Intra-City Road Network Modelling And Evaluation In Delay-Tolerant Networks

Delay-Tolerant Network is a new-style network model emerging in recent years, which is mainly used for data transmission in frequently-interrupted network. In the special environment such as outer space, remote mountain areas and enemy cities, etc., the connection between network nodes can not be maintained because of the special conditions. Therefore, the delay tolerant technology can be employed to satisfy the application requirement of military communications, environment monitor and remote sensing, etc. In DTN, the network topology is changed frequently due to nodes mobility. The mobility model is an important factor that affects the time-varying characteristics of the network topology and routing performance, further more, the behaviors of nodes in city environment are constrained by the road network. Therefore, it has a very significant meaning to construct the way network models and analyze the impacts of way network to the network topology and routing performance.In this thesis, we have studies the characteristics, architecture and related technologies of DTN, compared DTN with traditional network on network characteristics and routing methods and classified the mobility model based on their properties.Then we get the real city way data of the world of the Internet, extract the way data and analyze the statistics of the way networks performance. Based on the current way network model, a new probability parameters model–PGRM(Probability Grid Road network Model,PGRM) is proposed. The processing chart of this model is illustrated and the main properties of way network in this model are analyzed. Experimental results show that this model is more suitable for the real city environment modeling.In order to study the way network constrains to the node mobility and network topology characteristics, The ONE simulation framework is used to prove the model validity. The simulation is based on the Random Way-Point (RWP) and PGRM model, and the network topology performance of the two models is compared. Then based on the way parameters and probability parameters, the relationship of the road network model parameters and network topology are analyzed.Through two DTN routing protocols, the model mobility performance is evaluated and the routing performance is compared under the RWP and PGRM models. Then based on the way parameters and probability parameters in PGRM, the impact of road network model parameters change on routing performance is analyzedExperience results show that, way number, map nodes number, the dense or sparse degree of the ways, and the grid acreage have significant impact on the network topology and routing performance.In summary, our research has an academic and practical value for the DTN node mobility model in city environment, and it is a beneficial work for advancing the DTN routing protocol performance.