HomeMy WebLinkAboutSP199600004 Presentation Special Use Permit 1996-05-07 DENNY & ASSOCIATES, P.C.
CONSULTING ENGINEERS
WASHINGTON, DC
ENGINEERING EXHIBIT
PREPARED ON BEHALF OF
360° COMMUNICATIONS COMPANY
IN SUPPORT OF APPLICATIONS
SP-96-03 (HICKORY SITE)AND
SP-96-04 (AVON SITE)
ALBEMARLE COUNTY,VIRGINIA
ENGINEERING STATEMENT
INTRODUCTION
Alan R. Rosner,being first duly sworn, says that he is a senior engineer with
Denny & Associates, P.C., consulting engineers with offices in Washington, D.C.; that
he is a professional engineer registered in the District of Columbia and other
jurisdictions; that his qualifications are a matter of record with the Federal
Communications Commission; and that he is familiar with communications systems of
the type described herein. This statement has been prepared for 360° Communications
Company (hereinafter, 360° Communications), proponent for the construction of two
new cellular base stations' facilities in Albemarle County, Virginia. These sites are
referred to herein as the Hickory and Avon sites. This statement addresses the
necessity of these sites for specific reasons of a scientific and engineering nature.'
BACKGROUND
Cellular telephones operate in the 869-to-894 megahertz portion of the ultra-
high frequency (UHF) band. Communications in the UHF band principally occur over
a line-of-sight path between the transmitter and receiver. Radio signals are
transmitted from antennas located on 360° Communications's tower at relatively low
This analysis is based on specifications for the proposed and existing facilities
provided to the undersigned by 360° Communications Company.
DENNY & ASSOCIATES, P.C.
CONSULTING ENGINEERS
WASHINGTON, DC
Engineering Statement Page 2
Albemarle County,Virginia
power levels of 100 watts per channel. Mobile cellular telephones, which send signals
from vehicles to the cellular site receivers, transmit with 3 watts of power, and portable
or hand-held phone units transmit with only 0.6 watt of power. Add-on antenna
products which claim to increase the range of portable hand-held phones are not
capable of increasing the phones output power to that of mobile units.
Typical coverage areas for cellular base station facilities vary greatly but
generally range from 2 to 10 miles. Two of the greatest factors affecting UHF signal
propagation are diffraction and foliage. Diffraction describes the redirection of radio
waves caused by obstructions in the path between a transmitter and a receiver. These
obstructions can be natural terrain features as well as man-made structures.
Diffraction decreases or attenuates the strength of a signal. In extreme cases,
attenuation due to diffraction can reduce signal strength below a usable level. Foliage
also attenuates UHF signal strength. In comparison to an unobstructed line-of-sight
path which would present a predictable attenuation, signal attenuation at UHF
frequencies due to foliage can be over 1,000 times greater than expected over an ideal
path. Stated differently, UHF signal strength may be 1,000 times greater with an
unobstructed line-of-sight signal path than it would be when the path is obstructed by
heavy foliage. Diffraction and foliage losses present a particular challenge to reliable
cellular transmission because of the low transmitter power levels used in the cellular
service. These UHF propagation limitations are not a factor for the comparatively low
frequency(0.5-30 megahertz) transmissions of AM radio stations, which broadcast with
power levels up to 50,000 watts, and high frequency (HF) amateur radio stations, which
operate at power levels up to 1,500 watts.
For the reasons given above, UHF transmitting and receiving antennas
should be mounted at minimum heights which are as far above ground level as
DENNY & ASSOCIATES, P.C.
CONSULTING ENGINEERS
WASHINGTON, DC
Engineering Statement Page 3
Albemarle County,Virginia
necessary to achieve a line-of-sight path. As a practical matter, the mobile or portable
cellular telephone antenna height is limited to a few feet, so the only variable left to
adjust in achieving the desired line-of-sight path is the cellular base station antenna
height. 360°Communications has specified overall antenna height to clear the existing
tree line, allow for future vegetative growth, and to provide as much as possible a
line-of-sight path to the intended service area.
To effectively design cellular systems, engineers utilize computer modeling
techniques to estimate coverage. Propagation studies or scatter plots of the type
included in Figure 1 and Figures 3 through 6 of this exhibit, are one type of computer
modeling used by cellular telephone companies and communications engineers to
predict cellular telephone coverage. These studies are based on propagation models
which take into account the most predominant factors relating to coverage for a
particular site including location, terrain, climate and, to some degree, vegetation. The
use of highly specialized propagation models is a common and accepted practice of
engineers in the design of complex communications systems. The predictability and
reliability of these propagation models are typically very high. Propagation, or the
traveling of a wave through any medium, is affected by so many factors that signal
strength is expressed as a function of statistical probabilities. These probabilities are
typically expressed relative to variances in the signal strength over time and location.
Generally, the farther the location from the transmitter, the greater the degree of signal
variance, and the less accurate the prediction. Since computer studies like those
provided by 360° Communications cannot account for all of the factors affecting
propagation, they should be viewed only with the purpose they are intended: as an
engineering guide for site selection and coverage determination.
DENNY & ASSOCIATES, P.C.
CONSULTING ENGINEERS
WASHINGTON, DC
Engineering Statement Page 4
Albemarle County, Virginia
While propagation studies are extremely useful tools for predicting potential
coverage, actual measurement data provide much more reliable information on where
coverage needs to be improved and provide engineering validity to customer complaints
about service. Since signal propagation is based on statistical probabilities,
measurement data must account for these statistical factors. In a mobile environment,
the dominant statistical factor is location and second to location is time. Proper field
strength measurements are made with a calibrated system, often computerized, which
enumerates the mean field strength of numerous locations over a short distance
segment. It is inadequate to go to a single location and make a measurement or
demonstrate that a call can be placed since this fails to account for variations in time
and location.
Sometimes modifications to cellular systems are necessary to meet increased
customer demand. Few options exist for a cellular provider needing to increase channel
capacity. Generally the simplest option is to increase the number of channels at the
cellular base station sites which serve the affected area to the maximum. However,
cellular licensees only have a finite number of channels that they may use within their
service area. In the instant case, the number is 38 voice channels. This corresponds
to a maximum of 38 simultaneous telephone conversations at each site. To provide
service over their entire licensed service area, given the limited number of channels,
cellular providers must reuse frequencies. Careful spectrum planning and engineering
insure that sites sharing the same frequencies or adjacent frequencies are separated
by a sufficient distance to prevent mutual interference. These engineering factors
limit the maximum number of channels that can be used at each base station location.
The second option for increasing base station capacity is to cell split or
sectorize. Cell splitting is the division of a nondirectional site with a circular coverage
DENNY & ASSOCIATES, P.C.
CONSULTING ENGINEERS
WASHINGTON, DC
Engineering Statement Page 5
Albemarle County, Virginia
area into several pie-shaped sectors using directional antennas. This permits a more
efficient reuse of frequencies and allows tower locations to be separated by shorter
distances. However, cell splitting only has limited benefits and often requires that
many of the sites within the system be sectorized before these efficiencies can be
realized fully.
The last means of increasing cellular system capacity is to implement an
additional limited coverage site in the affected area thereby freeing up traffic at the
overloaded sites. In most cases, all three of these options are implemented to provide
the most reliable service and to meet customer demand.
PROPOSED HICKORY SITE
The proposed Hickory site is located on the west side of U.S. Route 29 at
geographic coordinates 37° 59' 36.5" North Latitude, 78° 35' 18.9" West Longitude.'
The transmitting antennas will be mounted on a 150-foot monopole supporting
structure to be erected at the site.
Construction of the Hickory facility is necessitated by the lack of reliable
coverage along U.S. Route 29. This is supported by the predicted coverage study of
Figure 1 which shows predicted coverage from the existing 360° Communications's sites
in the vicinity of the Hickory site. Further support is detailed in the depiction of
measurement data in Figure 2 which validates the coverage prediction and customer
complaints. Figure 3 depicts the predicted coverage for the 150-foot tower proposed for
construction at the Hickory site. Use of a lower tower height at the Hickory site will
have a detrimental impact on the ability of the site to improve coverage along U.S.
2 Geographic coordinates are referenced to the 1983 North American Datum (NAD83).
DENNY & ASSOCIATES, P.C.
CONSULTING ENGINEERS
WASHINGTON, DC
Engineering Statement Page 6
Albemarle County, Virginia
Route 29. This is depicted in the predicted coverage study of Figure 4 which estimates
the coverage for a tower height of 100 feet above ground level (AGL). Furthermore,
reducing the proposed tower height at the Hickory site will very likely necessitate the
need for additional towers along U.S. Route 29.
PROPOSED AVON SITE
The proposed Avon site is located to the west of State Route 20, at geographic
coordinates 37° 59' 52.3" North Latitude, 78° 29' 52.9" West Longitude.3 The
transmitting antennas will be mounted on a 80-foot monopole supporting structure to
be erected at the site.
Construction of the Avon site is necessitated by excessive cellular traffic
demands on the 360° Communications system. The coverage issues described relative
to the Hickory site are not germane to the proposed Avon service area. In contrast to
the Hickory site, most of the Avon service area already has adequate signal strength.
The problem in the vicinity of the Avon site is the very high likelihood that a new or
handed-off cal1 from another site will not go through due to the unavailability of a voice
channel to support the call. The Mobile Telephone Switching Office (MTSO), which
controls the creation, completion and switching of cellular traffic, has the capability of
monitoring the number of failed calls, commonly referred to as blocked calls. In the
area of the proposed Avon site, 360° Communications has recorded the number of
blocked calls to be as high as 20 percent above their maximum capacity.
360°Communications engineers their cellular system to have a blocked call percentage
lower than two percent.
3 Geographic coordinates are referenced to the 1983 North American Datum (NAD83).
DENNY & ASSOCIATES, P.C.
CONSULTING ENGINEERS
WASHINGTON, DC
Engineering Statement Page 7
Albemarle County, Virginia
360° Communications has made every effort to increase capacity without
adding sites. Of the options discussed earlier for increasing capacity,
360° Communications increased the number of channels at the Carters Mountain and
downtown Charlottesville sites to 38. This is 360° Communications theoretical
maximum before they begin to give and receive interference to other sites in their
system. Secondly, 360° Communications has planned to sectorize both the Carters
Mountain site and the downtown Charlottesville site. Since sectorized facilities are
typically closer together with smaller service areas, the proposed Avon site is also
instrumental in 360° Communications's plans for sectorizing the neighboring facilities.
This site at a tower height of 80 feet AGL is predicted to provide adequate coverage to
free up traffic at the overloaded downtown Charlottesville and Carters Mountain sites.
While it is true that closer placement of cellular towers generally permits
towers of reduced height, the height cannot be so low as to obstruct the antenna from
the area of service. Reducing the height reduces the service area and the effectiveness
of the new site to absorb traffic from the adjacent, overloaded sites and only
necessitating additional sites.
Figure 5 is a study showing the predicted coverage achieved from the Avon
site by employing the proposed tower height of 80 feet AGL. The study clearly shows
that the Avon site will be able to absorb cellular traffic from parts of U.S. Interstate
64 and State Route 20. Figure 6 shows the predicted coverage with the tower height
reduced below the tree line to 60 feet AGL. Clearly, reducing the height to 60 feet
negatively impacts the effectiveness along U.S. Interstate 64 and greatly limits the
ability of the site to absorb cellular traffic from those areas.
DENNY & ASSOCIATES, P.C.
CONSULTING ENGINEERS
WASHINGTON, DC
Engineering Statement Page 8
Albemarle County, Virginia
STATE OF THE ART
It is all too often asserted that new technologies will soon make cellular
telephones obsolete. Some of these technologies include Personal Communications
Services (PCS), Enhanced Specialized Mobile Radio (ESMR), and satellite telephones.
PCS and ESMR are similar to cellular in that they employ towers to provide service to
their licensed coverage area. Satellite based systems generally propose to use
numerous low earth orbit satellites (LEOS) to provide global coverage. All of the newly
proposed satellite systems will employ dual mode phones. This means that the phones
will first attempt to use a terrestrial based connection like cellular, PCS or ESMR
before connecting to the satellite. Satellite based systems are extremely ambitious
projects which have not been fully developed or deployed. The satellite based operation
of these systems adds increased cost to the purchase and operation of a satellite phone.
In contrast, cellular is an existing mature system which currently is serving the public
need and necessity at a reasonable cost.
The U.S. Congress recently recognized this public service by assuring that
one type of wireless service is not discriminated over another. Specifically, Section
332(c)(7)(B)(i)(I) of the recently passed Telecommunications Act of 1996 states that:
The regulation of the placement, construction, and
modification of personal wireless service facilities by any
State or local government or instrumentality thereof-- (I)
shall not unreasonably discriminate among providers of
functionally equivalent services; and (II) shall not prohibit
or have the effect of prohibiting the provision of personal
wireless services.
PCS facilities are being entirely built based on portable phones instead of
mobile. There is a clear consumer preference for portable phones over mobile phones
DENNY & ASSOCIATES, P.C.
CONSULTING ENGINEERS
WASHINGTON, DC
Engineering Statement Page 9
Albemarle County, Virginia
in all of the wireless services. Therefore, declaring that mobile phones are sufficient for
cellular systems would clearly impede cellular's ability to compete with new wireless
services.
CONCLUSIONS
360° Communications is proposing to improve the reliability and
availability of cellular service along U.S. Route 29, U.S. Interstate 64 and State
Route 20 in Albemarle County, Virginia. 360° Communications has used reasonable
engineering judgment to select the proposed Hickory and Avon site locations and has
proposed tower heights minimally necessary to achieve the stated objectives.
Alan R. Rosner, P.E.
Subscribed and sworn to before me this 7th day of May, 1996.
Donna Holzwart
Notary Public, District of Columbia
My commission expires November 14, 1998
Figure 1
`o \ \\\
\ \•\/d o I \ co o
c \`\\\ ` \\ \\
co
Z a y \ \ : ur
L _ a J lii QO , L ° al p.\ m8 1) 0.0 k ,W ` = \ m W Z d \ n a_ \W u
_ :0h
0 co 00 \ x \8. 0 \ �„ III-
% '
E 5 N w E \\ \ .-,D \
N\ % N \\N i \ \\
V\ \ \ \ \\ \ v,..
N.
N, N ,7 ‘, V\
: \ \\ : . \41C■•\-:;1%s 4 ss\NN,
... •\• ., `. ,
\ N...c .':'Nhi„. . ‘x, N, N.\
\N, N \ \
\
�\ \\ \ \\\\\\`• \\ ‘\\\\\�
\ \ \
• 1, \ \ \\\\ �\ �\•�\\ \
• \ \
Figure 2
i �
)i2
Q
}
IMO
\ -- Zu
Q
uQ � � U aW
? m o
Q W W J
O W a
f- H a
�- l_ I Et re . U j 2
Q Q uJ z } U
~
> /hi` Z UU aia 2 O
�� � O Q N O\ G7 cu
0.a � Qo a
CC ATIOC. � g o W m cu
igatort.... ,
co
M 1St arilltj) W °
IWN E
i Y
\''' ;' E..)
x cc
co
p o
a
----'1'-7 / co —
m o
0 c U
• tea°) Z
) aC y
N w co
C
Y ao co p
N a) y
I) N
1.
N N N
:J515 •15 E
—� O O O G)
• < :ti < if
1111
"L c cn
S
Z
H
°� C. 8
-- Q
W r
S / _
o 7O
Figure 3
Tit \ \\\
\,414..,* co
a C F' UL T
D • O C O \ L N C V)A J N \
'� p m it5 0E
U \ \ \m ,- a m a
n a
°'UO \ @o ° E E E
Um u m
\
At \ ,,,
\\... \\I•k\I 4N::\:7,':"\\:\ \\:\\\ ss\\41\41\s \
X\\ . S li.ji: \‘..
Nsd. \ \ \ .s.'\\:..\\\ - ‘41. \ \ \ \\\''
\\ \ •\\ ' ..' N 7' Net 4$ ' V
NS
ss,..,\:‘.:, \
\ 'N .
\\,,,,.. \` 'N
,N,„
.•,,,,,, , \\N :\\
...„.„..,,,,
\ \ -. - ',..:.•.:::::5.*::.,,,,,,s.
\\\\ \ ' ., .. \.}.:I::::11911.3.5...t.,%,-".„
-:::::::::::::::::. „
\z,.• .... „. „
\ .„..
. . . v ,N ....., ,.: N\\\ \ Nt.
sk, ,,, ,\ .•,,..‘• •,..... \*.. -7 . ..
\\N
' \4 k N k.,,N\ \
N \, .\ \\ \
....A,„:„. \,„,
, --------„,___ „ <„\\ \, N"
,4,:
......„ .
„.....A.... \ .. .... , \ , ,,,,,
•
Figure 4
d , • W
1 .. A k \\\ V ` V�\ 0)2 �.
t� Z c c
W aZ � f0 �\ ` ■ \ Na \v
�.
r. b O Z \ m 3 rn.4 :t 2 g \ \ a m c N cis
M J U a Z or \ � \ a'� \\\ a� H o
T to _ �- W Z W d \ 2 O ct, C \ _\ \ c \ — O N w
U M J Vl Uf Y _ ♦ \ E \ IC a9 _ N
i -'-- a 2
Q O _
W O 2 O \ O N O g V \ A la
a \ o 0 o m
R - \ U U m N \ N 00 L .E \ g ? g C
o o o Q Q \ _ o,rnm 2 A.: Q Q I\ \ o
\\\ \• \\` \\ \\\\ �,0 \ \\ "\\\\\\\\
V,,,,\.. \ \\ \ \ �;.- \ \\
, ,-, 34:\ ,,.
:\\ \\\ ;':...:1.: \'‘‘,.."s..'N.:::,s, \\ :\ N\\\\\\ \ \\\\\T:\\\\::\::\\\:\' ''
‘\ \ \
\ - \ \‘ \
\ \\\* \ \
.\ \\ \ \ \ ■
\ \ \ \ \
i \ \ \\
% \ ,
\ \ \ \ \ \` \ \
• Figure 5
....., .N., i. 7 \\,
FL-
2 E2
I d
\al CL I Q
h m \01 m \\\\ \ \\\ N —W C N N \
c \\ IL
° 'S 4'es D i= D \
CD 'to
N °\Z I1Ifl \, Q Y a� N o Z ` cr) 9 )�N E N N N •n_ W w a OC a, a) a) g r z � C . o0o \in _ J y � g Ni\ \— \ g � ° myt EEErn y _ 2 g § 1 \\ •— ya . \\ o ��\; ti N Q •
• III\ W \ D.. 8."5 '_ \ \\
\\ \N, \\ \\\ \ .'�.. \ \\
\ \.
\ N\ \N - '''\:, ,
V.,\
:;:N.. .,:t, ;. ‘,
•
\ . ..
. , -.., N \
, . .
\ -:.*, , . ,.
\ . N‘,..., 4N.
\ := ....:. 7 \„, , ,
\s .:-N\ N . '
N \ t',' . W ' \\ \ 1.\
\ \ \\\ \A
\
: \ \\ -
\
Figure 6
`o \ \\\ \ \� 7 \ \\ \\ \\
Q W t7) f) \\ \...e r, k \‘‘ :\\\•
cD To
\N p L w \ E CU \ . 0
T O . \` a co
i. z o g \ > o
cia J i OU U \ tOP Q Uh '*k
W d \ \\`J V)
0 Q 110
\ 15 .o.— E \
w W OL cc) `\\U v J m O Q M Q Q Q ll..
O O \ c0 Q otS \ E V) 3 C \v` \ \ —
E 3 \N Lk1 >, \ o_x 2 N\ \ :* \
' \N, \ k\ , N. N \ ..
\\N. \ ;,
\ \\\\\ \ N
N ',\: : ., "
_ , ."..,Nt
mot. , `. - �•
\. 'N \ * \ ,, N.-
.\ \\ \ \ w \,
\ \ \
\,
\. , , \ ,\ \
c„„„, ....„ „:„ N ,., , , s ;
\ \ , , v ,N „,\,
• z..,:\s„ ,:ss,,, -..\\N\ ,„ N . :. ... „
... \
. „„ -, N\-\\ ,
, • k \ ._.
\\\\
\\* -_,. ,... \s, ...,_ , .
\ \\ \\\ \ \ \\\
_ \ ‘, \