Contention Control in Multi-access Resource Systems

All wireless communications, including radio, satellite, and mobile systems, as well as wired broadcast networks, require mechanisms for resolving contention. Strategies for allocation of shared bandwidth among competing users have evolved from no policy (e.g., ham radio, where strength of signal determines access), to complex control and encoding schemes, where access is provided based on varying scheduling goals such as throughput, priorities, bounded waits, and fairness (i.e., DQDB). As wireless media become more heavily used, mechanisms that prevent contention (e.g. TDMA) at a significant cost of bandwidth are balanced against mechanisms that allow contention to occur, but, at their own cost, recover from it (e.g., IEEE 802.11). We review the various types of protocols for contention control in multi-access resource systems to aid in the understanding of why they have evolved and under which conditions they have been successful.