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Chapter 6OPTIMISATION OF CRAALGORITHMS USINGADAPTIVE CSA6.1 IntroductionContention resolution algorithms (CRA) define the set of rules used to resolvecollisions. They play a vital role in the performance of a multi-access reservationprotocol. This is because the faster they resolve collisions, the lower the access delaywill be and the higher the system throughput will become. Initially, CRAs gained muchinterest in the early 1970s for usage in the transmission of radio packets, and especiallyduring the development of the ALOHANET project [1]. Two major candidates weredefined, ALOHA-based algorithms like ‘exponential backoff and p-persistence’ andsplitting tree algorithm, as reported in Section 1.2.3.2. Since then, much research hasbeen devoted to devising efficient contention resolution mechanisms for multi-accessmedia for Local Area Networks (LANs), Metropolitan Area Networks (MAN), satellitenetworks, radio networks and CATV networks [41].In this chapter, we study in detail performance, optimisation and implementation issuesfor the contention resolution algorithm adopted by the DVB/DAVIC protocol. We payparticular attention to the dynamics and operation of the exponential backoff algorithmand the splitting tree algorithm. Furthermore, special emphasis is paid to the design ofadaptive mechanisms, called Contention Slot Allocators (CSA), which dynamicallyadjust the bandwidth used for contention access, significantly increasing the systemperformance when different bounds are considered.6-1