Capacity effects of the WCDMA 2.5 GHz DL due to UE-UE interference

Abstract

This paper derives the capacity reduction of WCDMA downlink due to mobile-to-mobile (UE-UE) interference. The assumed frequency scenario is the FDD UL/DL + additional FDD DL operation at 2.5 GHz band identified by ITU-WP8F. The developed downlink capacity model takes into account the average interference from closely located, spectrally adjacent mobiles. The model assumes non-uniform user distribution. The interference coupling due to basestation-tobasestation (BS-BS) interference has been introduced, as well. Similar calculation method can be utilized when computing the interference effects of closely located, independent TDD systems. The suggested model has been demonstrated with numerical examples. The recognition of these interference phenomenas is very important since unlike the BS-UE interference between operators the UE-UE interference is difficult or even impossible to eliminate with the network planning methods. Results indicate that the effect of user distribution, adjacent network loading, UE-UE propagation, cell sizes and the BS-BS isolation have to be taken into account when comparing the performance of radio systems where the UE-UE interference is present.