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21 Co-BCCH CellAbout This Chapter
21.1 Overview
This topic describes the overview of the co-BCCH cell. The co-BCCH cell adopts the dual-band
technique, featuring expanded network capacity and minimized handover occurrences. For
example, the cell capacity is expanded and the handover times decreases in the dual-band
network with the co-BCCH cells
21.2 Availability
This topic describes the availability of the co-BCCH cell. The realization depends on the
cooperation of related NEs, software and BTS hardware configuration.
21.3 Impact
This topic describes the impact of the co-BCCH cell on other features.
21.4 Technical Description
This topic describes the technical description of the co-BCCH cell. The co-BCCH technology
consists of channel assignment and handover.
21.5 Capabilities
None.
21.6 Implementation
This topic describes the implementation of the co-BCCH cell. The implementation includes thescenarios analysis, configuration preparation, configuration and deactivation.
21.7 Maintenance Information
This topic describes the maintenance information about the co-BCCH cell. The maintenance
information consists of the performance counters related to the co-BCCH cell.
21.8 References
This topic describes the references of the co-BCCH cell. The references refer to the co-BCCH
description documents written by related standard- making organizations. For details about the
features of the co-BCCH, refer to the following documents:
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21.1 Overview
This topic describes the overview of the co-BCCH cell. The co-BCCH cell adopts the dual-band
technique, featuring expanded network capacity and minimized handover occurrences. For
example, the cell capacity is expanded and the handover times decreases in the dual-band
network with the co-BCCH cells
Definition
The co-BCCH cell refers to the cell where both the GSM900 and DCS1800 TRXs exist. In a
dual-band network, a dual-band MS can use frequencies in either the GSM900 band or the
DCS1800 band to make calls. A single-band MS can use frequencies on the related band to make
calls.
Purposes
The co-BCCH cell is used to solve the continuous coverage and sparse coverage problems in
hot spots.
Constructing dual-band network is a trend due to the rapid increase of mobile users. The dual-
band network construction has the following three networking modes:
l MSC independent networking
l Co-MSC and independent BSC networking
l Co-BSC networking
The advantages of constructing the dual-band network with co-BCCH cells are as follows:
l The capacity of the cell is expanded and the occurrences of cell reselection for the MS are
reduced.
For example, a site should be configured with a GSM900 cell and a DCS 1800 cell. Each
cell is configured with two TRXs. You can get the data as shown in Table 21-1 when
querying the ERLANG B.
Table 21-1 Data in ERLANG B
Networking
Mode
BCCHNumber
SDCCHNumber
TCHNumber
Call LossRate
Traffic Volume
Common
dual-band
network
2 2 28 2% 16.40 ERL
Dualband
network in
co-BCCH
cells
1 2 29 2% 21.04 ERL
l The handover occurrences between cells decreases.
When the MS initiates a switchover request, the MS is switched to the channels on the otherfrequency bands in the cell.
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l The number of the CC TRX decreases and the number interferences caused by the CC TRX
decreases.
The system assigns channels on different frequency bands to the MS according to the receive
level, receive quality and TA value. Thus, the maximum cell coverage is reached. In addition,
as the coverage is expanded in the underlaid subcell and the traffic is absorbed by the overlaidsubcell, the capacities of the underlaid subcell and overlaid subcell in the cell are balanced.
Terms
Terms Definition
M criteria
determination
Indicates that only the adjacent cells that the receive level is higher
than the lowest receive level can be listed in the candidate cells list.
The serving cells and adjacent cells are sequenced according to the
level.
ERLANG B Indicates the relation among the number of common channels, call
loss rate and busy-hour traffic volume. The ERLANG B is
developed from the ERLANG call loss formula.
Abbreviation
Abbreviation Full Spelling
BCCH Broadcast control channel
SDCCH Stand-alone dedicated control channel
PBGT Power budget
BQ Bad quality
MR Measurement report
TA Timing advance
21.2 Availability
This topic describes the availability of the co-BCCH cell. The realization depends on thecooperation of related NEs, software and BTS hardware configuration.
Network Elements Involved
Table 21-2 lists the network elements involved in the co-BCCH cell.
Table 21-2 Network elements involved in the co-BCCH cell
MS BTS BSC MSC MGW SGSN GGSN HLR
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MS BTS BSC MSC MGW SGSN GGSN HLR
NOTE
l : not involved
l : involved
Software Releases
Table 21-3 lists the software releases supported by the GBSS NEs involved in the co-BCCH
cell.
Table 21-3 GBSS products and related software releases
Product Version
BSC BSC6000 V900R001C01 and later releases
BTS BTS2X All releases
BTS3001C All releases
BTS3002C All releases
BTS3X All releases
Double-transceiver BTSs All releases
MiscellaneousThe BTS hardware configuration has the following restrictions:
l Number of TRXs
The number of the GSM900 TRXs and DCS1800 TRXs should be less than or equal to
four in a co-BCCH cell. If the number exceeds four, there must be enough antenna output
ports and modes of antennas. The coverage of the TRXs on the same frequency band should
be the same in the installation of antennas.
l Antenna types and azimuth
If the GSM900 TRX and the DCS1800 TRX use the same antenna, the dual-band
antenna is adopted. If the GSM900 TRX and the DCS1800 TRX use different antennas, both the dual-band
antenna and the single-band antenna can be adopted. When the sing-band antenna is
adopted, the azimuth of the antenna used in the GSM900 TRX and the DCS1800 TRX
in the same cell should be the same.
l Type of the combiner
As combiners do not support these two TRXs at the same time, the GSM900 TRX and the
DCS1800 TRX should use different combiners.
l Combination mode
The combination mode of the TRXs on the same frequency band in the same cell should
be the same. Otherwise, the transmit power levels of the TRXs on the same frequency bandin the same cell are not consistent, and the coverage of these TRXs are not the same. Thus,
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the co-BCCH cell cannot be enabled in this cell because of 3-layer (or more) concentric
cell.
21.3 ImpactThis topic describes the impact of the co-BCCH cell on other features.
Impact on System Performance
None
Impact on Other Features
The co-BCCH cell and the dual-timeslot cell are mutually exclusive.
21.4 Technical DescriptionThis topic describes the technical description of the co-BCCH cell. The co-BCCH technology
consists of channel assignment and handover.
21.4.1 GSM900/DSC1800 Co-BCCH Cell Channel Assignment
This topic describes the channel assignment of the GSM900/DSC1800 co-BCCH cell. The
channel assignment strategy depends on the frequency band supported by the MS and follows
the channel assignment algorithm of the concentric cell.
21.4.2 GSM900/DCS1800 Co-BCCH Cell Handover
This topic describes the GSM900//DCS1800 co-BCCH cell handover. The handover is
performed based on the concentric cell handover algorithm.
21.4.1 GSM900/DSC1800 Co-BCCH Cell Channel Assignment
This topic describes the channel assignment of the GSM900/DSC1800 co-BCCH cell. The
channel assignment strategy depends on the frequency band supported by the MS and follows
the channel assignment algorithm of the concentric cell.
The GSM900/DCS1800 co-BCCH cell is realized based on the concentric cell theory. The
GSM900 TRX is configured in the underlaid subcell to expand the coverage. The DCS1800
TRX is configured in underlaid subcell to absorb the traffic volume.
Thus, the channel assignment of the co-BCCH cell should follow the channel assignment
algorithm of the concentric cell. Before the channel assignment, the system determines the
capability of the ms to support the frequency band. If the MS supports both the GSM900 and
DCS1800 frequency bands, the channel assignment follows the channel assignment algorithm
of the concentric cell. If the MS does not support both of them, only the underlaid subcell channel
is assigned to the MS. The related channel assignment technologies are described in the following
part.
Immediate Assignment
In the immediate assignment procedure, the BSC does not obtain any information about the MS.
To ensure the normal conversation through the MS, the BSC adopts the preferred channel
assignment strategy of the GSM900 frequency band TRX. That is, the BSC selects the channelof the underlaid subcell for the assignment.
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Assignment
In the assignment procedure, the channel assignment is related to the MS Classmark 3. The
details are as follows:
l If the BSC does not obtain the MS Classmark 3 or the MS Classmark 3 indicates that theMS supports only the GSM900 TRX, the BSC selects only the channel of the underlaid
subcell TRX for assignment.
l If the MS Classmark 3 indicates that the MS supports both the GSM900 and DCS1800
frequency bands TRXs, the BSC assigns the channel of the overlaid or underlaid subcell
according to Assign Optimum Layer.
Incoming Internal Inter-Cell Handover
In the incoming internal inter-cell handover procedure, the channel assignment is related to the
MS Classmark 3. The details are as follows:
l If the BSC does not obtain the MS Classmark 3 or the MS Classmark 3 indicates that the
MS supports only the GSM900 TRX, the BSC selects only the channel of the underlaid
subcell TRX for assignment.
l If the MS Classmark 3 indicates that the MS supports both the GSM900 and DCS1800
frequency bands TRXs, the BSC assigns the channel of the overlaid or underlaid subcell
according to Pref. Subcell in HO of Intra-BSC.
Incoming External Inter-Cell Handover
In the incoming external inter-cell handover procedure, the channel assignment is related to the
MS Classmark 3. The details are as follows:
l If the BSC does not obtain the MS Classmark 3 or the MS Classmark 3 indicates that the
MS supports only the GSM900 TRX, the BSC selects only the channel of the underlaid
subcell TRX for assignment.
l If the MS Classmark 3 indicates that the MS supports both the GSM900 and DCS1800
frequency bands TRXs, the BSC assigns the channel of the overlaid or underlaid subcell
according to Incoming-to-BSC HO Optimum Layer.
21.4.2 GSM900/DCS1800 Co-BCCH Cell Handover
This topic describes the GSM900//DCS1800 co-BCCH cell handover. The handover isperformed based on the concentric cell handover algorithm.
Neighboring Cell Selection
No matter what subcell the MS is located, the actual receive levels of the serving cell and the
neighbor cell are sequenced according to the M criteria determination. When the MS is located
in the overlaid subcell, the underlaid subcell is procedureed as a special neighbor cell.
Enhanced Concentric Cell Handover
The underlaid subcell in the concentric cell provides a good voice quality. Thus, the system canmaximize the usage rate of the underlaid subcell.
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The handover from the underlaid subcell to the overlaid subcell occurs when the traffic volume
in the underlaid subcell is high, the signal level and quality of the MS is high, and the TA of the
MS is low. In addition, the following conditions must be met at the same time:
l Downlink receive level UtoO HO Received Level Threshold
This condition is controlled by the RX_LEV for UO HO Allowed.
l Downlink receive quality < RX_QUAL Threshold
This condition is controlled by the RX_QUAL for UO HO Allowed.
l TA < (TA Threshold - TA Hysteresis)
This condition is controlled by the TA for UO HO Allowed.
l Traffic load in the underlaid subcell > Traffic Threshold of Underlay
This condition is controlled by the Underlay HO Step Period(s) and Underlay HO Step
Level.
The handover from the overlaid subcell to the underlaid subcell occurs when receive level orreceive quality or TA of the MS is low. That is, the handover occurs in one of the following
conditions:
l Downlink receive level < OtoU HO Received Level Threshold
This condition is controlled by the RX_LEV for UO HO Allowed.
l Downlink receive quality RX_QUAL Threshold
This condition is controlled by the RX_QUAL for UO HO Allowed.
l TA (TA Threshold - TA Hysteresis)
This condition is controlled by the TA for UO HO Allowed.
l In the neighbor cell sequencing, the priority of the serving cell is the highest.
If the priority of the serving cell is not the highest, the MS is handed over to the other neighbor
cells.
Inter-Cell Handover
Besides in the PBGT handover decision algorithm, the actual receive level of the cell is used in
all the handover decision algorithms.
The PBGT handover decision algorithm involves the receive level of the underlaid subcell. The
PBGT handover algorithm calculates the path loss among the neighbor cells at the same levelto help make the handover decision. As the signal level fading of the overlaid subcell DCS1800
TRX in the co-BCCH subcell is fast, If the handover decision is made according to the actual
receive level in the overlaid subcel, the decision is not proper compared with that of other cells.
To ensure the accuracy of the PBGT handover decision result, the decision should be made
according to the receive level in the underlaid subcell.
21.5 Capabilities
None.
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21.6 Implementation
This topic describes the implementation of the co-BCCH cell. The implementation includes the
scenarios analysis, configuration preparation, configuration and deactivation.
21.6.1 Configuration Principles
This topic describes the configuration principles of the co-BCCH cell.
21.6.2 Preparations for the Configuration
This topic describes the preparations for configuring the co-BCCH cell. Before the configuration,
you should be familiar with the related information as the reference of parameters configuration.
21.6.3 Risk Analysis of the Configuration Scenarios
This topic describes the risk analysis of the configuration scenarios. The risk analysis consists
of the risk in common and special scenarios.
21.6.4 Configuring the Co-BCCH Cell
This topic describes how to configure the co-BCCH cell. You should configure co-BCCH
parameters on the BSC6000 Local Maintenance Terminal.
21.6.5 Deactivating the Co-BCCH Cell
This topic describes how to deactivate the co-BCCH cell. You can deactivate the co-BCCH cell
on the BSC6000 Local Maintenance Terminal.
21.6.1 Configuration Principles
This topic describes the configuration principles of the co-BCCH cell.
The co-BCCH cell consists of the overlaid subcell and the underlaid subcell. The overlaid subcell
is configured with the DCS1800 TRX while the underlaid subcell is configured with the GSM900
TRX.
NOTE
The path loss of the DCS1800 TRX is large. The signal power of the DCS1800 is 15 dB less than that of
the GSM900 in about 0.5 to 1 km.
Configure the co-BCCH subcell based on the following principles:
l Do not assign the overlaid subcell channel to the call, and do not assign the inter-cell
handover request to the overlaid subcell. In addition, do not assign the calls covered by the
DCS1800 TRX forcibly to the overlaid subcell.
l Assign the traffic volume in the underlaid subcell properly to avoid the traffic imbalance
between the overlaid subcell and the underlaid subcell.
l Configure the BCCH in the GSM900 TRX. The priorities of the TRX types from high to
low are: P-GSM, E-GSM and R-GSM.
l Configure the SDCCH, PDCH and BCCH in the same TRX.
l The frequency hopping between the GSM900 and DCS1800 TRXs is not supported. Only
the frequency hopping within the same frequency band is supported.
l Avoid multi-layer concentric cell because of inconsistent combination mode of the TRXs
in the same frequency band. Otherwise, the KPI measurements such as handover successrate, assignment success rate are influenced.
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21.6.2 Preparations for the Configuration
This topic describes the preparations for configuring the co-BCCH cell. Before the configuration,
you should be familiar with the related information as the reference of parameters configuration.
You should be familiar with the following information about the cell:
l User distribution and traffic volume in the coverage area
l Percentage of the coverage of the DCS1800 TRX in the coverage of the entire cell
l Percentage of the coverage of the GSM900 TRX in the coverage of the entire cell
l Number of the GSM900 TRXs for supporting all the traffic in the cell
l Number of the GSM900 and DCS1800 TRXs in a co-BCCH cell, and the congestion feature
and the interference of the GSM900 frequency reuse
Pay attention to the following in the network planning:
l Limit on the TRXs numberYou should follow the relation formula to avoid the GSM900 cell congestion in busy hours:
Number of GSM900 TRXs (Number of the DCS1800 TRXs - 1)
l Limit on the neighbor cell
The co-BCCH cell can not be adjacent to the single-frequency GSM900 cell and single-
band DCS1800 cell. Otherwise, it becomes difficult to balance the traffic volume
distribution.
21.6.3 Risk Analysis of the Configuration Scenarios
This topic describes the risk analysis of the configuration scenarios. The risk analysis consists
of the risk in common and special scenarios.
Two TRXs with different coverage capabilities are configured in the same cell in the co-BCCH
cell. Thus, the user should assign the traffic of the overlaid and underlaid subcells properly in
order not to influence the network performance counters. The traffic volume assignment of the
overlaid and underlaid subcells is influenced by the number of the TRXs in the overlaid and
underlaid subcells, and the actual coverage of the overlaid and underlaid subcells (distance
between sites).
Risk Analysis of Common Scenarios
Table 21-4 shows the risk analysis of common scenarios.
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Table 21-4 Risk analysis of common scenarios
No.
ScenarioDescription
Risk Scenario Analysis Solution
1 The distancebetween sites is
within 800 meters.
None
In the coverage area of a co-BCCH cell, the coverage of
the DCS1800 and GSM900
TRXs is similar. The
handover from the underlaid
subcell to the overlaid
subcell will not fail
regardless of where the MS
is located.
None.
2 l The distance
between sites is
from 800 metersto 1,600 meters.
l The number of
TRXs in the
underlaid
subcell is not
less than that in
the overlaid
subcell.
Low In the coverage area of the
entire co-cell, the overlaid
subcell covers only morethan half of the area. Because
the underlaid subcell has
more TRXs, which can cover
the remaining area, there is a
low risk enabling the co-
BCCH function.
When the underlaid
subcell is not congested,
the underlaid subcellcarries more traffic to
lower the risk caused by
the handovers from
overlaid subcell to
underlaid subcell in busy
hours.
Setting the value of the
UtoO HO Received
Level Threshold to
adjust the traffic of the
overlaid and underlaid
subcells. The smaller thevalue is, the more the
handovers number is.
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No.
ScenarioDescription
Risk Scenario Analysis Solution
3 l The distance
between sites is
from 800 meters
to 1,600 meters.
l The number of
TRXs in the
underlaid
subcell is less
than that in the
overlaid subcell.
Medi
um
In the coverage area of the
entire co-cell, the overlaid
subcell covers only more
than half of the area. Because
the underlaid subcell has
fewer TRXs, it may not or
just be able to carry the
traffic in the remaining area.
In busy hours, most of the
traffic is allocated to the
overlaid subcell through
handovers. The following
conditions may occur:
l Some calls outside thecoverage area of the
overlaid subcell are
handed over to the
overlaid subcell and the
handover fails.
l With the increase of the
cell traffic, the underlaid
subcell becomes more
congested and the
overlaid subcell becomes
more idle. In addition, the
counters values, such as
the handover success rage
from the underlaid subcell
to the overlaid subcell and
the DCS1800 channel
occupation rate, are
lowered.
Enable the half-rate
services or increase the
number of TRXs in the
underlaid subcell.
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No.
ScenarioDescription
Risk Scenario Analysis Solution
4 l The distance
between sites is
more than 1,600
meters.
l The number of
TRXs in the
underlaid
subcell is not
less than that in
the overlaid
subcell.
Medi
um
In the coverage area of the
entire co-BCCH cell, the
overlaid subcell covers less
than half of the area. Because
the underlaid subcell has
more TRXs, the following
conditions may occur
according to user numbers
and distributions:
l Most users are in the
overlaid subcell. The
TRXs of the underlaid
subcell can carry the
traffic in the coverage ofthe underlaid subcell. The
underlaid subcell should
carry most of the traffic to
lower the risk cause by the
handover from the
underlaid subcell to the
overlaid subcell in busy
hours.
l When users distribute
properly, the underlaid
subcell may not or just be
able to carry the traffic in
the coverage. The
underlaid subcell
becomes more congested
and the overlaid subcell
becomes more idle. In
addition, the counters
values, such as the
handover success rate
from the underlaid subcell
to the overlaid subcell and
the DCS1800 channeloccupation rate, are
lowered.
None.
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No.
ScenarioDescription
Risk Scenario Analysis Solution
5 l The distance
between sites is
more than 1,600
meters.
l The number of
TRXs in the
underlaid
subcell is less
than that in the
overlaid subcell.
High In the coverage area of the
entire co-cell, the overlaid
subcell covers less than half
of the area. Because the
underlaid subcell has fewer
TRXs, it may not or just be
able to carry the traffic in the
coverage of the underlaid
subcell. The following
problems may occur:
l The underlaid subcell is
congested seriously.
l The overlaid subcell is
idle.
l The handover success rate
from the underlaid subcell
to the overlaid subcell,
and the DCS1800 channel
occupation rate are being
lowered.
Enable the half-rate
services or increase the
number of TRXs in the
underlaid subcell.
The method for determining the risks are as follows:
l In common dual-band network, if the overlaid and underlaid subcells are not congested,
the related performance counters have no change after the co-BCCH cell is enabled.
l In common dual-band network, if the GSM900 subcell is congested earlier than the
DCS1800 cell, forcible load the traffic to the DCS1800 cell will influence the KPI
measurements. If the co-BCCH cell is enabled, the related performance counters are
degraded. For example, the handover success rate from the underlaid subcell to the overlaid
subcell and the DSC1800 channel occupation rate are low.
Risk Analysis of Special Scenarios
You can use the following method to eliminate problems which occur when the co-CC cell is
enabled in special scenarios:
l The TRXs number in the overlaid and underlaid subcells is similar and most of the traffic
should be assigned in the overlaid subcell.
You can lower the value ofUtoO HO Received Level Threshold to increase the traffic
in the overlaid subcell. To avoid ping-pong handovers because of power level fluctuation,
the value ofOtoU HO Received Level Threshold should be less than 25.
l The GSM900 is seriously interfered.
Setting the Concentric Data parameters can avoid such kind problem.
When the distance between sites is less than 1,000 meters, add the traffic in the overlaid
subcell.
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NOTE
When the interference band is high, the quality is bad and the call drop ratio is 1.2 times of that of
the DSC1800, the G is judged to be seriously interfered.
l In common dual-band network, only few sites are configured to be the co-BCCH cells. The
other sites are single-band or dual-band sites.
In common dual-band network, the DCS1800 cell is at the Level 2 and the G cell is at the
level 3. That is, the DCS1800 cell level is higher than the G cell level. In this condition,
the following may occur when the co-BCCH cell is enabled:
If the level of the co-BCCH cell is set to level 2, the traffic absorption capability in the
coverage of the G TRX becomes enhanced. The traffic of the neighboring cells is
absorbed. Thus, the traffic volume of the cell increases sharply and some related
performance counters are influenced.
If the level of the co-BCCH cell is set to level 3, the traffic in the coverage of the G
TRX is absorbed by the neighboring cells. The cell traffic volume is decreased.
You should enable the co-BCCH cell in the surrounding sites to avoid these risks.
21.6.4 Configuring the Co-BCCH Cell
This topic describes how to configure the co-BCCH cell. You should configure co-BCCH
parameters on the BSC6000 Local Maintenance Terminal.
Procedure
Step 1 Add a cell
1. On the Management Tree tab page of the BSC6000 Local Maintenance Terminal, right-
click the target cell, and then choose Add Cell on the shortcut menu. A dialog box is
displayed, as shown in Figure 21-1.
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Figure 21-1 Adding a cell
2. Select the BTS of the cell on the Cell View, and then clickAdd Cell. A dialog box is
displayed, as shown in Figure 21-2.
Figure 21-2 Selecting the frequency band
3. Set the Frequency Band to GSM900&GSM1800 on the dialog box in Figure 21-2. Click
OK. A dialog box is displayed, as shown in Figure 21-3.
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Figure 21-3 Adding a cell successfully
Step 2 Set the cell attributes.
1. Click Next. A dialog box is displayed, as shown in Figure 21-4.
Figure 21-4 Selecting the cell to be configured
2. In the Cells to be set list box, select the target cell. Then clickSet Cell Properties. A dialogbox is displayed, as shown in Figure 21-5.
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Figure 21-5 Configuring the cell attributes
Step 3 Assign the TRXs to the added cell.
1. Select the TRXs in the Available TRXs list box, as shown in Figure 21-5. The selected
TRXs are displayed in the Assigned TRXs list box, as shown in Figure 21-6.
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Figure 21-6 Selecting TRXs
2. As shown in Figure 21-6, clickFreq Config. A dialog box is displayed, as shown in Figure
21-7.
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Figure 21-7 Selecting frequencies
3. Select the GSM900 and DCS1800 frequencies, and then clickOK. A dialog box is
displayed, as shown in Figure 21-6.
Step 4 Configure the attributes of the assigned TRXs.
1. Select the assigned TRX in the Assigned TRXs list box, and then clickTRX Config. A
dialog box is displayed, as shown in Figure 21-8.
Figure 21-8 Assign frequencies
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2. Double-clickAvailable Frequencies on the Available Frequencies to add the frequencies
to the Assigned Frequencies list box.
3. Configure the attributes of the HW_Concentric Attribute on the Device Attributes, as
shown in Figure 21-9.
Figure 21-9 Configuring the attributes of the concentric cell
Step 5 ECSE
1. As shown in Figure 21-5, clickCall Control. A dialog box is displayed, as shown in
Figure 21-10.
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Figure 21-10 Configuring the ECSC
2. Configure the ECSE according to actual cases.
NOTE
If you set the ECSC to No, the MS reports the Classmark 3 queried by the MSC. Before the MSC
queries the Classmark 3, the MS is assigned to the channel where the GSM900 TRX is located firstly.
Thus, the load of the underlaid subcell may be too high.
Step 6 Set the handover parameters.
1. As shown in Figure 21-6, clickHandover Data. A dialog box is displayed, as shown in
Figure 21-11.
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Figure 21-11 Set the Concentric Circles HO Allowed
2. Select Concentric Circles HO Allowed.
3. Click Advanced. A dialog box is displayed, as shown in Figure 21-12.
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Figure 21-12 Configure the advanced attributes of the concentric cell
4. Set the UtoO Traffic HO Allowed to Yes.
NOTE
UtoO Traffic HO Allowed can be set when the Concentric Circles HO Allowed is set toYes. Set
the Concentric Circles HO Allowed to Yes. The serving cell changes to be the neighbor cell
automatically and cannot be deleted. Similar to the signal strength measurement of the neighbor cells,
the signal strength of the BCCH TRX can be measured with the enhanced concentric cell handover
algorithm. Thus, the BCCH TRX signal strength error caused by the common concentric cell
handover algorithm can be avoided.
Step 7 Set other parameters.
1. Set the Pref. Subcell in HO of Intra-BSC and Incoming-to-BSC HO Optimum Layer
to Underlaid Subcell.
2. Set the Assign Optimum Layer, Assign-optimum-level Threshold and TA Threshold
of Assignment Pref..
3. Set the Concentric Circles HO Allowed,UL to OL HO Allowed, OL to UL HO
Allowed and Concentric Circles HO Allowed.
4. Set the TA for UO HO Allowed, RX_LEV for UO HO Allowed, RX_QUAL for UO
HO Allowed andUtoO Traffic HO Allowed.
----End
21.6.5 Deactivating the Co-BCCH Cell
This topic describes how to deactivate the co-BCCH cell. You can deactivate the co-BCCH cell
on the BSC6000 Local Maintenance Terminal.
Prerequisite
If the cell to be adjusted is not the co-BCCH cell, you should delete the cell, and then add the
cell.
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Procedure
Step 1 Delete the original cell.
1. On the Management Tree tab page of the BSC6000 Local Maintenance Terminal, right-
click the target cell, and then choose Delete Cell on the shortcut menu. A dialog box isdisplayed, as shown in Figure 21-13.
Figure 21-13 Deleting the original cell
2. Double-click the target cell in the Cell view list box to add the cell to the Cells to be
deleted list box, as shown in Figure 21-14.
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Figure 21-14 Selecting the cell to be deleted
3. Click Finish to complete the deletion.
Step 2 Add and configure the cell.
----End
21.7 Maintenance Information
This topic describes the maintenance information about the co-BCCH cell. The maintenance
information consists of the performance counters related to the co-BCCH cell.
Alarms
None.
Counters
Table 21-5 lists the performance counters related to the co-BCCH cell.
Table 21-5 Performance counters related to the co-BCCH cell
Counter Description
Mean Uplink Receive Level during
Concentric Cell Handover Initiation (Overlay
to Underlay)
Indicates the mean uplink receive level in the
concentric handover from the overlaid
subcell to the underlaid subcell.
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Counter Description
Mean Downlink Receive Level during
Concentric Cell Handover Initiation (Overlay
to Underlay)
Indicates the mean downlink receive level in
the concentric handover from the overlaid
subcell to the underlaid subcell.
Mean Uplink Receive Level during
Concentric Cell Handover Initiation
(Underlay to Overlay)
Indicates the mean uplink receive level in the
concentric handover from the underlaid
subcell to the overlaid subcell.
Mean Downlink Receive Level during
Concentric Cell Handover Initiation
(Underlay to Overlay)
Indicates the mean downlink receive level in
the concentric handover from the underlaid
subcell to the overlaid subcell.
Mean Timing Advance during Concentric
Cell Handover Initiation (Overlay to
Underlay)
Indicates the mean TA value in the concentric
handover from the overlaid subcell to the
underlaid subcell.
Mean Timing Advance during Concentric
Cell Handover Initiation (Underlay to
Overlay)
Indicates the mean TA value in the concentric
handover from the underlaid subcell to the
overlaid subcell.
Internal Intra-Cell Handover Requests
(Overlay to Underlay)
Indicates the number of requests for the
concentric handover from the underlaid
subcell to the overlaid subcell.
Internal Intra-Cell Handover Requests
(Underlay to Overlay)
Indicates the number of requests for the
concentric handover from the overlaid
subcell to the underlaid subcell.
Internal Intra-Cell Handover Commands(Underlay to Overlay)
Indicates the number of commands of internalintra-cell handover from the underlaid subcell
to the overlaid subcell.
Internal Intra-Cell Handover Commands
(Overlay to Underlay)
Indicates the number of commands of internal
intra-cell handover from the underlaid subcell
to the overlaid subcell.
Failed Internal Intra-Cell Handovers
(Channel Unavailable) (Underlay to Overlay)
Indicates the number of failed internal intra-
cell handovers caused by the unavailable
channel. The handover is from the underlaid
subcell to the overlaid subcell.
Failed Internal Intra-Cell Handovers(Channel Unavailable) (Overlay to Underlay)
Indicates the number of failed internal intra-cell handovers caused by the unavailable
channel. The handover is from the overlaid
subcell to the underlaid subcell.
Failed Internal Intra-Cell Handovers (Other
Causes) (Underlay to Overlay)
Indicates the number of failed internal intra-
cell handovers caused by other reasons except
the unavailable channel. The handover is
from the underlaid subcell to the overlaid
subcell.
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Counter Description
Failed Internal Intra-Cell Handovers (Other
Causes) (Overlay to Underlay)
Indicates the number of failed internal intra-
cell handovers caused by other reasons except
the unavailable channel. The handover is
from the overlaid subcell to the underlaid
subcell.
Success Rate of Internal Intra-Cell Handover
(Underlay to Overlay)
Indicates the success rate in the handover
from the underlaid subcell to the overlaid
subcell.
Success rate of internal intra-cell handover
(underlay to overlay) = [(Successful internal
intra-cell handovers + Successful incoming
internal inter-cell handovers) / (Internal intra-
cell handover requests + Incoming internal
inter-cell handovers)] x 100%
Success Rate of Internal Intra-Cell Handover
(Overlay to Underlay)
Indicates the success rate in the handover
from the overlaid subcell to the underlaid
subcell.
Success rate of internal intra-cell handover
(overlay to underlay) = [Successful internal
intra-cell handovers (overlay to underlay) /
Internal intra-cell handover requests (overlay
to underlay)] x 100%
MRs on TCHs (TCHF) (M900/850 Cell) Indicates the number of MRs received on the
signaling channel of the TRX of the underlaidsubcell
MRs on TCHs (TCHF) (M1800/1900 Cell) Indicates the number of MRs received on the
signaling channel of the TRX of the overlaid
subcell
MRs on TCHs (TCHH) (M900/850 Cell) Indicates the number of MRs received on the
traffic channel in the TRX of the underlaid
subcell
MRs on TCHs (TCHH) (M1800/1900 Cell) Indicates the number of MRs received on the
traffic channel in the TRX of the overlaid
subcell
MRs on Signaling Channels (Underlaid
Subcell)
Indicates the traffic volume on the traffic
channel in the TRX of the underlaid subcell
MRs on Signaling Channels (Overlaid
Subcell)
Indicates the traffic volume on the traffic
channel in the TRX of the overlaid subcell
Channel Assignment Requests (Underlaid
Subcell Only)
Indicates the number of the channel
assignment in all the procedures.
Channel Assignment Requests (Overlaid
Subcell Only)
Indicates the number of channel assignment
request for the overlaid subcell in all the
procedures.
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Counter Description
Channel Assignment Requests (Underlaid
Subcell Preferred)
Indicates the number of requests for assigning
channels to the underlaid subcell based on the
preferred algorithm in all the procedures.
Channel Assignment Requests (Overlaid
Subcell Preferred)
Indicates the number of requests for assigning
channels to the overlaid subcell based on the
preferred algorithm in all the procedures.
TCH Assignment Requests (Underlaid
Subcell Preferred)
Indicates the number of requests for assigning
channels to the underlaid subcell based on the
preferred algorithm in all the procedures.
TCH Assignment Requests (Overlaid Subcell
Preferred)
Indicates the number of requests for assigning
channels to the overlaid subcell based on the
preferred algorithm in all the assignment
procedures.
Channel Assignment Requests in Incoming
Internal Inter-Cell Handover Procedure
(TCH)(Underlaid Subcell Preferred)
Indicates the number of requests for assigning
channels to the underlaid subcell based on the
preferred algorithm in the incoming internal
inter-cell handover procedure.
Channel Assignment Requests in Incoming
Internal Inter-Cell Handover Procedure
(TCH) (Overlaid Subcell Preferred)
Indicates the number of requests for assigning
channels to the overlaid subcell based on the
preferred algorithm in the incoming internal
inter-cell handover procedure.
Channel Assignment Requests in Incoming
External Inter-Cell Handover Procedure(TCH) (Underlaid Subcell Preferred)
Indicates the number of requests for assigning
channels to the underlaid subcell based on thepreferred algorithm in the incoming external
inter-cell handover procedure.
Channel Assignment Requests in Incoming
External Inter-Cell Handover Procedure
(TCH) (Overlaid Subcell Preferred)
Indicates the number of requests for assigning
channels to the ovderlaid subcell based on the
preferred algorithm in the incoming external
inter-cell handover procedure.
Channel Assignment Overflows (TCH)
(Underlaid Subcell Preferred)
Indicates the number of overflows in the
channel assignment when the system selects
the TCH of the underlaid subcell preferred.
Channel Assignment Overflows (TCH)
(Overlaid Subcell Preferred)
Indicates the number of overflows in the
assignment when the system selects the TCH
of the overlaid subcell preferred.
Channel Assignment Overflows in Incoming
Internal Inter-Cell Handover Procedure
(TCH) (Underlaid Subcell Preferred)
Indicates the number of overflows in the
incoming internal inter-cell handover
procedure when the system selects the TCH
of the underlaid subcell preferred.
Channel Assignment Overflows in Incoming
Internal Inter-Cell Handover Procedure
(TCH) (Overlaid Subcell Preferred)
Indicates the number of overflows in the
incoming internal inter-cell handover
procedure when the system selects the TCH
of the overlaid subcell preferred.
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Counter Description
Channel Assignment Overflows in Incoming
External Inter-Cell Handover Procedure
(TCH) (Underlaid Subcell Preferred)
Indicates the number of overflows in the
incoming external inter-cell handover
procedure when the system selects the TCH
of the underlaid subcell preferred.
Channel Assignment Overflows in Incoming
External Inter-Cell Handover Procedure
(TCH) (Overlaid Subcell Preferred)
Indicates the number of overflows in the
incoming external inter-cell handover
procedure when the system selects the TCH
of the overlaid subcell preferred.
Channel Assignment Overflows in Underlaid
Subcell (TCH)
Indicates the number of overflows in the TCH
assignment of the underlaid subcell.
Channel Assignment Overflows in Overlaid
Subcell (TCH)
Indicates the number of overflows in the TCH
assignment of the overlaid subcell.
Channel Assignment Overflows in Underlaid
Subcell (SDCCH)
Indicates the number of overflows in the
SDCCH assignment of the underlaid subcell.
Channel Assignment Overflows in Overlaid
Subcell (SDCCH)
Indicates the number of overflows in the
SDCCH assignment of the overlaid subcell.
Channel Assignment Overflows in Underlaid
Subcell (TCHF)
Indicates the number of overflows in the
TCHF assignment of the underlaid subcell.
Channel Assignment Overflows in Overlaid
Subcell (TCHF)
Indicates the number of overflows in the
TCHF assignment of the overlaid subcell.
Channel Assignment Overflows in Underlaid
Subcell (TCHH)
Indicates the number of overflows in the
TCHH assignment of the underlaid subcell.
Channel Assignment Overflows in Overlaid
Subcell (TCHH)
Indicates the number of overflows in the
TCHH assignment of the overlaid subcell.
Failed Handovers from Underlaid Subcell to
Overlaid Subcell due to Busy Channels in
Overlaid Subcell
Indicates the number of failed handovers
from the underlaid subcell to the overlaid
subcell as all the channels of the overlaid
subcell are busy.
Failed Handovers from Overlaid Subcell to
Underlaid Subcell due to Busy Channels in
Underlaid Subcell
Indicates the number of failed handovers
from the overlaid subcell to the underlaid
subcell as all the channels of the overlaidsubcell are busy.
21.8 References
This topic describes the references of the co-BCCH cell. The references refer to the co-BCCH
description documents written by related standard- making organizations. For details about the
features of the co-BCCH, refer to the following documents:
l GSM 08.08 : "Mobile Switching Centre - Base Station system (MSC-BSS) Interface Layer
3 Specification"
l GSM 04.08 : "Mobile Radio Interface - Layer 3 Specification"
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