Optimal single-session flow routing for wireless sensor networks

Wireless sensor networks are becoming increasingly important in recent years due to their ability to detect and convey real-time in-situ scenes for many civil and military applications. A major technical challenge for a wireless sensor network lies in the energy constraint at each node, which poses a fundamental limit on the network lifetime. We consider two-tiered wireless sensor networks and address the network lifetime problem for upper-tier aggregation and forwarding nodes (AFNs). Prior efforts have formulated the network lifetime problem into a linear programming (LP) that results in a multi-session flow routing solution. Under multi-session flow routing, each AFN must be equipped with multiple transmitter to reach various destinations at the same time, which poses a scalability problem in practice. This paper shows that, by exploiting dynamic power control at an AFN's transmitter, a multi-session flow routing solution can be converted into an equivalent single-session flow routing solution (requiring only a single transmitter at each AFN). Consequently, it shows that it is possible to design a single-session flow routing solution that has the same optimal network lifetime as a multi-session flow routing solution.