Analysis of Interference on OFDM Mobile Communication Systems for Coexistence of Multiple Systems

Abstract

Orthogonal frequency division multiplexing systems are widely used as next generation mobile communication (NGMC) such as long term evolution (LTE) and worldwide interoperability for microwave access (WiMAX). NGMC systems require wider system bandwidths than existing systems to support higher data rates, therefore NGMC must share the limited frequency resource with other systems. OFDM systems support two duplex modes, frequency division duplexing (FDD) and time division duplexing (TDD). The FDD system has two separate frequency bands for downlink (DL) and uplink (UL). In contrast, the TDD system uses different time periods for DL and UL within the allocated frequency bands. The FDD and TDD systems are likely to be employed in same geographical areas and adjacent frequency bands. This causes adjacent channel interference (ACI).In this thesis, the possible interference problems between the coexisting two FDD systems and FDD DL and TDD systems were investigated. System level simulations were performed to calculated throughput losses according to adjacent channel interference ratio (ACIR). This result will be useful to decrease the throughput loss of coexisting OFDM systems.