Impact of FDD/TDD co-existence on overall UMTS system performance

Interference and compatibility issues relating to coexistence of two duplexing modes in UMTS, FDD and TDD, are highlighted in this paper. Performance degradation due to co-existence is quantified by comparing with single system scenarios. It has been found that system performance depends on the loading of both FDD and TDD. Co-existence can be optimised when some compromise is observed. This optimal compromise has been derived in this paper, giving the maximum loading in one system when loading of another is known. BS/spl lrarr2/BS interference scenario is found to be most damaging and therefore, the distance between BSs of the two systems should be maximised.