next generation wireless networks: smart radios
DESCRIPTION
NeXt Generation Wireless Networks: Smart Radios. Suzan Bayhan [email protected] http://satlab.cmpe.boun.edu.tr http://www.cmpe.boun.edu.tr//~bayhan. Outline. Problem Definition & Motivation Software Defined Radio + Cognitive Radio Standardization What about Satellites? - PowerPoint PPT PresentationTRANSCRIPT
1/37NETLAB Seminar 7 March 2007
NeXt Generation Wireless Networks: Smart Radios
Suzan Bayhan
[email protected]://satlab.cmpe.boun.edu.tr
http://www.cmpe.boun.edu.tr//~bayhan
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Outline
Problem Definition & Motivation
Software Defined Radio + Cognitive Radio
Standardization
What about Satellites?
Conclusion and References
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Motivation
Going wireless more and more...
Lack of interoperability bw. different technologies
Lack of spectrum (???)
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Spectrum Facts
Fixed Spectrum Assignment
Bandwidth is expensive and good frequencies are taken
Recent measurements by the FCC in the US show 70% of the allocated spectrum is not utilized
Time scale of the spectrum occupancy varies from msecs to hours
More clever radio
Frequency Agility----SPECTRUM SHARING
SOLUTIONSOLUTION
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Solution
Joseph Mitola 1992 Software Defined Radio(SDR)
radio primarily defined insoftware, which supports a broad range offrequencies, and its initial configurations can bemodified for user requirements.
Joseph Mitola 1999Cognitive Radio(CR)
SDR + Intelligence
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Outline
Problem Definition & Motivation
Software Defined Radio + Cognitive Radio
Standardization
What about Satellites?
Conclusion and References
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SDR properties
Reconfigurable
Easily Upgradeable
Responds to the changes in the operating environment
Lower maintenance cost
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If SDR technology is properly applied...it will facilitate this single platform design, and will also provide a path towards the realization of concepts such as
Reconfigurability (single platform concept)
run-time reconfiguration (run-time bug fixes)
and eventually self-governed learning (cognitive) radio.
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FINAL GOAL...
UNIVERSAL WIRELESS DEVICE
that can seamlessly handle a range of frequencies, modulation techniques, and encoding schemes.
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Some definitionsPrimary User (Licensed User)
the user which has an exclusive right to a certain spectrum band.In other words, the license holders...
No need to be aware of cognitive usersNo additional functionalities or modifications needed
Secondary User (Unlicensed User)Cognitive-radio enabled users
Lower priority than PUs
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SPECTRUM HOLEA spectrum hole is a band of frequencies assigned to a primary user, but, at a particular time and specific geographic location, the band is not being utilized by that user.
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Definition (1)
In the 1999 paper that first coined the term “cognitive radio”, Joseph Mitola III defines a cognitive radio as
“A radio that employs model based reasoning to achieve a specified level of competence in radio-related domains.”
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Definition (2)
Simon Haykin defines a cognitive radio as “An intelligent wireless
communication system that is aware of its surrounding environment (i.e., outside world), and uses the methodology of understanding-by-building to learn from the environment and adapt its internal states to statistical variations in the incoming RF stimuli by making corresponding changes in certain operating parameters (e.g., transmit-power, carrierf requency, and modulation strategy) in real-time, with two primary objectives in mind:
· highly reliable communications whenever and wherever needed;
· efficient utilization of the radio spectrum.
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Properties
Cognitive radio propertiesRF technology that "listens" the spectrum Knowledge of primary users’ spectrum usage as a function of location and timeRules of sharing the available resources (time, frequency, space)Embedded intelligence to determine optimal transmission (bandwidth, latency, QoS) based on primary users’ behavior
Cognitive radio requirements
co-exists with legacy wireless systems uses their spectrum resources does not interfere with them
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Main Cognitive Functions
Spectrum Sensing
Spectrum Management
Spectrum Mobility
Spectrum Sharing
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But...
Hard to design a radio front end in software...
A single antenna with good gain across a wide range of frequencies.
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9 levels of CR functionality
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How Does a Cognitive Radio Get So Smart?
External Intelligence Sources
OrientEstablish Priority
PlanNormal
Generate Alternatives(Program Generation)Evaluate Alternatives
Register to Current Time
DecideAlternate Resources
Initiate Process(es)(Isochronism Is Key)
Act
Learn
Save Global States
Set DisplaySend a Message
ObserveReceive a Message
Read Buttons
OutsideWorld
NewStates
The Cognition Cycle
PriorStates
Pre-process
Parse
ImmediateUrgent
Infer on Context Hierarchy
OBSERVE-ORIENT-DECIDE-ACT
OODA loop
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SPECTRUM SENSING
Goal: Reliably detect presence of a Primary UserDifferent Primary Users have different sensitivity thresholdsThree possible approaches:1. Matched Filter2. Energy detector3. Cyclostationary Feature detectorLocal Spectrum Sensing– Each user makes decision on a Primary User presence based on its local sensing measurementsCooperative Spectrum Sensing
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Outline
Introduction
Software-defined radio-Cognitive Radio
StandardizationResearch Issues
References
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Standardization efforts
IEEE 802.22 WRAN
SDR Forum
GNU Radio Project
DARPA xG
JTRS
North R., Browne N., Schiavone L., Joint Tactical Radio System- Connecting the GIG to the tactical Edge, MILCOM 2006, 23-25 Oct, 2006, Washington, DC. USA.
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TThe Vanu Software Radio GSM he Vanu Software Radio GSM Base StationBase Station from Vanu can support multiple cellular technologies and frequencies at the same time and can be modified in the future without any hardware changes.
GSM + CDMA waveforms
Written in C++, running under the Linux OS.
FCC approves first software-defined radio...2004
IEEE Spectrum, January 2007
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Challenges and Research Issues
Hardware
Learning Mechanisms
Routing and Upper layer Issues (Networking, QoS)
Developing spectrum sharing behaviors
Sensitive detection
Frequency assignment negotiation
Resource allocation
Security (Unintentional config..)
Integration with “spectrum market”
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• Optimize transmission parameters
• Adapt rates through feedback
• Negotiate or opportunistically use resources
Physical Layer
MAC Layer
Network Layer
Transport Layer
Application Layer
OFDM transmissionSpectrum monitoring
Dynamic frequency selection,
modulation, power control
Analog impairments compensation
Routing, System Management, QoS and other upper layer issues...
Cross-layer design
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Some SDR platforms
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Outline
Problem Definition & Motivation
Software Defined Radio + Cognitive Radio
Standardization
What about Satellites?
Conclusion and References
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What about satellites!!!
Satellite knowledge chunk in Mitola’s book (2000)
Software Radio in Space Segment by Catherine Morlet, European Space Agency (ESA), 2006.
How can satellites take role in the game?Or can they?
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WAND (softWare rAdio techNology in space segment stuDy)
Software Radio in Space Segment Final Report v1.1
20 April 2006
Alcatel Alenia Space France (FR)
Alcatel Alenia Space Espana (SP)
Atos Origin (SP)
Carlo Gavazzi (IT)
The introduction of Software Radio Technology at the satellite level has particular interest for:
• Improving the functionalities of a payload/repeater. • Introducing standard updates. • Modifying the mission of a payload/repeater. • Introducing new concepts (e.g. adaptative coding and modulation).
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Satellite Lifetime ~ 10-15 years
Standards and associated algorithms are going to evolution during this period putting the satellite in risk of obsolescence during its lifetime period.
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Other issues
Intelligence in satellite
Spectrum Manager(!) Can it be logical?
Policy Updates by satellites (Broadcasts)
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Simulation Scenario
A 1000 m X 1000 m areaSome WLAN users Some SUs (mobile)
High Altitude Platform decides on frequency and other transmission parameters based on feed-back from the SUs and the policies from LEO or Command Center.
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Performance Evaluation
Effect of number of SUs
Overall Throughput
SU Throughput
Interference by SUs
Spectrum Utilization
RESULTS COMING SOON!
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To conclude...
More efficient use of spectrum (may decrease cost of the services like GSM calls)
Flexibility (Interoperability)
Dreaming of a universal device!
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References
S. Haykin, "Cognitive radio: brain-empowered wireless communications," IEEE Journal Selected Areas in Communications, vol. 23, no. 2, pp. 201 - 220, 2005. J. Mitola III, “Software radios survey, critical evaluation and future directions,” IEEE AES Systems Magazine, Vol. 8, No. 4, pp. 25-36, Apr. 1993.I.F. Akyıldız, W-Y.Lee, M.C. Vuran, S.Mohanty,”NeXt generation/dynamic spectrum access/cognitive radio wireless networks: A survey”, Computer Networks Journal (Elsevier), vol. 50, pp. 2127-2159, September 2006. David Scaperoth, Cognitive Software Defined Radio: Applications of Cognitive SDR using the GNU Radio and the USRP, 09/09/05.http://www.cognitiveradio.wireless.vt.edu/dokuwiki/doku.php?id=research:radio_hw_swhttp://web.syr.edu/~ejhumphr/http://bwrc.eecs.berkeley.edu/Research/Cognitive/publications.htmNeli Hayes, JTRS Specification: The past, the present, and the future..., MILCOM 2005.J. Powell, “Public safety perspectives on cognitive radio–Potential and pitfalls,” presented at the Conf. Cognitive Radios, Technology Training Corporation, Las Vegas, NV, Mar. 15–16, 2004.J. D. Shilling, “FCC rulemaking proceeding on cognitive radio technologies,” presented at the Conf. Cogn. Radios, Technol. Training Corp., Las Vegas, NV, Mar. 15–16, 2004.IEEE Spectrum, January 2007.
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Thank You!Questions?
www.satlab.cmpe.boun.edu.tr