Activity scheduling based on cross-layer information in Bluetooth sensor networks

In this paper, we consider a Bluetooth scatternet acting as a sensor network, in which we implement an energy efficient congestion- and event-based reliability control scheme. Event reliability is defined as the number of data packets with sensing information collected by the sink per second. We propose two algorithms for congestion and event reliability control. The first algorithm maintains the required (fixed) event reliability at the sink using minimal slave activity. It uses pre-calculated activity values obtained from the analytical and simulation models of the network. The second algorithm keeps the whole network within the acceptable range of packet losses using the minimal slave activity. In this case source piconets use the information measured at the sink in order to regulate the activity of the slaves. The reliability obtained at the sink, bridge buffer loss rates, and end-to-end delays are analyzed for power controlled piconets within the sensor scatternet. The proposed algorithms significantly reduce congestion and source-to-sink delays, while minimizing packet losses due to finite buffers in the bridge nodes.