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Module 1Multiband Multilayer Network Architecture
3JK11166AAAAWBZZA Issue 01
Section 1Multiband & Multilayer
Optimization
EVOLIUM Base Station SubsystemMultiband and Multilayer GSM network radio optimization - B10
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Module Objectives
Upon completion of this module, you should be able to:
Define relevant architectures for multilayer networks design
Define relevant architectures for multiband networks design
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Module Objectives [cont.]
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Table of Contents
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Table of Contents [cont.]
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1 Concepts and Strategies
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1 Concepts and Strategies
Introduction to Multilayer Networks
Multiband/Multilayer network: a powerful solution for:
Network capacity enhancement
extra capacity provided by new cells / new TRXs
specific radio algorithms send MSs to these new cells
Coverage increase
when introducing microcells (better indoor penetration, even for outdoor microcells)
While keeping a good QoS
Confined coverage for microcells easier frequency planning
New frequency band less tigh frequency planning
Less congestion
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1 Concepts and Strategies
Support of Multilayer and Multiband Features
Alcatel-Lucent is providing multilayer solutions:
Mini, microcells and Indoor layer
smart speed discrimination
external Directed Retry
Alcatel-Lucent is providing multiband solution
Multiband BSC
Multiband cells
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1 Concepts and Strategies
Network Strategy (Multilayer)
Multilayer networks can be introduced as continuous layer or hotspots, for:
Capacity increase
Coverage increase
Indoor solution
All types of mobiles can use both layers
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1 Concepts and Strategies
Network Strategy (Multiband)
The new band introduction can be done
In a mono-layer network
In the same layer
In a new layer
In a Multilayer network
In the upper layer
In the lower layer
As part of an existing cell design: multiband cells
Depending on the architecture chosen:
Different parameters settings
Different ways of QoS and traffic monitoring
Each architecture has drawbacks and advantages
The main issue is to achieve an efficient traffic sharing between the 2 bands
Risk of congestion on one band and low traffic on the other band
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2 Cellular Network Architecture
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2 Cellular Network Architecture
Cell Environment
Conventional
Single cell
Concentric cell
Extended cell
Multiband cell
Hierarchical: introducing Upper and Lower cell layers
Indoor cell
Micro cell
Mini cell
Umbrella cell
Multiband: Classical and Preferred frequency bands
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2 Cellular Network Architecture
Cell Profile
One unique combination of the five parameters
CELL_DIMENSION_TYPE: macro, micro
CELL _LAYER_ TYPE : single, upper, lower, indoor
CELL _PARTITION_ TYPE : normal, concentric
CELL _RANGE: normal, extended inner, extended outer
FREQUENCY_RANGE : PGSM(GSM900); DCS1800; EGSM; DCS1900; PGSM-DCS1800; EGSM-DCS1800 and GSM 850
based on BCCH frequency
A multiband cell is defined by:
FREQUENCY_RANGE = PGSM-DCS1800 or EGSM-DCS1800
CELL _PARTITION_ TYPE of the cell is then forced to concentric
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Exercise
Link the logical cell types (as defined in the OMC-R) with the cell profile parameters.
Indoor
Micro
Mini
Umbrella
Cell Layer TypeCell Dimension
TypeCell Type
5 minutes
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2 Cellular Network Architecture
Mono-Band Cell Profiles
DCS1800 or DCS1900DCSNormalNormalIndoorMicroDCS indoor micro cell
PGSM or EGSMGSMNormalNormalIndoorMicroGSM indoor micro cell
DCS1800 or DCS1900DCSNormalConcentricUpperMacroDCS concentric umbrella
PGSM or EGSMGSMNormalConcentricUpperMacroGSM concentric umbrella
DCS1800 or DCS1900DCSNormalConcentricSingleMacroDCS concentric cell
PGSM or EGSMGSMNormalConcentricSingleMacroGSM concentric cell
DCS1800 or DCS1900DCSExtended-outerNormalSingleMacroDCS extended outer cell
PGSM or EGSMGSMExtended-outerNormalSingleMacroGSM extended outer cell
DCS1800 or DCS1900DCSExtended-innerNormalSingleMacroDCS extended inner cell
PGSM or EGSMGSMExtended-innerNormalSingleMacroGSM extended inner cell
DCS1800 or DCS1900DCSNormalNormalUpperMacroDCS umbrella cell
PGSM or EGSMGSMNormalNormalUpperMacroGSM umbrella cell
DCS1800 or DCS1900DCSNormalNormalLowerMacroDCS mini cell
PGSM or EGSMGSMNormalNormalLowerMacroGSM mini cell
DCS1800 or DCS1900DCSNormalNormalLowerMicroDCS micro cell
PGSM or EGSMGSMNormalNormalLowerMicroGSM micro cell
DCS1800 or DCS1900DCSNormalNormalSingleMacroDCS single cell
PGSM or EGSMGSMNormalNormalSingleMacroGSM single cell
Frequency rangeCell band
type
Cell
range
Cell partition
type
Cell layer
type
Cell dimension
type
Parameters
Cell Profile
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2 Cellular Network Architecture
Multiband Cell Profiles
PGSM-DCS1800 or EGSM-DCS1800
DCSNormalConcentricIndoorMicroDCS multiband indoor micro cell
PGSM-DCS1800 or EGSM-DCS1800
GSMNormalConcentricIndoorMicroGSM multiband indoor micro cell
PGSM-DCS1800 or EGSM-DCS1800
DCSNormalConcentricUpperMacroDCS multiband umbrella cell
PGSM-DCS1800 or EGSM-DCS1800
GSMNormalConcentricUpperMacroGSM multiband umbrella cell
PGSM-DCS1800 or EGSM-DCS1800
DCSNormalConcentricLowerMacroDCS multiband mini cell
PGSM-DCS1800 or EGSM-DCS1800
GSMNormalConcentricLowerMacroGSM multiband mini cell
PGSM-DCS1800 or EGSM-DCS1800
DCSNormalConcentricLowerMicroDCS multiband micro cell
PGSM-DCS1800 or EGSM-DCS1800
GSMNormalConcentricLowerMicroGSM multiband micro cell
PGSM-DCS1800 or EGSM-DCS1800
DCSNormalConcentricSingleMacroDCS multiband single cell
PGSM-DCS1800 or EGSM-DCS1800
GSMNormalConcentricSingleMacroGSM multiband single cell
Frequency rangeCell band typeCell rangeCell partition typeCell layer typeCell dimension typeParameters
Cell Profile
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2 Cellular Network Architecture
Cell Profiles: Example
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3 Choosing a Relevant Architecture
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3 Choosing a Relevant Architecture
Concept
Multilayer concept: 3 available layer types
All these cells can be or not operating in the same band and defined as concentric cells
mini
umbrella
micro
indoor
micro micro
umbrella
micro
indoor
single
mini
umbrellaUPPER
SINGLE
LOWER
INDOOR
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3 Choosing a Relevant Architecture
Microcell Classes
Microcells configuration will depend on their position in the lower layer
Microcell classes are introduced to deal with typical parameters settings in each of these cases
Indoor Microcell
Border Microcell
Inner MicrocellHotspot Microcell
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3 Choosing a Relevant Architecture
Mono-layer architecture
In a mono-layer network, a new band may be introduced:
In the same layer
Macro 900 (single)
Macro 1800 (single)
900-1800 interworking managed by priority set by the operator
In a separate layer
Macro 900 (umbrella)
Macro 1800 = mini
900-1800 interworking driven by a dual layer architecture (easier to introduce but less flexible)
900 900 1800 1800
900 900
mini1800 mini1800
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3 Choosing a Relevant Architecture
Multilayer architecture (1/3)
In a multilayer network, a new band may be introduced:
In the upper layer
Macro 900 (umbrella)
Macro 1800 (umbrella)
Micro 900
In the lower layer
Macro 900 (umbrella)
Macro 1800 = mini
Micro 900
900 900 1800 1800
900 900
mini1800
900 900
900 900
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3 Choosing a Relevant Architecture
Multilayer architecture (2/3)
Higher Priority to 1800 macrocell
GSM 900 macrocell as a pool of traffic resources when the preferred cell is congested
2
1
Initial access
3
Traffic based handover2
1
Directed retryEmergency Handover
900
900
1800
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3 Choosing a Relevant Architecture
Multilayer architecture (3/3)
Higher Priority to 900 microcell
GSM 900 & 1800 macrocell as a pool of traffic resources when the preferred cell is congested
1
2
Initial access
3
Traffic based handover1
2
Directed retryEmergency Handover
900
900
1800
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3 Choosing a Relevant Architecture
Multiband cell solution
Also called single BCCH
Based on the concentric cell feature
New band is introduced in existing cells
In the INNER zone (contains only TCH)
The OUTER zone contains BCCH, SDCCH and TCH
9001800 9001800
900
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4 Requirements
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4 Requirements
Software & Hardware Requirements
Multilayer architecture
Hardware: All generations
Note : Any BTS can be declared with the cell type = MICRO
Software
External Directed Retry in B6.2 ( cells and umbrella cells from different BSC possible)
INDOOR layer
Multiband architecture
Hardware :
The BSC can manage TRXs from different bands
The Evolium BTS can support TRXs from different bands within one cell
1 cell can be split over 2 BTS's (TRX 900 and TRX 1800 in different BTS's possible)
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4 Requirements
Cell split for the multiband cells
1 cell can be split over 2 BTS HW
As soon as these BTSs share the same clock
Master / Slave configuration needed
G2 & G3 BTSs can be mixed
Example of site configurations:
G2 BTS 3x4 TRX 900 + 1 Evolium BTS 3x4 TRX 1800
3 multiband cells 4(900)+4(1800) TRX
Evolium BTS 6+6 TRX 900 + Evolium BTS 6 TRX 900+ Evolium BTS 3*4 TRX 1800
3 multiband cells 6(900)+4(1800) TRX
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Exercise
Give the major advantages and drawbacks of the multiband cells solution
15 minutes
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Self-Assessment on the Objectives
Please be reminded to fill in the formSelf-Assessment on the Objectivesfor this module
The form can be found in the first partof this course documentation
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End of ModuleMultiband Multilayer Network Architecture
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Module 2Algorithms and Associated Parameters
3JK11167AAAAWBZZA Issue 01
Section 1Multiband & Multilayer
Optimization
EVOLIUM Base Station SubsystemMultiband and Multilayer GSM network radio optimization - B10
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Module Objectives
Upon completion of this module, you should be able to:
Describe algorithms dedicated to multilayer and multiband networks management
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Module Objectives [cont.]
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Table of Contents
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Table of Contents [cont.]
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1 Introduction
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1 Introduction
Justification
Multiband/Multilayer brings new features and algorithms :
Designing, managing and monitoring complex networks is more difficult
A relevant choice of architecture and parameters settings will precede the introduction of a new layer in the existing network
To be sure to implement correctly the best strategy for your network, knowledge of all algorithms and parameters is mandatory.
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1 Introduction
Typing Conventions
In all this document
SYSTEM PARAMETERS (can be set at the OMC-R level) will always be written in BLUE BOLD FONT
VARIABLES (averages, internal system variables, etc.) will be typed in NORMAL FONT
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2 Neighboring cells list
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2 Neighboring cells list
Purpose
Neighboring cells list is sent to the MS regularly and contains all BCCH frequencies of neighbor cells to be monitored by the MS
The MS measures them regularly in order to :
Perform cell selection & reselection (in idle mode)
Report 6 BCCH RxLev to the BSS for handovers (in dedicated mode)
7987982020
4545
800800
805805
22
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2 Neighboring cells list
Idle Mode
2 possibilities, the MS camps on either :
A cell with a BCCH on a DCS 1800 frequency
Or a cell with a BCCH on a GSM 900 frequency
805805BCCH 1800SI 2 and 2bis : 1800 neighboring cellsSI 2ter : 900 neighboring cells
2020BCCH 900SI 2: 900 neighboring cellsSI 2ter (& 2bis): 1800 neighboring cells
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2 Neighboring cells list
Dedicated Mode
2 possibilities, the call is performed on either :
A cell with a BCCH on a DCS 1800 frequency
Or a cell with a BCCH on a GSM 900 frequency
805805SACCHSI 5 and 5bis: 1800 neighboring cellsSI 5ter: 900 neighboring cells
2020SACCHSI 5: 900 neighboring cellsSI 5ter (& 5bis): 1800 neighboring cells
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2 Neighboring cells list
Multiband configuration
Which ever is the band of the current cell, the MS can receive BCCH list that belongs to the other band only with :
SI-2ter
SI-5ter
To enable/disable this SI messages on BCCH and SACCH
EN_INTERBAND_NEIGH = enable (1)
EN_INTERBAND_NEIGH = disable (0)
Description : BSC parameter that enables / disables the multiband operation by filtering the sending of SYSTEM INFORMATION TYPE 2ter/5ter.
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2 Neighboring cells list
Cell Monitoring
In dedicated mode, a MS can only report 6 measurements :
Standard behavior in a mono-band network : MS reports the 6 strongest cells
Problem : in a multiband network, 1800 cells provides less signal strength and might not be included in the 6 strongest neighbors !
805805
MEAS REPORT
N1 : (BSIC, RXLEV)
N2 : (BSIC, RXLEV)
N3 : (BSIC, RXLEV)
N4 : (BSIC, RXLEV)
N5 : (BSIC, RXLEV)
N6 : (BSIC, RXLEV)
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2 Neighboring cells list
Cell Monitoring [cont.]
Reported neighbors from each band can be forced thanks to the cell parameter :
MULTIBAND_REPORTING
4 possible values
0: 6 strongest cells irrespective of the frequency band
1: 1 strongest cell (non-serving cell frequency band) + 5 strongest cells(serving cell frequency band)
2: 2 strongest cells (non-serving cell frequency band) + 4 strongest cells(serving cell frequency band)
3: 3 strongest cells (non-serving cell frequency band) + 3 strongest cells(serving cell frequency band)
Default value:
0 for mono-band network
3 for multiband network
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2 Neighboring cells list
Cell Monitoring Optimization
MULTIBAND_REPORTING has to be tuned carefully in multiband network, since no handover can be done to a cell which is not reported
The parameter value is depending on network strategy and may be tuned differently in each band
Example: give priority to 1800 cells
In 900 layer cells
MULTIBAND_REPORTING = 1 is most of the time sufficient to make a handover towards the preferred band
In 1800 layer cells
MULTIBAND_REPORTING = 3 : 1800 neighboring cells have to be reported to keep the MS in the same band when possible, but 900 cells should be reliably reported as they are rescue cells.
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2 Neighboring cells list
Number of neighboring cells
Neighboring cells list limited to 32 BCCH's in OMC-R :
Limit easily reached in a network with 3 or 4 layers, and 2 bands
A special care must be taken when defining the list of neighboring cells
The multiband cells solution dramatically reduces this problem when introducing new frequency band
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3 Idle Mode Selection and Reselection
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3 Idle Mode Selection and Reselection
Strategy
Adding a new band/layer is a powerful way of increasing network capacity if the MS can be sent to the preferred cell
In dedicated mode: see next sections
But also in idle mode, so that the call is established directly in the preferred cell
Really increase capacity
Maintain high QoS level, without creating extra HO
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3 Idle Mode Selection and Reselection
Selection and Reselection Principle
At startup (IMSI Attach), the MS is selecting cell with
Defined priorities with CELL_BAR_QUALIFY
Best C1 amongst highest priority cells (using CBQ)
Once camped on one cell (in idle mode)
The MS can decide to reselect another one if:
C1 criterion < 0
The MS cannot decode downlink signalling blocks of Paging Channel
The current cell is becoming forbidden (e.g. barred)
A random access attempt is still unsuccessful after "Max retrans" repetitions
MS detects the network has failed authentication check
There is a better cell, regarding C2 criterion
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3 Idle Mode Selection and Reselection
Cell Selection with CBQ
Cell selection, use of CELL_BAR_QUALIFY: Set on a per cell basis
Broadcast on the BCCH
2 possible values:
0 = normal priority (default value)
1 = lower priority
The MS selects the suitable (C1 > 0) cell with the highest C1 belonging to the list of highest priority
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3 Idle Mode Selection and Reselection
Cell Selection with CBQ [cont.]
Example: highest priority set on microcell
The MS will select the microcell (if available, C1>0), whatever the level of the macrocell
2525 microcellCELL_BAR_QUALIFY = 0
2020
macrocell
CELL_BAR_QUALIFY = 1
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3 Idle Mode Selection and Reselection
Cell Selection with CBQ [cont.]
WARNING: usage of CELL_BAR_QUALIFY: interacts with CELL_BAR_ACCESS
A cell with low priority (CELL_BAR_QUALIFY = 1) cannot be barred
Some MSs will be able to access it, whatever the value of CELL_BAR_ACCESS
normal (see note 1)low11
normal (see note 1)low01
barredbarred10
normalnormal00
Status for cell reselectionCell selection priorityCELL_BAR ACCESS
CELL_BAR QUALIFY
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3 Idle Mode Selection and Reselection
C1 Criterion
C1
ensures that, if a call was attempted, it would be done with a sufficient downlink and uplink received level
based on 2 parameters, broadcast on the BCCH
RXLEV_ACCESS_MIN [dBm] Minimum level to access the cell
Default value (for Evolium): -103 dBm
MS_TXPWR_MAX_CCH [dBm] Maximum level for MS emitting
Default value: 33 dBm
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3 Idle Mode Selection and Reselection
C1 Criterion [cont.]
C1
evaluated every 5 s (minimum)
C1 = A - MAX(0,B) > 0
A = RxLev - RXLEV_ACCESS_MIN assess that the MS received level is sufficient
B = MS_TXPWR_MAX_CCH - P P maximum power of MS
assess that the BTS received level will be sufficient
if MS_TXPWR_MAX_CCH < P
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3 Idle Mode Selection and Reselection
C2 Criterion
C2
If CELL_RESELECT_PARAM_IND= not present
C2=C1
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3 Idle Mode Selection and Reselection
C2 Criterion [cont.]
C2
If CELL_RESELECT_PARAM_IND= present
And if PENALTY_TIME Infinity ( 640s)
Cell is arriving in neighbor list :
C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY_OFFSET (T)
Cell has been in neighbor list for more than PENALTY_TIME
C2 = C1 + CELL_RESELECT_OFFSET
CELL_RESELECT_OFFSET used to favor a cell among other (e.g. micro-cell vs. umbrella, once T > PENALTY_TIME)
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3 Idle Mode Selection and Reselection
C2 Criterion [cont.]
C2
If CELL_RESELECT_PARAM_IND= present
And if PENALTY_TIME = Infinity (= 640s)
C2 = C1 - CELL_RESELECT_OFFSET
CELL_RESELECT_OFFSET used to handicap some cells among others
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3 Idle Mode Selection and Reselection
C2 Criterion [cont.]
Case of "better cell" reselection
The MS will select the neighbor cell if :
Cells in same Location Area
C2neighbor > C2current
Cells in different Location Area
C2neighbor > C2current + CELL_RESELECT_HYSTERESIS
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3 Idle Mode Selection and Reselection
C2 Parameters
CELL_RESELECT_PARAM_IND C2 parameters are broadcast if = ENABLE (default)
otherwise C2 = C1
PENALTY_TIME
From 20s to 620s, in "20s" increment step
Default value = 20s
640s : infinite penalty
CELL_RESELECT_OFFSET
From 0 dB to 126 dB, in "2dB" increment step
Default value = 0dB
TEMPORARY_OFFSET From 0 dB to 60 dB, in "10dB" increment step (+ Infinity)
Default value = 0dB
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3 Idle Mode Selection and Reselection
Applications
MINIMINI UMBUMB
MS in Idle Mode
RxLev(Mini) = -70dBm C2(Mini) =
RxLev(Umb) = -65dBm C2(Umb) =
=> Which cell is favored in Idle Mode ?
MINI 900CELL_RESELECT_OFFSET = 6 dBTEMPORARY_OFFSET = 0 dBPENALTY_TIME = 0 (20 s)
UMBRELLA 900CELL_RESELECT_OFFSET = 0 dBTEMPORARY_OFFSET = 0 dBPENALTY_TIME = 0 (20 s)
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3 Idle Mode Selection and Reselection
Applications [cont.]
MINIMINI UMBUMB
MS in Idle Mode
RxLev(M900) = -70dBm C2(M900) =
RxLev(M1800) = -72dBm C2(M1800) =
=> Which cell is favored in Idle Mode ?
MINI 1800CELL_RESELECT_OFFSET = 4 dBTEMPORARY_OFFSET = 0 dBPENALTY_TIME = 0 (20 s)
MINI 900CELL_RESELECT_OFFSET = 0 dBTEMPORARY_OFFSET = 0 dBPENALTY_TIME = 0 (20 s)
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3 Idle Mode Selection and Reselection
CRO Tuning
In a multiband network :
Differences in TRX output power
TRX 1800 MP (TRADE) = 45.4 dBm
TRX 900 MP (TRAGE) = 46.5 dBm
Differences in path loss
On a same path :
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3 Idle Mode Selection and Reselection
CRO Tuning [cont.]
Therefore, a 1800 cell will provide less coverage than a 900 cell
Delta = 8~10dB
Less traffic is carried by 1800 cells (more capacity available)
Additionally, the 1800 frequency planning is usually cleaner than the 900 one.
Even at low RxLev, a 1800 cell might provide a coverage with good quality and good capacity
For this reason, CRO is used to advantage 1800 cells over 900 cells.
Within a same layer : CRO(1800) = CRO(900) + 2~8dB
Among different layers : CRO(1800) = CRO(900) + 4~12dB
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3 Idle Mode Selection and Reselection
Exercise
Is there a way to keep fast-moving mobiles in the upper layer ?
2 minutes
TEMPORARY_OFFSET(lower/indoor) = Infinity
PENALTY_TIME(lower/indoor) = 20s
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4 Call Setup
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4 Call Setup
Principles
Call setup is made on the cell (re)selected in idle mode
Idle mode parameters favour the preferred cells
Lower layers
Preferred band
What is the risk?
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4 Call Setup
Congestion in the Preferred Cell
The risk is to have congestion in the preferred cell!
Classical band / upper cells are unloaded
as all MSs are sent to new cells in idle mode
This phenomenon is further amplified by handovers behavior
Multiband/multilayer algorithms are based on CAPTURE mechanisms
Send the MS in the preferred cell as soon as it is OK
Without comparing serving and preferred cells
to reach the maximum capacity increase
(See handover parts for details)
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4 Call Setup
Algorithms Principles
New capacity
Trafficincrease
Old capacity
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4 Call Setup
Algorithms Principles (cont.)
New capacity
Trafficincrease
Old capacity
Water Valve with filter:
Dual layer algorithms
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4 Call Setup
Algorithms Principles (cont.)
New capacity
Trafficincrease
Old capacity
Water Pump:
Forced
Directed Retry and
Fast Traffic
handover
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4 Call Setup
Directed Retry Principles
A Directed Retry:
SDCCH to TCH intercell handover
Triggered during a call setup procedure
MSServingCell BSC
MSC
Assignment Request
SDCCH Assignment PhaseSDCCH Assignment Phase
SDCCH PhaseSDCCH Phase(SDCCH)
T11
ChannelActivation
HandoverHandover
(TCH)
TargetCell
HO Command
ack
HO Access
HO CompleteAssignment Complete
Serving cell is congested, waiting to find a neighbor cell
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4 Call Setup
Directed Retry Principles [cont.]
Internal and External Directed Retries are possible
Handover detection based on standard intercell HO algorithms:
- Too low level- Too bad quality- Power Budget / Traffic HO- Capture (14, 21, 24)- etc. (except Fast Traffic HO)
Handover detection based on a specific algorithm (Cause 20).
Candidate cell evaluation based on specific criteria.
Normal Directed RetryNormal Directed Retry Forced Directed RetryForced Directed Retry
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4 Call Setup
Normal Directed Retry
Set on a per cell basis with parameter EN_DR
EN_DR = enable (DR execution is enabled in the cell)
EN_DR = disable (DR execution is disabled in the cell)
Executed only if no TCH available in serving cell and standard intercell HO detected
Except Intracell HO causes 10, 11 and 13 (concentric cells) and causes 15 and 16 (interference HO)
Except Cause 28 (Fast Traffic HO)
The target cell is chosen by the BSC based on the HO detected
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4 Call Setup
Forced Directed Retry (Cause 20)
CAUSE 20: Forced Directed Retry
To activate FDR : EN_FORCED_DR = Enable AND EN_DR = Enable
AV_RXLEV_NCELL_DR(n) is calculated with the A_PBGT_DR window
If less than A_PBGT_DR samples are available
AV_RXLEV_NCELL_DR(n) is calculated with the available "n" samples and remaining "A_PBGT_DR n" are filled with -110 dBm
AV_RXLEV_NCELL_DR(n) > L_RXLEV_NCELL_DR(n)And EN_FORCED_DR = ENABLED
AV_RXLEV_NCELL_DR(n) > L_RXLEV_NCELL_DR(n)And EN_FORCED_DR = ENABLED
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4 Call Setup
FDR Parameters
L_RXLEV_NCELL_DR(n): level required in the neighboring cell n The parameter considered is the one set in the neighboring cell
The default value depends on the network architecture
See the next slide
Freelevel_DR(n): number of free TCH channels required in the neighboring cell n
The parameter considered is the one set in the neighboring cell
Default value = 0 to 4 TCHs (linked to the nb of TRXs)
(cf. Candidate Cell Evaluation)
A_PBGT_DR: average window Default value = 4 SACCHs
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4 Call Setup
Managing DR Parameters
Normal DR
Pro's: no radio problem as MS's remain within the service area of the new serving cell
Con's: poor probability of happening, as MS is already camping on the best server cell
Forced DR
Pro's: Probability of detecting a FDR depends on parameter settings.
Con's: Interference problems because MS is perhaps outside the cell normal service area
Umbrella cell
Micro cell
FDRcapture
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4 Call Setup
Access Strategy
Prevention of congestion in the old cells
MSs are sent in idle mode to the preferred cell
HO strategy favoring the preferred cell in dedicated mode
Prevention of congestion in the preferred cell
Forced Directed Retry to the old cells
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A dual layer network is considered
Umbrella cells 900
Micro cells 900
Set FDR parameters to avoid interference and allow a powerful TCH resource usage
Umbrella cells
Microcells
Time allowed:
10 minutes
4 Call Setup
Exercise
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1 1 83
5 Handover Strategies
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5 Handover Strategies
Objectives
1. Maximize capacity of the network, with:
Intelligent MS sharing between available resources
Avoid congestion of historical band (for old MS)
Consider traffic conditions of all layers
Use full capacity of new resources (1800 band is offering more channels)
Consider MS speed for layer discrimination
Avoid too many handovers
Degradation of voice quality
In order to ease traffic analysis, it is recommended to avoid too many handovers between layers.
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5 Handover Strategies
Objectives [cont.]
2. Insuring good quality communications and avoiding call drops
Send MS towards the layer that will provide the best QoS
Minimize the number of HO between cells for good speech Quality
Fast moving mobiles are handled by the macrocell layer
Identify a best target for emergency handovers cases
The tuning of the parameters will result in trade-offs
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5 Handover Strategies
Handover Algorithms
Next parts will detail available HO causes for multilayer network management
Standard Handovers
Multilayer and Multiband Handovers
Concentric cell "Interzone" Handovers
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5 Handover Strategies
Functional Entities
RadioLink Measurements
ActiveChannelPre-processing
Assignment of HO functions in the ALCATEL BSC
BSC
HO DetectionHO CandidateCell Evaluation
HO management
MSCHO protocol
BTS
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5 Handover Strategies
HO Causes
Standard HO causes
cause 2 : too low quality on the uplink
cause 3 : too low level on the uplink
cause 4 : too low quality on the downlink
cause 5 : too low level on the downlink
cause 6 : too large distance between the MS and the BTS
cause 15 : high interference on the uplink (intra-cell HO)
cause 16 : high interference on the downlink (intra-cell HO)
cause 26 : AMR channel adaptation HO (HR to FR)
cause 12 : power budget evaluation
cause 23 : traffic
cause 27 : AMR channel adaptation HO (FR to HR)
cause 28 : Fast traffic HO
cause 29 : TFO HO
cause 20 : FDR
EM
BC
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5 Handover Strategies
HO Causes [cont.]
HO causes for multilayer and multiband networks
cause 10 : too low level on the uplink in the inner zone
cause 11 : too low level on the downlink in the inner zone
cause 7 : consecutive bad SACCH frames received in a microcell
cause 17 : too low level on the uplink in a microcell compared to a high threshold
cause 18 : too low level on the downlink in a microcell compared to a high threshold
cause 13 : too high level on the uplink and the downlink in the outer zone
cause 14 : high level in the neighboring cell of a lower or indoor layer for slow mobile
cause 21 : high level in the neighboring cell in the preferred band
cause 24 : general capture
EM
BC
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5 Handover Strategies
HO Causes Priority
cause 7 : consecutive bad SACCH frames received in a microcell cause 17 : too low level on the uplink in a cell compared to a high threshold cause 18 : too low level on the downlink in a cell compared to a high threshold cause 2 : too low quality on the uplink cause 3 : too low level on the uplink cause 4 : too low quality on the downlink cause 5 : too low level on the downlink cause 6 : too large distance between the MS and the BTS cause 10 : too low level on the uplink in the inner zone cause 11 : too low level on the downlink the in inner zone cause 26 : AMR channel adaptation HO (HR to FR) cause 15 : high interference on the uplink (intra-cell HO) cause 16 : high interference on the downlink (intra-cell HO)
cause 21 : high level in the neighboring cell in the preferred bandcause 14 : high level in neighboring cell of a lower or an indoor layer cell for slow mobilecause 24 : general capturecause 12 : power budget evaluationcause 23 : traffic
cause 13 : too high level on the uplink and downlink in the outer zone cause 27 : AMR channel adaptation HO (FR to HR) cause 20 : Forced Directed Retry DR cause 28 : Fast traffic HO
EM
BC
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6 Main Standard Handover Algorithms
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6 Main Standard Handover Algorithms
Emergency Intercell Algorithms
Emergency intercell handovers
cause 2 : too low quality on the uplink
cause 3 : too low level on the uplink
cause 4 : too low quality on the downlink
cause 5 : too low level on the downlink
cause 6 : too large distance between the MS and the BTS
May be triggered
From any serving cell (any band, any zone, any layer)
Towards any neighbour, except the serving cell
Note : EM HO detected while in the inner zone of a cell
the outer zone is a candidate
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6 Main Standard Handover Algorithms
Handover Cause 2: UL Quality
CAUSE 2: too low quality on the uplink
Size of window for averaging quality: A_QUAL_HO
Size of window for averaging level: A_LEV_HO
AV_RXQUAL_UL_HO > L_RXQUAL_UL_H + OFFSET_RXQUAL_FH
and AV_RXLEV_UL_HO L_RXQUAL_UL_H + OFFSET_RXQUAL_FH
and AV_RXLEV_UL_HO
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6 Main Standard Handover Algorithms
Handover Cause 3: UL Level
CAUSE 3: too low level on the uplink
Size of window for averaging quality: A_QUAL_HO
Size of window for averaging level: A_LEV_HO
QUAL
LEV
AV_RXQUAL_UL_HO
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6 Main Standard Handover Algorithms
Handover Cause 4: DL Quality
CAUSE 4: too low quality on the downlink
Size of window for averaging quality: A_QUAL_HO
Size of window for averaging level: A_LEV_HO
QUAL
LEV
AV_RXQUAL_DL_HO > L_RXQUAL_DL_H + OFFSET_RXQUAL_FH
and AV_RXLEV_DL_HO L_RXQUAL_DL_H + OFFSET_RXQUAL_FH
and AV_RXLEV_DL_HO
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6 Main Standard Handover Algorithms
Handover Cause 5: DL Level
CAUSE 5: too low level on the downlink
Size of window for averaging quality: A_QUAL_HO
Size of window for averaging level: A_LEV_HO
QUAL
LEV
AV_RXQUAL_UL_HO
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6 Main Standard Handover Algorithms
Handover Cause 6: Distance
CAUSE 6 : Too long distance
Size of window for averaging distance : A_RANGE_HO
AV_RANGE_HO > U_TIME_ADVANCE
and EN_DIST_HO = ENABLED
AV_RANGE_HO > U_TIME_ADVANCE
and EN_DIST_HO = ENABLED
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6 Main Standard Handover Algorithms
Emergency Intracell Handovers
Emergency intracell handovers
cause 15 : high interference on the uplink (intra-cell HO)
cause 16 : high interference on the downlink (intra-cell HO)
May be triggered
From any serving cell (any band, any zone, any layer)
Towards only the serving cel
Note : If the MS is on a non-hopping TRX, the BSC will tend to allocate a TCH on another TRX.
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6 Main Standard Handover Algorithms
Handover Cause 15: UL Interference
CAUSE 15: High interference on the uplink
Size of window for averaging quality: A_QUAL_HO
Size of window for averaging level: A_LEV_HO
AV_RXQUAL_UL_HO > THR_RXQUAL_CAUSE_15 + OFFSET_RXQUAL_FH
and AV_RXLEV_UL_HO > RXLEV_UL_IH
and EN_CAUSE_15 = ENABLED
and [ no previous intracell handover for this connection failed or EN_INTRACELL_REPEATED = ENABLED ]
AV_RXQUAL_UL_HO > THR_RXQUAL_CAUSE_15 + OFFSET_RXQUAL_FH
and AV_RXLEV_UL_HO > RXLEV_UL_IH
and EN_CAUSE_15 = ENABLED
and [ no previous intracell handover for this connection failed or EN_INTRACELL_REPEATED = ENABLED ]
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6 Main Standard Handover Algorithms
Handover Cause 16: DL Interference
CAUSE 16: High interference on the downlink
Size of window for averaging quality: A_QUAL_HO
Size of window for averaging level: A_LEV_HO
AV_RXQUAL_DL_HO > THR_RXQUAL_CAUSE_16 + OFFSET_RXQUAL_FH
and AV_RXLEV_DL_HO > RXLEV_DL_IH
and EN_CAUSE_16 = ENABLED
and [ no previous intracell handover for this connection failed or EN_INTRACELL_REPEATED = ENABLED ]
AV_RXQUAL_DL_HO > THR_RXQUAL_CAUSE_16 + OFFSET_RXQUAL_FH
and AV_RXLEV_DL_HO > RXLEV_DL_IH
and EN_CAUSE_16 = ENABLED
and [ no previous intracell handover for this connection failed or EN_INTRACELL_REPEATED = ENABLED ]
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6 Main Standard Handover Algorithms
New Parameters for Causes 15 & 16
CAUSE 15 and CAUSE 16:
THR_RXQUAL_CAUSE_15 (or 16) and EN_CAUSE_15 (or 16) are specific to variable computed by the BSC :
THR_RXQUAL_CAUSE_15 (or 16) =
L_RXQUAL_XX_H for a non AMR call (same threshold as CAUSE 2 or CAUSE 4)
L_RXQUAL_XX_H_AMR for an AMR call
EN_ CAUSE _15 (or 16) =
EN_INTRA_XX for a non-AMR call
EN_INTRA_XX_AMR for an AMR call
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6 Main Standard Handover Algorithms
Causes 15 & 16: specific case of concentric cells
For an MS in the INNER zone, if cause 15 or 16 is triggered:
TCH may be allocated in the outer zone or in the inner zone
For an MS in the OUTER zone, if cause 15 or 16 is triggered:
TCH is always allocated in the outer zone
INNER
OUTER
-
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6 Main Standard Handover Algorithms
Handover Cause 12: Power Budget
Definition of PBGT HO :
Comfort handover type, no matter of emergency
Possible targets depend on the cells layer type :
Single or UpperSingle or UpperSingle
MS Speed = FASTMS Speed FAST
Indoor
Lower
Single or Upper
Target Layer Type
Upper or Indoor
Upper or Lower
Single or Upper
Serving Layer Type
Indoor
Lower
Upper
If the MS is measured as fast, HO preferably towards upper cells with
low traffic load
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6 Main Standard Handover Algorithms
Handover Cause 12: Power Budget [cont.]
Definition of PBGT HO :
Possible targets depend also on the cells band type :
GSMAnyGSM
EN_MULTIBAND_PBGT_HO= Disable
EN_MULTIBAND_PBGT_HO= Enable
Any
Target Band Type
DCS
Serving Band Type
(MS not in inner zone of a MB cell)
DCS
A multiband cell is "GSM" if the outer zone is in GSM (cf. note)
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6 Main Standard Handover Algorithms
Handover Cause 12: Power Budget [cont.]
Definition of PBGT HO :
And if the MS is in the inner zone of a multiband concentric cell :
GSM-DCSAnyGSM
EN_MULTIBAND_PBGT_HO= Disable
EN_MULTIBAND_PBGT_HO= Enable
Any
Target Frequency Band
GSM-DCS
Serving Band Type
(MS in inner zone of a MB cell)
DCS
When in the MB inner zone, it is possible to force PBGT HO only towards other
MB cell.
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6 Main Standard Handover Algorithms
Handover Cause 12: Power Budget [cont.]
If EN_MULTIBAND_PBGT_HO = disable
Single 900
Upper 900
900
900 1800
indoor900
Upper 1800
900
mini1800
Upper 900
Single 1800
900 1800
indoor900
mini900
fast
fast
fast
fast
fast
Upper
Upper
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6 Main Standard Handover Algorithms
Handover Cause 12: Power Budget [cont.]
If EN_MULTIBAND_PBGT_HO = enable
Single 900
Upper 900
900
900 1800
indoor900
Upper 1800
900
mini1800
Upper 900
Single 1800
900 1800
indoor900
mini900
Upper
Upper
fast
fast
fast
fast
fast
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6 Main Standard Handover Algorithms
Handover Cause 12: Power Budget [cont.]
Based on Power budget equation
Size of window for level averaging: A_PBGT_HO
PBGT(n) = AV_RXLEV_NCELL(n) - AV_RXLEV_PBGT_HO
- (BS_TXPWR_MAX AV_BS_TXPWR_HO)
- (MS_TXPWR_MAX(n) MS_TXPWR_MAX)
- PING_PONG_MARGIN(n, call_ref)
PBGT(n) = AV_RXLEV_NCELL(n) - AV_RXLEV_PBGT_HO
- (BS_TXPWR_MAX AV_BS_TXPWR_HO)
- (MS_TXPWR_MAX(n) MS_TXPWR_MAX)
- PING_PONG_MARGIN(n, call_ref)
(A)
(B)
(C)
(D)
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6 Main Standard Handover Algorithms
Handover Cause 12: Power Budget [cont.]
A Handover cause 12 is detected only if the following conditions are met :
Size of window for level averaging: A_PBGT_HO
if EN_TRAFFIC_HO(0,n) = DISABLED
then PBGT(n) > HO_MARGIN(0,n) + OFFSET_HO_MARGIN_INNER (*)
and AV_RXLEV_PBGT_HO RXLEV_LIMIT_PBGT_HO
and EN_PBGT_HO = ENABLED
if EN_TRAFFIC_HO(0,n) = DISABLED
then PBGT(n) > HO_MARGIN(0,n) + OFFSET_HO_MARGIN_INNER (*)
and AV_RXLEV_PBGT_HO RXLEV_LIMIT_PBGT_HO
and EN_PBGT_HO = ENABLED
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6 Main Standard Handover Algorithms
Handover Cause 12: Power Budget [cont.]
In case the feature "Traffic HO" is enabled, the previous condition is modified :
Size of window for level averaging: A_PBGT_HO
if EN_TRAFFIC_HO(0,n) = ENABLED
then PBGT(n) > HO_MARGIN(0,n) + OFFSET_HO_MARGIN_INNER (*)+ max(0, DELTA_HO_MARGIN(0,n))
and AV_RXLEV_PBGT_HO RXLEV_LIMIT_PBGT_HO
and EN_PBGT_HO = ENABLED
if EN_TRAFFIC_HO(0,n) = ENABLED
then PBGT(n) > HO_MARGIN(0,n) + OFFSET_HO_MARGIN_INNER (*)+ max(0, DELTA_HO_MARGIN(0,n))
and AV_RXLEV_PBGT_HO RXLEV_LIMIT_PBGT_HO
and EN_PBGT_HO = ENABLED
max(0, DELTA_HO_MARGIN(0,n)) is always positive it increases the HO_MARGIN(O,n)max(0, DELTA_HO_MARGIN(0,n)) is always positive it increases the HO_MARGIN(O,n)
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6 Main Standard Handover Algorithms
Handover Cause 12: Power Budget [cont.]
DELTA_HO_MARGIN(0,n): evaluated according to the traffic situation of the serving cell and the neighboring cell n (Traffic_load(n)) in the following way:
Philosophy:
This mechanism aims at penalizing cause 12 detection when the traffic in the serving cell is low and is high in the cell n
If Traffic_load(0) = high and Traffic_load(n) = low, DELTA_HO_MARGIN(0,n) = - DELTA_DEC_HO_MARGIN
If Traffic_load(0) = low and Traffic_load(n) = high, DELTA_HO_MARGIN(0,n) = + DELTA_INC_HO_MARGIN
Else DELTA_HO_MARGIN(0,n) = 0
If Traffic_load(0) = high and Traffic_load(n) = low, DELTA_HO_MARGIN(0,n) = - DELTA_DEC_HO_MARGIN
If Traffic_load(0) = low and Traffic_load(n) = high, DELTA_HO_MARGIN(0,n) = + DELTA_INC_HO_MARGIN
Else DELTA_HO_MARGIN(0,n) = 0
(A)
(B)
(C)
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6 Main Standard Handover Algorithms
Handover Cause 12: Power Budget [cont.]
What is the traffic_load() ?
Computed for every cell by the BSC
Not available for neighbour cells that are external (different BSC's)
Can have three values:
HIGH: cell is loaded
LOW: cell is unloaded
INDEFINITE: cell load is neither loaded nor unloaded, or unknown
Modified according to the long term traffic evaluation algorithm using the following parameters:
A_TRAFFIC_LOAD, N_TRAFFIC_LOAD : averaging windows
HIGH_TRAFFIC_LOAD, IND_TRAFFIC_LOAD, LOW_TRAFFIC_LOAD: load thresholds
TCH_INFO_PERIOD: cannot be modified (5 s)Annex 1
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6 Main Standard Handover Algorithms
Handover Cause 12: Inter-band situation
Separated 900 1800 coverages
Allow the flow of PBGT HO between the 2 bands
EN_MULTIBAND_PBGT_HO = enable
1800 cells 900 cells
EN_MULTIBAND_PBGT_HO = enable or disable
HO_MARGIN(0,n) =5 dB HO_MARGIN(0,n) = 5 dB
HO_MARGIN(0,n) = 8 dB
EN_MULTIBAND_PBGT_HO = enable
HO_MARGIN(0,n) = 2 dB
EN_MULTIBAND_PBGT_HO = enable
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6 Main Standard Handover Algorithms
Handover Cause 12: Inter-band situation [cont.]
Common 900 1800 coverages
Solution 1 : Allow the exit from "border 1800", but use other HO causes to manage "core 1800"
macro 900
macro 1800
HO_MARGIN(0,n) = 5 dB
HO_M(1800,900)
= 2 dB
"Border" strategy
Smooth exit of the 1800 area
EN_MULTIBAND_PBGT_HO = Enable"Core" strategy
Prevent PBGT HO, to keep MS in 1800
EN_MULTIBAND_PBGT_HO = Disable
HO_MARGIN(900,1800)
= 8 dB
HO_MARGIN(0,n) = 5 dB
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6 Main Standard Handover Algorithms
Handover Cause 12: Inter-band situation [cont.]
Common 900 1800 coverages
Solution 2 : Manage all intra-layer HO with HO cause 12.
macro 900
macro 1800
HO_M = 2 dB
"Border" strategy
Smooth exit of the 1800 area
EN_MULTIBAND_PBGT_HO = Enable"Core" strategy
Allow PBGT HO, favour MS in 1800
EN_MULTIBAND_PBGT_HO = Enable
HO_M = 8 dB
HO_M(900,900) = 5 dB
HO_M(1800,900)
= 8dB
HO_M(900,1800)
= 2dB
HO_M(1800,1800) = 5 dB
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6 Main Standard Handover Algorithms
HO Cause 12: Tuning of Microcells Parameters
HO_MARGIN(0,n) optimization
Not triggering too many HOs(ping-pong)
Not triggering HO to a transient cell (for example, the perpendicular cell at a crossroads)
Avoid emergency HO to the umbrella if there is an available microcell (after a street corner).
Micro 1Micro 2
Micro 3
PBGT HO between micro cells 1, 2
-110
-100
-90
-80
-70
-60
-50
1 3 5 7 9
11
13
15
17
19
rxlev(cell 1)
rxlev(cell 2)
rxlev(cell 3)
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6 Main Standard Handover Algorithms
HO Cause 12: Tuning of Microcells Parameters [cont.]
HO_MARGIN(0,n) Avoid ping-pong HO in urban environment
Avoid emergency HO after street corners
Avoid transcient PBGT HO
Default value: up to 10 dB in dense urban microcellular area, with short A_PBGT_HO.
Optimized: can be reduced to 5dB or 0dB when applying an anti ping-pong mechanism and long A_PBGT_HO.
A_PBGT_HO To find a compromise with HO_MARGIN(0,n)
Default value: 8 SACCHs for urban microcells, 6 for dense urban
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6 Main Standard Handover Algorithms
HO Cause 12: Tuning of Microcells Parameters [cont.]
HO_MARGIN optimization
if HO_MARGIN(0,n) > 5dB
PBGT HO delayed
C/I might drop below -9dB
in case of adjacent frequencies between 2 neighbouring microcells, degradation of voice quality
if HO_MARGIN(0,n) 5dB (0dB)
adjacent frequencies between neighbouring microcells can be used
BUT A_PBGT_HO should be increased
AND the anti ping-pong mechanism should be applied (PING_PONG_HCP & T_HCP)
BTS1
BTS2
Building
Interferer
fn
fn+1
Area of potential interferences: (C/I)adj < -6dB
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6 Main Standard Handover Algorithms
Cause 12: Speed Discrimination in Lower/Indoor
Transfer of fast MSs from lower or indoor layers to upper layer
If EN_SPEED_DISC = ENABLED
Traffic Load = low Traffic Load low
HO
HO (12) HO (12) HO (12)
HO (12)
MIN_CONNECT_TIME
At call setup: C_DWELL = 0 and is incremented by 1 every MEASUREMENT REPORTMS_SPEED is set to indefinite
After 1st HO: MS_SPEED is kept at indefinite, and C_DWELL reinits to 0Next HO: MS_SPEED is set to fast if
C_DWELL < 2 x MIN_CONNECT_TIMEHO is a Power Budget HO (cause 12)EN_SPEED_DISC = ENABLED in serving cell
Otherwise MS_SPEED is kept at indefinite and C_DWELL reinits to 0
At call setup: C_DWELL = 0 and is incremented by 1 every MEASUREMENT REPORTMS_SPEED is set to indefinite
After 1st HO: MS_SPEED is kept at indefinite, and C_DWELL reinits to 0Next HO: MS_SPEED is set to fast if
C_DWELL < 2 x MIN_CONNECT_TIMEHO is a Power Budget HO (cause 12)EN_SPEED_DISC = ENABLED in serving cell
Otherwise MS_SPEED is kept at indefinite and C_DWELL reinits to 0
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6 Main Standard Handover Algorithms
Exercise
Draw arrows to indicate among which cells the HO cause 12 can be detected
UMBRELLA
LOWER
INDOOR
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6 Main Standard Handover Algorithms
Handover Cause 23: Traffic
The aim of this cause is to speed-up HO detection when
The serving cell is loaded
The target cell is unloaded
Counter-reaction of cause 12
Checked between :
LAYER :
Cells with the same CELL_LAYER_TYPE
BAND :
If EN_MULTIBAND_PBGT_HO = disable Cells with the same CELL_BAND_TYPE
if MS in inner zone of a multiband cell, it can only go to another multiband cell
If EN_MULTIBAND_PBGT_HO = enable Any CELL_BAND_TYPE
CAUSE 23
CAUSE 12
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6 Main Standard Handover Algorithms
Handover Cause 23: Traffic [cont.]
CAUSE 23: Traffic Handover
Size of window for level average: A_PBGT_HO
DELTA_HO_MARGIN(0,n) uses the same algorithm as in p.77.
DELTA_HO_MARGIN(0,n) < 0 dB
AND PBGT(n) > HO_MARGIN(0,n) + OFFSET_HO_MARGIN_INNER+ DELTA_HO_MARGIN(0,n)
AND EN_TRAFFIC_HO(0,n) = ENABLED
DELTA_HO_MARGIN(0,n) < 0 dB
AND PBGT(n) > HO_MARGIN(0,n) + OFFSET_HO_MARGIN_INNER+ DELTA_HO_MARGIN(0,n)
AND EN_TRAFFIC_HO(0,n) = ENABLED
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6 Main Standard Handover Algorithms
Handover Cause 28: Fast Traffic HO
CAUSE 28: Fast Traffic Handover
Push out of a cell a mobile in dedicated mode to allow a queued request to be served in the serving cell
May be triggered
From any non-concentric cell OR concentric outer zone
Towards any cell except the serving one
HO
New call attempt Most appropriate MS to be pushed out
Congested cell
New call attempt
HO
Most appropriate MS
to be pushed out
Upper Layer Cell
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6 Main Standard Handover Algorithms
Handover Cause 28: Fast Traffic HO [cont.]
CAUSE 28: Fast Traffic Handover
Cause 28 is only checked if the channel of the candidate MS can support the channel rate (HR or FR) required by the queued request:
HO is triggered when a request is queued at the top of the queue
FR (whatever the TRX type)FR
HR
or
FR on dual rate TRX
HR
Candidate MSQueued Request
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6 Main Standard Handover Algorithms
Handover Cause 28: Fast Traffic HO [cont.]
CAUSE 28: Fast Traffic Handover
Size of window for averaging level: A_PBGT_DR
Same thresholds and window as Cause 20 (FDR)
EN_CAUSE_28 is an internal HOP process variable, ENABLED when a request is queued
AV_RXLEV_NCELL(n) > L_RXLEV_NCELL_DR(n) + max (0, [MS_TXPWR_MAX(n) - P])
and t(n) > FREELEVEL_DR(n)
and EN_CAUSE_28 = ENABLED
and EN_FAST_TRAFFIC_HO = ENABLED
AV_RXLEV_NCELL(n) > L_RXLEV_NCELL_DR(n) + max (0, [MS_TXPWR_MAX(n) - P])
and t(n) > FREELEVEL_DR(n)
and EN_CAUSE_28 = ENABLED
and EN_FAST_TRAFFIC_HO = ENABLED
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Detection of cause 12
Parameters settings
No Power Control DL, no anti ping-pong
EN_PBGT_HO = enable
EN_TRAFFIC_HO(0,n) = disable
HO_MARGIN(0,n) = 5 dB
RXLEV_LIMIT_PBGT_HO = -47 dBm
BS_TXPWR_MAX_INNER = 0 dB
OFFSET_HO_MARGIN_INNER = 0 dB
In each case, determine if cause 12 is detected or not
30 minutes
6 Main Standard Handover Algorithms
Exercise
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Is cause 12 triggered?
EN_MULTIBAND_PBGT_HO = ENABLE
6 Main Standard Handover Algorithms
Exercise [cont.]
9009001800900Band
FastFastSlowIndMS speed
Cause 12 ?
PBGT ?
-80 dBm-65 dBm- 65 dBm-80 dBmRx_Lev(n)
HIGHLOWLOWINDTraffic(n)
MicroUmbrellaUmbrellaSingleType
Target
-90 dBm-90 dBm- 90 dBm-85 dBmRx_Lev(0)
NoYesYesNoEN_SPEED_DISC
900900900900Band
MiniMicroMicroSingleType
Source
Case 4Case 3Case 2Case 1Inputs
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6 Main Standard Handover Algorithms
Exercise [cont.]
Is cause 12 triggered?
EN_MULTIBAND_PBGT_HO = DISABLE
Cause 12 ?
PBGT ?
-65 dBm-65 dBm-65 dBm-70 dBm-80 dBmRx_Lev(n)
9009009001800900Band
Multiband
UpperSingleSingleSingleSingleType
Target
-90 dBm-90 dBm-90 dBm-85 dBm-85 dBmRx_Lev(0)
InnerOuterInner------Zone
900900900900900Band
Multiband
Upper
Multiband
Upper
Multiband
UpperSingleSingleType
Source
Case 5Case 4Case 3Case 2Case 1Inputs
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6 Main Standard Handover Algorithms
Exercise [cont.]
Is cause 12 triggered?
EN_MULTIBAND_PBGT_HO = ENABLE
Cause 12 ?
PBGT ?
-65 dBm-65 dBm-65 dBm-70 dBm-80 dBmRx_Lev(n)
9009009001800900Band
Multiband
UpperSingleSingleSingleSingleType
Target
-90 dBm-90 dBm-90 dBm-85 dBm-85 dBmRx_Lev(0)
InnerOuterInner------Zone
900900900900900Band
Multiband
Upper
Multiband
Upper
Multiband
UpperSingleSingleType
Source
Case 5Case 4Case 3Case 2Case 1Inputs
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7 Emergency Handover Algorithms for MBML Networks
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7 Emergency Handover Algorithms for MBML Networks
Emergency Handovers: Introduction
In a hierarchical network, the MS can camp in any layer. Each layer is characterized by a certain cell type.
Depending on the dimension type, the BSC is able to trigger some specific "microcell" emergency handovers in order to save the call.
Micro
Micro
Macro
Macro
Macro
Dimension Type
YESYESMicro
NOYESSingle
Micro
(7,17,18)
Standard
(2,3,4,5,6)
YES
YES
YES
Available Emergency HO causes
YES
NO
NO
Serving Cell Type
Indoor
Mini
Umbrella
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7 Emergency Handover Algorithms for MBML Networks
Emergency Handovers: Introduction [cont.]
Recommended strategies :
An MS is located in a micro or an indoor cell
During an emergency HO, the MS is directed preferably towards an upper or a single cell
An MS is located in a mini cell
During an emergency HO, the MS is directed preferably towards neighboring mini cells
in
umbrella single
mini
umbrella
mini
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7 Emergency Handover Algorithms for MBML Networks
Emergency Handovers Specific to Microcells
Emergency handovers specific to microcells
cause 7 : consecutive bad SACCH frames received in a microcell
cause 17 : too low level on the uplink in a microcell compared to a high threshold
cause 18 : too low level on the downlink in a microcell compared to a high threshold
May be triggered
From microcells only (cell_dimension_type = micro)
Outdoor microcell (micro layer)
Indoor microcell (indoor layer)
Towards any cell except the serving one
Note : If the MS in inner zone of a multiband cell, the serving cell is a candidate
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7 Emergency Handover Algorithms for MBML Networks
Microcell Emergency Handovers
CAUSE 7: consecutive bad SACCH frames received in a microcell
N_BAD_SACCH Rule : "Radio Link Recovery shall be triggered before the handover"
N_BAD_SACCH > RADIOLINK_TIMEOUT_BS - N_BSTXPWR_M
Default values:
RADIOLINK_TIMEOUT_BS = 18 SACCH
N_BSTPWR_M = 15 SACCH
N_BAD_SACCH = 4 SACCH
Last N_BAD_SACCH frames received are not correct
and EN_MCHO_RESCUE = ENABLE
Last N_BAD_SACCH frames received are not correct
and EN_MCHO_RESCUE = ENABLE
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