Abstract-The effective inter-vehicle transmission of content files, e.g., images, music and video clips, is the basis of media communications in vehicular networks, such as social communications and video sharing. However, due to the presence of diverse node velocities, severe channel fadings and intensive mutual interferences among vehicles, the inter-vehicle or vehicle-to-vehicle (V2V) communications tend to be transient and highly dynamic. Content transmissions among vehicles over the volatile and spotty V2V channels are thus susceptible to frequent interruptions and failures, resulting in many fragment content transmissions which are unable to finish during the connection time and unusable by on-top media applications. The interruptions of content transmissions not only lead to the failure of media presentations to users, but the transmission of the invalid fragment contents would also result in the significant waste of precious vehicular bandwidth. On addressing this issue, in this work we target on provisioning the integrity-oriented inter-vehicle content transmissions. Given the initial distance and mobility statistics of vehicles, we develop an analytical framework to evaluate the data volume that can be transmitted upon the short-lived and spotty V2V connection from the source to the destination vehicle. Provided the content file size, we are able to evaluate the likelihood of successful content transmissions through the model. Based upon this analysis, we propose an admission control scheme at the transmitters, that filters the suspicious content transmission requests which are unlikely to be accomplished over the transient inter-vehicle links. Using extensive simulations, we demonstrate the accuracy of the developed analytical model, and the effectiveness of the proposed admission control scheme. In the simulated scenario, with the proposed admission control scheme applied, it is observed that about 30% of the network bandwidth can be saved for effective content transmissions.

Abstract — In tactical networks, nodes move according to tactical maneuvers and network partitions occur frequently. To mitigate this problem, data replication is commonly used to increase data availability and reduce data access delay. However, different tactical maneuvers lead to different node mobility models, which affect the performance of data replication schemes. In this paper, we comprehensively study the data replication problem in mobile tactical networks. We propose a new intra-group data replication scheme and extensively quantify the effects of mobility on different inter-group data replication schemes from various perspectives. The study is based on several metrics, which include the average access delay and data availability, and the temporal and spatial analysis of these values. Through extensive experiments, we study the effects of three typical mobility models in tactical networks on data replication, and identify the most suitable data replication schemes under various mobility models. I.

Abstract—Mobile Social Network (MSN) with diverse con-nectivity characteristics is a combination of opportunistic net-work and mobile ad hoc network. Since the major difficulty of data forwarding is the opportunistic part, techniques designed for opportunistic networks are commonly used to forward data in MSNs. However, this may not be the best solution since they do not consider the ubiquitous existences of Transient Connected Components (TCCs), where nodes inside a TCC can reach each other by multi-hop wireless communications. In this paper, we first identify the existence of TCCs and analyze their properties based on five real traces. Then, we propose TCC-aware data forwarding strategies which exploit the special characteristics of TCCs to increase the contact opportunities and then improve the performance of data forwarding. Trace-driven simulations show that our TCC-aware data forwarding strategies outperform existing data forwarding strategies in terms of data delivery ratio and network overhead. I.

Abstract-Travelers in vehicles often have a strong willingness to share their travel experience and exchange information to each other through social networks, such as Facebook and Twitter. This, however, can be costly due to the limited connections on the road to the Internet. In this paper, we develop Verse to facilitate the social communications among vehicle travelers on highways. Verse enables passengers onboard vehicles to share the content information, such as travel blogs with pictures, among each other using impromptu wireless intervehicle communications. Unlike traditional online social networks, which are built upon reliable internet protocol (IP) networks, vehicular social networks face fundamental challenges in that 1) users are anonymous and strangers to each other and that it is hard to identify potential friends of shared interests and that 2) users communicate through intermittent and unreliable intervehicle connections. On addressing the two challenges, Verse implements a friend recommendation function, which helps passengers efficiently identify potential social friends with both shared interests and relatively reliable wireless connections. In addition, Verse is equipped with a social-aware rate control scheme toward efficient utilization of network bandwidth. Using extensive simulations, we show that the friend recommendation function of Verse can effectively predict the mobility of vehicles to assist in social communication and that the social-aware rate control scheme quickly and efficiently adapts to the vehicle's transmission rate according to their social impact. Index Terms-Proximity social communication, queuing process, vehicular ad hoc network.

safety and non-safety related applications and services to improve the passenger safety and comfort. Due to the space and time dy-namics of moving vehicles, network connectivity is an important performance metric to indicate the quality of the network and the user’s satisfaction. Grouping vehicles into platoons in the highway can improve road safety, reduce fuel consumption, and decrease traffic congestion. In this paper, we study the connectivity charac-teristic of platoon-based VANETs. The connectivity probabilities are analyzed for the Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communication scenarios. The relationships between the connectivity probability and the key parameters are investigated, including the traffic density, the coverage of the ordinary vehicle, the coverage of the platoon, the coverage of the Road Side Unit (RSU), the distance between two adjacent RSUs and the ratio of the platoon in the VANET. The results can help the transport system designer to control the traffic on the highway to satisfy the connectivity requirement. Analysis results show that the connectivity probability can be significantly improved when there are platoons in a network. Keywords-Vehicular Ad Hoc Networks (VANETs); pla-toon; connectivity probability; Vehicle-to-Vehicle (V2V);