Research On The Key Technologies Based On Broadcasting In Wireless Sensor Networks

Recently,wireless sensor networks have been widely used.As the main transmission modes in wireless sensor networks,broadcasting has also been studied by many domestic and foreign scholars.Different from traditional networks,WSNs are often constrained by resources,including short communication distance,limited node energy,low transmission bandwidth,and limited processing and storage capacity of nodes.At the same time,due to poor environment conditions where the network deployed,the links between nodes are often unstable.These issues should be taken into account when designing algorithms and protocols for wireless sensor networks.The traditional broadcasting could easily lead to heavy packet redundancy,channel conflicts and contention,that is,the issue of broadcast flooding.The trickle algorithm,a broadcast scheduling algorithm developed for wireless sensor networks,could effectively reduce the forwarding of redundant messega.IPV6 Routing Protocol for Low Power and Lossy Networks and Multicast Protocol for Low Power and Lossy networks have employed Trickle algorithm as a basic mechanism for message dissemination.By adopting a “polite gossip”policy,trickle algorithm could quickly propagate update message and prevent broadcast flooding.We present an analytical model of Trickle algorithm in lossy networks,which takes the loss rate of the network into consideration.Since the packet loss degrades the network performance by increasing traffic load,we propose a terminable Trickle algorithm for lossy networks.Once a node could not hear a consistent message from a new neighbor or an inconsistent message for continuous some intervals,this node will stop persistently broadcasting.Simulation results validate that the proposed algorithm could update the network over 99% even if the loss rate comes to 70%.The bandwidth is very low in wireless sensor networks,could cause the performance bottlenecks when the sink node collects and delivers the data.Coded caching,which takes advantage of the ”one-to-all” transmission of broadcast,can reduce the consumption of network bandwidth.Compared to conventional uncoded caching schemes,in addition to the local caching gain,cached caching scheme is able to achieve global caching gain.Taking into account the delay sensitivity of some applications,and in order to maximize the global cache gain,we need to design the rules for merging requests.We introduce three kinds of rules for merging request,namely the first-fit rule,the perfect-fit rule and the ?-fit threshold rule.Using the first matching rule,we implement the video living system based on coded caching.When designing this system,we consider some issues,like processing video file,queue design in server,and network packet loss.Finally,we set up the test system including two clients and adopt a random strategy in the placement phase.From the result,our system can bring significant gain compared with the traditional file transfer system,even if there exits packet loss in the network,the coding gain is nearly 1.3,which could approximately reduce the server bandwidth by 25%.