Cooperative transmission range doubling with IEEE 802.15.4

In battery-driven multi-hop wireless sensor networks, the most highly burdened relay nodes, or bottleneck nodes, will die first. These deaths eventually partition the network and trap valuable battery energy in the network. In a multi-hop wireless sensor network that must harvest energy from weak energy sources, the nodes that are one hop away from the Sink must sometimes shut down to harvest, so they limit the access that the rest of the network has to the Sink. One way to lengthen the time-to-partition or increase access to the Sink is to exploit some of the would-be-trapped energy to do cooperative transmission (CT) range extension to hop over the bottleneck node and communicate directly with the next-hop node (e.g., the Sink). To do this, approximate range doubling is necessary. In this paper, we investigate the potential for range doubling over Rayleigh faded channels of four CT schemes that are compatible with the IEEE 802.15.4 standard. We consider the effects of path loss disparities and how many cooperators are necessary for each CT scheme.