We use concepts from communication theory to characterize information hiding schemes: the amount of information that can be hidden, its perceptibility, and its robustness to removal can be modeled using the quantities channel capacity, signal-to-noise ratio, and jamming margin. We then introduce new information hiding schemes whose parameters can easily be adjusted to trade off capacity, imperceptibility, and robustness as required in the application. The theory indicates the most aggressive feasible parameter settings. We also introduce a technique called predistortion for increasing resistance to JPEG compression. Analogous tactics are presumably possible whenever a model of anticipated distortion is available.

In many communication situations, the transmitter and the receiver must be designed without a complete knowledge of the probability law governing the channel over which transmission takes place. Various models for such channels and their corresponding capacities are surveyed. Special emphasis is placed on the encoders and decoders which enable reliable communication over these channels.

This paper presents a new event-based communication model for wireless multi-hop networks of energy-constrained devices such as sensor networks. The network is arranged as an event dissemination tree, with nodes subscribing to the event types they are interested in. An event scheduler dynamically allocates and multiplexes upstream and downstream time slots for each event type. Power consumption among wireless nodes is reduced by allowing each node to power down its radio during the portions of the schedule that do not match its particular event subscription. The event dissemination schedule can be determined in both a centralized and distributed fashion, and is highly dynamic to suit the changing rates at which events are generated and distributed through the network. The paper also presents preliminary performance results that demonstrate the power savings achieved by the proposed protocols.

We consider the use of novel communication tool sets to improve the performance of robust watermarking systems. In particular, we relate the effects of attacks on the watermark to signal interference in a fading environment and employ diversity transmission and channel estimation principles to improve performance. A nonstationary parallel binary symmetric channel (BSC) model of the watermark channel is introduced to more accurately characterize signal tampering and, hence, extract the watermark. Analysis of the system sheds light on novel strategies and domains to embed information to improve the performance of robust data hiding schemes. Simulation and testing verify our theoretical observations.

In this paper we consider the problem of designing a medium access control (MAC) protocol for single-hop wireless networks that is provably robust against adaptive adversarial jamming. The wireless network consists of a set of honest and reliable nodes that are within the transmission range of each other. In addition to these nodes there is an adversary. The adversary may know the protocol and its entire history and use this knowledge to jam the wireless channel at will at any time. It is allowed to jam a (1 − ɛ)-fraction of the time steps, for an arbitrary constant ɛ> 0, but it has to make a jamming decision before it knows the actions of the nodes at the current step. The nodes cannot distinguish between the adversarial jamming or a collision of two or more messages that are sent at the same time. We demonstrate, for the first time, that there is a local-control MAC protocol requiring only very limited knowledge about the adversary and the network that achieves a constant throughput for the non-jammed time steps under any adversarial strategy above. We also show that our protocol is very energy efficient and that it can be extended to obtain a robust and efficient protocol for leader election and the fair use of the wireless channel.

The physical user interface is an increasingly significant factor limiting the effectiveness of our interactions with and through technology. This thesis introduces Electric Field Imaging, a new physical channel and inference framework for machine perception of human action. Though electric field sensing is an important sensory modality for several species of fish, it has not been seriously explored as a channel for machine perception. Technological applications of field sensing, from the Theremin to the capacitive elevator button, have been limited to simple proximity detection tasks. This thesis presents a solution to the inverse problem of inferring geometrical information about the configuration and motion of the human body from electric field measurements. It also presents simple, inexpensive hardware and signal processing techniques for making the field measurements, and several new applications of electric field sensing. The signal

This paper shows how adaptive systems can learn to add an optimal amount of noise to some nonlinear feedback systems. Noise can improve the signal-to-noise ratio of many nonlinear dynamical systems. This "stochastic resonance" effect occurs in a wide range of physical and biological systems. The SR effect may also occur in engineering systems in signal processing, communications, and control. The noise energy can enhance the faint periodic signals or faint broadband signals that force the dynamical systems. Most SR studies assume full knowledge of a system's dynamics and its noise and signal structure. Fuzzy and other adaptive systems can learn to induce SR based only on samples from the process. These samples can tune a fuzzy system's if-then rules so that the fuzzy system approximates the dynamical system and its noise response. The paper derives the SR optimality conditions that any stochastic learning system should try to achieve. The adaptive system learns the SR effect as the sys...

In this paper, we address the problem of crosslayer denial of service in wireless data networks. We introduce SPREAD- a novel adaptive diversification approach to provide resiliency against such attacks. SPREAD relies on a mechanismhopping technique. Mechanism-hopping can be seen as a multilayer extension of the frequency-hopping technique for physicallayer protection against narrow-band jamming. In order to analyze the proposed approach, we propose a game-theoretic framework for analyzing the interaction of the communicating nodes and the adversaries and study the various possible strategies. We reason about the advantages of the proposed approach against various types of jammers. We demonstrate the effectiveness of our approach in the case of IEEE802.11 protocol stack by studying the EIFS attack, Packet-Size Game, and Coding-Packet-Size Game. As an example, we show that mechanism-hopping over two instances of IEEE802.11 can achieve a gain in throughput of several orders of magnitude over a single-instance network.

CDMA systems commonly use aperiodic spreading codes to distribute a signal spectrum uniformly over the channel bandwidth and differentiate neighboring cell sites. CDMA receivers often suffer from interference due to multipath fading. Blind signal estimation schemes cannot be used because they require periodic spreading sequences. RAKE receivers are often used, but they cannot fully exploit the rich structure of CDMA signals to minimize interference. This paper presents an iterative technique to estimate multipath parameters which can serve as a preprocessing step in a receiver to increase signal-to-interference ratio. We investigate the performance of the proposed method using computer simulations. Preliminary simulation results show an average of 10 dB gain on channel parameter estimation. 1

Abstract—This paper presents a novel robust watermarking approach called FuseMark based on the principles of image fusion for copy protection or robust tagging applications. We consider the problem of logo watermarking in still images and employ multiresolution data fusion principles for watermark embedding and extraction. A human visual system model based on contrast sensitivity is incorporated to hide a higher energy hidden logo in salient image components. Watermark extraction involves both characterization of attacks and logo estimation using a rake-like receiver. Statistical analysis demonstrates how our extraction approach can be used for watermark detection applications to decrease the problem of false negative detection without increasing the false positive detection rate. Simulation results verify theoretical observations and demonstrate the practical performance of FuseMark. Index Terms—Data fusion, digital watermarking, image tagging, logo watermarking, multimedia security.