Investigation of the Distributed Antenna Scheme for Multi-cell Environment in TDD-CDMA Systems

摘要

In this paper, both uplink (UL) and downlink (DL) performances are investigated for the TDD-CDMA system when employing the distributed antenna (DA) technology in the Macro multi-cell scenarios. In UL, both the DA and the multi-user detection (MUD) themes can suppress the interference and improve the capacity. Even the simple DA structure (called fixed DAS) can provide a high macro-diversity gain. Meanwhile, MUD technique is adopted to mitigate the intra-cell interference. In our work, the performance improvement due to DA and MUD are evaluated and compared. In order to improve the DL capacity, the advanced DL transmission mechanism, based on the virtual cell (called virtual DAS), is proposed. An advanced TDD-CDMA static system simulator for DA is built, and the simulation results show that both the capacity and coverage gain in UL are significant due to the receiving diversity gain sourced by the DA. In addition, the UL performance gain is related to the antenna element number and the MUD factor. However, in DL, due to the huge adjacent antenna's interference, the fixed DAS can't provide any capacity and coverage gain. The proposed virtual DAS provides higher capacity gain and wider coverage range than the fixed DAS does.