The Shadow Cluster Concept for Resource Estimation and Call Admission in Wireless ATM Networks

The Shadow Cluster concept is a novel idea which can be used to estimate future resource requirements and to perform call admission decisions in wireless networks. Shadow clusters can be used to determine if a new call should be admitted to a wireless network based on the call's requirements and local traac conditions. The shadow cluster concept can especially be useful in wireless ATM networks with micro/nano-cellular architectures where service will be provided to users with diverse Quality of Service (QoS) requirements. The framework of a shadow cluster system is completely distributed , and can be viewed as a message system where mobile terminals inform the base stations in their neighborhood about their requirements, position, and movement parameters. With this information , base stations project future demands, reserve resources accordingly, and admit only those calls that can be supported adequately. In this paper, it is shown how base stations: 1) determine the probabilities that a mobile terminal will be active in other cells at future times, 2) deene and maintain shadow clusters by using probabilistic information on the future position of their mobiles with active calls, and 3) predict resource demands based on shadow cluster information. In addition , a call admission algorithm is introduced, which uses current traac and utilization conditions, as well as the amount of resources and maximum allowable \dropping probability" being requested.