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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:

    HUAWEI BSC6000 Base Station Subsystem

    BSS Feature Description 21 Co-BCCH Cell

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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.

    21 Co-BCCH 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

    HUAWEI BSC6000 Base Station Subsystem

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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,

    21 Co-BCCH Cell

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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.

    HUAWEI BSC6000 Base Station Subsystem

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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.

    21 Co-BCCH Cell

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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.

    HUAWEI BSC6000 Base Station Subsystem

    BSS Feature Description 21 Co-BCCH Cell

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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.

    21 Co-BCCH Cell

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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.

    HUAWEI BSC6000 Base Station Subsystem

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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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