Federal Communications Commission

Spectrum Policy Task Force

Report of the Spectrum\
Efficiency Working Group

November 15, 2002

**Spectrum Efficiency\
Working Group**

Richard Engelman, International Bureau, Chair

Kwaku Abrokwah, Office of Engineering & Technology

George Dillon, Enforcement Bureau

Gardner Foster, International Bureau

Gordon Godfrey, Media Bureau

Trey Hanbury, International Bureau

Charlene Lagerwerff, International Bureau

Wayne Leighton, Wireless Telecommunications Bureau

Mike Marcus, Office of Engineering & Technology

Roger Noel, Wireless Telecommunications Bureau

Jerilyn Payton, International Bureau

Jennifer Tomchin, Wireless Telecommunications Bureau

John Williams, Office of Plans and Policy

Allen Yang, International Bureau

[Disclaimer]{.underline}

The findings and recommendations contained in this Report are those of
the Spectrum Efficiency Working Group members, and do not necessarily
reflect the views of the Commission, Commission management, or the
Spectrum Policy Task Force.

[Table of Contents]{.underline}

Page

I. Introduction 4

II\. Efficiency Definitions and Measurement 4

# III. Observations on Today's Spectrum Use 9

# IV. Issues and Findings 16

> A. Improving access through power, time, frequency, bandwidth and
> space 17

1.  Fostering technologies for uniform signal strength throughout a
    service area 17

2.  Power limitations 19

3.  Taking advantage of time 20

4.  Taking advantage of space 20

    B.  Permitting other users or uses 21

    C.  Discouraging inefficient use 23

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1.  Receiver performance 24

2.  Defining expectations 25

3.  The noise floor 25

4.  Digital transmissions 26

    B.  Grouping technically-compatible systems 26

    C.  Adjusting regulations as technology develops 27

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V.  Regulatory Models and Incentives for Efficient Use of Spectrum 29

> A. General findings regarding regulatory models 32
>
> 1\. More flexibility 32
>
> 2\. More exclusive use rights 33
>
> 3\. More spectrum commons 33
>
> 4\. Limited application of the command-and-control model 34

VI. Specific recommendations 34

**I. Introduction**

One of the Commission's key spectrum management goals has been to
promote efficient access to and use of the radio spectrum. The
Commission's 1999 *Spectrum Policy Statement* indicated that "\[w\]ith
increased demand for a finite supply of spectrum, the Commission's
spectrum management activities must focus on allowing spectrum markets
to become more efficient and increasing the amount of spectrum available
for use."[^1] Similarly, the Commission's recently released *FY 2003-FY
2008 Strategic Plan* indicates that its general spectrum management goal
is to "\[e\]ncourage the highest and best use of spectrum domestically
and internationally in order to encourage the growth and rapid
deployment of innovative and efficient communications technologies and
services.[^2]

Demand for access to spectrum has been growing dramatically, and is
likely to continue to grow for the foreseeable future. New services,
such as unlicensed wireless internet access and satellite digital audio
broadcasting, are being launched and are quickly reaching hundreds of
thousands of consumers.[^3] Existing services continue to grow at
dramatic rates,[^4] thereby creating demand for access to additional
spectrum. Entrepreneurs are seeking spectrum to offer new services.

At the same time, most "prime" spectrum has been assigned, and it is
becoming increasingly difficult to find spectrum that can be made
available either for new services or to expand existing ones. To ensure
that existing services can continue to grow and evolve to serve
marketplace needs, and that new services have a chance to blossom and
grow, it is important that the Commission continue to promote efficient
access to and use of the radio spectrum.

**II. Efficiency Definitions and Measurement**

In its Public Notice, the Spectrum Policy Task Force (SPTF) asked
whether the Commission should consider ways to quantify or benchmark
efficiency in a way that permits fair and meaningful comparisons of
different radio services.[^5] The SPTF also asked how the Commission
could define and quantify "spectrum efficiency." Based on the responses
to the Public Notice, it is clear that there are many possible
definitions for spectrum efficiency.

The term "efficiency" is commonly used to relate how much output can be
produced based on a certain amount of input. The Random House College
Dictionary, for example, defines efficiency as the "accomplishment of or
ability to accomplish a job with a minimum expenditure of time and
effort," and alternatively as "the ratio of the work done or energy
developed by a machine, engine, etc., to the energy supplied to it,
usually expressed as a percentage."[^6] This can be expressed
generically as:

![](media/image1.wmf){width="1.3819444444444444in"
height="0.46458333333333335in"}

# For spectrum uses, output could be expressed in terms of the amount (or bits) of information transmitted, and input could be expressed in terms of the amount of spectrum (or Hertz) impacted or made unavailable for other use. However, the Working Group recognized that discussions about efficiency also needed to consider other issues, such as the cost of improving efficiency, the number of people being served, and the value of the service that would be provided as a result of the improved efficiency. 

# To assist in the discussions that occurred at the Public Workshops and elsewhere, the Working Group developed three working definitions related to efficiency.

SPECTRUM EFFICIENCY occurs when the maximum amount of information (i.e.,
output) is transmitted within a given amount of spectrum (i.e., input),
or equivalently, when the least amount of spectrum is used to transmit a
given amount of information. This could be expressed as:

![](media/image2.wmf){width="2.8465277777777778in"
height="0.4722222222222222in"}

TECHNICAL EFFICIENCY occurs when all inputs are deployed in a way that
generates the most output for the least overall cost in resources,
including not only the spectrum but also the equipment, other capital,
and labor (i.e., all inputs). This could be expressed as:

![](media/image3.wmf){width="2.7222222222222223in"
height="0.4722222222222222in"}

There is a difference between spectrum efficiency and technical
efficiency. With technical efficiency, the focus is on all inputs,
whereas with spectrum efficiency, the focus is on doing the most with
the spectrum allocated. Just as it would be possible to build a car that
achieves 300 miles per gallon in fuel efficiency, but only by using
advanced lightweight materials that cost a million dollars per car, so
might it be possible to build a radio device that can send and receive
ten times more bits per megahertz, but only by using a lot more of other
resources. In this case, the radio device might have excellent spectrum
efficiency but poor technical efficiency.

ECONOMIC EFFICIENCY occurs when all inputs are deployed in a way that
generates the most value for consumers. With spectrum, the "value"
refers to the value of the information transmitted, whether that is a
"911" emergency call made over a cell phone, a wireless communication
between a manufacturer's plant and its warehouse, a wireless connection
to the Internet for a laptop user, or a radio or television broadcast.
Economic efficiency could be expressed as:

![](media/image4.wmf){width="2.736111111111111in"
height="0.4722222222222222in"}

So, what is the difference between economic, technical, and spectrum
efficiency? While spectrum efficiency creates the most output with the
least amount of spectrum and technical efficiency creates the most
output with the least amount of all inputs, economic efficiency creates
the most value with the least amount of all inputs. One way to think of
the differences is to look at a typical factory production line. A
production line manager is focused on getting the most "widgets"
produced during each job shift (i.e., maximizing the output for a given
input). However, the plant foreman might be looking at getting the most
"widgets" produced at the least cost, varying the number of workers,
utilizing overtime, and buying the cheapest parts to make the widget
(i.e., maximizing the output while minimizing the overall cost). The
company president, on the other hand, might be thinking about whether
the factory line might be better used to make "gizmos" instead of
"widgets" (i.e., maximizing the value of the output while minimizing the
overall cost).

For spectrum, the terms "spectrum efficiency," "technical efficiency,"
and "economic efficiency" allow the various aspects of efficiency to be
considered. One might argue that broadcast television has a higher
spectrum efficiency than mobile telephony service, which in turn has a
higher spectrum efficiency than public safety spectrum use.[^7] These
relationships may also be true for technical efficiency. Yet the value
of a single emergency call placed over a public safety channel in the
course of an hour may exceed that of any of these other uses during the
same hour, and have a higher economic efficiency. Similarly, some
consumers may place more value on a five-minute mobile phone call than
an hour of broadcast television.

It is important to recognize how spectrum and technical efficiency feed
into and become a component of economic efficiency. Business managers
may consider the spectrum and technical efficiency of different services
or technologies, but ultimately they must weigh the cost of each service
against the value created by each. Just because a service or technology
has a high level of spectrum or technical efficiency, it does not follow
that it is the most economically efficient. Such efficiency may cost too
much relative to the value it provides. There may be no market for very
fuel efficient million dollar automobiles. Of course, continued advances
in technology may lower the price of the more spectrally or technically
efficient service, which in turn could change the calculation of that
which is economically efficient.

While the Commission's goal is to promote efficient spectrum access and
use, other considerations also affect Commission policy. Most notably,
various political considerations constrain the policy options available
and thus may constrain the ability to achieve more economic efficiency.
For example, bidding credits for Designated Entities have been used in
some auctions.[^8] While such credits may make it more difficult for the
spectrum resource to move to its highest valued use -- thus constraining
economic efficiency -- they reflect a policy choice made by Congress or
the Commission to weigh efficiency against other worthy goals. Spectrum
and technical efficiency feed into economic efficiency, which can lead
to a policy framework in which other considerations also are weighed.
Some political or other considerations may come at a great cost to
economic, technical, or spectrum efficiency, while other considerations
may impose little or no cost.

# The Commission can promote economic efficiency primarily by providing licensees with a significant amount of flexibility in how they use, and how easily they can transfer, the spectrum. Such "free market" approaches permit licensees to maximize the value of the services they provide within their spectrum. In addition, when warranted, the Commission can promote economic efficiency by making spectrum available for uses that have a high value to the public (such as police and fire communications). 

Occasionally the Commission may find it in the public interest to
constrain the flexibility that licensees have to use or trade their
spectrum. In these circumstances, it may be most important for the
Commission to focus on regulatory policies that can promote spectrum
efficiency (as opposed to technical efficiency -- the Commission cannot
readily assess the cost of all inputs -- or economic efficiency).
However, the Working Group recognizes that in pursuing its goal to
improve the efficient access to and use of spectrum, the Commission must
balance the costs of imposing any improvements in spectrum efficiency
against the costs of achieving that efficiency and the value of the
services that will be provided.

The remainder of this Section focuses primarily on spectrum efficiency,
recognizing that the Commission will rely on free markets to promote
economic efficiency whenever appropriate.

# *Measuring spectrum efficiency.* As mentioned previously, the generic definition of efficiency can be modified for spectrum, where output may be the usable information transmitted (perhaps in bits-per-second) and input is the spectrum resource impacted (in megahertz): 

*Spectrum Efficiency = Information Transmitted (I) / Spectrum Impacted
(U)*

where

*Spectrum Impacted (U) = Bandwidth Impacted (B)\
x Geographic Space Impacted (S) x Time (T) denied to other users*

or simply

*Spectrum Efficiency = I / U = I / (B x S x T)*[^9]

Even this equation is missing some important variables, such as how many
users are being served. It would also be difficult to accurately,
consistently, and fairly pinpoint the amount of information
transmitted.[^10] This equation also doesn't reflect whether any of the
three denominators (bandwidth, space, and time are more valuable than
the others).

# IEEE 802 tries to address one of these concerns by proposing a Wireless Efficiency ("Weff") metric[^11]:

*Weff=(C x Ns )/(B x A) Bit-Users/m^2^*

where:

*Weff* is the efficiency of the wireless system having units of
Bit-Users/meter^2^

> *C* is the capacity of the system in delivery information bits per
> second, after decoding, demodulation, and including the vagaries of
> the network protocol and duty cycle
>
> *Ns* is the number of logical connections or users in the network,
> within the coverage area and utilizing the allocated bandwidth *B*

*B* is the allocated bandwidth to the network in Hertz, and

> *A* is the area covered (in units of square meters) by the wireless
> system over which the bandwidth *B* is uniquely associated.

While this equation doesn't consider the aspect of how much time the
spectrum is being impacted, it could be modified to do so. However, the
difficulty in calculating some of these variables (for example, the
capacity and number of users), and the assumptions behind these
calculations, make measures of spectrum efficiency highly unreliable.

Other parties have suggested ways to measure spectrum efficiency. For
example, ArrayComm suggests that we measure spectrum efficiency using
bits/second/Hertz/cell, bits/second/Hertz/km^2^, or
subscribers/Hertz.[^12] All of the proposed equations involve the
calculation of signal propagation that can vary by frequency, geographic
area, and equipment. Different assumptions about acceptable interference
and desired quality levels would produce different results in terms of
how much bandwidth, space and time would be impacted. And different
parties would likely want to make these calculations using the
assumptions that work most favorably for their situation.

It is also difficult to consider the overall efficiency of a system of
devices, as opposed to a single device. It is generally easiest to
assess spectrum efficiency on a per-device basis, in terms of
bits/second/Hertz. However XtremeSpectrum points out that this value can
be misleading.[^13] Devices with individually low spectrum efficiency
values may nonetheless achieve high efficiencies in combination, where
many such units share the same spectrum over a given area. For example,
radios used for remote reading of utility meters typically transmit only
a few hundred bits per day \-- very low efficiency, by ordinary
standards. But a quarter-million of these devices installed over a few
square miles add up to a combined use of the spectrum that could be
viewed as far more efficient than ordinary radios.

After considering the comments and reviewing the record, the Working
Group concludes that it is not possible, nor appropriate, to select a
single, objective metric that could be used to compare efficiencies
across different radio services. Any metric would provide, inherent in
its assumptions, advantages to certain services and technologies, and
disadvantages to others. The Working Group does conclude, however, that
rough estimates of spectrum efficiency may be useful in certain
situations, as they could allow for some comparisons between
technologies. While not adopting a single metric, the Working Group
still believes it to be possible, and prudent, to promote the efficient
access to and use of spectrum.

# III. Observations on Today's Spectrum Use

There is widespread belief that radio spectrum use in the US is either
crowded or becoming very crowded, and that policy changes are needed to
accommodate growing spectrum demands in both the public sector and the
private sector.[^14] The purpose of this section is to show that there
is some evidence indicating that the shortage of spectrum is often a
*spectrum access problem*. That is, the spectrum resource is available,
but its use is compartmented by traditional policies based on
traditional technologies. New radio technologies may enable new
techniques for access of spectrum and sharing of the spectrum resources
that may create quantum increases in achievable utilization, just like
the major improvement that was made 20-30 years ago with the commercial
introduction of trunking technology and then cellular-based systems.

Neither FCC nor NTIA routinely quantify actual spectrum usage by users
under their jurisdiction. However, during the Summer of 2002 the FCC's
Enforcement Bureau took limited measurements of spectrum use in certain
urban areas which allow a partial view of actual spectrum use. This
effort was limited in duration and only used one site in each city
studied, and hence generally underestimate actual spectrum use to some
degree. However, the Working Group believes that the general
observations made here are likely to have broad applicability and should
be verified in a broader measurement program, possibly in conjunction
with noise measurements

Figure 1 shows the general nature of spectrum occupancy in an
approximately 700 megahertz block of spectrum below 1 GHz in Atlanta,
New Orleans, and San Diego. This data was taken by FCC's Enforcement
Bureau at its offices in each city in June 2002.[^15]

![](media/image5.png){width="6.398611111111111in"
height="5.0055555555555555in"}

In Figure 1 it can be seen that there can be a large variation in
spectrum use intensity within the spectrum below 1 GHz in Atlanta, New
Orleans and San Diego. The lower frequencies in the observed spectrum
tend to have lower utilization than the higher frequencies. Blocks of
frequencies used by television broadcasting and cellular base stations
have continuous occupancy, while other frequencies are more dynamic.

More detail about mobile radio occupancy is shown in Figure 2, which
shows 7.5 MHz of a UHF land mobile band in the same three cities. It can
be seen in this detailed view that land mobile demand is very dynamic,
but there is still a large amount of "white space" in the band that was
monitored.

![](media/image6.png){width="3.6346456692913387in"
height="1.4791338582677165in"}![](media/image7.png){width="3.645669291338583in"
height="1.4653543307086614in"}![](media/image8.png){width="3.601574803149606in"
height="1.4720472440944883in"}![](media/image9.png){width="0.9263779527559055in"
height="1.449212598425197in"}

Single-site monitoring, such as this, tends to underestimate spectrum
use somewhat and a good example is seen here as some bands are heavily
used, while other bands have less use. This behavior may be due to fact
that a given monitoring site is only able to receive signals that are
sufficiently strong at that specific monitoring site. The signals that a
nearby monitoring site is capable of receiving may be quite different.
Furthermore, a given monitoring site is likely to be able to observe
higher-powered broadcast transmitters and land mobile base stations more
easily and at greater distances than lower-power short range mobile
units, particularly hand-held units.

Limited-duration spectrum observations are only useful for estimating
*average* spectrum use. For blocks of spectrum subject to highly peaked
demand, e.g. public safety spectrum, such limited-duration monitoring
may miss the demand peaks altogether. Nevertheless, the existence of
such low average occupancy bands in urbanized areas with increasing
spectrum demand raises interest in the possibility of matching supply
and demand better with alternative technology. Several options for doing
this are discussed elsewhere in this Report.

Up to this point, this Report has focused on the "raw" monitoring data.
However, the data can also be processed to look at the statistics of
spectrum use. For this analysis we looked at a sliding 30-second window
of spectrum observations and computed what fraction of the observed
frequencies were idle during each window.[^16] Figures 3 and 4 show this
type of analysis for two nonadjacent 7 megahertz blocks of spectrum
below 1 GHz. These data again show that while some frequencies are
heavily used, there are other bands that have large parcels of
time-frequency blocks of spectrum available even in high-use urban
areas.

![](media/image10.jpeg){width="6.360416666666667in"
height="2.1777777777777776in"}

**Figure 3: Use of a 7 megahertz band below 1 GHz\
(percentage of a 30-second window by 7 megahertz block that was idle)**

![](media/image11.jpeg){width="6.725in" height="2.25in"}

**Figure 4: Use of a different 7 megahertz band below 1 GHz**

**(percentage of a 30-second window by 7 megahertz block that was
idle)**

This information cannot be used to provide a definitive statement about
present spectrum use, but it can indicate some general characteristics
of spectrum use.[^17] A possible conclusion from these data and their
analyses is that there currently is a large untapped capacity in the
spectrum. If the Commission would develop and implement policies to
permit access to the presently underutilized spectrum use while
preserving the legitimate needs of present users authorized to use the
spectrum, it could meet many of the Nation's growing spectrum needs for
a long time.

In order to verify the above hypotheses more spectrum measurements are
needed in terms of location, time duration, and frequency coverage.
While such measurements usually have been taken only at one location
within an area, there may be benefits of taking measurements
simultaneously at several spots in a grid to minimize the number of
transmissions that are missed and avoid underestimating spectrum
occupancy in the area of interest.

*Public Sector Spectrum Use Characteristics*. In response to the Task
Force's Public Notice seeking comment on spectrum policy questions,
various information were received on the nature of public sector, and in
particular public safety, spectrum use. Public sector use, including
Federal Government civil and military systems[^18], and state and local
public safety systems, constitutes a significant fraction of the VHF/UHF
spectrum that is in greatest demand for mobile systems. This is also a
category of users that has been making increased requests for spectrum
to meet growing high priority requirements. Thus it is appropriate to
make some general observations on the nature of public sector spectrum
use.

While some public sector spectrum use is similar to commercial spectrum
use, the hallmark of much public sector use is the combination of high
peak-to-average traffic ratios and high societal value of the peak
use.[^19] Figures 5 and 6 below illustrate peak and average traffic
statistics that are typical of many types of public sector spectrum use.
These data are from measurements of a single police dispatch channel in
a large city in New York State.[^20]

![](media/image12.png){width="4.836220472440945in"
height="2.872047244094488in"}

**Figure 5:** Traffic on a police dispatch channel measured at different
times

![](media/image13.png){width="3.630708661417323in"
height="2.15748031496063in"}

**Figure 6:** Traffic on a police dispatch channel measured on different
days

The traffic data above is measured in Erlangs, a telephone traffic
term.[^21] The traffic in Erlangs in this case can be interpreted as the
fraction of time that the channel is in use. Thus it can be seen in
Figure 6 that, on a daily basis, channel loading ranges from 0.05 to
0.12 Erlangs, equivalent to occupancy of 5 to 12%. However, during the
same four-week period, occupancy reached a peak during the busiest
15-minute period of approximately 85% on the last day. On most days
during this period, the peak was 50% or less. The hour-to-hour data in
Figure 5 also show 15-minute average usages in the 10% range with
occasional higher peaks. These data are for a dispatch channel that is
probably in more steady use than most law enforcement tactical channels.
Thus it seems likely that other public sector channels probably have
lower average usage but have peaks that are just as high.

While these data imply that peaks are relatively short in duration, the
data in Figure 7 show that peaks might be rather long in extreme
circumstances.

**Figure 7:** Calling data for a New York State county government's
radios\
during January 8, 1998 Northeast ice storm[^22]

While the large surges in public sector communications in conjunction
with the 9/11 tragedy seemed unusual to many, the above data show that
they are not unprecedented. In this case, a large ice storm struck the
Northeast and the county in question had large physical damage,
including large-scale failures in wired communications. It can be seen
from the data that the daily calling levels for the period December 31
to January 4 were in the range of 500-1500 calls/day. Yet on January 8,
the rate was 40,000 calls/day and stayed in the 20,000-40,000 range for
four days. Thus, under exceptional circumstances that occur
infrequently, it is possible for public sector spectrum use to surge to
high peak levels and stay there for multiple days.

The above illustrations indicate that there is significant underutilized
*average* capacity in spectrum resources that are dedicated to public
sector applications. The illustrations also indicate that peak use
demands can fully use, or even exceed, the capabilities of the available
spectrum. Because of the very high value society places on public sector
communications, and in particular public safety communications, the
Commission generally has allocated and assigned public sector spectrum
more closely based on the peak demand rather than the average demand.
This approach raises the possibility that public sector users might be
able to allow other users access to their spectrum during average use
circumstances as long as the spectrum can revert to public sector use
during peak use situations.

Unfortunately, comprehensive data on the peak and average use of public
sector spectrum, and appropriate statistical modeling of such usage, are
not available. The above fragmentary data show that peak-to-average
ratios as high as 80:1 are possible and are associated with very high
public policy priorities. The detailed dynamics of these peaks are also
not well understood. For example, while it is assumed that spectrum use
can surge rapidly, does this correspond to a time constant[^23] of 1
second or a time constant of 10 seconds? The difference between these
two values of time constants could have a large impact on the design of
possible systems to share public sector spectrum subject to the
non-public sector user relinquishing it rapidly in times of peak public
sector demand.

There is also little available information on the frequency of
occurrence of public sector demand peaks and their time distribution.
Knowledge in this area could also be helpful in designing non-public
sector systems that can share public sector spectrum as it would
indicate how frequently the shared spectrum might be preempted by public
sector use.

In summary, better knowledge of the time statistics of public sector use
could contribute to both improving communications for public sector
users as well as providing preemptable access to such spectrum to other
users who in turn could compensate public sectors users for such
spectrum access.

# IV. Issues and Findings

# As mentioned previously, the Working Group has concluded that a single objective metric that could be used to compare efficiencies across different radio services is neither possible nor appropriate. This Report therefore does not attempt to identify specific services that are more efficient, or less efficient, than others. Such assessments clearly would be debatable, and would depend on assumptions that may not be comprehensive. Instead, the Working Group believes the Commission should take a number of specific steps to encourage the efficient access to and use of the spectrum.

There are two basic situations that impact how spectrum efficiency can
be improved:\
(1) situations in which all spectrum in an area is already assigned but
not fully used; and (2) situations in which all spectrum is fully used.
In the first situation, which can be referred to as "access limited,"
spectrum efficiency can be improved by increasing the access that other
users have to the spectrum. In the second situation, which can be
referred to as "throughput limited," efficiency can really only be
improved by taking steps that permit existing users to provide greater
information transfer rates. One could view the first situation as
increasing capacity by putting in more pipes, and the second situation
as increasing capacity within the existing pipes.

This section identifies several steps that can be taken to improve the
efficient access to and use of spectrum. Options include: (1) improving
access through power, time, frequency, bandwidth, and space; (2)
permitting other users or uses; (3) discouraging inefficient spectrum
use (or encouraging efficient spectrum use); (4) grouping
technically-compatible systems; and (5) adjusting regulations as
technology develops. Figure 11 shows the relationship of each of these
options to access-limited or throughput-limited situations. The
observations on current spectrum use indicate that in many locations, on
many frequencies, and at many times, the spectrum is not being fully
used. The Working Group believes, therefore, that both access-limited
and throughput-limited options may be suitable for improving efficiency
in many situations. As access to spectrum is expanded, however, the
Commission may be left only with solutions that address
throughput-limited situations.

Figure 11 -- Steps that can be taken to improve spectrum efficiency

> **A. Improving access through power, time, frequency, bandwidth, and
> space**

The examination of current spectrum use indicates that often, even
though the spectrum in a general area may be licensed, the spectrum is
not being fully utilized. Additional capacity, and therefore expanded
spectrum efficiency, could be created by permitting access to the
spectrum by other users on a time, frequency, bandwidth, or space basis.
For example, new operations could be permitted at times when the current
licensee isn't using the spectrum (but shutting down when the licensee
does operate). Operations that aren't frequency sensitive could be moved
to less crowded spectrum bands. Existing operations could operate with
less bandwidth. And additional licenses could be issued for geographic
areas that aren't congested already (for example, rural areas). Other
technical changes, such as changing the power of transmissions, could
also be implemented to improve technology.

1.  **Fostering technologies for uniform signal strength throughout a
    service area**

Radio transmission facilities are usually designed to provide a
specified "acceptable" signal level over a desired service range.
Because the level of the transmitted signal decreases as one moves away
from the transmission antenna, this design usually results in
unnecessarily high (and therefore inefficient) signal levels near the
transmission antenna. If these signals are strong enough, they can cause
interference to users on other frequencies, either because the
transmitting facility is radiating spurious signals on other frequencies
at a high enough level to cause interference, or because the receiving
facility on the other frequency cannot easily cope with the high level
of the transmitted signal ("receiver overload").

![](media/image14.wmf){width="5.995833333333334in"
height="2.964583333333333in"}

Figure 12 - Impact of Frequency and Antenna Height on Spectrum Use

While it may not be possible to completely overcome the physics of radio
wave propagation, which makes signals decrease as distance is increased,
it is possible to implement technologies, such as "cosecant-squared"
antennas and low-power transmission networks, that restrict the
radiation towards the ground near to the transmitting antennas, and
increase the signals at distances. These technologies would increase
efficiency by permitting operators to reduce transmitter power levels to
maintain the same coverage (or provide increased coverage with the same
power). They could also protect adjacent channel operations from being
impacted by near-by transmissions.

Often the Commission's rules already permit the use of such
technologies. But in some services (for example, broadcasting), the
Commission's rules prohibit the deployment of low-power transmission
networks. The Commission should consider changing its rules in this
regard. It also may be appropriate to consider incentives that could
promote the use of such technology. This Report discusses elsewhere the
possibility of setting interference temperature thresholds that would
establish the level of interference protection of which an incumbent
operator could be assured, while potentially permitting operations by
other users in the band as long as they do not cause the interference
temperature threshold to be exceeded. One possible incentive that could
be offered to users of uniform signal generation technology is to
establish a reduced interference temperature threshold (or a more
protective interference environment), as shown in Figure 13. This
reduced interference temperature threshold would likely yield increased
capacity, and potentially improved efficiency, to the licensee.[^24]

# ![](media/image15.wmf){width="5.9847222222222225in" height="2.84375in"}

**Figure 13 - Impact of Maximum Power Flux Density on\
Proposed Interference Temperature**

2.  **Power limitations**

There is a tension between having enough power to ensure coverage over a
desired service area and not having so much power that it puts strong
cost burdens on adjacent channel operations (in order to prevent
receiver overload or to filter spurious emissions). High-power
transmitters generally reduce the capacity (and therefore potential
efficiency) for adjacent-channel users. This is a particular problem in
urban areas, where the spectrum is likely to be more crowded, but is
much less of a problem in rural areas, where spectrum use may be sparse.

To address this situation, it would generally be desirable for the
maximum transmitted power levels to be lowered in urban environments and
increased in rural environments. Power can be reduced through the
deployment of low-power transmission networks, such as those currently
used in cities by cellular and PCS service providers. By having more
transmitters, the capacity for transmitting information can be increased
(since each transmitter can only serve a limited number of users in a
typical two-way environment). Power in rural areas can be increased by
permitting even higher power levels. This could enable service to be
provided in areas that can't be economically justified now.

> **3. Taking advantage of time**

Industry has developed several different technologies that can be used
to exploit the gaps in time in which a particular frequency is being
used. Early mobile radio systems were developed so that a group of users
would share a specific, fixed radio frequency. The transmitters and
receivers for each group of users were designed to operate on a fixed
frequency. However, over time it became clear that there were great
differences in the amount of usage, or congestion, on different
frequencies. Trunked radio systems were developed to address these
concerns. In a trunked system, all of the users can use any of the
channels. Channels that are not currently being used are identified and
an unused channel is made available to each user. Trunking in the early
mobile radio systems was implemented manually. The user could select an
available channel manually by switching from one channel to another and
listening for an unused channel.

In the mid 1960's a form of automatic trunking was implemented using a
technique called "marked-idle," where a tone was placed on one of the
available channels. A mobile radio could then automatically select the
open frequency channel by finding this tone. The advantage of a trunked
system is that many more users can be supported in the same amount of
spectrum with the same grade of service.

Another idea to take advantage of time is to allow a secondary party to
access the spectrum when the licensee is not using it. This could
involve interruptible use of the spectrum. Secondary parties (parties
that could operate but had to protect the primary licensee) could use
technology that would automatically monitor the channel before
transmitting to ensure that it is really vacant. Also, a time limit or
similar regulatory requirement could be placed on the secondary
operation to ensure the licensee could access it when needed.

**4. Taking advantage of space**

Spectrum capacity, and hence potential spectrum efficiency, can also be
improved by taking advantage of the geographic distances between radio
transmitters. Existing licensees often install only enough radio
transmitters to provide service in areas that they believe offer the
best business potential. This can result in a lack of service (or
spectrum use) in some geographic areas away from the transmitters. These
holes in service, called "white areas," can be made available to other
licensees that want to provide service in that area.

The Commission already permits some geographic-area licensees to
partition (or divide) their service areas and trade off the transmission
rights.[^25] However, this freedom is not available in all services. In
cases involving site-specific licensees, the Commission can authorize
new licenses that can provide service in unserved white areas.

> **B. Permitting other users and uses**

Commenters have made clear in written comments and during our workshops
that spectrum lies fallow in certain areas, at certain times, and on
certain frequencies.[^26] For example, a licensee may have exclusive use
of spectrum in a particular geographic area, but choose not to make use
of the spectrum over the entire area. Likewise, the licensee may use the
spectrum heavily during the daytime, but have light or no usage during
nighttime hours. Finally, a licensee may fully utilize spectrum during
times of peak usage, but utilize only half of its spectrum during
off-peak hours. The commenters observe that spectrum efficiency can be
maximized by improving access to spectrum in such instances. This
comports with our observations about current spectrum use.

While licensees may be aware that such efficiencies can be gained, there
are at least two reasons why a significant number of licensees aren't
fully taking advantage of this opportunity. First, a licensee may wish
to more fully utilize its spectrum, but is prevented from doing so by
the technical or operational regulatory constraints imposed on the radio
service by our rules. Such regulatory constraints may constitute a
"catch-22" in many cases where development of advanced radio technology
is hindered by the current rules, preventing such operation and thereby
inhibiting the full utilization of the spectrum. Second, a licensee may
wish to permit others to utilize its spectrum on a short- or long-term
basis in certain areas, at certain times of day, or on a shared basis,
but is effectively prevented from doing so because of regulatory
prohibitions or high transaction costs. In this vein, third parties may
wish to use the licensee's spectrum on a secondary, non-interference
basis, but are often prevented from doing so by regulatory constraints.

One of the keys to improving spectrum efficiency is through improving
access to spectrum. Therefore, the Working Group recommends that the
Commission take steps to promote: (1) flexible use of spectrum; (2)
development and deployment of advanced technologies; and, (3) secondary
markets for spectrum. First, promoting flexible use of spectrum may be
in the form of relaxed regulatory requirements for existing licensees or
increased access (on a secondary, non-interference basis) to spectrum by
third parties. For example, licensees may be in a position to more fully
utilize their spectrum if they are permitted to provide a full range of
mobile, fixed, broadcast, or hybrid services.[^27] Likewise, third
parties may well be in a position to utilize the spectrum on a
secondary, non-interference basis by, for example, transmitting at low
power, spreading the signal over a large bandwidth, or maintaining some
other means of time or space diversity. There may be instances where,
based on the specific circumstances of the bands or users in question,
increased flexibility and access by third parties may not be desirable
or result in a net gain in efficiency. The Commission will need to fully
consider the potential impact to licensed users, consumers, and others
in deciding whether to implement this type of policy in a particular
spectrum band.[^28]

Second, access to spectrum may be increased via the development and
deployment of advanced technologies. As the commenters and workshop
participants point out, advanced radio technologies have been developed,
and are being developed, to increase the amount of information in a
radio channel, while at the same time increasing the number of
independent users in a particular geographic area.[^29] Many of the
commenters voice support for "smart" radio and infrastructure
technologies that to some extent embed spectrum management decisions
into the radio system. Such technologies are capable, for example, of
real-time monitoring of a radio channel or spectrum band and limiting
transmissions in terms of frequency, power, or timing in order to avoid
harmful interference to other spectrum users. We recommend that the
Commission provide for the development and deployment of such
technologies. One way to promote development of these technologies is to
provide regulatory certainty in the testing and allocation of spectrum
for such devices, thereby enabling entrepreneurs and businesses to
obtain financial backing for such ventures.

Third, we recommend that the Commission take steps to promote a
secondary market for radio spectrum. In a *Notice of Proposed Rule
Making* released November 27, 2000, the Commission initiated a
proceeding to examine removing unnecessary regulatory barriers to the
development of more robust secondary markets in radio spectrum usage
rights.[^30] At that time the Commission stated that it believed
enabling the development of more robust secondary markets would help
promote spectrum efficiency and full utilization of Commission-licensed
spectrum, thereby increasing access to spectrum for those that desire
it. The commenters and workshop participants generally agree with this
position and recommend that the Commission move swiftly to enable such
secondary markets, thereby improving access by lowering transaction
costs for licensees.[^31] Removing these regulatory barriers will go a
long way toward encouraging more spectrally efficient technologies, full
utilization of spectrum in all areas, and increased access to spectrum
for those that wish to implement innovative, spectrally efficient
technologies.

Finally, it is clear that, because of the highly variable rate of
transmissions, public safety stations have a lot of additional capacity
in non-peak times. This spectrum could be exploited by permitting the
existing public safety licensee to authorize others to use its spectrum.
Under this scenario, the public safety licensee itself would have to
ensure that it gets adequate access to the spectrum when it need
spectrum (but other users could operate during non-transmission time
periods).

> **C. Discouraging inefficient use**

One of the core principles of effective spectrum management is to
maximize the efficient use of the radio spectrum. The FCC shares
spectrum management responsibilities and functions with the National
Telecommunications and Information Administration (NTIA). While the FCC
has authority over commercial spectrum usage as well as that of local
and state governments, NTIA manages the federal government's use of
spectrum for defense and other federal purposes.[^32]

The Working Group recognizes that in some services there currently is no
stimulus for efficient spectrum use. Generally, licensees that have paid
to acquire their spectrum have a marketplace incentive to use their
spectrum efficiently. Potential inefficiency, therefore, is more likely
to occur in narrow-use services, where spectrum can't be easily brought
to the marketplace, and among licensees who have not been forced to
incur the opportunity cost of acquiring spectrum.[^33]

One way to encourage operators to employ a more efficient system is to
establish a fee structure that encourages efficient use of the
spectrum.[^34] Another way is to mandate improvements such as transition
to digital service or narrower bandwidths.[^35] Some commenters propose
that Congress provide some incentives because rural communities may not
have the tax base, or the resources, to make these changes.[^36]
Stricter unwanted emissions limits would also increase efficient
spectrum use.[^37]

Some participants of the Public Workshop on Spectrum Efficiency
suggested a shift to hybridizations, with wireline delivery whenever
possible.[^38] Deploying a system that uses fiber, cable, and wireline
in concert with wireless applications could reduce spectrum congestion.
This would save valuable spectrum for those services that require
mobility.[^39]

Another participant speculated that it is not going to be a mandate that
invokes the change to efficiency, but the universal driver of
profitability of special offerings. The public will choose spectrally
efficient devices and services that they can use. TV viewers will choose
DTV because it will have more content and more services.[^40]

**1. Receiver performance**

In the past, the FCC has shied away from imposing standards on receivers
and has not protected their reception from new services. However,
reports of adjacent channel interference to receivers, especially in
older, more established services, have led many commenters to believe
there is a need to adopt receiver "standards," or performance
requirements.[^41] Under the current FCC approach, many new service
providers must allow for a guard band or lower power to protect the more
established operation of other users, especially if they are public
safety entities. This poses a cost on the new operator and is viewed by
some commenters as spectrally inefficient. CTIA proposes that the FCC
ensure that Public Safety first responders deploy upgraded receiver and
networking equipment designed to improve intermodulation rejection
characteristics.[^42] In addition, unlicensed band use may lead to
devices that are inexpensive but vulnerable to interference or that
cause interference.[^43]

The real problem with setting receiver performance requirements is how
to approach each service. Those who design commercial mobile receivers
generally have to provide a large front end to account for Doppler
shift.[^44] Adding out-of-band rejection capability and more strict
selectivity may make the receivers cost too much and compromise the
quality of the service (because as the bandwidth narrows, so does the
voice quality). Coding methods and band-limiting filtering is more
efficient, however.[^45] In an urban environment, selectivity is more
important, so that the receiver could pick out an individual channel
without interference. In a rural area, sensitivity is more important so
the receiver can employ signal processing techniques and improve the
quality of the signal. System design has an impact on the receiver's
ability to perform as well. Public safety designs usually feature a
single repeater that is intended to be used by all. This makes their
operation vulnerable to interference from local cellular-type systems,
especially if the public safety receivers are designed for sensitivity
and not selectivity.

Some commenters would like to fully use the spectrum assigned for
broadcasting service but because of the sensitivity of the receivers
sold, they must overcompensate for theoretical interference. These
"taboos" in the UHF band allow 1 out of 6 channels to be used in a
market[^46]. If TV receivers were made with more selectivity, more TV
channels would be able to be used in a market thus leading to greater
efficiency and diversity.

**2. Defining expectations**

This Report contains a number of recommendations that the Commission
take steps to better explain the interference protection requirements
that licensees are expected to tolerate. There must be a balance between
providing consistent and reasonable protection of licensee operations
and enabling new use of the spectrum by systems that will not reasonably
cause interference. This Report discusses the "interference temperature"
concept, which would set a threshold of protection for licensees and
allow other operations in the same frequency band and geographic area as
long at the interference temperature threshold is not exceeded. This
concept makes sense from a spectrum efficiency standpoint. Existing
licensees often have to design their systems to be tolerant of "worst
case" interference levels that they cannot easily project. This can
result in the use of guard bands or costly filters that protect against
the worst case. In can also result in demands that new entrants operate
at lower power or with fewer transmitters, based on claims from the
existing licensees that they are entitled to protection.

The Commission generally establishes protection requirements each time
it authorizes a radio service. This can be a time-consuming and
acrimonious process and can often result in different protection levels
for difference services. This ad hoc approach, where protection
requirements are set individually for each specific service, slows down
the deployment of new services. The interference temperature approach
would add certainty for existing licensees, permitting them to design
their interference protection mechanisms in an economically efficient
manner.

**3. The noise floor**

A wide variety of radio emissions create the "noise floor," the
cumulative level of radio emissions on a particular frequency at a
particular location. Radio emissions that make up the noise floor
include: communications signals from licensees that are transmitted
within their frequency band; out-of-band or spurious emissions from
licensees on other frequencies; signals transmitted on a
"non-interference basis" from low power communications devices, such as
cordless telephones and other intentional radiations regulated under
Part 15 of the Commission's Rules; emissions from Part 15 unintentional
radiators, such as computer systems; and radiations that generated
within the natural environment. These signals add together, creating a
dynamically variable noise floor that can affect the performance of
radio systems.[^47] The noise floor, which can be measured and
monitored, has been likened to pollution and it may be difficult or
impossible to track each and every contributor to the noise floor in
each and every environment.

The interference temperature concept takes advantage of having a
real-time knowledge of the noise floor at a specific location and point
in time, potentially permitting the noise floor to be increased when it
won't cause harmful interference and decreased when a harmful
interference threshold is exceeded. To establish, and maintain,
interference temperature thresholds, it will be important that the
Commission, or other parties, extensively monitor the noise floor,
identifying potential problem areas and opportunities for new entry.

**4. Digital transmissions**

Most transmissions use analog technology. However, there are real
advantages in many situations for licensees to convert to digital
technology. For example, digital television signals are able to provide
comparable service levels with far lower transmitted power. In addition,
digital transmissions can avoid certain "taboos" that create inefficient
use of the spectrum. Finally, it is easier to predict the interference
consequences from digital transmissions.[^48]

The Working Group finds that an expansion in the use of digital
technologies would lead to increases in spectrum efficiency. Therefore,
the Working Group believes that the transition to digital transmission
techniques should be promoted and hastened by policy, and if necessary,
by rules. However, this promotion should only be done when the benefits
of the use of digital technologies exceed the cost of deploying them.

**D. Grouping technically-compatible systems**

The Commission has generally tried to group technically-compatible
transmissions together as it established its frequency allocations over
the years. However, the Commission has been faced occasionally with
addressing interference concerns that result from having high-powered
radio transmissions located near in frequency to services that require
highly-sensitive receivers. Such situations often result in one service
having to constrain the power or locations that can be used, or another
service having to use expensive filters or guardbands to protect against
the effect of the transmissions of other services. As mentioned
previously, such filters and guardbands reduce spectrum, and economic,
efficiency.

# The Commission has been transitioning towards allocating spectrum for broad, flexible uses. This can result, however, in a higher level of unpredictability about the potential radio interference environment (e.g., How much power will one use require? What level of protection will another use require?). It can also force the Commission to get involved in disputes between licensees.

It would be desirable, over time, that the Commission continue it
efforts to group allocations together in frequency based on
mutually-compatible technical characteristics (power and sensitivity to
interference). The Commission should also work to improve the
out-of-band interference performance of transmitters and receivers over
time so as to reduce the need for this kind of grouping.

**E. Adjusting regulations as technology develops**

While technology advances continue to promote the efficient use of
spectrum, regulatory approaches to spectrum management must adapt as
well. These adaptations to the Commission's spectrum management approach
could lead to changes in rules, policies, and incentives placed on
license holders. The Commission periodically should evaluate its
allocation parameters as technology evolves. In addition, as discussed
in Section V, the Commission should adopt regulatory models and
incentives that promote efficient spectrum allocation and remove rules
that create barriers to putting spectrum to its highest valued use.

Many commenters agree with this approach. One commenter asserts that
rules limiting flexible use of frequencies should be removed and laws
and procedures blocking access to unused or under-utilized bands by new
entrants should be eliminated.[^49] Furthermore, by prohibiting only
additional spectrum uses that cause "harmful interference," and by
permitting all other uses of the spectrum, the Commission can both
protect current spectrum uses and allow new technologies to develop and
flourish.[^50] More specifically, one commenter argues that the
Commission should adopt a policy whereby parties that request new
spectrum should be required to submit a "Spectrum Impact Study" that
shows a demonstration of non-interference, the obstacles to efficient
sharing, the cost of integration and reallocation for both new users and
incumbents, and a proposed transition scheme.[^51]

Commenters argue that the determination of whether to reallocate
spectrum should be guided by the market, but when market failures can be
reliably predicted, it may be appropriate to modify the standard
allocation and assignment process in order to achieve other goals.[^52]
However, they argue that the Commission should not adopt different
spectrum allocation and assignment policies for different portions of
the spectrum or different geographic regions. Commenters further assert
that the U.S. government should use a rolling spectrum planning process
that would include both long-term goals for spectrum use, as well as
short-term plans to achieve the goals through specific allocation
decisions.[^53] They also argue that spectrum planning must
comprehensively address all spectrum, and such planning will require a
more effective coordination process between NTIA and the
Commission.[^54] Another Commenter agrees but argues that the Commission
should proactively address the Commission's current allocation policies
as they are in need of major reform and should intensify its search for
spectrum being inefficiently used that should be candidates for
reallocation.[^55]

Some commenters raise concerns about changes in Commission policy as
they believe that current Commission rules optimize the efficient use of
scarce resources and that the deployment of advanced technologies will
continue to move forward as markets increasingly provide returns to more
efficient systems.[^56] Furthermore, some commenter suggest that, with
the Commission's established flexible mechanism for coordinating within
the general interference standards, there is no need for the FCC to
expend any of its resources to update its rules, unless the rules are
based on technologies or assumptions that are no longer valid.[^57] They
argue that the Commission should not have to concern itself with
spectrum efficiency in applications for which the licensee has obtained
spectrum rights at auction or has the opportunity to resell or subdivide
spectrum rights.[^58]

The Working Group agrees that the Commission should review and adjust
its regulations over time as technology develops. Specific
recommendations for changes include[^59]:

> a\) adjusting interference temperature threshold requirements downward
> over time, which would permit increased throughput and capacity within
> existing spectrum assignments;
>
> b\) adjusting transmitted powers downward in response to reductions in
> interference temperature thresholds, which would also permit increased
> throughput; and
>
> c\) adjusting limits on out-of-band emissions downward over time,
> which would reduce the noise floor and provide other users with the
> ability to increase throughput.

***Advisory groups.*** The Commission often has relied on outside
advisory groups to help address spectrum issues, most recently relying
on the Technical Advisory Council ("TAC"). The TAC is a Federal Advisory
Committee Act committee comprised of a broad array of well-known
technologists. It was formed in 1998 to provide the Commission with
technical insights concerning innovations in communications and related
industries and to make recommendations on issues presented to it by the
Commission. An ongoing effort of the TAC is the Spectrum Working Group.
This Group has been tasked by the Commission to assess and report to the
TAC the current state of advanced wireless technologies and suggest ways
that the availability of such technologies might affect the FCC's
traditional approaches to spectrum management.

The Commission has also recently participated in other Working Groups
that address spectrum policy issues such as the Public Safety National
Coordination Committee ("NCC") and the Network Reliability and
Interoperability Council ("NRIC"). Both the NCC and the NRIC's charter
require that their membership should be solicited from a broad range of
representation including the manufacturing, technology, public policy,
network reliability, design and service provider communities as well as
local, state, and federal agencies.

Industry participation in spectrum policy discussions will continue to
translate into more informed policy decisions and the establishments of
formal spectrum policy working groups could facilitate these
discussions. Among the commenters encouraging a more comprehensive
participatory approach to spectrum policy, the Information Technology
Industry Council ("ITI"), in particular, asserts that greater
cooperation between government and non-government entities will not only
provide the government with important engineering and business
expertise, but also promote understanding among competing
interests.[^60]

The Commission should call on the Technical Advisory Council's Spectrum
Working Group, or other suitable advisory group, to further evaluate and
collect information on the issues raised by this Report and subsequent
Commission policy-making activities. The Commission should also
periodically coordinate and report on recommendations of the spectrum
policy working groups in which the Commission participates. These
reports should focus especially on recommendations that could lead to
changes in rules, policies and incentives.

# V. Regulatory Models and Incentives for Efficient Use of Spectrum

The Working Group examined the Commission's spectrum policies and rules
defining spectrum usage rights in relation to three general models. The
advantages and disadvantages of each model, along with the factors that
favor the application of one model over the others, are mentioned here
and examined in greater detail in the Report of the Spectrum Rights and
Responsibilities Working Group.

-   ["Command-and-control" model.]{.underline} The traditional process
    of spectrum management in the United States, currently used for most
    spectrum within the Commission's jurisdiction, allocates and assigns
    frequencies to limited categories of spectrum users for specific
    government-defined uses. Service rules for the band specify
    eligibility and service restrictions, power limits, build-out
    requirements, and other rules.

-   ["Exclusive use" model.]{.underline} A licensing model in which a
    licensee has exclusive and transferable rights to the use of
    specified spectrum within a defined geographic area, with flexible
    use rights that are governed primarily by technical rules to protect
    spectrum users against interference. Under this model, exclusive
    rights resemble property rights in spectrum, but this model does not
    imply or require creation of "full" private property rights in
    spectrum.

-   ["Commons" or "open access" model.]{.underline} Allows unlimited
    numbers of unlicensed users to share frequencies, with usage rights
    that are governed by technical standards or etiquettes but with no
    right to protection from interference. Spectrum is available to all
    users that comply with established technical "etiquettes" or
    standards that set power limits and other criteria for operation of
    unlicensed devices to mitigate potential interference.

Each of these models represents an ideal. In general, each has some
characteristics that can promote efficient use of the spectrum, though
the ability of each model to promote efficiency varies depending on
market conditions. In addition, there is some overlap among these models
as well as variations that combine elements of each. For example,
spectrum users that are regulated on a command-and-control basis may
have some of the same rights as spectrum users that are subject to the
exclusive use model (*e.g.,* exclusive and transferable rights,
interference protection). Moreover, spectrum that is subject to the
exclusive use or commons model may also be subject to some degree of
command-and-control restriction (*e.g.,* limiting usage based on
international allocation restrictions). Nonetheless, the key distinction
between the command-and-control approach and the other two models is
that it typically imposes much greater usage restrictions on spectrum
(and sometimes on the eligibility of spectrum users).

Commenters and participants in the workshops generally criticized the
costs and inefficiencies imposed on spectrum users and the public by
command-and-control regulation, and argued that these costs could be
substantially reduced by moving to more flexible, market-oriented
approaches, whether under an exclusive use model, a commons model, or a
combination of the two.[^61] Some commenters, however, argued in favor
of retaining a command-and-control approach for certain services
(*e.g.,* public safety) on the grounds that exclusive reliance on
market-based spectrum usage models would undervalue or thwart the
provision of such services.[^62] Moreover, while most commenters and
workshop participants favored expanded application of flexible,
market-oriented spectrum policies, there was a significant split among
those who favored an exclusive use approach and those who favored a
commons approach.

Commenters who favored the exclusive use model noted that it is built on
the assumption that there is scarcity in the spectrum, at least at some
times and in some places.[^63] They asserted that this scarcity may be
the result of limited access, or an excess of spectrum use relative to
capacity. They explained that the exclusive use model promotes economic
efficiency because its key characteristics -- clearly defined rights,
exclusivity, flexibility, and transferability -- are necessary for
efficiently allocating any scarce resource among competing uses. They
also argued that without exclusive rights and interference protection,
spectrum users would face uncertainty and would lack the incentive to
invest in new technologies or services. These parties also tended to
express skepticism regarding the commons approach, contending that a
spectrum commons would result in overuse, interference, and
underinvestment.

Supporters of the commons model argued that it leads to greater
technological innovation and spectral efficiency than an exclusive use
approach.[^64] These parties maintained that, because no spectrum is
exclusively held, spectrum commons users have the incentive to create
spectrally efficient frequency-hopping technologies, whereas licensed
spectrum typically sits idle when the license-holder is not
transmitting. Furthermore, proponents of an open, commons approach
argued that spectrum scarcity might actually be reduced under such a
regime because of the efficiency-enhancing possibilities and
fundamentally different spectrum demands of new system architectures
such as mesh networks. Commenters also contended that even in spectrum
that was otherwise subject to an exclusive use approach, a commons
approach should be used to create "underlay" rights for low-power,
non-interfering devices.

Despite this split, most commenters and workshop participants supported
the proposition that in spectrum policy, "one size does not fit all,"
and that the Commission spectrum policy should therefore strike a
balance between the exclusive rights and the commons models.[^65] For
example, many commenters suggested that granting flexible exclusive use
rights to spectrum users did not preclude the Commission from imposing
some regulatory limitations on use, analogous to zoning restrictions
that are placed on property owners by local governments. Other
commenters argued that unlicensed spectrum should not be seen as a
replacement for licensed spectrum, but that some spectrum should be set
aside for unlicensed use in the same manner that some land is set aside
for public parks.[^66]

The Spectrum Efficiency Working Group agrees with the consensus view
expressed by many participants in this process that "one size does not
fit all" in spectrum policy. We therefore recommend that the Commission
advance efficiency by basing its policy on a balance of the three
spectrum rights models: an exclusive use approach, a commons approach,
and (to a more limited degree) a command-and-control approach. We
further recommend that the Commission fundamentally alter the existing
balance among these models -- which is dominated by legacy
command-and-control regulation -- by expanding the use of both the
exclusive use and commons models throughout the spectrum, and limiting
the use of the command-and-control model to those instances where there
are compelling public policy reasons.

The recommendation to move towards greater reliance on the exclusive use
and commons models requires that the Commission also determine the
appropriate balance between these two models. There are a number of
variables that may be relevant to this determination with respect to any
particular band, but two of the key factors to be considered are (1)
spectrum scarcity, and (2) the transaction costs associated with moving
spectrum to more efficient use. By "spectrum scarcity," we mean the
degree to which demand exceeds the current supply for that particular
spectrum. By "transaction costs," we mean the expenditure of time and
resources required for a potential spectrum user to obtain the spectrum
access rights from one or many parties necessary to its proposed
spectrum use.

The exclusive use model should be applied to significant parts of the
spectrum, particularly in bands where scarcity is relatively high and
the transaction costs associated with market-based negotiation of access
rights are relatively low. Where spectrum is scarce but transaction
costs are high, the exclusive use model still may be most appropriate,
since wherever scarcity exists, there will be competing claims to this
resource, and the exclusive use model is most effective at balancing
these claims.

The commons model also should be applied to significant portions of the
spectrum, particularly in bands where scarcity is low and the
transaction costs associated with market mechanisms are high. Where
spectrum scarcity and transaction costs are both low, the commons model
may be the most appropriate, though it also is possible that the
exclusive use model would provide comparable benefits, as the lack of
spectrum scarcity means that its price will be close to zero.

Finally, the command-and-control model should be applied only in
situations where prescribing spectrum use by regulation is necessary to
accomplish important public interest objectives or to conform to treaty
obligations. Service regulated in this manner should have to clear a
high bar so as to separate public interest objectives from special
interest requests for particular types of regulation.

> **A. General findings regarding regulatory models**

**1. More Flexibility**

One solution to the inefficiencies associated with command-and-control
regulation is to grant licensees greater authority to determine the
highest valued use of their spectrum.[^67] In its *Spectrum Policy
Statement*, issued in 1999, the Commission observed that, "(i)n the
majority of cases, efficient spectrum markets will lead to use of
spectrum for the highest value end use," [^68] and "\[f\]lexible
allocations may result in more efficient spectrum markets."[^69] Rather
than make judgments about spectrum use that are more regulatory than
that required by the public interest and the international coordination
process, the Commission has held that authorizing more flexible spectrum
uses promises both immediate and future innovations without consuming
additional spectrum resources.[^70]

We agree that authorizing more flexible uses may increase the supply of
new innovations and services. Furthermore, we find that increased
flexibility will be a key component of any policy that successfully
promotes the efficient use of spectrum. Accordingly, we recommend that
the Commission grant spectrum users the maximum possible autonomy to
determine the highest valued use of their spectrum, subject only to
those rules that are necessary to afford reasonable opportunities for
access for other spectrum users and to prevent or limit interference
among multiple spectrum uses. We find that a significantly expanded
application of both the exclusive use and commons models, along with
application of the command-and-control model that is limited to specific
exceptions, is the most effective way to promote this flexibility.

**2. More Exclusive Use Rights**

Granting -- to the greatest degree possible and consistent with other
policy goals -- rights to exclusivity, flexibility and transferability
may create significant incentives for efficient spectrum use. We
recognize that these are the key components of the exclusive use model
and thus believe this model may be particularly effective at creating
these incentives for efficient use. At the same time, we note that the
spectrum commons or command-and-control model may incorporate some of
these rights as well. For example, additional flexibility or
transferability could be pursued to a limited extent under the
command-and-control model. In addition, granting additional flexibility
in spectrum use is consistent with the spectrum commons model (although,
clearly, exclusivity is not).

In short, the Commission should look to strengthen the incentives for
efficient use of spectrum across the board, a policy that often will be
best promoted through strengthening the rights of licensees.
Specifically, the Working Group recommends that the Commission apply the
exclusive use model to much of the spectrum, particularly in bands where
scarcity is high and transaction costs are low. These conditions
primarily exist below 5 GHz, but may also occur in some higher frequency
bands.

Ultimately, wherever spectrum scarcity exists, there will be competing
claims to the resource, and the exclusive use model is most effective at
balancing these claims. However, this observation does not preclude the
introduction of unlicensed "underlays" in exclusive use bands, which may
provide additional efficiency benefits.

**3. More Spectrum Commons**

The Working Group recommends that the Commission set aside additional
spectrum for spectrum commons. Such spectrum is particularly conducive
to certain types of innovation and the creation of new technologies and
services. Like a national park, a spectrum commons would be open to all
parties that abide by certain rules and/or etiquettes that are necessary
in order to ensure efficient use of the spectrum and minimize
interference. The Working Group also recommends that, in addition to
allocating more unlicensed spectrum, the Commission permit unlicensed
devices that can operate within licensed bands without interfering with
licensees (*e.g.*, UWB) to do so, with certain conditions (*e.g.*,
limited to particular bands).

Specifically, the Working Group recommends that the Commission apply the
commons model to significant portions of the spectrum, particularly in
bands where scarcity is low and transaction costs are high. These
conditions primarily exist in the higher microwave bands, especially
those above 50 GHz, based on their limited propagation characteristics.
Continuing and expanding the use of the commons model in some lower
bands also is important to encourage the development of low-power,
short-distance communications and emerging technologies. Finally, the
commons model also is appropriate for defining underlay rights.

**4. Limited Application of the Command-and-Control Model**

While most spectrum allocations may no longer be appropriate for the
traditional model of command regulation, there may be good reasons for
the Commission to retain this approach for certain services. For
example, radioastronomy may need to have dedicated, protected spectrum
bands for the foreseeable future, due to its highly sensitive
applications and the fact that its benefits accrue to society as a whole
and only over the long run. Public safety also may require dedicated
spectrum to ensure priority access for emergency communications, though
the irregular spectrum demand of public safety users may allow for
additional users on a non-priority basis. Global satellite systems may
require globally harmonized spectrum to operate in. Importantly, the
Commission should recognize that many services will claim that they
warrant special consideration and thus deserve exemption from any reform
of their service allocation rules. It will be critical to distinguish
between special interest and the public interest, establishing a high
bar for any service to clear prior to receiving an exemption.

Therefore, the command-and-control model should be applied only in
special situations where prescribing spectrum use by regulation is
necessary to accomplish important public interest objectives or to
conform to treaty obligations. Examples may include achievement of
non-market public interest benefits (*e.g.,* radioastronomy) and
addressing policy objectives that the market fails to ensure, such as
those related to global harmonization of spectrum. Legacy
command-and-control bands should be transitioned to more flexible rules
and uses to the maximum extent possible, whether exclusive use or
commons model, with few exceptions.

The Report of the Spectrum Rights and Responsibilities Working Group
provides more detailed consideration of these issues.

**VI. Specific Recommendations**

After considering the issues and findings that have been presented
regarding the efficient access to and use of spectrum, the Working Group
makes a number of related recommendations. We believe these
recommendations should have a significant and positive impact on
efficiency. They also may affect interference and spectrum rights and
responsibilities issues, which are addressed in more detail in the
Report of the Spectrum Interference Working Group and the Report of the
Spectrum Rights and Responsibilities Working Group.

***Fostering technologies for uniform signal strength throughout a
service area.*** The Commission should ensure that its rules permit, and
when appropriate promote, the use of technologies that provide uniform
signal strength throughout a service area.

***Power limitations.*** The Commission should investigate rule changes
that enable the lowering of permitted power in urban areas and the
increasing of permitted power in rural areas. High-power broadcasters,
and other site-licensed services, should be permitted to convert to
lower power, multi-site transmission systems as long as their service
area is not expanded.

***Taking advantage of time***. The Commission should look at ways to
expand the use of trunking and other technologies that facilitate and
improve the sharing of spectrum between multiple users. The Commission
should also consider authorizing the use of spectrum with typically low
utilization by parties that are willing to operate on a interruption
basis (i.e., suspend their operations when the primary licensee is
transmitting).

***Taking advantage of space.*** The Commission should expand the
ability of licensees to partition their service areas so that others may
use the spectrum in places that the current licensee chooses not to
provide service. The Commission should also consider issuing "white
area" licenses that would permit new services to be offered in the
unserved areas between existing services.

***Permitting Other Users and Uses.*** The Commission should expand
access to secondary and unlicensed users. The Commission should expand
the opportunity for spectrum to be traded on the secondary market, so
that licensees can better match the amount of spectrum they have with
the amount that they need. The Commission should also permit broad,
highly flexible use within the necessary technical parameters of
existing (and future) allocations. Furthermore, the Commission should
permit traditionally narrow services, such as public safety, to lease
excess capacity to other non-related services. The Commission should
also permit services that may have a sporadic need for additional
spectrum to deal with peak situations, again such as public safety, to
reach voluntary agreements with other spectrum licensees to use
additional spectrum in such peak situations.

***Discouraging Inefficient Use.*** The Commission should consider user
fees or other steps, and seek necessary legislative changes, to provide
a stimulus for improving spectrum efficiency when the marketplace isn't
sufficient to do so. The Commission should promote a shift from
wireless-only systems to wireless/wireline hybrid systems, or even sole
wireline systems, whenever the spectrum is needed for higher valued use.
The Commission should consider setting receiver performance standards
whenever the marketplace isn't adequate in promoting a reasonable level
of interference tolerance (e.g., when receivers are not owned and
controlled by the licensee). The Commission should better define the
interference protection requirements and other expectations of
licensees. This should include investigating the feasibility of
establishing interference temperature thresholds for most parts of the
spectrum, regularly monitoring the noise floor, and over time adjusting
the Commission's interference temperature threshold as appropriate. The
Commission should promote the use of digital transmissions whenever
feasible. The Commission should review Broadcast rules that provide
separation criteria; many broadcasters believe that current receiver
technology allows for use of more channels in an area than current rules
provide especially because 70% of market uses cable.

***Grouping technically-compatible systems.*** The Commission should
look towards grouping allocations based on mutually-compatible technical
characteristics (such as power and sensitivity to interference). Over
time, the Commission should attempt to improve the out-of-band
interference performance of transmitters and receivers so as to reduce
the need for this kind of grouping.

***Adjusting Regulations as Technology Develops***. The Commission
should periodically assess the status of spectrum use, and make
adjustments to its regulations and policies to reflect changes in
priorities and capabilities of new technologies. The Commission should
continue to rely on Advisory Groups in this effort.

***Regulatory Models.*** The Commission should expand the use of both
the exclusive use and commons models, and move away from the
command-and-control model with limited exceptions. Specifically:

-   The exclusive rights model should be applied to significant parts of
    the spectrum, particularly in bands where scarcity is high and
    transaction costs are low. These conditions primarily exist below 5
    GHz, but may also occur in some higher frequency bands.

-   The commons model should be applied to significant portions of the
    spectrum, particularly in bands where scarcity is low and
    transaction costs are high. These conditions primarily exist in the
    higher microwave bands, particularly above 50 GHz, based on their
    limted propagation characteristics.

    -   Continuing and expanding the use of the commons model in some
        lower bands also is important to encourage the development of
        low power short distance communications and emerging
        technologies.

    -   The commons model also is appropriate for defining underlay
        rights.

-   The command-and-control model should be applied in special
    situations where prescribing spectrum use by regulation is necessary
    to accomplish important public interest objectives or to conform to
    international treaty obligations. Examples may include achievement
    of non-market public interest benefits (e.g. radioastronomy) and
    addressing policy objectives that the market fails to ensure, such
    as those related to global harmonization of spectrum which can be
    particularly important for global satellite systems.

-   Legacy command-and-control bands should be transitioned to more
    flexible rules and uses to the maximum extent possible, whether
    using the exclusive use or the commons model, with few exceptions.

# 

[^1]: *See* In the Matter of Principles for Reallocation of Spectrum to
    Encourage the Development of Telecommunications Technologies for the
    New Millennium, *Policy Statement*, 14 FCC Rcd 19868, ¶2 (1999)
    (*Spectrum Policy Statement*).

[^2]: *See* *Federal Communications Commission Strategic Plan FY 2003-FY
    2008*, available at
    <http://www.fcc.gov/omd/strategicplan/strategicplan2003-2008.pdf>.

[^3]: *See* PART-15 Organization Comments, at 1, which indicate that
    there are approximately 8,000 wireless internet service providers in
    the United States, and that there are likely to be over one million
    wireless internet users by the end of this year. XM Radio, a
    satellite radio broadcasting service, attracted 201,500 total
    subscribers in its first year of operation. *See* *XM Hits
    200,000+Subscriber Third Quarter Target*, XM Satellite Radio News
    Release, October 1, 2002, available at
    <http://www.xmradio.com/newsroom/screen/pr_2002_10_01.html>.

[^4]: For example, commercial mobile radio service subscribers grew from
    48.7 million to 134.6 million in the five-year period ending June
    2002. *See* *Cellular Telephone and Internet Association (CTIA)
    Semi-Annual Wireless Industry Survey*, available at
    <http://www.wow-com.com/industry/stats/surveys/>.

[^5]: *See* *Public Notice*, ET Docket No. 02-135, released June 6,
    2002, at 5.

[^6]: [The Random House College Dictionary]{.underline}, copyright 1973,
    by Random House, Inc.

[^7]: Broadcast television can transmit information to large numbers of
    people using a single transmitter, while mobile telephony requires
    lots of transmitters to reach the same number of people. Public
    safety provides information only to a limited number of public
    safety officials.

[^8]: *See generally*, 47 C.F.R. 1.2110. *See, e.g.*, DA 97-81, Public
    Notice announcing winners in D, E, and F blocks of PCS auction, with
    many Designated Entities receiving licenses (1997).

[^9]: This is similar to the definition in the International
    Telecommunication Union (ITU) Radiocommunication *Recommendation on
    Definition of Spectrum Use and Efficiency of a Radio System*, ITU-R
    SM.1046-1, available from the ITU at
    [www.itu.org](http://www.itu.org/).

[^10]: For example, a transmission consisting of very high speed coding
    of a voice signal might result in more information (i.e., bits)
    transmitted than a normal voice signal, but is the higher coding
    really better if a lower speed coding still provides a clearly
    usable transmission?

[^11]: *See* IEEE 802 Comments at 20.

[^12]: *See* ArrayComm, Inc. Comments at 11,12

[^13]: *See* XtremeSpectrum Comments at 11.

[^14]: In this section, the term "public sector" will be used to imply
    all spectrum use by local, state, and Federal Government agencies
    encompassing law enforcement, emergency services, general government
    and military use and spanning the jurisdiction of both FCC and NTIA.

[^15]: The addresses of the measurement locations are: Atlanta - 3575
    Koger Blvd, Duluth GA; New Orleans - 2424 Edenborn Avenue, Metairie
    LA; and San Diego - 4542 Ruffner Street, San Diego CA

[^16]: For this data, observations were made every 10 kHz.

[^17]: There are presently insufficient data to generalize these
    observations to all frequencies or to all locations.

[^18]: The Federal Government uses spectrum for both military and civil
    government purposes, and controls and shares a large fraction of the
    spectrum below 3 GHz. Federal Government frequency assignments made
    by NTIA are generally classified information and are not available
    to entities outside of the Federal Government.

[^19]: An example of such a high value use is a dispatch message to send
    a medic to resuscitate an individual who has stopped breathing.

[^20]: Statewide Wireless Network, New York State Office for Technology
    Comments, Docket 02-135 (July 8, 2002).

[^21]: *See* Ryszard Syski, *Introduction to Congestion Theory in
    Telephone Systems*, North Holland, 2^nd^ Ed. 1986.

[^22]: Data provided by Sean O\'Hara, Syracuse Research Corporation -
    Systems Technology Center, 9/17/02.

[^23]: Mathematically, the time constant of a change is the amount of
    time it takes for the quantity to change by a factor of 2.7.

[^24]: Capacity is generally related to the signal bandwidth multiplied
    by the signal-to-noise ratio. If the interfering noise is reduced,
    the signal-to-noise ratio and capacity are increased.

[^25]: *See*, for example, 47 C.F.R. 22.948, which permits partitioning
    and disaggregation in the Cellular Radiotelephone Service.

[^26]: *See, e.g.,* HYPRES, Inc. Comments at 5, Jon M. Peha Comments at
    8, Personal Telecommunications Technologies Comments at 2, and
    Mantuska Telephone Association Comments at 4.

[^27]: *See, e.g.,* Information Technology Industry Counsel Comments at
    8 and CDMA Development Group Comments at 7-8

[^28]: *See* Sprint Comments at 21 and Rural Telecommunications Group
    Comments at 8-9.

[^29]: *See, e.g.,* Wayne Longman Comments at 10, Citizens Media Corp.
    Comments at 14, Dandin Group Comments at 4-6, and John Martoccio
    Comments at 1.

[^30]: *See* In the Matter of Promoting Efficient Use of Spectrum
    Through Elimination of Barriers to the Development of Secondary
    Markets, *Notice of Proposed Rule Making*, WT Docket No. 00-230, 15
    FCC Rcd 24203 (2000).

[^31]: *See, e.g.,* Cantor Fitzgerald Telecom Services, LLC Comments at
    3, Catholic Television Network Comments at 3-4, David Rhodes
    Comments at 2-3, Ericsson Comments at 3, Comsearch Comments at 6,
    Blooston Mordkofsky Comments at 6, Rural Telecommunications Group
    Comments at 8-9, and Winstar Comments at 10.

[^32]: *See* FCC website, <http://www.fcc.gov/connectglobe/sec7.html>.

[^33]: *See, e.g.,* CTIA Summary Comments at 6. These licensees include
    most public safety users, non-commercial/educational entities, CMRS
    spectrum lottery winners, broadcasters, certain satellite system
    operators, and U.S. government users.

[^34]: *See* IEEE Comments at Question 22.

[^35]: Charles Trimble, Public Workshop on Spectrum Efficiency, August
    5, 2002.

[^36]: David Warner, Commonwealth of Virginia, Public Workshop on
    Spectrum Efficiency, August 5, 2002.

[^37]: *See* Thomas B. H. Kuiper Comments at Question 21.

[^38]: Paul Rinaldo, Public Workshop on Spectrum Efficiency, August 5,
    2002.

[^39]: Stephen Blust, Public Workshop on Spectrum Efficiency, August 5,
    2002.

[^40]: Adam Spitzer, Telecom Filings, Public Workshop on Spectrum
    Efficiency, August 5, 2002.

[^41]: S. Merrill Weiss, Paul Fox (Consultant), Carl Stevenson, Public
    Workshop on Spectrum Efficiency, August 5, 2002

[^42]: *See* CTIA Comments at 37

[^43]: Charles Trimble, S. Merrill Weiss, Ulrich Rohde, Steve Gillig,
    Marc Goldberg (ArrayComm), Public Workshop on Spectrum Efficiency,
    August 5, 2002.

[^44]: "Front end" is the frequency bandwidth that the receiver is able
    to receive at one time. Doppler shift is based on the Doppler effect
    -- "a change in the frequency with which waves from a given source
    reach an observer when the source and the observer are in rapid
    motion with respect to each other so that the frequency increases or
    decreases according to the speed at which the distance is decreasing
    or increasing." [Webster's New Collegiate Dictionary]{.underline},
    copyright 1979 by G. & C. Merriam Co.

[^45]: *See* Thomas B. H. Kuiper, Comments at Question 19.

[^46]: S. Merrill Weiss, Public Workshop on Spectrum Efficiency, August
    5, 2002. This "taboo" problem largely disappears for digital
    television (DTV) receivers.

[^47]: Generally, radio transmissions are able to communicate only if
    there is an adequate ratio of desired signal to undesired radio
    noise. Different radio technologies require different signal to
    noise levels to function.

[^48]: In digital television, for example, generally interference either
    occurs (and the television signal is completely lost) or it does not
    occur. In analog television, there is often a gradual decay in the
    quality of the received television signal as interference increased.
    This gradual decay is often difficult to predict, and is subject to
    very subjective assessments of when interference is harmful or
    significant, and when it is not.

[^49]: *See* Thomas W. Hazlett (Hazlett) Reply Comments at 2.

[^50]: *See* Cisco Systems, Inc. Comments at 8.

[^51]: *See* Fixed Wireless Communications Coalition Comments at 2.

[^52]: *See* AT&T Wireless Ex Parte Comments at 3-5.

[^53]: *See* AT&T Wireless Ex Parte Comments at 9-10.

[^54]: *See* AT&T Wireless Ex Parte Comments at 10.

[^55]: CTIA Comments at ii, 6-9.

[^56]: CDMA Development Group Comments at 7.

[^57]: Satellite Industry Association Comments (SIA) at 15.

[^58]: SIA Comments at 14. SIA also asserts that "There is a tradeoff
    between efficiency and robustness. Consumers and ... system
    operators are best suited to make this tradeoff. \[However,\] Public
    safety \[licensees\] face weaker incentives to adopt the most
    spectrum efficient technologies, so it may be appropriate to impose
    spectral efficiency requirements \[on such licensees.\]" SIA
    Comments at 14.

[^59]: Further Recommendations for adoption of regulations as technology
    develops are detailed in Section VI (Specific Recommendations).

[^60]: ITI Comments at 2-3.

[^61]: *See generally* Gerald R. Faulhaber and David J. Farber
    (Faulhaber and Farber) Comments; Hazlett Reply Comments; Statements
    of Thomas Krattenmaker and Peter Pitsch at the August 9, 2002 Public
    Workshop on Spectrum Rights and Responsibilities (*Public Workshop
    on Spectrum Rights and Responsibilities*).

[^62]: *See, e.g.,* New America Foundation et al Reply Comments; APCO
    Comments at 3; Statements of Ron Haraseth and David Warner at the
    August 5, 2002 Public Workshop on Spectrum Efficiency (*Public
    Workshop on Spectrum Efficiency*); *see also* SIA Comments at 4, 18;
    Bergen County Comments at 1-5; Private Radio Comments at 2; AIRINC
    Comments at 2; National Radio Astronomy Observatory Comments; Boeing
    Comments at 8, 9-10.

[^63]: *See, e.g.*, Gerald R. Faulhaber and David J. Farber (Faulhaber
    and Farber) Comments; Hazlett Reply Comments.

[^64]: *See, e.g.*, Kevin Werbach Comments; David Reed Comments

[^65]: *See, e.g.*, Statements of David Siddall and Michael Kurtis at
    the *Public Workshop on Spectrum Rights and Responsibilities*;
    Motorola Comments at 8; Information Technology Industry Council
    Comments at 3.

[^66]: *See, e.g.,* Faulhaber and Farber Comments; Hazlett Reply
    Comments.

[^67]: *See* *Spectrum Policy Statement*, *supra,* at ¶ 9; Principles
    for Promoting the Efficient Use of Spectrum by Encouraging the
    Development of Secondary Markets, *Policy Statement*, 15 FCC Rcd
    24178, 24180, ¶ 8 (2000); s*ee* *also, e.g.,* Flexibility for
    Delivery of Communications by Mobile Satellite Service Providers in
    the 2 GHz Band, the L-Band, and the 1.6/2.4 GHz Band; Amendment of
    Section 2.106 of the Commission's Rules to Allocate Spectrum at 2
    GHz for use by Mobile Satellite Service, IB Docket No. 01-185, ET
    Docket No. 95-18, *Notice of Proposed Rulemaking*, 16 FCC Rcd 15532,
    15533, ¶ 2 (2001) (*Flexibility Notice*) ("Flexibility has been the
    Commission's favored approach to spectrum management and licensing
    in recent years.").

[^68]: *Spectrum Policy Statement*, *supra*, at ¶ 9.

[^69]: *Spectrum Policy Statement*, *id.*

[^70]: *See* Amendment of the U.S. Table of Frequency Allocations to
    Designate the 2500-2520/2670-2690 MHz Frequency Bands for the
    Mobile-Satellite Service, First Report and Order and Memorandum
    Opinion and Order, 16 FCC Rcd 17222, 17223, ¶ 2 (2001).