Cross-Layer Sensing, Estimation & Control in Wireless Networks

As mobile and machine-to-machine traffic is expected to grow exponentially in the next decade, tools for the design and optimization of agile and heterogeneous wireless networks are of great interest. Indeed, network design and operation have enormous complexity, due to the huge state space, the lack of global network state information at the decision units, the decentralized operation and resource constraints of wireless devices, thus requiring a holistic approach for network control and design. In this talk, I will present a principled framework for joint distributed sensing, estimation and control in wireless networks, which captures the interplay between state estimation and control and accounts for cross-layer factors such as the cost of acquisition of state information and the shared wireless channel.

The framework will be applied to a spectrum sensing-scheduling application, where a network of secondary users (SUs) attempts to opportunistically access portions of the spectrum left unused by a licensed network of primary users (PUs). Adaptive spectrum sensing and scheduling schemes are jointly optimized so as to maximize the SU throughput, subject to constraints on the PU throughput degradation and the sensing-transmission cost incurred by the SUs. I will show how low-complexity can be achieved by exploiting a large network approximation, a two-stage decomposition of the dynamic programming algorithm, as well as sparsity of network dynamics enabling efficient state estimation via sparse recovery techniques. Additionally, I will present a novel multiscale approach for spectrum sensing in large wireless networks, by which SUs maintain fine-grained estimates of the spectrum occupancy of nearby cells but coarse-grained estimates of that of distant cells. The cellular network is arranged into a hierarchy of increasingly coarse macrocells and SUs fuse local spectrum observations up the hierarchy. A probabilistic framework for spectrum sensing and information exchange is defined, which balances optimally improvements in spectrum estimation against energy costs.

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ECE Professor Larry Coldren receives The International Conference on Indium Phosphide & Related Materials (IPRM) Award

photo of larry coldren
Coldren receives the IPRM Award in recognition of his leading contributions to the development of InP-based semiconductor lasers and photonic integrated circuits for optical fiber communications

Professor Coldren received the award on June 30th at the 2015 Compound Semiconductor Week (June 28 – July 2) held at the University of California, Santa Barbara.

About the IPRM Award
The International Conference on Indium Phosphide and Related Materials (IPRM) has a long tradition of recognizing individuals who made significant contributions to the success of previous IPRM conferences through technical and/or organizational accomplishments by presenting the IPRM Award (formerly Michael Lunn Memorial Award). It is intended to continue this tradition also in 2015.

The nomination and selection procedures are taken care of by the International Steering Committee of IPRM. The 2015 award will be presented to the winner at the CSW ISCS/IPRM Award Ceremony.

About Professor Coldren
Larry A. Coldren is the Fred Kavli Professor of Optoelectronics and Sensors and holds appointments in Materials and Electrical & Computer Engineering. In addition, Coldren is a leading researcher with the Institute for Energy Efficiency’s Electronics and Photonics Solution Group. Coldren received his Ph.D. degree in Electrical Engineering from Stanford University in 1972. After 13 years in the research area at Bell Laboratories, he joined UC Santa Barbara in 1984 and is Director of the Optoelectronics Technology Center. In 1990 he co-founded Optical Concepts, later acquired as Gore Photonics, to develop novel VCSEL technology; and in 1998 he co-founded Agility Communications, later acquired by JDSU, to develop widely-tunable integrated optical transmitters. Coldren has authored or co-authored over a thousand papers, 8 book chapters, 2 textbooks, and has been issued 65 patents. He is a Fellow of the IEEE, OSA, and IEE, the recipient of the 2004 John Tyndall Award, the 2009 Aron Kressel Award, and a member of the National Academy of Engineering.

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Professor Chris Palmstrom named by the DoD as a National Security Science and Engineering Faculty Fellow (NSSEFF)

photo of chris palmstrom
ECE and Materials Professor Christopher Palmstrom selected in the topic area of functional materials for his project titled “Engineered Heusler Compound Heterostructures and Superlattices”

The Department of Defense (DoD) recently announced the selection of seven distinguished university faculty scientists and engineers forming the next new class of National Security Science and Engineering Faculty Fellows (NSSEFF). The NSSEFF program awards grants to top-tier researchers from U.S. universities to conduct long-term, unclassified, basic research of strategic importance to DoD. These grants engage the next generation of outstanding scientists and engineers in the most challenging technical issues facing the Department.

Up to $3 million of research support will be granted to each NSSEFF Fellow for up to five years. The fellows conduct basic research in core science and engineering disciplines that underpin future DoD technology development. This year’s topics included quantum information science, engineering biology, neuroscience, nanoscience, novel engineered materials, and applied mathematics and statistics. In addition to conducting this unclassified research, the NSSEFF Program includes opportunities for fellows to participate in the DoD research enterprise and share their knowledge and insight with DoD military and civilian leaders, researchers in DoD laboratories, and the national security science and engineering community.

The National Security Science and Engineering Faculty Fellowship (NSSEFF) program is sponsored by the Basic Research Office, Office of Assistant Secretary of Defense for Research and Engineering (ASD (R&E)). NSSEFF supports basic research that may lead to extraordinary outcomes such as: revolutionizing entire disciplines, creating entirely new fields, or disrupting accepted theories and perspectives. It is the Defense Department’s largest single-investigator program.

Professor Chris Palmstrom, one of the world’s leading researchers of electronic materials, joined the ECE faculty at UCSB in the Fall of ’07. Palmstrom received his PhD in Electrical and Electronic Engineering from the University of Leeds (England) in 1979. After five years of research on semiconductor materials and contact techonologies at Cornell, he joined Bellcore in 1985. There, he did groundbreaking research on semiconductor surfaces, semiconductor doping, polymer/polymer diffusion and the molecular beam epitaxial growth of metal/semiconductor heterostructures. In 1994, Dr.Palmstrom went to the University of Minnesota, where he soon became a leading researcher in several fields, including new spintronic materials that combine the functions of electronic and magnetic manipulation and storage on information.

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GRIT Talk — ‘RF and Robotics: Opportunities and Challenges’

photo of yasamin mostofi
These days, radio waves such as WiFi signals are everywhere. Can we use them for sensing? In this talk, I will discuss our latest results along this line. First, I focus on achieving x-ray vision with only WiFi signals, showing that it is possible to image details through thick concrete walls with only WiFi. Next, I focus on occupancy estimation where I show how to extract the level of occupancy from WiFi measurements. With the vision of unmanned vehicles becoming part of our everyday society soon, the talk also shows how WiFi signals can give x-ray vision to robots.

FREE and OPEN to the public | Refreshments Provided

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ECE Professor Umesh Mishra’s Gallium-nitride technology and startup Transphorm featured in The Wall Street Journal

photo of Umesh Mishra

“Energy-Saving Material Gets a Boost” (WSJ) — KKR leads funding round with $70 million to Transphorm, a startup developing an alternative to silicon

Gallium-nitride (GaN) a material used to make power-saving light bulbs is gaining momentum in the world of semiconductors. KKR & Co. is the latest to place a bet. “This is a multibillion-dollar market,” said David Kerko, a senior adviser to KKR. “This technology has extremely broad applicability.”

Umesh Mishra, Transphorm’s chairman and co-founder, estimates that 10% of all power used in the U.S. stems from losses during power conversion in electric motors and other products. Shifting entirely to gallium-nitride technology could save $20 billion annually in the country, his company estimates.

Transphorm is developing electronic components using gallium nitride rather than silicon, hoping to save energy in products that include solar panels, electric motors and power supplies for server systems. Other large and small companies are also developing semiconductors based on the material, which is used to make light-emitting diodes for light bulbs that consume less power and last longer than conventional bulbs.

The effort to take advantage of GaN is partly a response to technical and economic factors that have slowed improvements in silicon-based chips. While companies are still finding ways to fabricate smaller transistors in silicon, reductions in cost and power consumption have been more difficult to achieve.

Gallium-nitride technology is at a much earlier stage of development. Where some conventional chips now have billions of tiny transistors, companies such as Transphorm are fabricating individual transistors.

GaN circuits can switch on and off much more quickly than silicon and handle higher voltages, said Alex Lidow, Efficient Power Conversion’s chief executive — another startup using GaN. That makes the material particularly good for chores that involve power conversion, such as shifting from alternating to direct current or from high to low voltage.

Dr. Mishra doubles as a professor at the University of California at Santa Barbara, a longtime center for gallium-nitride research. His colleagues there include Shuji Nakamura, who won the 2014 Nobel Prize in physics for his work in perfecting the use of the material in lighting.

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ECE Assistant Professor Katie Byl and lab featured in The UCSB Current article about the DARPA Robotics Challenge (DRC) and their entry “Robosimian”

robosimian in action and team photo
UCSB and Caltech/JPL’s RoboSimian takes a top spot at the recent DARPA Robotics Challenge Finals

Drive up, get out of the car, make your way to the front door, open said door, step inside. We humans have performed this sequence of maneuvers countless times: going to work in the morning, coming home after a night of partying, in various kinds of weather and locations and at different hours of the day. For the most part, it’s effortless and unconscious.

But, that same set of movements is a huge challenge for robots, as UC Santa Barbara professor Katie Byl and her robotics team can attest. RoboSimian, a collaboration between Byl’s team and researchers from the California Institute of Technology and NASA’s Jet Propulsion Laboratory at Caltech, completed the Defense Advanced Research Projects Agency’s (DARPA) Robotics Challenge Finals in early June and came in fifth out of about two dozen teams from across the country and around the globe.

“I’m really happy with how we did,” said Byl, professor of electrical and computer engineering and of mechanical engineering at UCSB. “JPL designed and built RoboSimian, and my students — Brian Satzinger and Chelsea Lau — and I at UCSB have been helping JPL to write the software to control how the robot moves for the DARPA Robotics Challenge.” The DARPA contest’s overarching theme was to have competitors produce a robot that could eventually handle unpredictable terrain and manipulate tools for use in conditions inhospitable to humans. Think Fukushima nuclear plant meltdown or other disaster-response situations.

But first, the competitors had to figure out how to get their robots — many of them upright and bipedal — to drive the car proficiently, get out of the vehicle without losing balance and travel to the door and open it without keeling over. Proprioception, the ability of humans and animals to sense their positions relative to the environment and adjust their bodies’ reactions and movements to maintain balance under varying conditions, still has some way to go before it can be replicated in machines.

However, RoboSimian is ahead of the curve. It was one of only two robots (the other one is called CHIMP) that didn’t require human intervention to reset during either day of competition. The most common failure mode for other robots was falling down.

“RoboSimian has a phenomenal track record,” said Byl, whose research focuses on robot agility, reliability and response in variable conditions. “It’s fallen down maybe once in the past year of testing.” Even the creators of the winning robot, a humanoid designed by the Korea Advanced Institute of Science and Technology, had to take advantage of the grace period built into the competition that allows the robots’ handlers to reset their machines on the first day of testing, said Byl.

Videos selected Byl and her comments:

More information:

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Seniors Saili Raje (CE), Alexander So (ECE) and Shuan Chen (CE) honored at the 2015 College of Engineering “Senior Send-Off”

photo of alexander m. so and hsuan chen
College of Engineering (CoE) celebrates the undergraduate class of 2015 on June 12th at their annual “Senior Send-Off” event

The event program and reception included honoring seniors, teaching assistants and faculty members. The following Electrical & Computer Engineering (ECE) and Computer Engineering (CE) seniors received recognition:

  • Hynes/Wood Award — presented annually by the Engineering Student Council in recognition of outstanding contributions to student activities
    • Saili Raje (CE)
  • Outstanding Seniors (major highest GPA)
    • Alexander M. So (ECE) and Hsuan Chen (CE)
  • College of Engineering Honors Program Academic Excellence
    • ECE — Jason Farkas
    • CE — Hsuan Chen, Joel Dick, Metehan Ozten, Jocelyn Ramirez, Jonathan Simozar, Duncan Sommer, Eric Taba, and Oliver Townsend
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Nanostructured InP Based Materials and Their Applications in Classical and Quantum Optical Communication Systems

The talk will give a brief overview about the activities of our group at INA with a main focus on epitaxial growth of III-V quantum dot (QD) materials on InP using molecular beam epitaxy and in the realization of advanced optoelectronic devices based on nanostructured InP-based materials for classical optical communication systems (from long reach to on-chip) as well as for future quantum communication networks. In addition, an outlook will be given for a new optically active Si-based material for a next generation Si photonics platform.

Nanostructured optical gain materials have many advantages compared to the standard bulk or quantum film materials typically used in optoelectronics, e.g., much higher material gain, much faster intrinsic carrier dynamics, etc., with direct consequences for device properties, like low laser threshold current, higher temperature stability, reduced linewidth or multi-wavelength amplification. However, for many years QD materials suffered by an insufficient modal gain due to too large size inhomogeneity and too low QD density.

A few years ago new growth techniques for the growth on 1.55 μm QDs on InP material basis were developed, which tripled the modal gain of QD lasers and which can now fully compete in basic properties with quantum well lasers. Record values in digital modulation speed of 22 GBit/s could be obtained with 275 μm long 1.55 μm QD lasers. Similar QD material can be used to realize widely-tunable narrow-linewidth DFB lasers for coherent communication. Results will be shown giving a clear evidence for a strong linewidth reduction related to the quasi zero-dimensional character of the laser material.

For reducing power consumption in high-capacitance data networks all optical high-speed switching fabrics would be favorable to avoid high power consuming electro-optical conversions. Recent results on low-power (60 fJ/Bit) high-speed (6.5 ps) all-optical switches based on strongly coupled nanocavities and realized in InP photonic crystal membrane structures will be presented.
To establish future optical quantum networks on the basis of existing fiber networks, one of the key components are single or entangled photon sources emitting at 1.5 μm. For this purpose low-density quantum dot material on InP substrates were developed, with highly efficient narrow linewidth single photon emission.

A long ongoing dream in silicon based microelectronics and more recent nanophotonics is the integration of high-quality optically active components, like light sources, amplifiers and non-linear devices on Si chips. A lot of effort is focused on wafer fusion/bonding or flip-chip mounting techniques or on direct planar growth using thick relaxation layers. Unfortunately, none of these techniques are fully CMOS compatible and need separate III-V material processing.

Based on the recent progress to realize core-shell InAs/GaAs QDs with high optical quality directly grown on silicon surfaces, a radically new approach will be discussed for the realization of optically active silicon, which may allow the direct integration of III-V material in planar defect-free single crystal silicon matrix, and which can directly be processed with silicon technology.

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Lee (ECE) and Johnson (CE) receive “Outstanding Faculty” honors at the 2015 College of Engineering “Senior Send-Off”

photos of hua lee and john johnson

College of Engineering (CoE) celebrates the undergraduate class of 2015 on June 12th at their annual “Senior Send-Off” event

The event program and reception included honoring seniors, teaching assistants and faculty members.

The following Electrical & Computer Engineering (ECE) and Computer Engineering (CE) faculty received “Outstanding Faculty” recognition by the graduating seniors in their program:

  • Hua Lee (ECE) — instructs Circuits, Devices, & Systems (ECE 2A) and Signal Analysis & Processing (ECE 130B)
  • John Johnson (CE) — instructs Senior Computer Systems Project (ECE 189A/B) and Sensor & Peripheral Interface Design (ECE 153B)
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Bluestone and Zakhary receive “Outstanding Teaching Assistant” honors at the 2015 College of Engineering “Senior Send-Off”

photos of bluestone and zakhary
College of Engineering (CoE) celebrates the undergraduate class of 2015 on June 12th at their annual “Senior Send-Off” event

The event program and reception included honoring seniors, teaching assistants and faculty members.

The following graduate students received “Outstanding Teaching Assistant (TA)” recognitions from the graduating seniors in their program:

  • Aaron Bluestone — Electrical & Computer Engineering (ECE)
  • Victor Zakhary — Computer Engineering (CE)
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