Influence of Discontinuous Transmission and Power Control on the Average SIR and the Outage Probability of the Uplink of CDMA Systems

In this paper the impact of the voice activity detection process and the powercontrolsystem on the average signal-to-interference ratio (SIR) is investigatedconcerningthe uplink of a single cell code division multiple access (CDMA) based mobilecommunication system. In the literature lower bounds on the average SIR areoftenemployed. Here we show the applicability of such bounds. For this purpose theresultsobtained from these bounds are compared with results obtained fromsimulations.Especially, for a few number of subscribers the differences between the lowerboundand the exact values are significant. Furthermore, the variance of the SIR isinvestigated for different parameters. We found out that significantvariations occurwhich affect the outage probability. But, many authors often employ only theaverageSIR, e.g. for their capacity estimations. However, the variance of the SIR hasto betaken into consideration too.