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Dualband Network Description (1)


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Dualband Network Description (2)

71% GSM900 only Sites 3% GSM1800 only Sites

26% Dualband Sites 72 x GSM1800 Channels; 36 x GSM900 Channels GPRS configured for both GSM900 and GSM1800 cells

GSM1800 - 3G neighbours defined one way only.o Nortel 18003G and 9003G 3G900 Onlyo Nokia 18003G and9003G 3G900 Only


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Background and Dualband Strategy (1)

Idle Mode:o Call setup on GSM900 primarilyo 4dB bias for GSM1800 => Reduce load on

GSM900


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Background and Dualband Strategy (2) Dedicated Mode:

o Ho From 900 to 1800 (-15 PBGT Margin)

o Stay on 1800 (+ 15 PBGT Margin back to 900)


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Dualband Network Performance (1)


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E.g. Kathrein 742264:

Dualband Antenna Similar Horizontal

patterns Significant variation in

differencefor Verticalpattern.

Comparison of Hermitage_A and Hermitage_X_ADualband X-Polar Antenna (ADC antenna type DFX_MN_70_13_0_0)Antenna for Each Band has

o Equal height & Same mountingo Equivalent line-of-sight coverage areaso Equal bearing and Tilt (mech. = 0 and elect. = 0)

Horizontal Vertical

COMPARE: GSM1800 Levels & GSM900 Levels


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Rolling Ave Of 8 Meas Results

GSM900 12dB stronger than corresponding GSM1800 (average) Standard Deviation: 5.5dB 10% of cases GSM1800 > GSM900

Nortel Dualband Cell / Nokia Common BCCH (4)

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Difference Between UL Lev and DL Lev

=> Different for Nokia & Nortel=> Different for GSM900 and GSM1800

UL and DL Level Analysis

Differences Due to Tx Pwr and Rx

Sensitivity, Ref Point, etc.

=> May Still be Balanced

=> RxQual Evaluates UL and DL


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Nortel Level Handover


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NORTEL

RxQual>HO Qual Threshold

HO Qual Threshold = 5

=> 3.2% to 6.4% BER

I.e. BER>6.4%, then Quality HO

NOKIA

RxQual>=HO Qual Threshold


=> 3.2% to 6.4% BER

I.e. BER >=3.2%, then Quality HO

HO Quality Thresholds Comparison


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Quality HO Averaging

Nortel:

RxQual > 5, averaged over 8 Meas Reports Averaged in BER

(Note: 7 out of 8 RxQual Measurements = 5 will not trigger a HO)

Nokia:

RxQual >= 5, for 4 out of 6 measurements, (px, nx)

=> Very easy to trigger a Qual HO in Nokia

Also, Qual Margin = -2 dB => 900 - 900 handing over to something weaker!

(~20% of Nokia 900 HO = UL & DL Qual)


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Urban => Dualband 72 x GSM1800 Channels; 36 x GSM900 Channels

Bias of 4dB for GSM1800 => Idle and Call Setup on GSM900 900->1800: -15 dB Margin => HO to 1800 immediately GSM1800 ~12dB weaker than GSM900 (average Co-Loc) Lower Path Loss => Serve on GSM1800 GSM1800 Congestion => TRHO DL - UL Levels inconsistent => Manage Traffic with DL Level Only

Dublin: GSM900 MPD = ~170; GSM1800 MPD =~300 900->1800 HO: Best GSM900 Calls become Worst GSM1800 Calls

Summary


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Currently 66% Setup on GSM900, 33% on GSM1800 in Dualband AreaGSM1800: 4dB Bias over GSM900 e.g. -95dBm_1800 = -91dBm _900GSM1800: Access possible if > -98 dBm=> Calls setting up on poor GSM1800=> Immediate HO to GSM900 if RxLev_1800 < -95GSM900: 66% calls setup on 900=> Immediate HO to GSM1800 if RxLev_1800 >-84

STRATEGY:1. Increase GSM1800 RxLevAccessMin to Avoid Handback to GSM900 (OK)2. (a) Increase GSM1800 Bias to force more Call Setup on GSM1800 (???)2. (b) Or, Call Setup on GSM900 and Immediate HO to GSM1800 at -84 (???)

Idle Mode & Dualband


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Changes:

Idle Mode & Dualband (2)

STRATEGY:GSM1800: Hand In @ -84Hand Out @ -95 => Call Setup @ > -92 (on 1800)

4dB Bias & -98dBm Access => 33 % Call Setups on GSM1800 8dB Bias & -92dBm Access => 60 - 80 % Call Setups on GSM1800 ?


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Cell Reselect Hysterysis:Results showed too many LAC updates When Idle Serving 1800_RxLev dropped below -92dBm Reselection based on C2 1800 Cell on other LAC higher C2 than GSM900 on Same LAC Reselect the 1800 cell and do LAC update

REMEDY:=> Decrease Bias for GSM1800 cells=> Increase CellReselectHysterysis for GSM1800 cells

When Idle Serving 1800_RxLev dropped below -92dBm GSM900 on Same LAC selected more often 8 dB CRH for GSM1800 Cells ? ...6 dB CRH for GSM900 Cells ?


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GSM1800(-98 & 4 dB Bias)

GSM1800(-88 & 30 dB Bias)

GSM1800

(-92 & 8 dB Bias6 dB Hysterysis )

23 GSM1800 Cells in Cork

City Centre


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GSM1800GSM900

GSM900 &

GSM1800(46 Cells)


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GSM900 &

GSM1800(46 Cells)


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GPRS NEGATIVE IMPACT

More ReselectionsMore GPRS Interruptions

Total Throughput Increase(Retransmissions ?)

TRADE OFFCS Performace against PS Performance

S Idl M d M


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GSM1800 RxLevAccessMin: -98 change to -92=> Fewer calls setup on GSM1800=> Less Handback to GSM900

Currently, 33% Calls Setup on GSM1800 What is desired level?

All on GSM900 ? => Congestion and Handovers... 50% ? => Reselections ? => GPRS Impact All above -92dBm 1800 => More Reselections => GPRS Impact CellReselectHysterysis

Currently 4dB for GSM900 and GSM1800 cells 6dB Trialled for GSM1800 cells. Next trial 8dB for GSM1800, 6dB for GSM900 (Note: 6dB on Nortel)

Summary - Idle Mode Management

D di d M d & D lb d


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Traffic Reason HandoverNortel: If GSM1800 congested, can hand to GSM900 4dB weakerIf GSM900 congested, can hand to GSM1800 25dB weakerNokia: If GSM1800 congested, can hand to GSM900 4dB weakerIf GSM900 congested, can hand to GSM1800 4dBweaker

STRATEGY: If GSM1800 > -84dBm, then hand from GSM900 to GSM1800 No PBGT ho from GSM1800 to GSM900 If GSM1800 < -95dBm, then hand from GSM1800 to GSM900 If GSM1800 =< RxQual_4 => HO to GSM900 (orGSM1800 ... power budget)

GSM1800 may get congested => HO worst GSM1800 connections (=> room for Setup)Remove Traffic from GSM900 => reduce interferenceTraffic closest to cell fills up GSM1800 traffic furthest from cell served by GSM900

Dedicated Mode & Dualband

PBGT HO GSM900 GSM1800


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GSM900 - GSM1800:hoMargin: -15dB (were -7 to -22, most -15)GSM1800 - GSM900:hoMargin: 55dB (were mostly +15) (TRHO Margin =60)

Results for DNBSC12 and DNBSC18 (Changed Thursday 3rd Aug)

PBGT HO: GSM900 GSM1800

GSM900 GSM1800


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Increase in GSM1800 % TrafficNo Change in MPD

=> Traffic staying too long on GSM1800

Therefore:lRxQualULH& lRxQualDLHChange from 5 to 4 HO from GSM1800 Easier

GSM1800 - GSM900RxLevMinCell(n)Change from -95 to -100

Nokia (All BSCs)


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No a ( SCs)(Analysis for Cork-1, Cork-2, Waterford-2)26th June 2006

GSM900 &GSM1800

(3 BSCs)

GSM900 GSM1800


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GSM900 GSM1800

GSM900 & GSM1800


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Less Impact for Nokia than Nortel Less GSM1800

MPD decrease for GSM1800... UL Level Handover unnecessary => Disable GSM1800 - GSM900 RxLevMinCell(n)=>Change from -95 to -100

Handover Profiles


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Handover Profiles

(Nortel: UL Level HO and DL Level HO Disabled on Many BSCs already)

NORTEL

RxQual>HO Qual Threshold


=> 3.2% to 6.4% BER

I.e. BER>6.4%, then Quality HO

NOKIA

RxQual>=HO Qual Threshold


=> 3.2% to 6.4% BER

I.e. BER >=3.2%, then Quality HO

RxLevel Balance(UL Level HO Threshold: -110dBm)

RxQual Thresholds

HO Profile Comparison


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NOKIA 900 NOKIA 1800

NORTEL 900 NORTEL1800

DNBSC16 and DNBSC26


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Tue 25 July 06(UL Lev HO Disabled)

GSM900 GSM1800

Galway-1 and Galway-4


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Tues 18th July and Tues 25 July 06(UL Lev HO Disabled, DL Lev HO = -95 and -93)

GSM900 GSM1800


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GSM900:Swapped UL_Lev_HO for DL_Lev_HO

GSM1800:Less Lev HO after change.More PBGT => removed unnecessary UL _Lev_HO from GSM1800


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Nortel: Combining Dedicated Mode Optimisations

RxLevMinCell to GSM900 cell = -100 Therefore, increase HOMargin_Level to 2 RxQual Threshold for GSM1800 = 4

=> Easier to hand off GSM1800& Easier to Hand into GSM900

GSM900 and GSM1800


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GSM900 GSM1800

GSM900 GSM1800


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55dB PBGT for implemented some BSCs

GSM900 and GSM1800

Nokia:Enable Fast Ave PC


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Was disabled now EnabledDisabled => after PC command, level averaging is restarted=> Delay to HO

Trial: Waterford-1, -2, -3 Thurs 10th Aug: EnableFastAvePC = Enabled (all GSM900 and GSM1800) Mon 14th Aug: GSM900-GSM900 hoMarginPBGT 3 to 4

(No PC on GSM1800 => no hoMargin Change)

GSM900 & GSM1800 GSM1800


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Waterford-1, -2, 3GSM900 & GSM1800

Enable Fast Ave PC:Set to Enable For All Nokia:

900-900hoMarginPBGT = 4

Nokia:Diversity


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137 Cells with Diversity Disabled...?(Enabled Fri 18th Aug)

Again, 30 cells with Diversity disabled !

Summary - Dedicated Mode Management


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TRHO => Force Traffic on to GSM1800, reduces interference on GSM900 -15 hoMargin900-1800, Disable PBGT from GSM1800 to GSM900 Stay on GSM1800 until RxLev < -95; or RxQual > 4 (Nortel), >=5 (Nokia)

RxLevMinCell: 1800-900 = -100 => More Candidates for GSM1800 Rescue HO RxLevMinCell: 900-900 = -100 => More Candidates for GSM900 Rescue HO GSM900: hoMargin_Lev= 2 (because ofRxLevMinCellchange) Enable Fast Ave PC: enabled for Nokia runHandover: changed from 2 to 1 for Nortel GSM900-GSM900 hoMarginPBGT: changed from 3 to 4 due to above two changes Nokia Diversity: being disabled ?

hoMargin_Qual: Not investigated (for GSM900-GSM900 = -2) RxLev and RxQual averaging not investigated

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Dedicated Mode


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Dedicated Mode

Idle Mode

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