Cognitive Radio and Efficient Spectrum Management

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Cognitive Radio and Efficient Spectrum
Management by Dr. Ashok Chandra Joint Wireless
Adviser Ministry of Communications Information
Technology, Government of India, New Delhi Email
drashokchandra_at_gmail.com
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• Outline
• Backdrop
• Cognitive Radio
• ITU Guidelines/Recommendations on Cognitive Radio
• Effect of Radio Noise
• Cognitive Radio Solution to Spectrum Monitoring
• Study Conducted so far
• Key Research Challenges

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4th Generation Convergence is really what 4G
is all about B3G Pers 4G Where B3G is
defined as the integration of existing systems to
interwork with each other and with a new
interface. Pers stands for Personalization
The future generation gadgets have to share a
finite and increasingly crowded amount of radio
spectrum.
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Definition of 4 G III

• 4G is defined as a completely new fully IP-based
  integrated system of systems and network of
  networks achieved after convergence of wired and
  wireless networks as well as computers, consumer
  electronics, and communication technology and
  several other convergences that will be capable
  to provide 100 Mbps and 01 Gbps, respectively in
  outdoor and indoor environments, with end-to-end
  QoS, high security and low power consumption,
  offering any kind of services at any time as per
  user requirements, anywhere with seamless
  interoperability, always on, affordable cost,
  one billing and fully personalized.

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• Radio Frequency Spectrum
• The increased demand for spectrum and use of
  traditional method of management have strained
  the spectrum management regime.
• The ultimate aim is to increase spectrum
  efficiency through the use of more flexible
  spectrum allocation and radio resource management
  schemes.
• The solution lies with cognitive radios (CR),
  devices that figure out which frequencies are
  quiet and pick one or more over which to transmit
  and receive data.
• Concept of CR can be compared with the scheme to
  a driver's reacting to what one sees other
  drivers doing. In a traffic lane that is heavy,
  maybe it's time for me to shift to another lane
  that is not so busy. When shifting lanes,
  however, a driver needs to follow rules that
  prevent her from bumping into others.

Radio Frequency Spectrum
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Cognitive Radio

• The idea of Cognitive radio was first presented
  officially in an article by Mitola III.
• It was a novel approach in wireless
  communications that Mitola later described as the
  point in which wireless personal digital
  assistant (PDAs) and the related networks are
  sufficiently computationally intelligent about
  radio resources.
• Regulatory bodies in various countries found
  that most of the Radio frequency spectrum was
  inefficiently utilized, for example, cellular
  network bands are overloaded in most parts of the
  world, but amateur radio and paging frequencies
  are not.
• The fixed spectrum allocation prevents rarely
  used frequencies from being used by unlicensed
  users, even when their transmissions would not
  interfere at all with the assigned service.

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• Certain types of cognitive radio can be
  distinguished as
• Full Cognitive Radio, in which every possible
  parameter observable by a wireless node or
  network is taken into account.
• Spectrum Sensing Cognitive Radio in which only
  the radio frequency spectrum is considered.
• Cognitive radio itself is a methodology for
  opportunistic utilization of uncultivated
  spectrum. Depending on the parts of the spectrum
  available for cognitive radio, it can be
  distinguished
• Licensed Band Cognitive Radio in which cognitive
  radio is capable of using bands assigned to
  licensed users, apart from unlicensed bands, such
  as ISM band. One such system is described in the
  IEEE 802.15 Task Group.
• Unlicensed Band Cognitive Radio which can only
  utilize unlicensed parts of radio frequency
  spectrum. An example of Unlicensed Band Cognitive
  Radio is IEEE 802.19.
• Each class has unique challenges to ensure
  successful operation.

Cognitive Radio
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• Certain smart radio capabilities are employed to
  some extent today in applications such as
  commercia mobile wireless services and wireless
  lopcal area network (WLANs).
• The long term vision of cognitive radio
  technology is one in which handsets would
  automatically make use of underutilised spectrum
  across a broad frequency range, allowing the high
  bandwidth requirements of the future set out in
  our vision to be realised.

Cognitive Radio
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• A cognitive radio unit requires to know how
  radiated RF power at its location varies with
  distance along the ground, among obstructions and
  up in the air. Cognitive radios instead sense the
  entire local RF environment of low, medium and
  high bands, mapping its features as a function of
  space, time and frequency propagation.
• The development of spectrum-sensing cognitive
  radio will require the design of high-quality
  sensor devices and practical algorithms for
  exchanging spectrum-monitoring data between
  cooperating communications nodes.
• It is hoped that by using underutilized spectrum
  cognitive radio will provide a 10 times spectrum
  capacity improvement. Potential users of
  cognitive adhoc wireless LAN technologies include
  public safety, military, homeland defense, and
  commercial wireless organizations.
• There are real challenges for cognitive radio to
  overcome, especially when it comes to ensuring
  on-going channel and radio sensing and minimum
  network disruption in an incumbent system is
  detected.

Cognitive Radio
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ITU Recommendations on Cognitive Radio

• 
  
  QUESTION ITU-R 241/8
• Cognitive radio systems in the mobile service
• The ITU Radio communication Assembly,
• considering
• that the use of mobile radio systems is growing
  at a rapid rate globally
• that more efficient use of spectrum is essential
  to the continued growth of such systems
• c) that cognitive radio systems may facilitate
  the more efficient use of spectrum in mobile
  radio systems

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ITU continued

• d) that cognitive radio systems may offer
  functional and operational versatility and
  flexibility in mobile radio systems
• that considerable research and development is
  being carried out on cognitive radio systems and
  related radio technologies
• that the implementation of cognitive radio
  systems may include technical and regulatory
  issues, and it is beneficial to identify the
  technical and operational characteristics
• g) that Reports and/or Recommendations on
  cognitive radio systems would be complementary to
  other ITU-R Recommendations on mobile radio
  systems

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ITU continued

• Noting that there are network aspects related to
  the control of cognitive
• radio systems, decides that the following
  Question should be studied
• What is the ITU definition of cognitive radio
  systems?
• What are the closely related radio technologies
  (e.g. smart radio, reconfigurable radio,
  policy-defined adaptive radio and their
  associated control mechanisms) and their
  functionalities that may be a part of cognitive
  radio systems?
• What key technical characteristics, requirements,
  performance and benefits are associated with the
  implementation of cognitive radio systems?
• What are the potential applications of cognitive
  radio systems and their impact on spectrum
  management?
• What are the operational implications (including
  privacy and authentication) of cognitive radio
  systems?

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ITU continued

• What are the cognitive capabilities that could
  facilitate coexistence with existing systems in
  the mobile service and in other
  radiocommunication services, such as broadcast,
  mobile satellite or fixed?
• What spectrum-sharing techniques can be used to
  implement cognitive radio systems to ensure
  coexistence with other users?
• How can cognitive radio systems promote the
  efficient use of radio resources?
• further decides
• that the results of the above studies should be
  included in one or more Recommendations and/or
  Reports
• that the above studies should be completed by the
  year 2010.
• This Question should be brought to the attention
  of Study Groups 1, 4, 6
• and 9.

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• Working Party 8A of the ITU in a Draft New Report
  on Software Defined Radio (SDR) tentatively
  defines cognitive radio as A radio or system
  that senses, and is aware of its operational
  environment and can be trained to dynamically and
  autonomously adjust its operating parameters
  accordingly.
• At ITU World Radio Conference (WRC)-2003, the
  regulatory community agreed on a method for 5 GHz
  spectrum sharing of radar and wireless access
  systems.

ITU continued
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• Effect of Radio Noise
• The ideal of cognitive radio etiquette is
  complicated by the variation over time of the
  aggregate interference produced by the
  environment, which includes that created by
  natural electrical noise (from lightning),
  electrical power generators, electric motors,
  automobile ignition systems and radio
  transmitters. The effects of these RF sources
  change over time
• At night, for example, few elevators are active,
  so their electric drive motors produce little
  noise, but during rush hour that noise grows.

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Cognitive Radio Solution to Spectrum Monitoring

• There are real challenges for cognitive radio to
  overcome, especially when it comes to ensuring
  on-going channel and radio sensing and minimum
  network disruption in an incumbent system is
  detected.
• Cognitive radio itself is a methodology for
  opportunistic utilization of uncultivated
  spectrum and can be categorized into two broad
  classes
• Unlicensed cognitive radios operating in the
  unlicensed bands and
• Unlicensed cognitive radios operating in the
  licensed bands. Each class has unique challenges
  to ensure successful operation

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Solution to Spectrum Monitoring

• Process of Spectrum Monitoring
• Three key concepts of spectrum monitoring
• Validating information on legitimate users
• 2. Evaluating real levels of usage of the
  spectrum
• 3. Identifying areas for further use, sharing or
  reallocation

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• Classes of Spectrum Monitoring
• Monitoring band occupancy
• At the allocation stage when existing band
  undergoes a change of use or when a new service
  is introduced. To ensure that the old services
  have vacated the band or that any sharing
  arrangements are in fact working in practice.
• Monitoring channel occupancy
• This will confirm or detect the level of use of
  frequency assignments in particular channels.
• Interference investigation
• Dealing with the complaints regarding
  interference.

Solution to Spectrum Monitoring
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• Classes of Spectrum Monitoring
• Compliance (routine) monitoring
• Routine monitoring to ensure or confirm that new
  users meet license conditions. Such a random and
  selective inspections are particularly effective
  in terms of improving and maintaining compliance
  levels.
• International monitoring
• Deals with the discovering and resolving the
  international interference sources.

Solution to Spectrum Monitoring
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• What is being monitored?
• Fixed monitoring and HF direction finding
• (2) VHF/UHF mobile and remote monitoring
• (3) AM, FM, television, and microwave monitoring
• (4) Satellite monitoring
• Spectrum Monitoring Issues
• The two main issues of spectrum monitoring are
• Regulatory issues Monitoring the compliance with
  the conditions in the license
• Interference issues Resolving harmful
  interference cases

Solution to Spectrum Monitoring
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Studies Conducted so far

• As per WRC-03, it was agreed on a method for 5
  GHz spectrum sharing of radar and wireless access
  systems. The basis for the sharing was agreement
  on the use of Dynamic Frequency Selection in
  5230-5350 MHz and 5470-5725 MHz.
• The Canada's Communications Research Centre (CRC)
  the Microwave-Light Organized Network (MILTON)
  is primarily designed to use 5 GHz license-exempt
  spectrum. By using aggressive frequency reuse,
  it's expected that a MILTON can effectively deal
  with the interference that can be expected when
  using 5 GHz.
• The demonstrations will exercise prototypes in
  spectrum bands between 30 MHz and 2 GHz.
• Internet in remote areas began propagation
  studies of the possible use of the 5 GHz
  unlicensed spectrum for cognitive radio.
• More Unlicensed Spectrum Allocations Unlicensed
  spectrum is ideal for cognitive radio.

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• Key Research Challenges
• Study on deciding which bands would be available
  for initial CR trials.
• Develop cognitive radio algorithms to enable
  co-existence between IEEE 802.11b and 802.16a
  networks in the same unlicensed band.
• Develop two wireless systems share radio
  resources in frequency, space and time, and
  coordination methods to be used to reduce the
  mutual interference.
• The effect of interference produced by the
  man-made/natural environment.
• Study on defining "harmful interference" within
  the authorized CR bands

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• Study to know how radiated RF power at its
  location varies with distance along the ground,
  among obstructions and up in the air.
• Develop practical algorithms for the
  spectrum-sensing cognitive radio,, for exchanging
  spectrum-monitoring data between cooperating
  communications nodes.
• Mapping of the local RF environment of low,
  medium and high bands, mapping as a function of
  space, time and frequency propagation.
• Study on the complex multipath components--thereby
  accounting for reflections of signals from
  objects such as buildings and vehicles.
• Study on defining the rights of the licensed
  spectrum band users where CR technology is
  authorized.

Key Research Challenges
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• Deciding which bands would be available for
  initial CR trials, through equitable sharing
  studies conducted cooperatively between industry
  and government agencies.
• Confirming the results of such sharing studies
  through field trials would, open up other CR
  bands as the technology proves effective, and
  further sharing studies and field trials would
  confirm the CR ability to coexist in those other
  bands.
• Defining the rights of the licensed spectrum band
  users where CR technology is authorized.
  Certainly, licensed users should be protected
  from CR interference (largely a technical issue).
  
• CR to operate on a truly non-interfering basis.

Key Research Challenges
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Thank you