SFC Interference Summit - September 09wo

8/11/2019 SFC Interference Summit - September 09wo

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Introduction and Overview

Presentation by

Dale N. Hatfieldat the

Radio Regulation Summit:

Defining Out-of-Band Operating Rules

Silicon Flatirons Center for

Law, Technology, and Entrepreneurship

Boulder

September 8 - 9, 2009


2/24

Welcome and Introduction

Welcome

Purpose of Summit

Agenda

Review of Ground Rules

Introductions Preliminary Remarks


3/24

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

SDARSWCS

Other Interference Cases


4/24


In Band Out of Band

Cochannel Adjacent Channel Near Band Edge Far From Band Edge


(Potential Trespass)

Source: IEEE P1900


5/24


Desired Signal

Interfering or Undesired

Signal

Transmitter A

Transmitter B

Both Transmitter A and Transmitter B

are operating on the same channel causing

cochannel interference if the geographic

spacing is not sufficient

Cochannel Interference


6/24


Practical Radio Propagation Models

Site General Model


7/24


Practical Radio Propagation Models

Site Specific Model


8/24


Adjacent Channel Interference

Lower

Adjacent

Channel

Output Signal

Power

100%

50%

Upper

Adjacent

Channel

FrequencyDesiredChannel

Idealized Perfect Filter

Actual Filter


9/24


Undesired Signal on

Adjacent Channel

Desired Signal

Transmitter A

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

Adjacent Channel InterferenceNear-Far

Problem


10/24


Transmitter Emission and ReceiverSelectivity Characteristics

Sample Transmitter

Emission Mask

Note that the FCC does not regulate

receiver characteristics even thoughin some sense it is the receivers that

consume spectrum; poor receiver

front end selectivity, adjacent

channel selectivity, intermodulation

performance etc. can produce veryinefficient 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)


11/24

Drawing Frequency Boundaries Out of Band Interference

Filtering (Band vs. Channel Selection)

Frequency

Band (Front-end)

Filter)Channel (IF) Filter

Lower Adjacent

Band

Desired

Band

Upper Adjacent

Band

Far Out of Band Interference Types:

Intermodulation

Desensitization/Overload


12/24

Drawing Time Boundaries

Sharing Spectrum in Time

Time

Channel

Occupancy

Examples:AM BroadcastingDaytime Only Stations

Time Sharing of Radio Paging Channels (Historical)

Time Division Multiple Access (TDMA)

Dynamic Spectrum Assignment


13/24

Observations Regarding Adjacent

Band 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


14/24

Observations

Compared to Co-channel Interference, AdjacentBand Issues Are More Apt to be Problematical

Because (Contd):

Providers in adjacent band are more likely to have very

different perspectives, incentives and even culturese.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, butsometimes 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


15/24

Introduction of Case Studies

800 MHz Rebanding

S-DARSWCS Interference

AWS-3 Interference


16/24

FCC Spectrum Allocation

of 800 MHz Band * - Prior to Rebanding

TV

Broadcast

Ch. 60-69

General Category

INCLUDES NEXTELB/ILT & SMALL

NO. OF PUBLIC

SAFETY

Upper200 SMR

(NEXTEL)

806 825816

851 870861 866

809.75

854.75

NPSPAC

821 824

869

- SMR (80 channels) INCLUDES NEXTEL- Business/SMR (50 channels) INCLUDES NEXTEL- Industrial/SMR (50 channels) INCLUDES NEXTEL

- Public Safety (70 channels))*

Up-Link

Down-Link

[7.5 MHz] [12.5 MHz] [10 MHz] [6 MHz]

CELLULAR

Source: APCO/Gurss

800 MHz Rebanding

Interference Concerns:

Nextel Adjacent Channel Interference to Public Safety

Intermodulation Interference

(Nextel GC, Interleaved, Upper 200, & Cellular A Block)


17/24

S-DARSWCS Interference

S-DARS and WCS Spectrum

WCSSat. Ter. Sat.

S-DARS WCSSat.Ter.Sat.

S-DARS

2305 2320 2345 23602332.5 MHz

Interference Concerns

S-DAR Terrestrial Tx (Repeaters)WCS Receivers

WCS Mobile TxS-DARS Mobile RxWCS Base/Mobile TxAT Systems

AT

AT = Aeronautical Telemetry (2370 -2395 MHz)

2370


18/24

AWS-3 Interference

AWS-3 Interference to AWS-1 (Or Not)

AWS-1 (FDD) AWS-3 (TDD) MSS

Frequency (MHz)2110 2155 2180

Paired with

1710-1755

Base Tx

Mobile Rx

Base Tx/Rx

Mobile Tx/Rx

Potential Interference Concerns:

AWS-3 Mobile TxAWS-1 Mobile Rx (Spillover/OBE)

AWS-3 Mobile TxAWS-1 Mobile Rx (Overload/Desensitization

AWS-1 Base TxAWS-3 Base Rx


19/24


Mobile Satellite Service (MSS) AncillaryTerrestrial Component (ATC) Interference

to GPS/GNSS

MSS (Down) GPS MSS (Up)

1525 1559 1610 1626.5 1660.51575.42

GPS L1 Signal


MSS ATC InterferenceGPS Rx


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Military Radar Interference with 4.9 GHz

Public Safety

Military Radar Public Safety Primary RA

4920 4940 4990 5000


Military RadarPublic Safety Systems

RA = Radio Astronomy

Note: RA is also allocated 4940-4990 on a secondary basis


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800 MHz Case Study

Potential Discussion Points Could Public Safetys 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., separatinghigh 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?


22/24

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 beprovided to non-cellular licensees (as described above)


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800 MHz Case Study

Potential Discussion Points (Contd) Established basis for resolving interference cases(contd)

In that environment, ifthe desired signal is sufficient and ifthe

radios (victim Rx) meet minimum performance requirements

and the radios still receive unacceptable interference then thatinterference 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


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Contact Information

Dale N. HatfieldExecutive Director

Silicon Flatirons Center

for Law, Technology, and Entrepreneurship

University of Colorado at Boulder401 UCB - Office 404

Boulder, CO 80309Direct Dial: 303-492-6648

Email: [email protected]@ieee.org
mailto:[email protected]:[email protected]:[email protected]:[email protected]

Documents

SFC Interference Summit - September 09wo