Achieving Predictable Reliability
Why primary use licenses are superior to secondary licenses for reliable
AMI utility transmissions
WP-R-FLX-0000-0812-01-A
White Paper
INTRODUCTION
Numerous considerations are in play for utility officials when choosing a data communication system. It is
a substantial investment, with the eyes of regulatory agencies and customers watching intently. Among the
smartest of decisions an official can make during the selection process is to minimize transmission risk and
increase credibility by achieving predictable reliability. To do so, it is necessary to secure a guaranteed position from which to operate within America’s finite radio spectrum bandwidth. Primary use licenses supply
that position, with protection from the Federal Communications Commission (FCC), as compared to the
doubts, restrictions and uncertainties associated with secondary use licenses.
This white paper illustrates why the primary use license is a superior asset in the AMI metering industry
over its secondary use counterpart. It also illuminates an unfortunate marketing ploy by secondary license
holders: Describing transmissions as being sent through a “licensed” spectrum. While technically accurate,
the entire truth is that every major vendor has a secondary use license, except Sensus, which operates on a
primary use system that does not contain the constraints of secondary spectrums.
The Freedom of Operations for Primary Use License Holders
The advantages of transmitting through a primary use system are
many, and comparisons between primary and secondary systems
can be delineated clearly and without hesitation. However, the
single most important benefit rests in the amount of control the
utility has access to. In a primary use system, the utility has 100
percent control of its transmission environment - a monopoly protected and guaranteed by the FCC’s Universal Licensing System.
Sensus operates from a nationwide primary use channel at the
900 MHz level, which covers 100 percent of the United States’
geographical footprint. This gives Sensus customers unlimited
access to the assets that lie within the FCC’s primary use spectrum
at this level.
Under FCC rules, if a primary use license holder encounters an
interfering transmission that raises the noise floor by just one
decibel, the primary use holder has the legal right to demand the
secondary use holder stop transmitting. Failure to comply brings
the FCC into the situation, with results ranging from $10,000 per
day fines for each day of interference to jail time for the operator.
The Perils of Operations for Secondary Use License Holders
“Secondary users hold a risky position in their service operations
since they may not have direct control over the availability of radio
spectrum, quality of service, and coverage expectation. This may
make it difficult for the secondary users to control the quality
of service they provide to their clients,” as stated by researchers
Arnon Tonmukayakul and Martin B.H. Weiss of the University
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of Pittsburgh in a white paper entitled, Secondary Use of Radio
Spectrum: A Feasibility Analysis.
Utilities who work via secondary use systems are at the mercy of
primary users. Secondary use utilities must negotiate with the
primary spectrum holder for how much, and when, their transmissions may be sent and received.
William Lehr of the Massachusetts Institute of Technology also
addressed the interplay of secondary versus primary use license
transmissions. Lehr explained that secondary users are “allowed to
transmit when the primary use licensee is not using the spectrum.
This could be defined in the spatial domain (e.g., rural areas
that a broadcaster is not currently serving) or time domain (e.g.,
when the primary licensee is not transmitting using “listen-before
talking” technology). The unlicensed overlay devices would use
appropriate sensing technology to determine when the spectrum
is free to transmit. With licensed spectrum, the licensee with the
exclusive right clearly has a primary claim to the spectrum.”
Another issue for vendors with secondary use licenses is the additional hierarchy of use within the secondary spectrum itself.
Operating at the 450-470 MHz level, secondary use license holders who deploy voice transmissions are given preference over data
and telemetry users. Voice license holders, such as fire, police and
emergency services - or even taxi and pizza companies - have a
limited transmission radius to transmit in segments of 12.5 kHz.
Add to that community the data and telemetry transmissions of a
utility. Under FCC law, the pizza company or taxi driver has the
legal grounds to have the utility stop transmissions that interfere
with their voice signals.
Further, a utility’s transmission at the secondary use license level,
ent even less power to rely on for credible transmission of system
regardless of the FCC-assigned channel, is subject to spectral mass
data. Second, for those opting for the highest available power of
requirements. Thus, the utility must accept and work with noise
430-512 MHz, the FCC mandates will force extra operating costs
floor interference from up to five channels next to them - noise
to be incurred to stay in FCC compliance - financial burdens that
that naturally “seeps” across channel boundaries in the secondwill add to the overall cost.
ary use license world simply by other transmitters keying their
Further, the American economy is tipping scales toward more retmicrophones. In the effort to collect meter readings, this interferrofitting of utility systems instead of implementing new designs.
ence could play havoc with accuracy and reliable transmissions, as
Retrofitting to the specification
well as interrupting attempts
of these new FCC mandates
at collecting real-time data or
Potential Users of Spectrum
promises to be yet another costly
operating a SCADA system.
undertaking.
Primary License
Secondary License
Secondary use license holders
For those going to a 450 MHz
Voice, Data and Telemetry
are combatting this scenario
system, the former 12.5 kHz they
Sensus
Voice
by transmitting sometimes
used for transmissions will be rein the dead of night, with the
• Fire
duced to a certain bit rate onto a
hope of minimizing vulner• Police
6.25 kHz-spaced channel under
ability and of achieving a
• Emergency Services
the new FCC plan. Vendors will
higher likelihood of being
• Taxi dispatch
need to resupply equipment and
accurate when others aren’t
• Pizza / Restaurant Delivery
reprogram endpoints, collectors,
broadcasting. This strategy
walk-by units and drive-by units.
may be acceptable for an
Secondary use license holders
Data
AMR system but, as the
will also be adversely impacted
• AMI Vendors
market moves to AMI and
in their ability to buy upgrades
the Smart Grid, this plan will
and replacements now, knoweventually fail.
Secondary license holders who use voice transmission are given
ing that they won’t be able to
preference over data and transmission users
purchase that same equipment in
The FCC’s Narrowbanding
the future.
Mandates
The sheer amount of power in primary use spectrums is markedly
above the capacity available within a secondary use spectrum. This
deficit has caught the attention of the FCC, which placed mandates to control how secondary users can work on narrowband
channels and how they can transmit on lower power. The goal of
narrowbanding is to open more efficient use of the spectrum.
“Narrowband” refers to a low bandwidth in VHF and UHF radio
and low-speed Internet connections, where a limited amount of
data can be transmitted because of the small range of the frequency spectrum needed. The FCC has mandated that by January 1,
2013, the amount of spectrum being used by each secondary use
licensee must narrow from 25 to 12.5 kHz. In preparation for
this new law, new 25 kHz licenses stopped being granted as of
January 1, 2012.
This new law will dramatically and adversely affect the efficiency
of secondary use spectrum users in the utility market, which
includes all major AMI vendors with the exception of Sensus,
since its 900 MHz primary use system is protected by the FCC.
During transition, interference is expected to increase for users
of the 25 kHz as new, adjacent-channel narrowband systems are
implemented by other licensees. Second, transitioning will require
new equipment purchases. To escape these mandates, some may
choose to operate below 430 MHz. That would, in turn, pres-
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8601 Six Forks Road, Suite 700
Raleigh, NC 27615
1-800-633-3748
Those operating in the secondary use system will soon need to
obtain spectrum for each customer and installation. Obtaining the
spectrum in several areas may prove to be very difficult, if not impossible, because secondary operation may not be as agreeable to
the FCC, since those channels are already taken by primary users.
Conclusion
The essence of the difference between primary and secondary use
licenses can be summed up in a single word: Freedom. Primary
users have the freedom to transmit when they want, and customers can access data when they want. Secondary users are forced to
contend with transmission interference, limited spectrum availability, and the mandate to step aside when primary transmissions
are in play to allow for their unfettered path. Utilities operating
with secondary use licenses are clearly in the back seat - a costly
position from which to operate for its customers.
Utility officials are cautioned to clearly understand how a vendor is
using the word “licensed.” For clarification when evaluating a meter data communications system, learn if the system will operate
with a primary use license that guarantees transmissions, or from
the secondary use spectrum of lower frequency, lower-powered
transmissions.