01_PWAV Repeater Basic Jul2008

7/27/2019 01_PWAV Repeater Basic Jul2008

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Bi-directional Amplifier Amplifies and transmits signals in both directions


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Basic Repeater Application


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-Off Air application

Rep.


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Basic Repeater Application-Fibre optic application 1

RepeaterMaster

Unit: (RMU)


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-Fibre optic application 2

RepeaterMaster

Unit: (RMU)


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Eliminate Coverage Holes


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Eliminate Coverage Holes Cont.


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Hybrid Networks Continue


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Distributed System

Difficulties getting space where you want to putyour BTS

The repeater can be put outdoors

No need for Air Conditioned room

Small space

Remote operation and maintenance

Distribute capacity to several locations


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Distribution of Capacity


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Centralized


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Conclusion, Trunking Gain

De-Centralized Centralized

( BTS solution ) ( Repeater solution )Erlang required 32E 32ENo. of TCH required 59 41No. of TRX required 12 6No. of BCCH+SDCCH required 9 3

No. of TCH available 87 45

i.e. Trunking gain achieved with a repeater solution


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Target Areas


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Modular design enables easy upgrading and services

Easy upgrading from 2 to 8 carriers for GSM/EDGE and to4 carriers for CDMA/WCDMA

Separate power amplifiers for uplink and downlink

Remote control via wireless and/or wired line modem

Automatic supervision of the antenna isolation

MTBF > 50 000 hours

Features of Powerwave Repeaters


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Antenna Isolation

Gain

Feedback oscillation / antenna isolation

Maximum output power / minimum input power

Noise /interference level in the system

Number of donor channels

Timing

Delay spread

Timing advance

Site Design Considerations


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Antenna Isolation


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Antenna Isolation Cont.


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Choice of donor-site !

High front to back ratio !



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At least Gain of repeater + 10dB (margin)*

Achieved by :

Right choice of antennas

- Opening angle

- Front to back ratio Right choice of donor BTS (direction)

Right placement of antennas (vertical spacing)

*13dB for channel-selective repeater

Antenna Isolation (Summary)


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EDoPL


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Off air repeater gain setting concern

Antenna Isolation

Gain < isolation - 10dB

Repeater max. output power DL Gain < rated repeater max. output repeater input

Repeater uplink noise

UL Gain < EDoPL 10dB


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Antenna Isolation Supervision

(GSM Channel-Selective)


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Gain and Noise


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Gain should be less than repeater max. output power minusrepeater input

If the amplifier is saturated, AGC should reduce the repeatergain. Otherwise the repeater will perform very badly interms of distortion and thus generates unwanted IM.

(In the case of CDMAOne, the power level of pilot signal is1/5 of the max. total channel power. For example, if only

the pilot is present during installation, the repeater downlinkgain should be set to at most: max. repeater output power repeater input 7dB)

DL Gain and Noise


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UL Gain, EDoPL and Noise


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The GOS will be drastically reduced in the repeatercovered area if not all the carriers in the donor cell are

repeated. It is thus important that all the carriers in thecell has the same coverage.

Number of Donor Carriers


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Delay spread (time dispersion) must be less than 15 s for aGSM system. Placing the repeater between the donor BTS

and the area to be covered satisfies this requirement. CDMAsystems are in general more robust to delay spread.

For GSM, the timing advance has a maximum limiting thedistance between the BTS and the mobile to 35 km.Introducing a repeater reduces this maximum distance 1.5km to 33.5 km (normally not significant).

Timing Considerations


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01_PWAV Repeater Basic Jul2008