Network Coding-Based Real-Time Retransmission Scheme in Wireless Sensor Networks

In wireless sensor networks (WSNs), wireless links are unreliable and sensor nodes may be in sleep mode. Thus, many applications which require reliable broadcast cannot work properly if they lost some packets. In order to make sure every sensor node in the network receives all packets completely and correctly, retransmission of lost packets is indispensable. Many retransmission methods with network coding have been proposed but they do not catch coding opportunity. In this paper, real-time retransmission algorithm based on network coding (NCRR) is proposed to make the average number of transmissions as less as possible. During the transmission of original packets, we detect whether a certain time slot is suitable for retransmitting a coded packet based on recovery ratio. We analyze the number of transmissions with traditional retransmission and with network coding. Compared with existing approaches, simulation results show that our algorithm can effectively reduce the average number of transmissions and improve the transmission efficiency.