الفهرس 
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Abstract
Wireless sensor networks (WSNs) are an emerging and promising area of interesting. WSNs consist of a large number of sensor nodes in a network can vary from hundreds to thousands and communicate wirelessly. Sensor Nodes in WSNs may be prone to faults due to energy consumption, hardware failure, communication link errors and malicious attacks or the harsh environments in which they are deployed. Self-healing mechanism in WSNs is an issue attaining a great arising attention nowadays. Self-healing mechanisms include fault detection and fault healing. Self-healing, in the majority of WSN environments, is performed centrally at cluster level. In this thesis, we proposed a Distributed Self-healing Approach (DSHA) in which detection and healing phases were performed at both node and cluster levels. In this thesis, detection phaseinthe proposed approach (DSHA) was performed at the node level for detecting the sensor node status and checking its behavior. Each sensor node identifies its own status to be either ”healthy” or ”faulty”. If the node status is declared as faulty, then it will be recovered by its next or previous neighbor. While, at cluster head level, the head receives both the calculated mean and heartbeat message from each node that exist within cluster during estimated period (t). The healing phase detects and recovers hardware faults in the sensor nodes. For this purpose, we addressed two distinct areas in this phase, namely fault diagnosis and fault recovery. The fault diagnosis was performed at two levels, they are node level and cluster head level.