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 mul-tipath interference, that is, analyzing each received signal reeection to improve the estimate. Under certain conditions , however, the errors in multipath estimates can be quite large. We compute the Cram er-Rao bounds for an example satisfying these conditions to demonstrate this phenomenon. We propose a modiication to the original signal model which better represents the received signals. While the modiied model does introduce a bias error, we provide a suitable estimate of the bias error so that a complete error anaylsis of the modiied model is possible. The total error (noise error plus bias error) for the modiied model is computed for an example and compares favorably with the error obtained via the original signal model.