Dual Band Network

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Dual Band Network

Presented by: Mansoor Shahid Date 29.08.2008

Dual Band FeaturesDual Band Features


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Definition


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Definition

A cell is defined as dualband if GSM900 TRXs and DCS1800 TRXscoexist and share the same BCCH.


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PrincipleDefinition


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Principle

The principle of the Dual Band cells is to share the resources in both

zones assuming that the TRXs are transmitting at different power.

The dual band combining into one cell allows to save up to oneSDCCH in particular


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Features


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GSM900 and GSM1800 features

DCS1800 has a smaller coverage than GSM900.

DCS1800 has more ARFCN than GSM900.

GSM 900 GSM 1800

Frequency band 890...960 MHz 1710...1880 MHz

Number of channels 124 374

Channel spacing 200 kHz 200 kHz

Site type Radius (approx.) Path loss

Macro cells (radius>3 km) >3 km 1800MHz>900MHz by 12.8dB

Macro cells 0.3-3 km 1800MHz>900MHz by 12.5dB

Micro cells Along streets 1800MHz>900MHz by 6dB

900

1800900MHz radio has a bigger

penetration loss than 1800MHz


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Network Structure


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Different dual band network structures

Separated MSC network Shared MSC network Shared BSC network

MSC MSC

BSC BSC

900

BTS

1800

BTS

MSC

BSC BSC

900

BTS1800

BTS

MSC

BSC

900

BTS

1800

BTS

900/1800

BTS


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Separated MSC Network

Location updating Easy to happenHandovers between GSM900 and DCS1800 will be inter MSC handovers

1800 cell

900 cell

900 cell

1800 cell

LAC1

LAC2

BSC BSC

MSCMSC

BSCBSC BSC

MSC


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Shared MSC network

Location updating NOT easy to happen

Handovers between GSM900 and DCS1800 will be inter BSC handovers

1800 cell

BSC

900 cell

BSCBSC BSC

1800 cell

900 cell

LAC2LAC1

MSC


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Shared MSC/BSC network

BSC BSCBSC BSC

1800 cell

900 cell

1800 cell

900 cell

LAC2

LAC1

MSC

Location updating NOT easy to happenHandovers between GSM900 and DCS1800 will beintra BSC or inter BSC handovers


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Capabilities


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1.1Improved radio environment and traffic capacity:

There are several restrictions on the usage of features BTS Power Controland Frequency Hopping on the BCCH frequency. By omitting the BCCHfrom one of the frequency bands in a multi band cell, these restrictions nolonger apply.

Capabilities


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Single band cell / multi band site (left) vs. multi band cell (right), radio performance

Also, there is one more timeslot available for traffic in the non-BCCHfrequency band, since the BCCH is omitted.

Cont
http://edw/alex?ac=image&fn=104_1553-HSC10312_4Uen.C-Radio.pdf


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1.2Reduced Number of Defined Cells and NBR Relations

The number of defined cells and cell network is reduced after the

conversion of the same network based on the single band cell /multi band site concept. Defined neighbor relations can besignificantly reduced in areas where the most of the cells are multiband. This reduction can easily reach 50% or more.
http://edw/alex?ac=image&fn=104_1553-HSC10312_4Uen.C-LessNR.pdf


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Handover for Dual Band Cell


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Concentric Cell Parameter Definition


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On SDCCH (always in the large zone), when the serving cell is either a dual

band cell the call can be directed to the inner zone.

The small zone (or band1) is eligible when the following conditions aresatisfied:

RxLevDL > concentAlgoExtRxLev

MS_BS_Dist < concentAlgoExtMsRange(timing advance criterion)

Only one TA measurement is done for concentric cells.

Direct TCH Allocation


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Cont:


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External cell list of BSC1 consists the information of cell6 and cell 7:

CGI, cell layer, BCCH, BSIC and handover parameters(vender1).

Handover from one BSC to another

2

3

1

4

5

9

10

8

6

7

BSC2BSC1

BSC1 vender1

Internal cell listCell 1

Cell 2

Cell 3

Cell 4

Cell 5

External cell list

Cell 6

Cell 7

Internal cell listCell 6

Cell 7

Cell 8

Cell 9

Cell 10

External cell list

Cell 4

Cell 5

BSC2 vender2


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Value in PTML Network

There are about 5 standard values set in Nortel Region.

ConcentAlgoExtRxLev ConcentAlgoIntRxLev

16 11

20 11

23 11

26 11/16

30 20


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Cont

BIZONEPOWEROFFSET(N)(AdjacentCellHandoverObject)

biZonePowerOffset(n) in adjacentcellHandover object reflect thedifference of propagation between the two zones of an adjacent cell incase of handover towards the inner zone.

When attempting a Handover directly to the inner zone of an adjacentcell EXP2xx(n)=hoMarginxx(n) + biZonePowerOffSet(n) >0 shall berespected.

biZonePowerOffset(n) = concentAlgoExtRxLev(n)rxLevMinCell(n)


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Dual band network problems and solutions


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Dual band network problems and solutions

Problems: Unexpected location updating signaling for Um interface and other interfaces

Handover between GSM900 and DCS1800 cells not under control

Traffic load sharing problems

Recommended solutions: Utilize the separated MSC network structure and proper LAC allocation Utilize proper handover parameters

Optimize handover settings to achieve proper traffic load sharing


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Benefits


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Main benefits of dual band cell functionality are:

The number of cells to configure and monitor is roughly divided bytwo.

No BCCH pattern has to be defined in the second band.

Slight increase in capacity: one TS saving+DCS and GSM DRXs in onepool, which provides more network control of the traffic distribution.

Intra cells Handover between DCS and GSM DRXs of a same cellinstead of synchronous inter cell handovers reduce the muting timeand probability of drop call.


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Summary


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Summary:

In a Dual band cell it is possible to configure two different frequencybands in a cell with only one BCCH.

BCCH configured on a frequency Band called BCCH band and theother Band is called Non-BCCH Band.

Non-BCCH band used to provide more capacity to be used for traffic.

In case of GSM900 and DCS1800 co-location, the GSM900 has strongsignal strength but we canuse the idle parameter setting and layer

handover to control the traffic and achieve the balanced trafficbetween GSM900 and DCS1800


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Thanks

Dual Band Network

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