WSN Lifetime Optimization through Controlled Sink Mobility and Packet Bufferization

Maximizing the lifetime of energy constrained wireless sensor networks is a very challenging issue. It has been demonstrated that the use of a mobile sink can significantly increase the network lifetime by balancing the load among nodes. However, in existing solutions, nodes either send their data through multihop towards the sink or store the data until the sink comes at the node’s vicinity, which usually requires an infinite buffer capacity. In this paper, we propose a new approach in which nodes send their data through multihop towards the sink, but they have the possibility to bufferize data while waiting the sink coming closer (not necessarily at node’s radio range), which exempts more sensors from relaying these data. This strategy allows to save energy, while ensuring there is no data loss due to buffer overflow. We modelize the problem of optimizing WSN lifetime with limited buffer capacity and controlled mobile sink using a Linear Program (LP). For arbitrary topologies, our LP determines the sink sojourn times at each possible locations, the data transfer rates between nodes and the bufferized packets quantities. Compared to previous models, our solution achieves better lifetime and enables to generate and transmit more data to the mobile sink. We show that this lifespan prolongation does not results in an increased energy consumption at nodes level. Finally, the numerical results give useful indications for network dimensioning in terms of buffer capacity and link capacity.