Extended center description and neighbor-copy with improvent of wireless sensor networks

We aim to optimize the lifetime of wireless sensor networks, which consist of one data collector base station (BS) and numerous randomly scattered sensors with limited energy in this thesis. Network lifetime is measured as the time until the first sensor exhausts its battery. Moreover, we incorporate network security via balanced utilization of sensors and multiple copying against possible external attacks or breakdowns. The amount of data each sensor can receive from others is limited from above by some constant. However, if it would improve network lifetime then only one sensor is allowed to exceed the limit and become a central node. Due to its critical role in data flow, the central node is more likely to be exposed to external attacks or possible breakdowns. To this end, we propose a partial multicopy strategy where sensors transmitting data to the central node would copy that data and send it to the BS through node-disjoint paths. Consequently, we can avoid unnecessary data copying to some extend and use energy more efficiently. Transmitting extra data at the expense of extra energy would shorten the network lifetime. Hence there is a tradeoff between network lifetime and network security. We present the mixed-integer programming model of the problem and an optimization based heuristic algorithm developed especially for solving larger instances. We analyze the performance of these solution methods on a large testbed.