Fault-Tolerance Based On Network Coding In Wireless Body Area Networks

Wireless body area networks (WBANs) is an emerging and promising technology which will have a huge impact on all aspects of our lives in the future. For example, the health monitoring system based on wireless body area networks, which not only releases long-stay patients from the hospital, but also can reduce the cost of medical labor and infrastructure effectively. Whereas, in the WBANs, there are many problems such as the sensors with high mobility, energy limited and low transmission power, which result in a greater impact on signals transmission by environment, and it can easily cause packet error or packet loss. Thus, there is a strong need for fault-tolerance in the WBANs. To address the problem, we propose a WBANs error correction mechanism based on network coding. The main work and innovation of this paper can be summarized as follows:(1) The wireless body area networks can not only monitor the physiological signals of the human body, but also detect body posture. In the wireless body area network for posture detection, in order to detect the real-time human posture accurately, fault-tolerance of network need to be improved. Network coding can be used as a very efficient error recovery mechanism that greatly improves wireless body area networks reliability at very low computational and hardware cost. In a wireless body area network for posture detection, the accelerometer is responsible for collecting data. Firstly this paper propose that data is coded in the source node based on the characteristics, and gives data transmission and coding strategy. Simulation results that error recovery capability of the network coding at source node increase about 83% than the way that simply send the original packet twice, and it decode more quickly. Secondly, the paper propose error recovery mechanism of coding at relay node and shows the data transmission strategy and coding scheme. Simulation results that error recovery capability of the network coding at relay node increase about 83% than the way that simply send the original packet twice and 3% than the way that is proposed by Marinkovic. And when failure occurs in a single relay, the network using relay node coding still improve error recovery capabilities about 51%.(2) It is found that the majority of the existing error recovery mechanisms in WBSNs can’t support all requirements of the quality of service. Furthermore, investigations have been carried out in this paper to show that the network coding’s work fails to support adaptiveness to the channel conditions, and adaptiveness to the users’or applications’requirements, which are very important in critical medical applications,such as heart attack detection. Hence, to support these quality of service requirements, a network coding-based error recovery mechanism integrated with a priority differentiation scheme for WBSNs has been proposed in this work. This NC-based error recovery mechanism prioritize the data based on the real-time requirement and relay node encoding according to the data priority to adapt to the needs of channel and user’s quality of service. Simulation results show that the proposed encoding scheme ensure the higher priority packet loss rate below 1% when the system surfer from packet error rate of 42%. Overall error recovery capability of the network is by 51% over the previous coding scheme, and the proposed scheme effectively reduces the data retransmission, and energy consumption.