Reliable Transmitting Mechanism with Network Coding in Wireless Sensor Networks

Abstract: Wireless sensor networks always have limited energy, and they are low cost, distributed and self-organized. They are always located in very special environment and improve people’s ability to obtain information. Energy efficient transmitting mechanism is very important for wireless sensor networks. Many researches have been developed about reliable transmitting; they mainly focus on retransmitting and redundant transmitting. With the development of network coding, the nodes can not only forward the packets but also process them with network coding, so it improve the reliability, but it also brings the problem of how to decide the number of redundant packets.This thesis surveys the research status of reliable transmitting in wireless sensor networks, and then also gives the detail of main retransmitting and redundant mechanism.In order to improve the reliability of transmitting, this thesis proposes a reliable transmitting mechanism based on control message, the sender selects two points whose reliability is the highest in its neighbors, when it cannot receive the ACK from one node, it can ask another node to send as the other node has receive the packet with a large probability. In such a way, the sender can reduce its number of retransmission. The simulation results show this mechanism can reduce the number of transmission comparing with RMRNC.In order to adjust to the distribution of sensor networks, this thesis then proposes a network coding transmitting mechanism considering redundant packets controlling. Every node calculates the number of packets it should send to decide the number of redundant packets. The simulation results show that the number of transmission it needs even less then the mechanism of retransmitting based on ACK when the channel error rate is high.
Key words: wireless senor networks; reliable transmitting; network coding;