Medium Access Control Protocols With Memory

TL;DR

This paper introduces a framework for designing and analyzing memory-based MAC protocols in slotted networks, showing how protocols with finite memory can approach optimal throughput and adapt to network conditions.

Contribution

It provides a general framework for evaluating memory-based MAC protocols, demonstrating that protocols with finite memory can achieve near-optimal throughput and analyzing their performance with Markov models.

Findings

Protocols with (N-1)-slot memory can reach TDMA performance after a transient period.

Protocols with 1-slot memory can achieve near 100% throughput with high delay.

The framework applies to wireless LANs, enhancing MAC protocol design.

Abstract

Many existing medium access control (MAC) protocols utilize past information (e.g., the results of transmission attempts) to adjust the transmission parameters of users. This paper provides a general framework to express and evaluate distributed MAC protocols utilizing a finite length of memory for a given form of feedback information. We define protocols with memory in the context of a slotted random access network with saturated arrivals. We introduce two performance metrics, throughput and average delay, and formulate the problem of finding an optimal protocol. We first show that a TDMA outcome, which is the best outcome in the considered scenario, can be obtained after a transient period by a protocol with (N-1)-slot memory, where N is the total number of users. Next, we analyze the performance of protocols with 1-slot memory using a Markov chain and numerical methods. Protocols with 1-slot memory can achieve throughput arbitrarily close to 1 (i.e., 100% channel utilization) at the expense of large average delay, by correlating successful users in two consecutive slots. Finally, we apply our framework to wireless local area networks.