Wireless Ad Hoc and Sensor Networks

4Admission Controller Design for High-SpeedNetworks: A Hybrid System ApproachIn the previous chapter, congestion control for ATM and the Internet wasdiscussed. In many applications, congestion control alone is not sufficientunless some sort of admission control is employed. In this chapter, we usethe congestion control scheme for the development of admission control.4.1 IntroductionHigh-speed networks supporting multimedia services are expected to becapable of handling bursty traffic and satisfying their various quality ofservice (QoS) and bandwidth requirements. Asynchronous transfer mode(ATM), a high-speed network pipe, is one of the key technologies forintegrating broadband multimedia services (B-ISDN) in heterogeneousnetworks, where multimedia applications consisting of data, video, andvoice sources transmit information (Lakshman et al. 1999, Jain 1996, Liewand Yin 1998). Owing to broadband traffic pattern uncertainties andunpredictable statistical fluctuations in network traffic, bandwidth managementand traffic control in high-speed networks pose new challengesand create difficulties. Therefore, a high-speed network must have anappropriate admission control (AC) scheme, not only to maintain QoS forexisting sources but also to achieve high network utilization by properlyadmitting new traffic. This chapter discusses an admission controllerscheme based on a hybrid system theory. The performance of the proposedscheme, though it is evaluated using cells, is applicable even forpacket-based networks. For instance, an ATM provides services to sourceswith different traffic characteristics by statistically multiplexing cells offixed-length packets of 53 B length. As a result, we have used packets/cells interchangeably.Conventional AC schemes (Bae and Suda 1991, Gurin et al. 1991, Jaminet al. 1997) that utilize either capacity estimation or buffer thresholdssuffer from fundamental limitations, such as the requirement of inputtraffic characteristics. An AC scheme must be dynamic in terms of147