Self-* distributed query region covering in sensor networks

Wireless distributed sensor networks are used to monitor a multitude of environments for both civil and military applications. Sensors may be deployed to unreachable or inhospitable areas. Thus, they cannot be replaced easily. However, due to various factors, sensors\u27 internal memory, or the sensors themselves, can become corrupted. Hence, there is a need for more robust sensor networks. Sensors are most commonly densely deployed, but keeping all sensors continually active is not energy efficient. Our aim is to select the minimum number of sensors which can entirely cover a particular monitored area, while remaining strongly connected. This concept is called a Minimum Connected Cover of a query region in a sensor network. In this research, we have designed two fully distributed, robust, self-* solutions to the minimum connected cover of query regions that can cope with both transient faults and sensor crashes. We considered the most general case in which every sensor has a different sensing and communication radius. We have also designed extended versions of the algorithms that use multi-hop information to obtain better results utilizing small atomicity (i.e., each sensor reads only one of its neighbors\u27 variables at a time, instead of reading all neighbors\u27 variables). With this, we have proven self-* (self-configuration, self-stabilization, and self-healing) properties of our solutions, both analytically and experimentally. The simulation results show that our solutions provide better performance in terms of coverage than pre-existing self-stabilizing algorithms

The Smart Stone Network: Design and Protocols

The Smart Stone Protocol (SSP) has been developed to achieve rapid synchronization in a wireless sensor network, establish Time Division Multiple Access (TDMA)communication slots, and perform distributed sensing with global shared awareness. The SSP achieves a synchronization precision of 50μs among receivers. The sender is synchronized to the receivers using a novel scheme to identify the closest comparable times on the sender and receiver. The protocol is tightly related to events that occur in the mote hardware, and is designed to operate on resource constrained wireless sensor motes. Robust TDMA communication slots are set up based on the achieved synchronization, and an innovative algorithm is employed to maintain synchronization without sending any additional synchronization bytes. To test and validate the protocol, Smart Stones have been custom designed using commercial off-the-shelf (COTS) components, and the SSP has been successfully demonstrated on the Smart Stone Network performing an acoustic sensing application