Introduction and overview
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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

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 and Introduction

  • Welcome

  • Purpose of Summit

  • Agenda

  • Review of Ground Rules

  • Introductions

  • Preliminary Remarks


Outline

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


Types of interference potential trespass

Types of Interference (Potential “Trespass”)

Source: IEEE P1900


Drawing geographic boundaries

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


Drawing geographic boundaries1

Practical Radio Propagation Models

Site General Model

Drawing Geographic Boundaries


Drawing geographic boundaries2

Practical Radio Propagation Models

Site Specific Model

Drawing Geographic Boundaries


Drawing frequency boundaries

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


Drawing frequency boundaries1

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


Drawing frequency boundaries2

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)


Drawing frequency boundaries3

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


Drawing time boundaries

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


Observations regarding adjacent band interference issues

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


Observations

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


Introduction of case studies

Introduction of Case Studies

  • 800 MHz Rebanding

  • S-DARS – WCS Interference

  • AWS-3 Interference


800 mhz rebanding

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)


S dars wcs interference

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)


Aws 3 interference

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


Other interference cases

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


Other interference cases1

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


800 mhz case study

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?


800 mhz case study1

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)


800 mhz case study2

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


Contact information

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: [email protected] or

[email protected]


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