Analytical approach to multiple memoryless backoff contention analysis

Abstract

The paper addresses the performance analysis of the multiple memoryless backoff contention in slotted-CSMA protocols. By multiple memoryless backoff (MMB) system we define a heterogeneous random access protocol when the contending stations sample from different numbers of contention slots, and the sampled backoff times are cancelled when the transmission is detected in the channel. The MMB contention occurs in practice in many random access networks usually due to different history of collisions experienced by particular stations (e.g. in binary exponential backoff in CSMA/CD IEEE 802.3, or in linear backoff used in predictive p-CSMA in LonTalk (ISO/IEC 14908). The MMB provides unequal allocation of bandwidth among the stations, and thus introduces unfairness in channel access. The paper contains derivations of analytical formulae for probabilities of successful and successful transmissions needed to determine throughput and mean access delay. Finally, sample numerical results for multiple memoryless backoff network are presented.