Cognitive Radio for Future InternetSurvey on CR Testbed & Product

Munhwan Choi

Multimedia & Wireless Networking Laboratory

School of Electrical Engineering and INMC

Seoul National University, Seoul, Korea

Contents

� Software Defined Radio (SDR)

� Examples of Cognitive Radio Project & Testbed

� Future of Cognitive Radio

� Standardization

� Conclusion

Software Defined Radio (SDR)

� Radio’s physical layer behavior is primarily defined in software

� Accepts fully programmable traffic & control information

� Supports broad range of frequencies, air interfaces, and application software

� Changes its initial configuration to satisfy user requirements

How is a Software Radio Different from Other Radios? –

Application, Design, Upgrade

Software Radio

� Dynamically support multiple variable systems, protocols and interfaces

� Interface with diverse systems

� Provide a wide range of services with variable QoS

� Conventional Radio +� Software Architecture� Reconfigurability� Provisions for easy

upgrades

� Ideally software radios could be “future proof”

� Many different external upgrade mechanisms

� Over-the-Air (OTA)

ConventionalRadio

� Supports a fixednumber of systems

� Reconfigurabilitydecided at the time of design

� May support multiple services, but chosen at the time of design

� Traditional RF Design� Traditional Baseband

Design

� Cannot be made “future proof”

� Typically radios are not upgradeable

Cognitive Radio

� Can create new waveforms on its own

� Can negotiate new interfaces

� Adjusts operations to meet the QoS required by the application for the signal environment

� SDR +

� Intelligence

� Awareness

� Learning

� Observations

� SDR upgrade mechanisms

� Internal upgrades

� Collaborative upgrades

Cognitive Radio & SDR

� Some believe SDR is not necessary for cognitive radio� Cognition is a function of higher-layer application

� Cognitive radio without SDR is limited� Underlying radio should be highly adaptive

� Wide QoS range

� Better suited to deal with new standards� Resistance to obsolescence

� Better suited for cross-layer optimization

Example SDR: GNU Radio

� What is GNU Radio?� GNU Radio is a set of S/W signal processing building blocks that allow users to create their own S/W radio

� GNU Radio is an open-source software defined radio (SDR) platform

� Why GNU Radio?� Attempts to solve the complexity issues of both H/W and S/W of SDR

� Modular (use with most any GPP)

� S/W used on Windows, Linux, Mac

Implementing a SDR with the GNU Radio

USRP - Universal Software

Radio Peripheral

GNU Radio software

- core s/w

- user made s/w

Courtesy of http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html

GNU Radio S/W

available at www.gnuradio.org

Summary of Trends

� SDR need is driven by two principal factors� New applications

� Cognitive radio, collaborative radio & advanced roaming� Increased number of protocols to support� Potential cost reductions

� ADC is no longer the key bottleneck� Flexible RF products starting to come to market� Software architecture critical

� Additional technology supporting architectural approach available

� Reconfigurable hardware needed� General-purpose hardware approach is likely to be unable to

keep up with wireless bandwidth growth� Component-based reconfigurable hardware architectures present

powerful solution� Multi-core processors show promise

SDR Market Today

� Military� JTRS program created multi-billion dollar SDR market� DARPA neXt Generation (XG) Communications project� International derivatives of JTRS/SCA (EU, Canada, etc)

� Commercial� Digital RF processors (TI Bluetooth and GSM)� Multi-standard basestation implementations (Vanu)� SDR handsets probably within 3 years as low power processors become available

� Regulatory� Recent FCC directive to ensure code and RF compatibility

Mark Scoville, Stephen Berger,

Richard C. Reinhart, Dr. Jeffrey

E. Smith,

“THE SOFTWARE-DEFINED

RADIO & COGNITIVE

RADIO

INTER-CONSORTIA

AFFILIATION”, Software

Defined Radio Technical

Conference 2006, Nov. 2006

DARPA neXt Generation Program - Motivation

� XG is trying to Develop the Technology and System Concepts to Dynamically Access Available Spectrum

� Problems:� Spectrum Scarcity

� Spectral resources are not fully exploited� Opportunities exist in space, time, frequency� Current static spectrum allocation prevents efficient spectrum utilization

� Deployment difficulty� Different policy regimes in different countries� Deployment of communication networks tedious� Of particular interest in military applications

� Proposed solution:� Complement static spectrum allocation with "Opportunistic spectrum access"

� Primary users� Licensed� Priority to use allocated spectrum� Guaranteed QoS

� Secondary users� Non-licensed� Can allocate unused spectrum among themselves� Have to vacate bands if required by primaries

Unless otherwise stated, all the information in this description of the DARPA XG program

is based on the XG Vision rfc, available online: http://www.darpa.mil/ato/programs/xg/

React

Formulate Best

Course of Action

ReactReact

Formulate Best Formulate Best

Course of ActionCourse of Action

Adapt

Transition

network to new

emission plan

AdaptAdapt

Transition Transition

network to new network to new

emission plan emission plan

Characterize

Rapid waveform

determination

CharacterizeCharacterize

Rapid waveform Rapid waveform

determinationdetermination

Sense

Real time, Low-

power, wideband

monitoring

SenseSense

Real time, LowReal time, Low--

power, wideband power, wideband

monitoringmonitoring

AutonomousAutonomous

Dynamic Dynamic

SpectrumSpectrum

UtilizationUtilization

DARPA neXt Generation Program: Research Goals

� Development of technologies that enable spectrum agility

� Sensing and characterization of the (RF-) environment

� Identification of unused spectrum ("opportunities")

� Allocation and exploitation of opportunities

� Development of standards for a software based policy regime to enable policy agility

� Decoupling of policies from implementation

� Define abstract behaviors, e.g., "Channel can be vacated within t sec."

� Policies implement (dictate) behaviors

� Protocols instantiate behaviors

� Traceability

� All behaviors must be traceable to policies:

� Each operational mode a device is capable of is tied to a specific policy which allows it

� Software based

� Spectrum use policies have to be machine understandable

� Policy constraints can be implemented "on-the-fly" via software downloads

XG Dynamic Spectrum Sharing Field Test Results

� M. McHenry, E. Livsics, T. Nguyan, and N. Majundar, “XG Dynamic. Spectrum Sharing Field Test Results,” DYSPAN 2007, Apr. 2007

CR Test-bed under development – Virginia Tech.

AP (Data

Collection Node)

AP (Data

Collection Node)

AP (Data

Collection Node)

Interference

Detection,

Classification,

Location

OSSIE Framework

Arbitrary

Waveform

Generator

AP (Data

Collection Node)

AP (Data

Collection Node)

AP (Data

Collection Node)

Interference

Detection,

Classification,

Location

OSSIE Framework

Arbitrary

Waveform

Generator

NeighborWLANs

Ethernet

Actions

Cordless Phone Bluetooth

MWOL

Tektronix

TDS694C:

Digital Real-time

Oscilloscope

Tektronix

RSA3408A: Real-

Time Spectrum

Analyzer

Distributed MeasurementDistributed Measurement

Collaborative ProcessingCollaborative ProcessingObservations

Analysis and decision

REM online updating

TV station

Cognitive Radio Testbed - Georgia Tech

� Maximum H/W flexibility

� Full S/W Control : MATLAB

The Future of Cognitive Radio

� Public Safety - Interoperability� Focus on multi-agency interoperability since 9/11/2001

� Cognitive radio technology can improve interoperability by enabling devices to bridge communications between jurisdictions using different frequencies and modulation formats.

� Such interoperability is crucial to enabling public safety agencies to do their jobs.

IEEE 802.22

� WRAN system based on 802.22 will make use of unused TV broadcast channels

� Interoperable air interface for use in spectrum allocated to TV Broadcast Service

� Allows Point to Multi-point Wireless Regional Area Networks (WRANS)

� Supports a wide range of services� Data, voice and video� Residential, Small and Medium Enterprises� Small Office/Home Office (SOHO) locations

IEEE Project 1900 (P1900)

�� The IEEE P1900 Standards Group was established The IEEE P1900 Standards Group was established

in 1Q 2005 jointly by the IEEE in 1Q 2005 jointly by the IEEE Communications Communications

SocietySociety ((ComSocComSoc) and the IEEE ) and the IEEE Electromagnetic Electromagnetic

Compatibility (EMC) Society.Compatibility (EMC) Society.

�� The objective of this effort is to develop The objective of this effort is to develop

supporting standards related to new technologies supporting standards related to new technologies

and techniques being developed for next and techniques being developed for next

generation radio and advanced spectrum generation radio and advanced spectrum

management.management.

IEEE P1900 Working Group:

� IEEE P1900.1 Working Group:

� Objective document: “Standard Terms, Definitions and Concepts for Spectrum Management, Policy Defined Radio, Adaptive Radio and Software Defined Radio.”

� Purpose: This document will facilitate the development of these technologies by clarifying the terminology and how these technologies relate to each other.

� IEEE P1900.2 Working Group:

� Objective document: “Recommended Practice for the Analysis of In-Band and Adjacent Band Interference and Coexistence Between Radio Systems.”

� Purpose: This standard will provide guidance for the analysis

of coexistence and interference between various radio services.

IEEE P1900.3 Working Group:

� Objective document: “Recommended Practice for Conformance Evaluation of Software Defined Radio (SDR) Software Modules.”

� Purpose: This recommended practice will provide guidance for validity analysis of proposed SDR terminal software prior to physical programming and activation of SDR terminal components.

IEEE 802.11h & 802.15.3a

� IEEE 802.11h

� 802.11h helps WLANs share spectrum

� 801.11h implements two methods to help spectrum sharing:

� Dynamic Frequency Selection (DFS)

� Transmission Power Control (TPC)

� DFS is used to select the appropriate spectrum for WLAN

� TPC is used to manage WLAN networks and stations for Reduction of interference, Range control (setting borders for WLAN), and Reduction of power consumption (beneficial in laptop use e.g.)

� IEEE 802.15.3a

� Multiband OFDM for Personal Area Network

� Wireless USB2.0 (480Mbps) at 5 meters distances

� Cognitive Radio - Plausible Application to UWB Regulation

� Very fast spectrum sculpting via OFDM technology with wide bandwidth 528MHz

� QoS Support

� QoS can be supported by controlling the number of sub-carriers

Hurdles in CR

� FCC Development Policies� The process and rules

governing how frequencies and waveforms are selected and approved for use by cognitive equipment must be addressed.

� Software Flexibility� Interface with policy

updates

� Real-life functionality� CR devices are smart

enough to understand user request and surrounding environments

� Network availability for CR� Network needs to announce

their availability to CR

� Flexible or Reconfigurable Hardware

� Requires a language and protocols for initial interfacing with software and validation for existing devices as policies change across time and space

� Software Architectures� More dynamic than SCA

Predictions for Future Evolution

Time

SDR with high

ASIC content

Re-

programmable

for fixed

number of

systems

Factory

reprogrammable

Increased use

of

reconfigurable

hardware

Limited

reconfiguration

by userEarly

cognition

Mid-level

cognition

Cognitive

radios

2005 2007 2010

Adaptive

spectrum

allocation

Conclusion

� The testbed will serve, not only as a technical development platform, but also as an educational tool that provides insight and deep understanding of cognitive radio technology.

� Dell, HP, Google, and others want the FCC to sign off on letting consumer devices utilize the "white space."

Reference

� Dr. Jeffery H. Reed. “Understanding the Issues in Software Defined Cognitive Radio”

� Ettus Research, .Universal Software defined radio Peripheral (USRP) ., http://www.ettus.com/custom.html

� M. McHenry, E. Livsics, T. Nguyan, and N. Majundar, “XG Dynamic. Spectrum Sharing Field Test Results,” DYSPAN 2007, Apr. 2007

� Y. Hur, J. Park, K. Kim, J. Lee, K. Lim, C.-H. Lee, H.S. Kim, and J. Laskar, “A Cognitive Radio (CR) Testbed System Employing A Wideband multi-Resolution Spectrum Sensing (MRSS) Technique,” VTC 2006, Sep. 2006