Applications Of WSN For Water Quality Online Monitoring

With the population expansion and rapid economic growth, environmental pollution has become increasingly serious, especially in recent years, water pollution, has become an issue constraining China's economic development and improvements of people's living standards. Wireless sensor networks with network flexibility, low cost, no need for infrastructure, has become a research hotspot in the field of environmental monitoring.The thesis employed wireless sensor network in water quality monitoring systems, studied and developed a water quality monitoring network, which is multi-hop, self-organizing capacity and possesses the ability of both short-range wireless communication and web-enabled access.The RSSI channel attenuation model for the wireless sensor networks has been studied and used in ACA routing protocols. RSSI link cost based ACA routing protocol is proposed, releasing the blindness in the link evaluation process of the original protocol. Compared with the traditional ACA protocol, wireless network based on RSSI-ACA routing protocol has a low transmission delay and the number of multi-hop. The success rates in data transmission and energy efficiency have also been enhanced, improving the network system communication quality and prolonging the survival time of the network.The RSSI-ACA routing protocols are implemented in the network layer and application support sub-layer of TinyOS operating system. IEEE802.15.4/ZigBee standards are compatible, supporting carrier sense collision avoidance mechanism and possessing the functions of message loop suppression and forward message buffering.The modularization and interfaces encapsulation technology shields multi-hop and path optimization details, reducing the difficulty and coupling of the RSSI-ACA routing protocols, providing best (best-effort) data transmission services for the TinyOS application layer.In the application layer of the TinyOS operating system, the functions of water quality monitoring nodes and aggregation nodes are achieved. Application communicates to the PLC and GPRS DTU through the serial port module in the data flow level; by calling the RSSI-ACA protocol, the function of water quality monitoring data aggregation is implemented. A complete solution is accomplished for the for the water quality monitoring system in data collection, transmission, storage and other key aspects. A heterogeneous water quality monitoring network possessing the ability of both short-range wireless communication and web-enabled access is established.