Mohsen Kavehrad - US grants

9820604
Kavehrad

The need for high-speed portable multimedia workstations is expected to accelerate the use of broadband wireless local access. Portable radio head devices require low power consumption, small size and weight. The demand for inexpensive, high-speed transmission links satisfying these requirements has motivated the research on indoor wireless access. Future portable multimedia workstations need wide bandwidth connections to cabled backbone LANs in order to transfer high data rates in the order of 150 Mb/s or more in multimedia communications. There are major technological challenges for broadband wireless local access and this is an important research area. Both IR and Radio Frequency (RF) technologies are being examined for this application. However, indoor wireless IR offers a great number of advantages over indoor RF as will be explained in the next section.

The proposed research is focused on a novel design of a jointly optimized transceiver optical antenna diversity system for broadband wireless ATM indoor IR local access. To achieve this, we plan to work on a spot-diffusing multiple lines-of-sight approach through:

1. Design and fabrication of a computer generated holographic beam-splitter, to be used at the transmitter for producing multiple diffusing spots;

2. Design and fabrication of a holographic mirror combining, concentrating and filtering functions, to be used at the narrow field-of-view branches of a composite angle diversity receiver;

3. Joint optimization of transmitter and receiver parameters;

4. Prototyped models will serve as broadband wireless access means, interfacing an ATM local area network of high-speed multimedia work stations. We will also investigate whether Quality-of-Service (QoS) of an end-to-end ATM virtual connection can be guaranteed through such a wireless physical medium.

In comparison with any currently available wireless IR optical transmission system, the effort should result in a higher transmission rate of about OC-12 and a larger range of coverage of about 100 meters diameter. The wireless configuration will be capable of handling many-to-one and one-to-many communications without direct line-of-sight requirements and will be tolerant to shadowing and blockage.

This research aims to unite broadband communications with wireless access thus making possible un-tethered access to a wide range of broadband communications services, such as interactive multimedia communications, high resolution image or large file transfer, and high resolution video teleconferencing. This is done through millimeter wave radio technology and small high-gain antennas. This technology is termed next-generation local multi-point distribution system (NG-LMDS). This is intended to be a cost-effective competitor to all wire-line proposed alternative methods of broadband distribution. Broadband wireless access will afford potentially enormous bandwidth on demand to people. It has the potential to simplify access to interactive business, information and entertainment services by subscribers in fixed locations.

Establishment of a local wireless access network which integrates the most advanced millimeter-wave radio technology, coupled with asynchronous transfer mode Wireless Access Point (WAP) will provide homes, schools and businesses with the benefits of choice as regards the expanding list of broadcast and bi-directional multimedia communications services. The research structure involves:

Statistical analysis of interference in an ATM-LMDS cellular configuration.

Design of fixed-cellular ATM-LMDS architectures; with minimum interference by taking advantage of high-gain antennas, frequency-segmentation and polarization interleaving.

Analysis of spectral-efficiency in frequency reuse ATM-LMDS cellular architectures.

Extending the dynamic range of adaptive-coding by combining it with adaptive modulation in ATM-LMDS cellular architecture.

Investigating the influence of feedback channel impairments and transmission delay on the performance of adaptive rate systems in preserving an end-to-end Quality-of-Service in ATM-LMDS wireless loop.

Analysis of delay and throughput in ATM-LMDS fading channel, using adaptive rate coding techniques.

Assessing effects of adaptive transmission rate on the interference level of ATM-LMDS cellular architecture.

The objective of this research is to design wireless optical communication techniques for integration into sensor networks. The approach is to employ low-cost, compact-sized, and power-efficient white LEDs and photolithographic optical transceivers, in conjunction with indoor environment channel modeling and spatially coded multiple access techniques, to realize secure broadband communications interfaces among sensors.

The intellectual merit of this work lies in its potential to provide capacity and quality-of-service superior to conventional radio frequency techniques. This research directly addresses the challenges in obtaining parallel independent optical communications channels that will provide a means of spatial diversity, which, in turn, will result in improved power budget. Furthermore, use of photolithographic (thin film) beam splitters and combiners and white LEDs for transceiver optics pose a challenging, but promising, new area for sensor networks communications.

The broader impacts of this research include more efficient and more reliable communication links for facilities that rely upon sensors for collecting/distributing vital information (hospitals, planes, ships, factory plants). Co-existence with RF sensitive devices will make the proposed system robust and attractive for universal usage. Furthermore, this research will contribute to education by being incorporated into lectures on optics and wireless communications science and engineering, providing opportunities for undergraduate and graduate students to obtain multi-disciplinary hands-on experience on issues related to wireless optical communications system design and networking.

0968650 Pennsylvania State University; Mohsen Kavehrad
0968651 Tufts University; Valencia Joyner
0968662 University of California-Riverside; Zhengyuan Xu

The Center for Optical Wireless Applications (COWA) will focus on developing new devices using White Light Emitting Devices (WLEDs). Pennsylvania State University (PSU), Tufts University (TU) and the University of California-Riverside (UCR) are collaborating to establish the proposed center, with PSU as the lead institution.

The primary goals of this planning project are to initiate formal partnership with various industry partners and national laboratories that have an interest in optical wireless applications designs, and to discuss fundamental issues and topics for research. The main objective of the envisioned research projects at the proposed Center is to develop a new generation of environment-friendly extremely wideband optical wireless technology applications. The PIs' effort will involve work in relevant device designs, in optical wireless communication systems (physical layer), in networking, sensing, and in imaging.

The proposed Center has the potential to improve the profitability of US manufacturing by developing new optical wireless devices that will improve communication systems, reduce energy consumption and pollution. The proposed Center will offer a series of short courses to update the knowledge of the current workforce and will help universities to tailor new course offerings and to modify existing course offerings to better provide instruction for related areas and industry needs. The Center plans to promote diversity, building on all three universities' high ranking in education of minorities. In addition, the Center will work with existing university resources to recruit and build strong relationships with minority and women-owned companies and provide a collaborative community, within which these companies can contribute expertise, expand their networks and become more globally competitive.

I/UCRC for Optical Wireless Applications

1160924 Pennsylvania State University; Mohsen Kavehrad
1161010 Georgia Tech; Gee-Kung Chang

The Center for Optical Wireless Applications (COWA) will focus on generating technology that enables manufacturing of specific devices with larger communications capacity, employing integrated opto-electronics device design with interfaces necessary to facilitate collaborative device, system and network design. Pennsylvania State University (PSU) and Georgia Tech (GT) are collaborating to establish the proposed center, with PSU as the lead institution.

The objective of this proposal is to establish an NSF-sponsored Industry & University Cooperative Research Center on Optical Wireless Applications (COWA), in order to explore Optical Wireless Technology and economic potentials of energy efficient light sources through innovative designs and applications of solid-state optical sources and detectors for a wide range of practices that include optical imaging, remote sensing, communications and networking. The envisioned Center is based on the integration of interdisciplinary expertise at PSU, and GT with devices and systems-based engineering design and networking concepts.

The envisioned Center will include efforts to instill the cultural paradigm shift associated with promoting research programs of interest to both industry and universities; exploring and extending the interface between engineering systems design, networking and integrated electro-optic device designs; improving the intellectual capacity of the workforce through industrial participation and conduct of high-quality research projects; and developing curriculum in components, systems and networks design aspects of optical wireless applications. The results of this research are expected to contribute to the business competitiveness, energy security, environmental protection, and climate forecast. The proposed Center will make every effort to promote diversity. In addition, it will work with existing university resources to recruit and build strong relationships with minority and women-owned companies.

Abstract (Proposal No.1201636)

Intellectual Merit: The objective of this research is to demonstrate feasibility of using optical wireless communications and sensing technologies to implement very high data rate, self-configuring, low-complexity and low-power in-building multimedia networks, that will not require pointing, allowing the network to be robust and portable-friendly. The intellectual merit of this work is in the exploitation of the 10Gbps optical wireless transceivers along with fly-eye optical receivers for data-rate-intensive, immersive and interactive audio-visual applications for educational purposes, medical collaboration and corporate presentation functions, whereas current high-definition multimedia and video projection units that serve these purposes operate through wired connections to a computer or a portable. The project will primarily focus on faster and efficient modeling and categorization of a variety of indoor optical wireless propagation environments, optimization and design of optical transmitters and fly-eye receivers, and assessment of communications performance measures, such as bandwidth and error rate performance. The anticipated result of the research is a proof-of-concept optical wireless system for high-fidelity video transmission.

Broader Impacts: The broader impact of this research is transformative in several ways. Firstly, it will pave the way for broader commercialization of optical wireless communication products, and serve as a pioneer for other feasible optical wireless applications including wireless area networking. Secondly, it will prove the feasibility of a product capable of delivering high-quality multimedia-rich content to large classrooms and conference audiences. It is anticipated that the high bandwidth, portable-friendly optical wireless communication technology resulting from this research will leap-frog current technologies, providing domestic leadership in the development and manufacture of ultra-high bandwidth optical wireless network components. Thus the United States of America as a whole will see financial benefits in the form of exporting high tech products, training a more globally competitive workforce, and other industries will benefit through increased competitiveness by making early use of the new products. This new paradigm will be a breakthrough in high-speed wireless frontier. Furthermore, this research will contribute to education by being incorporated into lectures on optics and wireless communications engineering, providing opportunities for undergraduate and graduate students to obtain multi-disciplinary hands-on experience on issues related to wireless optical communications system design and networking.

Data centers are a critical piece of the infrastructure supporting our society. They flexibly supply the computing resources that enables the Internet-based economy. The design of a robust data center network fabric is challenging as it must satisfy several goals, viz., high performance, low equipment and management cost, incremental expandability to add new servers, and other practical concerns such as cabling complexity, and power and cooling costs. The project envisions and delivers on a datacenter network design approach that is radically different from prior architectures: a fully flexible, all-wireless fabric using Free-Space Optics (FSO) communication links, which essentially use laser beams to wirelessly transmit data through air. Although outdoor FSO links are challenging to operate under adverse weather conditions, their use in a temperature-controlled datacenter environments offers enormous and untapped potential in information-handling capacity. The proposed network design equips each rack of servers with a number of FSO devices, each of which can be "steered" in real-time to wirelessly communicate with another FSO device on a different rack. The steering ability enables a dynamic network that adapts to the prevailing network traffic. The project's success will have perceptible economic impact by making IT services more efficient - in terms of capital costs, operating expenses, and carbon footprint - across several critical sectors of the economy. The project will integrate the research with education to help students become domain experts in the datacenter networking industry, and actively encourage participation from under-represented minorities and women.

The project addresses a number of scientific challenges that arise in the context of the above proposed vision. (i) The project will develop cost-effective FSO devices that have a small form-factor and can be steered at fine-grained timescales. (ii) In addition, the project will develop viable mechanisms to facilitate clear line-of-sight for the FSO links, and address practical operational challenges (e.g., dust, vibrations). (iii) The project will explore algorithmic foundations for the design of flexible network topologies; (iv) The project will develop scalable network management solutions including algorithms to optimally select a runtime topology and route traffic; (v) mechanisms to guarantee desired properties (e.g., low congestion and latency) in a dynamically changing topology; (vi) Finally, the project will build a proof-of-concept system prototype and conduct extensive evaluation on appropriate platforms.