Common BCCH

Common BCCH Control

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# Nokia Siemens Networks 1 (105)

BSC3153Nokia GSM/EDGE BSS, Rel. BSS13, BSC andTCSM, Rel. S13, Product Documentation, v.1

The information in this document is subject to change without notice and describes only theproduct defined in the introduction of this documentation. This documentation is intended for theuse of Nokia Siemens Networks customers only for the purposes of the agreement under whichthe document is submitted, and no part of it may be used, reproduced, modified or transmitted inany form or means without the prior written permission of Nokia Siemens Networks. Thedocumentation has been prepared to be used by professional and properly trained personnel,and the customer assumes full responsibility when using it. Nokia Siemens Networks welcomescustomer comments as part of the process of continuous development and improvement of thedocumentation.

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2 (105) # Nokia Siemens Networks DN0176501Issue 8-0 en20/03/2008

Common BCCH Control

Contents

Contents 3

List of tables 5

List of figures 6

Summary of changes 7

1 Overview of Common BCCH Control 9

2 Technical description of Common BCCH Control 152.1 Common BCCH frequency bands 152.2 Mobile station capabilities with Common BCCH Control 172.3 Intra-segment resource usability estimation 192.4 Inter-segment resource usability estimation 192.5 Segment environment 20

3 System impact of Common BCCH Control 233.1 Requirements 233.2 Restrictions 253.3 Impact on transmission 273.4 Impact on BSS performance 273.5 User interface 273.6 Impact on Network Switching Subsystem (NSS) 373.7 Impact on NetAct products 373.8 Impact on mobile terminals 383.9 Impact on interfaces 393.10 Interworking with other features 39

4 Common BCCH Control system information messages 534.1 Common BCCH Control Cell Allocation 534.2 Common BCCH Control Mobile Allocation 544.3 Common BCCH Control BCCH allocation 55

5 Radio resource management and Common BCCH Control 575.1 SDCCH allocation in Common BCCH segment 575.2 TCH allocation in Common BCCH segment environment 60

6 Handover algorithm and Common BCCH Control 696.1 SDCCH resource usability evaluation in Common BCCH 696.2 TCH resource usability evaluation in Common BCCH 746.3 Extended call set-up in Common BCCH segment 816.4 SDCCH handover based on reservation duration and Common BCCH

Control 826.5 Load-based TCH handover and Common BCCH Control 836.6 Intra-segment handover from non-BCCH layer based on signal level 856.7 Power budget handover and Common BCCH Control 866.8 IUO handover and Common BCCH Control 87

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Contents

6.9 Channel allocation criteria based on the minimum acceptable C/N ratioand Common BCCH Control 88

6.10 Optimisation of the MS power level in handover and in call set-up andCommon BCCH Control 94

7 Planning Common BCCH 997.1 Common BCCH and handover 997.2 Common BCCH and channel allocation 1007.3 SDCCH dimensioning with Common BCCH 103

8 Implementing Common BCCH Control overview 105


Common BCCH Control

List of tables

Table 1. Required additional or alternative hardware or firmware 23

Table 2. Required software 24

Table 3. Impact of Common BCCH Control on BSC units 27

Table 4. Counters of Handover Measurement related to Common BCCHControl 33

Table 5. Counters of BSC Level Clear Code (PM) Measurement related toCommon BCCH Control 35

Table 6. Counters of Non-BCCH Layer Offset Measurement related to CommonBCCH Control 36

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List of tables

List of figures

Figure 1. GSM 900 / GSM 1800 Common BCCH configuration 10

Figure 2. High level view of a SEG containing three frequency bands 16

Figure 3. Segment and BTS object in Common BCCH 21Figure 4. Example of SEG radio network objects 22Figure 5. IUO frequency groups in GSM 900 / GSM 1800 Common BCCH

network 42

Figure 6. IUO frequency groups in GSM 800 / GSM 1900 Common BCCHnetwork 42

Figure 7. Possible handover directions on a segment 43

Figure 8. Hopping groups in a segment with GSM 900 and GSM 1800 resources(BCCH on PGSM 900) 44

Figure 9. Hopping groups in a segment with GSM 800 and GSM 1900 resources(BCCH on GSM 800) 45

Figure 10. Different interference levels with BSC recommendation 2 and withoutrecommendation when searching for full-rate TCHs 63

Figure 11. Intra-segment handover from non-BCCH frequency layer to BCCHfrequency layer of the segment 85

Figure 12. PBGT HO decision when non-BCCH layer has less coverage 86


Common BCCH Control

Summary of changes

Changes between document issues are cumulative. Therefore, the latestdocument issue contains all changes made to previous issues.

Changes made between issues 8-0 and 71

The name of the document has been changed from Common BCCHControl in BSC to Common BCCH Control.

Sections System impact of Common BCCH and Implementing CommonBCCH have been added.

Information related to PGSM 900 and EGSM 900 frequencies whenregarded as a single BTS objects has been removed from chaptersOverview of Common BCCH Control, System impact of Common BCCHand Common BCCH Control system information messages.

Sections Requirements for Common BCCH Control in BSC and Userinterface of Common BCCH Control in BSC have been removed.

Changes made between issues 71 and 70

Information on frequency hopping in an EGSM - PGSM BTS has beenadded in chaptersTechnical description of Common BCCH Control in BSCand Common BCCH Control system information messages.

Changes made between issues 70 and 62

In Overview of Common BCCH Control, a list of related topics has beenadded.

In Technical description of Common BCCH Control in BSC, a shortreference to Dual Transfer Mode (DTM) has been added.

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Summary of changes

In Requirements for Common BCCH Control in BSC, Nokia Flexi EDGEBTS has been added to the list software requirements for Common BCCHControl in BSC.

The figure Example of SEG radio network objects has been improved.


Common BCCH Control

1 Overview of Common BCCH ControlCommon BCCH Control allows the integration of resources from differentfrequency bands into one cell. TRXs of different frequency bands can beconfigured in the same cell by letting them share a common BCCH thathas been allocated from one frequency band used in the cell.

A common broadcast control channel (BCCH) of a cell is configured in onlyone of the bands of operation when resources across all bands are co-located and synchronised.

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Overview of Common BCCH Control

Figure 1. GSM 900 / GSM 1800 Common BCCH configuration

Common BCCH Control enhances the functionality of a cell to offer serviceto multiband user equipment in all the frequency bands which theysupport. It also provides improved trunking gain, tighter reuse of carriers,better quality because the number of handovers decreases, and improvedspectral efficiency.

///

O&M

O&M

Cell 1GSM900 (BCCH) /

GSM1800


GSM1800


GSM1800

Cell 2

Cell 1

Cell 3

BTS-900

BTS-900

BTS-900

BTS-1800

BTS-1800

BTS-1800

GSM900 GSM1800

Synch.

BSC

Abis interface


Common BCCH Control

The basic implementation of Common BCCH Control is based on thesegment concept where the different frequency bands are separate BTSobjects in the segment.

The BSC supports Common BCCH Control for Nokia Talk-family, NokiaUltraSite, Nokia Flexi EDGE, and MetroSite base stations.

Common BCCH Control is an application software in the BSC.

Benefits of Common BCCH Control

Using Common BCCH Control gives you the following benefits:

. improved trunking gain

. optimised use of signalling channels by sharing them betweenbands

. the absence of a BCCH channel (in non-BCCH frequency band)leads to a reduction of the overall interference and allows morefreedom in frequency allocation with improved quality

. reduced number of cells in the network

. reduced number of Location Area Codes (LAC)

. reduced number of neighbouring cells

. multi-layer network simplified into one-layer network

. quality improvement due to decreased number of handoversbetween frequency layers; calls directed to an appropriate layer incall set-up

Other related topics

. Test and activate. Radio network performance

. BSS10016 and BSS10118: Common BCCH Control forGSM. Activating and Testing BSS10016 and BSS10118:

Common BCCH Control for GSM

. Operate and maintain. Radio Network Administration

. Reference. Alarms

. Base Station Alarms (70007999)

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. Commands. MML commands

. EA - Adjacent Cell Handling

. EE - Base Station Controller Parameter Handlingin BSC

. EH - Handover Control Parameter Handling

. EQ - Base Transceiver Station Handling in BSC

. EU - Power Control Parameter Handling. Counters/Performance indicators

. Call Control Measurements (CS). 4 Handover Measurement. 51 BSC Level Clear Code (PM) Measurement. 92 Non-BCCH Layer Offset Measurement

. Parameters. BSS Radio Network Parameter Dictionary

. Descriptions. Functional descriptions

. Radio network performance. Radio Channel Allocation. RF Power Control and Handover Algorithm. Traffic Reason Handover in BSC

. Operability. Radio Network Supervision in BSC

. Feature descriptions. Radio network performance

. Advanced Multilayer Handling

. Direct Access to Desired Layer/Band (DADL/B)

. Directed Retry in BSC

. Dual Band Network Operation

. Enhanced Coverage by Frequency Hopping

. Enhanced Speech Codecs: AMR and EFR

. FACCH Call Set-up

. Frequency Hopping

. Intelligent Underlay-Overlay

. PGSM 900 - EGSM 900 BTS in BSC. Data

. GPRS System Feature Description

. HSCSD and 14.4 kbit/s Data Services in BSC


Common BCCH Control

. Macrocellular. Extended Cell. Handover Support for Coverage Enhancement. Multi BCF Control in BSC

. Value added services. Radio Resource Pre-emption and Queuing. Trunk Reservation

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Common BCCH Control

2 Technical description of Common BCCHControl

2.1 Common BCCH frequency bands

The following frequency band combinations are supported:

. PGSM 900 / EGSM 900

. PGSM 900 / GSM 1800

. PGSM 900 / EGSM 900 / GSM 1800

. EGSM 900 / GSM 1800

. GSM 800 / GSM 1900

The BCCH carrier is allowed in any of the supported frequency bands.

Note that if you combine the resources of several base stations into onesegment, you must have Multi BCF Control activated.

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Technical description of Common BCCH Control

Figure 2. High level view of a SEG containing three frequency bands

A common BCCH segment must contain a "serving layer". It is thefrequency band, which contains the TRX with the BCCH channel, and anyother combination of TRXs from other frequency bands.

The band where the BCCH carrier is in the common BCCH controlledsegments must be the same throughout the whole network. This ensuresthat the support for single band mobile stations remains in at least one ofthe frequency bands of operation. It is also possible that there are singleband cells, possibly on different frequency bands, in the networksimultaneously with the multiband common BCCH segments and theservice to mobile stations is offered via these single band cells as well.

The need for dividing GSM 900 resources into two different bands inCommon BCCH Control comes from the different capabilities of theterminals. Specifications state that the EGSM 900 band includes both theprimary GSM 900 frequencies and the extension band. This means thatBTSs and mobile stations supporting EGSM 900 support also the PGSM900 frequencies. In the Nokia segment solution, however, an EGSM 900BTS contains only the extended band GSM 900 frequencies that areoutside the primary GSM 900 band. Using this division the BSC can makesure that only terminals supporting EGSM 900 are directed to the EGSM900 frequencies.

In addition to the varying capabilities of terminals in supporting differentfrequency bands, the BCCH frequency band and the non-BCCHfrequency band have to be kept as separate resources because of thedifferent propagation properties of these two bands. To ensure properoperation of the network, you should take into account issues related tothe difference of propagation when performing cell planning.

BTS

SEG

GSM 1800

EGSM 900

PGSM 900


Common BCCH Control

The above discussion about the different propagation properties refers tothe resource division between GSM 900 and GSM 1800 and also betweenGSM 800 and GSM 1900. Because the division between PGSM 900 andEGSM 900 resources exists only because of the different capabilities ofthe terminals, the BSC regards these two bands as equal from the radioproperties' point of view. If, for example, the BCCH of a segment is in aPGSM 900 BTS, and there is also an EGSM 900 BTS in the segment, theresources of this latter BTS are regarded usable whenever the resourcesof the BCCH BTS are regarded usable, if only the MS in question supportsEGSM 900.

2.2 Mobile station capabilities with Common BCCHControl

In each frequency combination environment, Mobile Stations (MS) maysupport one or more of the frequency bands specified in the GSMspecifications. An MS which supports more than one frequency band andthe functionality described in the following paragraph is defined as amultiband MS [3GPP 43.026].

The multiband MS has the functionality to perform handover, channelassignment, cell selection and cell re-selection between all its bands ofoperation within a PLMN when one PLMN code is used in all bands.Additionally, it has the functionality to make a PLMN selection, in manualor automatic mode, in all its bands of operation. The multiband MS willmeet all requirements specified for each individual band. In addition, it willmeet the extra functional requirements for multi band MSs.

Selection of the frequency band in a common BCCH segment is based onthe resource situation on each band and the frequency capabilities of themobile station. The BCCH carrier is configured in the same frequencyband in the whole area of the network. Consequently, the mobile stationswhich have service in the common BCCH network can be distinguished asfollows:

Single Band MS

MS supports one frequency band.

Multi Band MS

MS supports two or more frequency bands.

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In a network where cells with resources from different frequency bands arecontrolled by a common BCCH on one of those bands, the access to thenetwork is limited to the mobile stations that support the BCCH frequencyband of the network. Thus, the MSs, single band or multiband, supportingthe BCCH frequency band have access to the services of the commonBCCH network.

MS Classmarks

Different classes of mobile stations can be defined according to theirfrequency capabilities. .The information of the mobile station's frequencycapabilities is included in two information elements (IEs):. Mobile Station Classmark 2 IE, which includes information on the

possible EGSM 900 capability of the mobile station. The networkreceives this IE in the ESTABLISH INDICATION message.

. Mobile Station Classmark 3 IE, which defines all the frequencybands supported by the MS and the MS power capabilities in eachsupported frequency band. The network receives this IE in theCLASSMARK CHANGE message.

The BSC receives both of these messages while the related mobile stationis on a dedicated signalling channel (SDCCH).Controlled early classmark sending

In early classmark sending, the MS sends a Classmark Change messageas early as possible after accessing the network to provide the additionalclassmark information. An MS which carries out the "Controlled earlyclassmark sending" option, performs the early classmark sending if thenetwork explicitly accepts it, as indicated in the last reception of theSystem Information type 3 message in the accessed cell.

An MS which carries out one of the "Multiple band support" options alsocarries out the "Controlled Early Classmark Sending" option. An MS whichcarries out the "Controlled early classmark sending" option indicates it inthe Mobile Station Classmark 2 (ES IND = Establishment Indication bit).The MS also sends the Classmark Change message containing theMobile Station Classmark 2 and Mobile Station Classmark 3 informationelements on the first occasion if the network accepts it.


Common BCCH Control

2.3 Intra-segment resource usability estimation

When the BSC has received information on both the MS frequency bandcapability and on the downlink received BCCH signal level (measurementreport), it defines the usability of the segment's different resource types.For formulas for non-BCCH layer resource usability estimation used (inintra-segment SDCCH-SDCCH handovers and TCH allocations for callset-up, or intra-segment TCH-TCH handovers), see SDCCH resourceusability evaluation in Common BCCH.

If the MS is on a BCCH layer channel, the RXLEV_DL is the terminalreceived signal level on the channel. If the MS is using a non-BCCH layerchannel, the RXLEV_DL is the downlink signal level of the BCCH carrier ofthe segment.

If the RX level based TCH access is in use, the TCH usability in call set-upand intra-segment TCH-TCH handover is determined with the followingformula:

RXLEV_DL - non BCCH layer offset >= C/N + DL noise level + 110

where carrier-to-noise ratio (C/N) is a user-defined BSC-level parameterseparate for each call type and DL noise level a user-defined BTS-levelparameter. For a list of the user-defined BSC-level C/N parameters, seeBSC radio network object parameters in BSC parameters.

2.4 Inter-segment resource usability estimation

When the BSC has defined a need for an inter-segment (SDCCH-SDCCHor TCH-TCH) handover based on the measurements of the servingchannel, the usability of the different resource types of each candidatesegment is decided using the BCCH measurement results for the segmentand the values of parameter non BCCH layer offset for different resourcetypes in the segment. For more information on the criteria used, see TCHresource usability evaluation in Common BCCH.

RxLevMinCell(n) is the level which the signal level in the adjacent segmentmust exceed for the handover to the adjacent segment to becomepossible.

If the RX level based TCH access is in use, the TCH usability in inter-segment TCH-TCH handover is determined with the following formula:

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AV_RXLEV_NCELL(n) - non BCCH layer offset >= C/N + DL noiselevel + 110

where C/N is a user-defined BSC-level parameter separate for each calltype and DL noise level a user-defined BTS-level parameter. For a list ofthe BSC-level C/N parameters, see BSC radio network object parametersin BSC Parameters.

In a handover between two BSCs, the radio link measurements related tothe target segment are available on the source side BSC only. It istherefore not possible to use the radio link measurements to define theusability of the non-BCCH layer resources on the target side. In this casethe decisions are based on the non BCCH layer offset parameter. If thenon-BCCH layer is regarded as a layer with less coverage (as indicated bythe positive value of the non BCCH layer offset parameter), only BCCHfrequency band resources are used in channel allocation for externalhandovers.

For more information, see Radio Channel Allocation under Functionaldescriptions/Radio network performance in the PDF view.

2.5 Segment environment

Multi BCF Control and Common BCCH Control use an architecture andradio network object called segment (SEG). The properties of a segmentare the following:

. A segment is essentially the same as a telecom cell.

. A segment may consist of several BTS objects.

. BTSs of a segment are co-located and synchronised.

. The maximum number of BTSs in a segment is 32.

. The maximum number of TRXs in a segment is 36.

The BTS object in a segment must consist of TRXs of the same. frequency band (PGSM 900, EGSM 900, GSM 1800, GSM 800,

GSM 1900 separated). base station site type (Talk-family, UltraSite, Flexi EDGE, and

MetroSite separated)


Common BCCH Control

Figure 3. Segment and BTS object in Common BCCH

Figure Segment and BTS object in Common BCCH shows a typical BTSconfiguration in Common BCCH. When considering Common BCCH,segment-specific and BTS-specific parameters should be taken intoaccount. In many cases the BTS and the frequency band are the same.However, sometimes they are different. For example, PGSM 900 Talk-family and PGSM 900 UltraSite must be configured as separate BTSs.Segment-specific, BTS-specific, and frequency-band-specific parametersneed to be considered in this case.

The allocation of a dedicated channel (SDCCH or TCH) inside a multibandsegment (that is, with BTSs from different frequency bands) is based on:. the frequency capabilities of the mobile station. the prevailing radio conditions of the mobile station. the resource situation on each band.

The second condition is evaluated for the secondary frequency band usingthe BTS parameter non BCCH layer offset.

BTS BTS BTS

PGSM 900

PGSM 900BCCH

EGSM900

GSM 1800

SEGMENT

Segment specificparameters

BTS specific parameters

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The possibility to use the segment structure is not restricted to Multi BCFControl or Common BCCH Control software, but it is an option of its own.You can, for example, create multiple hopping groups in a cell by gatheringTRXs of one hopping group into one BTS object and have several suchBTSs in a segment.

The common BCCH segment is seen as one single cell even thoughparameterisation and management has been partly separated betweenthe segment object and the BTSs of the segment. The MS also sees thesegment as one BCCH frequency band cell and many SEGs as oneBCCH frequency band network because it has no knowledge of the otherfrequency bands in a segment because these bands have no BCCH.

Figure 4. Example of SEG radio network objects

For an overview of Multi BCF Control, see Multi BCF Control underFeature descriptions/Macrocellular in the PDF view.

SEG-2

BCF-1

BTS-1 BTS-2

BTS-4

TRX-4 TRX-1

TRX-3BCCH

BCCH

= GSM 900

= GSM 1800

SEG-1

BTS-3

TRX-2

BCF-2


Common BCCH Control

3 System impact of Common BCCHControl

The system impacts of BSS10016: Tri-Band GSM/EDGE Common BCCH,ETSI and BSS30045: GSM/EDGE Common BCCH, ANSI are specified inthe sections below.

Common BCCH Control is an application software product.

3.1 Requirements

Hardware requirements

Table 1. Required additional or alternative hardware or firmware

Network element HW/FW required

BSC No requirements

BTS RF units are bandspecific, and correctRF units are neededfor the supportedfrequency bands.

TCSM No requirements

SGSN No requirements

Software requirements

Table Required software shows the earliest version that supports CommonBCCH Control.

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System impact of Common BCCH Control

Table 2. Required software

Network element Software releaserequired

BSC S11.5

Nokia Flexi EDGEBTSs

EP1.0

Nokia UltraSiteEDGE BTSs

CX4.0

Nokia MetroSiteEDGE BTSs

CXM4.0

Nokia Talk-familyBTSs

DF6.0

Does not support 800/1900 Common BCCH.

Nokia InSite BTSs Does not supportCommon BCCHControl.

MSC No requirements

Nokia NetAct OSS3.1 ED1(EnhancementDelivery)

NetAct Planner 4.0

SGSN No requirements

Frequency band support for Common BCCH Control

The BSC supports Common BCCH on the following frequency bands:

. GSM 800

. GSM 900

. GSM 1800

. GSM 1900


Common BCCH Control

3.2 Restrictions

The use of Common BCCH Control and the segment environment causesrestrictions for the functionality of the following application and operatingsoftware.

Configuration with Common BCCH Control

The band where the BCCH carrier is in the common BCCH controlledsegments must be the same throughout the whole network.

BCCH Allocation and Common BCCH Control

In Common BCCH, the BCCH frequency of the segment is added amongthe BCCH frequencies that the MS should measure when the MS is activeon the non-BCCH band of the segment. This leads to the followingrestrictions:

. There can be only 31 frequencies in adjacent cell and BA lists.

. Only 5 of the strongest neighbours are included in the adjacent cellmeasurements.

GSM-WCDMA Interworking and Common BCCH Control

If GSM-WCDMA Interworking and Common BCCH Control are usedtogether, the maximum amount of adjacent cells and frequencies in a BAlist is 30.

SDCCH allocation and Common BCCH Control

In a multiband Common BCCH segment, the initial SDCCH channel for acall setup is always allocated in the frequency band where also thesegment's BCCH is. Note that when the BCCH is on the EGSM 900 band,then all the GSM 900 resources of the segment can be regarded as beingof the EGSM 900 frequency band and the segment's possible PGSM 900resources are also available for the initial SDCCH allocation of a call.

When an SDCCH is allocated for an external handover in a multibandCommon BCCH segment the search may be restricted among the BCCHfrequency band resources of the segment. This depends on the frequencyband the BCCH is using. If the non-BCCH layer is regarded as a layer withless coverage (as indicated by the positive value of the non BCCH layeroffset parameter) then only BCCH frequency band resources are usedin the SDCCH allocation for an external handover.

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TCH allocation and Common BCCH Control

Since a FACCH setup takes place as a response to an SDCCH allocationrequest the same restrictions as for SDCCH allocation represented in theprevious chapter apply. In a multiband common BCCH segment the TCHfor a FACCH setup is always allocated in the BCCH frequency band of thesegment. When a segment's BCCH carrier is on EGSM 900 band then thesegment's possible PGSM 900 resources are also available for theFACCH setup.

When a TCH is allocated for an external handover in a multiband commonBCCH segment the search may be restricted among the BCCH frequencyband resources of the segment. This depends on the frequency band theBCCH is using. If the non-BCCH layer is regarded as a layer with lesscoverage (as indicated by the positive value of the non BCCH layeroffset parameter) then only BCCH frequency band resources are usedin TCH allocation for external handover.

Dynamic SDCCH allocation and Common BCCH Control

The dynamic SDCCH RTSLs can be utilised only in the BCCH frequencyband in a common BCCH cell. This is because of the fact that themultiband capabilities of an accessing MS are not known at the time of theinitial SDCCH allocation. When a segment's BCCH carrier is on EGSM900 band then the segment's possible PGSM 900 resources are alsoavailable for the dynamic SDCCH allocation.

Extended cell range and Common BCCH Control

In the segment environment, only BCCH BTS can have extended areaTRXs.

Intelligent Underlay Overlay (IUO) and Common BCCH Control

The super-reuse layer of a BTS in a segment with several BTSs can beaccessed only via the regular layer of the BTS.

The handover from super-reuse resources back to the regular layer is notrestricted totally inside source BTS. But it is limited among the segment'sBTSs that can be regarded as stronger than or equal to the source BTS(as indicated by the values of the respective non BCCH layer offsetparameters).Frequency Hopping and Common BCCH Control

The multiband MS and the multiband network support Frequency Hoppingwithin each band of operation. Frequency Hopping between the bands ofoperation is not supported.


Common BCCH Control

Cell broadcast and Common BCCH Control

You can give definitions with the ECS command only for the BCCH BTS.

3.3 Impact on transmission

No impact.

3.4 Impact on BSS performance

OMU signalling

No impact.

TRX signalling

No impact.

Impact on BSC units

Table 3. Impact of Common BCCH Control on BSC units

BSC unit Impact

MCMU No impact

BCSU No impact

PCU No impact

Impact on BTS units

No impact.

3.5 User interface

BSC MMI

The following MML programs are used for handling Common BCCHControl:

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. Adjacent Cell Handling: EA

. Base Station Controller Parameter Handling in BSC: EE

. Base Transceiver Handling in BSC: EQ

. Handover Control Parameter Handling: EH

. Power Control Parameter Handling: EU

For more information, see MML commands under Reference/Commandsin the PDF view.

BTS MMI

Common BCCH Control cannot be managed with BTS MMI.

BSC parameters

Most of the parameters related to Common BCCH Control are defined persegment object. Parameters related to Common BCCH Control inAdjacent Cell Handling, Handover Control Parameter Handling, andPower Control Parameter Handling are all defined as common values forthe BTSs of one segment. In the Base Transceiver Station Handlingcommand group most of the parameters are segment level parameters,but there are also BTS-specific parameters with the possibility to defineseparate values for different BTS objects of a segment. For the parameterdivision between BTS and segment objects in Base Transceiver StationHandling, see BSS Radio Network Parameter Dictionary. underReference/Parameters in the PDF view.

Adjacent GSM Cell (ADJC/ADCE) radio network object parameters. MS txpwr max gsm

. MS txpwr max gsm1x00

. GPRS MS txpwr max cch

. GPRS MS txpwr max cch1x00

The parameters MS txpwr max gsm (PMAX1) and MS txpwr maxgsm1x00 (PMAX2) are used regardless of whether the Common BCCHControl options are enabled or not. MS txpwr max gsm (PMAX1) is usedin the GSM 900 and the GSM 800 frequency bands, and MS txpwr maxgsm1x00 (PMAX2) is used on the GSM 1800 and the GSM 1900frequency bands.


Common BCCH Control

The parameters MS txpwr max CCH1x00 (TXP2) and GPRS MS TX pwrmax CCH1x00 (GTXP2) are used regardless of whether the CommonBCCH Control options are enabled or not. These new parameters areused in cells where the BCCH is either on the GSM 1800 or on GSM 1900frequency band. The parameters MS txpwr max CCH (TXP1) and GPRSMS TX pwr max CCH (GTXP1) are used in cells where the BCCH is eitheron the GSM 900 or GSM 800 frequency band.

Base Station Controller (BSC) radio network object parameters. intra segment SDCCH HO guard

. RX level based TCH access

. soft blocking C/N FR

. soft blocking C/N HR

. soft blocking C/N AMR FR

. soft blocking C/N AMR HR

. soft blocking C/N 14.4

The parameter intra segment SDCCH HO guard (ISS) is used forcontrolling the transfer of SDCCH reservations out of the BCCH resourcelayer in the segments under the control of the BSC.

Base Transceiver Station (BTS) radio network object parameters. BTS load in SEG

. non BCCH layer offset

. GPRS non BCCH layer rxlev lower limit

. GPRS non BCCH layer rxlev upper limit

. DL noise level

The BTS-specific parameter non BCCH layer offset (NBL) is used forestimating the signal level of the non-BCCH layer resources and BTSload in SEG (LSEG) is used for controlling the traffic load in differentBTSs of a segment.

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The parameter non BCCH layer offset (NBL) is used to indicate howmuch weaker the signal level of a BTS is when compared to that of theBCCH BTS. Because of this the value of the parameter must always be setto value 0 in the BCCH BTS. A positive value of NBL in a BTS indicates asignal level that is lower than in the BCCH BTS and prevents the SDCCHallocation for call set-ups and TCH allocation in external handovers in thatBTS.

The band-specific parameters bs tx pwr max (PMAX1) and bs tx pwrmax 1x00 (PMAX2) have an effect on setting the parameter non BCCHlayer offset (NBL).

Frequency-band-specific BTS radio network object parameters. GPRS MS txpwr max cch

. GPRS MS txpwr max cch1x00

. MS txpwr max cch

. MS txpwr max cch1x00

. MS txpwr max gsm

. MS txpwr max gsm1x00

Handover Control (HOC) radio network object parameters. non BCCH layer access threshold

. non BCCH layer exit threshold

. non BCCH layer exit threshold Px

. non BCCH layer exit threshold Nx

The parameter non BCCH layer access threshold (LAR) is used forthe usability evaluation of the weaker frequency band in a segment withresources from different frequency bands. The parameters non BCCHlayer exit threshold (LER), non BCCH layer exit thresholdpx (LEP), and non BCCH layer exit threshold nx (LEN) are usedto decide whether the MS's downlink signal level is good enough on theweaker frequency band.

Power Control (POC) radio network object parameters


Common BCCH Control

When radio frequency power control (POC) is created, the BSC selects theALPHA and GAMMA default values according to the BCCH frequencyband of the segment. If there is no BCCH TRX in the segment, and there ismore than one frequency band in use in the segment when POC iscreated, then GSM 900 default values are used if there exists at least oneGSM 900 or GSM 800 BTS in the segment.

The different radio propagation properties of the different frequency bandsof a multiband segment result in different radio coverages of the twobands. The maximum transmission power for the different frequencybands of a multiband segment needs to be adjusted separately in order tobetter maintain connection to MSs in the segment. Matching the radiocoverage to the same size on both bands of a multiband segment is doneby adjusting the maximum transmission power for the bands separatelywith band specific power controlling parameters BS TX pwr max and BS TXpwr max1x00.

SEG-specific Base Transceiver Station (SEG-BTS) radio network objectparameters

. direct GPRS access BTS

. SEG identification

. SEG name

For more information on radio network parameters, see BSS RadioNetwork Parameter Dictionary under Reference/Parameters in the PDFview.

Alarms

The segment object is invisible to the BSC alarm system. The alarms arefocused on the same radio network objects regardless of whether thesegment architecture is used or not. All the cell and BTS-specific alarmsare given per BTS object also in the segment environment. With thealarms that focus on the cell object, the alarm is given via the BCCH BTSof a multi BTS segment. The BSC generates alarm 7767 BCCH MISSINGonly for the BTSs having a BCCH configured. The congestion supervisionfor alarm 7746 CH CONGESTION IN BTS ABOVE DEFINEDTHRESHOLD is made in the BCCH BTS concerning the whole segment.

The supervision for alarm 7746 CH CONGESTION IN BTS ABOVEDEFINED THRESHOLD is based on the relation between received andrejected resource requests in a cell. It is a general view of the cell'scapability to serve mobile subscribers in its coverage area. In themultiband segment environment the rejection of a service request does notnecessarily mean that all the segment's resources are occupied. Because

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of the different capabilities of terminals and the difference between thepropagation properties of frequency bands the resources that areapplicable to individual resource requests vary case by case. A rejection ina segment means that all the resources that could be applied for a requestat that moment are occupied. Depending on the case this can mean all theresources of a segment or only part of them. In any case the congestionsupervision gives a good idea how the supply meets the demand for radiochannel resources in a cell.

Measurements and counters

The introduction of Common BCCH Control has not affected the basicstructure of statistics. The measurements are still collected per BTS in thesegment environment. In addition, the network service and managementsystem Nokia NetAct offers the possibility to have frequency band-specificstatistics and segment-specific statistics based on the BTS-specificmeasurements.

The introduction of the segment concept and the possibility to haveseveral BTS objects in one cell causes changes in the data collection ofsome cell level activities and in the BTS-specific counter interpretation inthe segment environment.

Common BCCH Control introduces some counters for the supervision ofintra-segment TCH handover based on load, intra-segment handover fromnon-BCCH layer based on signal level, and inter-segment handovers thattake place between separate BTSs of a segment. These are implementedin Handover Measurement and BSC Level Clear Code (PM)Measurement.

The non-BCCH layer offset measurement collects data of the signal leveldifferences between the BTSs of the BCCH frequency band and the non-BCCH frequency band. Based on the collected information, you can verifythe accuracy and tune the values of the non BCCH layer offset (NBL)parameters of the non-BCCH layer BTSs.

Common BCCH Control traffic measurement

When a BTS-specific statistical counter is updated in a procedure wherean entire segment is the target, the respective attempt counter is updatedfor the BCCH BTS of the segment. In traffic measurement this means thatall incoming channel allocation attempts are included in the statistics of theBCCH BTS of the target segment.


Common BCCH Control

If an allocation attempt is not successful, the rejection of the resourcerequest is updated according to the capabilities of the MS requesting theresource. Whenever the MS could accept a channel from a non-BCCHfrequency band, the resource request rejection is updated for a non-BCCHfrequency band BTS of the target segment, if there is one. If the requestreject cannot be updated in a BTS of any other resource type, it will beupdated for the BCCH BTS of the cell.

In case of an unsuccessful channel allocation attempt for an internalintercell handover, the attempt and the resource request rejection areupdated in the first segment of the handover candidate list. When thechannel allocation succeeds, the procedure is updated in a counter of theBTS where the channel was allocated. In this case the attempt counter isupdated for the BCCH BTS of the selected segment.

Common BCCH Control handover measurement

In the handover measurement, as well as in all other measurementscollecting statistics on handovers, the counters that have been describingintra-cell handovers inside a BTS are in segment environment showing thehandovers inside a segment. These include both handovers between asegment's BTSs and handovers within single BTSs. On the other hand thecounters of inter-cell handovers that used to give information on allhandovers between BTSs of a BSC are in segment environment collectinginformation of handovers that take place between BTSs of differentsegments.

Handover measurement introduces Common BCCH Control specificcounters to separate the intra-cell handovers in which calls move from oneBTS to another from the ones in which calls only change channels within aBTS.

The following 4 Handover Measurement counters are related to CommonBCCH Control:

Table 4. Counters of Handover Measurement related to Common BCCHControl

Name Number

INTRA CELL SUCCESS SDCCH HO BETWEEN BTSS 004131

INTRA CELL SUCCESS TCH HO BETWEEN BTSS 004132

HO ATTEMPT INTER BAND SDCCH 004133

INTRA CELL SUCCESS SDCCH HO BETWEEN BANDS 004134

HO ATTEMPT INTER BAND TCH 004135

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Table 4. Counters of Handover Measurement related to Common BCCHControl (cont.)

Name Number

INTRA CELL SUCCESS TCH HO BETWEEN BANDS 004136

SUCCESSFUL HO INTER BAND TCH 004159

UNSUCCESSFUL HO INTER BAND TCH 004161

HO ATTEMPT INTER BAND DUE LEVEL 004163

UNSUCC HO INTER BAND DUE LEVEL 004164

SUCC HO INTER BAND DUE LEVEL 004165

INTER SEGMENT SUCCESS SDCCH HO BETWEEN BANDS 004166

INTER SEGMENT SUCCESS TCH HO BETWEEN BANDS 004168

For more information, see 4 Handover Measurement under Reference/Counters/Performance indicators/Call control measurements in the PDFview.

General counters

In an intra-cell handover between BTSs inside a segment, the handoverattempt counter is updated for the source BTS of the handover. Thismakes it possible to gather information on the origin of intra-cell handoverswith the counters that were defined before the segment concept wasintroduced. When the intra-cell handover fails, the failure of the handoveris also updated for the source BTS of the handover. In the successful casethe update of the success counter is made for the BTS from which thechannel is allocated.

On the target side of an inter-cell handover with only one candidate celland in external handovers between BSCs, the BSC updates theappropriate attempt counter for the BCCH BTS of the target segment. Ifthe BSC is unable to allocate a channel for the handover, it also updatesthe failure for the BCCH BTS of the target segment. In a successful casethe BSC updates the appropriate success counter for the BTS in which theallocation has been made. In addition, if the handover fails after thechannel has been allocated, the failure is updated for the selected targetBTS.


Common BCCH Control

In inter-cell handovers with several candidate cells, the object for thehandover counter update on the target side varies depending on thesuccess of channel allocation. If the BSC is able to allocate a channel forthe handover, the counter updates on the target side are made for the BTSfrom where the channel has been allocated. In an unsuccessful channelallocation case the counters are updated for the BCCH BTS of the firstSEG on the target cell list of the handover.

Common BCCH Control specific counters

The Common BCCH Control specific handover measurement countersinclude attempt counters that are updated for the source BTS of ahandover. Other special counters for segment environment mainly collectinformation on completed handovers of certain types and are updated atthe target BTS of the intra-segment handover.

Common BCCH Control and BSC Level Clear Code (PM) Measurement

Following the established practice with the handover attempt causes andthe related handover measurement counters there are the respectivesuccess counters in the BSC Level Clear Code (PM) Measurement. Thefollowing counters are related to the inter-band handover attempts that areindicated by the Handover measurement counters 004133, 004135, and004169.

The following 51 BSC Level Clear Code (PM) Measurement counters arerelated to Common BCCH Control:

Table 5. Counters of BSC Level Clear Code (PM) Measurement related toCommon BCCH Control

Name Number

INTRA INTER BAND TCH HANDOVER 051135

INTRA INTER BAND SDCCH HANDOVER 051136

INTRA INTER BAND DUE LEV 051153

For more information, see 51 BSC Level Clear Code (PM) Measurementunder Reference/Counters/Performance indicators/Call controlmeasurements in the PDF view.

Common BCCH Control and Non-BCCH Layer Offset measurement

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The non-BCCH layer offset measurement collects data on how muchweaker the signal level of a BTS on the non-BCCH layer is compared tothat of the BCCH BTS. The measurement includes counters for absolutedifference values from -40 to +40 dB in 1 dB steps. All the samples that arebelow -40 dB are collected into a separate counter. In addition, thesamples that indicate a difference greater than 40 dB are collected in acounter of their own. The negative values are for the cases where thesignal level of the non-BCCH layer is actually stronger than that of theBCCH BTS.

The measurement samples are collected at the SACCH signalling ratefrom each MS with an ongoing call in a non-BCCH frequency band BTS.When defining the signal level differences between the bands, the BSCtakes into account the used power levels in order to establish an accuratevalue of the difference between the two frequency bands.

The non-BCCH layer offset statistics are collected BTS-specifically inevery BTS that is on the non-BCCH frequency band of a segment usingCommon BCCH Control. The operator can use the results of themeasurement to verify the accuracy of the non BCCH layer offset (NBL)parameters of the non-BCCH layer BTSs.

The following 92 Non-BCCH Layer Offset Measurement counters arerelated to Common BCCH Control:

Table 6. Counters of Non-BCCH Layer Offset Measurement related toCommon BCCH Control

Name Number

OFFSET SAMPLE BELOW -40 092000

OFFSET SAMPLE OF ZERO 092001

OFFSET SAMPLE OF +1 092002

... ...

OFFSET SAMPLE OF +40 092041

OFFSET SAMPLE ABOVE +40 092042

OFFSET SAMPLE OF -40 092043

... ...

OFFSET SAMPLE OF -1 092082

For more information, see 92 Non-BCCH Layer Offset Measurement underReference/Counters/Performance indicators/Call control measurements inthe PDF view.


Common BCCH Control

3.6 Impact on Network Switching Subsystem (NSS)

No impact.

3.7 Impact on NetAct products

NetAct support for Common BCCH Control and Multi BCF Control isavailable from OSS3.1 ED1 onwards. If this release is not available, it isnot recommended to activate Common BCCH Control and Multi BCFControl in the network. Otherwise the whole management of radio networkin the sites where Common BCCH Control and Multi BCF Control areavailable will not work.

NetAct Administrator

NetAct Administrator offers full support for Common BCCH Control andMulti BCF Control administration tasks, for example:

. Fast download and activation of Common BCCH Control and MultiBCF Control software to BTSs via Nokia NetAct tools

. Expandable software archives

. Storages for multiple software configurations

NetAct Monitor

Standard Nokia NetAct monitoring applications are also used formonitoring Common BCCH Control and Multi BCF Control.

NetAct Optimizer

Optimizer supports BSS Common BCCH Control and Multi BCF Control.Internally Optimizer creates cell objects based on segment ID and MasterBTS flag information. In geographical map view Common BCCH Controland Multi BCF Control cells (segments) are visible entirely; non-segmentBTSs are available normally. Two views are available in Topology view:new cell (segment) view and old common object model view (BSC-BCF-BTS). Adjacency, Power Control, and Handover Control objects are linkedto Master BTS in cell (segment).

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NetAct Planner

Nokia NetAct Planner release 4.1 includes a set of radio network andplanning features for Common BCCH Control and Multi BCF Control. Thisallows visibility of Common BCCH Control and Multi BCF Control in radionetwork planning: creation of Multi BCF master BTSs and Common BCCHallocations. Plans can be completed with Radio Access Configurator.

NetAct Radio Access Configurator (RAC)

NetAct Radio Access Configurator (RAC) provides network wide accessand tools to configure Common BCCH Control and Multi BCF Control. Therelated BTS radio parameters can be managed from NetAct Radio AccessConfigurator. In BSC, Common BCCH Control and Multi BCF Controlmanagement is handled via segment. In Radio Access Configurator thesegment management is done using a master BTS definition. For moreinformation, see Maintaining Multi-BCF Sites in Nokia NetAct ProductDocumentation.

NetAct Reporter

Reporting for Common BCCH Control and Multi BCF Control is done bycommon Nokia NetAct reporting tools. NetAct Reporter can be used tocreate reports from measurements related to Common BCCH Control. Thesegment replaces in many cases BTSs in reporting:

. presenting raw counters or KPIs result in segment ID level instead ofBTS level with the current ReportBuilder

. defining the object (for example, segment ID, BTS, etc.) aggregationmethod on top of the time aggregation formula in the Formula wizardwith ReportBuilder

. selecting the segment ID as hierarchy and segment ID as summarylevel in the dimension selection for report properties

Note that the BTS level is still applicable in some cases, although it is inmany cases replaced by segment.

NetAct Tracing

No impact.

3.8 Impact on mobile terminals

Common BCCH Control requires a multiband capable terminal.


Common BCCH Control

3.9 Impact on interfaces

No impact.

3.10 Interworking with other features

PGSM 900 - EGSM 900 BTS

If you are using the GSM 900 frequency band, the PGSM 900 and EGSM900 resources do not necessarily have to be configured as separate BTSobjects. It is also possible to have both the PGSM 900 and EGSM 900TRXs in a single BTS object, which enables BCCH recovery between theTRXs.

There are restrictions when the BCCH is on PGSM 900 frequency in aPGSM 900 - EGSM 900 BTS. For more information, see PGSM 900 -EGSM 900 BTS in BSC under Feature descriptions/Radio networkperformance in the PDF view.

BCCH allocation

In Common BCCH, the BCCH frequency of the segment is added amongthe BCCH frequencies that the MS should measure when the MS is activeon the non-BCCH band of the segment. This leads to the followingrestrictions:

. There can be only 31 frequencies on adjacent cell frequency list andBCCH Allocation frequency list.

. Only 5 of the strongest neighbours are included in the adjacent cellmeasurements.

SDCCH allocation

In a multiband Common BCCH segment, the Initial SDCCH channel for acall set-up is always allocated in the frequency band where also thesegment's BCCH is located. An exception to this rule is when thesegment's BCCH carrier is on EGSM 900 band. When the BCCH carrier ison EGSM 900 band, the possible PGSM 900 resources of the segment arealso available for the initial SDCCH allocation of a call.

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When an SDCCH is allocated for an external handover in a multibandCommon BCCH segment, the search may be restricted among the BCCHfrequency band resources of the segment. This depends on the frequencyband the BCCH is using. If the non-BCCH layer is regarded as a layer withless coverage (as indicated by the positive value of the non BCCH layeroffset parameter), only BCCH frequency band resources are used inSDCCH allocation for external handovers.

Dynamic SDCCH allocation

The dynamic SDCCH RTSLs can be utilised only in the BCCH frequencyband in a Common BCCH cell. This is due to the fact that the multibandcapabilities of an accessing MS are not known at the time of the initialSDCCH allocation.

When the segment's BCCH carrier is on EGSM 900 band, the possiblePGSM 900 resources of the segment are also available for the dynamicSDCCH allocation.

Queuing

Queuing is applied at the segment level. There is no priority betweendifferent mobile types; therefore the mobiles supporting all frequencybands are more likely to be allocated a channel.

There is no specific reason to vary the values of the parameters timelimit call and time limit handover with respect to the one-layernetwork setting.

The value of the parameter max queue length has to be reset, consideringthat the percentage is evaluated on the total number of TRXs (including allBTSs of the segment) and the resulting number should be lower than thenumber of available SDCCH channels on the BCCH serving layer band.This is because some capacity must be left to services that run on SDCCHonly (for example, SMS).

Some mobiles may be put into a queue even though all the TCH resourcesof the segment are not fully utilised (this is the case when the mobile in thequeue does not support the available capacity). In this case it is veryimportant to make sure that SDCCH capacity is still available for furtherrequests from mobiles supporting the available TCH capacity. For thisreason the margin between max queue length and the number of SDCCHchannels on the BCCH serving layer band should be greater than before.


Common BCCH Control

GPRS/EDGE

Each BTS object in a segment has its own GPRS terrritory. Theparameters that are used to define the size of GPRS territory are adjustedin each BTS.

When comparing the TCH load of a segment's BTS with the parameterBTS load in SEG, the BSC interprets RTSLs in GPRS territory as busychannels (excluding dedicated GPRS resources). This interpretationprevents the GPRS territory of a single BTS from shrinking unnecessarily,if there are other BTSs in the segment to which CS calls could betransferred from the BTS in question.

Note that you must define GPRS territory to the BCCH frequency band in acommon BCCH cell in which more than one frequency band is in use.Otherwise GPRS does not work properly in the cell. The reason for thisrequirement is that in cases when the MS RAC of the GPRS mobile is notknown by the BSC the TBF must be allocated on the BCCH frequencyband first. During the first TBF allocation the GPRS mobile indicates itsfrequency capability to BSC. After that other frequency bands of the cellcan be used for the GPRS mobile accordingly.

The interactions between the circuit switched radio resource managementof a segment and GPRS are explained in detail in TCH allocation inCommon BCCH segment environment. For the effects of the segmentconcept on the radio resource management of the packet switchedservices in the PCU, see GPRS in BSC under Feature descriptions/Data inthe PDF view.

Every GPRS BTS in a segment has to be connected to the same PCU.

For more information about GPRS territories, see GPRS/EDGE in BSCunder Feature descriptions/Data in the PDF view.

Pre-emption

When the segment architecture is used, Pre-emption is a segment levelfunction.

In a segment with several BTSs of different properties it is possible that aTCH request cannot be served even though all the TCH resources in asegment are not fully utilised. However, pre-emption is possible ifpermitted by the related parameters.

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The candidate for the forced actions is selected among the resource typesthat are indicated as reasonable in the resource request that initiates theseactions. In the candidate selection the criterion of the lowest possiblepriority is the most important one. When searching for the lowest prioritycall the different resource types are preferred so that the BTSs that usesame frequency band as BCCH BTS are the most preferred ones.

Intelligent Underlay-Overlay

In the segment environment, the use of Intelligent Underlay-Overlay is aBTS-specific functionality. Each BTS in a segment can have its ownregular and super-reuse layers. The super-reuse layer of a BTS can beaccessed only via the regular layer of the BTS.

Figure 5. IUO frequency groups in GSM 900 / GSM 1800 Common BCCHnetwork

Figure 6. IUO frequency groups in GSM 800 / GSM 1900 Common BCCHnetwork

The target for a super-reuse TCH request is always one BTS (a few TRXswithin the BTS) and not the whole segment as in resource requests ingeneral. The handover from regular resources to super-reuse resources ina BTS is the same regardless of whether segment architecture is used ornot.

P reg P super E reg E super D reg D super

P GSM 900 super E GSM 900 super GSM 1800 super

regular TRXs TRXs regular TRXs TRXs regular TRXs TRXs

GSM 800regular TRXs

GSM 800super TRXs

GSM 1900regular TRXs

GSM 1900super TRXs


Common BCCH Control

When an IUO handover from a super-reuse TRX to the regular resourcesof a BTS is performed, the information on the usability of different resourcetypes in the segment is decided based on the values of the parameter nonBCCH layer offset in the different BTSs of the segment. As a target, theBSC accepts the BTSs whose non BCCH layer offset value is less thanor equal to the value of the BTS where the handover was initiated. This isindicated in the figure Possible handover directions on a segment withdashed-line arrows going from the super-reuse layer of one BTS to theregular layer of another BTS in a segment.

The child cell concept is not supported in the BSC in which the segmentoption is enabled.

Direct Access to super-reuse layer is only supported inside the BTS objectwith the initial SDCCH, which must be in the BCCH band.

To get an accurate estimation of the C/I value of the Common BCCHsegment's non-BCCH frequency band layer, the estimation is based on themeasurement of the BCCH frequency in the segment. The C/I calculationis modified so that the segment's BCCH measurement result is usedinstead of the serving TCH measurement result.

Figure 7. Possible handover directions on a segment

For more information, see Intelligent Underlay-Overlay under Featuredescriptions/Radio network performance in the PDF view.

BTS1

Regular area

Super-reuse area

BTS2

Regular area

Super-reuse area

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Multi BCF Control

When Common BCCH Control is combined with Multi BCF Control, youare allowed to configure to one segment both BTSs of different frequencybands and BTSs of different base station types.

For more information, see Multi BCF Control under Feature Descriptions/Macrocellular in the PDF view.

Frequency Hopping

The multiband MS and the multiband network support Frequency Hoppingwithin each band of operation. Frequency Hopping between the bands ofoperation is not supported.

Frequency Hopping is managed by a BTS when the segment concept is inuse. In a PGSM 900 - EGSM 900 BTS, Frequency Hopping is possible ononly one of the two bands. In the segment architecture the resources ofdifferent types are grouped as separate BTSs. All the resource types havethe hopping parameters and the hopping groups of their own.

Figure 8. Hopping groups in a segment with GSM 900 and GSM 1800resources (BCCH on PGSM 900)

BB hoppingPGSM 900 BTS, EGSM 900 BTS, GSM 1800 BTS,

two hopping groups two hopping groups two hopping groups

RF hoppingPGSM 900 BTS, EGSM 900 BTS, GSM 1800 BTS,

one hopping group one hopping group one hopping group

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7


Common BCCH Control

Figure 9. Hopping groups in a segment with GSM 800 and GSM 1900resources (BCCH on GSM 800)

The segment architecture enables having BTSs without a BCCH TRX.This reduces the amount of hopping groups in the regular area of a BTS,because there is no need for a separate group for the BCCH TRX in RFhopping. In baseband hopping there is also no need for separating TSL0from the other TSLs in BTSs that do not contain a BCCH TRX. However,the separation between TSL0 and other TSLs remain and these areregarded as two different hopping groups. The user gives one set ofparameters for the TSL0 group and another for the other TSLs. A similarset of parameters can be given for both.

The segment model offers the opportunity to have several hopping groupseven though there are only resources for one band in a segment. Theoperator can form hopping groups by gathering the needed TRXs into oneBTS and have several BTSs of the same band. Each BTS has hoppingparameters of its own.

For more information, see Frequency Hopping under Feature descriptions/Radio network performance in the PDF view.

BB Hopping

GSM 800 BTSTwo hopping groups

GSM 1900 BTSTwo hopping groups

GSM 1900 BTSOne hopping group

RF Hopping

GSM 800 BTSOne hopping group

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

0 1 2 3 4 5 6 7

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High Speed Circuit Switched Data (HSCSD)

From the point of HSCSDthe effects of the segment structure appearmainly when allocating TCHs for HSCSD requests. The basic principlesthat apply for the TCH allocation in general are also valid in HSCSD cases.This means that the HSCSD resource allocation is made according to thecapabilities of an MS considering the radio conditions and the loads ofdifferent resource types.

Among the resource types that the BSC defines as reasonable, the TCHsearch is performed in a way that an HSCSD channel configuration thatbest fulfills the request is selected. Within a segment the HSCSDallocation is made in a BTS that has no restrictions based on the HSCSDload parameters rather than in a BTS where the allocation is restricted toinclude only one TCH.

The user can control the HSCSD traffic load between BTSs of a segmentby using BTS specific HSCSD load parameters HSCSD TCH capacityminimum,HSCSD cell load upper limit, HSCSD cell load lowerlimit and HSCSD regular cell load upper limit.

If necessary, in the segment environment one HSCSD downgrade persegment per received request is made. When the received request leadsto TCH allocation, the need for an HSCSD downgrade is examined in theBTS of the allocation. In case a free TCH cannot be found, the candidatefor the HSCSD downgrade is selected among the segment's BTSs that aredefined as appropriate targets for the request. A round robin method isused to direct separate downgrade attempts to different BTSs in thesegment. In each BTS the downgrade decision is based on the HSCSDparameters of the particular BTS.

For more information, see HSCSD and 14.4 kbit/s Data Services in BSCunder Feature descriptions/Data in the PDF view.

Enhanced Coverage by Frequency Hopping and Handover Supportfor Coverage Enhancements

Enhanced Coverage by Frequency Hopping and Handover Support forCoverage Enhancements can be used in the BCCH BTS of commonBCCH controlled cells.

For more information, see Handover Support for Coverage Enhancementunder Feature descriptions/Macrocellular in the PDF view and EnhancedCoverage by Frequency Hopping under Feature descriptions/Radionetwork performance in the PDF view.


Common BCCH Control

Extended Cell, Extended Cell Range

In a segment environment, only BCCH BTSs can have extended areaTRXs.

For more information, see Extended Cell under Feature descriptions/Macrocellular in the PDF view.

Directed Retry

Directed Retry or Intelligent Directed Retry can be triggered even if allresources of a segment are not completely in use. It requires that all theresources that an accessing MS could utilise under the current conditionsare unavailable.

Since the Directed Retry procedure reduces SDCCH capacity, theDirected Retry timers should not be set too high and SDCCH capacityshould be dimensioned with the proper margin, to avoid SDCCH blocking(due to the DR procedure) for any mobile supporting the available TCHcapacity.

For more information, see Directed Retry in BSC under Featuredescriptions/Radio network performance in the PDF view.

Direct Access to Desired Layer/Band

The purpose of Direct Access to Desired Layer/Band is to direct traffic inthe call setup phase from the SDCCH of a macrocell/GSM 900/800 cell toa TCH of a micro cell/GSM 1800/1900 cell whenever possible.

In the segment environment, DADL/B can be used to direct traffic betweensegments. The loads are evaluated per segment, adjacency definitions arebetween segments, and DADL/B handovers are made between segments.

For more information, see Direct Access to Desired Layer/Band (DADL/B)under Feature descriptions/Radio network performance in the PDF view.

Trunk Reservation and Common BCCH Control

The control of Trunk Reservation is removed from the BTS level to thesegment level. The defining of the number of the available TCHs in asegment is made according to the capabilities of the accessing MS. Incase of PGSM 900 MS only the respective resources are examined. Incase of a multi band terminal both BCCH frequency band and non-BCCHfrequency band resources are included in calculations. Non-BCCH

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frequency band resources are included even though the MS cannot utilisethem immediately because of bad radio conditions. However, the MS canbe handed over to the non-BCCH frequency band as the conditionsimprove.

For more information, see Trunk Reservation under Feature descriptions/Value added services in the PDF view.

Advanced Multilayer Handling

The BSC-controlled traffic-reason handover is a segment level procedure,including the related parameters. The loads are evaluated per segment,and the idea is that the power budget margin is dynamically changed todirect the MSs at the segment border to less loaded adjacent segments.

Nevertheless, if each segment is dimensioned to handle the neededcapacity (as it should be with Common BCCH Control, considering thatthree different bands can be used and up to 36 TRX objects are allowed ina segment), the traffic should be smoothed out among the BTSs within asegment, rather than directed to adjacent segments. Therefore, whenCommon BCCH Control is active and the segments are multiband, theAdvanced Multilayer Handling is less beneficial.

For more information, see Advanced Multilayer Handling, IntelligentUnderlay-Overlay and Dual Band Network Operation under Featuredescriptions/Radio network performance in the PDF view, and RF PowerControl and Handover Algorithm under Functional descriptions//Radionetwork performance in the PDF view.

Minimum acceptable C/N ratio in channel allocation

If the value of the parameter CN threshold varies between the BTSs ofthe same resource type, the BSC selects the highest value for calculation.The recommendation for a certain resource type in the segment isdisabled when the value is not used even in one of the BTSs of the sameresource type.

MS power level optimisation in handover and call setup

If the value of the parameter optimum Rx lev UL varies between the TRXsof the BTSs of the same resource type, the BSC selects the highest valuefor calculation. The optimum uplink RF signal level for a certain resourcetype in the segment is disabled when the value is not used even in one ofthe TRXs of the BTSs of the same resource type.


Common BCCH Control

MSC controlled TRHO & resource indications with Common BCCHControl

The MSC controlled traffic reason handover and the related resourceindications are segment level procedures.

In the spontaneous resource indication method the segment levelparameter BTS load threshold is used when defining the need to sendthe resource indication.

In selecting the candidate call for the traffic reason handover the BCCHBTS is preferred. If there are not enough of suitable candidates in theBCCH BTS, the candidates are selected from other BTSs of the segment.The other BTSs of the segment are preferred according to their frequencyband in the following way:

. BTSs using BCCH frequency band are preferred to BTSs usingother than BCCH frequency band.

Note that when the BCCH is on the EGSM 900 band then also the PGSM900 resources of the segment can be regarded as belonging to the EGSM900 frequency band.

When there are three frequency bands (PGSM 900, EGSM 900 and GSM1800) in use in Common BCCH segment the preference between the twonon-BCCH frequency bands is made in the following way:

. If BCCH is on PGSM 900 frequency band EGSM 900 is preferred toGSM 1800.

. If BCCH is on GSM 1800 frequency band PGSM 900 is preferred toEGSM 900.

For more information, see Traffic Reason Handover in BSC underFunctional descriptions//Radio network performance in the PDF view.

Radio network supervision

The congestion supervision for alarm 7746 CH CONGESTION IN CELLABOVE DEFINED THRESHOLD is monitored on the segment level sincethe target for a channel request is a segment. In a segment with severalBTSs, the channel congestion supervision is made in the BCCH BTS forthe whole segment. And a possible alarm on congestion, even if it isidentified with the BCCH BTS, describes the congestion level of the wholesegment.

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For more information, see Radio Network Supervision in BSC underFunctional descriptions/Operability in the PDF view.

FACCH Call Setup

FACCH Call Setup means allocating a TCH for the signalling phase of acall in a SDCCH congestion. Thus, the same restrictions apply for FACCHCall Setup as for SDCCH allocation: it is limited in the BCCH frequencyband. As an exception to the rule, when the segment's BCCH carrier is onEGSM 900 band, the possible PGSM 900 resources of the segment arealso available for the FACCH Call Setup.

In the FACCH call setup the SDCCH phase during which the capabilityinformation of an accessing terminal are received is totally skipped and thecall is put directly to a TCH channel, so there is no information on theusability of the possible other resource types than that of the segment'sBCCH TRX at the time the TCH is allocated. Because of this a TCH for anFACCH setup is allocated within the resource type that the BCCH TRX ofthe segment represents.

Adaptive Multi-rate speech codec (AMR) and Common BCCH Control

Decisions on the need for packing AMR full rate (FR) calls to half rate (HR)AMR calls is based on the load situation of each individual BTS also in thesegment environment. If FR AMR calls in a certain BTS should be packedis decided based on the load of that BTS only. Furthermore, the intra-cellhandovers that perform the actual packing of calls are implemented asBTS internal events.

For more information, see Enhanced Speech Codecs: AMR and EFRunder Feature descriptions/Radio network performance in the PDF view.

External handover

When a TCH is allocated for an external handover in a multiband CommonBCCH segment, the search may be restricted among the BCCH frequencyband resources of the segment. This depends on the frequency bandBCCH is using. If the non-BCCH layer is regarded as a layer with lesscoverage (as indicated by the positive value of the non BCCH layer offsetparameter), only BCCH frequency band resources are used in TCHallocation for external handovers.


Common BCCH Control

TRX prioritisation in TCH allocation

The possibility to favour or avoid the BCCH TRX in call assigning has beenmaintained to some extent in the segment environment. This is examinedafter the BTSs of a segment have been compared on the basis of theirloads and their respective load parameters.

Shutdown with forced handover

When locking a single BTS of a segment, an intra-cell handover ispossible. If a BCCH BTS of the segment is in the state locked whenanother BTS in the SEG is shut down, only an inter-cell handover ispossible. The same applies when the BCCH BTS itself is shutting down.

Dual Band

Common BCCH Control replaces Dual Band. However, Dual Band isavailable for cases where BTS site and cell definitions still use separateBCCHs for each of the bands. Use Common BCCH if possible.

GSM-WCDMA Inter-System Handover and GSM - TD-SCDMAInterworking

If GSM-WCDMA Inter-System Handover and GSM - TD-SCDMAInterworking are used together with Common BCCH Control the maximumnumber of adjacent cells and frequencies in a BA list is 30.Dual Transfer Mode

The BSC decides the usability of a segments BTSs for a Dual TransferMode (DTM) call by using the RX-level based traffic channel (TCH) accesscontrol. For more information on DTM, see Dual Transfer Mode underFeature descriptions/Data in the PDF view.

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Common BCCH Control

4 Common BCCH Control systeminformation messages

4.1 Common BCCH Control Cell Allocation

Cell Allocation (CA) is a subset of radio frequency channels that isallocated to each common BCCH segment. One of Cell Allocation's radiofrequency channels is used to carry synchronisation information and theBCCH. This is known as the BCCH carrier. The subset of the CellAllocation frequencies that is allocated to a particular MS is known as theMobile Allocation.

The MS uses the CA list to decode Mobile Allocation when frequencyhopping is applied. The multi-band MS and multi-band network supportfrequency hopping within each band of operation. Frequency hoppingbetween the bands of operation is not supported.

Although frequencies of several bands can be in use in a segment, theyare kept apart by having separate Cell Allocation and Mobile Allocationlists for each frequency band of the segment. It is not certain whether allmobile stations can cope with CA lists including frequencies that the MSitself does not support in a common BCCH environment. In addition,combining the frequencies of different bands in one frequency list restrictsthe number of frequencies that can be included in frequency hopping. Thisis because of the limitations of the absolute radio frequency number(ARFCN) encoding in the system information messages.

An exception to the above-mentioned rule is when the BCCH of a segmentis on the EGSM 900 frequency band and there are also PGSM 900resources in the segment. In this case, a common CA list for all the GSM900 frequencies in the segment is used. From the point of view of the MS'scapabilities, it is safe to have a common CA list because all the accessing

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Common BCCH Control system information messages

GSM 900 mobile stations in the segment support both of the GSM 900frequency bands. However, the number of frequencies on such a commonCA list is limited to 16 (17, if ARFCN 0 is included) because of the neededARFCN number encoding method used in this case.

The broadcast of the CA list to the MSs in the System Information 1message includes only the segment's frequencies of the band on whichthe BCCH carrier is.If the BCCH carrier of a segment is on PGSM 900,then PGSM 900 and EGSM 900 are regarded as separate frequencybands. If the BCCH carrier of a segment is on EGSM 900, all the GSM 900resources of the segment can be regarded as belonging to the BCCHfrequency band, that is, the EGSM 900 frequency band.

During the call set-up and handover procedures each MS is informed onthe frequencies of the band the MS is going to use next with eitherAssignment Command or Handover Command.

4.2 Common BCCH Control Mobile Allocation

Mobile Allocation is the subset of the Cell Allocation allocated to aparticular MS. The purpose of the Mobile Allocation information is toprovide the MS with the Cell Allocation RF channels, which are used in themobile hopping sequence.

The MA list indicated to the MS in the Assignment Command and theHandover Command is a band-specific list formed according to thefrequency band the MS is directed to. In the Immediate AssignmentCommand, the MA list of the band containing the segment's BCCH isalways included.

When a segment's BCCH carrier uses an EGSM 900 frequency, the CA listin the System Information 1 message also includes the possible PGSM900 frequencies of the segment. This enables the use of both PGSM 900and EGSM 900 frequencies in the MA frequency list already in theImmediate Assignment procedure. When the segment's BCCH carrieruses a PGSM 900 frequency, the CA list in the System Information 1message includes only PGSM 900 frequencies, which prevents the use ofthe possible EGSM 900 frequencies of the segment in the MA list at theImmediate Assignment phase.


Common BCCH Control

4.3 Common BCCH Control BCCH allocation

The sending of BCCH Allocation and system information in the commonBCCH networks is mainly similar to those used in the traditional networksof single BTS cells. The adjacency information sent to the MS is based onthe BCCH frequency of a common BCCH segment. Other frequencylayers in the segment are invisible to the MSs.

However, in order for the BSC to be able to make reasonable decisions oncertain handovers for an MS on the non-BCCH frequency layer of asegment, the BCCH frequency of the segment itself is added among theBCCH frequencies the MS should measure when on the non-BCCHfrequency band. A modified BA list is sent to an MS on the non-BCCHfrequency layer in System Information type 5 message on the SACCH.

When the MS is on a segment's non-BCCH frequency layer, there can onlybe 31 frequencies in the adjacent cell and BA lists. Only five of thestrongest neighbours are included in the adjacent cell measurements asthe BCCH of the serving segment itself is added among the frequencies tobe measured.

For an overview, see Overview of Common BCCH Control in BSC.

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Common BCCH Control system information messages


Common BCCH Control

5 Radio resource management andCommon BCCH Control

5.1 SDCCH allocation in Common BCCH segment

Stand-alone dedicated control channels (SDCCHs) are allocated forsignalling purposes, immediate assignments, intra-BSC handovers, andinter-BSC handovers. The channel allocation algorithm in the BSC selectsthe SDCCH in all these situations.

SDCCH allocation from a segment with BTSs from different frequencybands is based on the frequency capability information of the accessingMS and the usability of the radio resources. The accessing MS sendsfrequency capability information to the BSC in the Classmark informationmessage. The usability of the radio resources in different frequency bandsfor the accessing MS is defined by the power control and handoveralgorithm in the BSC.

Selection of BTSs in Common BCCH segment

Immediate assignment

Even though there are resources of several frequency bands in a commonBCCH segment, the initial SDCCH must always be allocated from theBCCH frequency band. This is because the multiband capabilities of anaccessing mobile station are not known at the time of the initial SDCCHallocation.

Even if the capabilities of an accessing MS were known already in thebeginning, it would not be possible to define the usability of the non-BCCHfrequencies of the segment. This is because the MS starts sendingmeasurement reports only after it has been moved to a dedicated channel.

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Radio resource management and Common BCCH Control

Because of these restrictions the SDCCH for immediate assignment mustbe selected among the BTSs using the BCCH frequency band of thesegment. BTSs using other frequencies are not allowed to be used. Thechannel allocation algorithm selects the BTSs using the BCCH frequencyband as targets for an SDCCH selection.

An exception to the above-mentioned rules is when the segment's BCCHcarrier is on EGSM 900 band. In that case the segment's possible PGSM900 resources are also available for the initial SDCCH allocation becausean MS supporting the EGSM 900 band is always capable of supporting thePGSM 900 frequency band and because these two bands are regarded asequal from the radio properties' point of view.

Intra-BSC handover

In intra-BSC handover the channel allocation algorithm receives theinformation about the frequency capability of the accessing MS and theusability of radio resources in different frequency bands. The usability ofradio resources in different frequency bands is calculated by the powercontrol and handover algorithm. Based on this information the channelallocation algorithm selects certain BTSs of the segment as targets ofSDCCH selection.

Inter-BSC handover

In inter-BSC handover the channel allocation algorithm in the target BSCreceives the information about the accessing MS's frequency bandcapability. The usability of radio resources in different frequency bands isdefined based on the value of the parameter non BCCH layer offset(NBL). If the MS is capable of using the BTS's frequency band and theparameter non BCCH layer offset (NBL) of the BTS is less than orequal to zero, the BTS is selected as the target for SDCCH allocation.

Selection of TRX, RTSL and channel in Common BCCH Control

Having selected the BTSs from which the SDCCH can be allocated, thechannel allocation algorithm selects TRX, RTSL, and the channel to beused. The principles of selecting the TRX, RTSL, and the channel aredescribed below.

The channel allocation algorithm divides the BTSs into groups accordingto their frequencies:


Common BCCH Control

. BTSs using the BCCH frequency band form one group.

. BTSs using other frequency band than BCCH form one group.

. If the BCCH is on EGSM 900 band, the BTSs using PGSM 900belong to the group of BCCH frequency band.

The channel allocation algorithm calculates the SDCCH load of each BTSgroup. In SDCCH load calculation only the static SDCCH resources aretaken into account.

If there are idle static SDCCH resources in some group, the load of thegroup is the most decisive factor in TRX/RTSL/channel selection. Thechannel is allocated from the BTS group which has the lowest load. TheTRX/RTSL/channel selection from the TRXs of the selected BTS group ismade according to the following principles:

The channel allocation algorithm selects a suitable (TRX, RTSL) pair byusing the TRX-specific resource information. If possible, the pair to beselected is not the last seized pair.

There are two methods for selecting (TRX, RTSL) pairs among staticSDCCH resources depending on the hopping method and TRXprioritisation in the cell.

The method used in radio frequency (RF) hopping BTSs with RF hoppingTRX prioritisation:

. In the first phase all SDCCH TRXs, except BCCH TRX, areexamined up to the start

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Common BCCH

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