Organizationally, STAR Lab is a research group within the
Department
of Electrical Engineering of Stanford
University. The Laboratory is composed of eight regular faculty,
a number of emeritus faculty with active research programs, three
consulting professors, several research associates, and more than
sixty graduate students and staff.
Research areas in the STAR Lab include electromagnetics and remote
sensing, communications, and signal processing.
Electromagnetics and Remote Sensing
Research in electromagnetics and remote sensing offers a variety
of means for learning about the natural environment. Measurements
using radio signals traveling between the ground and NASA planetary
spacecraft are used to study planetary atmospheres, ionospheres
(the ionized gases that surround planets), surfaces, and ring
systems, resulting in an important, precise source of information
on these objects. The geophysical properties of planetary surfaces
are inferred from carom signals traveling between orbiting spacecraft
and the earth via the surfaces of the planets. Professors and
students are active in many of NASA's
current planetary missions. The experimental program motivates
and is supported by ongoing theoretical work in advanced theories
of wave propagation and scattering. These theoretical and experimental
programs are supported by active research in the area of signal
processing and efficient techniques in using digital processors.
In recent years, the Ultra
Low Power Group has developed technology that allows processors
to operate 100 to 1000 times more efficiently than standard CMOS.
Work is being done at the algorithm, architecture, circuit, device,
and VLSI processing levels to achieve these high efficiencies.
As an example, the group recently produced the world's most energy-efficient
1024-point FFT processor.
Members of the laboratory are also engaged in
very low frequency research
into the origin and properties of electromagnetic signals in
the Earth's environment, their interactions with the energetic particles
in the earth's radiation belts, their effects on the ionosphere, and
their relation to other phenomena on and below the Earth's surface, in
the upper atmosphere, and in interplanetary space. Of particular recent
interest is the investigation of lightning discharges and their effects
on the earth's near space environment. Both natural and man-made
signals are studied in this research. Measurements are taken at a number
of locations around the wor
ld, including Alaska, Greenland and the
Antarctic.
Measurements in the Ultra Low Frequency
(ULF) range have recently led to the discovery that major
earthquakes may be preceded by low-frequency electromagnetic signals.
As a result, additional measurement systems are being built and
installed along the San Andreas fault in California. This research
has become a cooperative effort with the School
of Earth Sciences.
Research, pioneered at Stanford, is also ongoing in the further development
of radar remote sensing of ocean waves and current systems. Cooperative
research in this area is underway with faculty members in the
School of Earth Sciences.
STAR Lab maintains a variety of experimental research laboratories equipped
with state-of-the-art test and measurement equipment including
systems and workstations for use in signal and data analysis.
Several of these machines are equipped with graphics capabilities
as well as software tools for system and VLSI hardware design.
Wireless
Wireless technology has enormous potential to change the way people and
things communicate. Future wireless networks will allow people on the
move to communicate with anyone, anywhere, at any time, using a range
of multimedia services. Wireless communications will also enable a new
class of intelligent home electronics that can interact with each other
and with the Internet. A wireless communications infrastructure is also
needed for automated highways and for sensor networks, and wireless
video will support applications such as distance learning and remote
medicine. There are many technical challenges that must be met in order
to make this vision a reality. These challenges transcend all levels of
the overall system design, including hardware, communication link
design, and networking. In addition, synergies between the hardware,
link, and network designs must be exploited in order to meet the
demanding performance requirements of these future systems. STAR Lab
faculty are actively pursuing research in these areas, with specific
focus on capacity limits of wireless systems and networks, protocol
design and analysis for wireless cellular systems and ad hoc networks,
sensor network design, wireless communications for distributed control,
energy-constrained communications, and dynamic resource allocation in
wireless systems.
Broadband Access
STAR Lab faculty also research the infrastructure and supporting
methods to bring broadband access, typically 100 Mb/s, to all
users of the internet, residential or commercial. Such high-speed
connectivity may occur over wireline optical or copper links or
via wireless links, or more likely combinations of all three.
Such speed mandates deep investigation and understanding of the
fundamental limits of communications networks and transmission
media. Topics such as modulation, coding, information theory,
signal processing, networking theory, multiple antennas, and other
forms of diversity, are mainstream interests within the STAR Lab
faculty who address the broadband access area.
DSL
Professor Cioffi's group has one specific focus on high speed
transmission on copper twisted pair, with focus on modem technologies
for single or multiple users. This area is known as digital subscriber
lines. The current work investigates methods and bounds for multiple
users within a binder of crosstalking telephone lines, which is
one of the most challenging and difficult transmission problems
ever studied by information theorists and communication theorists.
Typically projects span the range of creating new information-theoretic
bounds for multiple-users of a communication system to design
and analysis of functional models for very high-speed transmission.
The group has worked with many companies to demonstrate 100 Mb/s
and higher-speed transmission over 100's of meters of single-twisted-pair.
Optical Communications
Optical communications is a fascinating, interdisciplinary field that
lies at the intersection of classical optics, quantum electronics, high-speed
circuits and communication theory. It is no surprise that this field
has attracted some of the greatest scientists and engineers of this
generation. The current Internet owes its existence to optical communications,
and the future growth of communication at all scales will depend increasingly
on advances in optical techniques.
While wide- and metropolitan-area networks have achieved terabit-per-second capacities, much work remains to further increase capacity and make these networks more flexible and robust. Perhaps the grand challenge of the next decade lies in providing economical access at high speeds (100 Mb/s) to every home, business and classroom. In local-area networks, new approaches are required to scale Ethernet speeds to 10 Gb/s and then 100 Gb/s. At a still smaller scale, optical communications is being used to overcome interconnection bottlenecks in computer backplanes and even at the chip scale.
Optical communication research in STAR Lab spans a wide range of disciplines,
including basic physics, optical devices, digital and analog communication
techniques, and networks. Optical media being studied include
single-mode fiber, multi-mode fiber and free-space links.
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