We consider a vehicular content replication system which makes use of the deployed Access Points (APs) to maximize the vehicular download progress of delay-tolerant contents through replication in the APs' local storage. The transient connection period between the vehicle and the AP makes it difficult for the vehicle to download the entire file requested and thus the content retrieval is usually across several APs. We propose an efficient and distributed replication algorithm explicitly taking into account the content popularity, vehicle-AP contact pattern, and content availability among correlated APs. Simulation based on real vehicular trace proves the effectiveness of the proposed replication system. The performance in terms of download rate and completion ratio has at least 15% to 20% improvement against the algorithms under comparison.

For better road safety and driving experience, content distribution for vehicle users through roadside Access Points (APs) becomes an important and promising complement to 3G and other cellular networks. In this paper, we introduce Cooperative Content Distribution System for Vehicles (CCDSV) which operates upon a network of infrastructure APs to collaboratively distribute contents to moving vehicles. CCDSV solves several important issues in a practical system, like the robustness to mobility prediction errors, limited resources of APs and the shared content distribution. Our system organizes the cooperative APs into a novel structure, namely, the contact map which is based on the vehicular contact patterns observed by APs. To fully utilize the wireless bandwidth provided by APs, we propose a representative-based prefetching mechanism, in which a set of representative APs are carefully selected and then share their prefetched data with others. The selection process explicitly takes into account the AP's storage capacity, storage status, inter-APs bandwidth and traffic loads on the backhaul links. We apply network coding in CCDSV to augment the distribution of shared contents. The selection of shared contents to be prefetched on an AP is based on the storage status of neighboring APs in the contact map in order to increase the information utility of each prefetched data piece. Through extensive simulations, CCDSV proves its effectiveness in vehicular content distribution under various scenarios.

For vehicle users, content distribution through roadside APs is an important complement to that through 3G and other cellular networks. However, the unique features of such access scheme pose many challenges on effectively satisfying vehicles' data request. This paper proposes a cooperative content distribution system for vehicles(CCDSV), based on the network-coding, vehicle-AP contact prediction, and data-prefetching techniques. CCDSV uses network coding to distribute encoded data for the effective sharing of popular contents. CCDSV predicts the vehicle's future contact APs and adaptively prefetches requested data in advance before vehicle's arrival. The proposed system is implemented into ns-2 simulator and demonstrates its effectiveness in terms of throughput, reduced traffic load, and download volume.

In this paper, we propose a novel Intrusion Detection System (IDS), Court-like Cluster-based IDS (CCIDS), to secure routing protocols in Mobile Ad Hoc Networks (MANETs). After the network is divided into one-hop clusters, each of these clusters performs similar functions as a court in real-life, such as accusation, investigation and defence. We show that court like IDS is effective in many aspects, especially the capability to prevent malicious alerts and reduce false positive rate. To further prove its effectiveness, we then apply CCIDS in securing the Optimized Link State Routing (OLSR) protocol to solve two most severe attacks-link spoofing and link deletion. Through extensive simulation, four performance parameters, namely, detection rate, false positive rate, detection delay, and communication overhead are evaluated.