Time slot allocation in WSNs for differentiated smart grid traffic

Wireless Sensor Networks (WSNs) are emerging as promising tools to aid in monitoring the smart grid. WSNs can be easily deployed in a wide number of smart grid assets such as substations, overhead power lines and power generation sites. They offer ubiquity and flexibility at a low-cost. However it may be difficult to offer the Quality of Service (QoS) demanded by the smart grid applications with WSNs since sensor nodes share the same wireless communication medium. To overcome this challenge QoS-aware medium access is essential. In this paper, we propose the QoS-aware GTS Allocation (QGA) scheme which aims to reduce the end-to-end delay of delay-critical data while routing delay-tolerant data using unutilized resources. QGA is implemented for a multi-hop, mesh network topology which is the most flexible WSN deployment. In QGA intermediate level sensor nodes run an optimization model in order to perform optimum time slot allocation to minimize the delay of critical data. Meanwhile, delay-tolerant data is buffered until the delay-critical traffic passes through this relaying node. Smart grid monitoring application determined whether data is delay-critical or not based on the alarm values. For instance, a transformer overloading measurement is treated as delay-critical while an ambient measurement corresponding to room temperature is treated as delay-tolerant. We show that QGA significantly reduces the end-to-end delay of high priority traffic.