Application Research Of The Data Distribution Technology In LLN Based On Fountain Codes

Low-Power and Lossy Networks (LLN) is a kind of the smart objectsnetworks.It is consisted by devices whose memory,energy and processing abilityare limited.And the devices are interconnected by lossy links.LLN lies at the endof the Internet of Things (IOT).Its object is to link the physical world and thecommunication networks.The research and experiment of LLN have an importantsignificance for the future development of the communication networktechnology.At present,the main technical support of LLN is IPv6Routing Protocol forLow Power and Lossy Networks (RPL) which is particular designed for LLN.Thisrouting protocol is still be designing. RPL uses a series of new ICMPv6messagesto construst the topology and runs certain routing rules to create routing.6LoWPAN select RPL as its routing protocol.RPL is a distance vectorprotocol. The physical layer and link layer of6LoWPAN use IEEE802.15.4technology specification.but the payload length of IEEE802.15.4is less than thatof Ipv6in network layer.6LoWPAN add an adaptation layer using compressingand slice operations to match link layer and network layer.So6LoWPAN is alsoknown as a lightweight IPv6protocol.Fountain codes is a class of forward error correction code and can be appliedto many kinds of channels.In the process of data transmission, it realizes nofeedback expectations.It also has small complexity of coding and decoding,highsuccess rate of encoding.This paper uses LT codes,BP decoding method and robustSoliton degree distribution to handle the data.Modeling of LLN network is done on the NS3networksimulation platform:set up the network simulation scene,construct eachsimulation module and then realize data distribution function.By adding a fountaincodes encoding and deconding module,packets can be handled in the transmitterand receiver.It is proved that fountain codes make great improvement andoptimization on performances of LLN by comparing the impact of fountain codes on the packet loss rate,throughout and average delayin different simulationscenaries.At the same time,this paper also analyzes the performanceof fountaincodes in the specificenvironment of LLN networks to choose the best combinationofthe encoding overhead and decoding failure ratethat the network can bear.