Low-Cost Wireless Sensor Network for Small Area in a Building

Multisensor system can be found in many areas. In a modern laboratory, houses or other buildings, multiple sensors are used to monitor different quantities. Data from each sensor are sent to the data server for further processing. Data communication between the sensor and the server using cabling system are disorganized and inconvenient. The solution for that problem is by using wireless communication. For such approach, the energy consumption and radiation power of the system are important factors. This paper presents a model of wireless sensor network for multipoint measurement in a building. A multipoint monitoring system for temperature and humidity was implemented using distributed sensor system connected with IEEE 802.15.4 wireless communication. The system was implemented using Microchip MiWi wireless transceiver module, low power microcontroller, and sensors. At the server side, a network controller was built using a microcontroller and MiWi transceiver. The microcontroller and data server were connected using HID protocol. The HID protocol was chosen because the data rate from the sensor node to the server is low. The network configuration was a star configuration with a direct link between the sensor node and network controller. Packet length, the maximum distance between transceiver and power consumption, was measured. The result shows that at the power of -30dBm, the communication can be established well within 15 meters. At the minimum power, the sensor node can operate up to 5 days using the 3.3V, 2500mAh lithium battery.