Effects Of Base Station Power Control And Soft Handoff On The Outage And Capacity In The Forward Link Of CDMA Systems

This thesis focuses on the capacity analysis of the forward link of code division multiple access (CDMA) systems by characterizing the base station (BS) power distribution. With the rapid growth of data and multi-media traffic, the forward link becomes the system bottleneck. How to design an efficient call admission algorithm in the forward link to effectively use the limited base station power while guaranteeing certain quality of service is important to increase the forward link capacity. To effectively use the limited BS power, we need to understand the BS power distribution given a certain traffic pattern. However, the characterization of the BS power in the forward link has not been adequately addressed in the literature and the limit of the BS power on the capacity has not been fully studied. By taking into consideration of channel characteristics and system parameters, such as the network traffic pattern, call admission algorithm, power control strategies, and soft handoff approach, we characterize the BS power distribution and obtain a closed-form expression of the forward link capacity. Furthermore, previous work studying the forward link performance assumes equal BS power throughout the system and obtains a static capacity without considering the correlation and interactional relation among BS powers, which is rarely true in the real CDMA systems. By further considering the interaction among BS powers, we introduce an iterative process to determine the dynamic forward link capacity. From the system engineering aspects, our research can provide an analytical framework to facilitate the design and benchmark of CDMA networks compared to pure computer simulations. The models established in our research also provide an accurate estimation of the network capacity. Since the air interface of future networks or networks being deployed recently, such as wide-band CDMA (WCDMA), CDMA 2000, and Universal Mobile Telecommunication Services (UMTS), is CDMA based, we are expecting that our research is useful to design call admission algorithms in wireless systems.