Sensor & Actuator Networks
To achieve the goal of minimizing the buildings energy consumption and optimizing the energy use, the deployment of sensor nodes is crucial. These sensors could be used to measure the power consumed by the whole building or different individual appliances, including lighting.
The focal point for the building's energy consumption is the Smart Meter, which provides in near-to-real-time the amount of electricity being used in a three-phase installation. Figure 1 shows the installation of clamp smart meters in the IHU building. Upon installation, the smart meter begins communicating with collectors via its internal 433 MHz radio. The received data are involved in calculations to estimate the average power usage in different time intervals.
Figure 1. Smart meter installation in IHU building
To monitor the power consumption of individual electrical devices to which power is delivered, a large number of sensors are used. The project focuses on Low Rate Wireless Personal Area Networks (LR-WPANs), which are characterized by low-cost, low-power wireless devices with the ability of dynamic self-organization and self-configuration due to support of mesh connectivity. Figure 2 shows a wireless sensor network deployment based on IEEE 802.15.4. Each node in the network can transmit to any other node in the network that is within its radio transmission range allowing for multi-hop communication. Sensor data transmitted can be gathered, displayed and analyzed further at a central point, such as a pc.
Figure2. A typical zigbee network topology
The IHU platform will also accommodate sensors for developing building automation systems that manage the environment, fire and security, etc. These sensors will also rely on philosophy of the LR-WPANs. Figure 3 depicts a set of four zigbee sensors and a gateway that are being currently used for measuring temperature, humidity and luminance throughout the IHU building. The data that is measured at the nodes is transferred to a central processing server via the gateway.
Figure 3. A typical set of zigbee sensors and gateway
The project follows two research directions in the context of wireless sensor networks:
- Application of measurements in energy efficiency optimization: In this direction the correlation between measurements and energy efficiency is studied in terms of selecting the most lightweight-yet absolutely representative-building wide factors and related metrics that define the energy consumption. As an example, the energy consumption of the hosting the university’s data center servers is constantly monitored and correlated with the total computational load. The goal is to handle the computational load with the least possible energy.
- Optimize the performance of Low-rate Wireless Sensor Networks: Supporting real-time QoS in sensor networks has severe challenges due to characteristics of wireless networks such as energy limitation of sensors, low node reliability, and changes in the dynamic network topology. The planned project research in this field aims at the design of energy aware algorithms in Wireless Sensor Networks for saving energy both from the aspect of the communication protocol and packet routing, while providing QoS in terms of:
- Reliability
- Delay
- Scalability