Opportunistic File Delivery by Network Coding in Vehicular Networks

• Main Authors: Shih-hao Lin, 林士豪
• Other Authors: Tai-Lin Chin
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/40554216572206485828

碩士 === 國立臺灣科技大學 === 資訊工程系 === 98 === Mobility of vehicles in a vehicular ad-hoc network frequently results in network partitioning and route disconnection for packet forwarding. Conventional mechanisms of route discovery and maintenance are usually infeasible in vehicular ad-hoc networks. As a result, successfully transferring a file in a vehicular ad-hoc network is much challengeable than doing that in traditional mobile ad-hoc networks. In this thesis, an opportunistic forwarding mechanism incorporating with random linearly network coding is proposed to carry out file forwarding in a vehicular ad-hoc network. The file is divided into a series of blocks, namely raw blocks. Coded blocks generated by the raw blocks with different linear combination coefficients are forwarded to the receiver. Traditionally, file forwarding has to successfully deliver all the raw blocks to the receiver side and, thus, wastes longer time and delivery ratio may be lower. With network coding, the receiver just collects any coded blocks met on its way and recovers the original file using coded blocks with linear independent coefficients. In particular, the number of the coded blocks used to recover the file is the same as the raw blocks used by the traditional forwarding method. Since the receiver does not need to wait every single raw block, the end to end delay of file forwarding is reduced and the delivery ratio is improved. In addition, a store and forward approach is developed to achieve effective block forwarding in sparse vehicular networks. Simulation results show that our forwarding mechanism effectively improves data delivery ratio and end to end delay in a vehicular ad-hoc network.