Adaptive channel assignment for different types of traffic in DS-CDMA cellular systems

Abstract

The link capacity of DS-CDMA cellular systems is limited by the interference contained in the link. This link interference is affected by many environment factors and thus the link capacity varies with the environment. Since link capacity changes with the varying interference and different traffic types mutually interfere with each other, it is difficult to use link capacity efficiently. Static channel assignment (SCA) based on fixed link capacity is inefficient for DS-CDMA cellular systems. To improve system capacity, channel assignments need to be adapted to variations in interference. In this paper, we propose an adaptive channel assignment (ACA) for different types of traffic. The proposed ACA is based on the reverse link power received at the base station and is adaptable to dynamically varying environments. It consists of two schemes: nonprioritized and prioritized. In the nonprioritized scheme, there is no difference in channel assignments between calls. In the prioritized scheme, however, the number of nonpriority calls acceptable is limited. In both schemes, a channel is assigned if the link power after assigning the channel is less than the power allowed in the link. The performance is evaluated in terms of link capacity and service grade. Utilizing the proposed algorithm yields more link capacity than using SCA in such environment changes as nonhomogeneous traffic load or varying path loss. Service grade is also improved by properly limiting the number of nonpriority channels.