How CSMA/CA With Deferral Affects Performance and Dynamics in Power-Line Communications

TL;DR

This paper develops a new performance model for power-line communication networks using CSMA/CA with deferral, addressing the limitations of previous models by accounting for station coupling and analyzing both steady-state and transient behaviors.

Contribution

It introduces a novel model for IEEE 1901 that captures the effects of deferral counters, improving accuracy over existing decoupling-based models.

Findings

The new model accurately predicts performance across various configurations.

Simulation results confirm the model's superiority over traditional decoupling assumptions.

Transient dynamics are significantly influenced by the deferral mechanism.

Abstract

Power-line communications (PLC) are becoming a key component in home networking, because they provide easy and high-throughput connectivity. The dominant MAC protocol for high data-rate PLC, the IEEE 1901, employs a CSMA/CA mechanism similar to the backoff process of 802.11. Existing performance evaluation studies of this protocol assume that the backoff processes of the stations are independent (the so-called decoupling assumption). However, in contrast to 802.11, 1901 stations can change their state after sensing the medium busy, which is regulated by the so-called deferral counter. This mechanism introduces strong coupling between the stations and, as a result, makes existing analyses inaccurate. In this paper, we propose a performance model for 1901, which does not rely on the decoupling assumption. We prove that our model admits a unique solution for a wide range of configurations and confirm the accuracy of the model using simulations. Our results show that we outperform current models based on the decoupling assumption. In addition to evaluating the performance in steady state, we further study the transient dynamics of 1901, which is also affected by the deferral counter.