Cramer Rao Bounds for Primary User Localization Using Hybrid Toa/doa Technique in Cognitive Radios

Cognitive Radio (CR) is of great interest to technologists because of significantly increasing the spectrum efficiency. The Secondary user (SU) which is the unlicensed user must constantly study the actions of Primary user (PU), which is the licensed user. The location information of PU can enable several key functions of CR networks, such as aiding spectrum policy enforcement, intelligent location aware routing, and better spatial temporal sensing. Time of Arrival, Directions of Arrival and Received Signal Strength are three categories of research that is being done previously in the field of passive localization. These categories are done based on how the sensors obtain location estimation and on the type of measurements shared between the sensors. Cramer-rao bound establishes the lower limit on how much information about an unknown probability distribution parameter can a set of measurement carries. In this paper we obtain the Cramer-rao bounds for a novel hybrid Direction of arrival (DOA)/Time of arrival (TOA) based algorithm in cognitive radios networks and the performance is analyzed and compared for various primary user location estimation techniques such as RSS-CRB, Joint-CRB optimal, and Joint-CRB music.