Transcript Recent Developments in Telecommunications Technology

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
Agenda
Review of Ground Rules
Introductions
Preliminary Remarks
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
In Band
Cochannel
Out of Band
Adjacent Channel
Near Band Edge
Source: IEEE P1900
Far From Band Edge
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 Boundaries
• Practical Radio Propagation Models
– Site General Model
Drawing Geographic Boundaries
• Practical Radio Propagation Models
– Site Specific Model
Drawing Frequency Boundaries
• Adjacent Channel Interference
Output Signal
Power
Idealized “Perfect” Filter
100%
Actual Filter
50%
Lower
Adjacent
Channel
Desired
Channel
Upper
Adjacent
Channel
Frequency
Drawing Frequency Boundaries
• Adjacent Channel Interference – “Near-Far”
Problem
Desired Signal
Undesired Signal on
Adjacent Channel
Transmitter B
Transmitter A
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
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 Boundaries
• Out of Band Interference
– Filtering (Band vs. Channel Selection)
Band (“Front-end”)
Filter)
Channel (“IF”) Filter
Frequency
Lower Adjacent
Band
Desired
Band
Far Out of Band Interference Types:
Intermodulation
Desensitization/Overload
Upper Adjacent
Band
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
• 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
• 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
• 800 MHz Rebanding
• S-DARS – WCS Interference
• AWS-3 Interference
800 MHz Rebanding
FCC Spectrum Allocation
of 800 MHz Band * - Prior to Rebanding
- SMR (80 channels) INCLUDES NEXTEL
- Business/SMR (50 channels) INCLUDES NEXTEL
- Industrial/SMR (50 channels) INCLUDES
- Public Safety (70 channels))*
Up-Link
809.75
806
NEXTEL
816
General Category
TV
Broadcast
Ch. 60-69
821
Upper 200 SMR
(NEXTEL)
INCLUDES NEXTEL
824
NPSPAC
825
CELLULAR
B/ILT & SMALL
NO. OF PUBLIC
SAFETY
[7.5 MHz]
851
[12.5 MHz]
854.75
[10 MHz]
861
[6 MHz]
866
869
870
Down-Link
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
• S-DARS and WCS Spectrum
WCS
2305
S-DARS
S-DARS
Sat.
2320
Ter.
Sat.
Sat.
2332.5
Ter.
Sat.
WCS
2345
AT
2360
2370 MHz
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 to AWS-1 (Or Not)
Base Tx
Mobile Rx
AWS-1 (FDD)
2110
Base Tx/Rx
Mobile Tx/Rx
AWS-3 (TDD) MSS
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
• Mobile Satellite Service (MSS) Ancillary
Terrestrial Component (ATC) Interference
to GPS/GNSS
MSS (Down)
1525
1559
GPS
1575.42
GPS L1 Signal
Interference Concerns:
MSS ATC Interference  GPS Rx
MSS (Up)
1610
1626.5
1660.5
Other Interference Cases
• Military Radar Interference with 4.9 GHz
Public Safety
RA = Radio Astronomy
Military Radar
4920
Public Safety Primary
4940
Note: RA is also allocated 4940-4990 on a secondary basis
Interference Concerns:
Military Radar  Public Safety Systems
RA
4990
5000
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 Study
• Potential Discussion Points
– FCC resolved the issue by:
• Separating non-cellular (high-power, high elevation, noiselimited systems) from cellular (low-power, low elevation,
interference limited systems) into different, discrete spectrum
blocks
• Prohibited the deployment of cellular systems in the noncellular 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 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
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]