Qunwei Zheng

Recent advances in mobility modeling for mobile ad hoc network research

In this paper, we survey recent advances in mobility modeling for mobile ad hoc network research. The advances include some new mobility models and analysis of older mobility models. First we classify mobility models into three categories according to the degree of randomness. We introduce newly proposed mobility models in each of these categories. Next we discuss analysis for existing mobility models. We describe the analysis work in three parts. The first part is the statistical properties of the most widely used Random Waypoint Model. The second part describes the mobility metrics that aim to capture the characteristics of different mobility patterns. The last part is the impact of mobility models on the performance of protocols. We also describe some possible future work.

Effective probabilistic approach protecting sensor traffic

Sensor networks are often deployed in environments where malicious nodes present. Among all possible forms of the attacks threatening the sensor networks, in this work, we focus on traffic analysis attacks. Typically, in performing traffic analysis, an attacker will eavesdrop on-going wireless transmission and analyze contents and timing instances of the transmissions so to infer critical events or to trace valuable assets in the network (e.g. data sources or sinks). The paper presents a probabilistic approach to shape the sensor network traffic to decorrelate time instances in transmissions. The security properties of the approach are studied both analytically and empirically, showing strong protection in high probability

An agenda based mobility model

Mobility modeling is important in wireless and mobile networking research due to the fact that few real large scale networks is available for performance evaluation. While existing models only take the geographical movements into consideration, we emphasize in our model the importance of humans social roles. We use a persons social activities to drive and model a nodes movements. In this paper, we propose an agenda based mobility model which combine both the social activities and the geographic movements. In the design, we use a constructive modeling approach to allow the model to well conform to the real world and to be easy to use. According to our model, each node moves based on its individual agenda, which includes all the activities (when, where and what) on a specific day. To proceed from one activity to another, a node moves from one road address to another address. In deciding each agenda item, we use NHTS survey data to obtain activity distribution, occupation distribution and dwell time distribution. We use simulation to show the network topology generated by the model and ad hoc network routing performance impacted by the model.

Agenda driven mobility modelling

Mobility modelling is an essential component of wireless and mobile networking research. Our proposed Agenda Driven Mobility Model takes into consideration a persons 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.

SMART: A selective controlled-flooding routing for delay tolerant networks

Delay-Tolerant network (DTN) is a network in which no simultaneous end-to-end path exists. And the messages delivered in the DTN usually have large delivery latency due to network partition. These special characteristics make DTN routing a challenging problem. In this paper, we propose a DTN routing protocol SMART. SMART uses travel companions of the destinations (i.e. nodes that frequently meet the destination) to increase the delivery opportunities. In the first phase of SMART, a fixed number of copies of a message are injected into the network to forward the message to the companions of the destination. In the second phase of SMART, a companion of the destination only forwards the message to a fixed number of the destination’s companions. Our analysis and simulation results show that SMART has a higher delivery ratio and smaller delivery latency than opportunistically controlled-flooding schemes and has a significantly smaller routing overhead than pure flooding schemes.

A Hierarchical Anonymous Routing Scheme for Mobile Ad-Hoc Networks

Privacy and anonymity are critical security issues to many large-scale MANET applications such as military communication networks. These applications are more likely deploying the networks heterogeneously and hierarchically due to administrative needs or routing efficiency. When the size of the network scales up, the routing overhead incurred by existing flat anonymous routing protocols increases fast as the required number of public key operations increases. This results in deteriorated routing and data communication performance. In this paper, we introduce a novel hierarchical anonymous on-demand routing protocol tackling this limitation. In addition to guaranteeing routing and data delivering security, the scheme provides two levels of anonymity: intra-group and inter-group. By exploiting the hierarchical network structure, it effectively controls computational overhead while preserving anonymity, hence accommodates to larger-scale MANETs

Selective Message Forwarding in Delay Tolerant Networks

It is challenging to deliver messages in a network where no instant end-to-end path exists, so called delay-tolerant network (DTN). Node encounters are used for message forwarding. In this paper, we propose a DTN routing protocol SMART. SMART utilizes the travel companions of the destinations (i.e. nodes that frequently meet the destination) to increase the delivery opportunities while limiting message overhead to a bounded number. Our approach differs from related work in that it does not propagate node encounter history nor the delivery probabilities derived from the encounter history. In SMART, a message source injects a fixed number of message copies into the network to forward the message to a companion of the destination, which only forwards the message to a fixed number of the destination’s companions. Our analysis and simulation results show that SMART has a higher delivery ratio and a smaller delivery latency than the schemes that only use controlled opportunistically-forwarding mechanism and has a significantly smaller routing overhead than a pure flooding scheme.

A Secure Data Transmission Scheme for Mobile Ad Hoc Networks

We propose a secure data transmission scheme that takes advantage of node mobility. The scheme is based on the observation that due to mobility, messages sent at different times are routed through different intermediate nodes. The source divides a message into multiple shares and sends these shares at different times. The destination combines enough shares to recover the original message. Due to mobility, it is high unlikely that an intermediate node is able to collect enough shares. The feasibility of this scheme is analyzed and simulated.

Privacy-Preserving Quick Authentication in Fast Roaming Networks

Vehicular networks will become an important component for information accesses in ones daily life. A vehicular network provides a vehicular user not only chances to communicate with peer vehicles but also to use Internet through roadside access points (APs). During a trip a vehicular user could roam across multiple APs either belong to their home wireless domain or to domains owned by different authorities. This poses challenges on privacy and network performance to the current public wireless network access protocols. In this paper we explore an idea that shifts the paradigm of authentication that goes back to home networks to a paradigm of authentication that performs at the APs. We propose three authentication schemes in realizing the idea. These schemes are designed for preserving users identity and location privacy. They also greatly reduce response time for authentication when roaming. The paper then analyzes the security and privacy properties of these schemes as well as the efficiency of them

Strategies for time-based multi-path secure information disseminations in MANETs

Sending messages securely to protect confidentiality in mobile ad hoc networks is a challenging issue due to the open wireless media, the spacial constraints and the difficulty in establishing strict security mechanisms. To tackle the problem, we have presented a scheme where a source node sends shares of a message at different times. Due to node mobility, the shares will be routed through different intermediate nodes. It is highly unlikely that a particular intermediate node (an eavesdropper) is able to be on (or around) many of these routes and collect enough shares to reconstruct the original message. The scheme is particular suitable for applications that can tolerate long message delays, as those studied in delay tolerant networks. The paper focuses on analyzing the strategies that a node can use in determining the intervals between two shares, and in tuning to applicationspsila requirements on delay bounds. The results provide a guideline for the configuration and the security of the scheme. We further investigate the influence from various mobility models on the security property. The results show big differences among the models and the practical aspect of the scheme. In all, our proposed scheme provides a valuable alternative for delay tolerant applications to enhance message confidentiality.