipath interference, that is, analyzing each received signal reflection to improve the estimate. Under certain conditions, however, the errors in multipath estimates can be quite large. We compute the Cramer-Rao bounds for an example satisfying these conditions to demonstrate this phenomenon. We propose a modification to the original signal model which better represents the received signals. While the modified model does introduce a bias error, we provide a suitable estimate of the bias error so that a complete error anaylsis of the modified model is possible. The total error (noise error plus bias error) for the modified model is computed for an example and compares favorably with the error obtained via the original signal model.