Performance and policy dimensions in internet routing

The Internet Routing Project, referred to in this report as the 'Highball Project', has been investigating architectures suitable for networks spanning large geographic areas and capable of very high data rates. The Highball network architecture is based on a high speed crossbar switch and an adaptive, distributed, TDMA scheduling algorithm. The scheduling algorithm controls the instantaneous configuration and swell time of the switch, one of which is attached to each node. In order to send a single burst or a multi-burst packet, a reservation request is sent to all nodes. The scheduling algorithm then configures the switches immediately prior to the arrival of each burst, so it can be relayed immediately without requiring local storage. Reservations and housekeeping information are sent using a special broadcast-spanning-tree schedule. Progress to date in the Highball Project includes the design and testing of a suite of scheduling algorithms, construction of software reservation/scheduling simulators, and construction of a strawman hardware and software implementation. A prototype switch controller and timestamp generator have been completed and are in test. Detailed documentation on the algorithms, protocols and experiments conducted are given in various reports and papers published. Abstracts of this literature are included in the bibliography at the end of this report, which serves as an extended executive summary

Gradient-based Edge Detection Using Nonlinear Edge-enhancing Prefilters

This correspondence examines the use of nonlinear edge enhancers as prefilters for edge detectors. The filters are able to convert smooth edges to step edges and suppress noise simultaneously. Thus, false alarms due to noise are minimized and edge gradient estimates tend to be large and localized. This leads to significantly improved edge maps

LUM Filters: A Class of Rank-order-based Filters for Smoothing and Sharpening

A new class of rank-order-based filters, called lower-upper-middle (LUM) filters, is introduced. The output of these filters is determined by comparing a lower- and an upper-order statistic to the middle sample in the filter window. These filters can be designed for smoothing and sharpening, or outlier rejection. The level of smoothing done by the filter can range from no smoothing to that of the medianfilter. This flexibility allows the LUM filter to be designed to best balance the tradeoffs between noisesmoothing and signal detail preservation. LUM filters for enhancing edge gradients can be designed to be insensitive to low levels of additive noise and to remove impulsive noise. Furthermore, LUM filters do not cause overshoot or undershoot. Some statistical and deterministic properties of the LUM filters are developed, and a number of experimental results are presented to illustrate the performance. These experiments include applications to 1D signals and to images

Reliable Blind Information Hiding for Images

. In this paper we present a new method for reliable blind image steganography that can hide and recover a message of substantial length within digital imagery while maintaining the original image size and dynamic range. Image processing, error-control coding, and spread spectrum techniques are utilized to conceal hidden data and the performance of the technique is illustrated. The message embedded by this method can be in the form of text, imagery, or any other digital signal. Applications for such a data-hiding scheme include in-band captioning, hidden communication, image tamperproofing, authentication, embedded control, and revision tracking. 1 INTRODUCTION Digital steganography, or information hiding, schemes can be characterized by utilizing the theories of communication [1]. The parameters of information hiding such as the amount of data bits that can be hidden, the perceptibility of the message, and its robustness to removal can be related to the characteristics of communicati..

Capacity of the Additive Steganographic Channel

Many digital steganographic systems employ the capacity of an additive white Gaussian noise (WGN) channel as a performance metric. We present results that show that this capacity metric understates the capacity potential of these systems and propose a more accurate measure based on the arbitrary noise channel. This measure is compared to the capacity of the additive WGN channel and the performance of an actual image steganographic system. I. INTRODUCTION At times when we communicate, we prefer that only the intended recipient have the ability to decipher the content of the communication. We want to keep our message secret. A common solution to this problem is the use of encryption to obscure the information content of the message. Instances also exist where we would prefer that the entire communication process be hidden. In this case, steganographic techniques can be used to hide or cover the existence of communication with other data (intuitively referred to as cover data). Consider..

Highball: a high speed, reserved-access, wide area network

This document describes a network architecture called Highball and a preliminary design for a prototype, wide-area data network designed to operate at speeds of 1 Gbps and beyond. It is intended for applications requiring high speed burst transmissions where some latency between requesting a transmission and granting the request can be anticipated and tolerated. Examples include real-time video and disk-disk transfers, national filestore access, remote sensing and similar applications. The network nodes include an intelligent crossbar switch, but have no buffering capabilities; thus, data must be queued at the end nodes. There are no restrictions on the network topology, link speeds or end-end protocols. The end systems, nodes and links can operate at any speed up to the limits imposed by the physical facilities. This document presents an overview of an initial design approach and is intended as a benchmark upon which a detailed design can be developed. It describes the network architecture and proposed access protocols, as well as functional descriptions of the hardware and software components that could be used in a prototype implementation. It concludes with a discussion of additional issues to be resolve in continuing stages of this project