Ambiguity function and Cramer-Rao bounds for universal mobile telecommunications system-based passive coherent location systems

The concerns are with the calculation of monostatic and bistatic ambiguity function (AF) of a quadrature phase shift keying (QPSK) signal where the pulses are shaped with a root raised cosine (RRC) filter. The monostatic and bistatic modified Craméŕ-Rao lower bounds (MCRLBs) for the estimation of target range and velocity are also derived and analysed. The QPSK modulation is used in the downlink of a universal mobile telecommunications system (UMTS) base station, hence the results of our analysis provide a useful tool to asses the performance of a passive coherent location (PCL) system where the non-co-operative transmitter of opportunity is a UMTS base station. The actual growing coverage of UMTS signals on the international territory makes multistatic radar configuration feasible, therefore these results can also be exploited for the dynamical selection of the transmitter in a multistatic radar system where multiple UMTS base stations are used.