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

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IEEE1900.4

Network reconfigurati

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Terminal reconfigurati

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Terminal reconfigurati

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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

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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

kuncoro@telkom.cc Twitter @kuncoro Mobile +62-21-3375-8000