Closed-Form Expression of Stochastic CRB for Mixed Near-Field and Far-Field Sources in Multipath Propagation Environments

In recent years, the source localization has had an increased interest in regard to the presence of mixed near-field sources (NFSs) and far-field sources (FFSs). The problem of localization of multiple mixed NFSs and FFSs, including uncorrelated, partially correlated, and coherent signals, has not been studied. In this letter, for the first time, the mathematical model of received signals is introduced in the presence of mixed sources for complex multipath environments. Then, a closed-form expression is extracted for the stochastic Cramér-Rao bound associated with the above scenario.