Multiple Signals Direction Finding of IoT Devices Through Improved Correlative Interferometer Using Directional Elements

Due to the increasing number of Internet of Things (IoT) devices in smart cities and the necessity to monitor or locate them, this paper presents a direction finding (DF) method based on the popular correlative interferometer (CI) method using a uniform circular array (UCA) with directional elements and an extra central omnidirectional element as a reference. Unlike the conventional CI (CCI) method, the proposed method can estimate several coherent or incoherent sparse sources at a certain frequency by defining a new cost function based on gains of UCA elements. Moreover, the speed and accuracy of the proposed algorithm are improved by using a proposed new method for search region reduction (SRR) in the lookup table based on power measurement in each element and the successive interference cancellation (SIC) concept. The simulation results show the performance improvement and accuracy of direction of arrival (DOA) estimation using the proposed method in several coherent or incoherent signal sources and multipath environment. In addition, the results show that the proposed method along with SRR can suppress the false peaks.