MITIGATION OF INTER CELL INTERFERENCE IN MULTI CELL ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS SYSTEMS

Abstract

Orthogonal Frequency Division Multiple Access (OFDMA) is the multi-user version of Orthogonal Frequency Division Multiplexing (OFDM). Due to the orthogonality of the sub-carriers, the interference between the sub-carriers is eliminated. However in multi-cell OFDMA system, if same sub-carriers are assigned to different users in neighboring cells, then inter-cell interference (ICI) occurs. ICI is more prominent for the users at cell boundaries due to which the cell edge users experience lower data rates compared to the users close to the base stations. During the thesis work, a dynamic radio resource allocation algorithm has been designed for mitigation of ICI. This algorithm assigns sub channels to the users and their transmission power based on the user location and sub channel assignment information from neighboring cells. The performance of Reuse 1, Reuse 3, Partial Frequency Reuse (PFR), Soft Frequency Reuse (SFR) and the dynamic resource allocation algorithm have been analyzed on the basis of change in Signal to Interference and Noise Ratio (SINR) values, system Bit Error Rate (BER), bandwidth efficiency and channel capacity with increase in distance of User Equipment (UE) from the center of cell. The dynamic resource allocation algorithm provides satisfactory levels of SINR values throughout the cell region and also maintains higher system capacity for users as compared to other resource allocation techniques.