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Spectrum Agile Radio. Team 4 Jim Kile Don Little Samir Shah. Structure of Presentation. Definition, why?, and evolution Background concepts White space, measurements Regulatory environment Wireless standards Implementations. Spectrum Agile Radio (SAR).

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Spectrum agile radio

Spectrum Agile Radio

Team 4

Jim Kile

Don Little

Samir Shah

Structure of presentation
Structure of Presentation

  • Definition, why?, and evolution

  • Background concepts

    • White space, measurements

  • Regulatory environment

  • Wireless standards

  • Implementations

Spectrum agile radio sar
Spectrum Agile Radio (SAR)

Use of a licensed radio band by other than the license holders on a non-interfering basis.


  • Wireless LAN’s & MAN’s

  • Palm

  • PocketPC

  • Blackberry

  • Cell phone

  • Wearable computing

  • Other consumer electronics

Evolution of devices
Evolution of Devices

Necessary radio spectrum will not be available in the future


  • Almost all radio bands suitable for wireless communications have been allocated

  • Preliminary studies indicate that much of the radio spectrum is not in use

    • For a significant amount of time

    • At large numbers of locations

Definition radio resources
Definition Radio resources

  • Radio frequency bands

  • Can be used/occupied

  • For certain duration

  • In a certain area

  • Called “footprint”

Definition primary users
DefinitionPrimary Users

  • Conventional legacy users

    • Rightful owners

  • Hardware and protocols have strict priority on spectrum access

  • Should not be required to retrofit to meet secondary user access needs

Definition secondary users
DefinitionSecondary users

  • Spectrum-agile devices

  • Sense environment

  • Adapt to appropriate

    • Frequency

    • Power

    • Transmission schemes

  • Opportunistically access unused spectrum vacated by idle primaries

Definition rules for coexistence
DefinitionRules for Coexistence

  • When a primary user is using the band

    • Secondary users are not allowed to co-exist

  • Channel availability of secondary users determined by the activities and properties of primary users

Definition opportunistic spectrum utilization
DefinitionOpportunistic Spectrum Utilization

  • Usage by Secondary Users

  • On a non-interfering basis

    • Band not used

    • Used in deterministic pattern


Definition spectrum agile radio
DefinitionSpectrum Agile Radio

  • Communicates using available radio resources

  • Licensed to OTHER radio services

  • Without interfering with the operation of licensed radio devices

Definition white space
Definition: White Space

  • Almost all of the radio spectrum has been allocated

  • But, there are areas of the radio spectrum not currently in use by primary user

  • A band is counted as white space when:

    • Wider than 1 MHz and

    • Remains unoccupied for 10 minutes or longer

  • Significance?

    • Resource is scarce

    • Provides an opportunity for dynamic spectrum usage

  • Measuring spectrum white space
    Measuring Spectrum White Space

    • Why?

      • Understand the amount of under-utilized spectrum

    • Conditions

      • 30 MHz to 3,000 MHz (3 GHz)

      • Use a “worse case” location

        • Downtown Washington, DC

        • Both government and commercial spectrum use

      • Several hour duration during high use periods

    Spectrum measurement requirements
    Spectrum Measurement Requirements

    • Elevated location

      • Higher detection probability

      • Eliminates line of site obstacles

    • Use of high quality RF equipment

      • Detection sensitivity

    Whitespace estimate
    Whitespace Estimate

    • Study conducted in June 2003 by the Shared Spectrum Company

    • What constitutes white space for this estimate?

      • Bands ³ 1MHz wide

      • Unoccupied for 10 minutes or longer

    • 62% white space in the licensed spectrum

    Regulatory environment
    Regulatory Environment

    • Bandwidth is a natural resource

      • Heavily regulated

      • Expensive

        • A 3 GHz mobile communications band costs $17 Billion!

      • In the U. S., almost all bandwidth is allocated (licensed)

    Regulatory environment u s fcc models
    Regulatory Environment- U. S. FCC Models

    • Licensed primary user model

      • Set aside for exclusive use

        • Examples: TV and radio

    • Unlicensed non-exclusive use model

      • Set aside for non-exclusive use

        • Examples: ISM band applications such as Wireless LAN (802.11) or Bluetooth

      • Represents a small fraction of the total bandwidth available

    Regulatory environment circa 1940
    Regulatory Environment circa 1940

    • “Dumb device” assumption

    • Tightly regulated to prevent interference

      • Example: Television VHF/UHF band channel allocation

    • No way to share inefficiently used spectrum

    Regulatory environment today
    Regulatory Environment Today

    • Fast processing power and intelligent radios

    • New technology which is more tolerant to interference

      • Spread spectrum

      • Spectrum agile radio

    Regulatory environment today1
    Regulatory Environment Today

    • Introducing underlays/noisefloor rights

    • Developing a noise temperature measure

      • Devices measure the level of interference and transmit according

    • Development of co-existencemodes

    • Allow multiple uses of aspectrum (spectrum agileradio – SAR)

    Regulatory environment spectrum policy task force
    Regulatory EnvironmentSpectrum policy task force

    • Setup by Chairman Michael Powell in June 2002

    • Headed by Paul Kolozdy

    • Purpose

      • Conduct a comprehensive review of spectrum policy

      • Modernize spectrum management and utilization rules

      • “Command and control”  consumer-oriented

    • Submitted findings and recommendations in December 2002

    Regulatory environment spectrum policy task force1
    Regulatory EnvironmentSpectrum Policy Task Force

    “[T]he time is ripe for spectrum policy reform. Increasing demand for spectrum-based services and devices are straining longstanding, and outmoded, spectrum policies. While the Commission has recently made some major strides in how spectrum is allocated and assigned in some bands . . . spectrum policy is not keeping pace with the relentless spectrum demands of the market.”

    Regulatory environment spectrum policy task force2


    Spectrum access versus scarcity

    New methods as a solution to access

    Interference tolerance

    Need to define rights and responsibility


    Modernizing the regulator model

    Increase access to spectrum through the time dimension

    New inferences management standards

    Legislative recommendations

    Regulatory EnvironmentSpectrum policy task force

    Regulatory environment fcc 2005 rule changes
    Regulatory EnvironmentFCC 2005 Rule Changes

    • March 2005, FCC adopts rule changes for smart radios

      • Allows sharing spectrum with primary users without causing harmful interference

      • Regulate emission characteristics rather than the type of service

    • Allows rapid development of new applications

      • Unencumbered by regulatory delays

    Regulatory environment fcc 2005 rule change principles
    Regulatory EnvironmentFCC 2005 Rule Change Principles

    • Provide reasonable security measures to prevent unauthorized software modifications affect the RF operating parameters

    • Manufacturer to supply a high level operational description of the software that controls the radio’s RF characteristics

    • A description of the software security measures employed to prevent unauthorized modifications

    Regulatory environment fcc 2005 rule change principles cont d
    Regulatory EnvironmentFCC 2005 Rule Change Principles cont’d

    • Manufacturers to market radios that have the hardware-based capability to transmit outside authorized United States frequency bands

    • Required software controls to limit operation to authorized frequency bands when used in the United States.

    Regulatory environment fcc 2005
    Regulatory Environment FCC 2005

    • Commission concluded that

      • Technical measures that cognitive radios can employ will allow a reliable secondary use of licensed spectrum

      • Maintains

        • Availability of the spectrum

        • Rapid reversion to the licensee when needed

      • Saw no need to adopt any particular technical model for interruptible spectrum leasing

    Defense advanced research projects agency darpa
    Defense Advanced Research Projects Agency (DARPA)

    • Working on developing new technologies

      • Allow multiple radio systems to share the spectrum through adaptive mechanisms

    • NeXt Generation communications (XG) program

      • Identify behaviors versus detailed descriptions

        • Dynamically align rules with technologies for future radio systems


    • NeXt Generation communications (XG) program concepts (continued)

      • Abstract behaviors, protocols, and a policy language

      • Flexibility, long-term impact, and the need for regulatory approval

    Us army
    US Army

    • “Adaptive Spectrum Exploitation” (ASE)

    • Real-time spectrum management in the battlefield

      • “Tactical battlefield spectrum management”

      • Importance of spectrum planning

      • Dynamic apportionment

      • Dynamic interference resolution

    Spectrum agile radio salient features
    Spectrum Agile RadioSalient Features

    • Rules for radios as opposed to rules for services/applications

      • Radio regulators will continue to decide policy that specify behaviors of these radios

    • Spectrum sharing, interference management, and coordination between users, based on radio environment awareness

    • Real-time measurements, dissemination and opportunity identification

    Spectrum agile radio salient features1
    Spectrum Agile RadioSalient Features

    • Awareness of primary and secondary usage

      • Radio behaviors influenced by evolving policies

    • Policies set by regulators

    • Policies for wireless network management

      • Examples:

        • For U-NII bands, using etiquette as discussed in Wi-Fi

        • For hospitals

    Ieee lan man standards series
    IEEELAN/MAN Standards Series

    • Local Area Network standards

    • Metropolitan Area Network standards

    • Task Groups (TGs) to develop extensions

      • IEEE 1900 Next Generation Radio Standards

      • IEEE 802.22 Wireless Regional Area Networks

      • IEEE 802.11 Wireless Local Area Networks

        • 802.11h Spectrum Managed 802.11a

        • 802.11k Physical measurement of wireless energy

    Ieee 1900 next generation radio standards
    IEEE 1900 Next Generation Radio Standards

    • Established in the first quarter 2005

      • IEEE Communications Society (ComSoc)

      • IEEE Electromagnetic Compatibility (EMC) Society

    • Develop supporting standards

      • Next generation radio

      • Advanced spectrum management

    Ieee 802 22 wireless regional area networks
    IEEE 802.22 Wireless Regional Area Networks

    • Working Group on Wireless Regional Area Networks

    • Develop standard for spectrum agile radio-based air interface

      • License-exempt devices on a non-interfering basis

      • Spectrum allocated to TV Broadcast Service

    Ieee 802 11 wireless local area networks
    IEEE 802.11 Wireless Local Area Networks

    • Current wireless LAN standard

    • 802.11h Spectrum Managed 802.11a

    • 802.11k Physical measurement wireless energy

    Ieee 802 11h spectrum managed 802 11a
    IEEE 802.11h Spectrum Managed 802.11a

    • Resolve interference issues 802.11a in 5 GHz band

      • Military radar systems

      • Medical devices

      • Satellite communications

    • Transmit Power Control (TPC)

    • Dynamic Frequency Selection (DFS)

    Ieee 802 11h dynamic frequency selection dfs
    IEEE 802.11h Dynamic Frequency Selection (DFS)

    • Detects the presence/type of other devices on a channel

    • Requires quiet periods

    • Responds based upon type of device identified

      • When radar is identified

        • Devices MUST change channels

      • Will coexist with other 802.11 traffic

    Ieee 802 11k
    IEEE 802.11k

    “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications: Radio Resource Management of Wireless LANs”

    • Final approval of this amendment is targeted for January 2007

    • Defines measurement framework

    Ieee 802 11k where
    IEEE 802.11kWhere?

    • IEEE 802.11 wireless local area networks operate in the unlicensed

      • 2.4 GHz Industrial, Scientific and Medical (ISM )

      • 4.9 GHz (Japan)

      • 5 GHz Unlicensed National Information Infrastructure (UNII) bands

    Ieee 802 11k why
    IEEE 802.11kWhy?

    • Enable more accurate and efficient operation of Wireless LANs

    • Optimize radio environments

      • More devices can coexist

      • Reduce wireless network traffic congestion

    Ieee 802 11k how
    IEEE 802.11kHow?

    • Enhanced measurements and diagnostics

    • Medium sensing measurement requests and reports

    • Collects spectrum usage patterns

    Ieee 802 11k what
    IEEE 802.11kWhat?

    • Provides information about other radio systems on a channel

      • Could be 802.11 devices

      • Could be non-802.11 radiators such as a microwave

      • Can derive operational parameters for 802.11 stations

    Ieee 802 11k standards
    IEEE 802.11kStandards

    • Radio resource measurements not standardized

    • Standardized frame formats

      • Request for a specific measurement

        • One radio device to another

      • Report of such a measurement

        • Response to the request

    Ieee 802 11k what do you want to know
    IEEE 802.11k What do you want to know?

    • Is channel suitable for use?

    • Percent busy

    • Non-802.11 signals

    • Patterns of these Non-802.11 signals

    Ieee 802 11k clear channel assessment cca
    IEEE 802.11k Clear Channel Assessment (CCA)

    • Logical function found within physical layers

    • Determines the current state of use of wireless medium

    • Aids in contention avoidance

      • Process that determines if the device can transmit on the channel

    Ieee 802 11k clear channel assessment reports
    IEEE 802.11kClear Channel AssessmentReports

    • Channel Load Report

    • Noise Histogram Report

    • Medium Sensing Time Histogram Report

    Ieee 802 11k channel load report
    IEEE 802.11k Channel Load Report

    • Percentage of time the medium is busy during the measurement period

    Ieee 802 11k noise histogram report
    IEEE 802.11k Noise Histogram Report

    • Samples non-802.11 energy

    • Samples medium only when CCA indicates that no 802.11 signal is present

    • Reports noise and other non-802.11 signals

    Ieee 802 11k medium sensing time histogram
    IEEE 802.11k Medium Sensing Time Histogram

    • Histogram of busy and idle time observed

    • Assesses spectrum usage pattern of other radio devices

    • Shows pattern of medium usage so that medium can be shared

    Summary spectrum agile goals
    SummarySpectrum Agile Goals

    • Identify spectrum not used by primary users (‘spectrum white spaces’).

      • Transmit in white spaces with appropriate power levels

      • Do not cause interference to primary users

    • Detect the transmission of other secondary devices

      • Share some or all of the channels occupied by other secondaries

      • Reduce own blocking probability

    Identify spectrum hidden node problem
    Identify Spectrum Hidden Node Problem

    • Receivers are passive and their presence cannot be detected directly

    • Interference is caused at the receivers

    • Agile radios have to detect primary signal at thresholds that are under signal levels of primary devices

    • For example, directional antenna

    Identify spectrum power
    Identify Spectrum Power

    • Higher the transmit power employed by the spectrum agile radio

    • Further away that it must be able to detect a television transmitter

    Identify spectrum timeframe
    Identify Spectrum Timeframe

    • Sensing approaches must assess signal presence quickly

    • Wideband of spectrum must be sensed possibly one channel at a time

      • Different primary users

      • Different transmission characteristics

    Identify spectrum how
    Identify Spectrum How?

    • Energy Detection Approach

    • Feature Detection Approach

    Identify spectrum energy detection approach
    Identify Spectrum Energy Detection Approach

    • Wireless device measures RF energy in the channel

    • Sense the presence of a primary if energy is above threshold

    • Cannot arbitrarily lower the threshold

      • Result in non-detection because of Signal/Noise Ratio

    Energy detection approach disadvantages
    Energy Detection ApproachDisadvantages

    • Not be able to distinguish

      • Other secondary users

        • Share the medium

      • Primary users

        • Require movement to another channel

    Identify spectrum feature detection approach
    Identify Spectrum Feature Detection Approach

    • Used in the military to detect the presence of weak signals

    • Uses cyclostationary signal processing to detect the presence of primaries

      • Process exhibits cyclostationarity if its statistics vary periodically with time

    • Can be detected at very low signal-to-noise ratios (SNR)

    Identify spectrum implementation
    Identify Spectrum Implementation

    • Collocated Sensing Architecture

      • Single Radio Sensing Architecture

      • Dual Radio Sensing Architecture

    • Sensor Network Architecture

    • Agile Radio Policy

    Identify spectrum collocated sensing architectures
    Identify Spectrum Collocated Sensing Architectures

    • Sensing function and the data transmission collocated in a single device

    • Agile radio itself responsible for sensing spectrum usage

      • Single radio sensing architecture

      • Dual radio sensing architecture

    Single radio sensing architecture advantages
    Single Radio Sensing Architecture Advantages

    • Single radio

      • Both sensing and data transmission

    • Completely distributed

    • Simple to implement with less equipment

    • Longer battery life

    Single radio sensing architecture disadvantages
    Single Radio Sensing Architecture Disadvantages

    • “Lost transmit opportunity costs”

      • Radio has to reserve time for sensing

      • Decreasing time to transmit/receive data

    • Significant processing overhead

      • Obtain measurement results

      • Compare with past results

      • Estimate how channel is going to behave in the future

    Single radio sensing architecture disadvantages cont d
    Single Radio Sensing Architecture Disadvantages cont’d

    • Imposes limitation on MAC layer design

      • Collision - MAC has no means to determine cause

        • Transmission by another agile radio device

        • Channel error

        • Primary user

    • Does not overcome hidden node problem

    Dual radio sensing architecture advantages
    Dual Radio Sensing Architecture Advantages

    • Two radios

      • One is exclusively dedicated for sensing

      • Other is dedicated for data transmission

    • Removes “Lost transmit opportunity costs”

    Dual radio sensing architecture disadvantages
    Dual Radio Sensing Architecture Disadvantages

    • Additional complexity

    • Additional power constraints

    • Cost per device likely higher

    • Does not overcome hidden node problem

    Identify spectrum sensor network architecture
    Identify Spectrum Sensor Network Architecture

    • Two complementary networks

      • Sensing network

      • One or more operational networks

    Identify spectrum sensor network architecture1
    Identify Spectrum Sensor Network Architecture

    Sensor network architecture operational networks
    Sensor Network Architecture Operational Networks

    • Responsible for traditional data transmission

    • Opportunistic use of the spectrum

    • Accept the information about sensor network

      • Channel to use

      • When to use

      • How long to use

    Sensor network architecture sensor network
    Sensor Network Architecture Sensor Network

    • Separate network fully dedicated to spectrum sensing

    • Deployed in the desired target area

    • Communicate the results to sink node

    • Sink node makes the information available to operational networks

    Sensor network architecture advantages
    Sensor Network ArchitectureAdvantages

    • Numerous measurements made

      • Provide needed location diversity to identify multipath fading

    • No “Lost transmit opportunity costs”

    • Reduces power requirements for the Operational Network

    Sensor network architecture advantages1
    Sensor Network Architecture Advantages

    • Sensors

      • Inexpensive

      • Small form factor

      • Very energy efficient

    Sensor network architecture additional benefits
    Sensor Network ArchitectureAdditional Benefits

    • Can be designed to serve a wide and evolving range of purposes

      • Offer new measurement capabilities for older, regulated bands

    • Localizing illegal emitters

      • Spatial diversity allows this feature

    Identify spectrum agile radio policy
    Identify Spectrum Agile Radio Policy

    • FCC identifies licensed band with white space

    • FCC assigns policies for use of band

    • Policies published in machine-understandable form

    Agile radio policy advantages
    Agile Radio PolicyAdvantages

    • Autonomous spectrum management

    • Authority for radio regulation and spectrum management remains with Federal Communications Commission (FCC)

    • No need to sense the medium with additional equipment

    • No “Lost transmit opportunity costs”

    Agile radio policy distribution
    Agile Radio Policy Distribution

    • Policies are published in a machine-readable form

    • Policies are available for download from FCC servers

    • Agile radio devices obtain updates of policies from servers

    • Policies could be made available through memory devices such as flash cards

    Agile radio policy distribution cont d
    Agile Radio Policy Distribution cont’d

    • After update local information base

    • Disseminate updates to other agile radio devices

    • Devices that belong to different networks may coordinate sharing of radio resources with the help of spectrum etiquette

    Identify spectrum one proposed architecture
    Identify Spectrum One Proposed Architecture

    Opportunity identifier
    Opportunity Identifier

    • Determines opportunity bands

    • Senses available white space

    • Estimates white spaces duration

    • Passes results to Opportunity Manager

    Policy interaction
    Policy Interaction

    • Understands policies set by regulatory body

    • Interpretation passed to Opportunity Manager

    Opportunity manager
    Opportunity Manager

    • Core of this architecture

    • Requests measurements in target bands

    • Determines if particular band is an opportunity

    • Passes parameters to the flexible PHY

    • Responsible to map traffic to the MAC queue to these opportunities

    Flexible phy layer
    Flexible PHY Layer

    • Takes inputs from Opportunity Manager

    • Shapes waveforms so that they comply with transmission policies set by regulation

    Overall summary
    Overall Summary

    • More radio spectrum will be available to support new devices

    • New technologies will be required to make use of the spectrum

    • Lots of research opportunities