Presentation is loading. Please wait.

Presentation is loading. Please wait.

Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) 1 Chapter 2 Radio.

Similar presentations


Presentation on theme: "Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) 1 Chapter 2 Radio."— Presentation transcript:

1 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) 1 Chapter 2 Radio Frequency Spectrum and Regulation

2 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) The Basics An understanding of the actual physics behind the layers of interactions in cognitive radio environments Provides a valuable basis for understanding the rest of the topic!

3 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Characteristics of Electromagnetic Waves Radiate (stone in a pond) / light bulb Decrease in intensity with distance (R 2 Rule) from point of origin Can travel in straight line (lens / laser) Can be Reflected, Refracted, Diffused, Scattered and Absorbed

4 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Electromagnetic Spectrum 4 Photograph of the output of a prism on a table

5 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Propagation Received Power is inversely Proportional to Distance from The Transmitter (radius) Squared – the R 2 Rule!

6 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Reflection / Refraction Velocity 1 Reflection Refraction Interface Incident Ray i i r Velocity 2 Refraction r

7 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Diffraction - Absorption - Scattering Incident

8 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Characteristics of Electromagnetic Waves Radiate (stone in a pond) Can travel in straight line (lens / laser) Decrease in Intensity with distance from point of origin Can be Reflected, Refracted, Diffused, Scattered, and Absorbed Even more exciting, waves can and do all these things at the same time and based on mobility, dynamically change as well!

9 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Reflection / Refraction Velocity 1 Reflection Interface Incident Ray i i r Velocity 2 Refraction Velocity 2 r Velocity 1 Refraction Reflection Incident Ray Interference Source

10 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Electromagnetic spectrum Our Focus Visible Light X-rays Ultraviolet Infrared Microwaves Radio ,000 Wavelength (in cm) High Frequency Short Wavelength Low Frequency Long Wavelength

11 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Wavelength = Speed of Light / Frequency – or – = c / f for WiFi – b/g, f =~ 2.4 GHz and c = ~300,000 km / sec, therefore, =~300,000 / 2,400,000 = 12.5 cm (~ 4.9) For low band cellular, f = 900 MHz – therefore 300,000 / 900,000 = 33.3 cm (~13) Frequency and Wavelengths

12 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009)

13 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) 13

14 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Cognitive Radio Challenges Interference! Co-existence Interoperability Complexity International Standards & Regulations Power …

15 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Regulatory Issues for Cognitive Access Should a Regulator Allow Cognitive Access? Deciding not to allow it (and hence do nothing). Enabling existing license holders to allow cognitive access into their own bands if they chose to. Licensing cognitive access to particular bands. 15

16 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Regulatory Issues for Cognitive Access Exempting cognitive equipment from the need for licensing with appropriate restrictions on when, where and how they might operate. 16

17 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Regulatory Issues for Cognitive Access How to Determine the Rules of Entry If the regulator has decided to allow cognitive access to a particular band, the next step in to set the rules of entry. Rules ensure a very low probability of interference to the incumbent users of the band while at the same time placing the minimum possible restrictions on the cognitive device 17

18 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Regulatory Issues for Cognitive Access The incumbents will be seeking the maximum level of protection Will seek out situations where the hidden node problem or other signal modification issues are most extreme. Even setting an appropriate level of probability of interference occurring can be fraught with difficulties. 18

19 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Regulatory Issues for Cognitive Access Even setting an appropriate level of probability of interference occurring can be fraught with difficulties Many other rules are also needed including: Maximum inband power Out-of-band power limits Bandwidth Transmit power control Sensing periodicity 19

20 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Regulatory Issues for Cognitive Access Regulatory Implications of Different Methods of Cognition Geographical Databases Access to a database listing the frequencies allowed to secondary use at each location. Beacon Reception Transmission of a signal from some appropriate infrastructure providing information on which frequencies are available for cognitive use 20

21 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Regulatory Issues for Cognitive Access Geographical Databases To what accuracy should the device know its location? Who will maintain the database? What availability is needed for the database? How will devices download updated versions of the database? What about dynamic use of spectrum? 21

22 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Regulatory Issues for Cognitive Access Beacon Reception Who provides the beacon signal? How is the information the beacon is transmitting kept up to date, especially where the licensed services are changing rapidly? What spectrum is used for the beacon? What technical parameters and protocols are used by the beacon transmitter? 22

23 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Regulatory Issues for Cognitive Access Regulatory Developments to Date Most notably in November 2008 the FCC published its Report and Order enabling cognitive access in the white space in the TV broadcast spectrum. In July 2009 Ofcom published a statement on Licence-exempting Cognitive Devices Using Interleaved Spectrum 23

24 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Regulatory Issues for Cognitive Access The FCC concluded that sensing alone was insufficiently proven for cognitive access. Sensing alone would result in an unacceptable risk of interference. Geographical databases were also required. 24

25 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Spectrum Occupancy Studies 25 Radio Car – circa 1927 (photo courtesy of the Institute for Telecommunications Science (ITS), NTIA, U.S. Dept. of Commerce)

26 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Spectrum Occupancy Studies 26 WPI team prepare for an RF spectrum measurement sweep in downtown Rochester, NY.

27 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Spectrum Occupancy Studies 27 A map of the forty eight locations close to I-90 between Boston, MA and Blandfield, MA over which spectrum measurements were collected in June 2009

28 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Snapshot Studies 28

29 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Spectrum Observatories 29 IITs Spectrum Observatory antenna array

30 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Spectrum Observatories 30 SQUIRRELWeb spectrum measurement interface at WPI

31 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) TV Spectrum Utilization 31 Spectrogram of TV channels taken in Chicago April 2008

32 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Cellular Spectrum Utilization 32 Spectrogram of 800 MHz cellular band in Chicago taken 1724 April 2008

33 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Paging Spectrum Utilization 33 Wireless spectrum of MHz in Rochester, NY on 19 June 2008.

34 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Chapter 2 Summary Nature of the electromagnetic spectrum with specific focus on that portion of the spectrum most useful for radio networks and communications systems Cursory review of the early use of this spectrum has been presented 34

35 Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) Chapter 2 Summary Rise in national and international regulatory bodies focused on both the allocation of the spectrum and in defining the acceptable parameters for its use Emerging unlicensed approaches to the use of the spectrum have been examined Cognitive access approach to spectrum utilization 35


Download ppt "Cognitive Radio Communications and Networks: Principles and Practice By A. M. Wyglinski, M. Nekovee, Y. T. Hou (Elsevier, December 2009) 1 Chapter 2 Radio."

Similar presentations


Ads by Google