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Introduction and Overview

Introduction and Overview. Presentation by Dale N. Hatfield at the Radio Regulation Summit: Defining Out-of-Band Operating Rules Silicon Flatirons Center for Law, Technology, and Entrepreneurship Boulder September 8 - 9, 2009. Welcome and Introduction. Welcome Purpose of Summit

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Introduction and Overview

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  1. Introduction and Overview Presentation by Dale N. Hatfield at the Radio Regulation Summit: Defining Out-of-Band Operating Rules Silicon Flatirons Center for Law, Technology, and Entrepreneurship Boulder September 8 - 9, 2009

  2. Welcome and Introduction • Welcome • Purpose of Summit • Agenda • Review of Ground Rules • Introductions • Preliminary Remarks

  3. Outline • Welcome and Introduction • Types of Interference • Drawing Geographic Boundaries • Drawing Frequency Boundaries • Out of Band Interference • Drawing Time Boundaries • Introduction of Case Studies • 800 MHz Rebanding • AWS-3 • SDARS – WCS • Other Interference Cases

  4. Types of Interference (Potential “Trespass”) Source: IEEE P1900

  5. Drawing Geographic Boundaries • Cochannel Interference Interfering or Undesired Signal Desired Signal Transmitter B Both Transmitter A and Transmitter B are operating on the same channel causing cochannel interference if the geographic spacing is not sufficient Transmitter A

  6. Practical Radio Propagation Models Site General Model Drawing Geographic Boundaries

  7. Practical Radio Propagation Models Site Specific Model Drawing Geographic Boundaries

  8. Drawing Frequency Boundaries Output Signal Power • Adjacent Channel Interference Idealized “Perfect” Filter 100% Actual Filter 50% Frequency Lower Adjacent Channel Upper Adjacent Channel Desired Channel

  9. Drawing Frequency Boundaries Desired Signal • Adjacent Channel Interference – “Near-Far” Problem Undesired Signal on Adjacent Channel Transmitter B Transmitter A and Transmitter B are operating on channels adjacent in frequency; when the receiver is far from the desired transmitter and very close to the undesired transmitter, adjacent channel interference is exacerbated Transmitter A

  10. Drawing Frequency Boundaries • Transmitter Emission and Receiver Selectivity Characteristics Sample Transmitter Emission Mask Note that the FCC does not regulate receiver characteristics even though in some sense it is the receivers that “consume” spectrum; poor receiver front end selectivity, adjacent channel selectivity, intermodulation performance etc. can produce very inefficient use of the resource (See NOI in ET Docket No. 03-65, In the Matter of Interference Immunity Performance Specifications for Radio Receivers, Rel. 3/24/03)

  11. Band (“Front-end”) Filter) Channel (“IF”) Filter Frequency Lower Adjacent Band Desired Band Upper Adjacent Band Drawing Frequency Boundaries • Out of Band Interference • Filtering (Band vs. Channel Selection) Far Out of Band Interference Types: Intermodulation Desensitization/Overload

  12. Drawing Time Boundaries • Sharing Spectrum in Time Channel Occupancy Time Examples: AM Broadcasting – “Daytime Only Stations” Time Sharing of Radio Paging Channels (Historical) Time Division Multiple Access (TDMA) Dynamic Spectrum Assignment

  13. Observations Regarding AdjacentBand Interference Issues • Compared to Co-channel Interference, Adjacent Band (Both Near Band Edge and Far from Band Edge) Issues Are More Apt to be Problematical Because: • Interference can occur at any location within the geographic service area, not just at the edges • The actual or perceived risk or consequences of interference may be asymmetrical • The architectures and technologies may be vastly different • The number of players or stakeholders involved may be much larger and involve the general public directly

  14. Observations • Compared to Co-channel Interference, Adjacent Band Issues Are More Apt to be Problematical Because (Cont’d): • Providers in adjacent band are more likely to have very different perspectives, incentives and even cultures – e.g., public safety entities versus commercial entities • Receiver performance plays an especially important and complex role in adjacent channel/adjacent band interference issues and are not only not regulated, but sometimes outside the control of the service provider • Our case studies tend to confirm that hypothesis and that is reason for focusing special attention on the topic in this Summit

  15. Introduction of Case Studies • 800 MHz Rebanding • S-DARS – WCS Interference • AWS-3 Interference

  16. 800 MHz Rebanding - SMR (80 channels) INCLUDES NEXTEL - Business/SMR (50 channels) INCLUDES NEXTEL - Industrial/SMR (50 channels) INCLUDES NEXTEL - Public Safety (70 channels))* Up-Link 809.75 816 821 824 825 806 General Category INCLUDES NEXTEL B/ILT & SMALL NO. OF PUBLIC SAFETY Upper 200 SMR (NEXTEL) NPSPAC CELLULAR TV Broadcast Ch. 60-69 [7.5 MHz] [12.5 MHz] [10 MHz] [6 MHz] 851 854.75 861 866 869 870 Down-Link FCC Spectrum Allocation of 800 MHz Band * - Prior to Rebanding Source: APCO/Gurss Interference Concerns: Nextel Adjacent Channel Interference to Public Safety Intermodulation Interference (Nextel GC, Interleaved, Upper 200, & Cellular A Block)

  17. WCS S-DARS Sat. Ter. Sat. S-DARS – WCS Interference • S-DARS and WCS Spectrum AT WCS S-DARS Sat. Ter. Sat. 2332.5 MHz 2320 2345 2305 2360 2370 Interference Concerns S-DAR Terrestrial Tx (Repeaters)  WCS Receivers WCS Mobile Tx  S-DARS Mobile Rx WCS Base/Mobile Tx  AT Systems AT = Aeronautical Telemetry (2370 -2395 MHz)

  18. AWS-3 Interference Base Tx Mobile Rx Base Tx/Rx Mobile Tx/Rx • AWS-3 Interference to AWS-1 (Or Not) AWS-1 (FDD) AWS-3 (TDD) MSS 2110 2155 2180 Frequency (MHz) Paired with 1710-1755 Potential Interference Concerns: AWS-3 Mobile Tx AWS-1 Mobile Rx (Spillover/OBE) AWS-3 Mobile Tx AWS-1 Mobile Rx (Overload/Desensitization AWS-1 Base Tx  AWS-3 Base Rx

  19. Other Interference Cases • Mobile Satellite Service (MSS) Ancillary Terrestrial Component (ATC) Interference to GPS/GNSS MSS (Down) GPS MSS (Up) 1559 1575.42 GPS L1 Signal 1610 1626.5 1660.5 1525 Interference Concerns: MSS ATC Interference  GPS Rx

  20. Other Interference Cases • Military Radar Interference with 4.9 GHz Public Safety RA = Radio Astronomy Military Radar Public Safety Primary RA 4920 4940 5000 4990 Note: RA is also allocated 4940-4990 on a secondary basis Interference Concerns: Military Radar  Public Safety Systems

  21. 800 MHz Case Study • Potential Discussion Points • Could Public Safety’s interference rights have been defined adequately to allow cellularization of the SMR spectrum to take place or did the intermixing of the channels and basic incompatibilities between the two uses preclude such a transition as a practical matter? • If the former, would Coasian bargaining been successful between Nextel and the Public Safety community? • Not withstanding the fact that “zoning” (e.g., separating high power/high antenna site systems from low power, low antenna sites) reduces technical flexibility for the licensee (violates technical neutrality), is it required for pragmatic reasons?

  22. 800 MHz Case Study • Potential Discussion Points • FCC resolved the issue by: • Separating non-cellular (high-power, high elevation, noise-limited systems) from cellular (low-power, low elevation, interference limited systems) into different, discrete spectrum blocks • Prohibited the deployment of cellular systems in the non-cellular block • Established basis for resolving interference cases • Defined the environment in which protection would be provided to non-cellular licensees (as described above)

  23. 800 MHz Case Study • Potential Discussion Points (Cont’d) • Established basis for resolving interference cases (cont’d) • In that environment, if the desired signal is sufficient and if the radios (victim Rx) meet minimum performance requirements and the radios still receive unacceptable interference then that interference must be resolved • There is no protection or reduced protection if the desired signal is not sufficient or if the radios have reduced performance • Can this approach be generalized and used in other contexts to resolve out of band interference issues? • Challenges? Note: Portions of this section were based upon a conversation with Steve Sharkey of Motorola

  24. Contact Information Dale N. Hatfield Executive Director Silicon Flatirons Center for Law, Technology, and Entrepreneurship University of Colorado at Boulder 401 UCB - Office 404 Boulder, CO 80309 Direct Dial: 303-492-6648 Email: dale.hatfield@colorado.edu or dale.hatfield@ieee.org

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