dual band presentation.pdf

8/11/2019 Dual band presentation.pdf

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Orange Technical GTF/CoE RA/IRS ,july 24&25th 2003 - 1

Training Sonatel MobilesDual band presentation

Fabrice Robin+33 1 55 22 11 36

[email protected]


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Agenda


Dual-band management principlesDual-band implementation strategySelection/Reselection principles

Alcatel handover algorithmDescription of the 3 main 1800 Mhz templates of Orange France

QoS indicators (examples from the operational unit of Paris)

Dual band network optimisation with GPRS


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Dual-band management principles

Dual-band implementation strategy


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Ti m e

Tra ff ic den s i t y

initial capac i ty

TRX add i tion / Sector isa t ion

Densif ica t ion

Funct ional i t ies : Concentr ic ce l ls , D irected re t ry, FRP , . ..

micro-cel ls

Band Ex tens ion : E - G S M , 1 8 0 0 , . . .

T raff ic de ns i ty Evolu t io n v s Ti m e a n d r a d io s o lu tio n s

Tra ff ic su bsc r ibe r s

evo lu t i on

N e t w o r k m a x c a p a c i ty d e v e l o p m e n t

Capacity handling solutions



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1800 layer: Field prediction & Capacity


1800 MHz frequency band usually larger than 900 MHz band> Large capacity> Frequency Planning much easier (more 1800 channels than 900 channels)

1800 channels propagation is lower than 900 MHz radiochannels

> Outside: 1800 field level is lower than 900 (roughly 6 dB to 10 dB )> Indoor : seems to be better 900 coverage

Dual-band versus mono-band Mobile Stations Ratio> low Dual Band MS ratio : the operator will force dual-band MS to the 1800 layer


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1800 cells : Implementation


Reuse of the 900 design> 1800 cells co located with the 900 cells

Try to have the same service area for 1800 and 900 cells> limited number of neighbouring declarations for the 900 and 1800 cells> for the 900 layer : reuse of the existing 900 neighbour declarations, completed by thecolocated and adjacent 1800 cells


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Traffic balance between 1800 and

900 layers


One access layer instead of two : better traffic handlingefficiency (1800 layer is the access layer)

Preventing the congestion of the 900 layer =>Dual band MS are directed and kept to the 1800 layer

> Idle mode: selection / reselection (C2 parameter)> PBGT Hand Over 1800/1800 rather than to the 900/1800

Preventing the congestion of the 1800 layer =>Directed Retry (Forced) to the 900 layer (assignation phase)


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Dual Band Strategy


900 Mhz layer for CoverageExisting network with very good coverageLayer to rescue 1800 Mhz emergency calls (quality, coverage reasons mainly)

1800 Mhz layer for Capacity New layer

Solution to reduce the congestion of the 900 Mhz layer


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Selection/Reselection principles


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Early Classmark Sending (Call setup)


Activation of the feature (GSM 04.08) on all BSCs and MSCs of

the network> tells to the Dual Band MS that during the call set-up phase, it should send a ClassmarkChange just after the CM service request, containing the information of band capabilities

(Classmark 3). This message is sent up to the MSC and follows the MS during all the

communication inter, intra BSC and inter, intra MSC

> MSCs and BSCs must know the dual band capabilities of the Dual Band MS

> The support of the Classmark 3 should be set by default on all the MSCs in the networkin order to authorise dual band capabilities after external HO

> On all BSCs to allow later HO on the 1800 layer during the call when the MS has initiateda call on a BSC far away from the dual band area


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IDLE mode : accessibility of the 2 bands


With dual band, no restriction for roamers who only have mono

band handset with the band not accessible

Parameters to be tuned to manage the band allocation onselection or reselection :

Cell reselect Offset CRO (describe on the next slide)

Cell reselect hysteresis CRH (application in Orange France in the LAC border)

Barred cell (inhibition of one layer, could be bad for customer, especially for roamers)


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Parameter : C2 (idle mode)


! The activation of the C2 parameters (per cell) allows to favour

the reselection on the 1800 cells even and while the signal

strength is bellow the 900 cells:

C2 = C1 + Cell_Reselect_Offset - Temporary_Offset * H(Penalty_Time-T)

H(Penalty_Time-T) = 0 when T > Penalty_Time

H(Penalty_Time-T) = 1 when T Penalty_Time


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Parameter : C2 (idle mode)


! The C2 parameter has an effect only if the cell is part of the 6

better channels measured by the MS.

! No consideration of band preference is possible in idle mode, of

course if the cell is not barred.


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C2 (idle mode) parameter on the 1800 cells


! CELL_RESELECT_PARAM_IND (cell basis): lock per cell that enable the

broadcast of cell reselection parameters on the BCCH of the cell (set to

true).! CELL_RESELECT_OFFSET (cell basis): set to 16 dB in Orange France (if no

GPRS). 1800 macro cells are favoured of 16 dB, Orange France consider

that the real value is 6 dB because the difference of propagation between900 and 1800 is estimated to 10 dB.

! PENALTY_TIME (cell basis): set to 0 = 20s in Orange France

! TEMPORARY_OFFSET (cell basis): set to 0dB in Orange France. No penalty

is applied on the 1800 macro cells

! RXLEV_ACCESS_MIN (cell basis): set to -99 dBm in Orange France for

1800 . The MS can camp on the 1800 macro cell only if the C1>0


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CRO values examples


In Orange France, some tests have been performed in 2002 forGPRS :

With nearly 100% dual band compatible MSBSS MotorolaCRH=8 dBTwin cells

With CRO = 16 dB -> 50% of the call init on the 1800 layer




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In dedicated mode : Multi-band reporting


Definition : Multi_band_reporting is a per cell basis broadcastparameter on the Sys_Info5ter layer 3 message indicating howmany cells of the opposite band must be measured among the6 neighbours in the Multiband Reporting :

0 : 6 neighbours of the best signal strength

1 : the best neighbour of the non serving band,the neighbours of the serving band, the othersneighbours per signal strength order

2 : the 2 best neighbours of the non serving band, the neighbours of the serving band, the othersneighbours per signal strength order

3 : the 3 best neighbours of the non serving band, the neighbours of the serving band,the othersneighbours per signal strength order


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In dedicated mode : Multi-band reporting


Orange France :Macro 900 and 900 : set to 1.Only one 1800 neighbour is sufficient to allows an HO on the 1800 layer without tocompromise the 900 neighbouring resources for HO.Macro 1800 : set to 3.

In order to favour the HO on the 1800 neighbours without to compromise a rescueHO on the 900 layer.

Remark : during idle mode the reselection process is onlyapplied on the 6 best neighbours measured by the mobile . Evenif the reselection process intends to favour 1800 macro inreselection, it will only work when 1800 macro is among the 6best.


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Alcatel handover algorithm


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Alcatel Algorithms (1/5)


Handover preparation consists of 2 different phases :1) Detection of the handover need (detection function by comparing the averagevalues with the thresholds)

2) Determination of the target cell list (evaluation function sorts the candidate cell)

Then T_filter begins : the target cell list is provided to the HO execution function

All the HO causes belong to 2 categories :Emergency causes

Comfort handovers


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Alcatel Algorithms (2/5) : Emergency causes


To differentiate the simultaneous alarms, all the causes have

priorities. In the less important priority order :UL Quality (cause 2)

DL Quality (cause 4)

UL Level (cause 3)

DL Level (cause 5)

Distance (cause 6)

Inner to outer for UL level (concentric cell and Single BCCH) (cause 10)

Inner to outer for DL (concentric cell and Single BCCH) (cause 11)


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Alcatel Algorithms (3/5) : Comfort HO


Comfort Hand Over :

Capture for the 1800 layer (Load of the serving cell is taken into account) (cause 21)

Capture from type upper to type lower, the speed of the MS have an impact in the decision

(Load of the serving cell is taking into account) (cause 14)Generalise Capture (parameters set with charge and traffic repartition) (cause 24)PBGT (Power BudGeT) (cause 12)Traffic HO (cause 23)

Outer to inner UL and DL level (concentric cell) (cause 13)Forced Directed Retry (cause 20)

The cause 24 is used for optimisation in Orange France.

In Micro presence, the cause 20 is generalised for the Alcatel 1800 and used in optimisationon the 900


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Alcatel Algorithms (4/6) : Determination of

the target cell list


The potential candidates list (except for an intracell HO) are sorted by the

evaluation function of the BSCIn a monoband network, the cell list consists of :

> All neighbouring cells in case of emergency HO

> The neighbours that verify the cause in case of better cell HO

In a dual band network, it is based on a hierarchical mechanism :

> A cell list is received by the evaluation function

> And also the prefered layer for the target cell (PREF_LAYER = none or upper or lower or upper+single)> And also the CELL_BAND_TYPE


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Alcatel Algorithms (5/6):

Evaluation of the candidate cells


Cells keeping in the list are placed in the order described below:

1) Case of emergency HO :

> Cells with CELL_LAYER_TYPE = PREF_LAYER .> Cells with growing order of PRIORITY(0,n).> Cells with CELL_BAND_TYPE = CELL_BAND_TYPE serving cell

> Ranking by ORDER or GRADE .> With presence of MS in outer area, HO to the serving cell.


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Description of the 3 main 1800 Mhz templates ofOrange France


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Dual-band management principle


Orange France has defined 3 major templates for 1800 cells :

> Umbrella template

> TWIN template

> Single BCCH template

And also :> Umbrella Macro 1800 modified to be compliant with TWIN or Single


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Umbrella template for 1800 cells


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Umbrella characteristics

TCH allocation


All the traffic is guided by assignment on the 1800 layer as much aspossible. To do this, the 1800 cells are in favour in idle with the C2 criteria inselection and reselection : CELL_RESELECT_OFFSET = 16 dB in Orange

France.

In communication , the traffic is taken from the 900 layer to the 1800 layer bycapture. Cross parameter threshold L_RX_LEV_CPT_HO(0,n) = -85 dBm in

Orange France.


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Umbrella characteristics

1800

900HO PBGT

HO by alarm


The communications stay on the 1800 layer as much as possible> HO between 1800 cells are only made by PBGT :

EN_MULTIBAND_PBGT_HO = DISABLE (but no matter because upper-lower PBGT HO impossible)

HO_margin(0,n) = 5 dB

The return to the 900 layer is only possible by alarm> Quality : L_RXQUAl_DL_H > 3.9 (offset : +1 if FH TS)

> DL level : L_RXLEV_DL_H < -98 dBm

> UL level : L_RXLEV_UL_H < - 107 dBm with diversity and - 104 dBm without diversity> Distance : U_TIME_ADVANCE > 4 (*550m)


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Alcatel settings


The 1800 cells is set as Mini , so CELL_LAYER_TYPE =

lower .

EN_PRIORITY_ORDERING = TRUE in all the network.

For cells with type lower , evaluation is made by ORDER .


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Emergency HO


List of neighbouring cells = all neighbouring cells, without 900 umbrella

macro cells which level thresholds is below of OUTDOOR_UMB_LEV(0,n) =

-95 dBm

PREF_LAYER = upper (because CELL_LAYER_TYPE= lower and

EN_RESCUE_UM=enable),

No PRIORITY(0,n) so the priority is for

the 900 umbrella macro cell

then the 1800 macro

then single + micros.

Cells ranking by ORDER = PBGT(n) - HO_MARGIN_XX(0,n).

Absolute filter of neighbours by RXLEVmin(n) = -98 dBm.


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Comfort HO


Forced Directed Retry is activated : EN_FORCED_DR = enabledIt allows to guide the communication from the 1800 layer to the 900 cells in case of queuing

Trafic HO is not activated (traffic is taken into account in PBGT(n) criteria)

No generalised capture, so the only case of comfort HO to consider is:

PBGT (only be done to other 1800 umbrella macro because the PBGT stay

in intra layer algorithm only).

The maintained neighbours which respect the PBGT conditions are ranked

with the rule ORDER = PBGT(n) HO_MARGIN(0,n).

Absolute filter of neighbouring cells by RXLEVmin(n) = -98 dBm


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TWIN Template for 1800 cells


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TWIN characteristics


Dual-band handsets proportion increase

The Dual-band MS will reach 100% in Orange France, so umbrella setting is not enough to

absorb all the 1800 traffic.

Evolution of the umbrella parameters

In order to improve the quality of the dual band network, new parameters need to be defined

in order to :

> improve the neighbouring management (reduce the number of neighbours to declare)

> Allow the interband PBGT HO and so on improve the QoS.


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Twin : two cells

> 1800 : BCCH and TCHs> 900 : BCCH and TCHs

Share the traffic between the two layers by threshold optimisation, andwithout hardware change (tilts)

Copy the 900 coverage to the 1800 coverage on the co-located sitesImprovement of spectral efficiency on 1800 with an equal radius of 900 cells

To have the nearer coverage on each band, Orange France put the same output power and

the same tilt in 900 and 1800 MHz (mechanical + electrical)

Neighbours of the TWIN 1800 cells : co located 900 cells, neighbour TWINand the 900 neighbours of the 900 co located cell

1800 MHz

900 MHz

BCCH

BCCH


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TWIN characteristics1800

900


1800 outgoing and incoming neighbours are copy to the 900 co located site.

1800 declaration is needed upper (to make PBGT HO with the 900 neighbouring cells). SoCELL_LAYER_TYPE = upper with Cell_type = umbrella at the OMC.

EN_PRIORITY_ORDERING = Enable.

To preserve a nominal comportment in case of emergency alarm, Priority(0,n) = 1 toward 900 isdeclared. Because otherwise, only the other TWIN cells would be sorted in priority in case ofemergency.

CELL_EV = GRADE (recommended for an upper cell type). ORDER is better recommended for lower cell (HO_MARGIN_XX(0,n) is used in that case in the case of interband PBGT HO)


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Selection / reselection on 1800 (idle mode) : C2 criteriumCELL_RESELECT_OFFSET = 16 dB for 1800 cells

Inhibition of 1800 capture : EN_PREFERRED_BAND = disable

HO from the 1800 to the 900 by PBGT criteria or comfort HO (better for voice

quality).The activation of inter layer PBGT is made at the cell level by the flagEN_MULTIBAND_PBGT_HO = Enable .

Cells must have the same cell_type.

Directed Retry (assignation)> 1800 => 900 Forced Directed Retry to avoid congestion of the 1800 layer EN_FORCED_DR = Enable> 900 => 1800 Directed Retry ( = on alarm only)


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With HO_MARGIN(0,n) = 16 dB , it roughly makes a difference of threshold received

of 9 dB (Rxlev_access_min = -102 dBm for 900 and -95 dBm for 1800).

The return to the 900 layer is possible by alarm> Quality : L_RXQUAl_DL_H > 3.9 (offset : +1 if FH TS)


> UL level : L_RXLEV_UL_H < - 107 dBm with diversity and - 104 dBm without diversity> Distance : U_TIME_ADVANCE > 4 (4*550m)

HO_MARGIN(0,n) = 16 dB or10 dB for a macro with fastMSPriority(0,n) = 1

HO_MARGIN(0,n) = 0 or 6 dBfor a rural macro with fast MSPriority(0,n) = 0

HO_MARGIN(0,n) = 5 dBPriority(0,n) = 0

1800

900

Cross parameters



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Emergency HO


PREF_LAYER = upper + single (CELL_LAYER_TYPE= upper)

Without Priority (0,n) modification, the TWIN cell would sort inpriority the other TWIN cells

Not efficientSo Priority (0,n) = 1 to favour emergency HO towards 900 cells

GRADE evaluation (PBGT ranking with neighbour load

information)


f


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Comfort HO


Activation of inter band PBGT from 900 cells toward all Twins

neighbouring with HO_MARGIN(0,n) = 0 dB.

Inhibition of 1800 capture : EN_PREFERRED_BAND = disable .

PREF_LAYER = none

Priority (0,n) = 1 towards 900 cells

GRADE evaluation (upper)


l l i


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TWIN template conclusion

Advantages Drawbacks Same neighbours declaration for the 1800 and the 900

Interband Ho generates numerous Ho if the 1800 plate issmall

Cell by cell deployment possibleTraffic balance : to be tuned by the neighbour parameters

settingSame counters & indicators for the 1800 layer (like 900) Isotilt 900/1800 required

Interband HO on PBGT Umbrella template on several cells impossible

Better spectrum efficiency on the 1800 layer because ofthe better uniformity of the cells

Pas de TWIN en B5


Expected results on Twin parameter against


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p p g

Umbrella parameter


Lower blocking on the 1800 layer due to the service area

diminution

Improvement of the vocal quality because :The service area is shorterHO can also be made by PBGT and not only because of bad radio conditions


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Single BCCH

Si l BCCH


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Single BCCH


!

Same principles as the concentric cells

! Only one cell with one 900 BCCH and TRXs 900 and 1800, no 1800 BCCH> 1 Outer area on 900> 1 Inner area on 1800> each TRX is allocated at one area

! BCCH ,CCCH, et SDCCH channels must be on the Outer area on 900 .The PDCH also (Orange France decision on B6 for Alcatel).

! Queuing is possible only on the Outer area! Directed Retry can be made only on the Outer area! Direct allocation of TCH on the Inner area if the threshold level measured on SDCCH

is better than thresholds fixed on template, on UL and on DL at the assignation, with

incoming HO on DL

1800 MHz 900 MHz

BCCH

Si gl BCCH t l t


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Single BCCH template


Cells are declared as oncentric : CELL_PARTITION_TYPE=Concentric

Single BCCH : FREQUENCY_RANGE = GSM-DCS

EN_MULTIBAND_PBGT_HO = Enable

if the MS is in the inner zone, 900 level extrapolated from the 1800 levelOFFSET_HO_MARGIN_INNER : 10 dB (average propagation offset between900 and 1800) applied.

ZONE_TYPE = 0 (resp. 1) outer TRX (resp. inner TRX)

Single BCCH cells are monitored as a macro 900 cell in terms of priority andeligibility

Single BCCH parameter setting


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Single BCCH parameter setting

HO Inner towards Outerif DL < -94 dBm

PBGT :to another Single BCCHor to a Macro 900,

if its mean level is 5 dB higher

1800

900

Incoming HO:direct assignation on 1800 inner if mean DL level reception from the originating cell > -82 dBmotherwise: assignation on TCH 900.

Call initiation:direct assignation on TCH 1800

if UL > -107 dBm nd DL > - 82 dBmotherwise: TCH 900

HO Outer towards Inner if UL > -107 dBm nd DL > -82 dBm

Intercell HO if DL < -95 dBmor UL < -97 dBm

intercell HO if

UL < -97 dBm

PBGT :to another Single BCCH or to a Macro 900,

if its mean level is 18 dB higher


Single BCCH


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Single BCCH


To avoid ping pong HO between layers : ZONE_HO_HYST_DL = 12 dB

Functionality descriptionIntracell HO 900->1800 :

This mechanism is identical to the concentric cell algorithm but the Timing Advance condition is not checked for dual band

cells sites.

Intracell HO 1800->900 :

In case of lack of resources in the Outer GSM 900, the dual band MS stays on the inner 1800 TRX till it finds a GSM 900 or

1800 neighbouring cell which satisfies the conditions for PBGT, RXQUAL, RXLEV or DISTANCE (interferences HO inhibited).

PBGT HO from inner to outer not forseen

Alarm thresholds :> Quality : L_RXQUAl_DL_H > 3.9 (offset : +1 if FH TS)


> UL level : L_RXLEV_UL_H < - 97 dBm

> Distance : U_TIME_ADVANCE > 19 (*550m)

Single BCCH template conclusion


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Single BCCH template conclusion

Advantages Drawbacks

Only one CI, one cell to the OMC and in the SI Investment cost : needs for G3 or G4 multiband BTS

Deployment : 1800 cells can be deployed one by one Large band repeaters => no 900 repeaters

Frequency planning : 1800 frequency for TCH only Aerials : same tilt for 1800 and 900 antennas

SFH : frequency hopping on the whole 1800 bandQoS monitoring : NO specific counters to the 1800 cell(congestion, drop calls)

Parameter setting : only for the 900 cell (less neighboursto be declared) Access : roamers with only mono band 1800 handsetscan't access to the network

Increase of the 1800 capacity (BCCH TS,.)BTS activation one by one (1 hour), with site moving and10 minutes off

Less neighbours to be declared -> better BCCH

neighbour level estimation in idle -> TCH assign secured



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Umbrella macro 1800 modified



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To become compatible with new eventual Twin or Single BCCHneighbouring.

Modifications to set :1800 macro as upper (Cell_type = umbrella)

> So that PBGT toward Twin or inner area is possible> Priority changes from 0 to 1 toward the 900 neighbours, to keep the current behaviour for emergency HO.

Otherwise, the QoS of this lower cell would not be optimum (no PBGT HO with1800 TWIN or inner area of single).

An activation by PRC takes a long time, it is necessary to find a way to makeit automatically

Dual-band availability on Alcatel


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Dual-band availability on Alcatel


B5.1 for Alcatel BSS

Single BCCH :> BSS B6.2 on 25i for on optimal work

on Alcatel with BSC G2 - BTS Evolium (G3 or G3.8 or G4.2) => available

> BSS B7 to be able to monitor at the TRX level single BCCH cells


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QoS indicators used(examples from the operational unit of

Paris)

Alcatel Ho causes without Ho better cell


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900 Mhz layer Alcatel Ho causes repartition without Ho better cell - 900 layer (3214 cells)

0

5

10

15

20

25

30

2 0 0 2

- W 1 0

2 0 0 2

- W 1 2

2 0 0 2

- W 1 4

2 0 0 2

- W 1 6

2 0 0 2

- W 1 8

2 0 0 2

- W 2 0

2 0 0 2

- W 2 2

2 0 0 2

- W 2 4

2 0 0 2

- W 2 6

2 0 0 2

- W 2 8

2 0 0 2

- W 3 0

2 0 0 2

- W 3 2

2 0 0 2

- W 3 4

2 0 0 2

- W 3 6

H O c a u s e s

( % )

0

10000000

20000000

30000000

40000000

50000000

60000000

70000000

N u m

b e r o

f H O

HO_DRNb_HO%CAP_MICRO

%CAP_1800%TRAFIC%DIST%ULS%DLS%ULQ

%DLQ


Alcatel Ho causes 900 Mhz layer


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Alcatel Ho causes repartition - 900 layer (3214 cells)

0

5

10

15

20

25

30

35

2 0 0

2 - W 1 0

2 0 0

2 - W 1 2

2 0 0

2 - W 1 4

2 0 0

2 - W 1 6

2 0 0

2 - W 1 8

2 0 0

2 - W 2 0

2 0 0

2 - W 2 2

2 0 0

2 - W 2 4

2 0 0

2 - W 2 6

2 0 0

2 - W 2 8

2 0 0

2 - W 3 0

2 0 0

2 - W 3 2

2 0 0

2 - W 3 4

2 0 0

2 - W 3 6

H O c a u s e s (

% )

0

10000000

20000000

30000000

40000000

50000000

60000000

70000000

N u m

b e r o

f H O

HO_DR

Nb_HO

%CAP_MICRO

%CAP_1800

%TRAFIC

%DIST

%ULS

%DLS

%ULQ

%DLQ

%Better _Cell


Alcatel Ho causes without Ho better cell


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1800 Mhz layer Alcatel Ho causes repartition without Ho better cell - 1800 layer (1967 cells)

0,00%

5,00%

10,00%

15,00%

20,00%

25,00%

2 0 0 2 - W

1 0

2 0 0 2 - W

1 2

2 0 0 2 - W

1 4

2 0 0 2 - W

1 6

2 0 0 2 - W

1 8

2 0 0 2 - W

2 0

2 0 0 2 - W

2 2

2 0 0 2 - W

2 4

2 0 0 2 - W

2 6

2 0 0 2 - W

2 8

2 0 0 2 - W

3 0

2 0 0 2 - W

3 2

2 0 0 2 - W

3 4

2 0 0 2 - W

3 6

H O c a u s e s

( % )

0

5000000

10000000

15000000

20000000

25000000

30000000

35000000

40000000

45000000

N u m

b e r o

f H O

DR_FORCED

Nb_Total

%HO_CAP_MICRO

%HO_CAP_1800

%HO_TRAF

%HO_Dist

%HO_ULS

%HO_DLS

%HO_ULQ%HO_DLQ




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Alcatel Ho causes repartition - 1800 layer (1967 cells)

0,00%

10,00%

20,00%

30,00%

40,00%

50,00%

60,00%

70,00%

2 0 0

2 - W 1 0

2 0 0

2 - W 1 2

2 0 0

2 - W 1 4

2 0 0

2 - W 1 6

2 0 0

2 - W 1 8

2 0 0

2 - W 2 0

2 0 0

2 - W 2 2

2 0 0

2 - W 2 4

2 0 0

2 - W 2 6

2 0 0

2 - W 2 8

2 0 0

2 - W 3 0

2 0 0

2 - W 3 2

2 0 0

2 - W 3 4

2 0 0

2 - W 3 6

H O c a u s e s

( % )

0

5000000

10000000

15000000

20000000

25000000

30000000

35000000

40000000

45000000

N u m

b e r o f

H O

DR_FORCEDNb_Total%HO_CAP_MICRO%HO_CAP_1800%HO_TRAF%HO_Dist%HO_ULS%HO_DLS%HO_ULQ%HO_DLQ

%HO_better_cell



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Dual-band network optimisation with

GPRS


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Dual-band and GPRS


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The GPRS transfert drop duration during a reselection is several

seconds.Each reselection causes a throughput decrease (so also GPRSQoS).

In a dual-band environnement, the neighbours are numerous.There is a risk of degrading the GPRS QoS in Dual-band environnement

The GSM setting has an impact on the GPRS QoS because theGPRS cell selection/reselection is the same as the GSM one

Optimisations


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p


CELL_RESELECT_HYSTERESIS : 4dB -> 8 dBTo reduce the number of intra-band reselections

8 dB used in dense urban and urban environnement6 dB (optimised value) can be used for the LAC border cells4 dB remains the rural value

Favouring the access to the 900 layer (CELL_RESELECT_OFFSET = 0dB)In some cases, particularly in indoor, 900 coverage is better than 1800 coverage.By favouring the 900 layer for the selections/re-selections and by capturing the voicecommunications to the 1800 layer, GPRS MS stay on the 900 layer.Reserved TS only on the 900 Mhz layer and maybe some dynamic TS on the 1800 layerStrong capture algorithm on the 1800 layer to avoid 900 saturation

CELL_RESELECT_OFFSET : 16 dB -> 20 dBWith RxLevAccess_Min=-95 dBmThis is the best solution to optimise the GPRS performance and not to decrease the circuitQoS.

In that case, static TS must be reserved in both bands

Conclusion


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In dense urban and urban, with TWIN and RxLevAccessMin = -

95 dBm, the Orange France recommendations are :CELL_RESELECT_HYSTERESIS = 8 dB , but 6 dB or optimised value can be usedfor the LAC border cellsCELL_RESELECT_OFFSET 1800 = 20 dB

The use of the 900 layer for circuit and GPRS access cant beused in environement with micro cells because of the risk ofsaturation for the 900 layer.

Moreover the 900 layer load increases whereas the 1800spectrum is the largest

So this solution is not used in Orange France


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Thank you

Bibliography


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Alcatel B6.2 AQ 25i-6 parameter setting in Orange France

Ref : Orange France/DOD/DAT/RRA/02.11/JMB

Alcatel Algorithms B6.2Ref : Orange France/DTRS/DRA/CPR/03.91/FRO

Stratgies de paramtrage TWINRef : FTM/DOD/DTFI/TCE/01.211/JMB

Compte rendu des zones radio GPRSRef : OF/DOD/RRA/A&F/02.206/PG

dual band presentation.pdf

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