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

The link capacity of DS-CDMA cellular systems is limited by the interferenc e contained in the link. This link interference is affected by many environ ment factors and thus the link capacity varies with the environment. Since link capacity changes with the varying interference and different traffic t ypes mutually interfere with each other, it is difficult to use link capaci ty efficiently. Static channel assignment (SCA) based on fixed link capacit y is inefficient for DS-CDMA cellular systems. To improve system capacity, channel assignments need to be adapted to variations in interference. In th is paper, we propose an adaptive channel assignment (ACA) for different typ es 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 nonprior itized scheme, there is no difference in channel assignments between calls. In the prioritized scheme, however, the number of nonpriority calls accept able is limited. In both schemes, a channel is assigned if the link power a fter assigning the channel is less than the power allowed in the link. The performance is evaluated in terms of link capacity and service grade. Utili zing the proposed algorithm yields more link capacity than using SCA in suc h environment changes as nonhomogeneous traffic load or varying path loss. Service grade is also improved by properly limiting the number of nonpriori ty channels.