Broadband Access Networks
Systems
Our efforts in this area center around solving the
broadband access problems, e.g., those associated with hybrid - fiber /
twisted-pair / coax / wireless networks evolution. These networks are planned
to be transparent on the optical side, so far as advancements on the backbone
network are concerned. A major thrust will be our examination of possible
synergy between wired access platforms and wireless technologies.
Return
to CICTR Research Areas
Transmitting 40/100Gbps Data Rates over Category 7A Copper Cable
A recent collaboration between Nexans and
The
project focuses on assessment and design of transmission systems for
distribution of digital signals over standard Category-7A copper cables at
speeds beyond 10Gbps. The main focus is on the technical feasibility and system
design for data rates of 40 and 100Gbps over copper. Based on capacity analysis
and rate optimization algorithms, system parameters are obtained and the design
implementation trade-offs are examined. The simulation results confirm that
with the aid of Decision-Feedback Equalizer and powerful coding techniques,
e.g.
The results confirm the technical feasibility of
beyond 10Gbps high-speed transmission over standard Category 7A copper wire.
The assessment has revealed that
Click here to read the
paper: 40/100 Gbps Transmission Over Copper: Myths and Realities
Penn-State Research
News: Researchers
Push Transmission Rate of Copper Cable
November 2007 Plenary
Week IEEE 802.3 Higher
Speed Study Group Meeting,
News Media :
ZD-Net: 100 gigabits per second over copper?
Network
World: Researchers
pushing 100 Gig
United
Press International: Copper
cable transmission rate increased
____________________________________________
Wi-MAX Access Systems
IEEE
802.16e, the standard for Mobile WiMAX, is expected
to be published by the end of 2005 and the Mobile WiMAX
will be launching its service in
Since
IEEE 802.16e, the mobile version of IEEE 802.16-2004, will be published soon,
the focus of 802.16 is expected to be changed from fixed subscribers to mobile
subscribers with various form factors;
Unlike
the wired networks, wireless networks are highly dependent on communications channels;
radio channels are dynamic, correlated, unreliable and very expensive. This is
why the performance will be highly dependent on how well the radio resource
management supports QoS requirements even if QoS might be luxurious in early stages of the Mobile WiMAX market. Therefore, several cross layer issues in
In multi-user environments,
especially in wireless fading channels, multi-user diversity in radio resource
management is one of key elements in maximizing the throughput. Multi-user
diversity is a form of selection diversity. Since different users experience
independent time-varying fading channels in wireless networks, resources shall
be allocated to the user that has the best channel quality in order to maximize
the system throughput. Multi-user diversity drew attention since tracking the
channel fluctuations of the users is getting more accurate and faster. Hence,
the diversity gain increases when dynamic range of the fluctuation increases
but, the gain is limited in environments with slow fading. In slow fading,
multi-user diversity hardly satisfies all QoS
parameters at the same time, especially the fairness among all different users.
Ultimately, radio resource management need to implement a combined form of
multi-user diversity and fairness scheduler.
The architecture requires development of critical
components for the transceiver and systems. This includes providing
cost-effective distribution and coverage to subscribers, utilization of
low-cost monolithic IC and antenna technology, and implementing effective
transceiver linearity, modulation and coding and
Related
issues are being investigated:
·
BECHTEL Telecommunications Journal:
§
Jungnam Yun, M. Kavehrad,
“PHY/MAC
Cross-Layer Issues in Mobile WiMax,” Bechtel
Telecomm Technical Journal, Vol. 4, No. 1, January 2006.
- Alexander Lackpour,
M. Kavehrad and Scott Thompson,
“Architecture and Predicted Performance of an IEEE 802.11b-like
WMAN Transceiver at 5.8GHz,” Proceedings of the Third IEEE Workshop on Wireless Local Area Networks, Boston-Mass., September 2001. PRESENTATION .
- Opportunistic Communications – Adaptive-Rate
Techniques, Dynamic Network Resource Management
- Multi-Input-Multi-Output (MIMO) Systems; (see, e.g., Broadband Wireless Local Area Networks )
- Cellular Network Systems; Dynamic TDD:
·
Penn-State
Research News:
New
Allocation Technique Boosts Efficiency for Wireless Internet Access
·
The
·
ASME:
Clarifying
Wireless High-Speed Internet
·
Innovation
Reports: Allocation
technique boosts efficiency, minimizes interference for wireless internet
broadband
- Quality-of-Service (QoS) Metrics
- RF Propagation Modeling and Channel Characterizations.
Broadband Transmission over Power
Lines
A Solution to the Global Digital Divide Problem:
The medium-voltage (MV) power grid, typically
carrying Megawatts of power at 11,000 V, reaches within a few hundred meters of
most inhabited places on earth. The same grid is an excellent communications
medium, offering bandwidths well beyond 100MHz and potentially more, with
The power distribution grid resembles an omnipresent, widely
branched hierarchical structure. The structure of the medium (MV) and
low-voltage (
Many service providers are interested in introducing the next
generation broadband access to residential homes and small home offices (SOHOs) via power-line distribution network architecture,
termed Broadband over Power-Line (BoPL) transmission
network, in the not too distant future. A typical scenario for such an access
network is shown in Figure-1. In search of a proper end-to-end feasibility test
of the anticipated physical-layer design, we are conducting investigations on a
system level model. The work presents conceptual designs, analyses, computer
simulations and some experiments on a BoPL
transmission configuration to assess the potential interference problems.
Fig.-1 Power-Line
Broadband Access Network Architecture
Despite the enormous potential, there is some skepticism
about the technology and its commercial viability. This is due to several
technical problems and regulatory issues that as yet remain to be
resolved. Some of these issues are
listed below:
·
Power
line channel is harsh due to discontinuities (impedance mismatch), ground
effects, interference and noise, thus difficult to model.
·
Regulatory
issues naturally arise due to unshielded nature of overhead power lines, which
are both the source and target of electromagnetic interference.
·
Since
communication over power networks is basically wire-borne, suitable measures
have to be developed to prevent inadmissibly high signal radiations, i.e.,
interference to and from other services needs to be remedied.
In a
relatively complex grid of nodes and lines, discontinuities caused by Impedance
Mismatch between a node (e.g. a transformer) and a wire line connected to the
node, create reflections. These reflections give rise to a frequency selective
multi-path. There is also possibility of resonance effect, due to standing wave
formation, on transfer (magnitude and phase versus frequency) responses of an
end-to-end line between points A and B on the overhead MV power line grid, as
shown in example below [1]:
![Text Box: Transfer function between grid nodes A and B of the network in
Fig.-5 of [1] with discontinuity at nodes](index_files/image018.gif)
![Text Box: Impulse response for the path between A and B in Fig.-5
Of [1]](index_files/image019.gif)
The
impairments of Power-line Systems are similar to those of
We need to remember that
overhead MV power-lines are exposed. The use of electric power network to carry
RF waves is not unconstrained, because by occupying a frequency band of about
500 KHz to nearly 100 MHz, a frequency overlap is created with some existing
practices such as; the entire HF band services, long, medium, and short-wave
radios and amateur radio bands, as air-borne power lines also act as antennas,
transmitting and receiving interference to and from the surrounding
environments.
On April 27, 2004
·
Power control
·
Avoidance of locally used frequencies
·
Differential-mode signal injection
·
Filters and signal terminations to alleviate impedance mismatch
discontinuities
The
http://www.ntia.doc.gov/ntiahome/fccfilings/2004/bpl.
In June 2004, the White House called for the establishment of
technical standards to make possible new broadband technologies such as the use
of high-speed communications directly over power lines.
Meanwhile, in order for this technology to
be viable, some problems have to be solved, such as finding a suitable model
for the power line channel that incorporates signal degradation through the
line and by interference and noise sources, determining appropriate frequency
allocation schemes and acceptable transmission power levels to minimize
interference into existing services, and finally; selecting suitable transmission
schemes and countermeasures to effectively minimize the external interference
effects on the proposed system. It is important to remember that in
[1]
P. Amirshahi and M. Kavehrad,
“High-Frequency Characteristics of
Overhead Multi-conductor Power Lines for Broadband Communications,”
IEEE Journal on Selected Areas in Communications, Vol. 24, No. 7, July 2006.
[2]
P. Amirshahi and M. Kavehrad,
“Transmission
Channel Model and Capacity of Overhead Multi-conductor Medium-Voltage
Power-lines for Broadband Communications,” IEEE Consumer
Communications & Networking Conference,
[3]
P. Amirshahi and M. Kavehrad,
“Medium
Voltage Overhead Power-line Broadband Communications; Transmission Capacity and
Electromagnetic Interference,” Proceedings of ISPLC 2005,
[4]
Paul
S. Henry, “Interference
Characteristics of Broadband Power Line Communication Systems Using Aerial
Medium Voltage Wires,” IEEE
Communications Magazine, pp. 92-98, April 2005.
[5]
P. Amirshahi and M. Kavehrad,
“System Design Considerations for High data
Rate Communications Over Multi-wire Overhead Power-lines,” The
VI IEEE International Workshop on Signal Processing Advances in Wireless
Communications,
[6]
P. Amirshahi, S.M. Navidpour and M. Kavehrad, “'Fountain Codes for Impulsive Noise Correction in Low-Voltage Indoor Power-line Broadband
Communications,” IEEE Consumer Communications & Networking
Conference, Las Vegas, Nevada, January 2006.
[7]
P. Amirshahi and M. Kavehrad,
“Broadband Access over Medium and Low Voltage Powerlines and use
of White Light Emitting Diodes for Indoor Communications,” IEEE Consumer
Communications & Networking Conference,
[8]
Amy
K. Glasmeier, Chris Benner, and Chandrani
Ohdedar, “BEYOND THE DIGITAL DIVIDE:
Broadband Internet Use and Rural Development in Pennsylvania,” Final
Report to the Center for Rural
See also:
·
Scientific American: Broadband to the people
·
NetworkWorld: A
two-pin plug and you have broadband
·
The Energy Daily:
Repeaters are Key
·
Solution to the Global Digital Divide Problem
·
Black Issues in Higher Education: Penn State Engineers
Present Expanded View of Broadband by Power Lines
·
Penn-State Research News: Power Line Data
Transmission Capacity: Bigger Than DSL Or Cable
·
CICTR News: http://cictr.ee.psu.edu/cictrnews.htm
·
FCC Chairman
Powell kicks off his new regular AO blog:
Michael
Powell Joins the Blogosphere
·
·
Electronic Clipping: Alliance opts for interoperable powerline broadband specs
TV
Interview:
Click
on the line below to see and hear the interview:
High-voltage electrical power lines
could be used for communications
Acknowledgments
This research is supported by the
AT&T Shannon Labs through a grant and by the CICTR of The Pennsylvania
State University.
Hybrid Wireless Access
Systems
The allocated bandwidth for RF FWA is adequate for both point-to-point
high capacity trunk lines and point-to-multipoint shared bandwidth last miles
connections. Furthermore, if broadband Wireless Optical links or Hybrid Optical & RF
Combined Wireless Links are used, there
is a huge and as yet unregulated optical spectrum available which is secure and
easily reusable, due to availability of focused optical beams.
Atmospheric-optical-wireless links are excellent means for extending the fiber
reach into rural areas.
Radio Frequency (RF) communications are generally reliable and well
understood but cannot support emerging data rate needs unless they use a large
portion of the precious radio spectrum. Free Space Optical (FSO) communications
[1] offer enormous data rates but operate much more at the mercy of the
environment. The perennial limitations of FSO communications are manifested in
the channel attributes of scintillation (optical turbulence) and path
obscurations. Both phenomena reduce the availability of the optical channel to
support reliable communications. Since RF paths are relatively immune to the
same phenomenology, combining the attributes of a high data rate but burst link
(FSO) with the attributes of a low data rate (by comparison) but reliable link
(RF) could yield attributes better than either one alone: high availability
with high data rates.
This is one
of our active areas of research.
{1] Lasers that transmit data at
over 1 gigabyte per second may be coming to your neighborhood, The FEATURE
Journal,
Acknowledgments
This project is a collaborative research between the
AT&T Shannon Labs and the CICTR of The Pennsylvania State University.
10GBASE-T Transmission over Standard Category-5 or 6 Copper
Cable
With the increasing popularity of multimedia services
supplied over a fixed network, services such as: web browsing, video conferencing
and video-on-demand, it is only a matter of time before users will demand
higher bandwidth
Our presentation to the IEEE 802.3 Standards Committee, the
10GBASE-T Study Group can be downloaded from the 10GBASE-T Study Group Meeting
site at: http://www.ieee802.org/3/10GBT/public/nov03/index.html
Ø
Nexans White Paper: Nexans efforts on 10Gbe over UTP
Ø
Nexans White Paper: Dynamic
Performance: Assessing Cabling Claims for 10GBASE-T, Nexans,
May 2004.
Ø
Penn-State Research
News: Copper wire shown to be competitive with fiber optic
cable for LANS
Ø Eurek-Alert: Copper wire ……………..
Ø
HimTimes: Copper Wire……………
Ø Continuity Central: Copper wire broadband LANS shown to have advantages over fibre optic cable
Ø
Today's focus: Cat-6 may go
farther…………..
Ø
Wire and Cable
International Overview (page-3): Copper seen as competition for FO cable
Ø Monitor: Copper wire competitive………….
Ø
The WAI Connection: Can copper wire match……….
Ø
BrightSurf:
Copper wire shown to be competitive
Ø
Speed guide: Copper
wire………………
Ø
UOL Inovacao: Cobre pode
substituir fibra óptica na transmissão de dados
Ø
CTFQ – O Potal Oficial
da……………
Ø
Business Week: Developments to watch
Acknowledgments
This research is supported by
the Pittsburgh Digital Greenhouse through a grant
from the commonwealth of PA, Department of Community and Economic Development,
International Copper Association (
Fixed Wireless Access Systems;
Multimedia-Teleconferencing
Robust and Error-Resilient Multimedia Video-Teleconferencing
over UNII-Band
Fixed Wireless Channels
I.
Starting
with H.263+ and H.323 standards for packet-video compression encoding /
decoding, appropriate measures are being added to make the compression
algorithms more error- resilient on Fixed Wireless Fading Channels.
II.
In
applications involving image, video and other mixed media transmissions, the
channel as seen by the higher layers is not the same old natural
continuous-time physical channel. It is a modified channel due to the error
correction mechanisms used on the physical layer. Thus, the uncorrected errors
affect the design of video encoding algorithms.
A
UNII-Band 5.8 GHz, frequency hopping digital radio, using an adaptive signal
constellation, on a metropolitan-area nearly Line-of-Sight (LOS) radio link
provides a wireless test-bed for Quality-of-Service (QoS)
measurements. We are performing on-going status monitoring of a nearly
point-to-point radio link on the University Park campus of The Penn-State
University. This status monitoring includes monitoring link throughput, outage,
dropped packets, - - - etc, on the established radio link. This is required
over variations of weather, seasons, etc. We are developing and implementing a
means of measuring and logging link performance at TBD time intervals on this
UNII-band radio link. A major goal here is to identify the validity conditions
for fading assumptions on this link.
Selected
Papers
- J.
Yun, W. Jeong, M. Kavehrad, “Throughput Analysis of Selective Repeat
ARQ Combined with Adaptive Modulation for Fading Channels,”
Proceedings of the MILCOM’02, Anaheim, CA, October 2002.
- K.
Muhonen and M. Kavehrad,
“Amplifier Linearization with Memory for Broadband Wireless
Applications,” Proceedings of the Thirty-Fifth Asilomar
Conference on Signals, Systems and Computers, Pacific Grove, CA., November
2001.
- W.-C.
Jeong and M. Kavehrad,
“Dynamic-TDD and optimum Slot-Allocation in Fixed Cellular
Systems,” Proceedings of the IEEE Vehicular Technology Conference,
- Ravindran, H. Liu, I. Agoren,
A. Lackpour, D. Miller, M. Kavehrad,
J. Doherty, “Mobile Multimedia Services for Third Generation
Communications Systems,” Proceedings of the IEEE Vehicular
Technology Conference, Atlantic City, October 2001.
- J.
Li, M. Kavehrad, “Multi-Carrier
Orthogonal-CDMA for Broadband Fixed Wireless Applications,”
Proceedings of the IEEE Vehicular Technology Conference,
- Alexander
Lackpour, M. Kavehrad
and Scott Thompson, “Architecture and Predicted Performance of an
IEEE 802.11b-like WMAN Transceiver at 5.8GHz,” Proceedings of the Third IEEE Workshop on Wireless Local Area Networks,
Boston-Mass., September 2001. PRESENTATION .
- M.
Kavehrad, "Next Generation Wireless
Communications Systems," Plenary Speaker, MWSCAS'2000, Lansing,
Michigan, August 2000.
- J.
Li, S. Farahvash, M. Kavehrad,
R. Valenzuela "Dynamic TDD and Fixed Cellular Networks," IEEE
Communications Letters, Vol. 4, No. 7, July 2000.
- S.
Farahvash, M. Kavehrad,
J. Li, S. D. Thompson," Using Collision Avoidance Frequency Hopping
Technique in a Fixed Wireless Network with Star Topology," Proceedings
of the IEEE WCNC'2000, Chicago, September 2000.
- K.J.
Muhonen, M. Kavehrad,
R. Krishnamoorty, "Look-Up Table Techniques
for Adaptive Digital Pre-distortion, a Development and Comparison,
"IEEE Trans. on Vehicular Tech., Vol. 49, No. 5, September 2000.
- S.
Farahvash, M. Kavehrad,
"A Statistical Channel Model for Wave Propagation in Millimeter-Waves
Range; LMDS Application," Proceedings of PIMRC'99, Osaka, Japan,
September 1999.
- K.
Akhavan, S. Farahvash,
M. Kavehrad, N. Mehravari
" QoS Provisioning for Wireless ATM by
Variable-Rate Coding," Proceedings of WCNC'99, New Orleans, USA,
September 1999.
- J.
Li, K. Muhonen, M. Kavehrad,
"Digital Pre-distortion Linearizer for
Multi-Carrier Spread Spectrum," Proceedings of RAWCON'99, Denver,
Colorado, August 1999.
- J.
Li, M. Kavehrad, "A Multiple Access Scheme
for LMDS, based on OFDM, O-CDMA and Sectored Antennas," Proceedings
of ICC'99, Vancouver, CANADA, June 1999: PRESENTATION
- Kathleen
Muhonen, M. Kavehrad,
"Amplifier linearization for the Local Multipoint Distribution
Services Application," Proceedings of PIMRC'98,
- John
J. Metzner, Reliable Data Communications,
Academic Press, 1998.
- H.
Ohtsuka, O. Kagami, S.
Komaki, K. Kohiyama, M. Kavehrad,
"256-QAM Sub-carrier Transmission Using Coding and Optical Intensity
Modulation in Distribution Networks," IEEE/LEOS Photonics Technology
Letters, April 1991.
- M.
Kavehrad, E. Savov,
"Fiber-Optic Transmission of Microwave 64-QAM Signals," IEEE
Journal on Selected Areas in Communications, Vol. 8, No. 7, Sept. 1990,
pp. 1320-1326 and ICC Proceedings, Atlanta, April 1990.
- I.M.
Habbab, M. Kavehrad
and C-E. Sundberg, " ALOHA with Capture
Over Slow and Fast Fading Radio Channels with Coding and Diversity,"
IEEE Journal on Selected Areas in Communications, Vol. 7, No. 1, pp.
79-88, January 1989.
- M.
Kavehrad, “A Countermeasure to Improve Outage Performance of
Interference-Limited Microwave Radio Links,”
Canadian Journal of Electrical & Computer Engineering, Vol. 16, No. 1,
January 1991.
- M. Kavehrad,
"A Hybrid Radio Model and its Performance in RF Interference
Environments," Technical Memorandum, AT&T Bell Laboratories,
April 1988.
- M.
Kavehrad, "Design and Performance
Considerations for the Hybrid Atmospheric Optical/Digital Microwave
Network Systems," Technical Memorandum, AT&T Bell Laboratories,
December 1987.
- M.
Kavehrad, G.E. Bodeep,
"Design and Experimental Results for a Direct-Sequence
Spread-Spectrum Radio using Differential Phase Shift Keying Modulation for
Indoor, Wireless Communications," IEEE Journal on Selected Areas in
Communications, pp. 815-823, June 1987.
- M.
Kavehrad, P.J. McLane
and C-E. Sundberg, "On the Performance of
Combined QAM and Convolutional Codes for
Cross-Coupled Multidimensional Channels," IEEE Trans. on
Communications, pp. 1190-1201, December 1986.
- M.
Kavehrad, J. Salz,"Cross-Polarization
Cancellation and Equalization in Digital Transmission Over
Dually-Polarized Multipath Fading
Channels," AT&T Technical Journal, Vol. 64, No. 10, December 1985.
- M.
Kavehrad, P.J. McLane,
"Performance of Low-Complexity Channel-Coding and Diversity for
Spread-Spectrum in Indoor, Wireless Communication," AT&T
Technical Journal, Vol. 64, No. 8, pp. 1927-1966, October 1985.
Acknowledgments
- This
research has been supported by the National Science Foundation
(NSF) Grant Number CCR-9902846, The Ben Franklin
Partnership Program of Pennsylvania Pittsburgh Digital Greenhouse,
Lockheed Martin Philanthropy and Lucent Technologies.
Optical Frequency-Encoded CDMA Switch --- Amplitude
Encoding
Of Broadband Sources (Space-Time Coding)
- D. Zaccarin,
M. Kavehrad, "An Optical CDMA System Based
on Spectral Encoding of LED," IEEE/LEOS Photonics Tech. Lett. Journal, Vol. 5, No. 6, April 1993.
- M. Kavehrad,
D. Zaccarin, "Optical
Code-Division-Multiplexed Systems Based on Spectral Encoding of
Non-coherent Sources," Jour. of Lightwave
Tech., Vol. 13, No. 3, March 1995.
- M. Kavehrad,
E. Simova, "Optical CDMA by Amplitude
Spectral Encoding of Spectrally-Sliced Light-Emitting-Diodes,"
Proceedings of IEEE ISSSTA, Mainz-Germany, September 1996: PRESENTATION
- D.
Zaccarin, M. Kavehrad,
"Optical CDMA with New Coding Strategies and New Architectures to
achieve Bipolar Capacity with Unipolar
Codes,"