Evaluation of performance enhancement on CRLB of CAF under multiple emitters

A method of enhancing performance is described on the Cramer–Rao lower bound (CRLB) of time difference of arrival (TDOA) and frequency difference of arrival (FDOA) measurements under multiple emitters. The TDOA and FDOA measurements between two receivers can be simultaneously estimated by using the cross ambiguity function (CAF). However, in the case of multiple emitters, these measurements are contaminated by the inter-symbol interferences (ISIs) which deteriorate the estimation quality. Therefore, it is required to reduce the effect of ISIs for enhancing the performance prior to calculating CAF. For separating the interference signals from the desired signal, we select the angle of arrival estimation algorithm with multiple array antennas. The performance of the estimator can be expressed as CRLB and the separation probability is calculated by employing the locally most powerful test. From the numerical evaluation results, it was observed that the performance could be significantly improved especially for the situation under heavy ISIs.