An Introduction to
Neutral Host Distributed Antenna Systems
99
Pine
Street
ƒ
Albany,
NY
12207
ƒ
(518)
434-2288
Table of Contents
Introduction
3
Overview of Distributed Antenna Systems (DAS)
4
Benefits of a Neutral Host DAS
6
Improved Coverage and Quality of Service:...................................................................6
Increased Capacity:.........................................................................................................7
Capital Cost Reduction: ..................................................................................................7
Speed to Market for Service Providers: .........................................................................7
Evaluating Neutral Host Opportunities
8
Site Survey
10
System Design
11
Construction
12
Optimization and Verification
13
Summary
14
Introduction
The demand for seamless voice and data coverage is driving wireless infrastructure.
The licensed carriers built their networks to standards that provide voice mobility. With
the deployment of wide area high speed data technology – CDMA2000, 1xEV-DO and
EDGE, the carriers have responded to next generation demands for wireless data
communication. Users of wireless services expect them to work where they are. It is a
challenge for carriers to provide seamless voice and data coverage indoors. The
incumbent wireless infrastructure was not designed to provide in-building service. The
concrete and steel materials in our cities and office complexes are barriers to macro
network RF signal.
The integration of optical technology in RF distributed antenna systems (DAS) provides
an efficient indoor coverage system for the licensed 800 and 1900 frequency bands,
WLAN, WiFi and 800 MHz public safety bandwidths. For an in-building network a single
distribution backbone with a multi-band distributed antenna system can accommodate
CDMA, TDMA, GSM, iDEN, LMR, DCS, GPRS and WiFi 802.11x, all in an interference-free
environment.
An in-building wireless network typically is a series of hubs, repeaters, and multipleband antennae placed within the building to accommodate and extend signals from the
wireless carriers. Infrastructure includes a Distributed Antennae System (DAS), an
equipment room, cabling and a network operations system, in either an active or
passive DAS solution. Active systems use power to transport the RF signal, passive
systems do not use power to amplify or convert the RF signal and require only cabling
and antennae to operate. Facility size, design, architecture, locations and number of
inhabitants determine the network design. Different buildings require different
solutions, as such no one vendor or OEM hardware provides a fits-all solution.
Overview of Distributed Antenna Systems (DAS)
To overcome the coverage and capacity problems inherent in the unique features of
subways, parking garages and other in-building environments that make it difficult to
provide quality service for mobile users, special antenna systems are deployed and
distributed in-building. A typical DAS system, multiple antennas or transmitting
elements that cover smaller zones (up to 20,000 square feet) are strategically
distributed throughout the facility and connected back to the low power equipment via
longer cables and system interconnections. In contrast, a typical macro wireless
network antennas are connected to high power transmitting and receiving equipment
via shorter cables arranged to cover large geographical areas (miles) from one antenna
location. Macro antenna systems tend to be bigger and higher, while the DAS systems
have many smaller antennas located very close to the mobile users.
DAS systems can be broken down into two main categories; Active or Passive. Active
systems use power to transport RF between the service provider’s equipment and all
parts of the DAS. These systems are generally used within large enclosures having
complex wall systems.
Figure 1: Active System Diagram
Passive systems do not use power to amplify or convert the RF signal and require only
cabling, connectors and antennas to operate. Many of the smaller less complex
locations can be served with passive systems. The size of the venue, complexity, and
other factors will determine the type of system required during the design phase of the
process.
Figure 2: Passive System Diagram
Benefits of a Neutral Host DAS
Distributed Antenna Systems that are designed and available for use by multiple service
providers are commonly referred to as neutral host systems. If a DAS system is
designed and deployed properly, common coverage and capacity benefits to more than
one provider via a single distribution backbone can be achieved without a need to add a
series of independent systems. Each carrier needs to provide only the head end
equipment, via a dedicated base station or a donor antenna/amplifier, to connect their
macro network to the DAS system. A donor site is one that is not exclusively used for
the DAS system but also provides service to areas outside of the DAS.
Neutral Host Distributed Antenna Systems are a reliable and innovative solution to poor
coverage inside buildings, large venues requiring capacity, and inconsistent RF
environments where it is difficult to improve quality. There are numerous benefits
associated with these systems not only for the service providers and the consumers, but
also for property owners.
Improved Coverage and Quality of Service:
Wireless devices often encounter difficulties maintaining a reliable connection inside
buildings. Subscribers expect and demand wireless access wherever they are, whether
it’s on the 75th floor of a Class A office building, or in its underground retail concourse,
at a shopping mall, casino, convention center, airport, or even on a college campus.
Large buildings made of metal and concrete such as malls, or underground
environments like subways and parking garages form RF resistant structures where the
penetration losses are too great to maintain a reliable link to the outside macro cell
sites. This is true even in mature wireless networks that have a high density of macro
sites covering the outside environment. Distributed Antenna Systems eliminate poor
wireless reception in these types of environments.
As with any in-building solution, the primary benefit of a Neutral Host DAS is improved
coverage throughout the interior of a building or venue. In general, installation of a DAS
will result in increased coverage, improved call clarity and higher data throughput. The
wireless service providers benefit by accomplishing two key revenue objectives;
increased customer satisfaction / decreased churn, and increased in-building airtime
minutes-of-use. Additionally, the end user will experience fewer blocked, dropped and
missed calls. The property owner benefits by having their customers connected longer,
resulting in more time spent within the property, and increased tenant and visitor
satisfaction.
Increased Capacity:
Wireless carriers often have to off-load traffic from large venues during special events or
at peak-usage times by installing dedicated base stations, costly and complex cell
splitting or re-sectoring the original macro network. All of these procedures lead to
increased capital expenditures and in many cases degraded performance in the
surrounding macro network. Using a Neutral Host DAS system to provide capacity for
large venues allows macro cells to address other network related issues and allows for
reduced power levels, reducing interference and increasing bandwidth.
Installation of a Neutral Host DAS provides the opportunity for the wireless service
providers to off-load call volume from the existing macro-cell network. The DAS replaces
the need for additional base stations or tower locations that may only end up being
partially utilized to solve the capacity problem, while the other sectors could be
redundant wasted capital. In addition, off-loading subscribers from the macro network
to the self contained DAS eliminates any re-sectoring or cell splitting of the surrounding
macro cells. The net benefit of a DAS system is a less expensive solution with
equipment that is more efficiently utilized, is less intrusive and does not disrupt to the
surrounding macro network.
Capital Cost Reduction:
Equipment, labor, and maintenance costs for deploying in-building systems can be
expensive and wireless providers find it difficult to justify the ROI for such systems
except for the very top tier venues. By utilizing a neutral host model multiple carriers
share the cost associated with these installations while improving subscriber
satisfaction and ultimately increasing minutes of use on their system. Since the cost
associated with providing service to in-building and other underground or RF resistant
environments is shared among multiple carriers in a Neutral Host DAS model, the
medium and smaller venues are becoming economically feasible.
Speed to Market for Service Providers:
Faced with an ever-consolidating market, wireless number portability mandates, and
customer churn, carriers need to quickly expand and improve network coverage based
on subscriber demand. Well designed Neutral Host DAS networks are an efficient
resource for wireless service providers attempting to satisfy the needs of their
customers and investors. Continued funding of the current standard solution
encompasses incremental costs and time-to-market.
Evaluating Neutral Host Opportunities
Proper evaluation of capacity, signal strength and signal quality for each of the mobile
service providers is required to assess the need for a neutral host system.
Capacity is evaluated both within the venue of interest as well as in the surrounding
macro network. A venue may have adequate signal strength but if the venue hosts a
significant number of subscribers, the sites that serve the area may be over utilized. In
this scenario a neutral host system may be driven by either a dedicated base station or
a repeater that is fed from a less utilized site.
Signal quality is an important factor in determining the need for a neutral host system
and must be considered for multiple carriers. Signal quality can be measured by using
equipment that utilizes sophisticated algorithms to generate Mean Opinion Scores
(MOS). Alternative technology specific indicators are also used, such as Bit Error Rate
(BER) for GSM networks, Frame Error Rate (FER) for CDMA Networks and Signal Quality
Estimate (SQE) for iDEN networks.
Adequate signal strength should not be equated to good signal quality. While signal
strength is certainly a factor in determining signal quality it is not uncommon for good
signal strength to be present within a building while the signal quality is poor.
Interference in one form or another is generally the cause of poor quality occurring in an
environment of good signal strength. An example of this is shown in figures 3 and 4
below. Note that in these figures the received signal strength (RSSI) is adequate at the
outer edges of the building, but the signal quality (using FER as an indicator) is marginal
to poor.
Carrier 1 RSSI
# -85 to 0 dBm
# -90 to -85 dBm
# -95 to -90 dBm
Less Than -95 dBm
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1 52 0
CA CU
CA CU
CA CU
V1 0 7
VE S T I BU L E
A2 - 1
A 2- 2
A2 - 3
A 2- 4
V1 0 7
1520
W A T ER R OOM
S TA ND-B Y
A 3- 1
A3 - 2
A3 - 3
A4 - 1
A3 - 4
A3 - 5
A3 - 6
A4 - 2
15 20
S W I T CH GE A R
GRE E NSI DE
1505
CON F E RE NCE
15 05
316
OF1 F
I CE
1320
13 20
13 16
1 50 6
FI R E P UM P
ROOM
1506
15 06
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13 15
1315
A3 - 7
A2 - 5
A 2- 6
A2 - 7
A 2- 8
A3 - 8
A3 - 9
A4 - 3
A 3 - 12
A4 - 4
1510
1504
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14 10
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SA N D T R A P
1 32 3
1 32 2
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13 23
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13 22
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1 4 10 A
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A2 - 9
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15 10
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1330
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PT R / F AX
P T R / FA X
ST ORA GE
14 1 0 B
1 5 04
L IB RA RY
A3 - 1 4
A 3 - 15
A4 - 5
B3 - 3
B4 - 1
13 13
13 30
B 1- 2
15 04
OF1 F
I CE
313
OP E N OF F I CE
B1 - 1
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E M E R.
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B 3- 4
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CHI L L ER P UM P ROOM
B3 - 6
B3 - 8
B3 - 9
TRA M M E L L C ROW COM P ANY
B4 - 2
CA CU
B3 - 5
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1327
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13 27
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1 5 0 2 1502
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B 3- 7
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1 3 27
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S T ORAGE
13 10
CON F. RM
1 41 1
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1310
13 26
13 25
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1 41 4
14 12
15 01
14 14
I DF
14 11
V1 0 5
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C1 0 4
C1 0 2
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10 0 1 A
P T R / F AX
D1 - 3
D9 - 1
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D1 - 1
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D2 - 1
D2 - 2
12 3 0
D3 - 1
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D3 - 3
D4 - 1
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VE S T I B U L E
PT R / F A X
P TR /F A X
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1 0 02 A
DE M O L A B
D2- 3
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1 00 1
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L ET
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10 02
12 22
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D2- 5
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D3 - 1 0
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BL I ZZ A R D
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NUB BL E L I GHT
CON F11.2 0RM .
1001
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D6 - 7
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D7 - 1 3
D7 - 1 4
D7 - 1 5
D8 - 1 3
D8 - 1 4
D8- 1 5
11 20
12 20
D4 - 9
L OB B Y
P T R / F AX
OP E N OF FI CE
10 01
12 30
OP E N OF FI CE
V 10 1
11 30
VE S TVI10B1 U L E
V1 0 1
0
50
feet
Figure 3: Carrier 1 RSSI
100
Data collection software is used to produce coverage plots as shown in Figures 1 and 2
for each provider. This data can then be used to assess the suitability of the building
for neutral hosting as well as to identify the areas of the building that require coverage
enhancement.
Carrier 1 Fram e Error Rate
# 0 to 2
# 2 to 3
# 3 to 5
Greater Than 5
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CACU
CACU
1520
CACU
V1 0 7
VES T IBU L E
A2 - 1
V1 0 7
A2 - 2
1520
W A T ER R OOM
ST A ND-B Y
A3 - 1
A3 - 3
A3 - 2
A4 - 1
15 20
SW IT CH GEAR
GRE ENSI DE
1 155 005 5
CON F ERE NCE
OF1F3 1 6ICE
1320
13 20
13 16
A2 - 3
A2 - 4
A2 - 5
A2 - 6
A2 - 7
A2 - 8
A3 - 4
A3 - 5
A3 - 6
A4 - 2
A3 - 8
A3 - 9
A4 - 3
1506
F IR E PUM P
ROOM
1506
15 06
OF F ICE
13 15
1315
A3 - 7
1510
1504
BEN CH L AB
14 10
A3 - 1 0
OF1 3F1 4ICE
SAN D T R AP
1323
1322
CON F . RM .
1321
OF F ICE
13 23
OF F ICE
13 22
A3 - 1 1
A3 - 1 2
1410A
13 14
A4 - 4
13 21
REC EIVIN G
A2 - 9
A2 - 1 0
PT R /F AX
A3 - 1 3
1330
PT R /F AX
PT R /F AX
PT R /F AX
15 10
ST ORAGE
1410B
1504
L IB RARY
A3 - 1 4
A3 - 1 5
13 13
13 30
B1 - 2
15 04
OF1F3 1 3ICE
A4 - 5
OPE N OF F ICE
B1 - 1
A3 - 1 6
PT R /F AX
B1 - 3
1510
1503
PL OT T ER ARE A
1507
HAZ ARD
2
CON F1.3 1RM
.
B1 - 4
B1 - 6
B2 - 3
13 12
B1 - 5
B2 - 1
B3 - 1
B3 - 2
B3 - 3
EM ER.
1503
T EL EPHONE
B2 - 2
B5 - 1
B4 - 1
07
EL E1 5CT
RI C
15 0 3
1502
B5 - 2
15 07
B5 - 3
BAD GING
B3 - 4
1 31 1
311
1
1501
CHI L L ER PUM P ROOM
B3 - 6
B3 - 9
T RA M M E L L C ROW COM P ANY
B4 - 2
CACU
B3 - 5
B3 - 8
B5 - 4
1327
1303
BUI L DING SER VICES
13 27
1326
OF F ICE
15 02
1303A
1411
1412
1414
1502
1416
13 03
IDF
1 3 2 5OT
DIV
BL D G. EL ECT R IC
SEC URIT Y & S AF ET Y
B3 - 7
1501
B4 - 3
B5 - 5
1327
B5 - 6
ST ORAGE
13 10
CON F . RM
1411
L DF
1412
ST ORAGE
1310
13 26
13 25
1416
1414
14 12
14 14
15 01
IDF
14 11
V1 0 5
14 16
V1 0 3
VES T IBU L E
VES T IBU L E
V1 0 4
V1 0 6
C1 0 6
COR RIDOR
V1 0V130 3
V1 0 4
EM ER. E L EC.
VES T IBU L E
#
VES T IBU L E
C1 0 6
V1 0 6
C1 0 6
V1 0 5
V1 0 6
13 04
V1 0 5
V1 0 4
1212
1210A
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1304
1304
13 05
1302
1301
1401
1402
1403
1404
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1109
J AN .
13 02
1403
14 01
COP Y/M A IL
ST A GING
13 05
1 3 0 8 ROOM
CON F ERE NCE
12 11
S T ORAGE
1401
13 0 5
OF F ICE
12 12
CON F . RM .
C1 0 1
M E N' S L AV
1211
OF F ICE
1213
EAS T ERN POIN T
14 03
M E N' S L AV
14 04
1402A
13 01
M OT HER S ROO M
1404
1109
11 09
13 08
EL E V.
M E CH.
1402
C101
COR RIDOR
C105
COR RIDOR
1110
1111
OF F ICE
OF F ICE
11 10
11 11
1415
C1 0 3
1 40 4A
1202
CON F .RM .
1108
BDF
EL E CT RI CAL
14 15
11 08
W OM EN' S L AV
11 03
1103A
C9 - 1
C9 - 2
C9 - 3
C9 - 4
C9 - 5
C9 - 6
D9 - 1
D9 - 2
D9 - 3
D9 - 4
D9 - 5
D9 - 6
1103
QUI ET
1205A
C1 0 4
C1 - 4
1105
120 5A
C1 0 2
1202
C1 - 5
1209
12 08
1207
1206
12 04
OF F ICE
OF F ICE
OF F ICE
OF F ICE
12 09
12 0 8
12 07
12 06
1203
OF F ICE
C1 - 6
QUI ET
1205B
1101
OF F ICE
12 0 4
BRE AKROOM
12 02
12 03
120 5B
1102
OF F ICE
OF F ICE
11 01
11 02
1103A
1104
SHOW ER
110 3A
1106
1107
OF F ICE
OF F ICE
OF F ICE
OF F ICE
11 04
11 05
11 06
11 07
COR RIDOR
COR RIDOR
C1 0 2
C1 0 2
C1 0 4
C1 0 4
V1 0 2
1001A
PT R /F AX
D1 - 3
D4 - 2
D1 - 1
D1 - 2
D2 - 1
D2 - 2
1230
D3 - 1
D3 - 2
D3 - 3
D4 - 1
D3 - 4
D3 - 5
D3 - 6
D4 - 3
D6 - 1
D6 - 2
D7 - 1
D7 - 2
D7 - 3
D8 - 1
D6 - 3
D6 - 4
D7 - 4
D7 - 5
D7 - 6
D8 - 4
D8 - 2
D8 - 5
D8 - 3
D8 - 6
D6 - 5
D6 - 6
D7 - 7
D7 - 8
D7 - 9
D8 - 7
D8 - 8
D8 - 9
D6 - 7
D6 - 8
D7 - 1 0
D7 - 1 1
D7 - 1 2
D8 - 1 0
D8 - 1 1
D8 - 1 2
D6 - 9
D6 - 1 0
D7 - 1 3
D7 - 1 4
D7 - 1 5
D8 - 1 3
D8 - 1 4
D8 - 1 5
VES T IBU L E
PT R /F AX
PT R /F AX
1201
V1 0 2
1130
CAP E NE DDICK
V1 0 2
CON F . RM .
D4 - 4
1002A
DEM O L A B
D2 - 3
1222
1221
D2 - 4
12 01
1002
12 21
BL A CK IC E
1001
1002
T OI
L ET
CON F . RM .
10 02
12 22
D4 - 6
D2 - 5
D2 - 6
D3 - 7
D3 - 8
D2 - 7
D2 - 8
D3 - 1 0
D3 - 1 1
D3 - 9
D4 - 5
D3 - 1 2
D4 - 7
BL I Z Z AR D
D4 - 8
NUB BL E L IGHT
CON F1 1.2 0RM .
1001
220
CON F1.RM
.
11 20
12 20
D4 - 9
L OB BY
PT R /F AX
OPE N OF F ICE
10 01
1 2 30
OPE N OF F ICE
V1 0 1
11 30
01
VES TV1IBU
LE
V1 0 1
0
1115
BIR D ISL AND
1108
1103
1404A
SHO W ER
C1 0 1
2
1 3 06
1103B
1404A
14 02
13 06
W OM EN' S L AV
C103
1
1305A
13 06
C1 0 5
EL EV.
1307
13 07
NO .
ST ORAGE
12 10
C1 - 3
EL EV.
1302
1309
1307
C1 - 2
NO .
09
ST1 3OR.
13 09
1210
EL E CT
CAL
1 2 1RI
0
C1 - 1
COR RIDOR
1301
12 13
50
feet
Figure 4: Carrier 1 Frame Error Rate
100
11 15
Site Survey
A site survey is performed prior to the final design. The objective of the survey is to
characterize signal propagation within the building, investigate donor signal options and
to investigate equipment space and cable routing issues. Proper engineering and
planning will minimize capital expenditures while ensuring that coverage goals for each
of the mobile service providers are met. Several factors must be considered when
designing a neutral hosts system. Assuming the target coverage area has been
identified as described above, the first of these is to characterize signal propagation
within the target area. To characterize the building test transmitters are located at
various locations within the building. A receiver and mapping software is used to record
the signal strength at various locations within the building. A sample transmitter test is
shown in Figure 5 below.
##
CON F .RM .
23 20
# # #
#
#
#
23 1 0
CAC U
##
A2 - 1
#
A2 - 2
232 0
A3 - 2
A3 - 3
#
#
A1 - 1
A3 - 4
A3 - 5
A3 - 6
Trans mitter Tes t Path Loss
#
#
A2 - 8
#
B1- 3
#
#
231 9
234 0
B1 - 5
B1- 6
B1 - 8
B3 - 3
B3 - 4
B3 - 5
B3 - 6
2410B
231 3
230 9
#
#
240 5
#
#
##
# #
#
C1- 3
241 2
#
∃
230 7
#
3 0S3L A V
M E2 N'
C2 0 5
230 2
D1 - 2
D1- 3
#
230 4
#
#
240 2
#
6
M E N'2S4 L0 AV
#
#
C2 0 3
240 9
#
#
# # #
2409
2302
240 9
2115
242 1
211 1
2402
C2 0 3
2407
W OM EN' S L AV
240 7
220 2
EL E CT RI CAL
ST O R.
#
2110
240 8
C203
C2 0 1
#
#
240 8
2 40 7
C201
COR RIDOR
W OM EN' S L AV
#
ST ORAGE
OF F ICE
C2 0 2
240 7A
211 0
2305
230 5
#
2421
2111
#
ST ORAGE
2406
ST A GING
240 2
2301
#
211 0A
240 6
210 1A
230 1
COR RIDOR
#
#
2401
2 40 1
230 5A
230 5
211 0
24 0 8
C9- 1
C9 - 2
C9 - 3
#
#
C2 0 2
2 209
2208
OF F ICE
OF F ICE
22 0 9
220 8
220 7
#
#
#
220 6
#
D3 - 1
D3 - 2
D3 - 3
OF F ICE
220 3
22 0 4
BRE AKROOM
DE E R ISL AND
CON F .RM .
#
211 5
#
#
#
D4 - 1
D4 - 2
CUT T YHU NK L IGHT
CON
2 2 0 1F .RM .
D4 - 3
#
D4 - 4
#
#
#
#
#
#
220 0
D2 - 6
D3 - 7
D3 - 8
223 0
D2 - 7
D2 - 8
D3 - 1 0
D4 - 5
D3 - 1 1
D3 - 1 2
2107
OF F ICE
OF F ICE
210 6
210 7
2108
#
2 109
OF F ICE
OF F ICE
210 8
210 9
C9 - 4
#
C9 - 6
#
2 1 02 150 5BB
# #
2 20 1
D2 - 5
2106
QUI E T
C9 - 5
#
#
#
D3 - 6
QUI E
2 1T
05A
210 4
21 0 3
220 5B
D2 - 2
D3 - 5
2104
OF F ICE
210 5A
OF F ICE
2 211 001 1
22 05B
D2 - 1
D3 - 4
03
OF F2 1ICE
2202
220 2
210 2
PT R /F AX
D2 - 3
2102
OF F ICE
OF F ICE
2203
QUI ET
##
#
C2 0 5
22 04
220 5A
OF F ICE
COR RIDOR
QUI ET
22 05A
2206
OF F ICE
D3 - 9
#
#
2304
C2 0 6
D2 - 4
222 1
ST
2 4OR.
01
#
M A IL /COPY
ST O RAGE
2 30 2
22 21
OF F ICE
222 2
C2 0 1
230 3
230 4
2222
OF F ICE
230 1
C2 0 7
#
C2 0 5
#
#
#
##
#
C206
2306
COR RIDOR
230 6
S T OR.
2210
221 0
DUM P L IN G ROCK
NOR T H E ND
2 411
241 1
COR RIDOR
1
D1 - 1
#
2
221 0
EL E CT RI CAL
2207
C1 - 1 2
#
2303
C1- 9
C1 - 1 1
#
2307
C1- 6
C1 - 1 0
#
S T ORAGE
2412
C2 0 7
230 7
#
2223
IDF
241 2
240 3
C2 0 7
###
#
#
#
#
Transmitter Location
#
230 6
222 3
CAC U
240 4
NOC ST ORAGE
2403
NO .
C1 - 5
C1 - 8
CON F . RM .
2410A
2404
23 1 2
ST ORA GE
#
##
S T ORAGE RM .
240 3
2312
CON F .RM
.
CAC U
#
C1 - 7
#
DAT A CE NT ER
NOC
23 0 9
SNOW B A NK
J AN .
#
2405
2309
2318
231 8
221 0A
#
240 4
24 0 5A
#
#
ST ORAGE
#
C1 - 4
240 5
EL EV.
C1 - 2
#
#
2410
24 1 0
CAC U
PDU
B1- 9
2330
C1 - 1
B3 - 2
CAC U
NO .
#
B3 - 1
231 0
2313
OF F ICE
231 9
#
2319
B1 - 7
BEN CH L AB
#
#
DAT A CE NT ER
231 4
EL EV.
B1 - 4
#
OF F ICE
#
A3 - 1 1
FM 200
231 8
IDF
#
2 310
A3 - 1 0
OPE N OF F ICE
B1 - 2
2410D
all others
2314
#
A2 - 1 0
#
23 3 0
B1 - 1
#
A3 - 1 2
#
2340
A1 - 6
A2 - 9
#
2 31 5
A3 - 8
P T R /F AX
A1 - 5
2315
A3 - 9
A3 - 7
OPE N OF F ICE
# -85 to 0
# -90 to -85
# -95 to -90
2 31 6
OF F ICE
A2 - 7
A1 - 4
2316
OF F ICE
#
A1 - 2
#
#
#
A2 - 6
A1 - 3
#
CAC U
2 31 7
CAC U
#
CAC U
OF F ICE
A3 - 1
A2 - 3
A2 - 5
#
CAC U
2410C
#
A2 - 4
##
PDU
2317
#
NOR ' EAS T E R
D4 - 7
2220
CON F .RM .
#
#
#
V2 0 1
#
# #
#
#
#
#
COR RIDOR
#
C2 0 2
#
#
#
220 0A
#
#
D9- 1
#
D9 - 2
##
D9 - 3
D8 - 1
V ES T IBU L E
#
D6 - 1
D6 - 2
D7 - 1
D6 - 4
D7 - 4
D7 - 2
#
D8 - 2
D7 - 3
#
PT RD8/F
AX
- 3
D9 - 4
D9 - 5
D9 - 6
2130
V2 0 1
V2 0 1
D7 - 6
D8 - 4
D7 - 5
D6 - 3
D8 - 5
D8 - 6
#
D6 - 5
D6 - 6
D7 - 7
D7 - 8
D7 - 9
D8 - 7
#
D8 - 9
#
D6 - 7
D6 - 8
D7 - 1 0
D7 - 1 1
D7 - 1 2
#
#
D8 - 8
D4 - 6
D4 - 8
#
D8 - 1 0
#
#
#
#
#
#
#
D8- 11
D8 - 1 2
#
BIG DIG
2120
CON F .RM .
212 0
222 0
D4 - 9
##
#
#
#
#
OPE N OF F ICE
223 0
#
#
##
PT R /F A X
#
#
#
50
D6 - 1 0
D6 - 1 3
D7 - 1 4
D7 - 1 5
D8 - 1 3
D8- 14
#
D8 - 1 5
#
0
D6 - 9
#
#
#
#
OPE N OF F ICE
#
21 3 0
#
#
#
#
##
100
feet
Figure 5: Transmitter/Building Characterization Test
Various transmitter tests are performed so that a thorough understanding of the
building’s propagation characteristics is obtained. As can be seen from the transmitter
test in figure 3 signal loss does not degrade in direct proportion to the distance from the
transmitter but is largely dependant on the building structure. Using the proper tools
and procedures to characterize signal loss helps to insure that the system is not over
designed but meets customer requirements.
Suitable equipment room space and it’s proximity to the coverage objective can affect
the type of system installed and overall cost of the system. These issues are
investigated at the time of the site survey.
Potential donor signals are also investigated for neutral host opportunities that may not
require dedicated base stations. These measurements are generally performed at the
roof level. A receiver capable of measuring multiple technologies and frequencies is
required for these measurements. Alternatively phones from various carriers with an
accessible diagnostic or debug mode can be used. Potential donor antenna locations
and roof penetration issues also need to be investigated at this stage.
System Design
The building characterization along with available equipment space determined during
the site survey is the basis for system design. The propagation model is optimized for
accuracy using the transmitter tests performed in the site survey. Each wall type within
a building affects signal propagation differently therefore each wall type must be
identified in the propagation model and assigned attenuation values obtained from the
information in the transmitter tests. This allows for optimum transmitter location and
minimizes required capital. The system design determines which OEM hardware
solution is appropriate for the venue. A partial design (one floor of a multi story building)
is shown in figure 6 below.
Figure 6: System Design
Construction
Once the proposed design is approved for installation by the building manager, a preconstruction site visit is completed. During this visit, equipment locations and cable
routes are verified, as well as acceptable contractors to perform any electrical or roofing
work that may be required. If any of the locations proposed in the design are not
acceptable to the building manager, the design is modified to allow for these changes.
Once final approval is obtained, the actual installation of equipment begins.
Construction begins with the installation of cabling, typically both fiberoptic and coaxial.
Cabling is routed from the main equipment room throughout the building to all the
antenna locations. A DAS system allows for the reuse of many network elements such
that trunking and hubbing minimize the amount of new cable required. Cable is run in
existing cable trays or utility chases where available.
The equipment deployment is fairly straight forward. The main equipment room typically
needs dedicated electrical services to handle both the DAS equipment and the carrier
equipment. The remote units and the antenna use minimal power and usually only
involve a 10v outlet.
Optimization and Verification
Upon completion of the construction phase, the system is tested and optimized. Each
coax and fiber optic cable is swept, isolation tests are performed, sources of
interference are investigated, donor signal levels are verified, and a final coverage
assessment is performed. The results of the coverage analysis reflect both coverage
provided by the external macro cell and enhanced coverage provided by the DAS.
Figures 7 and 8 below show sample plots that can be used to measure the success of
the installation.
Figure 7: Carrier 1 RSSI - Post Activation
Figure 8: Carrier 1 Frame Error Rate - Post Activation
The results of the post activation survey can be used to evaluate the success of the
installation and used as a baseline to help troubleshoot problems if they arise in the
future.
Summary
A well designed Distributed Antenna Systems (DAS) can provide a cost efficient
interference-free environment for indoor CDMA, TDMA, GSM, iDEN, LMR, DCS, GPRS
and WiFi 802.11x networks. Using a combination of high-tech test equipment, custom
software applications, and engineering procedures, a design-driven neutral host DAS
network can be implemented that minimizes capitol investment, controls operating
expenses, and meets the network coverage objectives.