Common BCCH System Feature

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Common BCCH System Feature

Description

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2002546

Nokia GSM/EDGE BSS11 SystemDocumentation Set



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Common BCCH System Feature Description



Contents

Contents 3

1 Overview of GSM/EDGE Common BCCH 5

2 System impact of Common BCCH 132.1 Requirements 132.1.1 Hardware Requirements 132.1.2 Software Requirements 142.1.3 Frequency band support for Common BCCH 142.2 Impact on transmission 152.3 Impact on BSS Performance 152.3.1 Common BCCH impact on OMU signalling 152.3.2 Common BCCH impact on TRX signalling 16

2.3.3 Impact on BSC 162.4 User Interface 162.4.1 MMI 162.4.2 BTS parameters 172.4.3 BSC parameters 172.4.4 BSS Parameters 182.5 Impact on NSS 212.6 Impact on OSS 222.7 Impact on Interfaces 242.7.1 Impact on A Interface 242.7.2 Impact on Abis Interface 242.7.3 Impact on Gb Interface 242.8 Feature Interoperability 252.9 Impact on mobile terminals 33

3 Planning Common BCCH 353.1 Common BCCH and handover 353.2 Common BCCH and channel allocation 373.3 SDCCH dimensioning with Common BCCH 39

4 Implementing Common BCCH 414.1 Overview of implementing Common BCCH 414.2 Creating a multiband cell (segment) 424.3 Cancelling the expand of the segment 524.4 Moving a BTS from one segment to another existing segment 56



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Contents








1 Overview of GSM/EDGE Common BCCH

The Common BCCH feature allows the integration of resources from different

frequency bands into one cell. A common BCCH of a cell is configured in only

one of the bands of operation when resources across all bands are co-located and

synchronized.



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Overview of GSM/EDGE Common BCCH



Figure 1. GSM900/GSM1800 Common BCCH configuration

The following frequency band combinations are supported:

. PGSM 900 / EGSM 900

. PGSM 900 / GSM 1800

. PGSM 900 / EGSM 900 / GSM 1800

/ / /

O&M

O&M

Cell 1

GSM900 (BCCH) /GSM1800

Cell 3

GSM900 (BCCH) /GSM1800

Cell 2GSM900 (BCCH) /

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






. EGSM 900 / GSM 1800

. GSM 800 / GSM 1900.

The BCCH carrier is allowed in any of the supported frequency bands, except that the common BCCH is allowed in the EGSM900 frequency band only if there

is no PGSM900 in use in the network.

Benefits

The following are the benefits of using common BCCH control:

. Improved trunking gain

. Use of signalling channels is optimised by sharing them between bands.

.

The absence of a BCCH channel (in non-BCCH frequency band) leads to areduction of the overall interference and allows more freedom in frequency

allocation with improved quality.

. Reduced number of cells in the network

. Reduced number of Location Area Codes

. Reduced number of neighbouring cells

. Multi-layer network simplified into one-layer network

. Quality improvement due to decreased number of handovers between

frequency layers; calls directed to an appropriate layer in call set-up.

Segment and BTS object

Segment is a new Radio Network Object introduced to support Common BCCH,

Multi-BCF, and EDGE. The properties of a segment are the following:

. A segment equals a telecom cell. Whenever segment is mentioned, it is a

cell as we normally use.

. 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 properties of BTS Object are:



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. A BTS in a segment must consist of TRXs of the same frequency band

(PGSM 900, EGSM 900, GSM 1800, GSM 800, GSM 1900 separated).

. A BTS in a segment must consist of TRXs of the same base station site

type (Talk-family and UltraSite separated).

. A BTS in a segment must consist of TRXs of the same radio technology

(GSM and GSM/EDGE separated).

. The maximum number of TRXs in segment is 36.

Figure 2. Segment and BTS Object in Common BCCH

A typical Common BCCHs BTS configuration is shown in the figure. When

considering Common BCCH, segment-specific parameters and BTS specific

parameters should be taken into account. In many cases, BTS and frequency band

are the same but in some case 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 parameters need to be

considered in this case.

The allocation of a dedicated channel (SDCCH or TCH) inside a multiband

segment (that is, with BTSs from different frequency bands) is based on:

BCF BCF BCF

BTS BTS BTS

PGSM 900

PGSM 900

BCCH

EGSM900

GSM 1800

SEGMENT

Segment specificparameters

BTS specific parameters






. 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 using a new

BTS parameter, nonBCCHLayerOffset.

Mobile frequency capability

Different classes of mobiles can be defined according to their frequency

capabilities.

The information of the frequency capabilities of the mobile station is included in

the Mobile Station Classmark 2 and Mobile Station Classmark 3 Information

Elements.

The Mobile Station Classmark 2 Information includes information on the possible

EGSM 900 capability of the MS. The Mobile Station Classmark 3 Information

Element defines all the frequency bands supported by the MS and the MS power

capabilities in each supported frequency band.

The network receives the Mobile Station Classmark 2 IE in the Establish

Indication message. The Mobile Station Classmark 3 IE is received in the

Classmark Change message. The BSC receives both of these messages while the

related mobile station is on a dedicated signalling channel (SDCCH).

Intra-segment resource usability estimation

When the BSC has received both information about the MS frequency band

capability and about the downlink received BCCH signal level (measurement

report), it defines the usability of different resource types of the segment.

The following formula is used for resource usability estimation whenever a

channel inside the segment has to be assigned (in intra-segment SDCCH-SDCCH

handovers, TCH allocations, or intra-segment TCH-TCH handovers).

RXLEV_DL -nonBCCHLayerOffset>=nonBCCHLayerAccessThreshold

If the MS is on a BCCH layer channel, the RXLEV_DL is the terminal received

signal level on the channel. If the MS is using a non-BCCH layer channel, the

RXLEV_DL is the downlink signal level of the BCCH carrier of the segment.



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Inter-segment resource usability estimation

When the BSC has defined a need for an inter-segment (SDCCH-SDCCH or

TCH-TCH) handover based on the measurements of the serving channel, the

usability of the different resource types of each candidate segment is decided

using the BCCH measurement results for the segment and the values of parameter

nonBCCHLayerOffset for different resource types in the segment according

to the criterion:

AV_RXLEV_NCELL(n) nonBCCHLayerOffset>= RxLevMinCell(n)

where

RxLevMinCell(n) is the level which the signal level in the adjacent segment must

exceed in order for the handover to the adjacent segment to become possible.

In a handover between two BSCs, the radio link measurements related to the

target segment are available on the source side BSC only. It is therefore not

possible to use the radio link measurements to define the usability of the non-

BCCH layer resources on the target side. In this case the decisions are based on

the nonBCCHLayerOffset parameter. If the non-BCCH layer is regarded as a

layer with less coverage (as indicated by the positive value of the

nonBCCHLayerOffset parameter), only BCCH frequency band resources are

used in channel allocation for external handovers.

Restrictions

1. In the band where the BCCH carrier resides, the common BCCH

controlled segments must be the same throughout the whole network.

BCCH is allowed in the EGSM 900 frequency band only if there is no

PGSM 900 frequency band in use in the network.

2. In the Common BCCH feature the BCCH frequency of the segment is

added among the BCCH frequencies that the MS should measure when the

MS is active on the non-BCCH band of the segment. This leads to the

following restrictions:

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

.

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

3. In a multi-band Common BCCH, the Initial SDCCH channel for a call set-

up is always allocated in the frequency band where also the segment's

BCCH is located.






When an SDCCH is allocated for an external handover in a multi-band

Common BCCH segment, the search may be restricted among the BCCH

frequency band resources of the segment. This depends on the frequency

band the BCCH is using. If the non-BCCH layer is regarded as a layer with

less coverage (as indicated by the positive value of the

nonBCCHLayerOffset parameter), only BCCH frequency band

resources are used in SDCCH allocation for external handovers.

4. In a multiband Common BCCH segment, the TCH for a FACCH setup is

always allocated in the BCCH frequency band of the segment.

5. The dynamic SDCCH RTSLs can be utilised only in the BCCH frequency

band in a Common BCCH cell. This is due to the fact that the multi-band

capabilities of an accessing MS are not known at the time of the initial

SDCCH allocation.

6. The multi-band MS and the multi-band network support FrequencyHopping within each band of operation. Frequency Hopping between the

bands of operation is not supported.

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

TRXs.

8. When a TCH is allocated for an external handover in a multiband Common

BCCH segment, the search may be restricted among the BCCH frequency

band resources of the segment. This depends on the frequency band BCCH

is using. If the non-BCCH layer is regarded as a layer with less coverage

(as indicated by the positive value of the nonBCCHLayerOffset

parameter), only BCCH frequency band resources are used in TCHallocation for external handovers.

9. The super-reuse layer of a BTS in a segment with several BTSs can be

accessed only via the regular layer of the BTS.

Handover from super-reuse resources back to the regular layer is not

restricted totally inside the source BTS. But it is limited among the

segment's BTSs that can be regarded as stronger than or equal to the source

BTS (as indicated by the values of the respective

nonBCCHLayerOffset parameters).

Thechild cell concept is not supported in a BSC that has the segment

option enabled.

10. GSM-WCDMA Inter-System Handover and Common BCCH Control.

If the features GSM-WCDMA Inter-System Handover and Common

BCCH Control are used together the maximum amount of adjacent cells

and frequencies in a BA list is 30.



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Common BCCH parameters

See chapter BSS Parameters.

non-BCCHLayerOffset

See chapter BSS Parameters.

Note

Common BCCH is an optional BSS feature.

Common BCCH and handover

Common BCCH and channel allocation

SDCCH dimensioning with Common BCCH

Overview of implementing Common BCCH






2 System impact of Common BCCH

2.1 Requirements

2.1.1 Hardware Requirements

Table 1. This table indicates whether

the feature requires additional

or alternative hardware or

firmware.

Network

element

Hardware/

Firmware required

BSC No requirements

BTS Yes, RF units are

band specific, and

correct RF units are

needed for the

supported frequency

bands.

TC No requirements

SGSN No requirements

Common BCCH requires a multi band capable terminal.



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System impact of Common BCCH



2.1.2 Software Requirements

Table 2. Network elements requiredsoftware.

Network

element

Software release

required

MSC No requirements

Nokia NetAct OSS3.1 ED1

(Enhancement

Delivery)

BSC S11

SGSN No requirements

NetAct Planner 4.0

Nokia 2nd Gen. Does not support this

feature

Nokia Talk-family DF6.0

800/1900 Common

BCCH not supported.

Nokia PrimeSite Does not support thisfeature

Nokia MetroSite CXM4.0

Nokia InSite Not supported by

Common BCCH

Nokia UltraSite CX4.0

2.1.3 Frequency band support for Common BCCH

The following frequency bands support Common BCCH:

. GSM 800

. GSM 900

. GSM 1800

. GSM 1900






For more detailed information, see Overview of GSM/EDGE Common BCCH .

Band Specific Power Controlling Parameters for Common BCCH

The different radio propagation properties of the different frequency bands of a

multiband segment result in different radio coverages of the two bands. The

maximum transmission power for the different frequency bands of a multiband

segment needs to be adjusted separately in order to better maintain connection to

MSs in the segment. Matching the radio coverage to the same size on both bands

of a multiband segment is done by adjusting the maximum transmission power

for the bands separately with Band Specific Power Controlling Parameters.

See Power control parameter handling in BSC parameters.

2.2 Impact on transmission

No impact.

2.3 Impact on BSS Performance

2.3.1 Common BCCH impact on OMU signalling

Table 3. Common BCCH impact on OMU signalling

Network element Impact

BTS No impact

BSC No impact

OSS No impact



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2.3.2 Common BCCH impact on TRX signalling

Table 4. Common BCCH impact on TRX signalling


BTS No impact

BSC No impact

OSS No impact

2.3.3 Impact on BSC

Table 5. Impact on BSC units

BSC unit Impact

MCMU No impact

BCSU No impact

PCU No impact

2.4 User Interface

2.4.1 MMI

Table 6. MML


BSC This feature is managed with BSC MMI.

OSS Common BCCH feature has an impact on

OSS.

MSC No impact






2.4.2 BTS parameters

The feature cannot be managed with BTS MMI.

2.4.3 BSC parameters

Base station controller parameter handling in BSC

The new parameter IntraSegSdcchHoGuard (ISS) is added to BSC handling

MML.

Base transceiver station handling in BSC

New parameters are added to BTS-MML: BTSLoadInSEG (LSEG),

NonBcchLayerOffset (NBL), MsTxPwrMaxCCH1x00 (TXP2),GPRSMsTxPwrMaxCCH1x00 (GTXP2), GPRSNonBcchLayerRxlevUpper

(GPU), GPRSNonBcchLayerRxlevLower (GPL), DirectGPRSAccessThreshold

(DIRE), SegmentId (SEG), and SegmentName (SEGNAME). Parameters

MsTxpwrMaxCCH (TXP1) and GPRSMsTxPwrMaxCCH (GTXP1) are used

only when the BCCH of the segment is either on the GSM800 or GSM900

frequency band.

Handover control parameter handling

New parameters are added to HOC-MML: NonBcchLayerAccessThreshold

(LAR), NonBcchLayerExitThreshold (LER), NonBcchLayerExitThresholdPx

(LEP), NonBcchLayerExitThresholdNx (LEN).

Power control parameter handling

When POC is created, PORTER selects the ALPHA and GAMMA default values

according to the BCCH frequency band of the segment. If there is no BCCH TRX

in the segment, and there are more than one frequency bands in use in the

segment when POC is created, then GSM900 default values are used if there

exists at least one GSM900 or GSM800 BTS in the segment.

See also parameters bsTxPwrMax and bsTxPwrMax1x00 in the table

Common BCCH parameters.

Adjacent cell handling

One new parameter GPRSMsTxPwrMaxCCH1x00 (GTXP2) is added to adjacent

cell handling MML.



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2.4.4 BSS Parameters

Common BCCH parameters

Q3 BSC MML Object Range Default

value

Description

intraSeg

SDCCHGuard

BSC 0 - 255 (s) 255 With this parameter you define the

guard time for attempting an SDCCH

handover from the BCCH BTS

resource layer to another resource

layer in a segment.

btsLoadInSeg BTS 0 - 100(%) 70 With this parameter you determine

the load limit for a BTS. It is used in

controlling the load distribution

between BTSs in a segment.

SegmentId BTS - Same value

as bts_id

The value range depends on the BSC

hardware configuration and the

corresponding options.

segmentName BTS 1 - 15

characters

Same name

as BTS's

name

With this parameter you identify the

segment by its name.

nonBCCH

LayerOffset

BTS -40 - +40

dBm

0 dBm With this parameter you define

whether the predefined offset margin

is used when evaluating the signal

level of the non-BCCH layer.

nonBCCH

LayerAccessThr

Segment -110 - -47

dBm

-90 With this parameter you define a

threshold value for the estimated

downlink signal level on non-BCCH

layer for a moving MS from BCCH

layer to non-BCCH layer.

nonBCCH

LayerExitThr

Segment -110 - -47

dBm

-95 With this parameter you define a

threshold value for the measured

downlink signal level on non-BCCH

layer for a moving MS from non-

BCCH layer to BCCH layer.

nonBCCH

LayerExitThr: px

Segment 1 - 32 1 With this parameter you define the

total number of the averaged values

of the signal strength downlink

measurements for triggering the

handover.

nonBCCH

LayerExitThr:nx

Segment 1 - 32 1 With this parameter you define the

number of averaged signal strength

downlink measurements for triggering

the handover.







value

Description

msTxPwrMaxCCH Segment 5..43 dBm

with 2 dBm

step

33 dBm With this parameter you define the

maximum transmission power an MS

may use when accessing a CCH in

the cell for GSM 900/800 bands.

gprsMsTxpwrMaxC-

CH

Segment 5..43 dBm

with 2 dBm

step


maximum transmission power level a

mobile station can use when

accessing a packet control channel in

the cell for GSM 900/800 bands.

msTxPwrMaxCCH1-

x00

Segment For GSM

1800

0...30dBm

with 2 dBmstep

For GSM

1900 0...32

dBm

with 2 dBm

step and 33

dBm


maximum transmission power an

MS may use when accessing a CCH

in the cell for GSM 1800/1900 bands.



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value

Description

gprsMsTxPwrMaxC-

CH1x00

Segment For GSM

1800

0...36dBm

with 2 dBm

step

For GSM

1900 0...32

dBm

with 2 dBm

step and 33

dBm

30 dBm

GPRSNonBCCHRx-

levLower

BTS -110...-47

dBm

-100 dBm With this parameter you define the

threshold when a reallocation to a

better BTS must be made. BTS with

the direct GPRS access BTS option

on is selected. If there are no BTSs

with direct GPRS access BTS set to

on, the BTS with the lowest non

BCCH layer offset is selected.

GPRSNonBCCHRxle-

vUpper

BTS -110...-47

dBm

-95dBm With this parameter you define the

minimum power level the MS has to

receive to allocate resources from the

BTS.

directGPRSac-

cessBts

BTS -40...40 dBm 0 dBm With this parameter you define which

BTSs in the SEG may be used for

GPRS or EGPRS without signal level

measurements. This parameter

defines the signal level compared

to non BCCH layer offset. When thevalue of this parameter is higher

than the value of the parameter non

BCCH layer offset the direct

GPRS access to non BCCH layer

BTS is applied. This is used in

initial channel allocation and

reallocation.







value

Description

bsTxPwrMax

(PMAX1)

BTS 0..30 (dB)

with a step

size of 2

MML

default: 0


maximum transmission power of the

BTS as an attenuation from the peak

power of the TRX. This parameter is

used for frequency bands GSM 800

and GSM 900.

bsTxPwrMax1x00

(PMAX2)

BTS 0..30 (dB)

with a step

size of 2

MML

default: 0


maximum transmission power of the

BTS as an attenuation from the peak

power of the TRX. This parameter is

used for frequency bands GSM 1800

and GSM 1900.

non BCCH layer access threshold

(LAR)

The exception is when the BCCH hasbeen configured to GSM 1900 band in

GSM800/GSM1900 Common BCCH

cell. In that case you define a

threshold value for the downlink

signal level on GSM 1900 layer for

allowing access to GSM 1900 BCCH

layer.

non BCCH layer exit

threshold (LER)

The exception is when the BCCH has

been configured to GSM 1900 band in

GSM800/GSM1900 Common BCCH

cell. In that case you define a

threshold value for the measured

downlink signal level on GSM 1900

layer for a moving MS from GSM

1900 BCCH layer to GSM 800 layer.

non-BCCHLayerOffset

The nonBCCHLayerOffset parameter is the key parameter of the Common

BCCH feature. It is set at BTS level and for each BTS it defines the signal level

difference with respect to the BTS carrying the BCCH channel. In order to

optimise the channel allocation procedure in a multi band segment, a self-

regulation procedure is implemented in such a way that the network automatically

tunes the nonBCCHLayerOffset value for each BTS within a segment.

2.5 Impact on NSS

No impact.



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2.6 Impact on OSS

NetAct support for Common BCCH and Multi BCF features is available in

OSS3.1 ED1 onwards. If this release is not available, it is not recommended toactivate Common BCCH and Multi BCF features in the network. In case features

are activated before OSS3.1 ED1 (or later) is installed, the whole management of

radio network in the sites where Common BCCH and Multi BCF are available,

will not work.

Unified Mediation and Adaptation layer interfaces the managed network and

provides data for the network wide systems. BSS adaptation is based on Q3.

NetAct Radio Access Configurator (RAC)

NetAct Radio Access Configurator (RAC) provides network wide access andtools to configure Common BCCH and Multi BCF features. The related BTS

radio parameters can be managed from NetAct Radio Access Configurator from

OSS3.1 ED1 onwards. In BSC the Common BCCH and Multi BCF management

is handled via Segment. In Radio Access Configurator the segment management

is done using a master BTS definition. For more information, see the NetAct

customer document Maintaining Multi-BCF Sites.

NetAct Administrator

NetAct Administrator offers full support to Common BCCH and Multi BCF

admin tasks, for example:

. Fast download and activation of Common BCCH and Multi BCF SW to

BTSs via Nokia NetAct tools

. Expandable SW archives

. Storages for multiple SW configurations

NetAct Planner

Nokia NetAct Planner release 4.1 includes a set of radio network and planning

feature for Common BCCH and Multi BCF. This allows visibility of Common

BCCH and Multi BCF in radio network planning: creation of Multi BCF master BTSs and Common BCCH allocations. Plans can be completed with Radio

Access Configurator.

NetAct Monitor

Standard Nokia NetAct monitoring applications are used also for monitoring of

Common BCCH and Multi BCF features. All alarms are available in NetAct

monitoring tools.






Reporting for Common BCCH and Multi BCF is done by common Nokia NetAct

reporting tools. Network Doctor utilizes segment as a new measurement object.

Segment replaces in many cases BTSs in reporting:

. Presenting raw counters or KPIs result in Segment_ID level instead of BTS

level with the current ReportBuilder

. Defining the object (for example, segment ID, BTS, etc.) aggregation

method on top of the time aggregation formula in the Formula wizard with

ReportBuilder

. Selecting the Segment ID as hierarchy and Segment ID as summary level

in the dimension selection for report properties

Note that BTS level is still applicable in some cases, although it is in many cases

replaced by segment.

There are also a few new counters in current measurements like HO

measurement. These counters can be seen in Network Doctor report 151:

. Intra Segment success in SDCCH HOs

. Intra Segment success in TCH HOs

. Inter Segment success in SDCCH HOs

. Inter Segment success in TCH HOs

Network Doctor for BSS (optional feature) in ED2 (Network Doctor version3.1.5) utilises segments and the following reports are supported:

. Segment configuration report, 052.

For detailed information on these reports, see NetAct customer document BSS

Network Doctor Reports.

NetAct Tracing

Nokia NetAct Tracing supports Common BCCH and Multi BCF capable Nokia

network elements in OSS3.1 ED1 onwards. TraceViewer offers efficient means totrace mobile equipments or subscribers in GSM and GPRS networks.

TraceViewer does not show any specific counters related to Common BCCH.

Features include real-time troubleshooting and a possibility to monitor the

network functionality and possble problems on a call level. Segment information

is available in Trace reports.



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NetAct Optimizer

Optimizer supports BSS Common BCCH and Multi BCF features. Internally

Optimizer creates Cell objects based on Segment ID and Master BTS flag

information. In geographical map view Common BCCH and Multi BCF Cells

(Segments) are visible entirely; non-segment BTSs are available as earlier. 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 linked to Master BTS in Cell (Segment).

2.7 Impact on Interfaces

2.7.1 Impact on A Interface

Table 7. This table indicates the impact on the A interface.


BSC No impact

MSC No impact

2.7.2 Impact on Abis Interface


BTS No impact

BSC No impact

2.7.3 Impact on Gb Interface


BTS No impact

BSC No impact






2.8 Feature Interoperability

Queuing

Queuing is applied at the segment level. There is no priority between different

mobile types; therefore the mobiles supporting all frequency bands are more

likely to be allocated a channel.

There is no specific reason to vary the values of the parameters

timeLimitCall and timeLimitHandover with respect to the one-layer

network setting.

The value of the parameter maxQueueLength has to be re-setting, considering

that the percentage is evaluated on the total number of TRXs (including all BTSs

of the segment) and the resulting number should be lower than the number of available SDCCH channels on the BCCH serving layer band. This is because

some capacity must be left to services that run on SDCCH only (for example,

SMS).

Some mobiles may be put into a queue even though all the TCH resources of the

segment are not fully utilised (this is the case when the mobile in the queue does

not support the available capacity). In this case it is very important to make sure

that SDCCH capacity is still available for further requests from mobiles

supporting the available TCH capacity. For this reason the margin between

maxQueueLength and the number of SDCCH channels on the BCCH serving

layer band should be greater than before.

(E)GPRS

Each BTS object in a segment has its own GPRS terrritory. The parameters that

are used to define the size of GPRS territory are adjusted in each BTS.

When comparing the TCH load of a segment's BTS with the parameter

BTSLoadInSEG the BSC interpretes RTSLs in GPRS territory as busy channels

(excluding dedicated GPRS resources). This interpretation prevents the GPRS

territory of a single BTS from shrinking unnecessarily, if there are other BTSs in

the segment to which CS calls could be transferred from the BTS in question.

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

For more information about GPRS territories, see GPRS in BSC .



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Pre-emption

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

As in queuing, a pre-emption procedure can occur even though all the TCH

resources of the segment are not fully utilised (this is the case when the mobile

causing a pre-emption does not support the available capacity). The candidate for

forced actions is selected from among the resource types that are supported by the

mobile that initiates the pre-emption procedure. The candidate with the lowest

priority is selected inside the selected frequency bands. Whenever possible, the

BTSs that use the same frequency band as BCCH-BTS are the most preferred

ones. The maximum number of possible calls in a pre-emption queue is 8.

IUO

In the segment environment, the use of Intelligent Underlay-Overlay is a BTS-

specific functionality. Each BTS in a segment can have its own regular and super-reuse layers. The super-reuse layer of a BTS can be accessed only via the regular

layer of the BTS.

Figure 3. IUO frequency groups in GSM900 /GSM1800 Common BCCH

network

Figure 4. IUO frequency groups in GSM800/GSM1900 Common BCCH

network

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 800

regular TRXsGSM 800

super TRXs

GSM 1900

regular TRXsGSM 1900

super TRXs






The target for a super-reuse TCH request is always one BTS (a few TRXs within

the BTS) and not the whole segment as in resource requests in general. The

handover from regular resources to super-reuse resources in a BTS is the same

regardless of whether segment architecture is used or not.

When an IUO handover from a super-reuse TRX to the regular resources of a

BTS is performed, the information on the usability of different resource types in

the segment is decided based on the values of the parameter

nonBCCHLayerOffset in the different BTSs of the segment. As a target, the

BSC accepts the BTSs whose nonBCCHLayerOffset value is less than or

equal to the value of the BTS where the handover was initiated. This is indicated

in the figure Possible handover directions on a segment with dashed-line arrows

going from the super-reuse layer of one BTS to the regular layer of another BTS

in a segment.

The child cell concept is not supported in the BSC in which the segment option isenabled.

Direct Access to super re-use layer is only supported inside the BTS_Object with

the initial SDCCH, which must be in the BCCH band.

To get an accurate estimation of the C/I value of the Common BCCH segment's

non-BCCH frequency band layer, the estimation is based on the measurement of

the BCCH frequency in the segment. The C/I calculation is modified so that the

segment's BCCH measurement result is used instead of the serving TCH

measurement result.



27 (59)




Figure 5. Possible handover directions on a segment

Multi BCF

If the Multi BCF feature is activated with the Common BCCH Control feature,you can configure not only BTSs that use different frequency bands but also

BTSs of different base station types (for example, Talk-family and UltraSite)

within a segment.

Note

This feature requires synchronisation between the cabinets.

For more information, see Overview of implementing Multi BCF in Multi BCF

System Feature Description.

Frequency Hopping

Frequency Hopping is managed at the BTS level.

BTS1

Regular area

Super reuse area

BTS2

Regular area

Super reuse area






The MA list is a band-specific list formed according to the frequency band the

MS is directed to and it is indicated to the MS in the Assignment Command and

in the Handover Command. The Immediate Assignment Command always

includes the MA list of the band on which the segment's BCCH resides.

The CA list is used by MSs to decode Mobile Allocation when frequency

hopping is applied. The broadcast of the CA list to the MSs in the System

Information 1 message only includes the segment's frequencies of the band on

which the BCCH carrier resides. PGSM 900 and EGSM 900 are regarded as

separate frequency bands.

Frequency hopping between different bands of operation is not supported.

Frequencies belonging to different bands used in the same segment are kept apart

from each other by having separate Cell Allocation and Mobile Allocation lists

for each frequency band of the segment.

Baseband hopping is not recommended for any number of TRXs, it is only

recommended in BTS_Object ('sector' in the BTS) that have RTC combiners. For

combinerless sectors and sectors with Wideband combiners Radio Frequency

Hopping or Antenna hopping (available with UltraSite in CX4 / BSS11)

baseband hopping is recommended.

Several hopping groups can be assigned even though there are only resources for

one band in a segment. The hopping groups are formed by grouping the needed

TRXs into one BTS and by having several BTSs of the same band. Each BTS has

hopping parameters of its own: different frequency groups can have, for example,

different MA list lengths and different reuses, and thus different hopping gain.This can be used, for example, to have some good quality TRXs and others with

lower quality within a segment. The idea is that the poorer quality TRXs are only

used to handle high traffic peaks.

ICE+

ICE+ is possible as it was in BSS9 in a segment that consists of only one BTS

object. If it is used in the BCCH BTS_Object of a Common BCCH segment with

several BTS objects, then the direct access functionality of ICE+ is only

supported inside the BTS_Object with the initial SDCCH, which must be in the

BCCH band. ICE+ in a non-BCCH BTS_Object is not supported.

When the Common BCCH feature is active, the

nonBCCHLayerAccessThreshold parameter in the Handover Control

Parameter Handling command group is used for the usability evaluation of the

non-BCCH layer in a segment with resources from different frequency bands. For

this reason, theIntelligent Coverage Enhancement features cannot be used in a

segment with BTSs from both GSM 900/800 and GSM 1800/1900 frequency

bands.



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Extended Cell

Extended Cell in UltraSite is a BSS 11.5, CX4.1 feature; it is not a BSS11 feature.

Extended Cell is available for Talk family.

In a segment environment, only BCCH BTSs can have extended area TRXs. If a

segment has resources from different frequency bands, calls can only be handed

over to a band other than the BCCH serving layer in the normal area. If different

bands are present in the segment, quite a balanced capacity distribution between

normal and extended areas can be obtained by configuring almost all TRXs

belonging to the BCCH BTS as extended.

Directed Retry

As in Queuing, also the Directed Retry or the Intelligent Directed Retry

procedure can be triggered even if all resources of a segment are not completelyin use. Since the Directed Retry procedure reduces SDCCH capacity, the Directed

Retry timers should not be set too high and SDCCH capacity should be

dimensioned with the proper margin, to avoid SDCCH blocking (due to the DR

procedure) for any mobile supporting the available TCH capacity.

DADL/B

The purpose of the Direct Access to Desired Layer/Band feature is to direct traffic

in the call setup phase from the SDCCH of a macro cell/GSM 900/800 cell to a

TCH of a micro cell/GSM 1800/1900 cell whenever possible.

In the segment environment, the DADL/B feature can be used to direct traffic

between segments. The loads are evaluated per segment, adjacency definitions

are between segments, and DADL/B handovers are made between segments. The

feature activation therefore only makes sense in the case of a single-band segment

environment.

AMH

The BSC-controlled traffic-reason handover is a segment level procedure which

includes the related parameters. The loads are evaluated per segment, and the idea

is that the power budget margin is dynamically changed to direct the MSs

hanging around on the segment border to less loaded adjacent segments.

Nevertheless, if each segment is dimensioned to handle the needed capacity (as it

should be with the Common BCCH feature, considering that 3 different bands

can be used and up to 36 TRX objects are allowed in a segment), the traffic

should be smoothed out among the BTSs within a segment, rather than directed to

adjacent segments. Therefore, when the Common BCCH feature is active and the

segments are multi-band, the AMH feature is less beneficial.






Dynamic Hot Spot

The Dynamic Hot Spot control operates on the BTS level. The usability of a

given frequency band is defined by examining the interference of the respective

band in the neighbouring cells. Here PGSM 900 and EGSM 900 are regarded as

one GSM 900 band and the examinations are made accordingly. The dynamic hot

spot algorithm is applied when the number of busy TSLs in the layer where TCH

is requested exceeds the threshold parameter softBlockingStartReg.

Since adjacencies are defined on the segment level, the interfered cells are also

defined at the segment level: all the possible BTSs of an adjacent segment are

examined (layer by layer) if the segment has been defined as an interfered cell.

For the feature to work properly, frequency-hopping groups must be allocated

using the same criteria for all frequency bands. This means that all the layers of a

given segment are interfered by the corresponding layers of the interfering

segment. In the soft blocking evaluation, the contributions from BTSs belongingto the same band are summed up and if different frequency groups are assigned to

BTSs belonging to the same band and same segment, frequency groups should be

assigned in all the interfered segments.

A non-uniform network where one-band segments exist together with multi-band

segments does not affect the performance of the feature.

Dynamic Hot Spot is applied in call attempts and incoming inter-BTSs handovers

(external, internal inter and intra segment), except when TCH is allocated inside a

non-hopping TRX or an internal inter-segment handover is performed because of

bad signal quality.

Minimum acceptable C/N ratio in channel allocation

If the value of the parameter CNThreshold varies between the BTSs of the

same resource type, the BSC selects the highest value for calculation. The

recommendation for a certain resource type in the segment is disabled when the

value is not used even in one of the BTSs of the same resource type.

MS power level optimisation in handover and call setup

If the value of the parameter optimumRxLevUL varies between the TRXs of the

BTSs of the same resource type, the BSC selects the highest value for calculation.The optimum uplink RF signal level for a certain resource type in the segment is

disabled when the value is not used even in one of the TRXs of the BTSs of the

same resource type.



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FACCH Call Setup

FACCH Call Setup means allocating a TCH for the signalling phase of a call in a

SDCCH congestion. Thus, the same restrictions apply for FACCH Call Setup as

for SDCCH allocation: it is limited in the BCCH frequency band.

TRX prioritisation in TCH allocation

The possibility to favour or avoid the BCCH TRX in call assigning has been

maintained to some extent in the segment environment. This is examined after the

BTSs of a segment have been compared on the basis of their loads and their

respective load parameters.

HSCSD

Adding a new frequency band combination into the Common BCCH Controlfunctionality is perfectly transparent from the point of view of the High Speed

Circuit Switched Data feature.

The main change concerning HSCSD is that HSCSD resource allocation is made

according to the capabilities of an MS considering the radio conditions and the

loads of the different resource types. Among the BTSs that the BSC defines as

reasonable, the TCH search is performed so that the HSCSD channel

configuration that best fulfills the request is selected.

The HSCSD feature is BTS-specific.

Shutdown with forced handover

When locking a single BTS of a segment, an intra-cell handover is possible. If a

BCCH-BTS of the segment is in the state locked when another BTS in the SEG is

shut down, only an inter-cell handover is possible. The same applies when the

BCCH-BTS itself is shutting down.

Dual Band

Note

Common BCCH replaces the Dual Band. Dual Band is replaced by Common

BCCH, but is still available for cases where BTS Site & Cell definitions still use

separate BCCHs for each of the bands. Use Common BCCH if possible.

Common BCCH has requirements that have to be taken into account. For

example that the BTS objects of different frequency bands that are combined

within a common BCCH controlled segment have to be co-sited and

synchronised.






2.9 Impact on mobile terminals

Common BCCH requires a multi band capable terminal.

Common BCCH and handover

Common BCCH and channel allocation

SDCCH dimensioning with Common BCCH

Overview of implementing Common BCCH




33 (59)









3 Planning Common BCCH

3.1 Common BCCH and handover

In a Common BCCH segment environment, new types of handovers have been

introduced. Also, handovers between different BTSs can occur inside the samesegment or between different segments. The following handover types have been

added:

. Intra-BTS (intra-segment) handover; equivalent to the old intra-cell

handover

. Inter-BTS intra-segment handover

. Inter-segment internal (intra-BSC) handover

. Inter-segment external (inter-BSC) handover; equivalent to the old external

handover

The inter-BTS handovers can occur within the same frequency layer or between

different frequency layers.

Handover causes

. Power Budget Handover

The standard PBGT (power budget) calculation is applied for an MS on the

PGSM 900, EGSM 900, or GSM 800 layer. If an MS is on the GSM 1800/

1900 layer of the multi band Common BCCH segment, the decision on the

PBGT handover is based on the measurement of the segment's own BCCH

frequency that the MS measures when on the GSM 1800 band. The BCCH

measurements are compared with each other to decide the superiority

between the serving and an adjacent segment.

. Load based TCH handover

In addition to the standard TCH TCH handovers, when the Common

BCCH is active, the BSC can command an additional handover to balance

the load between different frequency bands.



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Planning Common BCCH



During the call setup procedure the load cannot necessarily be kept under

the BTSLoadInSEG limit for each BTS, because not all terminals support

all the resource types. Furthermore, due to their propagation properties, the

GSM 1800/1900 resources may not be available in all TCH allocation

cases.

When deciding on initiating a handover to balance the load between the

BTSs of a segment, the triggering load limit L is defined with the formula:

L = BTSLoadInSEG + ((100 - BTSLoadInSEG )/2)

Even if the BTSLoadInSEG-parameter has been set to value 0, load in the

BCCH BTS has to be over 50% in order to calls are moved to the other

BTS of non BCCH layer. If the BTSLoadInSEG-parameter is set to value

1%..100%, current way of calculation of load limit is used.

Using the adjusted value of BTSLoadInSEG -parameter as a triggeringload limit for handover within segment has changed after loading CD3.0

for 13.13-0 environment. This has an impact on cases where resources on

the BCCH-layer are scarce.

As an improvement, the possibility to trigger an intra cell handover from

the BCCH layer BTS irrespective of the load in the BTS has been

implemented. The value 0 of BTSLoadInSEG-parameter has now a special

meaning. When the operator has set it to value 0, the BSC tries to hand all

calls fullfilling signal strength criterias over from the BCCH layer BTS to

non BCCH layer. This causes that the resources on the BCCH layer are

kept free as far as possible.

Since in GSM900/GSM1800 the main purpose of the handover is to move

the TCH load from the GSM 900 bands to the GSM 1800 band and EGSM

band, respectively, these two bands are the only possible targets (with

priority given to the 1800 band).

In GSM 800/1900, it may be preferable to use a handover that moves the

TCH load from the GSM 1900 band to the GSM 800 band instead of

freeing the TCH for a single-band GSM 1900 mobile.

The BSC checks the load of the GSM 900/800 BTS every time it receives a

TCH request for the segment in question. When the BSC selects target

BTSs for a load based intra cell handover, it only accepts BTSs whose load

is below the respective BTSLoadInSEGvalue.

SDCCH handover

In addition to the standard SDCCH SDCCH handovers, a new inter band (intra-

segment) SDCCH handover has been implemented to avoid long SDCCH

reservations, thus reducing the SDCCH pressure on the BCCH resource layer.






This handover is triggered when the length of an SDCCH reservation on the

BCCH layer equals the value of the intraSegSDCCHHoGuard parameter.

The handover is performed if there are available SDCCH resources outside the

BCCH band and the MS has the required capability.


3.2 Common BCCH and channel allocation

SDCCH allocation procedure

The general process of SDCCH selection (that applies in the case of an SDCCH-

SDCCH intra-BSC handover) is the following:

. BTS selection:

The BTSs where the SDCCH can be allocated are filtered based on the

information on the frequency capability of the accessing MS and on the

usability of radio resources in different frequency bands.

The BTSs are divided into groups according to their frequency band (BTSs

using the BCCH frequency band form one group and BTSs using a

frequency other than the BCCH frequency band form another group).

The SDCCH load of each BTS group is calculated taking into account only

the static SDCCH resources. The channel is allocated from the BTS group

that has the lowest load.

. TRX selection:

Within the selected BTS(s), the TRX that has the lowest channel load

(busy traffic and signalling channels) is selected. In RF hopping , the BTSs

with an RF hopping TRX prioritisation, the priority is given to non-BCCH

TRXs. The SDCCH channel from the BCCH TRX is allocated only if there

are no idle SDCCHs in other TRXs at all.

. RTSL selection:

The RTSL that has the highest number of idle SDCCH channels left is

selected. However, if a signalling channel was last allocated from the same

TRX, another RTSL than last time is allocated, when possible.

If there are no idle static SDCCH resources in the BTSs, dynamic SDCCH

resources are searched for in every BTS group. From all TRXs, the RTSL

which has the least idle dynamic SDCCH channels is selected.



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SDCCH assignment (Immediate Assignment)

In a multi-band Common BCCH segment, the initial SDCCH channel for a call

setup is always allocated in the layer where the segment's BCCH resides.

This is because the capabilities of an accessing MS are not known when the MS

sends the establish indication message. It is not possible to define the usability of

the non-BCCH frequencies of the segment, as the MS only starts sending

measurement reports after it has been moved to a dedicated channel.

Within the BCCH frequency band, the SDCCH to be allocated is selected

according to the algorithm described above.

If there are no idle static or dynamic SDCCH resources in the BTSs, an idle TCH

timeslot is configured as a new temporary SDCCH resource. Dynamic SDCCH

reconfiguration is only applied in the Immediate Assignment phase, not inhandovers.

SDCCH external handover

During inter-BSC handovers, the usability of radio resources in different

frequency bands than the BCCH cannot be defined in the target BSC. If the non-

BCCH layer is regarded as a layer with less coverage (as indicated by the positive

value of the nonBCCHLayerOffset parameter), only BCCH frequency band

resources are used in the SDCCH allocation for an external handover. (If the

BCCH is on GSM 900/800, the EGSM 900 band can also be utilised according to

the MS capabilities.) If the non-BCCH layer is regarded as a layer with morecoverage (as indicated by the negative value of thenonBCCHLayerOffset

parameter), the non-BCCH layer resources can also be used in the SDCCH

allocation for an external handover according to the mobile capabilities.

SDCCH-SDCCH intra-BTS handover

In the case of an intra-BTS handover, the SDCCH allocation differs from the

basic procedure. The SDCCH is trying to be allocated in a TRX other than the

call serving TRX. The channel in the call-serving RTSL is never selected

(therefore the search procedure is started only if a SDCCH RTSL other than the

serving one is defined in the BTS). If the call-serving TRX is blocked, the basic

search procedure is used.

TCH assignment

The basic difference between TCH allocation in a Common BCCH controlled

segment and a single BTS cell is that the target of a TCH request in a segment is a

set of BTSs instead a single BTS. Basically, all existing rules for selecting a TCH

in a single BTS cell are also valid between BTSs in a segment cell. The general

process for TCH selection is as follows:






. BTS(s) selection:

The BTSs where a TCH can be allocated are filtered on the basis of the

information on the frequency capability of the accessing MS and on the

usability of radio resources in different frequency bands.

The BTSs are filtered according to their load. The load calculation is based

on the BTS-specific parameter BTSLoadInSEG. TCHs are assigned from

the BTSs whose load is less than the BTSLoadInSEG value. See chapter

Handover causes.

When each BTS has reached its load limit the allocation continues in those

BTSs where the load is less than the highest load threshold value among

the BTSs.

When the load in all the BTSs has reached the level of the highest load

threshold value among the BTSs, the GSM 1800 band, the EGSM 900, and

PGSM 900 bands are respectively preferred. Therefore the prioritisation

between the frequency layers is applied only in high-load conditions,

where the better GSM 900 resources are saved for the MSs with limited

frequency capability or in the cell border area.

. RTSL(s) selection:

After the primary target group of BTSs for TCH allocation has been

selected, all the idle RTSLs are ranked according to their interference level

and to the interference level recommendation defined in the BTS they

belong to.

If there are several candidate RTLSs with the same interference level, the

TRX prioritisation in TCH allocation is applied: the RTSL is allocated

from the BCCH TRX or from a non-BCCH TRX according to the defined

prioritisation.

If several candidate RTLSs exist after applying the TRX prioritisation in

TCH allocation, the RTSL is allocated from the BTS with the lowest

Circuit Switched load by using the round robin method so that the BTS

allocated the previous time is the last choice.


3.3 SDCCH dimensioning with Common BCCH

Consider the multi-band mobile and the following two scenarios:

Case 1: GSM Network with separated cells GSM 900/800 and GSM 1800/1900



39 (59)




Case 2: Common BCCH GSM Network (GSM 900/800 and GSM 1800/1900

BTSs co-located).

Case 1 Case 2

. 2 TRXs/cell (1% blocking), 8.11 Erl/cell

. Traffic density 25 mErl/subs, 325 subs/cell

. Call establishment time:

SDCCH reservation time 7 sec/call, 1.94 mErl/call,

325 calls/hour/cell x 1.94 mErl/call = 0.631 Erl/cell

(SDCCH)

. Location update (once in 60 minutes), 325 subs/

cell x 1.94 mErl/call = 0.631 Erl/cell (SDCCH)

. SDCCH capacity = 0.631 + 0.631 =1.262 Erl/cell

.

Number of SDCCH channels/cell = 55 SDCCH channels are necessary for each BTS. So a

separated channel configuration is needed for each

BTS (TS0 is dedicated for the BCCH channel and TS

1 for SDCCH channels).

. 4 TRXs in a segment (1% blocking), 20.33 Erl/cell

. Traffic density 25 mErl/subs, 813 subs/cell

. Call establishment time:

SDCCH reservation time 7 sec/call, 1.94 mErl/call,

813 calls/hour/cell x 1.94 mErl/call = 1.58 Erl/Call

(SDCCH)

. Location update (1.4 times in 60 minutes due to

smaller location area compare with 2 TRXs/cell),

813 calls/cell x 1.4 x 1.94 mErl/call = 2.2 Erl/Cell

(SDCCH)

. SDCCH capacity = 1.58 Erl/Cell + 2.2 Erl/Cell = 3.8

Erl/Cell

Number of SDCCH channels = 10. A separated

configuration is needed, with 2 TS for SDCCH on the

BCCH layer.







4 Implementing Common BCCH

4.1 Overview of implementing Common BCCH

Summary

Common BCCH feature is always active if the operator has bought it. It cannot be

activated/disabled with the WOA command.

The following implementation instructions of Common BCCH in Nokia network

are for GSM800 and GSM1900. The same procedure can be applied to

implement other band combinations.

Steps

1. Creating a multiband cell (segment)

2. Moving a BTS from one segment to another existing segment

3. Cancelling the expand of the segment

Further information

. Overview of GSM/EDGE Common BCCH .

. SDCCH dimensioning with Common BCCH .

. NetAct documentation set: Implementing Parameter Plans gives

instructions on how to plan and prepare parameter changes, for example

when bringing new features into use in the GSM and WCDMA networks.



41 (59)

Implementing Common BCCH



4.2 Creating a multiband cell (segment)

Purpose

Create a multiband segment by creating a new GSM 800 BTS to an existing GSM

1900 segment.

Before you start

The preconditions for a multiband segment creation are that the existing segment

has one BTS using the GSM 1900 frequency band that has all TRXs in the WO

state. During the BSC software installation, the system has created a SEG for

each existing BTS. The number of the SEG is the same as the number of the

related BTS, for example BTS-12 => SEG-12.

You can use the create BTS and TRX commands of the BSC MML or NetAct to

create the new BTS.

Steps

1. Create a BTS

a. Create a BTS which uses the GSM 800 frequency band.

With the EEI command you get information about all BTSs and

TRXs of the SEG

EEI:SEG=<seg_id>;

b. Create a BTS (GSM 800) to a segment that has one BTS using the

GSM 1900 frequency band.

Note

Because the segment already exists, the MML does not allow the user to define

cell (segment) specific parameters. Only BTS-specific parameters are allowed.

EQC:BCF=<bcf_id>,BTS=<bts_id>,SEG=<seg_id>:

BAND=800;

c. Check the information about all TRXs of the SEG..

By using the EEI command, you can check the information about all

TRXs of the SEG

EEI:SEG=<seg_id>;






Examples:

a. ZEEI:SEG=44;

SEG-44:

B C F- 0 44 U L TR A S I TE

B T S- 0 44 (G S M 1 9 00 )

T R X - 0 01 (M B C C H C)

TRX-002

b. ZEQC:BCF=44,BTS=77,SEG=44:BAND=800;

c. ZEEI:SEG=44;

SEG-44:


B T S- 0 44 (G S M 1 9 00 )

T R X - 0 01 (M B C C H C)

TRX-002

B T S- 0 77 (G S M 8 0 0)

2. Delete the old BCCH channel

Delete the BCCH channel from the BTS using the GSM 1900 frequency

band.

a. Lock the BTS that uses the GSM 1900 frequency band

EQS:BTS=<bts_id>:L;

b. Lock the BCCH TRX

ERS:BTS=<bts_id>,TRX=<trx_id>:L;

c. Delete the BCCH channel of the BTS and modify it to a TCH

channel

ERM:BTS=<bts_id>,TRX=<trx_id>:CH0=TCHF;

Examples:

a. ZEQS:BTS=44:L;

b. ZERS:BTS=44,TRX=1:L;

c. ZERM:BTS=44,TRX=1:CH0=TCHF;

3. Create a TRX and the BCCH channel

Create a transceiver (TRX) for the new BTS using the GSM 800 frequency

band. Create the BCCH channel.

a. Create the BCCH TRX

ERC:BTS=<bts_id>,TRX=<trx_id>:FREQ=<freq>,



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TSC=<nbr>,PCMTSL=<pcm-tsl>:DNBR=<nbr>:CH0=MBCCHC;

b. Check the information about all TRXs of the SEG

EEI:SEG=<seg_id>;

Examples:

a. ZERC:BTS=77,TRX=3::FREQ=130,TSC=1,PCMTSL=40-1:

DNBR=114:CH0=MBCCHC;

b. ZEEI:SEG=44;


B T S- 0 44 (G S M 1 9 00 )

TRX-001

TRX-002

B T S- 0 77 (G S M 8 0 0)

T R X - 0 03 (M B C C H C)

4. Modify the parameter MsTxpwrMaxGSM(PMAX1) for the new BTS

using the GSM 800 band

Skip this procedure if the default value of the parameter PMAX1 (the

maximum power level that an MS may use in the serving cell) is good

enough.

a. Output BTS parameters

EQO:SEG=<seg_id>:MIS;

b. Modify the MSTxpwrMaxGSM(PMAX1) parameter of the BTS

EQM:SEG=<seg_id>:PMAX1=<value>;

Examples:

a. ZEQO:SEG=77:MIS;

b. ZEQM:SEG=77:PMAX1=35;

5. Define the maximum transmission power for MS accessing the cell

The maximum transmission power that an MS may use when accessing the

BCCH or PCCCH of a cell in which the BCCH is on the GSM 800

frequency band is defined with the parameters MsTxpwrMaxCCH(TXP1)

and GPRSMsTxpwrMaxCCH (GTXP1). The default value for both

parameters is 33 dBm. You can skip this procedure if the default value is

applicable for both parameters.






Note

You can only modify the parameters via segment identification if the segment has

more than one BTS.

Modify the TXP and GTXP of the segment

Modify the MsTxpwrMaxCCH (TXP1) and GPRSMsTxpwrMaxCCH

(GTXP1) parameters.

EQG:SEG=<seg_id>:TXP1=<value>,GTXP1=<value>

Example:

ZEQG:SEG=44:TXP1=35,GTXP1=31;

6. Modify the power control parameters of the segment

Skip this procedure if the power control parameters of the BTS using the

GSM 1900 band values are also applicable to the new BTS using the GSM

800 frequency band. Check that the GSM 800 / GSM 900 frequency band

specific power control parameter bs tx pwr max (PMAX1) has an

applicable value. If not, modify the power control parameters of the

segment.

Note

You can modify the power control parameters only via segment identification if

the segment has more than one BTS. The new value is set for all BTSs of the

segment.

a. Output the power control parameters

EUO:SEG=<seg_id>;

b. Modify the power control parameters

Modify the PMAX (bs txpwr max) parameter.

EUG:SEG=<seg_id>:PMAX1=<value>;

Examples:



45 (59)




a. ZEUO:SEG=44;

b. ZEUG:SEG=44:PMAX1=10;

7. Define the signal level difference by using the parameternonBCCHLayerOffset

Define the signal level difference between a BTS without the BCCH TRX

and the BCCH BTS of the segment.

Modify the value of the nonBCCHLayerOffset parameter. When

creating a BTS, the default value is 0 dBm.

EQM:BTS=<bts_id>:NBL=<value>;

Example:

ZEQM:BTS=44:NBL=5;

Note

Parameters BS TX pwr max (PMAX) and BS TX pwr max 1x00 (PMAX2)

identify the maximum transmission power of the BTS as an attenuation from the

peak power of the TRX and have to be taken into account when defining the

value for parameter nonBCCHLayerOffset (NBL).

Note

The parameter nonBCCHLayerOffset (NBL) is used to indicate how much

weaker the signal level of a BTS is when compared to that of the BCCH BTS.

Because of this, the value of the parameter must always be set to 0 in the BCCH

BTS. A positive value of the NBL in a BTS indicates a signal level lower than in

the BCCH BTS and prevents the SDCCH allocation for call setups and external

handovers in that BTS.

8. Define the load limit for a BTS






Define the load limit for a BTS with the parameter LSEG

(BTSLoadInSEG). You can determine separate LSEGs for all BTSs of

the segment. LSEG is used in controlling the load distribution between

different BTSs in a segment. The default value when creating a BTS is

70%. If you want to change it, use the command EQM.

Modify the value of the BTS load in SEG parameter

EQM:BTS=<bts_id>:LSEG=<value>;

Example:

ZEQM:BTS=77:LSEG=50;

9. Define the threshold value for the estimated downlink signal level on

the non-BCCH frequency layer

Define the threshold value for a segment with the parameter

nonBCCHLayerAccessThreshold (LAR).

LAR is a threshold value for the estimated downlink signal level on the

non-BCCH frequency layer of the segment for moving an MS from the

BCCH frequency layer to the non-BCCH frequency layer. The default

value is 90 dBm. If you want to change it, use the command EHS.

Modify the value of the nonBCCHLayerAccessThreshold parameter

EHS:SEG=<seg_id>:LAR=<value>;

Example:

ZEHS:SEG=44:LAR=-80;

10. Define the threshold for handing an MS over from the non-BCCH

frequency layer to the BCCH frequency layer

Define the threshold for a segment with the parameters

nonBCCHLayerExitThreshold (LER) ,nonBCCHLayerExitThresholdpx (LEP), and

nonBCCHLayerExitThresholdnx (LEN).



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LER is a threshold value for the measured downlink signal level on the

non-BCCH frequency layer for handing an MS over from the non-BCCH

frequency layer to the BCCH frequency layer. LEP and LEN can be used

to define how many of the measurement reports must be below the LER to

trigger the handover. The default value for LER is

95 dBm, the default

value for LEP is 1, and the default value for LEN is 1. If you want to

change the values, use the command EHS.

Handover from the non-BCCH frequency layer to the BCCH frequency

layer is made only if the BCCH frequency layer of the segment has more

coverage than the non-BCCH frequency layer. These three parameters are

used by the BSC only when the BCCH frequency layer of the segment has

more coverage than the non-BCCH frequency layer. Otherwise they are

ignored.

Modify the non-BCCHLayerExitThreshold parameters

EHS:SEG=<seg_id>:LER=<values>,LEP=<value>,LEN=<value>;

ZEHS:SEG=44:LER= 90,LEP=3,LEN=5;

11. Modify the power control parameters of the segment

Skip this procedure if the power control parameters of the BTS using the

GSM 1900 band values are also applicable to the new BTS using the GSM

800 frequency band. Check that the GSM 800 / GSM 900 frequency band

specific power control parameter bs tx pwr max (PMAX1) has anapplicable value. If not, modify the power control parameters of the

segment.

Note

You can modify the power control parameters only via segment identification if

the segment has more than one BTS. The new value is set for all BTSs of the

segment.

a. Output the power control parameters

EUO:SEG=<seg_id>;

b. Modify the power control parameters

Modify bs tx pwr max (PMAX1) parameter.

EUG:SEG=<seg_id>:PMAX1=<value>;






Examples:

a. ZEUO:SEG=44;

b. ZEUG:SEG=44:PMAX1=10;

12. Create adjacent cells

Create more adjacent cell information, if needed. You can create adjacent

cell information with the EAC command, but if the segment has more than

one BTS you have to use segment identification as a parameter instead of

BTS identification.

a. Create an adjacent cell for a segment that has more than one BTS

and is under another BSC

EAC:SEG=<seg_id>::LAC=<nbr>, CI=<nbr>:NCC=<nbr>,

BCC=<nbr>,FREQ=<nbr>;

b. Create an adjacent cell for a segment that has more than one BTS

and is under the same BSC

EAC:SEG=<seg_id>::ASEG=<aseg_id>;

Examples:

a. ZEAC:SEG=44:LAC=199,CI=39:NCC=1,BCC=1,FREQ=131;

b. ZEAC:SEG=44::ASEG=99;

13. Delete an adjacent cell of the segment

In the Common BCCH feature, the BCCH frequency of the segment itself

is added among the BCCH frequencies that the MS should measure when

on the non-BCCH frequency band of the multiband segment. This leads to

the following restriction: a segment can have only 31 adjacent cells.

If the inter-system handover feature is used with the Common BCCH

Control feature then the maximum number of adjacent cells is restricted to

30. Skip this procedure if the segment does not have 32 or 31 adjacent

cells. Otherwise remove one or two adjacent cells of the segment.

Delete the adjacent cell

EAD:SEG=<seg_id>::ASEG=<aseg_id>;

Example:

ZEAD:SEG=44::ASEG=88;



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14. Modify the BA list <option>

In the Common BCCHl feature, the BCCH frequency of the segment itself

is added among the BCCH frequencies that the MS should measure when

the Common BCCH feature is activated. This leads to the following

restriction: there can be only 31 frequencies in a BA list.

If the Inter-System Handover feature is used with the Common BCCH

feature, the maximum number of frequencies in a BA list is restricted to 30.

Skip this procedure if the BA list is not used or if the BA list does not have

32 or 31 BCCH frequencies. Otherwise remove one or two BCCH

frequencies from the BA list (BCCH frequency list).

a. Output the BA list usage parameters

EQO:SEG=<seg_id>:BCC;

b. Remove one BCCH frequency from the BA-list

EBM:<id_nbr>,<function>:<freq>;

Examples:

a. ZEQO:SEG=44:BCC;

b. ZEBM:15,R:140;

15. Create a BA list and attach it to a segment <option>

Skip this procedure if BA lists (BCCH frequency lists) are not used.

a. Create a BA list

Note

If this BA list is going to be used for a segment which has more than one

frequency band in use, the type (frequency band) of the BA list must be MULTI.

EBC:<id_nbr>,MULTI:

<frequency>&<frequency>&<frequency>;

b. Attach the BA list to the segment

EQB:SEG=<seg_id>:IDLE=<ba_id>;

Examples:






a. ZEBC:10,MULTI:150&160&170;

b. ZEQB:SEG=44:IDLE=10;

16. Control the BTS states

The segment object has neither an operational nor an administrative state,

so you must unlock the BTSs of the segment one by one. The BCCH BTS

must be unlocked first. When you unlock a non-BCCH BTS, then the

BCCH TRX of the segment must be in the administrative state WO.

a. Unlock the BCCH TRX

ERS:BTS=<bts_id>,TRX=<trx_id>:U;

b. Unlock the BTS containing the BCCH TRX

EQS:BTS=<bts_id>:U;

c. Unlock the TRXs of the BTS using the GSM 1900 frequency band


d. Unlock the BTS using the GSM 1900 frequency band

EQS:BTS=<bts_id>:U;

e. Unlock the BCF

EFS:<bcf_id>:U;

Examples:

a. ZERS:BTS=77,TRX=3:U;

b. ZEQS:BTS=77:U;

c. ZERS:BTS=44,TRX=1:U;

ZERS:BTS=44,TRX=2:U;

d. ZEQS:BTS=44:U;

e. ZEFS:44:U;

17. Check the postcondition

After unlocking, all TRXs of the segment are in the WO state. A call

should be possible via both BTSs. Synchronized handovers are used

between the BTSs. The system has set synchronized handovers on by

default.

Get information about all TRXs of the SEG

With the EEI command you get information about all TRXs of the SEG.

The system outputs both BTSs and all TRXs of the segment.



51 (59)




EEI:SEG=<seg_id>;

Example:

ZEEI:SEG=44;

Further information

For an overview, see Overview of implementing Common BCCH

4.3 Cancelling the expand of the segment

Purpose

You can move either the BTS using the GSM 800 frequency band or the BTS

using the GSM 1900 frequency band to a new, separate segment. If you want to

move the BTS, which has the BCCH TRX, you must first delete the BCCH

channel because moving a BTS containing a BCCH TRX is not allowed. All

BTSs of the old segment must be in the locked state. For an overview, see

Overview of Common BCCH implementation.

Steps

1. Lock the segment's BTSs and delete its BCCH channel

a. Lock both BTSs and the BCCH TRX

EQS:BTS=<bts_id>:L;

EQS:BTS=<bts_id>:L;


b. Delete the BCCH channel and modify it to a TCH channel

ERM:BTS=<bts_id>,TRX<trx_id>:CH0=TCHF;

Examples:

a. ZEQS:BTS=44:L;

ZEQS:BTS=77:L;

ZERS:BTS=77,TRX=3:L;

b. ZERM:BTS=77,TRX=3:CH0=TCHF;

2. Move the BTS using the GSM 800 frequency band to its own segment

Move the BTS to a new segment






EQU:BTS=<bts_id>:SEG=<seg_id>:CI=<nbr>:NCC=<nbr>,

BCC=<nbr>:MCC=<nbr>,MNC=<nbr>,LC=<nbr>;

For example:

Move base station BTS-77 to segment SEG-88. Segment-specific

parameters must be defined for the new segment.

ZEQU:BTS=77:SEG=88:CI=5:NCC=1,BCC=1:MCC=1,MNC=1,

LAC=15;

3. Define a BCCH TRX for the BTSs using the GSM 1900 and GSM 800

frequency bands

a. Lock a TRX of the BTS using the GSM 1900 frequency band


b. Define the BCCH channel to the TRX of the BTS using the GSM

1900 frequency band

ERM:BTS=<bts_id>,TRX=<trx_id>:CH0=MBCCH;

c. Define the BCCH channel to a TRX of the BTS using the GSM 800

frequency band

ERM:BTS=<bts_id>,TRX=<trx_id>:CH0=MBCCH;

Examples:

a. ZERS:BTS=44,TRX=1:L;

b. ZERM:BTS=44,TRX=1:CH0=MBCCHC;

c. ZERM:BTS=77,TRX=3:CH0=MBCCHC;

4. Define the maximum transmission power for an MS accessing the cell

for both segments



frequency band is defined with the parameters MsTxpwrMaxCCH 1x00

(TXP2) and GPRS MsTxpwrMaxCCH 1x00 (GTXP2). The default value for both parameters is 30 dBm.



frequency band is defined with the parameters MsTxpwrMaxCCH

(TXP1) and GPRS MsTxpwrMaxCCH (GTXP1). The default value for

both parameters is 33 dBm.



53 (59)




You can skip this procedure if the default values are applicable for both

segments.

Note

You can modify the parameters only via segment identification if the segment has

more than one BTS.

a. Modify the TXP2 and GTXP2 of the segment in which the BCCH is

on the GSM 1900 frequency band

EQG:SEG=<seg_id>:TXP2=<value>,GTXP2=<value>;

b. Modify the TXP1 and GTXP1 of the segment in which the BCCH ison the GSM 800 frequency band

EQG:SEG=<seg_id>:TXP1=<value>,GTXP1=<value>;

Examples:

a. ZEQG:SEG=44:TXP2=30,GTXP2=30;

b. ZEQG:SEG=88:TXP1=33,GTXP1=33;

5. Define HOC, POC, and ADJ parameters for the BTS that was moved

Modify the power control parameter values and handover control values,

and create adjacent cells for the BTS that was moved. This must be done

because the power control (POC), handover control (HOC), and

adjacencies do not follow the moved BTS to the new segment. You have to

define the POC, HOC, and any adjacencies needed for the new segment

like in BTS creation.

You can now modify the power control and handover control parameters

via segment identification or via BTS identification because the segment

that has the BTS that was moved only has one BTS.

a. Create power control parameters

Create power control parameters for the new segment by using

either SEG or BTS identifier.

EUC:SEG=<seg_id>;

or

EUC:BTS=<bts_id>;






b. Create handover control parameters

Create handover control parameters for the new segment by using

either the SEG or BTS identifier.

EHC:SEG=<seg_id>;

or

EHC:BTS=<bts_id>;

c. Create an adjacent cell

Create an adjacent cell for the new segment. The adjacent cell is

under the same BSC. You can use either SEG or BTS identifier.

EAC:SEG=<seg_id>::ABTS=<bts_id>;

or

EAC:BTS=<bts_id>::ABTS=<bts_id>;

Examples:

a. ZEUC:SEG=88;

or

ZEUC:BTS=77;

b. ZEHC:SEG=88;

or

ZEHC:BTS=77;c. Create adjacent cell BTS-44 for SEG-88.

ZEAC:SEG=88::ABTS=44;

or

ZEAC:BTS=77::ABTS=44;

6. Control the BTS states

The segment object has neither an operational nor an administrative state,

so you must unlock the BTSs of the segment one by one. The BCCH BTS

must be unlocked first. When you unlock a non-BCCH BTS the BCCHTRX of the segment must be in the administrative state WO.

a. Unlock the BCCH TRX of the BTS that was moved


b. Unlock the BTS that was moved

EQS:BTS=<bts_id>:U;



55 (59)




c. Unlock the BCCH TRX of the BTS using the GSM 1900 frequency

band


d. Unlock the BTS using the GSM 1900 frequency band

EQS:BTS=<bts_id>:U;

Examples:

a. ZERS:BTS=77,TRX=3:U;

b. ZEQS:BTS=77:U;

c. ZERS:BTS=44,TRX=1:U;

d. ZEQS:BTS=44:U;

Further information

For an overview, see Overview of implementing Common BCCH

4.4 Moving a BTS from one segment to another existing segment

Purpose

In this case you move a BTS from the old segment to a new existing segment. AllBTSs in the old segment and in the new segment must be in the locked state.

Moving a BTS containing the BCCH TRX is not allowed. The BTS that was

moved starts to use the new segment's parameters. After moving the BTS you

must unlock all BTSs of the old and the new segment.

Note

When you combine two segments together, move all BTSs of one segment to a

new existing segment. After moving all BTSs the old segment does not exist any

more.

Note

TheGPRS has to be disabled in all BTSs in both segments when moving a BTS

from one segment to another.






Steps

1. Lock all BTSs in the old and the new segment

You are moving a BTS from a segment which has two BTSs to a new

existing segment which has one BTS. The BCCH TRX is not under the

BTS which is going to be moved.

Note

First you must lock all BTSs of both segments.

a. Get information about all BTSs and TRXs of both segments

EEI:SEG=<seg_id>;

EEI:SEG=<seg_id>;

b. Lock all BTSs of the old segment

EQS:BTS=<bts_id>:L;;

EQS:BTS=<bts_id>:L;

c. Lock all BTSs of the new segment

EQS:BTS=<bts_id>;

Examples:

a. ZEEI:SEG=33;

SEG-33:


B T S- 0 33 (G S M 8 0 0)

T R X - 0 01 (M B C C H C)

TRX-002

B T S- 5 5 (G S M 8 0 0)

TRX-3

ZEEI:SEG=66;

SEG-66:


B T S- 0 66 (G S M 8 0 0)

T R X - 0 01 (M B C C H C)

TRX-002



57 (59)




b. ZEQS:BTS=33:L;

ZEQS:BTS=55:L;

c. ZEQS:BTS=66:L;

2. Move the BTS from the old segment to the new existing segment

Move the BTS by using the EQU command.

EQU:BTS=<bts_id>:SEG=<seg_id>;

This is an example:

Move BTS-55 to the new existing segment SEG-66.

ZEQU:BTS=55:SEG=66;

3. Unlock all BTSs in the old and the new segment

a. Unlock the BTS of the old segment

EQS:BTS=<bts_id>:U;

b. Unlock all BTSs of the new segment

Note

You must first unlock the BTS that has the BCCH TRX.

EQS:BTS=<bts_id>:U;

c. Get information about all BTSs and TRXs of both segments

With the EEI command you get information about all BTSs and

TRXs of both segments.

EEI:SEG=<seg_id>;

Examples:

a. ZEQS:BTS=33:U;

b. ZEQS:BTS=66:U;

ZEQS:BTS=55:U;

c. ZEEI:SEG=33;






SEG-33:


B T S- 0 33 (G S M 8 0 0)

T R X - 0 01 (M B C C H C)

TRX-002

ZEEI:SEG=66;

SEG-66:


B T S- 0 66 (G S M 8 0 0)

T R X - 0 01 (M B C C H C)

TRX-002

B T S- 5 5 (G S M 8 0 0)

TRX-3

Further information

For an overview, see Overview of implementing Common BCCH .


Documents

Common BCCH System Feature