This document describes a study on adaptive network coding schemes for broadband wireless access networks. It analyzes random network coding (RNC) and systematic network coding (SNC) decoding probabilities and selects SNC for developing an adaptive scheme called Frame-by-frame Adaptive Systematic Network Coding (FASNC). FASNC dynamically uses either Modified Systematic Network Coding (M-SNC) or Mixed Generation Coding (MGC) depending on per-frame network constraints. An analytical model is developed to evaluate the mean decoding delay and mean goodput of the proposed FASNC scheme, with results matching computer simulations.

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ADAPTIVE NETWORK CODING FOR BROADBAND WIRELESS
ACCESS NETWORKS
ABSTRACT:
Broadband wireless access (BWA) networks, such as LTE and WiMAX, are inherently lossy due
to wireless medium unreliability. Although the Hybrid Automatic Repeat reQuest (HARQ) errorcontrol method recovers from packet loss, it has low transmission efficiency and is unsuitable for
delay-sensitive applications. Alternatively, network coding techniques improve the throughput of
wireless networks, but incur significant overhead and ignore network constraints such as
Medium Access Control (MAC) layer transmission opportunities and physical (PHY) layer
channel conditions.
The present study provides analysis of Random Network Coding (RNC) and Systematic Network
Coding (SNC) decoding probabilities. Based on the analytical results, SNC is selected for
developing an adaptive network coding scheme designated as Frame-by-frame Adaptive
Systematic Network Coding (FASNC). According to network constraints per frame, FASNC
dynamically utilizes either Modified Systematic Network Coding (M-SNC) or Mixed Generation
Coding (MGC). An analytical model is developed for evaluating the mean decoding delay and
mean goodput of the proposed FASNC scheme. The results derived using this model agree with
those obtained from computer simulations.