2. • Importance of In-Building Solution
• Distributed Antenna Systems (DAS)
• In-Building Design Procedure
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3. There are many reasons for the mobile operator to provide sufficient
in-building solutions:
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4. - Why is In-building Coverage Important?
• Overcome the Orthogonality Degradation
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5. Power Capacity
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6. - Why is In-building Coverage Important?
• Overcome the Orthogonality Degradation
• Decrease the PLPU
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7. - Effects of PLPU and Orthogonality on the System:
Distance (m)
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8. - Why is In-building Coverage Important?
• Overcome the Orthogonality Degradation
• Decrease the PLPU
• Overcome the Soft Hand Over Load
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9. The major effect of the soft handover that the network
will be loaded by a factor of 2 – 3 times
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10. There are many different approaches to how you can design an
indoor coverage system with uniformly distributed coverage
level:
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11. Passive DAS:
Passive DAS Passive Components
• Coaxial Cables
Advantages Disadvantages • Splitters
• Tappers
Not flexible for
Easy to Design
Upgrades
• 3 dB Coupler
Components Low Data • Attenuators
Compatibility Performance
• Dummy Loads
Can be installed in
Harsh Env.
High power BTS • Circulators
• Filters
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12. Passive Components
• Coaxial Cables
Typical attenuation of coaxial cable per 100 m (dB)
Cable Type 900 MHz 1800 MHz 2100 MHz
¼ inch 13 19 20
½ inch 7 10 11
⅞ inch 4 6 6.5
1 ¼ inch 3 4.4 4.6
1 ⅝ inch 2.4 3.7 3.8
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13. • Splitters
Used for splitting one coax line into two or more lines, and
vice versa. When splitting the signal, the power is divided
among the ports.
4-Way Splitter
1:2 1:3 1:4
If splitting to two ports only half-power minus the insertion
loss, typically 0.1 dB 3-Way Splitter
Loss through the splitter:
Splitter loss = 10 log (no. of ports) + insertion loss
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2-Way Splitter
14. • Tappers
Tap splitters are used like splitters, used to divide the
signal/power from one into two lines.
The difference from the standard 1:2 splitter is that the power is
not equally divided among the ports.
This is very useful for designs where you install one heavy main
cable through the building, and then „tap‟ small portions of the
power to antennas along the main cable.
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15. • Attenuators
Attenuate the signal with the value of
the attenuator.
Standard Attenuator
Port 2 = Port 1 - Attenuation
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16. • Dummy Loads or Terminators
Terminators are used as matching loads on
the transmission lines, or any „open‟
or unused ports on other components.
Standard 50 Ω dummy load or terminator
Terminator used as matching load on the circulator
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17. • Circulators
The circulator is a nonreciprocal component
with low insertion loss in:
forward direction (ports 1–2, 2–3 and 3–1) and,
high insertion loss (ports 2–1, 3–2 and 1–3)
in the reverse direction.
Standard Circulator
The insertion loss in the forward
direction is typically < 0.5 dB and in the
reverse direction > 23 dB .
Usage:
The circulator can be used to protect the port of a
transmitter against reverse power from reflections
caused by a disconnected antenna or cable in the
antenna system.
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18. • 3 dB Coupler
The 3 dB coupler is mostly used for combining signals
from two signal sources. At the same time the coupler
will split the two combined signals into two output
ports. This can be very useful when designing passive
distributed antenna systems.
Typical 3 dB Coupler
A 3 dB coupler used as a two-port combiner Combining two TRX and splitting out to a
distributed antenna system
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19. • Filters
o Duplexer
The duplexer is used to separate a combined TX/RX
signal into separate TX and RX lines.
o Diplexer
The diplexer will separate or combine whole bands
from or with each other
o Triplexer
A three band version that can separate or combine
900, 1800 and 2100 MHz is also available, called a
Triplexer.
Typical Filters
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20. Sample of Passive
DAS Diagram:
Elevator Shaft
Elevator Shaft
Elevator Shaft
Tapper
Splitter
Coaxial
Cable
Base
Station
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Antennas
21. Active DAS:
Active DAS Active Components
• Main Unit (MU)
• Expansion Unit (EU)
Advantages Disadvantages
• Remote Unit (RU)
Easy to Design
Limited • Optic Fiber Cables
Environments
• IT Cables
No need for High
Power
Better Data
Performance
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22. • Main Unit (MU):
o The MU is the „brain‟ of the system.
o MU distributes the signals to the rest of the
system via expansion units (EU).
o The MU will typically be connected to the (EU)
by optical fibers.
o Monitor the performance of the DAS system.
o In the event of a malfunction or a warning it is
able to send an alarm signal to the base station.
o Remotely manageable, configurable and
monitored.
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23. • Expansion Unit (EU):
o EU converts the optical signal from the MU to an
electrical signal and distributes this to the RU.
o EU feed the DC power supply to the Remote
Units (RU) via the existing signal cable.
o EU is connected to the MU using optical fibers.
o Typical distance of the optic fiber cable between
the EU and MU is up to 6 km.
o EU is connected to the RU‟s using IT cables.
o Typical distance of the IT cables between the
EU and RU is up to 400 m.
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24. • Remote Unit (RU)
50 Ω Coax
o Converts the signal from the EU to radio signals.
o Also converts the signal from mobiles into
electrical signals and back to the EU.
o Installed close to the antenna in order to
improve the link performance and to keep the
passive losses to minimum.
Omni Antenna
50 Ω Coax
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25. Sample of Active DAS
Diagram:
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26. • Hybrid DAS:
o A „hybrid‟ DAS is a mix of an active DAS
and a passive DAS.
o Antenna supervision nonexistent.
o Limit the installation possibilities.
o Limit the links performance.
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27. Sample of Hybrid DAS
Diagram:
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28. Design Proposal:
1. Floor Plans:
Indicates the exact
locations of the
antennas, proposed
feeders routing, splitters
locations and the
equipment room location
in “Autocad” format.
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29. 2. Site Survey and Measurements
A survey should be done to check the following points:
• The equipment rooms locations.
• Riser and cable routing.
• The exact locations of antennas and false ceiling.
• Nature of walls if it is made of concrete ,gypsum
, wooden boards or glass.
Tests to be done during the measurements:
1. Walk Test
2. Simulation Test
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30. Walk test Simulation Test
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31. 4. Capacity and Traffic analysis
To assign the required resources, expected traffic at the peak hour
needs to be considered taking into consideration the following
parameters:
• User weight (traffic/subscriber)
• Operator market sharing
• Future expansion
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32. 4. EIRP Table or Link Loss:
Indicates the output power at each individual antenna in the
RF distribution system.
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33. 3. System Schematics:
Indicating how antenna
2nd Floor
system is being
distributed to various
parts of the building and
marking the equipment.
1st Floor
Symbol Description
Omni Antenna
2-Way Splitter
Ground Floor
BTS on
Ground Floor
3-Way Splitter
4-Way Splitter
Lower Ground
⅞” Coaxial Cable
½” Coaxial Cable
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34. Example of Design Considerations:
1. Place the hot spot antennas and
maximize the data performance.
2. Maximize the coverage of each
antenna.
3. Isolate the building.
4. Fill in the gaps.
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35. The Link Budget
Is the fundamental calculation for planning
of any RF link between a transmitter (Tx) and
a receiver (Rx).
• The simplest LB calculation looks, in principle, like this:
Rx Level (dBm) = Tx Power (dBm) + Cable Attenuation (dB)
Propagation Losses + Antenna Gain (dB)
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Hinweis der Redaktion
It is very important to terminate all ports on the splitter; do not leave one portopen. If it is unused, terminate it with a dummy load.
Walk test to discover the areas of poor coverageSimulation test to verify good coverage
The result of the link budget calculations is the maximum allowable path loss (APL) fromthe base station to the mobile in the downlink and the maximum allowable link loss on thereverse link, from the mobile to the base station the uplink.In two-way calculations we actually have two LBcalculations, one for the DL and one for the UL.Components of LB:a, BS power (dBm): this is the generated RF power from the base station, at the antennaconnector of the output of the base station rack.b, Feeder loss (dB): this is the attenuation of the coax cable from the BS to the antenna.The loss is symmetrical for the UL and DL.c, BS antenna gain (dBi): this is the antenna gain (directivity) of the BS antenna.d, EiRP (dBm): effective isotropic radiated power – this is the radiated power from thebase station antenna. It is BS power feeder loss þ antenna gain.e, MS antenna gain (dBi): the mobile terminal antenna has a gain that we need to includein the LB. This antenna gain may in fact be negative! There are many measurements