Research On A Parking Guidance And Information System Based On Wireless Magnetic Node

Parking problems have become ubiquitous social problem in every major city of the world. So a lot of research and development have been launched both in academic and industry, with the purpose of finding a better and more intelligent parking management solution. With the rapid development of wireless sensor network (WSN) technology, coupled with wireless applications have many advantages for smart parking, the parking guidance and information system (PGIS) based on WSN has become a hot research direction that is used for solving city parking problems.At present, researches on PGIS using WSN mostly focus on the layered implementation of system architecture, improving the throughput of the system and reducing the packet loss rate, etc. But there are few studies involved in wireless communication protocol of underlying data collection network, system energy consumption and network reliability. Aiming at these problems, this paper, which combines with the key technologies of PGIS, WSN technology and mature wireless magnetic sensing technology, makes an in-depth study on communication protocol of the data collection network in indoor parking lot and further designs and realizes a prototype of the parking guidance and information system based on wireless magnetic nodes.The main contribution of this paper can be summarized as follows:(1) We propose a data collection protocol named P-CTP (Parking Collection Tree Protocol) for indoor parking lot application. To meet the low power and high reliability requirements in parking scenarios, P-CTP protocol, which is an improved Collection Tree Protocol (CTP), is able to ensure the reliability of wireless data transmission, minimize energy consumption of wireless communication in WSN and maximize the lifetime of system. This paper not only introduces the basic principle of P-CTP in detail, but also designs and implements all modules of the protocol, including link estimator, routing engine and forwarding engine. Meanwhile, we use nesC language to realize P-CTP by programming and the procedure is based on TinyOS operating system and the software architecture of CTP. Through multiple sets of contrast experiment, we evaluate the performance and effectiveness of the P-CTP. The experimental results show that a number of performance indicators of the P-CTP, such as energy consumption, packet loss rate, network latency, etc., can satisfy the needs of parking lot application.(2) This paper designs and implements a prototype of the parking guidance and information system based on wireless magnetic nodes for helping users quickly find a suitable parking space. The prototype system supports parking spaces monitoring, remote management of a parking lot, parking guidance services and some other functions. In this system, wireless magnetic nodes are used to monitor states of parking spaces and the monitored data is transmitted by an integration of WSN and wired local area network. In general, this prototype system consists of four kinds of nodes, namely monitoring nodes, relay nodes, sink nodes and guide nodes, and an information management control center. Each kind of node plays a different role in the system and different types of nodes or control center communicate with each other by direct or indirect ways. This paper carries out two aspects of prototype system experiments to evaluate the system performance. On the one hand, through the parking condition monitoring experiment, we evaluate and analysis the magnetic field strength performance of wireless magnetic nodes and the effectiveness of the parking space monitoring program. On the other hand, through the contrast experiments of prototype system, we evaluate the performance of the system, including packet loss rate and network time delay, and compare it with the PMS prototype system. The results show that the performance of our prototype system is superior to that of the PMS System.