3953733
TCP-Real: receiver-oriented congestion control
We introduce a receiver-oriented approach to congestion control, demonstrated by an experimental protocol, TCP-Real. The protocol allows for a measurement-based transmission strategy, which complements the "blind" increase/ decrease window adjustments. Owing to its design, the protocol displays an inherent property to produce comprehensive dynamics in heterogeneous environments with wired or wireless networks and delay-sensitive or -tolerant applications. TCP-Real controls congestion as standard TCP does. However, its receiver-oriented nature and its "wave" communication pattern allow for two amending mechanisms: (i) congestion avoidance, which reduces unnecessary transmission gaps that hurt the performance of time-constrained applications, and (ii) advanced error detection and classification, which designates recovery tactics responsive to the nature of the errors, thereby enhancing the protocol performance over wireless links or asymmetric paths.We detail the protocol mechanisms and specification and we report extensively on the comparative fairness and efficiency evaluation of standard TCP, TCP-Real, and TCP-friendly protocols for both delay-tolerant and -sensitive applications and in both wired and wireless networks.
1830896
A Communication Virtual Machine
The convergence of data, voice and multimedia communication over digital networks, coupled with continuous improvement in network capacity and reliability has significantly enriched the ways we communicate. However, the stovepipe approach used to develop today's communication applications and tools results in rigid technology, limited utility, lengthy and costly development cycle, difficulty in integration, and hinders innovation. In this paper, we present a fundamentally different approach, which we call communication virtual machine (CVM) to address these problems. CVM provides a user-centric, model-driven approach for conceiving, synthesizing and delivering communication solutions across application domains. We argue that CVM represents a far more effective paradigm for engineering communication solutions. The concept, architecture, modeling language, prototypical design and implementation of CVM are discussed
3967435
Experimental Evaluation of Red in Heterogeneous Environments
33105882
CyberBridges A Model Collaboration Infrastructure for e-Science
The "CyberBridges" pilot project is an innovative model for creating a new generation of scientists and engineers who are capable of fully integrating cyberinfrastructure into the whole educational, professional, and creative process of their respective disciplines. CyberBridges augments graduate student education to include a foundation of understanding in advanced networking and grid infrastructure for high performance computing, and bridges the divide between the information technology community and diverse science and engineering disciplines. We demonstrate the effectiveness of CyberBridges by providing four case studies. Groundwork has begun to extend the outreach of CyberBridges for international research and education collaborations.
3978452
The Interaction Between Window Adjustment Strategies and Queue Management Schemes
In this paper, we investigate extensively the joint network dynamics with different AIMD window-adjustment parameters on end-hosts, and different queue management schemes (i.e. DropTail vs. RED) in routers. We reveal that with DropTail buffer, although smooth TCPs causes less queuing-delay jitter, its average queuing delay is significantly higher than that of responsive TCPs. The direct implication of this discovery is that when mobile users of media-streaming and short messages share a bottleneck link, the energy consumption for sending short messages can increase severely if media-streaming users adopt smooth TCPs. With RED, on the other hand, smooth TCPs not only lead to smaller queue oscillation, the average/max queue length is smaller as well.
1383951
Improving TCP smoothness by synchronized and measurement-based congestion avoidance
In this paper, we observe that although multiplicative decrease is necessary to accomplish fairness in congestion control, it does not inevitably sacrifice system throughput, as long as the system operates between the knee and the cliff, according to an equation. However, even when the system throughput is relatively stable, end users of real-time applications do not necessarily experience a smooth traffic, mainly caused by the unsynchronized window adjustments due to random congestion indications. We analyzed and evaluated the negative impact of random window adjustments on smoothness, short-term fairness, and even long-term fairness measured by a novel fairness metric defined in this paper. Therefore, we propose an experimental congestion avoidance mechanism to improve TCP smoothness for media-streaming applications. The mechanism relies on a fine-grained RTT estimation to measure the network condition, and coordinates the upward and backward window adjustments to abolish the damage of unsynchronized window control. Congestive packet drops are reduced by a new control parameter g, and the bottleneck queue length can also be controlled in an end-to-end way. Simulation results confirm that the new mechanism enhance significantly the smoothness and fairness, without a cost of responsiveness. In fact, by enabling a new parameter d, the responsiveness can be even enhanced when the bandwidth is under-utilized.
206924421
Classification of access network types: Ethernet wireless LAN, ADSL, cable modem or dialup?
Ethernet, wireless LAN, ADSL, cable modem and dialup are common access networks, but have dramatically different characteristics. Fast and accurate classification of access network type can improve protocol or application performance significantly. In this paper, we propose a simple and efficient end-end scheme to classify the type of an access network into three categories: Ethernet, wireless LAN and low-bandwidth connection. Our scheme is based on the intrinsic characteristics of the various access networks and utilizes the median and entropy of packet pair inter-arrival times. Extensive experiments show that our scheme obtains accurate classification results in a very short time (10 to 100 seconds).
15005856
Security analysis for key generation systems using face images
In this paper, we analyze the security problem of user information associated key generation (UIAKG) systems. We consider three kinds of attacks from the hacker: the exhaustive search attack, the authentic key statistics attack and the device key statistics attack. Under each attack, we give the estimate of the number of guesses the hacker has to make in order to access the system. Such analysis provides useful guidelines in designing a UIAKG system. The analysis also suggests that a user-dependent UIAKG is more secure than a user-independent one. Two UIAKG systems using face images as inputs are designed and compared to support the above theoretical analysis.
1498226
Approaches to implementing decision aggregation in multi-agent systems
14409052
Shear-resize factorizations for fast image registration
Owing to its effectiveness and simplicity, intensity-based method works well for registration of images. However, it needs a large amount of computation for geometric transformation. In this paper, we present two shear-resize matrix factorizations to accelerate the transformation. A transform matrix can be factorized into two shears and a fixed non-uniform resize, or three shears and a customizable resize. A customizable resize can be uniform in all dimensions or scaling just in one dimension. Shears can be implemented very fast by memory-shift, and a resize can be done by simple axis-aligned interpolation. The factorizations can be applied to both rigid-body and affine transformations. Their efficiency is performed by experiments on some standard test images and fingerprint images. The methods are quite promising for hardware implementation, and can also be extended to 3D or higher dimensional fast geometric transformation.
6161007
Light field capturing with lensless cameras
We introduce a novel approach to capturing light field with lensless cameras. By moving the cameras back and forth, we capture a set of images. We show that it is possible to reconstruct the light field from these blurry images. The problem is formulized in a way similar to computer tomography, so that the light field can be reconstructed using existing algorithms. The light field can then be used to render 3D scenes. Synthetic examples are presented to show the effectiveness of the proposed method.