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All rights reserved 2005, Alcatel

Multilayer GSM Network Radio Optimization / B9

EVOLIUM Base StationSubsystem

Multilayer GSM Network Radio

Optimization / B9

TRAINING MANUAL

3FL12033ABAAWBZZAEdition 02 - May 2006

Copyright 2005 by Alcatel - All rights reservedPassing on and copying of this document, use and communication of its

contents not permitted without written authorization from Alcatel


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All rights reserved 2005, AlcatelMultilayer GSM Network Radio Optimization / B9

2

Legal Notice

Switch to notes view!Safety WarningBoth lethal and dangerous voltages are present within the equipment. Do not wear conductive jewelry while

working on the equipment. Always observe all safety precautions and do not work on the equipment alone.

Caution

The equipment used during this course is electrostatic sensitive. Please observe correct anti-static precautions.

Trade Marks

Alcatel and MainStreet are trademarks of Alcatel.

All other trademarks, service marks and logos (Marks) are the property of their respective holders includingAlcatel. Users are not permitted to use these Marks without the prior consent of Alcatel or such third partyowning the Mark. The absence of a Mark identifier is not a representation that a particular product or servicename is not a Mark.

Copyright

This document contains information that is proprietary to Alcatel and may be used for training purposesonly. No other use or transmission of all or any part of this document is permitted without Alcatels writtenpermission, and must include all copyright and other proprietary notices. No other use or transmission of allor any part of its contents may be used, copied, disclosed or conveyed to any party in any mannerwhatsoever without prior written permission from Alcatel.

Use or transmission of all or any part of this document in violation of any applicable Canadian or otherlegislation is hereby expressly prohibited.

User obtains no rights in the information or in any product, process, technology or trademark which itincludes or describes, and is expressly prohibited from modifying the information or creating derivative works

without the express written consent of Alcatel.

Alcatel, The Alcatel logo, MainStreet and Newbridge are registered trademarks of Alcatel.

All other trademarks are the property of their respective owners. Alcatel assumes no responsibility for theaccuracy of the information presented, which is subject to change without notice.

2005 Alcatel. All rights reserved.

Disclaimer

In no event will Alcatel be liable for any direct, indirect, special, incidental or consequential damages,including lost profits, lost business or lost data, resulting from the use of or reliance upon the information,whether or not Alcatel has been advised of the possibility of such damages.

Mention of non-Alcatel products or services is for information purposes only and constitutes neither anendorsement nor a recommendation.

Please refer to technical practices supplied by Alcatel for current information concerning Alcatel equipmentand its operation.


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Product Line EVOLIUMBase Station Subsystem

Course Title Multilayer GSM Network Radio Optimization / B8

Course Reference 3FL 12033 ABAA - AUE

Audience

Radio Network Engineers (operator or Alcatel staff) in

charge of optimizing a hierarchical network.

Objectives

During the course, the trainee will be able todescribe the specific radio algorithms in multi-layer networks in order to enhance the offeredQoS.

By the end of the course, the participant will beable to:

- Describe the concepts and strategy of hierarchicalnetworks.

- Describe the specific type of cells implemented in

hierarchical networks.- Describe the specific radio algorithms used in the

Alcatel BSS in a hierarchical network.

- Propose default parameter values for the cells of ahierarchical network using these algorithms.

- Propose a list of specific indicators to monitor QoSand traffic in a hierarchical network.

Note: Radio Network Planning issues like micro sitedetection, site planning, frequency planning are notincluded.

Prerequisites

Training module Introduction to GSM QoS and TrafficLoad Monitoring (3FL 10491 ABAAAUE) andIntroduction to Radio Fine Tuning (3FL 10493

ABAAAUE) or equivalent level.

Training Methods

Theory / Practice.

Language

English, French

Duration

3 Days

Location

Alcatel University or Customer Premises.

Number of participants

Maximum 8

Course content

1 Multi-layer Network Architecture

1.1 Concepts and strategies 1.2 Cellular network architecture

1.3 Choosing a relevantarchitecture

1.4 Requirements

2 Algorithms and AssociatedParameters

2.1 Introduction

2.2 Idle mode selection andreselection

2.3 Call setup

2.4 Handover strategies 2.5 Main standard handover

algorithms

2.6 HO algorithms for multi-layernetworks

2.7 Candidate cells evaluation

3 Creating a Multi-layer Network

3.1 Adding a micro cellular layer inan existing network for traffic andcoverage increase

3.2 Adding hot spot microcells fortraffic

3.3 Adding indoor microcells forcoverage

3.4 Monitoring QoS in a multi-layernetwork

4 Case studies

4.1 Radar cell

4.2 Symmetric microcells at streetcorner

4.3 Asymmetric microcells at streetcorner

4.4 Indoor microcell within a

monolayer network 4.5 Trilayer network: indoor cell

within a multi-layer network

4.6 Indoor cell congestion

4.7 Transforming a microcell intoan indoor cell

4.8 Picocells in skyscrapers


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Table of Contents [cont.]

Switch to notes view!

This page is left blank intentionally


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1 MULTI-LAYER NETWORK ARCHITECTURE


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Session presentation

Objective: to be able to define relevant architectures formulti-layer networks design

Program:

1.1 Concepts and strategies

1.2 Cellular network architecture

1.3 Choosing a relevant architecture

1.4 Requirements


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Multi-layer 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 outdoormicrocells)

While keeping a good QoS

confined coverage for microcells, with less interference

less congestion


Introduction to multi-layer networks

Since B7:

new HW capabilities with Cell split support

enhancement of QoS monitoring capabilities with counters split per TRX


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Alcatel is providing multi-layer solutions Since R3.1: mini & microcells

Improvements in B3.1 (smart speed discrimination) Improvements in B6.2 (external Directed Retry)

Improvements in B7 (indoor layer introduction)


Support of multi-layer features


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Multi-layer networks can be introduced as continuous layer orhotspots, for:

Capacity increase Coverage increase

Indoor solution

All types of mobiles can use both layers


Network strategy

If the speed discrimination process is activated then Phase 2 MSs will be sent more or less quickly according

to the load of the umbrella cell.


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Conventional Single cell

Concentric cell Extended cell

Multi-band cell

Hierarchical: introducing Upper and Lower cell layers Indoor cell

Micro cell

Mini cell

Umbrella cell


Cell environment


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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


Cell profile


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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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Multi-band Cell profiles

PGSM-DCS1800 orEGSM-DCS1800

DCSNormalConcentricIndoorMicroDCS multiband indoor micro cell


GSMNormalConcentricIndoorMicroGSM multiband indoor micro cell


DCSNormalConcentricUpperMacroDCS multiband umbrella cell


GSMNormalConcentricUpperMacroGSM multiband umbrella cell


DCSNormalConcentricLowerMacroDCS multiband mini cell


GSMNormalConcentricLowerMacroGSM multiband mini cell


DCSNormalConcentricLowerMicroDCS multiband micro cell


GSMNormalConcentricLowerMicroGSM multiband micro cell


DCSNormalConcentricSingleMacroDCS multiband single cell

PGSM-DCS1800 orEGSM-DCS1800GSMNormalConcentricSingleMacroGSM multiband single cell

Frequency rangeCell band

typeCell

rangeCell partition

typeCell layer

typeCell dimension

type

Parameters

Cell Profile


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Cell profiles: example


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Multi-layer concept: 3 available layer types

All these cells can be or not operating in the same band and defined asconcentric cells


Concept

mini

umbrella

micro

indoor

micro micro

umbrella

micro

indoor

single

mini

umbrellaUPPER

SINGLE

LOWER

INDOOR

3 layers are defined in the system, but more layers can be created by parameter tuning. For example,

skyscrapers specific configuration is made up of several consecutive layers designed with cells of the samesystem layer.

Indoor layer has been introduced in B7.


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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


Microcell classes

Indoor Microcell

Border Microcell

Inner MicrocellHotspot Microcell

Defining microcell classes is a very efficient way to set network parameters. It avoids defining a specific

configuration for each cell.


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1.4 Requirements


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A multi-layer architecture can be built over all types of Hardware

Since R3.1

Microcell feature is NOT reserved to micro BTS!

Improvement in B6.2 with external Directed Retry

From R3.1 to B4.1, since Directed Retry was only Internal:

microcells had to be introduced within umbrella BSC

OR microcells were barred (traffic allocation was done by handover fromumbrella cells)

Since B6.2, External Directed Retry is available

Microcells and Umbrella cells can belong to different BSCs

1.4 Requirements

Software & Hardware requirements


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2 ALGORITHMS AND ASSOCIATEDPARAMETERS


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2 ALGORITHMS AND ASSOCIATED PARAMETERS

Session presentation

Objective: to be able to describe algorithms dedicated tomulti-layer networks management

Program:

2.1 Introduction

2.2 Idle mode selection and reselection

2.3 Call setup

2.4 Handover strategies

2.5 Main standard handover algorithms

2.6 Handover algorithms for multi-layer networks

2.7 Candidate cell evaluation


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2.1 Introduction


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With the introduction of new feature and algorithms:

Multi-layer

Designing, managing and monitoring complex networks is more difficult,

as all these features will interact

An in-depth knowledge of all available algorithms is necessary to understand

all possibilities and difficulties. A relevant choice of architecture and parameters

settings will precede the introduction of a new layer in the existing network

2.1 Introduction

Justification


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In all this document

System parameters (can be set at the OMC-R level) will always be written inBLUE BOLD FONT

Variables (averages, internal system variables, etc.) will be typed in NORMAL

FONT

Light blue font highlights important points

2.1 Introduction

Typing conventions


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Adding a new layer is a powerful way of increasing network capacity ifthe 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 preferredcell

Really increase capacity

Maintain high QoS level, without creating extra HO


Strategy


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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 is too low

The MS cannot decode downlink messages

The current cell is becoming forbidden (e.g. barred)

The MS cannot access the cell

there is a better cell, regarding C2 criterion


Selection and reselection principles

Note:

Cell selection (first selection) is performed using C1 criterion only (the chosen cell is the one with the best C1)

Reselection is done using the mechanisms referenced above.

e.g., the MS cannot access the cell.

It can be linked to SDCCH congestion, filtering of CHARQD due to TA greater than RACH_TA_FILTER, radioaccess problem during the Radio Link Establishment phase.

If SDCCH is to be seized for LU purpose, the MS will reselect on another cell.

If SDCCH is seized for something else (e.g., MOC), the MS may reselect (this is up to the MSvendor choice!!!). Some MSs do nothing. Call will never be possible. Some others do reselect. In thatcase, the user has to reattempt his call (after the reselection, but before the MS is back to the original

cell due to better C2, etc. (done after 5 s, etc.)).


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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 thelist of highest priority


Cell Selection with CBQ (1/3)


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Example: highest priority set on microcell

The MS will select the microcell (if available, C1>0), whatever the level of themacrocell



2525microcellCELL_BAR_QUALIFY = 0

2020

macrocell

CELL_BAR_QUALIFY = 1


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WARNING: usage of CELL_BAR_QUALIFY:

interacts with CELL_BAR_ACCESSA 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




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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


C1 criterion (1/2)


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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


C1 criteria (2/2)


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C2 IfCELL_RESELECT_PARAM_IND= not present THEN C2=C1 else

C2 = C1 + CELL_RESELECT_OFFSET -TEMPORARY_OFFSET (T)(if PENALTY_TIME 31)

- if T > PENALTY_TIME, TEMPORARY_OFFSET(T) = 0

- used to avoid locating on transient cell

- CELL_RESELECT_OFFSET used to favor a cell among other (e.g. micro-cell vs.umbrella, once T > PENALTY_TIME)

Or C2 = C1 -CELL_RESELECT_OFFSET(if PENALTY_TIME = 31)

- CELL_RESELECT_OFFSET used to handicap some cells among others

One reselection criterion is comparison with C2 C2neighboring > C2current if cells belong to the same LA

C2neighboring > C2current+CELL_RESELECT_HYSTERESIS if cells fromdifferent LA


C2 criterion

The use of a second formula (Penalty_time = 31) is restricted to very special cases, as we do not like to

penalize a cell. If a cell is parametered with PT=31, it will be penalized compared to ALL its neighboringcells. To penalize a cell compared to one neighboring cell, one should better boost the neighboring cell(using first formula).

The first formula is very useful to favor an indoor cell or a microcell.


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CELL_RESELECT_PARAM_IND C2 parameters are broadcast if = 1 (default)

otherwise C2 = C1

PENALTY_TIME 0 to 31, =20s + 20s step, default value = 0

From 0=20s to 30=620 s, plus 31: infinite penalty

CELL_RESELECT_OFFSET 0 to 63, 2 dB step, default value = 0

From 0 dB to 126 dB

TEMPORARY_OFFSET 0 to 7, 10 dB step, default value = 0

From 0 dB to 60 dB, plus 7: infinite dB


C2 parameters


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Application

MINIMINI

MINI 900

CELL_RESELECT_OFFSET = 20

dBTEMPORARY_OFFSET = 0 dB

PENALTY_TIME = 0 (20 s)UMBUMB

UMBRELLA 900

CELL_RESELECT_OFFSET = 0 dB

TEMPORARY_OFFSET = 0 dB

PENALTY_TIME = 0 (20 s)

C2(MINI) = C1(MINI) + 20

C2(900) = C1(900)

=> the reselection of the mini cell is favored


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2.3 Call setup


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Call setup is to be made on the cell selected in idle mode

Priorities have been defined with idle mode parameters

MSs are sent to the preferred cell

Lower layers

What is the risk??

2.3 Call setup

Principles


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The risk is to have congestion in the preferred cell!

Old cells (old layer capacity) are unloaded

as all MSs are sent to new cells

This phenomenon is amplified by handovers behavior

Dual layer 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

2.3 Call setup

Congestion in the preferred cell


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2.3 Call setup

Algorithms principles (1/3)

new

capacity

Trafficincrease

old

capacity


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2.3 Call setup


new

capacity

Water Valve with filter:

Dual layer algorithms

Trafficincrease

old

capacity


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2.3 Call setup


new

capacity

Water Pump:Forced

Directed Retry

Trafficincrease

old

capacity


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A Directed Retry:

Is an SDCCH to TCH intercell handover

Is triggered during a call setup procedure

If the serving cell is completely congested, the MS is allocated an SDCCH

If no TCH is available, the MS is queued

Under certain conditions, the MS obtains a TCH in another cell

SDCCH-TCH handover on:

better condition or emergency causes = Directed Retry

cause 20 = Forced Directed Retry

Internal and External Directed Retries are possible (since B6.2)

2.3 Call setup

Directed Retry principles


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Directed Retry

Set on a per cell basis with parameter EN_DR

Same behavior as TCH HO

Intercell handover causes are checked (i.e. all HO causes except 10, 11 and13 (concentric cells) and causes 15 and 16 (intracell HO))

candidate cell evaluation process: same as for TCH HO

2.3 Call setup

Directed Retry


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CAUSE 20: Forced Directed Retry

AV_RXLEV_NCELL_DR(n) > L_RXLEV_NCELL_DR(n)

AndEN_FORCED_DR = ENABLED

EN_FORCED_DR value is only relevant if EN_DR = true

AV_RXLEV_NCELL_DR(n) is calculated with theA_PBGT_DR window

if less than A_PBGT_DR samples are available, the average value iscalculated with the available samples and the averaging window is filled inwith -110 dBm

2.3 Call setup

Forced Directed Retry: cause 20


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Pre-ranking using PREF_LAYER, PRIORITY(0,n), frequency band

Filtering process AV_RXLEV_NCELL_DR(n) > RXLEVmin(n) + max(0,MS_TXPWR_MAX(n) - P)

Number of free TCHs t(n) > FREElevel_DR(n)

The remaining cells are sorted according to their PBGT_DR(n)(averaging windowA_PBGT_DR)

PBGT_DR(n) = AV_RXLEV_NCELL_DR(n) - AV_RXLEV_PBGT_DR

- (BS_TXPWR_MAX- BS_TXPWR)

- (MS_TXPWR_MAX(n) -MS_TXPWR_MAX)

2.3 Call setup

FDR: Candidate cell evaluation


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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 theneighboring 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)

A_PBGT_DR: average window

Default value = 4 SACCHs

2.3 Call setup

FDR: parameters


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Thanks to idle mode parameters, Access to one preferred cell

Micro / Indoor layer: layer with very good QoS

For a better capacity increase and to avoid QoS degradation that may beinduced by an increase in HO attempts

Prevention of congestion in the preferred cell Forced Directed Retry to the old cells

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

2.3 Call setup

Access strategy


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2.3 Call Setup

Exercise

Timeallowed:

10 minutes

A dual layer network is considered

Umbrella cells 900

Micro cells 900

Set FDR parameters to avoid interference and allow apowerful TCH resource usage

Umbrella cells

microcells

FDRcapture


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Maximizing capacity

Intelligent MS sharing between available resources

Avoid congestion of historical band (for old MS)

Consider traffic conditions of all layers

Consider MS speed for layer discrimination

Keep mobiles in the same layer as long as possible


Objectives (1/2)


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Assuring 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


Objectives (2/2)


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Functional Entities

Radio

Link

Measurements

Active

Channel

Pre-processing

Assignment of HO functions in the ALCATEL BSSAssignment of HO functions in the ALCATEL BSSAssignment of HO functions in the ALCATEL BSSAssignment of HO functions in the ALCATEL BSS

BTS BSC

HO Detection HO Candidate

Cell Evaluation

HO

management

MSC

HO

protocol


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HO causes for standard networks

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


Handover causes (1/2)


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HO causes for multi-layer networks

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 highthreshold

cause 14 : high level in the neighboring cell of a lower or indoor layer forslow mobile

cause 24 : general capture


Handover causes (2/2)


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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 band

cause 14 : high level in neighboring cell of a lower or an indoor layer cell for slowmobile

cause 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


Handover causes priority


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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 cell type / band / layer / zone

Towards any cell except the serving one


Emergency Intercell Handovers


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CAUSE 2: too low quality on the uplink

AV_RXQUAL_UL_HO >L_RXQUAL_UL_H + OFFSET_RXQUAL_FH

and AV_RXLEV_UL_HO


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CAUSE 3: too low level on the uplink

AV_RXQUAL_UL_HO


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Handover Cause 4: DL Quality

CAUSE 4: too low quality on the downlink

AV_RXQUAL_DL_HO > L_RXQUAL_DL_H + OFFSET_RXQUAL_FH

and AV_RXLEV_DL_HO


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Handover Cause 5: DL Level

QUAL

LEV

CAUSE 5: too low level on the downlink

AV_RXQUAL_UL_HO


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Handover Cause 6: Distance

CAUSE 6 : Too long distance

AV_RANGE_HO >U_TIME_ADVANCE

and EN_DIST_HO = ENABLED

Size of window for distance average:A_RANGE_HO

This cause is used when a dominant cell provides a lot of scattered coverages inside other cells, due to

propagation conditions of the operational network. These spurious coverages is the probable production of ahigh level of co-channel interference.

This cause is different from the others as it is more preventive. It does not make use of the propagationconditions of a call. It just does not allow an MS to talk to a BTS if it is too far away.

It may happen for example that some peculiar propagation conditions exist at one point in time that provideexceptional quality and level although the serving BTS is far and another is closer and should be the one themobile should be connected to if the conditions were normal.

It may then happen that these exceptional conditions suddenly drop and the link is lost, which would nothave happened if the mobile had been connected to the closest cell. For these reasons also, this cause doesnot wait for the power control to react.


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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 cell type / band / layer / zone

Towards the same cell


Emergency Intracell Handovers


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CAUSE 15: High interference on the uplink

Intra-cell 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 connectionfailed

or EN_INTRACELL_REPEATED = ENABLED ]

Size of window for averaging quality:A_QUAL_HO

Size of window for averaging level:A_LEV_HO


Handover Cause 15: UL Interference

THR_RXQUAL_CAUSE_15 and EN_CAUSE_15 are not parameters but variables defined just after.


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CAUSE 16: High interference on the downlink

Intra-cell HO

AV_RXQUAL_DL_HO > THR_RXQUAL_CAUSE_16 +OFFSET_RXQUAL_FH

and AV_RXLEV_DL_HO >RXLEV_DL_IH


and [ no previous intracell handover for this connectionfailed

or EN_INTRACELL_REPEATED = ENABLED ]

Size of window for averaging quality:A_QUAL_HO

Size of window for averaging level:A_LEV_HO


Handover Cause 16: DL Interference

THR_RXQUAL_CAUSE_16 and EN_CAUSE_16 are not parameters but variables defined after.


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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

HOP

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_XXfor a non-AMR call

EN_INTRA_XX_AMR for an AMR call

XX = UL or DL

For a non AMR call, the thresholds used are identical to the ones used for CAUSE 2 and CAUSE 4.

In this case and if EN_INTRACELL_REPEATED = DISABLED, when a HO CAUSE 15 (or 16) fails, it can bemodified as UPLINK (or DOWLINK) QUALITY, HO CAUSE 2 (respectively HO CAUSE 4).


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CAUSE 12: Power budget

Normal handover type, no matter of emergency

Checked between

Cells of the same layer only

Specific case of Fast MSs: after detection of cause 12 in the lower or indoor layer,they can execute cause 12 HO towards the upper layer

Cells may be of different cell_band_type, depending on parameterEN_MULTIBAND_PBGT_HO

if EN_MULTIBAND_PBGT_HO = DISABLED and if the MS is located in the innerzone of a multi-band cell, it can only go to another multi-band cell


Handover Cause 12: Power Budget (1/5)


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CAUSE 12:

Based on Power budget equation

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)

Size of window for level averaging:A_PBGT_HO



The value of PBGT(n) is calculated every SACCH period for each neighboring cell n whose measures are kept

in the book-keeping list


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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))

else PBGT(n) >HO _MARGIN(0,n) + OFFSET_HO_MARGIN_INNER

and AV_RXLEV_PBGT_HO RXLEV_LIMIT_PBGT_HO

and EN_PBGT_HO = ENABLED

Size of window for level averaging:A_PBGT_HO



Cause 12 HO is correlated with cause 23 HO. This is why there are two equations according to the

activation of cause 23 HO (EN_TRAFFIC_HO).


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DELTA_HO_MARGIN(0,n): evaluated according to the traffic situation of theserving cell and the neighboring cell n (Traffic_load(n)) in the following way:

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

ElseDELTA_HO_MARGIN(0,n) = 0

Philosophy

This mechanism aims at penalizing cause 12 detection when the traffic in theserving cell is low and is high in the cell n.



HIGH LOW


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CAUSE 12: Power budget Traffic_load() is managed for every cell of a BSC

Traffic_load() can have three values: HIGH: cell is loaded

LOW: cell is unloaded

INDEFINITE: cell load is neither loaded nor unloaded, or unknown

The traffic_load() value is modified according to the long term traffic evaluationalgorithm using the following parameters:

A_TRAFFIC_LOAD, N_TRAFFIC_LOAD, HIGH_TRAFFIC_LOAD,IND_TRAFFIC_LOAD, LOW_TRAFFIC_LOAD: can be modified per cell

TCH_INFO_PERIOD: cannot be modified (5 s)



Annex 1

TCH_INFO_PERIOD = 5 s period used by the BSC to count the number of free TCH.


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HO_MARGIN(0,n)

A high value is usually used to avoid ping-pong HO in urban environment

where signal strength varies rapidly due to fading Default value: site dependent (but 10 dB observed for dense urban microcellular

area)

To be optimized: can be reduced to 5dB and even 0 dB when applying an anti ping-pong mechanism

A_PBGT_HO

To find a compromise with HO_MARGIN(0,n)

Default value: 8 SACCHs for urban microcells, 6 for dense urban


Cause 12: tuning of microcells parameters


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HO_MARGIN(0,n) optimization

Not triggering too many HOs

(ping-pong)

Not triggering HO to a bad target cell (for example, theperpendicular cell at a crossroads)

Not favoring emergency HO (towards theumbrella cell) with respect to power budget HObetween 2 micro cells (for example when turning

at a street corner)


Cause 12: tuning of microcells parameters

Micro 1Micro 2

Micro 3

PBGT HO between micro cells 1,2


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Speed discrimination process in micro cells:

speed estimation based on the connection time in the cell

speed is estimated from the last handover from another microcell

if this connect time is below MIN_CONNECT_TIME, MS_SPEED is set to FAST.Consequently the MS will be sent to an unloaded umbrella cell.

C_DWELL is a counter measuring the number of SACCH periods of monitoringserving micro cell

if the call has been established after an intra-BSC handover from another micro cellthen C_DWELL is compared to the threshold 2*MIN_CONNECT_TIME in order todetermine MS speed

if C_DWELL < 2*MIN_CONNECT_TIME then MS_SPEED is set to FAST

MIN_CONNECT_TIME is not modified according to the load of the micro orumbrella cells


Cause 12: speed discrimination in microcells (2/2)

Initialization of C_DWELL in serving micro cells

after call setup or incoming inter-cell handover

C_DWELL = 0

after intra-cell handover

C_DWELL is unchanged


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Handover Cause 23: Traffic (1/2)

CAUSE 23: Traffic Handover

The aim of this cause is to speed HO detection when

The serving cell is loaded

The target cell is unloaded

When traffic distribution is taken into account for handover detection, this

cause reacts in the opposite way of cause 12, to maintain an equivalent

ping-pong static hysteresis

Checked between

Cells of the same layer only

If EN_MULTIBAND_PBGT_HO = disabled

Cells of the same cell_band_type only if the MS is located in the inner zone of a multi-band cell, it can only go to

another multi-band cell

Else any other cells whatever their cell_band_type

HIGH LOW

In some multi-band networks, the radio coverage is ensured by DCS cells in one geographical area and by

GSM cells in another geographical area. As these cells form a multi-band and mono-layer network, thecapture handovers between cells of different bands will be inefficient to regulate the CS traffic load in theserving cell neighboringhood.

The solution consists in allowing intra-layer traffic handovers (Cause 23) based on a power budgetevaluation between cells of different bands.


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Handover Cause 23: Traffic (2/2)

CAUSE 23: Traffic Handover

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

Size of window for level average:A_PBGT_HO

The principle of this handover is to reduce the size of the serving cell when it is high loaded relatively to a low

loaded cell.When the mobile moves away from the BTS, the power budget will increase and a better cell handover willbe triggered earlier.

It is recommended to inhibit Traffic handover towards 1 TRX cells. These cells do not have enough resourcesto receive incoming handovers due to congestion of neighboring cells. Moreover because of the greatvariation of traffic in the 1 TRX cells, traffic load is never considered as low.

This cause is inhibited for handover from SDCCH to SDCCH.

Cause 23 is checked over all the neighboring cells belonging to the same layer. It means that it is checkedbetween cells whose CELL_LAYER_TYPE is single or upper, between cells whose CELL_LAYER_TYPE is lower,and between cells whose CELL_LAYER_TYPE is indoor.

In addition to the condition on the cell layer type, the cell frequency band condition for checking Cause 23 isas follows whether or not the MS is in the inner zone of a multi-band cell:

a) The MS is not in the inner zone of a multi-band cell

If the flag EN_MULTI-BAND_PBGT_HO is set to disabled, Cause 23 must not be checkedbetween cells which use different frequency bands (i.e cells having different CELL_BAND_TYPE).

If the flag EN_MULTI-BAND_PBGT_HO is set to enabled, Cause 23 will be checked over all theneighboring cells without any cell frequency band restriction.

b) The MS is in the inner zone of a multi-band cell

If the flag EN_MULTI-BAND_PBGT_HO is set to disabled, Cause 23 is checked over all theneighboring cell multi-band cells (FREQUENCY_RANGE= PGSM-DCS1800 or EGSM-DCS1800)which belong to the same BSC as the serving cell.

If the flag EN_MULTI-BAND_PBGT_HO is set to enabled, Cause 23 will be checked over all theneighboring cells without any cell frequency band restriction.


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Handover Cause 28: Fast Traffic HO (1/3)

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


HO

New call attempt Most appropriate MSto be pushed out

Congested cell

New call attempt

HO

Most appropriate MSto be pushed out

Upper Layer Cell


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CAUSE 28: Fast Traffic Handover

Cause 28 is only checked if the channel of the candidate MS can support thechannel 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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CAUSE 28: Fast Traffic Handover equation

AV_RXLEV_NCELL(n) > L_RXLEV_NCELL_DR(n) +max (0, [MS_TXPWR_MAX(n) - P])

and t(n) >FREELEVEL_DR(n)


and EN_FAST_TRAFFIC_HO = ENABLED

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

HO cause 28 process:

If EN_FAST_TRAFFIC_HO = enabled, when an assignment request (or external emergency HOrequest) is queued, the RAM process sends to the HOP process a Fast Traffic HO request whichcontains the queued request reference and its channel rate.

Then, HO cause 28 becomes checkable (EN_CAUSE_28=enabled).

Once an HO alarm for cause 28 is triggered, the flag EN_CAUSE_28 is set to disabled so as not toperform more than one handover. In the same time, the HOP process gets back to the RAM process aFast Traffic HO Acknowledge which contains the queued request reference and the reference of theMS that can perform HO.

If several answers are sent to the RAM process, only the first one corresponding to the queued requestis taken into account.

The RAM process checks if the request is still queued. If it is so, RAM asks HOP to start HO for thismobile; otherwise the process is stopped.

Once the HOP process receives this message, the first two conditions of Cause 28 (good enoughlevel, enough free resources in the target cell) are checked one more time. If the conditions arefulfilled, the HOP process sends an alarm to the HOM entity and the timer T_FILTER is started;otherwise the process is stopped.

Note: the first two conditions of cause 28 are tested twice in order to be sure that the candidate cells are stillvalid when the cause 28 start HO message is received from the RAM process.


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Is cause 12 triggered?


Exercise (2/2)

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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An MS is located in a lower or an indoor layer of a hierarchical network

A problem is detected on the radio link between the MS and the BTS, thisproblem is reported with an alarm cause:

Identical to standard networks

cause UL or DL quality (cause 2 and 4)

cause UL or DL Level - Low threshold (cause 3 and 5)

cause Distance (cause 6)

Specific to microcells or indoor cells

cause UL or DL for Microcell - High threshold (cause 17 and 18)

cause consecutive bad SACCH frames (cause 7)


Emergency handovers: introduction (1/2)


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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 neighboringmini cells


Emergency handovers: introduction (2/2)

in

umbrella

mini

umbrella

mini

single


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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 highthreshold

cause 18 : too low level on the downlink in a microcell compared to a highthreshold

May be triggered

From microcells only (cell_dimension_type = micro)

Outdoor microcell (micro layer)

Indoor microcell (indoor layer)


If the MS is connected to the inner zone of a multi-band cell, the serving cell isa candidate


Emergency Handovers specific to microcells


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CAUSE 7: consecutive bad SACCH frames received in a microcell

Last N_BAD_SACCH frames received are not correct

and EN_MCHO_RESCUE = ENABLED

N_BAD_SACCH

Default value: 4 SACCHs

Rule:N_BAD_SACCH >RADIOLINK_TIMEOUT_BS -N_BSTXPWR_M

to be sure that Radio Link Recovery in the microcell will be triggered before trying tomake a handover towards the umbrella

RADIOLINK_TIMEOUT_BS = 18 SACCH

N_BSTPWR_M = 15 SACCH


Cause 7: consecutive bad SACCH frames received in a microcell


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CAUSE 17: too low level on the UL in a microcell compared to a highthreshold

AV_RXLEV_UL_MCHO(i) U_RXLEV_UL_MCHO

and EN_MCHO_H_UL = ENABLED

Averaging window:A_LEV_MCHO


Cause 17: too low level on the UL in a cell compared to high thr.


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CAUSE 18: too low level on the DL in a microcell compared to a highthreshold

AV_RXLEV_DL_MCHO(i) U_RXLEV_DL_MCHO

and EN_MCHO_H_DL = ENABLED

Averaging window:A_LEV_MCHO


Cause 18: too low level on the DL in a cell compared to high thr.


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High threshold (U_RXLEV_XX_MCHO)

the HO is triggered when the signal drops under the threshold

the corresponding HO causes consist in comparing, at 2 successive SACCH periods, the DL

and UL levels in the serving microcell with a high threshold

Beginning a call under the threshold does not trigger an HO


Cause 17 & 18: comparison to high threshold (1/4)

ii-1

t

AV_RXLEV_XX_MCHO

High

Threshold

HO alarm

ii-1

t

AV_RXLEV_XX_MCHO

High

Threshold

no HO alarm


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High threshold (U_RXLEV_XX_MCHO)

With high value, mobiles will be sent too early to the macro layer

With low value, mobiles turning at a street corner will be maintained in the

microcell layer during a longer period

In theory, there is risk of call drop

In practice, with appropriate parameters,

-A PBGT HO should be triggered before (speed < 40 km/h)

- Low Threshold for safety

Problems of indoor mobiles with a signal strength level close to the high threshold

that should be kept as long as possible in the micro-layer




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U_RXLEV_XX_MCHO compared to L_RXLEV_XX_H

typical gap taken: 2dB

for DL:

L_RXLEV_DL_H = -93 dBm

U_RXLEV_DL_MCHO = -91 dBm

for UL:

L_RXLEV_UL_H = -95 (M2M), -98 (M4M), -102 (Evolium) dBm

U_RXLEV_UL_MCHO = -93 (M2M), -96 (M4M), -100 (Evolium) dBm




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A_LEV_MCHO

The averaging window size shouldnt be too small in order to:

avoid triggering too easily an HO on fading and overloading needlessly the macrocell

favor as much as possible between 2 micro cells PBGT HO

Typical value: 10 SACCHs

The high threshold is used to modelize a slow decrease of the signal level at microcellborder

Really urgent handovers will be triggered using the Low Threshold (cause 3 & 5) with ashort averaging window size

A_LEV_HO

Default value: 6 SACCHs for urban micro cells, 4 for dense urban ones




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CAUSE 14: high level in a neighboring cell of a lower or an indoor layer for slowmobiles

in order to keep dual band MSs in the preferred band, cause 14 is not checked in thefollowing cases, when EN_BI-BAND_MS(n) = DISABLED

The same scheme can be drawn between lower and indoor layers


Cause 14: high level in a lower or an indoor layer for slow MSs (2/4)

CELL_BAND_TYPE = Preferred_band

CELL_LAYER_TYPE =

upper

CELL_LAYER_TYPE =

lower or indoor

EN_BI-BAND_MS = DISABLED

CELL_BAND_TYPE = CELL_BAND_TYPE(0)


CELL_BAND_TYPE Preferred_band

CELL_BAND_TYPE = Preferred_bandCELL_BAND_TYPE Preferred_band


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CAUSE 14: high level in a neighboring cell of a lower or an indoor layer forslow mobiles

If cell_layer_type (0) = upper

AV_RXLEV_NCELL(n) > L_RXLEV_CPT_HO(0,n)

and MS_SPEED = SLOW

and EN_MCHO_NCELL = ENABLED

Averaging window:A_PBGT_HO

Anti ping-pong: not checked if T_INHIBIT_CPT is running



mini

umbrella

micro indoor


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CAUSE 14: high level in a neighboring cell of a lower or an indoor layer forslow mobiles

If cell_layer_type (0) = lower

AV_RXLEV_NCELL(n) > L_RXLEV_CPT_HO(0,n)

and MS_SPEED FAST

and EN_MCHO_NCELL = ENABLED

Averaging window:A_PBGT_HO

Anti ping-pong: not checked if T_INHIBIT_CPT is running



mini micro

indoor


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Speed discrimination objectives

maximize capacity (maximum traffic in microcells)

while optimizing quality (minimize the number of handovers)

Smart speed discrimination:

The higher the load in the umbrella cell, the higher the speed of MSs can be beforebeing directed to microcells

- to maximize capacity

- to maximize quality (avoid multiple handovers) when the load is low

Fast moving mobiles are directed to umbrella cells

a fast moving MS connected to a microcell or an indoor cell is directed to anunloaded umbrella cell (see previous part)


Cause 14: speed discrimination (1/6)


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Interlayer HO based on speed discrimination



Lower layer

Upper layer

Indoor layer

Cause12MS_speed = FAST

Cause12MS_speed = FAST

Cause14MS_speed = SLOW

Or INDEFINITE

Cause14MS_speed = SLOW


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Speed discrimination process in umbrella cells speed estimation based on the dwell time in the neighboring micro cells

if this dwell time exceeds MIN_DWELL_TIME, the MS is slow and is sent to themicrocell

C_DWELL(n) is a counter measuring the number of SACCH periods of monitoringneighboring cell n over the threshold L_RXLEV_CPT_HO(0,n)

C_DWELL(n) is compared to the threshold 2*MIN_DWELL_TIME in order todetermine MS speed

- MIN_DWELL_TIME is a variable linked to the load of the serving umbrella cell)

if for one neighboring cell n, C_DWELL(n) >= 2*MIN_DWELL_TIME then MS_SPEEDis set to SLOW




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Initialization of C_DWELL(n) in serving umbrella cells:

for all neighboring cells n of a lower layer

if EN_SPEED_DISC = ENABLED

- C_DWELL(n) = 0

else if EN_SPEED_DISC = DISABLED

- C_DWELL(n) = (MIN_DWELL_TIME -L_MIN_DWELL_TIME)*2

Consequences

if EN_SPEED_DISC = DISABLED

MSs will handover to the lower layer after L_MIN_DWELL_TIME seconds

if EN_SPEED_DISC = ENABLED

MSs will have to receive sufficient level from a lower layer cell duringMIN_DWELL_TIME seconds before leaving the upper layer




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Example with default values

Initial values

MIN_DWELL_TIME = H_MIN_DWELL_TIME = 20s

L_MIN_DWELL_TIME = 8s

C_DWELL(n) = (MIN_DWELL_TIME -L_MIN_DWELL_TIME)*2

C_DWELL(n) = ( 2 - 8 )*2

C_DWELL(n) = 12*2s

Algorithm

MS is deemed as slow if C_DWELL(n) > MIN_DWELL_TIME



0 2 4 6 8 10 12 14 16 18 20 22

: EN_SPEED_DISC = Disable

: EN_SPEED_DISC = Enable

INDEFINITE or FAST SLOW

Maximum time to reach

MIN_DWELL_TIME

=

L_MIN_DWELL_TIME

C_DWELL MIN_DWELL_TIMEC_DWELL


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Traffic regulation through the variation of MIN_DWELL_TIME

Parameters: L_MIN_DWELL_TIME, DWELL_TIME_STEP,

H_MIN_DWELL_TIME, H_LOAD_OBJ, L_LOAD_OBJ



100%

Load in theumbrella Cell

H_LOAD_OBJ

L_LOAD_OBJ

L_MIN_DWELL_TIME10 seconds

DWELL_TIME_STEP5 seconds

H_MIN_DWELL_TIME40 seconds

end: low traffic

start: low traffi

Regulation of

traffic peak

Default values

dependent on

the number of

TRXs

Default values: 8 seconds 2 seconds 20 seconds

MIN_DWELL_TIME

The initial value of MIN_DWELL_TIME is the H_MIN_DWELL_TIME parameter value.


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CAUSE 24: general capture

new capture handover

Introduced in B6.2

Improved in B7 (anti ping-pong)

May be triggered

From all cells


Can be used to capture traffic by any cell, whatever its type, band, etc.


Cause 24: general capture (1/3)


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in order to keep dual band MS in the preferred band, cause 24 is not checked

in the following cases, when EN_BI-BAND_MS(n) = DISABLED



CELL_BAND_TYPE = Preferred_band


CELL_BAND_TYPE = CELL_BAND_TYPE(0)


CELL_BAND_TYPE Preferred_band


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AV_RXLEV_NCELL(n) > L_RXLEV_CPT_HO(0,n) +max (0, [MS_TXPWR_MAX(n) - P])

and Traffic_load(0) =CAPTURE_TRAFFIC_CONDITION

and Traffic_load(n) HIGH

and EN_GENERAL_CAPTURE_HO = ENABLED

Size of window for averaging level:A_PBGT_HO

CAPTURE_TRAFFIC_CONDITION can take 3 values: ANY_LOAD (default),

HIGH, NOT_LOW Anti ping-pong: not checked if T_INHIBIT_CPT is running




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Use of cause 21 or 14?

Considering the following network

Which cause has to be used for capture? 14 or 21?

Highlight one complexity linked to causes 14 and

21 interworking when using traffic discrimination


Exercises (1/3)

900

mini1800

Timeallowed:

5 minutes

CAUSE 21: high level in the neighboring cell in the preferred band

AV_RXLEV_NCELL(n) > L_RXLEV_CPT_HO(0,n) +max (0, [MS_TXPWR_MAX(n) - P])

and Traffic_load(0) =MULTI-BAND_TRAFFIC_CONDITION

and Traffic_load(n) HIGH

and EN_PREFERRED_BAND_HO = ENABLED

Size of window for average level:A_PBGT_HO

MULTI-BAND_TRAFFIC_CONDITION can take 3 values: ANY_LOAD (default), HIGH, NOT_LOW


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Exercises (3/3)

Timeallowed:

5 minutes

Speed discrimination

What is the role of parameter EN_SPEED_DISC?

If EN_SPEED_DISC is disabled, can fast MSs bedirected toward microcells?

What is the difference between EN_SPEED_DISC =DISABLED and EN_SPEED_DISC = ENABLED whenL_LOAD_OBJ = 0% and H_LOAD_OBJ = 100%?


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As soon as an intercell HO alarm has been detected

HO Detection sends to Candidate Cell Evaluation

the HO cause value

the preferred layer for the target cell indicated by the variable PREF_LAYER (it

depends on the cell network architecture and on the operator strategy)

the list of potential candidates (it depends on type of handover cause)


From HO Detection to Candidate Cell Evaluation

CandidateCell

Evaluation

Handover

Detection

Raw cell list

cell 1: cause C1cell 2: cause C2

cell 3: cause C3

Max 32 cells

PREF_LAYER


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Standard cell environment

CELL_LAYER_TYPE = SINGLE

Better condition HO cause

Emergency HO cause

* if the MS is in the DCS 1800 inner zone of a multi-band cell then it includes the serving

cell


Raw Cell List and PREF_LAYER (2/4)

upper + singlePREF_LAYER

subset of cells verifying the HO causesRaw cell list


all neighboring cells*Raw cell list


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Hierarchical cell environment

CELL_LAYER_TYPE = UPPER


Emergency HO cause

* if the MS is in the DCS 1800 inner zone of a multi-band cell then it includes the serving

cell



nonePREF_LAYER

subset of cells verifying the HO causesRaw cell list


all neighboring cells*Raw cell list


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CELL_LAYER_TYPE = LOWER or INDOOR


Emergency HO cause

* if the MS is in the DCS 1800 inner zone of a multi-band cell then it includes the serving cell



noneLower + indoorUpper + SinglePREF_LAYER

All neighboring cells* exceptumbrella cells which do notverify AV_Rxlev_Ncell(n) >

OUTDOOR_UMB_LEV(0,n)





Raw cell list

EN_RESCUE_UM = indefiniteEN_RESCUE_UM = DISABLEDEN_RESCUE_UM = ENABLED

noneUpperPREF_LAYER

Subset of cells verifying the HOcauses

Subset of cells verifying the HOcauses plus all neighboring

umbrella cells withTraffic_Load(n) = LOW

Raw cell list

MS_SPEED FAST or

HO Cause 12

MS_SPEED = FAST and

There is a cell in the listbecause of cause 12


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Emergency handovers from lower or indoor layers

behavior depends on EN_RESCUE_UM

Normal parameter settings for minicells

EN_RESCUE_UM = DISABLED

thus PREF_LAYER = lower

Emergency handovers are preferably sent to neighboring minicells

Normal parameter settings for microcells

EN_RESCUE_UM = ENABLED

thus PREF_LAYER = upper + single

Emergency handovers are preferably sent to umbrella cells or neighboring

macrocells




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Evaluation process

Measurement

Preprocessing

A_LEV_HO

A_QUAL_HO

A_PBGT_HO

A_RANGE_HO

HO Detection

Cause 2: uplink quality

Cause 3: uplink level

Cause 4: downlink quality

Cause 5: downlink level

Cause 6: distanceCause 12: power budget

Performed every SACCHPerformed every SACCH

Pre-ranking

Priority (0, n) = 0

Cell 2: cause C2

Cell 3: cause C2

Cell 4: cause C2

Priority (0, n) = 1

Cell 1: cause C2

Priority (0, n) = 2Priority (0, n) = 3

Cell 5: cause C2

Cell 6: cause C2

Cell 7: cause C2

Cell 8: cause C2

Priority (0, n) = 4

Priority (0, n) = 5

Priority (0, n) = 0

Cell 2: cause C2

Cell 3: cause C2

Cell 4: cause C2

Priority (0, n) = 1

Priority (0, n) = 2

Priority (0, n) = 3

Cell 6: cause C2

Cell 8: cause C2

Priority (0, n) = 4

Priority (0, n) = 5

PBGT filteringHO_MARGIN_XX(0,n)

Grade

Priority (0, n) = 0

Cell 4: cause C2

Cell 2: cause C2

Cell 3: cause C2


Priority (0, n) = 3

Cell 6: cause C2

Cell 8: cause C2

Priority (0, n) = 4

Priority (0, n) = 5

Order

Priority (0, n) = 0

Cell 4: cause C2

Cell 3: cause C2

Cell 2: cause C2


Priority (0, n) = 3

Cell 6: cause C2

Cell 8: cause C2

Priority (0, n) = 4

Priority (0, n) = 5

Cell evaluation process (Order or Grade)

HO Candidate Cells Evaluation

Max

every SACCH

Preprocessmeasurement

Measurementresult

Raw cell list

Cell 1: cause C2

Cell 2: cause C2

Cell 3: cause C2

Cell 4: cause C2Cell 5: cause C2

Cell 6: cause C2

Cell 7: cause C2

Cell 8: cause C2

... max 32 cells

The HO candidate evaluation process is run after all intercell handover alarms.

In case of intra-cell handover alarm (HO causes 10, 11, 13, 15, 16), the candidate cell evaluation process isskipped: the target cell is the serving cell.

The handover detection gives as indication the raw cell list (built from the book-keeping list) and thepreferred layer for the handover.In case of emergency handover alarms or cause 20 alarm, the cellevaluation will order the cells given in the raw list, putting in the first position the cells belonging to thepreferred layer, having the highest priority (if EN_PRIORITY_ORDERING=ENABLED) and/or having the samefrequency band type as the serving cell. In case of an intercell handover alarm, if the serving cell belongs tothe raw cell list (emergency handover from the DCS 1800 inner zone of a multi-band cell), this cell is put atthe end of the candidate cell list with the MS zone indication OUTER.

In case of better condition handover alarms (except cause 20), the cell evaluation will order the cells given inthe raw list, putting in the first position the cells belonging to the preferred layer and having the highest

priority (if EN_PRIORITY_ORDERING=ENABLED).


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Pre-ranking in standard networks

with PRIORITY(0,n) settings, the operator can

for each couple of cells

tag the target cell with a defined priority (from 0 = max to 5 = min)

this definition has a higher priority than usual order/grade ranking

especially useful for multi band/hierarchical architectures

a simple way to force a target cell whatever its RxLev and PBGT

nevertheless it can be skipped over by filtering processes

low interest for standard networks

Serving cell

Candidate cell 1: RxLev: - 70 dBm, pbgt: + 10 dB

Candidate cell 2: Rxlev: - 90 dBm, PBGT: + 5dB

P0

P1

PRIORITY(0,n) can take 6 different values since B7, to take into account new indoor layers.


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In hierarchical or multi-band networks, pre-ranking is used

For emergency handovers + Forced Directed Retry

Cell_layer_type: single, upper, lower, indoor

PRIORITY(0,n): 0 to 5

Cell_band_type: GSM or DCS

For better condition handovers

Cell_layer_type: single, upper, lower, indoor

PRIORITY(0,n): 0 to 5

PRIORITY(0,n) are taken into account only ifEN_PRIORITY_ORDERING isset to enabled on the serving cell


Pre-ranking in complex networks (1/3)


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Pre-ranking in case of emergency HO, plus cause 20 and 28 :



Cell_layer_type = Pref_layer

Cell_layer_type Pref_layer

List of candidate cells n

Cell_band_type = serving cell

Cell_band_type serving cell

Priority(0,n) = 0

Priority(0,n) = 1

Priority(0,n) = 5

Priority(0,n) = 0

Priority(0,n) = 1

Priority(0,n) = 5


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Pre-ranking in case of better condition HO:



Cell_layer_type = Pref_layer

Cell_layer_type Pref_layer

List of candidate cells n

Priority(0,n) = 0

Priority(0,n) = 1

Priority(0,n) = 5

Priority(0,n) = 0

Priority(0,n) = 1

Priority(0,n) = 5


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PBGT Filtering

PBGT filtering: process introduced since B5 optional, activated through the flag EN_PBGT_FILTERING

filter out cells from the target list inhibited for better conditions handovers

based on power budget

Mandatory for multi-band networks

PBGT(n) > HO_MARGIN_XX (0,n) + OFFSET_HO_MARGIN_INNER

HO_MARGIN_XX (0,n) = HO_MARGIN_QUAL (0,n) for causes 2, 4, 7

HO_MARGIN_XX (0,n) = HO_MARGIN_LEV (0,n) for causes 3, 5, 17, 18, 28

HO_MARGIN_XX (0,n) = HO_MARGIN_DIST (0,n) for cause 6

OFFSET_HO_MARGIN_INNER is only applied when the MS is in the inner zone of aconcentric or multi band cell

The average window is A_PBGT_HO

The filtering process allows to filter out cells from the target list before sending them to the ORDER or GRADE

evaluation process.It can be enabled/disabled on-line on a per cell basis from the OMC-R with the flag EN_PBGT_FILTERING.

The candidate cells are filtered on their power budget in relation to a handover margin threshold based onthe handover cause.

Note: the average window used for this process is A_PBGT_HO (even for emergency handovers, wherehandover alarm could have been raised through A_LEV_HO or A_QUAL_HO samples).

Warning: HO_MARGIN_xx (LEV, DIST or QUAL) has nothing to do with a handover margin value, specific forcertain handover causes (anyway, these handovers cause only tackle source cell and are not looking at levelof targets for handover detection).

HO_MARGIN is used for handover detection (cause 12 or 23).

HO_MARGIN_xx are used for candidate cell evaluation.

Thus, there is no having HO_MARGIN = HO_MARGIN_xx! Let us see three examples:1) If HO_MARGIN_xx = HO_MARGIN = 5 dB

In that case, when an emergency handover is triggered (level, quality, distance, etc.), all neighboring cellsare filtered regarding their PBGT compared to 5 dB! By the way, if a cell that is not greater than theserving one + 5 dB will be filtered out: this handover, detected as an emergency case, is in fact abetter cell one.

2) If HO_MARGIN_xx is very small (for example, -30 dB),

multi layer

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