Cognitive Radio Introduction & Main Issues
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Transcript of Cognitive Radio Introduction & Main Issues
Cognitive RadioIntroduction & Main IssuesKuncoro WastuwibowoIEEE Indonesia Section
Cognitive RadioY U NO
make wireless systems
computationally intelligent ??
Rationale & History
Rationale behind CRThe current policies of spectrum block result in
inefficiency of spectrum usage. In some block, the spectra are saturated, whereas other bands are underused. The improvement will need a flexible yet regulated use of spectrum band.
Mobile and multi-device lifestyle currently requires multi-band and multi-platform wireless technology, which should be simplified and/or future-enhanced with software-defined wireless technology.
Context-aware service and applications could be improved with cross-layer optimization including the flexible use of spectrum.
CR Ideal Objective
Device Cognitive Radio
Generic TX / RX
Most-Effective (or Any
Available Spectrum)
CR-like Systems
Standardisation
Standards for CR AspectsAspects Covering Standard BodiesDefinition IEEE Dyspan, ETSI, ITU-RCoexistence IEEE 802.19, IEEE DyspanSoftware-Defined Radio
IEEE Dyspan, SDR Forum, ITU-R, OMG
Radio Interfaces IEEE 802.22, 3GPPHeterogeneous Access
ETSI, IEEE Dyspan
Spectrum Sensing IEEE 802.22, IEEE DyspanTestingNetworkingSecurity
IEEE Standardisation
• IEEE Communications Society & IEEE Electromagnetic Compatibility Society established IEEE P1900 Standard Committee to develop supporting standards for dynamic spectrum management.
2005
• IEEE Standard Board reorganised P1900 SC as Standards Coordinating Committee 41 (SCC41), Dynamic Spectrum Access Networks (DySPAN).
2007
• SCC41 voted to be organised under IEEE Communications Society Standards Board, and was renamed as IEEE DySPAN SC (Standard Committee).
2010
IEEE DySPAN SC Work Scope
DSA radio systems and networks with the focus
on improved use of spectrum
New techniques and methods of DSA
including the management of radio
transmission interference
Coordination of wireless technologies
including network management and
information sharing amongst networks deploying different
wireless technologies
IEEE Dyspan SC Working Groups• Terminology and Concepts for Next Generation Radio
Systems and Spectrum Management1900.1• Interference and Coexistence Analysis1900.2• Conformance Evaluation of Software Defined Radio (SDR)
Software Modules1900.3• Architectural Building Blocks Enabling Network-Device
Distributed Decision Making in Heterogeneous Wireless Access Networks1900.4
• Policy Language and Policy Architectures for Managing Cognitive Radio for Dynamic Spectrum Access Applications1900.5
• Spectrum Sensing Interfaces and Data Structures for Dynamic Spectrum Access and other Advanced Radio Communication Systems1900.6
• Radio Interface for White Space Dynamic Spectrum Access Radio Systems Supporting Fixed and Mobile OperationP1900.7
CR Aspects in IEEE 802 Standards
• 802.22 is a wireless communication at 54–863 MHz. It has an arrangement related to the identification of the PUs and defining the power levels so as not to interfere with the adjacent bands. BS controls all the CPE’s decisions as to when to send data and the channels to use. CPE senses the spectrum in its vicinity, helping in distributed detection of PU activity.
IEEE 802.22
• 802.16 (WiMAX) has its own set of standards that support CR-like functionalities, including methods of efficient coexistence of multiple BWA systems. It also discussed interference analysis and coexistence issues for BWA networks in its bands.
IEEE 802.16
CR Aspects in IEEE 802 Standards
• 802.15 (WPAN) works in the license-exempt bands and also have their own set of standards related to coexistence.
IEEE 802.15
• Coexistence mechanisms are also included in 802.11 WiFi standards, including dynamic frequency selection and transmit power control for coexistence with satellite and radar systems operating in the 5 GHz band.
IEEE 802.11
• This standard defines general coexistence metrics for all IEEE 802 networks working in the unlicensed bands. Although focusing on IEEE 802 networks, the guidelines of the standard can be applicable to other unlicensed wireless systems
IEEE 802.19
Functionality
Definitions
• is a type of wireless transmission in which communication systems are aware of their environment and internal state and can make decisions about their radio operating behavior based on that information and predefined objectives.
Cognitive radio (CR)
• is the real-time adjustment of spectrum utilisation in response to changing circumstances and objectives.
Dynamic Spectrum Access (DSA)
Adaptive Wireless SystemsRadio Type Platform Reconfiguration &
AdaptabilityIntelligence
Hardware Hardware Minimal NoneSoftware HW/SW Automatic MinimalAdaptive HW/SW Automatic /
predefinedMinimal / none
Reconfigurable
HW/SW Manual / predefined Minimal / none
Policy-based HW/SW Manual (database) / automatic
Minimal / none
Cognitive HW/SW Full Artificial / machine learning
Intelligent HW/SW Full Machine learning / prediction
CR Functionality
Reconfigurable Radio Platform
TX
RX
Policies, Rules, etc
Decision Database
Learning & Reasoning
Sensing
Radio Environme
nt, User Behaviour,
Device State, etc
CR in Heterogeneous Nextgen Wireless Access
3G 4G WiMAX WiMAX II(806.16m)
WiFi(802.11n)
WiFi NG
DSA-enabledRadios
Network Management
Legacyterminal
1900
.4Te
rmin
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1900
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rmin
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IEEE1900.4
Network reconfigurati
on managemen
t
Terminal reconfigurati
on managemen
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Terminal reconfigurati
on managemen
t
Metropolitan Short-RangeCellular
Heterogeneous Wireless Access
Spectrum Selection: Context
RANContext Information
• RAN radio resource optimisation objectives
• RAN radio capabilities
• RAN measurements• RAN transport
capabilities
TerminalContext Information
• User preferences• Required QoS levels• Terminal capabilities• Terminal
measurements• Terminal geo-
location information• Geo-location-based
terminal measurements
Spectrum Selection: Decision
NRM: Network Reconfiguration
Management• Responsible for
managing composite wireless network (CWN)
• Accepting spectrum assignment policies from Policy block
• Transmit radio resource selection guide to TRM
TRM: Terminal Reconfiguration
Management• Responsible for
managing the terminal, within the framework defined by the NRM, for network-terminal distributed optimisation of spectrum usage
• Accepting radio resource selection guide from NRM
System Architecture
Functional Architecture
Multiple Player Issues:Self-Coexistence
Switch or Stay: Expected Cost Assume:
N = number of networks competing M = number of band
Two networks cannot share a band, because it will suffer the QoS Any interfering network i in a specific band may choose to ‘stay’ or ‘switch’ Expected cost to find a clear channel:
where si, s-i strategy chosen by i and by other network c cost of single switching f(N,M) function that depicts the varying behavior of the
cost with N and M. For example f(N,M) = NM/(M-N)
Challenge Accepted
Switch or Stay: Cost FunctionIf i chooses to stay, possibly:(i) All others will switch, creating clear band for i(ii) All others might stay, wasting the stage, and repeating the
game G(iii)Some networks will switch, while the rest will stay and creating
a subgame G’
The cost function is:
The optimization problem in this game is to find a mechanism of switching or staying such that the cost incurred can be minimized and an equilibrium can be achieved. Assuming all the players (networks) are rational, there might be a set of strategies with the property that no network can benefit by changing its strategy unilaterally while the other networks keep their strategies unchanged (Nash equilibrium).
Switch or Stay: Expected Cost Prob.If:p is the probability to switch and (1-p) is the probability of stayj is the number of other networks willing to switchQj denotes the probability of j networks switching out of other N − 1 networks
Then: the expected costs of i if it chooses to switch or to stay are
OptimisingTo find the optimal value, both equations are equated
Using binomial equations etc,
For any values of N and M, p has a nonzero finite value, thus proving the existence of a mixed strategy Nash equilibrium point.
Switching Cost for N=20• Average system
convergence cost with 20 competing cognitive radio (CR) networks.
• With increase in number of available bands, the convergence cost decreases.
• The convex nature of the curves proves that a point of minima exists for each of the curve. This minima corresponds to the Nash equilibrium strategy (p).
Cost vs N/M Ratio
• System convergence costs following mixed strategy space for a varying network:band ratio (50−90%)
• With an increase in the network : band ratio the system convergence cost increases almost exponentially.
Next Issues
Future of CR: Network Radio
Cognitive
Radio
Network
MAC
PHY Polic
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Next Works to Discuss Spectrum sensing & other
DSA input Sharing technologies Location & context-
awareness Cognitive learning &
adapting Collaborative radio-coverage
and capacity extensions Self-configuring, optimising,
healing technologies Autonomic interoperability
Cognitive routing & prioritisation
Smart antenna management Heterogeneous networks
spectrum management Small cells & spectrum
management Cognitive MIMO Intersystem handoff &
network resource allocation End-to-end QoS, security,
and trust system
Let’s Discuss It !!
Reference Fabrizio Granelli & al. Standardization and Research in Cognitive and Dynamic
Spectrum Access Networks: IEEE SCC41 Efforts and Other Activities. IEEE Communications Magazine, January 2010.
Krzysztof Iniewski (ed). Convergence of Mobile and Stationary Next-Generation Networks. Wiley, 2010.
Lee Pucker. Review of Contemporary Spectrum Sensing Technologies. Report for IEEE-SA P1900.6 Standards Group
Min Song & al. Dynamic Spectrum Access: From Cognitive Radio to Network Radio. IEEE Wireless Communications, February 2012.
Paul Houze & al. IEEE 1900.4 WG: IEEE 1900.4 Standard Overview. Presentation. R. Venkatesha Prasad & al,Cognitive Functionality in Next Generation Wireless
Networks: Standardization Efforts. IEEE Communications Magazine, April 2008. Soodesh Buljore & al. Architecture and Enablers for Optimized Radio Resource
Usage in Heterogeneous Wireless Access Networks: The IEEE 1900.4 Working Group. IEEE Communications Magazine, January 2009.
Kuncoro Wastuwıbowo
Telkom Indonesia Multimedia Division
Senior Service Creation (2010-now)
IEEE Indonesia Section
Vice Chair (2012) Comsoc, Indonesia Chapter
Chairman (2009-2011) Vice Chair (2007-2008)
Internetworking Indonesia Journal
Editor
Contact Mail / Gtalk
[email protected] Twitter @kuncoro Mobile +62-21-3375-8000