Evaluation of interference between uplink and downlink in UTRA/TDD

An ideal TDD system offers high capacity, dynamic asymmetry between uplink and downlink and no coordination requirements between operators and base stations. This paper studies the performance of UTRA/TDD and how close to the ideal TDD system UTRA/TDD could be. Since both uplink and downlink share the same frequency in TDD, those two transmission directions can interfere with each other. This interference can occur between two mobile stations or between two base stations within one carrier or between two operators. This interference scenario is evaluated here. The results show that for UTRA/TDD operation dynamic channel allocation, synchronization of base stations and cooperation between the operators is preferred to obtain the maximum performance. The most difficult interference situations occur between base stations within one operator's band and between two operators if they are not synchronized.