10445420
Modeling and Predicting Future Trajectories of Moving Objects in a Constrained Network
Advances in wireless sensor networks and positioning technologies enable traffic management (e.g. routing traffic) that uses real-time data monitored by GPS-enabled cars. Location management has become an enabling technology in such application. The location modeling and trajectory prediction of moving objects are the fundamental components of location management in mobile locationaware applications. In this paper, we model the road network and moving objects in a graph of cellular automata (GCA), which makes full use of the constraints of the network and the stochastic behavior of the traffic. A simulation-based method based on graphs of cellular automata is proposed to predict future trajectories. Our technique strongly differs from the linear prediction method, which has low prediction accuracy and requires frequent updates when applied to real traffic with velocity changes. The experiments, carried on two different datasets, show that the simulation-based prediction method provides higher accuracy than the linear prediction method.
7794101
Effective Density Queries for Moving Objects in Road Networks
Recent research has focused on density queries for moving objects in highly dynamic scenarios. An area is dense if the number of moving objects it contains is above some threshold. Monitoring dense areas has applications in traffic control systems, bandwidth management, collision probability evaluation, etc. All existing methods, however, assume the objects moving in the Euclidean space. In this paper, we study the density queries in road networks, where density computation is determined by the length of the road segment and the number of objects on it. We define an effective road-network density query guaranteeing to obtain useful answers. We then propose the cluster-based algorithm for the efficient computation of density queries for objects moving in road networks. Extensive experimental results show that our methods achieve high efficiency and accuracy for finding the dense areas in road networks.
987186
Implementing Minimized Multivariate PKC on Low-Resource Embedded Systems
Multivariate (or $\mathcal{MQ}$) public-key cryptosystems (PKC) are alternatives to traditional PKCs based on large algebraic structures (e.g., RSA and ECC); they usually execute much faster than traditional PKCs on the same hardware. However, one major challenge in implementing multivariates in embedded systems is that the key size can be prohibitively large for applications with stringent resource constraints such as low-cost smart cards, sensor networks (e.g., Berkeley motes), and radio-frequency identification (RFID). In this paper, we investigate strategies for shortening the key of a multivariate PKC. We apply these strategies to the Tame Transformation Signatures (TTS) as an example and quantify the improvement in key size and running speed, both theoretically and via implementation. We also investigate ways to save die space and energy consumption in hardware, reporting on our ASIC implementation of TTS on a TSMC 0.25μm process. Even without any key shortening, the current consumption of TTS is only 21 μA for computing a signature, using 22,000 gate equivalents and 16,000 100-kHz cycles (160 ms). With circulant-matrix key shortening, the numbers go down to 17,000 gates and 4,400 cycles (44 ms). We therefore conclude: besides representing a future-proofing investment against the emerging quantum computers, multivariates can be immediately useful in niches.
1963845
Testbed evaluation of navigation and text display techniques in an information-rich virtual environment
The fundamental question for an information-rich virtual environment is how to access and display abstract information. We investigated two existing navigation techniques: hand-centered object manipulation extending ray-casting (HOMER) and go-go navigation, and two text layout techniques: within-the-world display (WWD) and heads-up display (HUD). Four search tasks were performed to measure participants' performance in a densely packed environment. HUD enabled significantly better performance than WWD and the go-go technique enabled better performance than the HOMER technique for most of the tasks. We found that using HOMER navigation combined with the WWD technique was significantly worse than other combinations for difficult naive search tasks. Users also preferred the combination of go-go and HUD for all tasks.
33085304
An Intuitive and Effective New Representation for Interconnection Network Structures
Based on the classical voltage graph theory, we develop a new representation scheme for interconnection network structures. We show that all popular interconnection networks have very simple and intuitive representations under the new scheme. The new representation scheme offers powerful tools for the study of network routing and network emulation. As examples, we present simple constructions for optimal network emulations from cube-connected cycles networks to butterfly networks, and from butterfly networks to hypercube networks.
40634947
Experiments Study on a Dynamic Priority Scheduling for Wireless Sensor Networks
Wireless Sensors Networks (WSNs) represent a new generation of embedded systems, which deploy wireless ad hoc communication mechanisms to route a sensory data from the originator sensor node to the base station. One of the most important issues in wireless sensor networks is to support real-time QoS, which is fundamentally a challenging problem. In this paper, we introduce EDBP scheduling algorithm for sensor network along with a MAC protocol based on the dynamic priority assignment EDBP. Two different platforms based experiment projects are designed to test our proposal.
7679474
Delay Reduction Techniques for Playout Buffering
Receiver synchronization of continuous media streams is required to deal with delay differences and variations resulting from delivery over packet networks such as the Internet. This function is commonly provided using per-stream playout buffers which introduce additional delay in order to produce a playout schedule which meets the synchronization requirements. Packets which arrive after their scheduled playout time are considered late and are discarded. In this paper, we present the Concord algorithm, which provides a delay-sensitive solution for playout buffering. It records historical information and uses it to make short-term predictions about network delay with the aim of not reacting too quickly to short-lived delay variations. This allows an application-controlled tradeoff of packet lateness against buffering delay, suitable for applications which demand low delay but can tolerate or conceal a small amount of late packets. We present a selection of results from an extensive evaluation of Concord using Internet traffic traces. We explore the use of aging techniques to improve the effectiveness of the historical information and hence, the delay predictions. The results show that Concord can produce significant reductions in buffering delay and delay variations at the expense of packet lateness values of less than 1%.