Avitec FD 3100A, FD 3500A Users Manual
Operating Manual
FiberDAS Distributed Antenna System
FiberDAS Manual, Rev. E14
ii
Table of Contents
1 LINK DESCRIPTION .................................................................................................................................. 1-1
1.1 C
1.2 G
AUTIONS AND WARNINGS
ENERAL DESCRIPTION
............................................................................................................................ 1-2
...................................................................................................................... 1-1
1.2.1 Basic Principles ............................................................................................................................... 1-2
1.2.2 Functional Description.................................................................................................................... 1-3
1.3 S
PECIFICATIONS
....................................................................................................................................... 1-7
2 INSTALLATION........................................................................................................................................... 2-1
2.1 G
2.2 I
ENERAL PROCEDURE
NSTALL FIBEROPTIC CABLES
.............................................................................................................................. 2-1
................................................................................................................... 2-5
2.2.1 Minimizing Optical Reflections ....................................................................................................... 2-5
2.2.2 Cleaning Optical Connectors .......................................................................................................... 2-6
2.3 S
2.4 H
YSTEM ALARMS
UB SHELF AND REMOTE POWER SUPPLY BATTERY CHARGE MONITORING AND REPLACEMENT
...................................................................................................................................... 2-7
........... 2-7
2.4.1 Replacing the Hub Shelf Battery...................................................................................................... 2-8
2.4.2 Replacing the Remote Power Supply Battery .................................................................................. 2-8
2.5 I
NSTALLATION CHECKLIST
....................................................................................................................... 2-9
2.5.1 Inspect Received Items..................................................................................................................... 2-9
2.5.2
2.6 I
Recommended Tools ........................................................................................................................ 2-9
NSTALLING THE HUB SHELF
.................................................................................................................... 2-9
2.6.1 Rack Installation.............................................................................................................................. 2-9
2.6.2 Connect Fiberoptic Cables ............................................................................................................ 2-10
2.6.3 Indentifying Remote Locations ...................................................................................................... 2-10
2.6.4 Serial Bus, Telephone and Local Alarm Connections ................................................................... 2-10
2.6.5 Mains Power and Fuses................................................................................................................. 2-10
2.6.6 RF Connections ............................................................................................................................. 2-11
2.7 I
NSTALLING THE REMOTE TRANSCEIVERS
.............................................................................................. 2-11
3 MONITORING AND TROUBLESHOOTING.......................................................................................... 3-1
3.1 F
3.2 T
3.3 R
IELD SUPPORT NUMBERS
ROUBLESHOOTING TIPS
EGULATORY
........................................................................................................................................... 3-4
........................................................................................................................ 3-1
.......................................................................................................................... 3-2
iii
iv
1 Link Description
1.1 Cautions and Warnings
Throughout this manual, these terms appear which highlight the care that should be exercised to ensure
personal safety and proper operation of the equipment.
WARNING: Warning statements identify conditions or practices that could result in injury
or loss of life.
CAUTION: Caution statements identify conditions or practices that could
result in damage to this product or other property.
CAUTION: any modifications to this device not expressly authorized by
Remec, Inc. could void the user’s authority to operate this device.
CLASS 1 LASER PRODUCT
FDA/CDRH Class 1 laser product. All versions of the FiberDAS are Class 1 lasers products per
CDRH, 21 CFR 1040 Laser Safety requirements. All versions are Class 1 laser products per EN
60825-1:1994.
NOTICE
UNTERMINATED OPTICAL RECEPTACLES MAY EMIT LASER RADIATION. DO NOT
VIEW WITH OPTICAL INSTRUMENTS.
1-1
1.2 General Description
The FiberDAS Fiberoptic Distributed Antenna System provides extended coverage of wireless networks
throughout buildings and campus environments. The Hub Shelf is a 3U (5.25 inch) high, 19-inch wide
rack-mounted chassis. The Hub Shelf holds up to 8 Hub Transceiver Plug-Ins. The Hub Shelf is located in
a communications equipment room in the building and is connected to the wireless base station or repeater
via hardline connection. The Hub Shelf may also be connected to the radios of a wireless PBX. Each Hub
Shelf is configured with up to eight Hub Transceiver plug-in cards. Each card is connected to up to two
Remote Transceivers via two pairs of singlemode fiberoptic lines. The Remote Transceiver Units are
distributed throughout the building as necessary to provide coverage. The Remote Transceivers are
mounted, generally, above the suspended ceiling but may be mounted near the ceiling inside the room if
need be. The aesthetic and low-profile design of the Remote Transceiver makes it relatively unobtrusive.
The plastic cover may even be removed and/or painted to match the décor. Each Remote Transceiver is
connected to Hub Shelf via two singlemode optical fibers. Each Remote Transceiver has one RF port
which is connected to a user-supplied indoor coverage antenna. This port may also be routed through an Nway RF splitter to provide coverage from a number N antennas for the one Remote Transceiver. The
choice depends on the results of the engineering design for that particular structure as to the most costeffective way to provide uniform coverage. The Remote Transceiver is DC-powered, usually by the Remec
Central DC Power Supply. This is distributed from the power supply at the Hub location using the
conductor pairs in a composite fiber/conductor cable or by a separate two-wire cable pulled along with the
fiberoptic cable. The DC connector utilized at the Remote Transceiver can accommodate up to 14 AWG
wire.
The FiberDAS design is very versatile but certain options are available that target specific signal types and
applications. In addition to the single band versions from iDEN through UMTS, there are dual band
versions such as 800 MHz/1900 MHz and GSM900/GSM1800.
FiberDAS installation and setup is very simple. First, standard telcom grade singlemode fiberoptic cable
that is most suitable for the site is installed. The cable installer can terminate the cable on site easily with
the SC/UPC optical connectors. The Plug-Ins and Remote Transceivers of a given type are completely
interchangeable. The SC/UPC plugs directly into the Remote Transceiver at one end. The other end plugs
into an optical patch panel or directly into the Hub Shelf via an SC/UPC-to-SC/UPC adapter. If the patch
panel is used, SC/UPC-to-SC/UPC jumpers must be used to connect the Hub Shelf to the patch panel.
Built-in optical loss compensation automatically equalizes the gain in both the transmit and receive paths
so the transmit RF power is known for a given input RF power and the receive path sensitivity is
optimized. The only adjustment available is a manual setting for the static transmit power at the Remote
Transceiver which may be used to optimize coverage, if necessary. This is a one time adjustment during set
up.
1.2.1 Basic Principles
The FiberDAS operation is based on an analog RF fiberoptic link. The principles are illustrated in Figure 1.
Input RF signals are converted to light by direct intensity modulation of a semiconductor laser. This
modulated light is transmitted over optical fiber and detected by a semiconductor PIN photodiode. The
photodiode converts optical power to electrical current. This current is AC coupled and passed through a
load to recover the RF signal.
The basic RF loss in this link is determined by the inefficiencies of the conversions of RF to optical and
back. The fiber also contributes an RF loss equal to twice the optical loss. This is because the photodiode
converts optical power to electrical current and RF power is proportional to the square of the current. So,
for 1 km of fiber with a loss of 0.4 dB/km (this is typical at 1310 nm wavelength) the optical loss is 0.4 dB
1-2
l
and the contribution to the
RF loss is 0.8 dB. In a real
installation, two optical
connectors will add
approximately 0.5 dB of
optical loss.
out
P (mW)
Opt ic al
Out put
in
P (mW)
Opt i ca
Input
The laser and, to a much
lesser degree, the
photodiode, add noise and
distortion to the RF signal.
This RF performance is
characterized just as any
RF link in terms of dB loss,
noise figure, third order
I
th
RF
Input
I (mA)
I
bias
RF
Out put (ac co upled
to remove dc component)
I (mA)
intercept, etc.
The fiber path itself can
contribute noise and
distortion. In the
Figure 1-1. Laser and photodiode characteristics.
LASER DIODE
CHARACTERI STIC
PHOTODIODE
CHARACTERI STIC
FiberDAS, the laser used is
a Fabry-Perot (FP) laser
instead of a Distributed Feedback (DFB). The DFB has a single spectral component. The FP laser has
multiple spectral components which can contribute noise and distortion for longer fiber runs. For the
distances used in the FiberDAS, this effect is not significant. Also, optical backscattering back into the
laser from less than perfect connections can cause additional noise and distortion. The FP lasers used in the
FiberDAS are much less sensitive to this than are DFB lasers. DFB lasers are also considerably more
expensive. However, if optical reflections are severe enough from a bad connection, the resulting optical
reflection may cause performance degradation even with FP lasers. To minimize this, SC/UPC optical
connectors with a return loss > 50 dB are used. Following standard practices in cleaning of the removable
optical connectors (see procedure outlined below) will keep the connections in spec and will avoid the
problems of performance degradation.
1.2.2 Functional Description
The FiberDAS Fiberoptic Antenna System connects to the mobile coverage RF ports of a repeater or base
station as an extended coverage antenna. The Hub Shelf mounts in a standard 19 inch rack close to the
repeater or base station transmit and receive RF ports. Generally, the appropriate configuration of the Entry
Shelf is used for convenience in combining multiple BTS channels, duplexing the signals to separate
Transmit and Receive, combining, setting the proper RF levels and routing the combined Tx and Rx
signals to and from one or more Hub Shelves, as necessary. The Hub Shelf RF connections are made via
the RF connectors on the rear panel. Inside the chassis, the transmit signal is split and routed to the Hub
Transceiver Plug-Ins. Each plug-in is a dual fiberoptic transceiver. The Hub Shelf holds up to eight plugins. Each plug-in interfaces with up to two Remote Transceivers by way of fiberoptic connections on the
Hub Shelf rear panel.
Transceiver optical output is the green connector. The Remote Transceiver units are generally mounted
above the false ceiling on a bulkhead or post. Each Remote Transceiver is connected to an indoor coverage
antenna by way of a customer-supplied flexible RF cable. Some indoor antennas are available with flexible
RF cable pigtails and an SMA connector termination. These units are distributed throughout the building or
campus as necessary to get full coverage. After installation, the transmit power from each Antenna Unit
may be adjusted manually by way of a rotary dip switch on the unit. This switch is indented in 2 dB steps.
This is a one time adjustment. For dual band units, there is a separate adjustment for each band.
1-3
Figure 1-2. System Block Diagram.
The block diagram of the FiberDAS Fiberoptic Antenna System is shown in Figures 1-2 and 1-3. The input
transmit RF signal is split eight ways in the Hub Shelf. Each of these signals is routed to a Hub Transceiver
Plug-In where it is split in two and each path modulates the optical output of a solid state laser diode. This
optical output is routed through a singlemode optical fiber to one Remote Transceiver. The photodiode in
the Remote Transceiver detects this optical signal and outputs a proportional electrical current. This current
is ac coupled and passed through a load to recover the RF signal. The RF signal is amplified, filtered and
output to the antenna.
Depending on design requirements, a 1:2 or 1:4 may be used at the antenna port to route the signal to 1, 2
or 4 in-building coverage antennas. Several versions of the Remote Transceiver are available that are
optimized for specific formats such as AMPS, GSM900, GSM1800, etc. Dual band versions are available;
one providing simultaneous coverage for GSM900 and GSM1800 and one for PCS1900 and 800 MHz. In
these versions, a single RF port feeds a dual band antenna.
The output RF signal path includes a variable attenuator that permits the user to adjust the output level in 2
dB steps for optimum coverage. The RF subcarrier from the plug-in is detected at the photodiode output.
This level is used by the transmit AGC to set the downlink gain. The subcarrier is also amplified and
inserted into the uplink path. This signal is detected at the Hub Shelf Plug-In for the uplink AGC and Node
Function Alarm which acts the primary critical failure alarm. A loss of RF signal due to plug-in or Remote
Unit laser failure, photodiode failure or a break in the fiber path will trigger this alarm. Also, a failure of
any amplifier in the downlink path in the Remote Transceiver, shuts off the subcarrier in the return path
which, in turn, triggers the Node Function Alarm at the Hub.
The receive or uplink RF signal from the antenna is filtered and amplified then routed to the Remote
Transceiver laser. A fast ALC is included in this path which prevents RF overdrive damage to the laser
while recovering fast enough to minimize blocking for TDMA and GSM signals. The laser output in the
Remote Transceiver is then modulated by the receive RF signal and is transmitted through another
1-4
singlemode optical fiber back to the Hub Shelf Plug-In. Each of the two photodiodes in the Hub
Transceiver Plug-In recovers the RF signals from each of two Remote Transceivers. The pilot tone on each
signal is split off and detected. This is used for the Node Function alarm. This LED is normally green and
turns red if the pilot tone is not detected. This alarm also appears at the Hub Shelf rear panel DB37
connector as a TTL level critical alarm. It would also be reported to the NOC or service technician by the
modem card depending on how the user configured the system alarms.
The receive RF signal from each photodiode is combined in the Hub Transceiver Plug-In. These combined
outputs are combined again in the and output to the rear panel RF uplink connectors. The Hub Shelf is
divided into two halves. The RF signals from each half are combined and routed to separate rear panel N
connectors. The combined uplink signals from one half can be routed to the BTS main receive port while
the other RF output is routed to the BTS receive diversity port. This method provides an overall 3 dB
system sensitivity improvement compared to routing all of the uplink signals into one receive port (see
Figure 1-2). Alternatively, both outputs may be combined and routed to a single BTS receive port.
Figure 1-3. FiberDAS RF path block diagram.
1-5
Figure 1-4. The Remote Transceivers are normally mounted above the false ceiling
but may be mounted in the room. Each Remote Transceiver is connected to the
Hub Shelf via 2 singlemode fibers. The Remote Transceiver is connected to a usersupplied antenna via flexible RF cable. The Remote Transceivers may be powered
using the optional universal Remote Power Supply with battery backup, or using a
central power supply that distributes DC power along with the fiber over a
composite fiber/conductor cable.
1-6
1.3 Specifications
Description
This specification defines the uplink and downlink performance of the FiberDAS Fiberoptic Antenna
System. The terminal equipment consists of the Remote Transceiver and the Hub Transceiver Plug-In. The
latter is installed in the Hub Shelf. This system meets the requirements for GSM900, DCS1800 and
GSM1900 Class M3 micro-BTS as well as IS-136 TDMA, IS-95 CDMA, CDMA2000 and UMTS for
wireless PBX, in-building and campus coverage applications.
There are five frequency options for the FiberDAS: 850 MHz (AMPS), GSM900, DCS1800, PCS1900 and
UMTS. There are two downlink output power options: the P1 power option meets GSM 900 micro-BTS
M3 requirements and is available for the 850MHz and 900MHz versions only when they are part of a dual
band system. The P2 power option meets micro-BTS M3 requirements for 1800MHz and 1900MHz. For
850MHz and 900MHz, the High Power meets GSM micro-BTS power class M1 requirements and IS-136
in-building requirements for +20 dBm composite power. All of these system standards specifications are
met for optical loss of up to 4 dB.
RF Parameters (up to 4 dB optical loss)
Uplink
Frequency Range 850 MHz 824 - 849 MHz
GSM900 890 - 915 MHz
DCS1800 1710 - 1785 MHz
PCS1900 1850 - 1910 MHz
UMTS 1920 – 1980 MHz
Amplitude Flatness
824 – 849, 890 - 915 MHz; (Any 15 MHz band) ± 1.0 dB
DCS, PCS, UMTS (Any 15 MHz band) ± 1.5 dB
Noise Figure ≤ 13 dB
Low Noise Option (DCS, PCS and UMTS only) ≤ 7 dB
Input Third Order Intercept (IIP3), 2 carriers, -43 dBm/carrier ≥ -15 dBm
Low Noise Option (GSM1800/PCS1900) ≥ -25 dBm
High Dynamic Range Option ≥ 0 dBm
High Dynamic Range Option w/Low Noise ≥ -10 dBm
Link Gain (with external 20 dB attenuator; 30 dB attenuator with Low Noise Option, over full
band and 4 dB optical loss range)
850 MHz, GSM900 4 ± 2.0 dB
DCS, PCS, UMTS 4 ± 2.5 dB
Uplink Input ALC
Input RF Threshold - 25 dBm
Low Noise Option -35 dBm
High Dynamic Range Option -10 dBm
High Dynamic Range Option w/Low Noise -20 dBm
Range 30 dB
Response Time < 5 µsec
Gain Stability ± 1 dB
Input/Output Impedance 50 Ω
Input/Output VSWR ≤ 2 : 1
Downlink
Frequency Range 850 MHz 869 - 894 MHz
GSM900 935 - 960 MHz
GSM1800 1805 - 1880 MHz
1-7
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