Distributed Joint Network-Channel Coding in Multi-Hop Wireless Networks

Abstract

This thesis focuses on the design of distributed joint network-channel coding in multi-hop wireless networks. There are two main research focuses in this thesis, the first one is applying the low-density generator matrix (LDGM) codes to the design of joint network-channel coding, and the second one is designing joint network-channel coding schemes based on fountain codes. To begin with, I apply the LDGM codes to the design of joint network-channel coding. A multiple transmission session model with network code division multiplexing (NCDM) scheme is proposed to remove the inter-session interference at each destination. New code design criteria for the construction of the generator matrix are proposed. Another focus of this thesis is the design of joint network-channel coding using fountain codes. I first propose a distributed network coding (DNC) scheme based on the Raptor codes for wireless sensor networks (WSNs), where a group of sensor nodes, acting as source nodes, communicates with a single sink through other sensor nodes, serving as relay nodes, in a multi-hop fashion. To satisfy the various performance requirements of different source nodes, I propose an unequal error protection (UEP) DNC scheme based on fountain codes to provide arbitrary error protection (i.e., infinite protection levels) to all the source nodes in wireless relay networks (WRNs). Then I investigate the effect from different parameters of the degree distributions. A degree distribution design criteria are proposed for the DNC scheme based on fountain codes over Rayleigh fading channels. In addition to minimizing the overall recovery time among all protection groups, I develop an adaptive UEP DNC scheme to realize adaptive UEP in WRNs. The transmitted data from the source nodes in different protection groups can be recovered successfully under their performance requirements in a shorter time by using the adaptive UEP DNC scheme.