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.

Mobility modeling is an essential component of wireless and mobile networking research. It assists planning, developing and evaluating protocols and mobile systems. A simulated mobile world provides flexibility for constructing scenarios that closely resemble the real world. Our proposed mobility model emphasizes humans' social roles when making movement decisions. Our model, the 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 paper uses a constructive approach to define functional components of the Agenda Driven Mobility Model for building specific real world scenarios and generating motion steps. A variety of real data sources can be used to populate these components. In this sense, the model provides a framework for translating social agendas into a mobile world. In the paper, we utilize National Household Travel Survey (NHTS) information from the U.S. Department of Transportation to obtain activity and dwell time distributions. As an example, we simulate a mobile ad hoc network in an urban scenario, analyzing the geographic features of the network topology generated by the model and the impact of the model on routing performance. Our simulation results suggest that social roles and agenda activities tend to cause geographic concentrations, significantly impacting network performance. We conclude that the incorporation of social agendas into mobility modeling produces a performance evaluation that better reflects real world scenarios.

No abstract

Abstract-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 the message overhead to a bounded number. Our approach differs from a few 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 copies of the message 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 controlled opportunistically-forwarding schemes and has a significantly smaller routing overhead than the pure flooding schemes.

Abstract-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 transmissions 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.