Network Coded Handover in IEEE 802.11

TL;DR

This paper introduces a network coded handover framework for WiFi networks, modeling and analyzing delay and transmission strategies to optimize handover timing between access points.

Contribution

It presents a novel model for IEEE 802.11 DCF with fixed contention window, extending to N-packet transmission and coded broadcast, and formulates optimal handover strategies using network coding.

Findings

Model accurately predicts transmission delays in WiFi handover scenarios.

Coded broadcast improves reliability over traditional unicast.

Optimal handover timing can be derived to minimize delay.

Abstract

We propose a network coded handover of a station moving between two IEEE 802.11 access points (AP). To address such novel proposed framework on a small cell WiFi to WiFi AP handoff, we propose a novel model for the Distributed Coordination Function (DCF) of the WiFi IEEE 802.11 with fixed average contention window. We provide a single packet tranmission model which has been extended to N-packets transmission models with and without fragmentation. We also model the N-packet transmission for the uncoded/coded packets broadcast in order to compare the IEEE 802.11 unreliable to reliable coded broadcast with ACK. We analyze the delay over all, unicast and broadcast transmissions, for the scenario considered with a topology with one WiFi AP before the handover. Capitalizing on the set of models and their corresponding mean completion times (delay), we analyze the performance of different mechanisms. Finally, we provide a novel formulation of the Network Coding on the Edge handover when the station is mobile allowing for the derivation of optimal transmission strategies that can define an optimal time, when to switch to the other AP.