Coding for wireless ad-hoc and sensor networks: unequal error protection and efficient data broadcasting

Efficient broadcasting;Wireless sensor networks;Unequal error protection;Multicast;Density evolution;Data dissemination;Rateless codes;Low-density parity-check codes;Modern error-control coding;Wireless ad-hoc networks;LT codes;Raptor codes

Rahnavard, Nazanin ; Electrical and Computer Engineering

University:Georgia Institute of Technology

Department:Electrical and Computer Engineering

关键词: Efficient broadcasting;    Wireless sensor networks;    Unequal error protection;    Multicast;    Density evolution;    Data dissemination;    Rateless codes;    Low-density parity-check codes;    Modern error-control coding;    Wireless ad-hoc networks;    LT codes;    Raptor codes;   

Others  :  https://smartech.gatech.edu/bitstream/1853/26673/1/rahnavard_nazanin_200712_phd.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

This thesis investigates both theoretical and practical aspects ofthe design and analysis of modern error-control coding schemes,namely low-density parity-check (LDPC) codes and rateless codes forunequal error protection (UEP). It also studies the application ofmodern error-control codes in efficient data dissemination inwireless ad-hoc and sensor networks.Two methodologies for the design and analysis of UEP-LDPC codes areproposed. For these proposed ensembles, density evolution formulasover the binary erasure channel are derived and used to optimize thedegree distribution of the codes. Furthermore, for the first time,rateless codes that can provide UEP are developed. In addition toproviding UEP, the proposed codes can be used in applications forwhich unequal recovery time is desirable, i.e., when more importantparts of data are required to be recovered faster than lessimportant parts. Asymptotic behavior of the UEP-rateless codes underthe iterative decoding is investigated. In addition, the performanceof the proposed codes is examined under the maximum-likelihooddecoding, when the codes have short to moderate lengths. Resultsshow that UEP-rateless codes are able to provide very low errorrates for more important bits with only a subtle loss in theperformance of less important bits. Moreover, it is shown that givena target bit error rate, different parts of the information symbolscan be decoded after receiving different numbers of encoded symbols.This implies that information can be recovered in a progressivemanner, which is of interest in many practical applications such asmedia-on-demand systems.This work also explores fundamental research problems related toapplying error-control coding such as rateless coding to the problemof reliable and energy-efficient broadcasting in multihop wirelessad-hoc sensor networks. The proposed research touches on the fourvery large fields of wireless networking, coding theory, graphtheory, and percolation theory. Based on the level of informationthat each node has about the network topology, several reliable andenergy-efficient schemes are proposed, all of which are distributedand have low complexity of implementation. The first protocol doesnot require any information about the network topology. Anotherprotocol, which is more energy efficient, assumes each node haslocal information about the network topology. In addition, this workproposes a distributed scheme for finding low-cost broadcast treesin wireless networks. This scheme takes into account variousparameters such as distances between nodes and link losses. Thisprotocol is then extended to find low-cost multicast trees. Severalschemes are extensively simulated and are compared.