Theory And Application Research On Greedy Perimeter Stateless Routing Algorithm Based On Geographical Locations

As an important part of the subject,"Continuous on-line detection principle research on generating and melting process of ice layer and mechanical stress based on physical characteristics among air, water, ice"(No.51279122) supported by National Natural Science Foundation of China, this dissertation aims at taking the concrete ice condition measurement environment into consideration and having in-depth study on theory and application of routing algorithm based on geographical locations for wireless sensor network.The micro-electro-mechanical systems (MEMS) led to the development of tiny sensor nodes with logic functions, monitoring and communication capabilities. The limited processing and communication capabilities of sensor nodes, as well as the restricted energy resources available for sensor nodes, making the routing problem has increasingly become a hot and difficult issue in wireless sensor network consist of these small size sensor nodes. Among plenty of existing routing protocols, Greedy Perimeter Stateless Routing (GPSR) protocol proposed by Brad Karp and H.T.Kung of Harvard University has been showing good performance over other protocols due to its higher packet delivery success rate and lower routing protocol overhead. However, the efficiency of GPSR protocol mainly comes from its greedy forwarding mode which takes full advantage of the wireless network communication link; The completeness of GPSR is primarily dependent on its perimeter forwarding mode which can be carried out when the greedy forwarding mode fails, thus avoiding the entire protocol being in invalid.These two features of the GPSR making it a model in wireless routing protocols based on the geographical locations.Meanwhile, the perimeter forwarding mode has also become the bottleneck of the protocol. This is a very worthy study and concern. At present, many domestic and foreign experts and scholars have launched a deepgoing research on this issue. In this paper, the process and principles of greedy and perimeter forwarding modes was analyzed in detail; the in-depth analysis to the flaws of the perimeter forwarding mode was conducted; many existing improvement strategies on this protocol proposed by researchers at home and abroad in recent years was summarized. Combined with specific application environment of ice condition measurement, an improved strategy on the perimeter forwarding mode of the protocol GPSR was proposed and achieved in this article. The simulation and evaluation results show that the improved protocol GPSRI performs better than the original protocol. The bottleneck problem caused by the face routing mode is solved. From the point of view of the reliability of wireless sensor network routing protocols, a series of technical problems including multi-path realization has been achieved in this GPSRI proposed in this paper. Specifically, the main content of this article contains the following three aspects:(1)Face routing mode with the right-hand rule ensures that data packets are capable of solving the problem of the "holes". When encounters frequently the "holes" in the routing process, the protocol could not solve it with low cost due to a large number of hops caused by a certain degree of arbitrariness of the protocol GPSR making decisions in the perimeter forwarding mode. In this paper, the detailed analysis on the process of sovling the "hole" problem was introduced and the fallback strategy to solve the face routing problem was proposed.(2)Greedy perimeter stateless routing protocol is likely to go very far in the wrong path. During the research process, make use of shortest or shorter path in data packet transmission to ensure the smallest or smaller end to end transmission delay on the basis of the fallback strategy and path optimization algorithm proposed in the improvement procedure of the perimeter forwarding mode in this article.(3)GG and RNG planar graph algorithms are adopted in GPSR.In order to avoid causing network partition in the topology, the cross edges in the topology need to be removed with the help of GG and RNG algorithms. However, the connectivity of the graph may be destroyed due to the special mode of obstacles among the sensor nodes. Thus, a face can not reach another neighboring forwarding face, leading to the problem of destination node being unreachable. Aiming to solve this problem, the node-disjoint multipath was achieved so as to improve the reliability of data delivery in wireless sensor networks.Considering the characteristics of ice disaster forecasting system which is a wireless sensor network built in the upper reaches of Yellow River, such as: restricted energy of the sensor nodes, frequently changing topology, etc, the coordination among the sensor nodes during the process of ice condition measurement without user intervention was implemented in GPSRI. Furthermore, any node failure or missing could not affect the sensoring functions for the entire wireless ice condition forecasting sensor network system.