Master Thesis - 2014

In recent years, the number of applications of wireless sensor networks (WSNs) has been increasing. In a WSN, one of the most important challenges is extending network lifetime since it is difficult to replace sensor nodes or recharge their batteries. In general, nodes around a sink tend to die earlier than the other nodes since such nodes have to forward more packets than the others. To overcome this problem, many load-balancing methods were proposed. By the way, overlapped multiple WSNs have been constructed within the same geographic area. In this situation, overlapped WSNs are expected to extend their lifetime by cooperative packet forwarding. Although some researchers have studied about cooperation in multiple WSNs, most of them do not consider the heterogeneity in characteristics of each WSNs. In a heterogeneous environment, the lifetime improvement with cooperation may not be fair. In this paper, we propose a fair cooperative routing method for heterogeneous overlapped WSNs. We introduce a shared node that has mul- tichannel communication capability as an interface node between different WSNs using different channel. When a shared node receives a data packet, it is able to forward the packet from a node via another WSN to the corresponding sink. A shared node selects a route to achieve longer lifetime and keep the fairness in multiple WSNs. Finally, we show the effectiveness of the proposed method by simulation experiments.