Modified Cramer-Rao bound of parameter estimation for single-channel mixtures of adjacent-frequency signals

Present research on the bounds of parameter estimation performance is focused solely on single-source signals; thus, no benchmark for such bounds of mixed signals is currently available. For the case of a single-channel mixture of adjacent-frequency digitally modulated source signals, the modified Cramer–Rao bounds (MCRBs) of parameter estimation for frequency offsets, carrier phases, and time delays have been derived. A detailed comparison among the MCRBs of jointly estimating different parameters set is then conducted. Moreover, comparisons between maximum likelihood estimators and MCRBs, true Cramer–Rao bounds and MCRBs have been conducted, through theoretical analysis and numerical simulation.