Interference considerations for the time division duplex mode of the UMTS terrestrial radio access

The air interface of the UR ITS Terrestrial Radio Access (UTRA) covers both a frequency division duplex (FDD) part for the paired bands and a time div ision duplex (TDD) part for the unpaired bands of the UMTS spectrum. Univer sal Mobile Telecommunication System (UMTS) is the 3rd-generation mobile com munication system. This paper presents an interference evaluation of the UT RA TDD. Since both uplink and downlink share the same frequency in TDD, the signals of the 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. The interference bet ween uplink and downlink is evaluated by system simulations in this paper. Synchronization and coordination requirements of UTRA TDD are evaluated bas ed on the results.