Multi Band Optimization
April 12, 2017 | Author: alqousi_muhieddine | Category: N/A
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Description
Multi-band Networks Optimization Which Multi-Band Configuration is suitable for Sudani?
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ideas to discuss 1. Introduction 2. Multi-Layer Configuration (HCS feature) 3. Concentric Cell Configuration (Co-BCCH feature) 4. Enhanced Dual band configuration (EDB feature)
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Introduction
• Principles of Dual band network. • Scenarios of implementing dual band networks. • Motives to optimize dual band network.
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Introduction
• In most of GSM networks world wide 900 Band was first used , then due to capacity bottlenecks on 900 band , 1800 band was added later. • 1800 coverage is weak ,very similar to 3G coverage because of close frequencies (little stronger). • Most of mobiles in market support both bands 900/1800. 4/6/15
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Introduction
• Dual band Networks can be used in multiple scenarios: 1. Multi-Layer scenario with priority to 1800
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1800
1800
1800
1800
900
900
900
900
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Introduction
2. equal priority with Traffic management feature 1800
900
1800
900
3. Co-BCCH (Concentric Cell) 900 TRX (BCCH) 900 Cells
900 TRX 1800 TRX 1800 TRX
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Introduction
• Triggers of Multi-band Optimization: 1. Traffic not distributed according to configured resources (TCH Congestion ) 2. Quality of one band is bad compared to the other band (DCR issue). 3. SDCCH congestion on one Band while no SDCCH traffic on the other band. 4. Too many drops during multiband handover (in concentric cell case)
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Multi-Layer Configuration (HCS feature)
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Feature Principles Pros and Cons Feature tuning Feature counters Practical Examples
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Multi-Layer Configuration (HCS feature)
• Feature Principles: •
900 Cells and 1800 Cells are separated into two Layers , where 1800 Cells have higher priority than 900 Cells.
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the MSs make calls on 1800 Cell as long as its coverage is acceptable, when coverage become very bad , the mobile goes to 900 Cell, so most of traffic is on 1800 Layer.
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In Idle mode most of MSs camps on 900 cells because of its excellent Rxlev compared to 1800 , to balance MSs in idle mode ,C2 parameters are tuned to keep part of MSs camping on 1800 Cells. Prepared by :
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Multi-Layer Configuration (HCS feature)
• Feature Principles: •
The priority settings don’t impact the GPRS/EDGE traffic , we can balance the GPRS EDGE traffic between the two bands using C2 reselection parameters.
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when MS initiate call from 900 Cell , it will perform inter-Layer HO to 1800 cell ,when the 1800 Cell coverage degrade the MS perform EDGE HO to 900 Cell.
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Multi-Layer Configuration (HCS feature)
1800 900 InterLayer HO
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EDGE HO
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Multi-Layer Configuration (HCS feature) 1800 InterLayer HO EDGE HO
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Multi-Layer Configuration (HCS feature) 1800 PBGT HO
PBGT HO
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Multi-Layer Configuration (HCS feature)
• Pros: •
• •
In case the operator has cleaner DCS band , this feature will be adequate because most of traffic will be on DCS, the DCR on network level will be better. Easier to control traffic than concentric cell , either by Tilting or by Parameter change. Can use different antennas , unlike concentric feature.
• Cons: • Each band is configured in separate cell , so more channels is needed for signaling • Too many cells in air interface create Prepared by : problems for optimization jobs like 4/6/15
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Inter-Layer Handover •
Handover initiated because of difference in Layer even if neighbor Rxlev is weaker. • Triggering conditions: • This type of handover is enabled , LEVHOEN=YES • One of the neighbors cells has higher priority than serving cells (higher priority ->parameter LAYER has lower value). • Target Cell Rxlev>=HOTHRES+ INTELEVHOHYST-64 • P/N criteria for Inter-Layer HO is satisfied. P parameter: LEVLAST=6 N parameter: LEVSTAT=4 • Load on 900 cells exceed the threshold : LAYHOLOADTH Prepared by : 4/6/15
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Inter-Layer Handover
900 1800
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1800 Cell Setting
900 Cell Setting
LAYER=2 HOTHRES=25 LEVHOEN=YES
LAYER=3 LAYHOLOADTH =0 LEVHOEN=YES
Per Neighbor INTELEVHOHYST =67 LEVLAST=6 LEVSTAT=4
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DL/UL Edge Handover • •
Edge Handover initiated because of bad coverage in either UL or DL Triggering conditions: • • • •
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This type of handover is activated FRINGEHOEN=YES. DL /UL Rxlev of 1800 cell is less than DLEDGETHRES/ULEDGETHRES. DL Rxlev of 900 cell is greater than (serving Dl Rxlev +INTERCELLHYST -64). P/N criteria of Edge Handover is satisfied: P parameter: EDGELAST1 N parameter: EDGESTAT1 Prepared by :
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DL/UL Edge Handover
900 1800 1800 Cell Setting FRINGEHOEN=YE S DLEDGETHRES=2 0 ULEDGETHRES=1 5 EDGELAST1=4 EDGESTAT1=6
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900 Cell Setting
Per neighbor INTERCELLHYST =67 EDGEADJLASTTIM E=4 EDGEADJSTATTIM E=6 Prepared by :
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C1/C2 Reselection parameters Tuning Parameter ID TO
Parameter Name Cell Reselect Temporary Offset
PT
Cell Reselect Penalty Time Cell Reselect Parameters Indication Cell Reselect Offset
PI CRO
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Actual Value Range 0~7 20~620, Step: 20 Seconds NO, YES 0~126, step: 2
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C1/C2 Reselection parameters Tuning The path loss criterion parameter C1 used for cell selection and reselection is defined by: C1 = ([Current Rxlev]- [Minimum Access RXLEV]Max([MS_TXPWR_MAX_CCH]- [Maximum RF output power of the MS],0)) for Cell Reselect Penalty Time 31: C2 = C1 + [Cell Reselect Offset]- [Cell Reselect Temporary Offset]* H([Cell Reselect Penalty Time] - T) for Cell Reselect Penalty Time = 31 C2 = C1 – [Cell Reselect Offset]
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C1/C2 Reselection parameters Tuning 900 Cell Parameters
1800 Cell Parameters
Minimum Access RXLEV=12 Cell Reselect Penalty Time=0 Cell Reselect Offset=0 Cell Reselect Temporary Offset=0
Minimum Access RXLEV=8 Cell Reselect Penalty Time=25 Cell Reselect Offset=0 Cell Reselect Temporary Offset=5
Before Penalty Timer expiration MS#1 MS#2 Cell Cell Name C1 C2 Name C1 C2 1550-1 13 13 1550-1 13 13 5000-5 21 11 5000-5 21 11 After Penalty Timer expiration MS#1 MS#2 Cell Cell Name C1 C2 Name C1 C2 1550-1 13 13 1550-1 13 13 5000-5 21 21 5000-5 21 11
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1550-1 (900 Cell) Average Rxlev for both MSs is -85 dBm MS1 MS2
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5000-5 (1800 Cell) 21
C1/C2 Reselection parameters Tuning 1800 Cell Parameters
900 Cell Parameters
Minimum Access RXLEV=8 Cell Reselect Penalty Time=0 Cell Reselect Offset=0 Cell Reselect Temporary Offset=0
Minimum Access RXLEV=12 Cell Reselect Penalty Time=31 Cell Reselect Offset=4 Cell Reselect Temporary Offset=0
The above settings will make C2 of 1800 Cell preferred by 12 dB on 900 Cell
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Important counters for MultiLayer Optimization Measurement function BSC Measurement
Measurement sub-function
Counter Name
Call Measurement per BSC
ZTCA3351H:Number of Calls Originated or Terminated by MSs Supporting DCS1800 Band per BSC S335:Mean Uplink Receiving Level during Edge Handover Initiation S336:Mean Downlink Receiving Level during Edge Handover Initiation H3101Y:Number of Outgoing Internal Inter-Cell Handover Requests (Directed Retry) (900/850/810-1800/1900) H3101Z:Number of Outgoing Internal Inter-Cell Handover Requests (Directed Retry) (1800/1900-900/850/810) H372C:Failed Outgoing Inter-Cell Handovers (Uplink Strength) H372D:Failed Outgoing Inter-Cell Handovers (Downlink Strength) H374C:Outgoing Inter-Cell Handover Requests (Uplink Strength) H374D:Outgoing Inter-Cell Handover Requests (Downlink Strength) H373C:Successful Outgoing Inter-Cell Handovers (Uplink Strength) H373D:Successful Outgoing Inter-Cell Handovers (Downlink Strength)
Call Measurement MR Measurement upon Handover per Cell Call Measurement MR Measurement upon Handover per Cell Call Measurement Outgoing Internal Inter-Cell Handover Measurement per Cell Call Measurement Outgoing Internal Inter-Cell Handover Measurement per Cell Call Measurement Call Measurement Call Measurement Call Measurement Call Measurement Call Measurement
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GSM Cell to GSM Cell Outgoing Handover Measurement GSM Cell to GSM Cell Outgoing Handover Measurement GSM Cell to GSM Cell Outgoing Handover Measurement GSM Cell to GSM Cell Outgoing Handover Measurement GSM Cell to GSM Cell Outgoing Handover Measurement GSM Cell to GSM Cell Outgoing Handover Measurement
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Practical case #1 900 Cell 1800 Cell Parameters
Parameters
DLEDGETHRES=2 0 ULEDGETHRES=1 5 INTERCELLHYST =67 EDGELAST1=4 EDGESTAT1=6 HOTHRES=25 INTELEVHOHYST= 67 1800 KPI BH LEVLAST=6 Status LEVSTAT=4
DLEDGETHRES=2 5 ULEDGETHRES=2 0 INTERCELLHYST =67 EDGELAST1=4 EDGESTAT1=6 HOTHRES=35 INTELEVHOHYST= 67 900 KPI BH Status LEVLAST=6 LEVSTAT=4 No Congestion TCH Utilization95% TRX Expansion is not Possible
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Inter Layer HO Formula: Target Cell Rxlev>=HOTHRES+ INTELEVHOHYST-64 EDGE HO Formula: Serving Cell Rxlev>=DLEDGETHRES/ULEDGETHRES
1800
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Practical Case # 2 900 Cell 1800 Cell Parameters
Parameters
DLEDGETHRES=2 0 ULEDGETHRES=1 5 INTERCELLHYST =67 EDGELAST1=4 EDGESTAT1=6 HOTHRES=35 INTELEVHOHYST= 1800 KPI BH 67 Status LEVLAST=6 LEVSTAT=4 No Congestion TCH Utilization95% TRX Expansion is not Possible
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Inter Layer HO Formula: Target Cell Rxlev>=HOTHRES+ INTELEVHOHYST-64 EDGE HO Formula: Serving Cell Rxlev>=DLEDGETHRES/ULEDGETHRES
1800
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Concentric Cell Configuration (CoBCCH)
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Feature Principle Pros and Cons Feature tuning Feature counters Practical Exercise
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Concentric Cell Feature EGSM900 Cell BCCH 900 TRXs
TRX#2 TRX#3 TRX#4
1800 TRXs
TRX#2 TRX#3 TRX#4
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Concentric Cell Configuration (CoBCCH) •
Feature Principles: 1. There is no 1800 Cells in the network, 1800 TRXs are added as additional TRXs to 900 Cells. 2. During the drive test the mobile can see only 900 cells 3. All the signaling channels and GPRS/EDGE channels are in 900 TRXs only. 4. The mobile initiate the call from 900 SDCCH , then the BSC will decide whether to give it 900 TCH or 1800 TCH according to Rxlev and distance of the mobile. 5. When the mobile making call on 900 TCH , it cannot see the Rxlev of 1800 TRXs. 6. If the mobile goes closer to the cell while using 900 TCH , it will perform intra-Cell handover from 900 TRX to 1800 TRX based Preparedon by : specific threshold
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Concentric Cell Configuration (CoBCCH) •
Feature Principles: 7. 1800 TRXs use 1800 MA list frequencies and 900 TRXs use 900 MA list frequencies (two MA lists in one Cell) 8. Since all TRXs are configured under one cell , the antennas used for 900 and 1800 TRXs should be the same antenna . 9. Parameters can be tuned to push traffic from 1800 TRXs to 900 TRXs or the opposite (different parameters from multi-Layer). 10. The group of TRXs that belong to same band are called SubCell so each cell has two SubCells :overlaid and underlaid subcells
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Concentric Cell Configuration (CoBCCH) •
Pros: 1. Better capacity Efficiency (traffic capacity of 6 TRXs in one cell is larger than traffic of 3+3 TRXs in two separate Cells). 2. Save BCCH and SDCCH timeslots since there is only one cell used. 3. Easier to optimize the neighbors and change BCCH frequencies (not too many neighbors). 4. Less Interference on 1800 band because there is no BCCH carrier any more.
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Concentric Cell Configuration (CoBCCH) •
Cons: 1. Higher DCR than multi-Layer configuration because the mobile cannot see 1800 Rxlev while served by 900 TRXs, so drop occur during intra-Cell handover. 2. Less efficient in distributing traffic so more probability of TCH congestion on one of the SubCells 3. Harder to Optimize from Parameters tuning point of view. 4. fixed GPRS and EDGE TSs are on 900 TRXs , this band will be more interfered than 1800 Band. 5. Requires License of Concentric cell and license of Co-BCCH Prepared by :
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Concentric Cell Handover Scenarios Intra Cell HO OL to UL
OL SubCell
UL SubCell
UL SubCell
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OL SubCell
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Intra Cell HO UL to OL
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Concentric Cell Parameters MO
Parameter ID
Parameter Name
GCELL
ENIUO Enhanced Concentric Allowed TCHTRICBUSYOVERLAYT Tch Traffic Busy Overlay GCELLCHMGAD HR Threshold TCHTRIBUSYUNDERLAYT Tch Traffic Busy Underlay GCELLCHMGAD HR Threshold GCELLHOIUO ULTOOLHOALLOW UL to OL HO Allowed GCELLHOIUO OLTOULHOALLOW OL to UL HO Allowed GCELLHOIUO RECLEVUOHOALLOW RX_LEV for UO HO Allowed GCELLHOIUO RECQUALUOHOALLOW RX_QUAL for UO HO Allowed GCELLHOIUO TAFORUOHOALLOW TA for UO HO Allowed GCELLHOIUO RECLEVTHRES RX_LEV Threshold GCELLHOIUO RECLEVHYST RX_LEV Hysteresis GCELLHOIUO RECQUALTH RX_QUAL Threshold GCELLHOBASIC ATCBHOEN Concentric Circles ATCB HO Allowed Distance Between Boundaries of GCELLHOEDBPARA ATCBTHRED Subcells GCELLHOEDBPARA Distance Hysteresis Between ATCBHYST Boundaries
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Recommend ed Value ON 70 60 YES YES YES NO NO 30 5 60 YES 10 2
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Usually tuned Parameters MO
Parameter ID
GCELLHOIUO GCELLHOIUO GCELLHOIUO GCELLHOIUO GCELLHOIUO
TATHRES TAHYST IUOHOSTATIME IUOHODURATIME OPTILAYER
Parameter Name
TA Threshold TA Hysteresis UO HO Watch Time UO HO Valid Time Assign Optimum Layer Assign-optimum-level GCELLHOIUO OPTILEVTHRES Threshold TA Threshold of Assignment GCELLHOIUO OPTITATHRES Pref GCELLHOIUO HOALGOPERMLAY Pref. Subcell in HO of Intra-BSC Incoming-to-BSC HO Optimum GCELLHOIUO ACCESSOPTILAY Layer OtoU HO Received Level GCELLHOIUO OTOURECEIVETH Threshold UtoO HO Received Level GCELLHOIUO UTOORECTH Threshold GCELLHOIUO UTOOTRAFHOALLOW UtoO Traffic HO Allowed PS OtoU HO Receive Level GCELLHOIUO PSOTOURECEIVETHRSH Threshold PS UtoO HO Receive Level GCELLHOIUO PSUTOORECEIVETHRSH Threshold TA Based PS UO Assignment GCELLHOIUO PSTAFORUOHOALLOW Allowed GTRXIUO IUO Concentric Attribute 4/6/15
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Recommended Value 63 0 10 8 SysOpt 35 63 SysOpt Usubcell 20 35 NO 25 35 NO NONE 34
Channel Assignment •
In case the parameter OPTILAYER is set to SysOpt 1. If SDCCH MRs are available ,the Layer chosen is determined by : Receive level > RECLEVTHRES + RECLEVHYST (not enhanced) Receive level > UTOORECTH (enhanced concentric cell) Where Receive level is the average of Dl Rxlev extracted from SDCCH measurement reports sent by MS. 2. If SDCCH MRs are not available ,the Layer chosen is determined by : Receive level > OPTILEVTHRES Where Receive level is the average of UL Rxlev MRs collected by BTS.
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In case the parameter OPTILAYER is set to UL or OL preferred: 1. If the UL is preferred the mobile will be assigned in UL , if 4/6/15
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HO UL2OL and OL2UL •
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UL to OL: •
If the enhanced Concentric Cell is not enabled (ENIUO=OFF) Receive level > RECLEVTHRES + RECLEVHYST
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If the enhanced Concentric Cell is enabled (ENIUO=ON) Receive level > UTOORECTH Rxlev(Serving)– Rxlev(Neigh)> ATCBTHRED + ATCBHYST
OL to UL: •
If the enhanced Concentric Cell is not enabled (ENIUO=OFF) Receive level < RECLEVTHRES - RECLEVHYST
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If the enhanced Concentric Cell is enabled (ENIUO=ON) Receive level < OTOURECTH Rxlev(Serving)– Rxlev(Neigh)< ATCBTHRED + ATCBHYST 36
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Overlaid area calculation OL Area defined by the following conditions: Receive level > RECLEVTHRES + RECLEVHYST TA < TATHRES –TAHYST XOR RxQual
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