John R. Wullert

Challenges: environmental design for pervasive computing systems

We argue that pervasive computing offers not only tremendous opportunities and exciting research challenges but also possible negative environmental impacts, particularly in terms of physical waste and energy consumption. These environmental impacts will come under increasing government and consumer scrutiny, and like other disciplines (e.g. architecture, transportation), pervasive computing will have to adapt accordingly. Further, we argue that software-related issues will play an increasing role in reducing the environmental impact of computing. We thus propose that an important challenge for pervasive computing is to develop research in new architectures, design methodologies, metrics, algorithms and operating systems to minimize these impacts. We then discuss specific research issues and questions that arise in three phases of the device lifecycle: minimizing resource usage for manufacture and operation, maximizing device lifetime, and improving recyclability.

Holographic implementation of a learning machine based on a multicategory perceptron algorithm

An optical learning machine that has multicategory classification capability is demonstrated. The system exactly implements the single-layer perceptron algorithm and is fully parallel and analog. Experimental results on the learning by examples obtained from the system are described.

Compact and Ultrafast Holographic Memory Using a Surface-Emitting Microlaser Diode Array

A compact and ultrafast holographic memory using a recently developed surface-emitting microlaser diode array is described. The system does not require a bulky laser, spatial light modulators, or beam deflectors. The memory is capable of retrieving a high-resolution page (approximately 105 bits) in less than 1 nsec.

Generation of programmable coherent source arrays using spatial light modulators.

We demonstrate and characterize arrays of coherent focused spots generated by writing multiple Fresnel zone plates on optically and electrically addressed modulators. The programmable parameters of the array are its size (number of generated spots) and the transmissivity and focal length of each lens. As expected, phase modulators have a better conversion efficiency than amplitude modulators do.

Compact and robust incoherent holographic correlator using a surface-emitting laser-diode array

A compact and robust holographic correlator using a vertical-cavity surface-emitting microlaser diode array is described. The system is based on the unique coherence property of the surface-emitting microlaser array: temporally highly coherent and spatially incoherent. The performance of the system is experimentally demonstrated, and the application of the system for neural network implementations is proposed.

The Mobile Application Server (MAS): An Infrastructure Platform for Mobile Wireless Services

There has been a surge of interest in developing advanced mobile voice and data services. One of the biggest challenges faced by service providers is to create new services efficiently and rapidly. We describe the motivation, architecture and design of the Mobile Application Server (MAS), a Java middleware prototype platform for mobile services which provides basic common building blocks required by mobile wireless applications, such as user profile management, location handling, device detection, content adaptation and e-wallet functions. The MAS is modular, flexible, and provides an open API for 3rd party service creation. Users can thus utilize a variety of access technologies (CDPD, cellular, 802.11, SMS, etc.) and delivery mechanisms (HTML, WML, VoiceXML, etc.) while application developers are spared the details of this heterogeneity. The MAS also interfaces to traditional telecommunications system (A/IN) elements such as SCPs as well as Next Generation Network (NGN) or converged-network elements such as Call Agents. We present application examples of the use of MAS, initial performance measurements and discuss some lessons learned from this experimental system. We conclude with directions for further work.

Presence management in next-generation networks

The popularity of instant messaging highlights the power that the addition of presence information can bring to communications. Instant messaging systems combine multi-party communications with active presence notifications, allowing users to monitor the presence status of others. We describe several ways presence information can enhance next generation telephone communications and how integration can actually improve instant messaging as well. In addition, we will describe some of the issues associated with implementing and deploying such services, including privacy, data ambiguity and inter-system compatibility.

Analysis of storage requirements for video-on-demand servers

The choice of a storage technology for video-on-demand servers depends on a variety of factors. The primary technical factor is the number of video streams that the technologies can provide, while the initial cost of the memory technologies will play a major role in the final system price. This article compares various storage technologies and storage architectures for video-on-demand servers and analyzes the relative costs and performance of each. >

Holographic On-Line Learning Machine for Multicategory Classification

A holographic on-line learning machine that is capable of multicategory classification is described. The system exactly implements the single-layer perceptron algorithm in a fully parallel and analog fashion. The performance of the adaptive network is successfully tested for up to 24 characters with different scale and rotation. Also, a compact and robust version of the holographic learning machine is proposed.

VanderLugt correlator and neural networks

Several experimental demonstrations of neural networks using coherent optics are demonstrated. An associative memory for word-break recognition and a learning machine for multicategory classification are discussed. Finally, a compact and robust coherent optical processor using a recently developed SELDA (surface emitting micro-laser diode array) is described. Although the applications are different, all these implementations are based on the VanderLugt correlator.<<ETX>>