Performance of an Uplink OFDMA System Using Subcarrier Allocation

Abstract

OFDMA (Orthogonal Frequency Division Multiple Access) suffers from destruction of orthogonility if a channel betweenthe mobile user and a base station is rapidly time varying. This channel between the mobile user and a base station is called an Uplink-OFDMA. The OFDMA uplink resource allocation undergoes from Inter carrier interference (ICI), multiuser interference (MUI) if a nearby subcarrier is assigned to different user, high peak to average power ratio (PAPR) and high bit error rate (BER).This results in performance degradation. In order to provide a significant improvement in performance, a practical OFDMA system detection is required. The proposed system consists of a new sub-carrier allocation method using a successive interfer ence cancelation (SIC) detector at the receiver side. The proposed system is designed and simulated using MATLAB tool. Simulation results show that the proposed subcarrier allocation and ―Interleaved Aǁ allocation method has an average Bit errorprobability of 10 -0.5 and 10-0.2 respectively. Thus Average Bit error probability of around 32% is reduced compared to the ―Interleaved Aǁallocation method. Further, simulations also demonstrate a gradual decrease in MUI power from -15db to -20db for interleaved al location and subcarrier allocation method respectively