The rapidly increasing demand for mobile broadband traffic drives the need for even more capacity from cellular networks. Multiple Input Multiple Output (MIMO) technology is a key element of modern wireless communication standard including Long Term Evolution (LTE) and WiMAX. MIMO systems are used to improve the robustness of data transmission, to increase data rate, to improve capacity and other aspects of network performance. In the absence of line of sight (LOS) between the mobile receiver station (MS) and the base station (BS), the localization of the BS is very important. 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. Yet, they are not capable of distinguish and identify which one is the direction of the desired user. In this paper, a reference signal is known by the transmitter and the receiver is proposed to identify which one of the estimated DOAs is the direction of the desired user in the cell. With the aid of such reference signal and applying the correlation concept, the DOA algorithms
can distinguish the direction of the desired signal from the others. This concept was applied to the MUltiple SIgnal Classification (MUSIC), ROOT MUSIC, and Minimum  Variance Distortion less Response (MVDR) algorithms. Moreover, the Affine Projection Algorithm (APA) is classified as a fast adaptive filter was implemented in this paper to enhance the accuracy of the estimated direction and to form a beam towards the desired user and nulls towards interferes. Extensive simulation results assure that in the presence of the proposed reference signal, the DOAs algorithms can identify the direction of the desired user with high accuracy and resolution.