Array signal processing, is a part of signal processing that uses sensors that are organized in patterns, or arrays, to detect signals and to determine information about them. Accurate estimation of a signal direction of arrival (DOA) has received considerable attention in communication and radar systems of commercial and military applications. Radar, sonar, seismology, and mobile communication are a few examples of the many possible applications. For example, in defence application, it is important to identify the direction of a possible threat. One example of commercial application is to identify the direction of an emergency cell phone call in order to dispatch a rescue team to the proper location. Thus the need for precise estimation of parameters of the signal sources impinging onto the array, like direction-of-arrival (DOA) or time-of-arrival (TOA), can be recovered from the incident source waveforms.