Direction of Arrival algorithms for user identification in cellular networks

The Direction of Arrival (DOA) algorithms can estimate the incident angles of all the received signals impinging on the array. These algorithms give the DOAs of all the relevant signals of the user sources and interference sources. However, they are not capable of distinguish and identify which one is the direction of the desired user. In this paper, we propose to use a reference signal which is known by the transmitter and the receiver to identify which one of the estimated DOAs is the direction of the desired user in the cell. Using a reference signal and applying the correlation concept, the DOA algorithms can distinguish the desired signal from the others. Moreover, we implement the Affine Projection Algorithm (APA) to enhance the accuracy of the estimated direction and to form a beam towards the desired user and nulls towards the interferes. Our simulation results assure that, in the presence of the reference signal, the DOAs algorithms can identify the direction of the desired user with high accuracy and resolution. We have applied this concept to MUSIC, ROOT MUSIC, and ESPRIT algorithms.