Variable-gain Cdma Communication System And Macrodiversity Cdma Communication System Capacity

In this dissertation, researches on performance of variable spreading gain CDMA with imperfect power control and uplink capacity analysis of limited maximal ratio combining macrodiversity in spread spectrum radio networks are carried out.The main originality in this paper can be summarized as below.1. Performance of Variable Spreading Gain CDMA with Imperfect Power Control.In this chapter, we analyze the capacity of VSG-CDMA system under imperfect power control in a multi-cell environment with multiple types of users. A simple and practical admission criterion is derived relating the intra-cell interference and other-cell interference The admission criterion can be applied to uneven distribution of mobile in the hot spot cell. Due to varying radio channel, the admission bound is variable rather than a fixed boundary. The probability distribution of under imperfect control for multiple service is deduced. The link failure probability is also formulated by utlizing a simple and accurate approximation to incorporate the effect of imperfect power control. The adverse effect of power control imperfection to the capacity has also been analyzed.2. Uplink Capacity analysis of limited maximal ratio combining macrodiversity in spread spectrum radio networksIn this chapter, a more practical case of limited maximal ratio combining macrodiversity (MMRC), mobile's signal only received by a limited number of nearest base stations, in a CDMA system was studied. The analysis shows that limited macrodiversity can provide more capacity than selection combining. Moreover, although the diversity degree is limited, the interference level is closed to ideal case (ie., signal can received by all base stations) and then capacity closed to isolated cell because of propagation attenuation especially in lower shadowing conditions.