Software update recovery for Wireless Sensor Networks

Updating software over the network is important for Wireless Sensor Networks in support of scale, remote deployment, feature upgrades, and fixes. The risk of a fault in the updated code causing system failure is a serious problem. In this paper, we identify a single, critical, symptom loss-of-control, that complements exception-based schemes, and supports failsafe recovery from faults in software updates. We present a new software update recovery mechanism that uses loss-of-control to provide high-reliability, low energy, software updates, including a comparison of optimised-flooding against spanning-tree for determining loss-of-control in a multi-path environment. The solution presented supports a trial phase (with lower latency), and an operational phase (with lower energy). The energy/latency tradeoff of this is shown, and the high-reliability of this update recovery is demonstrated by analysis and simulation. The results presented control the risk in existing WSN software update mechanisms.