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| A Note from the Publisher:
Last year Bennet & Bennet, PLLC brought in a team of skilled technical consultants
to help its attorneys better represent its rural telecommunications client base.
This new team of radio frequency and electrical engineers has been assisting B&B’s
clients and attorneys through their thorough knowledge of radio frequency design,
frequency coordination, technical contract review, preparation of vendor requests
for proposals, technical support, technical analysis, and regulatory mandates
such as E911. Having this new technical team on board at a time when many of our
clients are being presented with an ever growing list of wireless opportunities
made us stop and think, “How can we best share our newly acquired resources with
our clients and colleagues?” After a little brainstorming, we decided that the
success we have enjoyed with our legal and regulatory electronic publication,
Rural Spectrum Scanner , now in its eleventh year, could be built upon with the launch of a new electronic
quarterly e-publication entitled Rural Signals. Rural Signals will be delivered by e-mail four times a year (Spring, Summer, Fall and Winter)
and will feature technical discussions on current spectrum related happenings
and other technical telecom issues that affect rural America.
In this inaugural issue of Rural Signals , our team of technical consultants tackles a host of issues regarding the 700
MHz band in a friendly Q & A format. A technical side bar on the impact of
the incumbent television broadcast licensees’ signal contours on the 700 MHz licensees
also introduces the technical rules for getting along with television broadcasters
prior to their permanent relocation to their digital-only channels.
In an article on a microwave back haul vendor, Rural Signals Editor, Jim Egyud, examines the pros and cons of the use of smaller microwave
antennas in the 11 GHz band and the interference implications of using such devices
should the FCC grant the manufacturer, FiberTower, a waiver of its rules.
On the wireless broadband front, Rural Signals features an article on the restructuring of the Multichannel Multipoint Distribution
Service and the impact on rural carriers. This is also tied to another article
on the technical change in the Advanced Wireless Services band plan. AWS is being
hawked as the broadband data solution for cellular and PCS carriers. These two
articles are related because a portion of the MMDS spectrum is being reallocated
to AWS, and there is an interesting impact from the perspective of those operating
in rural America.
With so much spectrum reassignment activity, and with interference control and
management playing a significant role, Rural Signals also offers a discussion of the Interference Temperature concept contemplated
by the FCC as a means of sharing bandwidth.
On the Fixed Wireless front, Rural Signals contains an invitation to attend a trial featuring the broadcast of live video
footage of the inaugural Ironman Arizona triathlon race on April 9 utilizing WipLL
products over Ironmanlive.com. Technology from Intel and Airspan will be featured
in the trial, and Rural Signals will feature in-depth coverage in its upcoming Summer issue.
Enjoy Rural Signals and, as always, your feedback is priceless.
Bennet & Bennet, PLLC |
| Lower 700 MHz C-Block Springs to Life FAQs on Getting Started |
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By Len Garavalia
As activity in the Lower 700 MHz band springs to life, rural license holders
are coming forward and asking: "How do I get started?" This band offers a wealth
of possibilities, particularly for data offerings, but there is much to ponder
when it comes to converting a license to revenue when incumbent broadcasters occupy
the spectrum. Fittingly enough, with the first issue of Rural Signals , we have decided to focus on the 700 MHz "lamb" and address a few frequently
asked and important questions we have been getting concerning rural deployment
in the 700 MHz band.
- What is "short-spaced"?
One of the biggest potential impediments to the deployment of service in the
Lower 700 MHz band is the possibility of causing interference to incumbent broadcast
licensees. The FCC has designated various Private Radio and Broadcast standards
within FCC Rule Part 27 for licensees to determine whether they are "short-spaced",
that is, whether the applicant's facility is closer than the FCC's minimum distance
to an affected TV or DTV station. Following are links to Tables B, D & E within
the Private Radio rules, which identify the minimum distances.
- Table B - Co-channel base station separation distance is based on its maximum Effective
Radiated Power (ERP) and its average Height Above Average Terrain (HAAT). Just
like in the cellular world, average HAAT is based on average terrain elevations
two to ten miles from the base station in eight principal directions.
- Table D - For co-channel mobiles, the separation distance to the base station associated
with mobiles is based on the mobile ERP.
- Table E - Adjacent-channel base station separation limits are based on maximum ERP and
average HAAT for the proposed base station.
- Do I need a waiver?
The FCC has given some guidance, but has reserved the right to make an official
decision based on the unique characteristics of each applicant's market conditions.
Generally, under the following guidelines, no waiver is required if:
- The 700 MHz station facilities are not short-spaced. In this case, no FCC Form
601 application is needed (unless otherwise required by conditions such as an
Environmental Analysis for new tower construction, etc.).
- The 700 MHz licensee is short-spaced but meets the Desired-to-Undesired Signal
(D/U) ratio for the theoretical coverage contours (that is, the area defined by
the FCC as a station's protected coverage area). In this case, an engineering
justification must be filed with an FCC Form 601 application.
- The 700 MHz licensee is short-spaced but has received written consent from the
affected co-channel and adjacent-channel TV/DTV Broadcasters. In this case, the
consent agreements along with a description of the proposal with as much detail
as possible must be filed with an FCC Form 601 application.
A waiver will be required if:
- The 700 MHz licensee is short-spaced and does not meet the D/U ratio for the
theoretical coverage contours. As is the case for a short-spaced licensee that
meets the D/U ratio, an engineering justification must be filed with an FCC Form
601 application.
For more information on D/U Ratios and broadcast contours, please see the accompanying
Technical Note and the accompanying article by David Fritz: Another 700 MHz Question:
What Is the Broadcast Service Contour?
| Technical Note: A little more info on D/U Ratios |
D/U Ratios are defined by the FCC for:
- co-channel DTV stations as a minimum 23 dB D/U ratio required at the co-channel
DTV station's 41dBuV/m equivalent Grade B contour.
- adjacent-channel DTV stations as a minimum -23 dB D/U ratio (i.e., the undesired
signal can be stronger) required at the adjacent-channel DTV station's 41dBuV/m
equivalent Grade B contour.
- co-channel Analog TV stations as a minimum 40 dB D/U ratio required at the co-channel
TV station's 64dBuV/m hypothetical Grade B contour.
- adjacent-channel Analog TV stations as a minimum 0 dB D/U ratio required at the
adjacent-channel TV station's 64dBuV/m hypothetical Grade B contour.
|
- Who has requested 700 MHz waivers, and what is their status?
While there are Lower 700 MHz band licensees currently operating under Part 27
of the FCC Rules, here is a sample list of licensees that have requested waiver
of those rules or an experimental license in order to operate:
- Access Spectrum, LLC was granted a waiver last August to operate on its guard-band
channels (1 MHz pairs on lower Channels 60 and 65) at a location in Houston, Texas.
Access Spectrum proposed adjacent-channel operation with a Channel 61 broadcaster.
- Aloha Partners was granted a waiver on February 18, 2005 to operate on channels
54 and 59 in Tucson, Arizona. Only Aloha's proposed Channel 59 operation is co-channel
with an incumbent broadcaster.
- OCTO (Office of the Chief Technology Officer) in Washington, DC filed an application
for an experimental license to operate in Public Safety Spectrum on Channels 61
and 69 (short-spaced with Channel 62 WFPT). It received its grant in August 2004
and its progress report is due next month (Station WD2XHO).
- Qualcomm filed a Petition for Declaratory Ruling on January 10, 2005. To date,
the FCC has not acted upon it. We will discuss the subject of the petition, interference
protection metrics, later in this Q&A session.
These applications are important because their technical showings can serve as
a general guide, assuming the parameters for your deployment are essentially the
same as those previously granted.
- What if there are TV/DTV translators, boosters, or other low power stations located
on the C-Block frequencies in my market?
- The good news here is that the low power stations have secondary status to the
Lower 700 MHz C-Block licensed operations, but the FCC has specific rules outlined
for termination of the low power stations.
- The 700 MHz carrier must be prepared to show that the low power station would
interfere with the proposed operation.
- Termination notices should be provided to the incumbent low power station at
least 120 days prior to your scheduled in-service date.
- Caution: The secondary station could object to the termination, so be prepared
for this possibility.
- How can I deploy if there are existing broadcasters?
- Determine if there is one distinct, dominant interfering broadcaster affecting
your market or portions of your market. Then consider utilizing a vendor and technology
type that supports Time Division Duplexing (TDD) or half-duplexing. This allows
you to use either Channel 54 or 59 as both the uplink and the downlink.
- If both Channels 54 and 59 are affecting your market:
- Determine to what extent they will interfere with your proposed network and to
what extent your facilities will affect the reception of those broadcasters' signals
WITHIN THEIR PROTECTED GRADE B CONTOUR(S).
- Work with the unique terrain and morphology variations within your market, the
directionality of antenna systems, and the directionality of the broadcasters'
antenna systems.
- Consider a combination of 700 MHz and unlicensed facilities to work around the
broadcasters.
- Consider the broadcasters' targeted communities of service. Are there station
affiliates that serve your market on TV channels outside the 700 MHz band? Once
you have your engineering justification in order, coordinate directly with the
broadcasters.
- Consider actual measurements of the TV/DTV environment to justify your design
and interference analysis and to document the real-world implications for the
broadcasters and for a potential waiver application. Depending on your unique
market characteristics, this could be the first step to determine if your 700
MHz network impacts or is impacted by the incumbent TV/DTV broadcasters.
- In its petition for declaratory ruling, Qualcomm offered yet another solution.
Qualcomm believes that the FCC should declare that Office of Engineering and Technology
(OET) Bulletin 69 is an acceptable method of determining interference protection
for TV/DTV stations and complying with FCC Rule Section 27.60 protection criteria.
It believes the Commission should declare that interference to a threshold of
2% of the TV/DTV over-the-air viewing population is an acceptable de minimis standard.
(The term "de minimis" comes from the Part 73 Broadcast ruleswhich permit an interfering
broadcaster to affect up to 2% of an adjacent or co-channel station.)
- In some cases, there may be markets that simply cannot be served until the broadcasters
complete their transition.
- Is 12 MHz of spectrum enough?
- Typically, paired 6 MHz channels should be enough to begin operation and meet
initial demand; however…
- Check your radio access vendors' specifications for the number of subscribers
each RF channel can accommodate AND at what average data rate.
- Compare the bandwidth limits of each RF channel for that vendor to your spectrum
allocation and the technology's spectrum re-use limits.
- By comparison:
- Cellular spectrum uses paired 12.5 MHz bands, and carriers are struggling with
band-clearing for competing technologies (such as CDMA vs. GSM) in adjacent co-channel
markets. Therefore, many markets are being overlaid with 1900 MHz as a means to
add capacity.
- 1900 MHz Broadband PCS ranges from paired 5 MHz blocks (the D, E, and F blocks
on a BTA basis) to paired 15 MHz blocks (the A and B blocks on an MTA basis and
the C block on a BTA basis).
- Many broadband carriers are going further and supplementing their spectrum allocations
with portions of the other PCS blocks in paired segments as small as 2.5 MHz.
- For future subscriber capacity growth and for services that will demand higher
bandwidths (such as streaming media) or priority access (such as VoIP, VPN, or
Public Safety), the 12 MHz licenses may need to be supplemented.
We suggest that rural carriers work with their attorneys and/or industry associations
to petition the FCC to auction additional spectrum in the 700 MHz band that would
be licensed on an MSA and RSA basis.
- What is my build-out schedule?
What are the deployment ramifications with regards to the time period of your
license? For licensees that elect to commence new broadcast operations prior to
January 1, 2007, the renewal deadline will be set at the end of an eight-year
term following commencement of such broadcast operations. At the end of the eight-year
term, the license will be subject to Section 27.14 of the FCC rules as it relates
to Construction requirements. The rule states, in part, "...licensees must make
a showing of `substantial service' in their license area within the prescribed
license term.…" Initial authorizations for the 698-764 MHz and 776-794 MHz bands
will extend until January 1, 2015.
In other bands, such as PCS, the FCC has stated clear renewal requirements such
as coverage to 25, 30 or 60 percent of the market population. The FCC rules for
the Lower 700 MHz licensees do not specifically define "substantial service" at
this time. However, some flexibility has been built in where portions of your
market cannot be built out due to the potential for interference with incumbent
TV/DTV broadcasters.
******While there is not enough space in our first issue of Rural Signals to address all of the questions we receive concerning the 700 MHz band, this
article should have you thinking about some of the technical concerns related
to deploying in this band.
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Should you have any questions, please do not hesitate to contact Len Garavalia, Director - Technical Consulting Services. |
| back to top |
| Another 700 MHz Question: What Is The Broadcast Service Contour? |
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By David Fritz
Many licensees from Auctions 44 and 49 (the Lower 700 MHz C Band) come from commercial
fixed and mobile radio backgrounds (Cellular, Paging, etc.) and are looking to
continue their deployments by using 700 MHz with data services. They are not strangers
to FCC service contours (i.e., cellular's 39 dBu and 32 dBu; paging interference
and service contours; etc.). Such contours are based on mathematical formulas,
applied uniformly to all licenses, and clearly outlined in the FCC rules to approximate
or define service and/or interference boundaries with other licensees. Now armed
with a license in the UHF television band, these new licensees are getting a taste
of a different type of service contour: the broadcast Grade B Contour.
For analog TV stations, the service grade contours defined in the FCC rules,
as shown in Table 1 below, use field strength values in decibels above one micro-volt
per meter ("dBu") and represent the TV stations' theoretical coverage as recognized
by the FCC. While the FCC uses the Grade A and City Grade contours to represent
coverage, it uses the Grade B contour to represent a boundary for interference
protection. To predict the distance from the station to the analog field strength
contour, the FCC provides propagation curves that represent the estimated field
strength in dBu being exceeded at 50% of the potential receiver locations for
at least 50% of the time ("F(50,50)"), based on the transmitting antenna height
in meters. With the use of the F(50,50) field strength curve, the full analog
TV contour can be geographically produced by calculating the contour distances
using the transmitter's antenna Height Above Average Terrain ("HAAT") and Effective
Radiated Power ("ERP") for each of 360 evenly spaced radials extending from the
transmitter location, and connecting the end points of these distances. Obviously,
with the use of linear interpolation, less accurate approximations can be accomplished
with fewer radials. Essentially, the contour is a collection of points where the
calculated field strength meets or exceeds the FCC's threshold value for that
grade of service on that channel.
Table 1 - National Television System Committee (NTSC) Analog Television (Field
Strength Threshold):
| Channels |
Grade B
Service Contour |
Grade A
Service Contour |
City Grade
Service Contour |
| Channels 2-6 |
47 dBu |
68 dBu |
74 dBu |
| Channels 7-13 |
56 dBu |
71 dBu |
77 dBu |
| Channels 14-69 |
64 dBu |
74 dBu |
80 dBu |
Digital TV contours have their own set of values as outlined in the FCC Rules
(see Table 2 below). Service for Digital TV stations is defined to exist where
estimated field strength exceeds the threshold value at 50% of the potential receiver
locations for at least 90% of the time, F(50,90). Until recently, the FCC did
not produce F(50,90) field strength curves for direct calculation of digital TV
contour distances. To calculate the F(50,90) contour distance, the following formula
was developed in conjunction with the F(50,50) and F(50,10) field strength curves
found in the FCC regulations:
F(50,90)=F(50,50)-[ F(50,10)- F(50,50)]
As done to produce the analog TV contour, calculating and connecting the contour
distances for 360 evenly spaced radials around a transmitter location geographically
produces the Digital TV contour. For interference protection purposes, the DTV
Noise-Limited Service contour in Table 2 is digital TV's functional equivalent
to analog's Grade B contour.
Table 2 - Digital Television (Field Strength Threshold):
| Channels |
DTV Noise-Limited Service |
Minimum Field
Strength Over
Community of License
Prior to Dec. 31, 2004 |
Minimum Field Strength
Over Community of License After Dec. 31, 2004 (Commercial TV) or After Dec. 31,
2005 (Non-commercial Educational TV) |
| Channels 2-6 |
28 dBu |
28 dBu |
35 dBu |
| Channels 7-13 |
36 dBu |
36 dBu |
43 dBu |
| Channels 14-69 |
41 dBu |
41 dBu |
48 dBu |
Certainly, the service contours used by the incumbent analog and digital TV licensees
have many different values depending on the channel, service and type of technology.
The contours and FCC rules were formulated years ago for the incumbent broadcaster,
but were never refined for the new users of the spectrum. This quagmire has left
many new 700 MHz licensees knee deep in broadcast rules and service contours to
justify their deployment cases in areas where they find themselves close-spaced
with incumbent licensees. For others, it's just too much, so the decision is to
do nothing with their spectrum until their co-primary neighbors finally vacate.
******
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For more information on broadcast service contours or deployment challenges in
the 700MHz bands, please contact David Fritz. |
| back to top |
| FiberTower Proposes "At Your Own Risk" Licensing of Two-foot Antennas in the
11 GHz Band, Seeks FCC Waiver in the Meantime |
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By Jim Egyud
FiberTower, Inc., a vendor of network backhaul solutions, has filed a Rulemaking
Petition and a Waiver Request at the FCC that seeks an amendment of the FCC Rules
to permit the use of smaller, less-directional antennas in the 10.7-11.7 GHz Fixed
Service Band ("the 11 GHz band"). These filings recommend conditions under which
the smaller antennas would be permitted, including interference protection only
to the extent that it would be afforded to larger antennas that currently comply
with the FCC Rules. FiberTower asserts that the smaller antennas cost less and,
because of their smaller size, can be deployed on more structures than their larger
counterparts.
What the FCC Rules Say
The FCC Rules require certain electrical characteristics of microwave dishes
coordinated and used by applicants and licensees in the 11 GHz band. The idea
is to minimize interference potential through the use of narrow, focused radiation
patterns along the main direction or axis of transmission, and also through the
suppression of secondary pattern lobes away from the main axis (otherwise known
as "side-lobe suppression"). The ability to focus the radiation pattern depends
on the size, shape, and construction of the antenna. In the 11 GHz band, the FCC's
beamwidth, gain, and suppression requirements have not been met by antennas smaller
than four feet (1.22 meters) in diameter. It should be noted that the 11 GHz band
is also shared by satellite service licensees, whose terrestrial receivers are
afforded interference protection. For the terrestrial user, the 11 GHz band represents
an intermediate option for paths of a few miles in length.
FiberTower's FCC Wish List
In its Petition and Waiver Request, FiberTower contends that smaller antennas
may be easier to deploy in some circumstances, and might be the only option where
a supporting structure's capacity or space availability precludes a larger antenna
that meets the FCC's requirements. Moreover, the smaller antennas are less expensive
and less visually obtrusive, thereby more likely to gain support in zoning and
siting proceedings. FiberTower suggests that the ability to use such smaller antennas
will promote efficient use of the spectrum by allowing antennas to be placed at
locations where antenna placement might not have otherwise been possible.
The downside? Size matters, but it's the radiation pattern that counts. The smaller
antennas are more susceptible to interference both into and from co-channel facilities.
As a mitigating factor to existing paths, because the smaller antennas inherently
have less gain, they are more limited in the amount of power that they can transmit,
and would be usable only for the shortest of 11 GHz paths. On the flip side, the
receiving end of the path using a smaller antenna is more susceptible to interference
for two reasons: its weaker side-lobe suppression can pick up more off-axis interference,
and it would be receiving less of the desired signal because of the smaller antenna
transmitting to it.
Nonetheless, the Waiver Request offers a number of conditions designed to minimize
the potential interference issues inherent to the smaller antennas, the highlights
of which are:
- Conformance to technical specifications proposed in the Petition for such antennas;
- Compliance with the outcome of the Petition proceeding;
- Limited conditions under which a licensee or applicant using a two-foot antenna
under the waiver may object to a subsequent coordination by another carrier;
- Obligations of the licensee or prior applicant using the two-foot antenna to
reduce predicted interference resulting from a subsequent coordination from another
applicant using a larger (compliant) antenna; and
- FiberTower agrees to limit its installations under the waiver to 500 units per
year. (Since FiberTower structured the Waiver Request to apply only to facilities
that it sells to its customers, others seeking similar relief pending the outcome
of the Petition would have to file their own waiver requests.)
Regarding conditions (3) and (4), interference protection would be afforded to
the applicant/licensee using the two-foot antenna only to the extent that the
interference would still have occurred into a larger, compliant antenna, assuming
all else being equal. In condition (3), the coordinating party would then have
to protect the smaller antenna user only to the extent that it were protecting
the compliant antenna. In condition (4), the coordinating party would only be
able to require the two-foot antenna user to reduce predicted interference levels
to those that would have occurred from a larger, compliant antenna. To summarize,
in the coordination and licensing process, the Waiver Request and Petition would
essentially make these smaller, less-directional antennas akin to larger antennas
with Category B interference characteristics.
Summarizing the Pros and Cons
For those looking to construct 11 GHz paths, the Waiver Request and underlying
Petition would open a door to make deployment of short-haul facilities in tight
physical confines more feasible. For those that might be concerned about potential
interference between the less-directional antennas and their existing or prior
coordinated facilities, the proposed coordination and licensing methodology would
appear to afford ample protection on paper. However, the fact remains that the
smaller antennas, which do not have the narrower beamwidths and stronger side-lobe
suppression of their larger brethren, remain more susceptible to inducing or receiving
interference in certain instances. In the field, such interference sources can
be difficult to isolate. Therefore, great care must be taken during the coordination
process. If the Petition were to be granted, carriers seeking to deploy the smaller
antennas would be wise to prepare a backup plan in case interference issues arise
after deployment.
******
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Should you have any questions about the outcome of this Petition or desire more
information about this technology, please contact Jim Egyud, Senior Technical Consultant. |
| back to top |
| FCC Restructures MMDS into Educational Broadband Service, Broadband Radio Service
. . . and Cellular? |
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By Judy Deng
The FCC has announced a plan to reform the spectrum rules in the 2.5 - 2.7 GHz
MMDS/ITFS band in the Report and Order released on June 10, 2004, and there is
much to digest. MMDS (Multichannel Multipoint Distribution Service) is presently
used in the United States to deliver video program content for entertainment and
distance-learning activities. Most systems use analog transmission under the National
Television Systems Committee (NTSC) standard to deliver one video program per
6-MHz channel. The Order renames the MMDS service as the Broadband Radio Service
(BRS) and renames ITFS (Instructional Television Fixed Service) as the Educational
Broadband Service (EBS).
In restructuring these bands, the FCC takes a number of important steps to make
more efficient use of the spectrum as shown in the chart found here. The chart compares the current band plan to the post-transition plan as adopted
by the FCC.
The Skinny: Wider Band Segments
The Order eliminates the use of smaller, interleaved channels by BRS and EBS
licensees and creates a distinct band segment for high power operations flanked
by band segments created for low power operations. The three aptly-named segments,
the Lower Band Segment (LBS), the Middle Band Segment (MBS), and the Upper Band
Segment (UBS), are separated by 4 MHz guard bands. The low power channel blocks
in the LBS and UBS segments consist of four 16.5 MHz bands, each with three (3)
5.5 MHz channels. The MBS consists of eight 6 MHz channels. Five of the eight
6 MHz channels are allocated to EBS, and two are allocated to BRS. Again, these
channels are consistent with the NTSC channel bandwidth and are allowed to use
high power for the delivery of video. (In addition, the FCC reallocated MDS Channels
1 and 2 to BRS 1 and 2, respectively.) Sorting it all out, the FCC has created
larger and potentially more usable chunks out of the same spectrum.
While there are several ramifications to the restructuring, three specifically
stand out. First, the new band plan reduces the likelihood of interference caused
by incompatible technologies vying for the same spectrum. Second, and perhaps
more intriguingly, the restructuring creates incentives for the development of
low power, cellular-type broadband operations, which were limited by the prior
interleaved band plan. Third, existing licensees currently using the band for
high-powered video service will likely face additional challenges should they
desire to continue to provide video services following the EBS/BRS transition.
Obviously, there are many issues that licensees and prospective carriers will
have to sort out, including the territorial aspects of interference protection.
Look for Rural Signals to address more of this potential treasure trove of rural spectrum opportunities
in the next issue.
******
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If you would like to know more about the restructuring of the MMDS band, please
contact Judy Deng, Technical Consultant. |
| back to top |
| T-Mobile and RTG Join Forces to Bring AWS to Rural America |
|
By Len Garavalia
T-Mobile USA, Inc. ("T-Mobile") and the Rural Telecommunications Group, Inc.
("RTG"), a trade association made up of small and rural wireless telecom companies
( www.ruraltelecomgroup.org), recently came together to encourage the FCC to revise its band plan for Advanced
Wireless Services ("AWS") in the 1.7 GHz and 2.1 GHz Bands. T-Mobile and RTG recommended
that the FCC reconfigure its current 30 MHz E Block to add spectrum to the D Block,
and create a sixth AWS license block. This would create a total of 20 MHz of paired
spectrum for use within the RSAs and MSAs; no license would consist of more than
20 MHz of spectrum; and no less than 20 MHz of spectrum would remain in each of
the three market categories: Economic Area (EA), Regional Economic Area Groups
(REAG), and Metropolitan Statistical Area/Rural Service Area (MSA/RSA).
T-Mobile's and RTG's plan to reconfigure the AWS band would allow small rural
carriers operating in the RSAs to acquire affordable spectrum to augment their
existing services and remain competitive with larger regional carriers, while
ensuring that national, regional and local licensees would not be forced to acquire
more spectrum than needed. Under the joint plan, those carriers seeking to acquire
additional spectrum can simply aggregate more licenses.
Specifically, T-Mobile and RTG propose the following band plan:
| Block |
MHz |
Pairings |
Area |
Licenses |
| A |
20 |
1710-1720 paired with 2110-2120 MHz |
EA |
176 |
| B |
20 |
1720-1730 paired with 2120-2130 MHz |
REAG |
12 |
| C |
10 |
1730-1735 paired with 2130-2135 MHz |
REAG |
12 |
| D |
20 |
1735-1745 paired with 2135-2145 MHz |
MSA/RSA |
734 |
| E |
10 |
1745-1750 paired with 2145-2150 MHz |
EA |
176 |
| F |
10 |
1750-1755 paired with 2150-2155 MHz |
REAG |
12 |
RTG encouraged the dedication of 20 MHz of paired spectrum for MSAs/RSAs in the
D-Block so that rural licensees would have a competitive share of the spectrum
comparable to the licensees in the other blocks. In addition, BRS channels 1 &
2 encumber the F-block frequencies from 2150-2162 MHz. This is important because,
while there are other unencumbered REAG licenses proposed, there is only one MSA/RSA
license block proposed. If the MSA/RSA license were to remain in the F-block,
the upper pairing would remain unavailable for rural broadband deployment.
If accepted by the Commission, the joint AWS band plan will promote flexible
spectrum policy and competitive opportunities in all areas of the country, bringing
AWS to urban areas as well as rural and underserved areas.
******
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For more information about the joint AWS plan, please contact Len Garavalia, Director, Technical Consulting Services. |
| back to top |
| Taking Temperatures: A Concept For Interference Management |
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By Malick Sohrab
As the United States moves to becoming a wireless society, the FCC has been trying
all sorts of ways to free up more spectrum. One controversial school of thought
that has gained notoriety is a temperature-based methodology that would allow
the monitoring and management of interference between devices that operate within
licensed and unlicensed bands. In a Notice of Proposed Rule Making, the FCC floated
the idea of an interference measurement and quantification matrix called "Interference
Temperature". Measured in Kelvin(s) [K], this quantity is a temperature equivalent
of the amount of noise and interference in a specific frequency band, obtained
by taking the power in the band measured in Watts [W], and dividing it by the
RF bandwidth (in Hz) and the Boltzman constant (in W-sec/K). The result would
theoretically quantify in Kelvin (and hence temperature) the noise/interference
density per Hz at a location and within a specific frequency band.
The idea is that unlicensed devices that could measure such a "temperature" in
a certain licensed band would conceptually power up to within a certain interference
threshold, which remains below the minimum operating noise floor requirements
of the licensed entities' equipment. Theoretically, the unlicensed device should
remain unnoticed by the licensed entity's equipment. The "minimum operating noise
floor requirement" is the key here in that the FCC proposes to set a cap on the
interference that a licensed entity would experience within its band. This would
allow unlicensed users in the same band to operate so long as they do not exceed
the cap. This would, in essence, protect the licensed entity while allowing additional
use of the same spectrum.
Although the FCC's proposal gets more complicated in proposing numerous methods
to aid the real time measurement and management of the interference to the licensed
user, the core concept behind the idea is tied to the RF engineering concept that
radio devices, especially those in the broadcast environment, are typically engineered
to function with respect to certain noise floor requirements. As long as other
devices are able to establish that they can operate in the same band without degrading
the noise floor requirements of the licensed user, there should conceptually be
no interference problems.
As a potential application of this concept, one could consider the 700 MHz TV
band, which has been opened up for use to potential broadband data and other wireless
services. In concept, operating co-channel with certain TV stations within this
band would typically raise the eyebrows of those thinking that the TV receivers
in the area would receive additional interference that degrades reception. However,
TV station bandwidths are typically 6 MHz wide, and the operating interference
thresholds for the TV channels are based on this 6 MHz bandwidth. Existing and
evolving wireless broadband data technologies that use bandwidths narrower than
6 MHz (e.g., 1.25 MHz) would conceptually introduce interference to the TV broadcast
within a narrower segment of the larger 6 MHz TV carrier. Using the Interference
Temperature concept, if judiciously positioned within the TV carrier's channel,
the wireless data carrier could raise the TV broadcast noise floor environment
only marginally to where the effective noise floor remains below what would adversely
affect the TV receiver. Of course, this application also assumes that the incoming
broadband technology inserted within the TV channel can itself operate properly
with the reciprocal noise/interference from the TV signals.
Spread spectrum technologies such as CDMA and OFDM that would operate with bandwidths
(e.g., 1.25 MHz) narrower than a TV channel, and below the noise floor in the
environment, may be able to do so when engineered appropriately. However, equipment
specifications and technology variations among vendors manufacturing this equipment
must be scrutinized to ascertain that the viability of the resulting engineering
design is practical and achievable both technically and monetarily.
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Rural Signals will continue to keep an eye on the proposed use of interference temperature
for the management of spectrum and let our readership know if anything starts
to "heat up". In the interim, please contact Malick Sohrab should you have any questions. |
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| Ironmlive.com to use Wireless to Broadcast Ironman Arizona Race |
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By David Fritz
Ironmanlive.com, Intel, Airspan and Bennet & Bennet, PLLC have teamed together
to utilize wireless technology to broadcast live video coverage of the inaugural
Ironman Arizona triathlon on Saturday, April 9 in Tempe, Arizona.
Airspan, in collaboration with Intel, Ironmanlive.com and Bennet & Bennet,
PLLC, will be deploying a demonstration of Airspan's WipLL product line. Airspan's
WipLL product is a low-cost, high performance Fixed Wireless Access system that
can be used to deliver high-speed data services to remote locations. The WipLL
product is available in licensed bands of 700 MHz, 2.5 GHz, 2.7-2.9 GHz and 3.4-3.8
GHz and unlicensed bands of 900 MHz, 2.4 GHz and 5.8 GHz. With burst speeds up
to 4 Mbps (3.2 Mbps -net), the WipLL product line has a wide range of potential
for rural applications and quick deployments.
The Ironman Arizona demonstration deployment will feature the WipLL product as
the air interface between Ironmanlive.com's production facilities and remote full
motion video cameras along the swim, bike, and run course. System deployment will
be done the day before the race, and tours of the deployment will be done after
setup and during race day where access is available. To watch the live broadcast
of the race, tune into www.ironmanlive.com beginning at 7:00 am Pacific Time on April 9.
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Rural Signals will report on the outcome of the demonstration in its summer issue. If you
are interested in attending the demonstration or would like more information on
this wireless technology, please contact David Fritz. |
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If you have come across Rural Signals on-line and do not already receive our free quarterly e-mailed version, simply
e-mail the Editor, Jim Egyud, by clicking here. Thank you for your interest.
Questions??? Call Rural Signals Editor Jim Egyud [(202) 371-1500], and refer to Vol. 1, No. 1.
About Rural SignalsRural Signals is a quarterly publication of Bennet & Bennet, PLLC's technical consulting
service division. Rural Signals is delivered by e-mail four times a year and features technical discussions
on current spectrum related happenings affecting rural America. For subscription
information or to inquire about specific rural spectrum issues, please call/fax/e-mail
Rural Signals Editor Jim Egyud at 202-371-1500 or 202-371-1558 (fax).
While it is our intention to provide valuable information to readers of Rural Signals , the transmission of this newsletter does not create an attorney-client relationship.
You should not act upon any information contained in Rural Signals or at www.bennetlaw.com without first seeking the advice of an attorney.
Copyright 2005 Bennet & Bennet, PLLC
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