Orthogonal Frequency Division Multiplexing (OFDM) and Orthogonal Frequency Division Multiple Access (OFDMA) are modulation techniques that are deployed in various communications standards in today’s communication technology. The reason for their selection is the multitude of advantages that they offer over other modulation techniques that meet the increasing demands on high data rate communications. Consequently, this necessitates the need to devise mitigation methods for various impairments that accompany the implementation of OFDM and OFDMA.
This thesis focuses on the oscillator phase noise and its mitigation in uplink OFDMA systems to achieve a better overall system performance in terms of transceiver Bit-Error-Rate (BER). In OFDMA systems, the unequal uplink power levels of each user acts as a catalyst for the phase noise induced spreading effect that users with a higher power have on users with a lower one. This spreading effect is named Inter-User Interference (IUI). The simulation results depict the performance of various phase noise mitigation methods as a function of different received powers and phase noise levels in the uplink case for a user in an OFDMA symbol. The devised IUI itigation method achieves a significant gain over the conventional methods of phase noise mitigation which do not take into account the effect of the IUI.