Laurence B. Milstein - US grants

ABSTRACT EEC-9726413 KU This two year "TIE" project funds a collaborative study with two Industry/University Cooperative Research Centers (I/UCRC). The two I/UCRC's are the Rutgers University Industry/University Cooperative Research Center for Wireless Information Networks and the University of California San Diego Industry/University Cooperative Research Center for Ultra-High Speed Integrated Circuits and Systems. The "TIE" project is entitled, "Interference Cancellation Prototyping and ASIC Development for Wireless CDMA Communication." The Rutgers University I/UCRC will investigate the critical issues of acquisition and synchronizing essential for multi-user direct sequence CDMA communication convolution coding and utilize recent results on multi carrier DS/CDMA systems. In the second year, further research to study other multi-user detection architecture will be carried out after adding radio frequency hardware. The University of California - San Diego Center will work with the Rutgers University Center in designing an interference cancellation chip and give it to National Semiconductor Corporation for fabrication. In the second year, the chip will be tested and incorporated into a CDMA communication system for multi-users.

Although there have been enormous advances in communications over the past several decades, the vast majority of personal communications today is still done through wired systems. However, with the coming of age of personal communications networks (PCN) and digital cellular communication, more and more communications will be wireless, or untethered in the future. A major consideration in PCN is the multiple accessing technique, and it appears that spread spectrum code division multiple access (CDMA) is the best choice. This research deals with the CDMA environment, and a modified design of the standard receiver that results in enhanced system performance is presented. The redesign is based around the signal processing technique of transform domain processing and will result in a receiver which more closely approximates an optimal detector than does the conventional correlation receiver. The research will involve analysis an numerical simulation.

9419520 Ku The Industry/University Cooperative Research Center for Ultra High- Speed Integrated Circuits and Systems is a multi-site Center with the University of California, San Diego and San Diego State University. The Center research addresses critical issues in the design and fabrication of ultra high-speed circuits for communications and digital processing systems. The Center continues to meet the renewal criteria of the Industry/University Cooperative Research Centers Program. This award provides funding for one year to the University of California, San Diego under the "Self-Sufficient Partnership for Research" Program. Additional funding is provided by the U.S. Department of Navy (NCCOSC) to augment the Centers ongoing research program and to obtain a membership in the Center. The Program Manager recommends the University of California, San Diego be awarded $50,000 for one year. An additional $24,609 is recommended for one year with funds provided by the U.S. Department of Navy (NCCOSC).

9424109 Ku This award provides funding for an evaluator to study the industry/university interaction occurring in the University of California, San Diego's Industry/University Cooperative Research Center for Ultra-High Speed Integrated Circuits and Systems. The Center continues to meet the requirements for an Industry/University Cooperative Research Center. The study will document the interactions occurring between the industry and university researchers and will provide the data to the Program Data Bank maintained at North Carolina State University. The Program Manager recommends the University of California, San Diego be awarded $8,000 for the first year of a three-year continuing award.

Traditionally, in order to address the many complex issues that arise in communication networks, a ``layered" approach has been taken. The different layers are typically assigned different ``responsibilities," so that the general network design problem can be decomposed into simpler, more manageable problems. However, the independent design of the different layers - which ignores the detailed nature of their mutual interactions, shared constraints, and cumulative impact on the network's overall performance - can lead to inefficiencies. Future wireless communication networks will be required to provide wide coverage and high capacity to mobile users generating bursty multi-media information. This heterogeneous traffic will impose upon the network time-varying quality of service (QoS) constraints. Since many multi-media applications have delay-sensitive information with varying reliability requirements, such as numerical data, voice, and video, the project will take end-to-end delay and data integrity as its dominant system constraints. The goal of this project is, in the broadest sense, to take a more global view of end-to-end performance, to better understand the interactions among the layers, to develop techniques that improve system performance through joint optimization over the various layers and to do so in the context of a end-to-end delay constraint. One key theme of the proposal involves the optimization of system performance in the context of multiple users, particularly in a system which does not employ a cellular-type architecture. This requires the development of techniques that, on the one hand, address the deleterious effects of multiple-user interference at the physical layer, yet also incorporate end-to-end QoS objectives, especially delay, just as with the development of routing and scheduling algorithms. Another major theme will be the determination of the optimal distribution and the real-time dynamics of error control functions implemented across t he layers of the network, subject to specified end-user requirements. This requires investigation of inherent tradeoffs between error-rate and decoding delay of FEC employed at the physical layer, as well as the interactions among error control functions, including retransmission strategies, invoked at higher levels.

ABSTRACT EEC-9729254 KU Direct conversion receivers for wireless communication require less components and eliminate the need for bulky image rejection IF filters. This is joint "TIE" project linking the research capabilities of two Industry/University Cooperative Research Centers (I/UCRC) to study techniques for on-line adaptive digital compensation of the imperfections of analog components of mixed-mode transceiver circuits. The research site will be conducted at Oregon State University, the research site of the I/UCRC for Design of Analog Digital Integrated Circuits, and the University of California, San Diego I/UCRC for Ultra-High Speed Integrated

In this project, three researchers, and a team of graduate students, from
the University of California, San Diego (UCSD), shall undertake
theoretical and experimental investigations of data modulation schemes for
efficient information transmission in conjunction with CDMA encoded
ultrashort pulses in an optical fiber. Efficient modulation formats will
result in aggregate transmission rates exceeding one terabit/second, with
individual user rates on the order of 100-1000 megabit/second. The specific
objectives of this project include modeling of the CDMA, statistical
analysis of the transmitted waveforms, investigation of various CDMA codes
that support thousands of users with minimal interference, bit error rate
analysis of received signals for various modulation schemes, means to
provide QOS levels, modeling and characterization of the distortions
induced by the fiber channel, adaptive equalization techniques for reducing
fiber distortions, computer simulations of the modulation schemes, and
experimental evaluation of the modulation schemes, transmitter, optical
channel, and receiver. The goal of this proposal is to demonstrate a
prototype network with several users employing a modulation format which
when scaled up to the full number of users will carry over one terabit per
second of information.

The potential impact of the work will be in the proof that CDMA encoding of
ultrashort pulses is a realizable and desirable alternative to wavelength
division multiplexing (WDM).

In this proposal, three researchers from the University of California, San Diego (UCSD), specializing in the fields of optics, communications, and computer networks, are collaborating on the Ultra-High-Capacity Optical Communications and Networking initiative. It is felt by many researchers that the most efficient and economical way to utilize optical transmission technology for large scale networking is to use wavelength division multiplexing (WDM) in a circuit switched mode, overlaid with packet switching implemented with electronics. While this may indeed be the case, it is important to investigate alternative approaches that have great potential. The UCSD team has been investigating novel techniques of information transmission via optical fiber, where code division multiple access (CDMA) using ultrashort laser pulses is employed. Compact, low cost fiber-based ultrashort pulse sources are currently being developed, making the technology suitable for future practical networks. When an ultrashort pulse is encoded for CDMA, the pulse spreads out in time and resembles a noise burst that is transmitted on the optical fiber. At the receiving node, a decoder is applied to the received signals from multiple users, which matches only the encoding of the desired transmitter. The matching signal component is transformed back to an ultrashort pulse form that can be detected over the remaining interference from other users with nonlinear optical techniques. A novel high resolution pulse synthesis and detection technique for ultrashort pulses developed at UCSD enable various data transmission formats to be considered, such as ultrafast packet transmission with on/off keying, pulse position modulation, and amplitude modulation. The CDMA scheme enables large scale, asynchronous, concurrent access to the transmission resources. With a suitable architecture, this can be exploited to simplify network control, and increase reliability and flexibility.

The objective of this proposal is to conduct basic research by investigating theoretically and verifying
experimentally data modulation schemes for efficient information transmission in conjunction with CDMA encoded ultrashort pulses in an optical fiber network. Efficient modulation formats will result in aggregate transmission rates exceeding 10's of terabits/second, with individual user rates on the order of 1-10 gigabits/second. The specific objectives of this proposal include modeling of the optical CDMA for ultrashort Gaussian pulses, complete statistical analysis of the transmitted waveforms, investigation of various optical CDMA codes that support thousands of users with minimal interference, bit error rate analysis of received optical signals for various modulation schemes, modeling and characterization of the distortions induced by the fiber channel, adaptive equalization techniques for reducing dispersion and other fiber distortions, computer simulations of the modulation schemes, and experimental evaluation of the communication system: transmitter, optical channel, and receiver. The various phases of the proposed project complement each other. Combined together, they provide for in-depth knowledge of the theoretical and experimental issues of communicating with CDMA encoded ultrashort pulses. These findings will be shared with the scientific community, enhancing not only the knowledge base of other researchers in the field, but also of the students conducting the research. We shall demonstrate a prototype optical network with several users employing the modulation format that will carry over 10 terabits per second of information, when scaled up to the full number of users.

The potential impact of the work will be in the proof that optical CDMA encoding of ultrashort pulses is a
realizable and desirable alternative to WDM. Currently, WDM is the preferred multiplexing method due to its
simplicity and low cost. While WDM does increase the transmitted bandwidth significantly, it still does not fully utilize the available optical bandwidth due to both the need for guard bands between channels and the under utilization of channels. In contrast, CDMA encoded ultrashort pulses share the entire bandwidth without the need for guard bands, leading to efficient utilization of transmission resources. Using CDMA can also provide a highly flexible and robust infrastructure, upon which packet switching can be overlaid. The CDMA format also provides a degree of security, as no data can be extracted without knowledge of the codes employed.

To achieve more efficient spectrum utilization, the FCC has been revisiting traditional license-based policies and moving toward the increased use of unlicensed, rule-based, strategies. In this scenario, attention is being given to cognitive radio, which uses spectrum on an opportunistic basis.
The investigators study the design and performance evaluation of algorithms for the transmission of real-time video over cognitive radio channels. Since this technology involves sharing common spectrum, one key question is how much interference its deployment will impose upon the primary users' signals occupying the band. The investigation involves designing specific compression algorithms for video transmission over an opportunistically-used channel, and determining end-to-end performance in terms of video quality.

The goal of a cognitive radio is to increase the spectral efficiency of allocated spectral bands by opportunistically making use of spectrum that is temporarily free of traffic. This is accomplished by sensing the channel, and adapting parameters of the transmit waveform such as modulation format, power, bandwidth, frequency location, and code rate. This research takes a cross layer approach, involving physical layer waveform design, receiver design, and channel state information, and application layer considerations, such as scalable video coding, multiple frame prediction, and end-to-end distortion measures.
System components consume bandwidth and delay, and the research involves allocating a fixed bit budget and/or delay budget across layers. For example, a delay constraint necessitates tradeoffs between system components such as interleaver size and source encoder output buffer size. The main topics investigated are: (a) Adaptive receiver design and performance analysis for video transmission over cognitive radio mobile channels, (b) Optimal design of scalable video encoding for a cognitive radio environment, and (c) Optimal delay budget allocation.

Scalable Multimedia with Unequal Error Protection
Pamela C. Cosman Laurence B. Milstein
Abstract
In today?s communications environment, it is important to have rich media content (images, audio, video) that can scale up or down depending on availability of resources. In quality scalable multimedia, some portions of a bit stream contain information that allows a moderate quality reconstruction of the image or video, and additional portions of the bit stream allow the source to be reconstructed at progressively higher quality. We consider the transmission of scalable multimedia data (image and video) through variable types of channels, with a focus on providing different levels of unequal error protection (UEP) appropriate for different levels of information importance and suitable for the channel conditions.
There are many techniques for providing protection against errors, including forward error protection (FEC), hierarchical modulation, and leaky and partial prediction in video coding. Our research involves two new techniques for combining hierarchical modulation with either image or video to produce enhanced performance. We consider a MIMO-based technique, in which MIMO space-time coding is used to increase reliability for the most important information in the scalable image or video data, whereas MIMO spatial multiplexing is used to increase data rate for the less important information. This is combined and optimized with existing techniques where unequal error protection is achieved by transmitting different power levels on multiple antennas. The hierarchical approaches for UEP, as well as the MIMO techniques for UEP, are considered in conjunction with FEC and with leaky/partial prediction mechanisms for scalable video. We also consider UEP for cooperative communications, where a virtual MIMO array is formed out of cooperating nodes. Lastly, we investigate the effects of delay considerations in UEP.

The prominence of 3D video technology has skyrocketed. The 2009 movie Avatar in 3D became the highest grossing movie of all time. Such a movie requires left and right views of a scene. Many video games which provide a 3D experience require multiple views of a scene. Such data is costly to store and to transmit.

This research studies how to efficiently compress multiple-view video data, how to allow the scene to be viewed from any angle at different levels of precision, and how to reliably transmit the data over mobile wireless channels. This research has important applications in science education, traffic monitoring, and surveillance and security.
This research studies efficient encoding, rendering, and transmission of multi-view video, aiming for robust performance at arbitrary speeds of mobile units. The research is applicable both to videos of the real world taken with multiple cameras, and to rendered videos. The investigators study left/right view coding such as in the H.264 MVC standard, and view+depth coding. The latter approach is enhanced by encoding the error signal between the original view and its decoder-synthesized version. To optimally design the system, the techniques use cross-layer optimization, in which physical-layer channel-state information and application-layer distortion-rate or slice-priority information are exploited. Whenever multiple views are rendered from an underlying 3D virtual world, the application's bit requirements can be hugely altered by rendering parameters which affect the content and level of detail of the scene. The investigators study user-experience models to quantify the relationship between rendering parameters and user satisfaction, and develop a channel-aware adaptive encoding and rendering algorithm to account for fluctuations caused by transmission over a mobile channel.