Three Schemes for Wireless Coded Broadcast to Heterogeneous Users

TL;DR

This paper compares three wireless broadcast coding schemes—LT, growth, and chunked codes—for heterogeneous users with different demands and packet loss rates, highlighting the advantages of optimized LT codes especially with systematic phases.

Contribution

The study introduces optimized degree distributions for LT codes and provides a comparative analysis of three coding schemes for heterogeneous wireless broadcast scenarios.

Findings

Optimized LT codes outperform growth and chunked codes in delivery time.

Including a systematic phase benefits low-demand scenarios.

Coding is essential for high-demand, efficient delivery.

Abstract

We study and compare three coded schemes for single-server wireless broadcast of multiple description coded content to heterogeneous users. The users (sink nodes) demand different number of descriptions over links with different packet loss rates. The three coded schemes are based on the LT codes, growth codes, and randomized chunked codes. The schemes are compared on the basis of the total number of transmissions required to deliver the demands of all users, which we refer to as the server (source) delivery time. We design the degree distributions of LT codes by solving suitably defined linear optimization problems, and numerically characterize the achievable delivery time for different coding schemes. We find that including a systematic phase (uncoded transmission) is significantly beneficial for scenarios with low demands, and that coding is necessary for efficiently delivering high demands. Different demand and error rate scenarios may require very different coding schemes. Growth codes and chunked codes do not perform as well as optimized LT codes in the heterogeneous communication scenario.