Showing papers by "Xiaoyan Hong published in 2010"

Secure, selective group broadcast in vehicular networks using dynamic attribute based encryption

Abstract: Ciphertext-policy attribute-based encryption (CP-ABE) provides an encrypted access control mechanism for broadcasting messages. Basically, a sender encrypts a message with an access control policy tree which is logically composed of attributes; receivers are able to decrypt the message when their attributes satisfy the policy tree. A user's attributes stand for the properties that he currently owns. A user should keep his attributes up-to-date. However, this is not easy in CP-ABE because whenever one attribute changes, the entire private key, which is based on all the attributes, must be changed. In this paper, we introduce fading function, which renders attributes “dynamic” and allows users to update each attribute separately. We study how choosing fading rate for fading function affects the efficiency and security. We also compare our design with CP-ABE and find our scheme performs significantly better under certain circumstance.

Situation-aware trust architecture for vehicular networks

Abstract: We present a new trust architecture-Situation-Aware Trust-to address several important trust issues in vehicular networks SAT includes three main components: an attribute-based policy control model for highly dynamic communication environments, a proactive trust model to build trust among vehicles, and prevent the breakage of existing trust, and an email-based social network trust system to enhance trust and to allow the set up of a decentralized trust framework To deploy SAT, we utilize identity-based cryptography to integrate entity trust, data trust, security policy enforcement, and social network trust, allocating a unique identity, and a set of attributes for each entity We conclude by presenting research challenges and potential research directions that extend this work

Establishing Email-Based Social Network Trust for Vehicular Networks

Abstract: We propose a vehicular network trust model that integrates cryptography-based entity trust and email-based social trust. The entity trust provides security protections such as origin integrity, data integrity, and confidentiality. The social trust provides a level of belief on the data transmitted by an entity. To achieve the email-based social trust, we require each user to run an automated agent that performs trust evaluation checks and processes trust checking requests. The requests are from their highly trusted contacts or through a trusted proxy server maintained by the email service provider. We utilize identity-based cryptography (IBC) to integrate entity trust and social trust. This allows us to use a unique identity (e.g., an email address) for each entity. Further, we use the IBC based attribute based cryptography to develop secure group communications in vehicular networks. Finally, we present research challenges and potential research directions to extend this work.

Agenda driven mobility modelling

Abstract: Mobility modelling is an essential component of wireless and mobile networking research. Our proposed Agenda Driven Mobility Model takes into consideration a person's social activities in the form of agenda (when, where and what) for motion generation. The model provides a framework for translating social agendas into a mobile world. Using the data from National Household Travel Survey (NHTS) of the US Department of Transportation, our simulation results suggest that social roles and agenda activities tend to cause geographic concentrations and significantly impact network performance. The model is in a position of better reflecting real world scenarios.

Exploring multiple radios and multiple channels in wireless mesh networks [Accepted from Open Call]

Abstract: Much research has been performed investigating the challenging issue of efficiently utilizing the network-wide capacity available in the multihop wireless mesh networks with multiple radios and multiple channels. In this work, multihop routing and channel assignment are intertwined issues. In this article we present summaries of this work based on two broad categorizations in terms of algorithm features: centralized and distributed approaches. Due to the multiple dimensions of the topics, we subgroup the papers in terms of how the interactions between routing and channel assignments are treated. They include channel assignment based on the given connectivity graph, joint design of routing and channel assignment, routing with localized considerations on channel selection, and channel assignment with local channel usage and traffic load information. With the centralized approach, the schemes are able to target optimal channel assignment and joint design on both channel assignment and routing issues. In the distributed approach, the papers take steps focused on either route metrics or channel scheduling based on localized information about the links at each node. Comparisons and open research issues are given as the conclusion.

Latency Analysis for Thrown Box Based Message Dissemination

Abstract: In delay tolerant network, message delivery can be inspired by biological communication models in realizing encountering and delivering. One way of communications can be through "thrown box" where the messages can be left and collected by different nodes in mimicking pheromone-based communications. In thrown box based model, the box is viewed as message relay and the delivery rate is enhanced by spreading a message at as many boxes as possible. Both the life time of message left at the boxes and message leaving preference will have a significant influence on the latency and delivery ratio in message dissemination. In this paper, we model the latency problem as discrete time Markov Chain and further derive the time distribution of first contact between the message and collector. By varying the parameters of message leaving probability and initial environment condition, the latency related results are studied.

Delay analysis of Wireless Ad Hoc networks: Single vs. multiple radio

Abstract: Due to the self organizing characteristic of Ad Hoc network, it is difficult to adopt traditional delay measurement techniques in a multi hop Wireless Mesh network (WMN). This problem is much more complicated in multi-radio environment because of the mutual interferences that contribute significantly to the overall delay. We present an experimental methodology to obtain an estimate of average intra-node delay and inter-node delay for packets of variable payload size in both single radio and multi-radio environment without the constraint of clock synchronization between the nodes. Our results provide insights on comparing performances between single and multi-radio environment with some interesting findings like periodic nature for intra-node delay with oscillating frequency distribution. Finally our statistical analysis validates the linear relationship between end to end delay, intra-node delay and inter-node delay.

Critical Phase of Connectivity in Wireless Network Expansion

Abstract: In this paper, we study the transition phase in the network connectivity. We focus on the critical time points that mark the network transformation from partition to connected state following a growth of node density. The percolation theory is used to analyze the relationship between the density increase process and the connectivity transition. Specifically, we derive the lower bound and the upper bound of critical density points against node transmission range. We also use three growth functions of node density to obtain the first connection time and the total connection time which denote the critical points when the node densities reach the lower bound and upper bound of critical value respectively. The simulation demonstrates the evolution of network in terms of the connectivity and gives the connection times with three different growth models.

Handshake time and transmission rate of 802.11g measurement in vehicular networks

Abstract: Wireless network access from moving vehicles can be challenged by many factors such as connection opportunities, mobility, handshake phase, and data sizes, etc. The handshake time and transmission rate can be influenced differently in vehicle-to-roadside networks than a static wireless LAN access. The radio signal strength changes and Doppler shift occur when the vehicle is moving. Switching among APs could cause significant connection stale, which could have a major impact on the handshake phase and transmission rate. The purpose of our paper is to enhance the understanding of these influential factors and study the feasibility of mobile vehicle access for a hybrid environment that contains sparse and dense access point deployments. Experiment data was collected in a moving vehicle, which traveled around the campus of the university. In the data analyze part, the above factors are analyzed for packet inter-arrival time, response time and transmission rate; Our main results are focused in security enabled protocols such as HTTPS and SSH, as well as TCP file transmission. Our data shows that IEEE 802.11g is still weak in supporting mobile vehicle access to the Wireless LAN. We expect that IEEE 802.11p, designed specifically for vehicle networks, can provide better mobile services.