Broadcasting in Time-Division Duplexing: A Random Linear Network Coding Approach

TL;DR

This paper analyzes a random linear network coding scheme for broadcasting over TDD channels, demonstrating improved mean completion times and proposing a heuristic for efficient transmission stopping criteria.

Contribution

It introduces a novel coding and stopping strategy for TDD broadcast channels, with analytical bounds and a heuristic that reduces search complexity.

Findings

Outperforms optimal scheduling in mean completion time

Provides bounds on acknowledgment waiting time

Proposes a near-optimal heuristic for transmission stopping

Abstract

We study random linear network coding for broadcasting in time division duplexing channels. We assume a packet erasure channel with nodes that cannot transmit and receive information simultaneously. The sender transmits coded data packets back-to-back before stopping to wait for the receivers to acknowledge the number of degrees of freedom, if any, that are required to decode correctly the information. We study the mean time to complete the transmission of a block of packets to all receivers. We also present a bound on the number of stops to wait for acknowledgement in order to complete transmission with probability at least $1-\epsilon$, for any $\epsilon>0$. We present analysis and numerical results showing that our scheme outperforms optimal scheduling policies for broadcast, in terms of the mean completion time. We provide a simple heuristic to compute the number of coded packets to be sent before stopping that achieves close to optimal performance with the advantage of a considerable reduction in the search time.