TWIST was chosen as ground truth architecture for EDI Testbed, but with modifications:
- Ethernet switches were replaced with PoE switches. PoE switch supports data transfers and power delivery. There are two PoE IEEE standarts: 802.3af, max power rating is 15.4W, second – 802.3at, max power rating 25.5W. This modification allows us to decrease set-up costs and place micro-servers more freely in desired places, but we can’t exceed power limitations, thus power efficient micro servers must be used.
- To overcome traffic overloading between central and micro servers, global commands where introduced:
- Data acquisition – all acquired sensor data from sensor node are stored on micro-server. Central server requests stored data from micro-server.
- Data (pre)processing – basic manipulations with acquired sensor data are performed on microserver, thus reduced overall computational power on central server, thus reduced transferred data amount ((pre)processed data amount are lesser than raw data amount).
- Additional module, EDI Testbed adapter (described in subsection TestBed adapter), is introduced. It is placed between micro-server and sensor node. Our developed module allows users accurately evaluate designed WSN performance. It provides with additional information: power consumption measurement, battery discharging emulation, real-world sensor data emulation, analog/digital signal debugging.