[Show abstract][Hide abstract] ABSTRACT: Vehicular Ad Hoc Network (VANET) has recently attracted considerable attention. The design of routing protocol for VANET is a challenge given rapid topology changes and frequent network disconnection. Current routing protocols usually use geographic information to forward packets. In this paper, we propose a traffic adaptive routing scheme called TAGR for inter-vehicle communication in urban scenarios. The key differences between TAGR and other geographic protocols are the process of real-time vehicle traffic estimation and Traffic adaptive selection of optimal route. Firstly, the position data that our location service provides is analyzed and aggregated to estimate vehicle densities of roads. Secondly, TAGR considers the movements of nodes (vehicles) and takes advantage of the predictable mobility pattern of vehicles. TAGR utilizes traffic information and movement predication to create adaptive connectivity model which improves the routing process by selecting the most stable route. Simulations in realistic city environments are conducted to compare the proposed protocol with GSR and GyTAR protocols. The results show that TAGR outperforms the others in terms of data delivery ratio and average delay
[Show abstract][Hide abstract] ABSTRACT: Location based routing protocols are often used to deliver packets in VANET for the sake of scalability and lower overhead. Before exchanging information between moving vehicles, the location of destination node should be discovered. However, the existing location service employed in MANET is not very suitable for vehicular ad hoc network. In this paper, a vehicle location service protocol (VLS) is proposed to support inter-vehicle communication (IVC) in cities. The information in digital maps is utilized to help realize location service. We present a method of partitioning the network and constructing distributed location servers, which can avoid selecting servers in void areas and decrease the average location discovery delay. In order to reduce the location update cost, forwarding trees and adaptive update policies are used to send messages. In addition, the cost of location update and discovery delay can be balanced through different parameters setting for a given network. Different scenarios are simulated to compare the performance of GLS, GHLS and VLS. The experiment results show that VLS outperforms others in urban environments.
Communications, 2009. ICC '09. IEEE International Conference on; 07/2009
[Show abstract][Hide abstract] ABSTRACT: VANET is an ad hoc network composed of highly mobile vehicle nodes. Many routing protocols utilize traffic information as a critical metric for determining optimal message forwarding path. The existing traffic information systems are not suitable for routing decision either because of the huge development and maintenance cost or due to the insufficient information provision. In this paper, a new distributed approach of traffic estimation is presented, where the position data that our location service provides is mined to build traffic information system. Based on the location information of vehicles, the traffic density of whole network can be evaluated in each small region separately. The node distributions that held by location servers in street segments are exploited and aggregated together to calculate the overall traffic information. The analyses and simulations about the update cost and query delay for both location service and traffic information system are given.
Proceedings of the 16th International Conference on Networks, ICON 2008, December 12-14, 2008, held at India Habitat Centre, New Delhi, India; 01/2008
[Show abstract][Hide abstract] ABSTRACT: Hybrid content distribution network (HCDN), integrating complementary advantages of CDN and P2P, is used to improve efficiency of large-scale content distribution. In this paper, to achieve in-depth understanding of HCDN¿s effectiveness, we carry out a detailed performance evaluation based on deterministic fluid model. We also provide numeric results of HCDN, comparing with conventional CDN and P2P. Some performance metrics are taken into account in our analysis, such as the evolution of the number of seeds and downlowders, the service capacity of system and the average downloading time.
The Second International Conference on Future Generation Communication and Networking, FGCN 2008, Volume 1, Main Conference, Hainan Island, China, December 13-15, 2008; 01/2008