Research On Multi-Path Routing Of Wireless Sensor Networks For Undergound Mine

It is known that the environment of underground coal mine is very sophisticated and changeable, which leads to increasingly insecure and sometimes fatal accidents in the course of mine exploitation. At present, the situation of safe production of coal mine is very serious in our country, and mining accidents occur frequently in recent years which cause very enormous loss of life and property. The existing coal mine security monitoring system is urgent to be improved with all sorts of insufficiencies which can't meet the increasingly stringent demand of safety.Tracking and positioning technologies is one of the primary methods to improve coal mine safety. In the event of a mining accident, a rescue plan can be drawn up timely and accurately through locating and tracking the trapped workers, so that the casualties will be kept to a bare minimum. How to improve the reliability of communication system of tracking and rescuing for underground mine (CSTR) by the application of multi-path routing is the main research point of this thesis. The main contributions of this thesis are listed as follows:1. The existing methods of reliable data transmission and routing protocols have been analyzed in order to give the advantages, disadvantages and performance of them, which is useful to design a better routing strategy. To providing a theoretical basis for algorithm design, in this thesis the following two studies were made:on one hand, the reliability theory was utilized to analyze two kinds of disjoint and non-disjoint multipath routing methods. The results of the analysis have shown that more routing redundancies could be provided by the non-disjoint multipath routing under the state of unstable wireless network link, which made the method more reliable. In addition, the reliability of non-disjoint multipath routing could be improved more with less unstable of the wireless network link. On the other hand, the value of the number of paths and hops was optimized through theoretical calculation and simulation.2. On the basis of AODV algorithm, a multi-path routing algorithm based on minimum hop was proposed (MHBMP) in this thesis. Firstly, in order to avoid the information explosion caused by flooding, the directions of broadcasting RREQ were in MHBMP controlled through establishing the minimum hops from the sink. Secondly, as a protocol of energy efficient and load balanced, the delay of a node was determined by its current energy level and load, so the nodes with more residual energy and fewer loads could be selected quickly, and energy consumption in the network could be reasonable, and node loads could be more balanced. These result in that the data flow could not be clogged in some section. Thirdly, in the process of path selection, crucial energy of every nodes was calculated in order to construct an energy-balanced network, and then according to crucial energy ratio energy-balanced among the nodes was achieved. In addition, local repair mechanism was proposed,which attempted to enhance the reliability of the path in this thesis.3. In this thesis, the proposed protocol was described in detail and a simulation experiment was made on the NS2 platform. From the view of transmission reliability and energy effectiveness and through comparing and analyzing other methods in packet delivery, delay, routing overhead, node lifetime, algorithm mentioned in this thesis proved to be more effective and reliable.