Investigation On Erasure Correction And ARQ Schemes In Wireless Sensor Networks

Wireless sensor networks is an intelligent network system that integrates information collection,processing and transmission functions,it has the characteristics of high flexibility,low cost,and high self-organization,it has a very wide application prospect in the fields of military,environmental monitoring,smart cities,agriculture,forestry,fishery,animal husbandry and health care.Because wireless sensor networks nodes have limited resources and are often deployed in some harsh environments,data transmission will be affected by unfavorable factors such as multipath fading,node failure,link interruption,path loss and shadow effects,which can easily cause data packet loss,so data transmission is often not guaranteed.This thesis mainly studies the problem of data packet loss during wireless sensor networks transmission,and designs and implements a low-complexity reliable data transmission scheme based on RS codes packet recovery and a reliable data transmission scheme based on ARQ retransmission.Specific work includes:In the reliable data transmission scheme based on RS codes packet recovery,The sensor node first caches a certain number of information data packets in the data packet group,and then encodes the data symbols in the same position of the data packet by RS codes,and places the generated redundancy check symbol behind the corresponding position of the data packet to obtain a set of redundant data packets.and then each packet of data is then subjected to turbo encoding and interleaving for packet transmission.The sink node receives the data packets for packet transmission based on four antennas,and completes the processes including frame header recovery,data merge,de-interleaving,turbo decoding framing,and RS decoding in sequence.Test the solution in land and marine environments,and use Packet Loss Rate(PLR)as a performance metric.Test results show that the reliable data transmission scheme based on RS codes packet loss recovery can effectively and accurately recover lost data packets under the condition of low packet loss rate,ensure the integrity of information transmission,and improve the reliability of unidirectional channel data transmission.In the reliable data transmission scheme based on ARQ retransmission,a method of ARQ retransmission and collaborative communication diversity based on Ymodem communication protocol is designed and implemented.In order to meet the requirements of embedded systems due to storage space limitations and different test functions,the sensor nodes remotely update the program files through the ARQ retransmission method based on the Ymodem communication protocol.At the same time,in order to ensure the reliable upload of sensor data,this method improves the reliability of multi-path transmission through cooperative diversity technology.The data packet structure is further designed,implemented in hardware and software.Finally,the actual comparison test with the stop-and-wait ARQ scheme,the results show that the reliable data transmission scheme based on ARQ retransmission has fewer retransmissions and higher reliability than the stop-and-wait ARQ scheme.