Fault-Tolerance Mechanisms For Body Sensor Networks

As an important part of the Internet of Things, Body Sensor Network (BSN) is a kind of interdisciplinary super short wireless network that is utilized to improve people's healthcare by pervasive computing and intelligent information processing. A high degree of security and reliability for critical data transmission is required in BSN. In this thesis a fault-tolerance mechanism for BSN is presented.BSN may fail when intrusions occur because of the characteristics of energy-sensitiveness and resource-limitedness, and is usually vulnerable to channel impairments due to body fading effect and RF interference. Moreover, inter-user interference will be introduced by the simultaneous communication of BSN congregating in the same area. All of them may potentially cause unreliable data transmission. In terms of the characteristic and reliability requirement of BSN systems, the fault-tolerance scheme proposed in this thesis includes intrusion tolerance, adaptive fault-tolerant communication and decentralized inter-user interference suppression. In the intrusion tolerant scheme, intrusions are dynamically detected according to the collected intrusion-related information. By utilizing replicas classification and two-step threshold-based intrusion detection, it provides an adaptive intrusion tolerant strategy with passive replication. The adaptive fault-tolerant communication adopts a bandwidth reservation strategy to provide reliable data transmission when channel impairments occur. In order to fulfill the reliability requirements of critical sensors, fault-tolerant priority and queue are employed to adaptively adjust the channel bandwidth allocation. In decentralized inter-user interference suppression algorithm, each BSN measures the interference from other BSNs and then adaptively selects the suitable channel and transmission power. Through non-cooperative game theory and no regret learning algorithm, it provides an adaptive inter-user interference suppression strategy.The correctness and effectiveness of the scheme is theoretically proved. Simulation results show that it can effectively tolerate intrusions with low power consumption and high adaptability, alleviate the effect of channel impairments yielding lower packet loss rate and latency for critical sensors at runtime, and reduce the effect of inter-user interference.