This paper investigates the use of WiFi and mobile device-to-device networks, with vehicular ad hoc networks being a typical example, as a complementary means to offload and reduce the traffic load of cellular networks. A novel cooperative content dissemination strategy is proposed for a heterogeneous network consisting of different types of devices with different levels of mobility, ranging from static WiFi access points to mobile devices such as vehicles. The proposed strategy offloads a significant proportion of data traffic from cellular networks to WiFi or device-to-device networks. Detailed analysis is provided for the content dissemination process in heterogeneous networks adopting the strategy. On that basis, the optimal parameter settings for the content dissemination strategy are discussed. Simulation and numerical studies show that the proposed strategy effectively reduces data traffic for cellular networks while guaranteeing successful content delivery.
As vehicular networks form an important class of mobile networks, there is significant research on content dissemination in vehicular networks @cite_1 . Wireless access through vehicle-to-roadside communications can be used in public transport vehicles for streaming applications, e.g., videos and interactive advertisements. As pointed out in @cite_20 , it is challenging to develop an efficient wireless access scheme that minimises the cost of wireless connectivity for downloading data. There are also some empirical studies on content dissemination methods for vehicular networks @cite_4 .
@cite_4 @cite_1 @cite_20
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Content-based information dissemination has a potential number of applications in vehicular networking, including advertising, traffic and parking notifications and emergency announcements. In this paper we describe a protocol for content based information dissemination in hybrid (i.e., partially structureless) vehicular networks. The protocol allows content to “stick” to areas where vehicles need to receive it. The vehicle's subscriptions indicate the driver's interests about types of content and are used to filter and route information to affected vehicles. The publications, generated by other vehicles or by central servers, are first routed into the area, then continuously propagated for a specified time interval. The protocol takes advantage of both the infrastructure (i.e., wireless base stations), if this exists, and the decentralized vehicle-to-vehicle communication technologies. We evaluate our approach by simulation over a number of realistic vehicular traces based scenarios. Results show that our protocol achieves high message delivery while introducing low overhead, even in scenarios where no infrastructure is available. Future vehicular networks are expected to deploy short-range communication technology for inter-vehicle communication. In addition to vehicle-to-vehicle communication, users will be interested in accessing the multimedia-rich Internet from within the vehicular network. This motivates a compelling application of Co-operative Networking in the Vehicular Ad-Hoc network where the Ad Hoc network extends and complements the Internet. The broadcast nature of the wireless medium drives us to explore different design paradigms from the ones used in typical wired settings.A new paradigm in content delivery on the Internet using peer-peer swarming protocols is emerging [1,2]. We propose SPAWN, a simple cooperative strategy for content delivery in future vehicular networks. We study the issues involved in using such a strategy from the standpoint of Vehicular Ad-Hoc networks. Several enhancements to a popular swarming protocol (BitTorrent) are discussed including a gossip mechanism that leverages the inherent broadcast nature of the wireless medium, and a piece-selection strategy that uses proximity to exchange pieces quicker. Preliminary results show that SPAWN increases the perceived performance of the network, resulting in faster downloads for popular files. We consider a system where users aboard communication-enabled vehicles are interested in downloading different contents from Internet-based servers. This scenario captures many of the infotainment services that vehicular communication is envisioned to enable, including news reporting, navigation maps, and software updating, or multimedia file downloading. In this paper, we outline the performance limits of such a vehicular content downloading system by modeling the downloading process as an optimization problem, and maximizing the overall system throughput. Our approach allows us to investigate the impact of different factors, such as the roadside infrastructure deployment, the vehicle-to-vehicle relaying, and the penetration rate of the communication technology, even in presence of large instances of the problem. Results highlight the existence of two operational regimes at different penetration rates and the importance of an efficient, yet 2-hop constrained, vehicle-to-vehicle relaying. We study the performance of collaborative vehicular content dissemination, where the content is distributed within the network by vehicle-to-vehicle opportunistic communications and the vehicle nodes are equipped with directional antennas. Through analysing a large real-world vehicle trace, we adopt an accurate mobility model of Levy-walk to set up the realistic vehicular network simulation environment. Using a fluid approximation, we derive a theoretical model to depict the system performance of content dissemination time. The accuracy of the proposed analysis is confirmed by simulation results, which also show that the directional antenna performs better than the omni-directional antenna in our considered scenario, especially when the antenna beam is well scheduled with small beamwidth and high beam steering rate.