An Integrated Evaluation of Qualities of Wired and Wireless Channels with Consideration of Soft Handoff in CDMA Cellular Systems

In CDMA mobile cellular systems, wireless quality is improved by soft handoff techniques. However, it requires to hold multiple channels of cells, which is likely to increase call blocking at wired channels. It is therefore necessary to consider the entire system including the wired and wireless portions of systems for investigating an effectiveness of the soft handoff. The effect of interference power from mobile stations that are not in the soft handoff is also important to be investigated. In this paper, we propose an integrated evaluation method of qualities of wired and wireless channels, and gives an analysis method which can incorporate the above-mentioned problems. In the analysis, we model three-way soft handoff which has not been considered in past researches. We also show the effect of a call admission control on wireless quality. Moreover, we investigate the effect of soft handoff in IMT-2000. In IMT-2000, the demand for data communication would be increased according to an explosive demand on the Internet accesses. It means that the performance of the download link would become more important. A soft handoff technique is effective on the uplink in general because it suppresses the interference power from MSs. However, more than one BS must send signals for MSs during the soft handoff state. It implies that the interference power for downlink is also increased. Taking those facts in mind, we investigate the soft handoff in IMT-2000 through simulation studies. Our finding is that an improvement by soft handoff technique can be found, but it depends on