Approximating Throughput and Packet Decoding Delay in Linear Network Coded Wireless Broadcast

TL;DR

This paper analyzes the performance of linear network coding in wireless broadcast systems, establishing relationships between throughput and decoding delay, and identifying which coding techniques can approximate these metrics effectively.

Contribution

It introduces approximation relations between throughput and decoding delay, proves equivalences, and assesses the effectiveness of various LNC techniques in approximating these metrics.

Findings

Strong throughput approximation implies strong APDD approximation.

Throughput-optimal LNC techniques can strongly approximate APDD.

Memoryless LNC techniques cannot strongly or weakly approximate throughput or APDD.

Abstract

In this paper, we study a wireless packet broadcast system that uses linear network coding (LNC) to help receivers recover data packets that are missing due to packet erasures. We study two intertwined performance metrics, namely throughput and average packet decoding delay (APDD) and establish strong/weak approximation relations based on whether the approximation holds for the performance of every receiver (strong) or for the average performance across all receivers (weak). We prove an equivalence between strong throughput approximation and strong APDD approximation. We prove that throughput-optimal LNC techniques can strongly approximate APDD, and partition-based LNC techniques may weakly approximate throughput. We also prove that memoryless LNC techniques, including instantly decodable network coding techniques, are not strong throughput and APDD approximation nor weak throughput approximation techniques.