Training VAMOS HUAWEI

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GBSS13.0 BSC6900 (V900R013C00) VAMOS Feature Description

Global Technical Support

Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page2

Objectives

Upon completion of this course, you will be able to:

Know the basic principles of voice service over adaptive multi-user

channels on one slot (VAMOS).

Known the design and implementation method of VAMOS.


Contents

VAMOS Feature Description

1. Basic Principles of VAMOS

2. Application Scenarios

3. Design and Implementation Method

4. Data Configuration Procedure

5. Description of Performance Measurement

6. Acronyms and Abbreviations


Basic Principles of VAMOS

VAMOS is used to increase the capacity of the global system for mobile

communications (GSM) network. VAMOS multiplexes two users on one

full-rate or half-rate channel to increase the number of available radio

channels on the Um interface.

Function description

Left-right separation: distinguishing users based on time.Up-down separation: distinguishing users based on the TSC.


Basic Principles of VAMOS The base transceiver station (BTS) uses the AQPSK modulation mode and orthogonal TSC in the

downlink. Therefore, the mobile station (MS) must support SAIC to correctly demodulate downlink signals.

In the uplink, the MS still uses the GMSK modulation mode to modulate signals. The BTS demodulates

two signals by using the interference cancellation algorithm (such as IRC and SIC) and orthogonal TSC.

GMS

GMS

TS 0

TS 1

TS 2

Uplin

GMSK

GMSK

TS 0

TS 1

TS 2

Uplink

TS 0 TS 1 TS 2

Downlink

TSC 1

TSC 2

TS 0 TS 1 TS 2

α-QPSK

Downlink

TSC 1


Basic Principles of VAMOS Downlink signal modulation

Downlink signal demodulation (SAIC algorithm)

The BTS uses the modulation mode similar to QPSK to send signals. The data of two users is mapped to different bits of the QPSK symbol. Then, π/2 phase rotation is performed for the symbol. The existing SAIC MS can directly demodulate signals from those received on the corresponding subchannel.

The SAIC receiver separates the received signals as real and imaginary parts and takes them as signal diversity tributaries so that the diversity effect is obtained by using one antenna.


Basic Principles of VAMOS Uplink signal modulation: The MS uses the existing modulation algorithm to modulate signals.

Downlink signal demodulation (SAIC algorithm)

Successive interference cancellation (SIC) uses the interference rejection combing (IRC) algorithm to demodulate the strong-power user channels, deducts the strong-power user information from the received signals, and then uses IRC to demodulate the remaining weak-power signals.


Basic Principles of VAMOS TSC users implement channel estimation, that is, obtain the channel

characteristics. Based on the modulation and demodulation modes, third

generation partnership project (3GPP) defines eight training sequences

numbered 0 to 7. For example, training sequence defined by normal burst

in GMSK modulation mode:

The eight TSCs defined by 3GPP are not closely related. To obtain better

orthogonality, The VAMOS workgroup defines a new TSC for VAMOS

multiplexing.


Basic Principles of VAMOS To support VAMOS better, 3GPP introduces a new TSC and an

advanced receiver structure. MSs are classified as follows based on

whether they support the functions:MS

ClassificationMS Capability Pairing

RestrictionSAIC New

Training Sequence

VAMOS Performance Description

Marketing

Legacy Non-SAIC Considering the alpha QPSK technology, a non-SAIC MS may be multiplexed on the VAMOS subchannel in the case of certain power offset.

A legacy non-SAIC MS cannot be paired with a legacy non-SAIC MS or legacy SAIC MS.

Not supported

Not supported

Low performance

The current MS penetration rate is 70% (3GPP).

Legacy SAIC Compared with a non-SAIC MS, a legacy SAIC MS features more powerful demodulation capability but supports only the existing TSC. It supports VAMOS multiplexing well and does not require much for the MS on another subchannel.

A legacy SAIC MS cannot be paired with a legacy non-SAIC MS (the pairing is theoretically feasible, but it requires much for power offset; therefore, it is not applicable).

Supported Not supported

Crucial for the existing MS to support VAMOS. Its capacity gain is much lower than the VAMOS MS.

The current MS penetration rate is 30% (3GPP).

VAMOS level I It supports the new TSC defined for VAMOS.

None. Supported Supported It supports high-performance VAMOS truly.

It is not launched to the market yet.

VAMOS level II It supports a more advanced demodulation algorithm, supports the new TSC, and can further improve the demodulation performance based on the TSC used by the two multiplexed channels.

None. Supported Supported Further enhanced.

It is not launched to the market yet.


Application Scenarios VAMOS is applicable to the scenario

where network frequencies are loosely multiplexed and the capacity is limited. Typical scenarios are as follows:

Wide coverage in rural areas

Thin network after GSM refarming

Other scenarios

Rural area

Refarmed GSM

The GSM network will coexist with the 3G or even 4G network in a long term. On the one hand, the number of GSM users decreases gradually, and the GSM network undergoes continuous refarming; on the other hand, the operator needs to maintain a thin GSM network for a long time to guarantee the coverage for users. On the basis of the AHS application, VAMOS can further meet the traffic peak requirements on the thin GSM network. That is, a larger traffic capacity can be provided with a small configuration.

In the scenario of wide coverage in rural areas, the frequency multiplexing rate is low. On the basis of the AHS application, if the penetration rate of VAMOS MSs is high, satisfactory voice capacity gain can be obtained.

For some areas where the number of GSM users rapidly increases, when the user capacity requirement becomes higher, the operator can increase TRXs and improve frequency multiplexing rate to expand the capacity. This may greatly decrease the VAMOS gain. Therefore, the VAMOS technology is not applicable to the area where the number of GSM users still increases rapidly.


Impacts of VAMOS on the Network (1) After VAMOS is enabled, the number of available air

interface channels increases. As a result, the number of transmission timeslots of the Abis, Ater, and A interfaces increases. Therefore, before VAMOS is enabled, transmission resources must be increased.

With the increase of transmission resources, the Abis/Ater/A interface resources must also be increased, that is, transmission interface boards in the BSC must be increased.

Along with the increase of A interface resource, TC boards must also be increased.


Impacts of VAMOS on the Network (2) The orthogonal TSC is required to enable VAMOS. Therefore,

the TSCs on the network must be re-planed.

VAMOS is not used: The TSCs and BCCs are bound on the

network, and the TSCs can be planned at will.

VAMOS is used: To prevent cells from using the same frequency

and TSC in the case of inter-cell timeslot alignment, re-plan the

TSCs on the network by using a method similar to frequency

planning before enabling VAMOS. This method is meant to enlarge

the multiplexing distance between the cells that use the same TSC.

After VAMOS is used, the cells need to use the second TSC, and

therefore the second TSC must be planed so that the cells do not

use the same TSC as peripheral cells.


Impacts of VAMOS on the Network (3)

After VAMOS is enabled, more BTS destination signaling

point (DSP) processing resources are required (the number

of channels to be processed concurrently increases and

new modulation algorithms need to be used), and the

service processing capability of the BTS deteriorates. In

busy hours, the EDGE rate and EDGE+ rate are decreased.


Design and Implementation Method

After VAMOS is enabled for a cell, half-rate channels can implement VAMOS multiplexing. This can be explained as follows: one subchannel in a timeslot is equivalent to four HR subchannels instead of two HR subchannels. One full-rate channel is still indicated as one channel.

VAMOS channel management

VAMOS supports full-rate and half-rate channels but it supports only half-rate channels in GBSS13.0.



In normal cases, when user A and user B access the network independently, each

occupies one half-rate channel. If user A and user B meet the multiplexing conditions,

the BSC hands user B over to the channel occupied by user A.

If user B is accessing the network and meets the multiplexing conditions, the BSC

directly assigns user B to the channel occupied by user A.

VAMOS channel multiplexing



The BSC hands user B over to another half-rate channel.

VAMOS channel demultiplexing can be performed based on load or quality.

VAMOS channel demultiplexing



VAMOS transmission resource management

VAMOS supports TDM, IP, and high-level data link control

(HDLC) transmission resources.

VAMOS supports TDM: If an office adopts TDM, the office

must be configured with FlexAbis. Expand channel numbers

to support VAMOS multiplexing.

VAMOS supports IP: After VAMOS is used, subchannel

numbers are expanded to 0 to 3.

VAMOS supports HDLC: After VAMOS is used, subchannel

numbers are expanded to 0 to 3.



VAMOS processing capability adaptation

For the MRFU/MRRU V1&V2, service restrictions coexist

with VAMOS, EDGE, and EDGE+. Based on the DSP

computing capability of the supported carrier group, the

BSC determines the VAMOS channel of the timeslot in the

carrier group.

After VAMOS is used, the DSP decreases the uplink rate of

EDGE and EDGE+ services based on GMSK modulation if

the DSP processing capability is low.


Design and Implementation MethodMS compatibility Due to MS compatibility, MS type database is not available

on the BSC. This database records the VAMOS capability of MSs of different types. The MSs are classified as follows:

MSs in the white list: This type of MSs can completely support VAMOS multiplexing.

MSs in the gray list: The performance of this type of MSs varies with the TSC combination. The hop-Alpha QPSK modulation mode, however, can be used to upgrade the MS performance.

If MS compatibility is not considered, the BSC implements multiplexing based on the VAMOS support capability reported by the MS by using the classmark. If MS compatibility is considered, the BSC obtains the MS type and then implements multiplexing based on the MS compatibility stored in the MS type database.


Design and Implementation MethodMS compatibility

You can run ADD GMSSAICCAP to set the MS type

database on the BSC, that is, add MSs in the white list and

gray list manually.

You can configure up to 20,000 records in the white list and

gray list in total.



Mute-SAIC MS identification

Mute-SAIC MS: An MS that supports SAIC but does not report the SAIC support capability. This type of MSs affects the VAMOS multiplexing rate.

If the CONNECTACK message is received during a call and the channel quality of the call meets the condition, a detection request is initiated to instruct the BTS to implement automatic mute-SAIC identification.

After the BTS receives the automatic mute-SAIC identification request, the BTS starts automatic mute-SAIC identification.


Design and Implementation MethodMute-SAIC MS identification

Procedure for identifying Mute-SAIC MSs by the BTS:

The BSC records the MS type (TAC in the IMEI) based on the BTS test result and periodically exports the records to the OMU.

The BTS forcibly changes the modulation mode of downlink data to alpha-QPSK,

and sends dummy frames on another channel.

The BTS determines whether the MS supports VAMOS based on the downlink qu

ality changes.

IMEI 15 digits

TAC

8 digits

SNR

6 digits

CD/SD

1 digit


Design and Implementation MethodMute-SAIC MS identification You can run EXP MSSAICCAPMML to convert the BSC detection

result into a man-machine language (MML) script and save it in \bam\version_x\ftp \ms_saic_cap on the OMU. Here, x refers to the specific version number.

You can use the file manager on the Web LMT to export the generated MML script to a local path. Then, run the MML script to import the automatic detection result into the MS database.

Mute-SAIC MS identification causes network key performance indicators

(KPIs) to degrade.



Automatic problem MS identification

Problem MS: An MS that supports SAIC and causes

call drops during multiplexing. This type of MSs

requires to be identified.

The procedure for identifying a problem MS is the

same as that for identifying a mute-SAIC MS.

Automatic problem MS identification causes KPIs to degrade.



Operation and maintenance of VAMOS

Run SET FHO to force calls to implement VAMOS

multiplexing.

VAMOS is mutually exclusive with the following functions:

IBCA and Flex-MAIO

Flex-TSC

EMR

Concentric circle

Hybrid cell

Intra-cell asynchronous handover (including the repeater and frame offset)

External DXX connection in TDM transmission


Data Configuration Procedure VAMOS configuration procedure

Step 1: If the BTS transmission mode is TDM, when you run

ADD BTS to add a BTS, set Flex Abis Mode to FLEX_ABIS.

For an existing BTS, you can run MOD BTS to set Flex Abis

Mode to FLEX_ABIS. If the BTS transmission mode is IP or

HDLC, skip this step.


Data Configuration Procedure

VAMOS configuration procedure

Step 2: Run SET GCELLPWRBASIC to set Power Control

Switch to PWR3.




Step 3: Run SET GCELLPWR3 to set III Power Control to

YES.




Step 4: Run SET GCELLVAMOS to set VAMOS to ON.


Data Configuration Procedure VAMOS configuration procedure

Step 5: Run SET GCELLVAMOSPWR to set Allow alpha-

QPSK Power Control and Allow SIC Power Control to ON.


Data Configuration Procedure Configuration procedure for mute-SAIC MS identification (optional)

Step 6: Run SET GCELLVAMOS to set Mute SAIC Terminal

Processing Switch and Auto Mute SAIC Identification Switch to

ON.


Data Configuration Procedure Configuration procedure for problem MS identification

(optional) Step 7: Run SET GCELLVAMOS to set Problem SAIC

Terminal Processing Switch and Problem SAIC Terminal Identify Switch to ON.


Configuration Procedure on the CME

VAMOS Configuration Procedure

Step 1: If the BTS service mode is set to TDM, set Flex Abis Mode to Flex Abis when

adding BTSs with the wizard, and run the MOD BTS command to set Flex Abis Mode to

Flex Abis. If the BTS service mode is set to IP or HDLC, ignore this step.




Step 1: If the BTS already exists, right-click the BTS, and choose Modify Multiplexing

Mode or Flex Abis Mode… from the shortcut menu, and set Flex Abis mode to Flex

Abis in the displayed dialog box. If the service mode of the BTS is set to IP or HDLC,

ignore this step.




Step 2: Set Power Control Switch to Power controlIII in the Basic Parameters for

Power Control of Cell table.

The procedure for navigating to the Basic Parameters for Power Control of Cell table is as follows: On

the Main View tab, right-click a cell, and choose Cell Configuration Express from the shortcut menu.

On the Properties tab, click Basic Parameters for Power Control of Cell. The Basic Parameters for

Power Control of Cell table is displayed in the right pane.




Step 3: Set III Power Control Optimized Enable to Yes in the Parameters for Power

Control III of Cell table.

The procedure for navigating to the Parameters for Power Control III of Cell table is as follows: On the

Main View tab, right-click a cell, and choose Cell Configuration Express from the shortcut menu. On

the Properties tab, click Parameters for Power Control III of Cell. The Parameters for Power Control

III of Cell table is displayed in the right pane.




Step 4: Set VAMOS Switch to On in the VAMOS Channel Multiplex Parameters of Cell

table.

The procedure for navigating to the VAMOS Channel Multiplex Parameters of Cell table is as follows:

On the Main View tab, right-click a cell, and choose Cell Configuration Express from the shortcut

menu. On the Properties tab, click VAMOS Channel Multiplex Parameters of Cell. The VAMOS

Channel Multiplex Parameters of Cell table is displayed in the right pane.




Step 5: Set Allow alpha QPSK Power Control to On and Allow SIC Power Control to

On in the Power Control Parameters for VAMOS Call of Cell table.

The procedure for navigating to the Power Control Parameters for VAMOS Call of Cell table is as

follows: On the Main View tab, right-click a cell, and choose Cell Configuration Express from the

shortcut menu. On the Properties tab, click Power Control Parameters for VAMOS Call of Cell. The

Power Control Parameters for VAMOS Call of Cell table is displayed in the right pane.



Setting Mute SAIC Identification (Optional)

Step 6: Set Mute SAIC Terminal Processing Switch to On and Auto Mute SAIC

Identification Switch to On in the VAMOS Channel Multiplex Parameters of Cell table.







Setting Faulty Terminal Detection (Optional)

Step 7: Set Problem SAIC Terminal Identify Switch to On and Problem SAIC TRMNL

Identify Manual Start to On in the VAMOS Channel Multiplex Parameters of Cell

table.






Verification Procedure VAMOS verification procedure

Step 1: Assume that VAMOS is enabled for a cell and two MSs

supporting VAMOS are used in the cell to initiate calls,

configure parameters so that the two calls occupy half-rate

channels.

Step 2: Run SET FHO to forcibly multiplex one half-rate call on

the other channel.


Description of Key Parameters (1)Parameter Name Parameter Description Impact on the Network

VAMOS Switch Specifies whether to enable VAMOS on the network.

VAMOS sacrifices quality to increase capacity. Therefore, if VAMOS is enabled in a cell, the network capacity increases and the congestion rate decreases, but the network-quality KPIs are affected to a certain extent.

Primary TSC in VAMOS Specifies the primary TSC used on the network when VAMOS is enabled in a cell. Before any call enters the VAMOS mode, the primary TSC is allocated preferentially. After VAMOS pairing succeeds, the primary and secondary TSCs are determined based on the TSC that is used by the first call connected to the timeslot.

TSC selection affects MSs.

Secondary TSC in VAMOS

Specifies the secondary TSC used on the network when VAMOS is enabled in a cell. Before any call enters the VAMOS mode, the primary TSC is allocated preferentially. After VAMOS pairing succeeds, the primary and secondary TSCs are determined based on the TSC that is used by the first call connected to the timeslot.

TSC selection affects MSs.


Description of Key Parameters (2)Parameter Name Parameter Description Impact on the Network

Allow alpha-QPSK Power Control

Specifies whether to enable the alpha-QPSK power control sub-algorithm of the VAMOS technology (one timeslot multiplexed by voice services of multiple users).

If the alpha-QPSK downlink power control algorithm is enabled, the BTS power consumption decreases, the network interference decreases, and the downlink network drive test (DT) quality is improved.

Allow SIC Power Control Specifies whether to enable the uplink SIC power control sub-algorithm of the VAMOS technology.

If the SIC uplink power control algorithm is enabled, the MS power consumption decreases, the network interference decreases, and the uplink network DT quality is improved.

Mute SAIC Terminal Processing Switch

Specifies whether to enable the mute-SAIC MS processing function of a cell. ON: enable the mute-SAIC MS processing function; Off: disable the mute-SAIC MS processing function. Mute-SAIC MS processing includes mute-SAIC matching and identification based on the database and automatic mute-SAIC identification.

If this switch is on, IMEI identification is performed for a call before TCH assignment. As a result, call connection is delayed.

Auto Mute SAIC Identification Switch

Specifies whether to enable the automatic mute-SAIC identification function of a cell. Mute-SAIC MS: An MS that supports SAIC but is reported as incapable of SAIC. ON: enable the automatic mute-SAIC identification function of a cell; Off: disable the automatic mute-SAIC identification function of a cell.

If this switch is on, uplink and downlink DTX must be disabled during mute-SAIC identification, and this influences the network interference. Alpha-QPSK modulation is used in the downlink, and the downlink receiving quality is degraded in a call.


Description of Performance Measurement CountersCounter Name Short Name Counter Description Remarks

Number of Successful VAMOS Candidate Call Decisions (Assignment)

A3100J This counter measures the total number of new calls that meet the VAMOS candidate user conditions during assigned channel multiplexing determination. If the value of this counter is low, it indicates that the SD channel quality is low or the number of new calls that meet the VAMOS candidate user conditions is small because the VAMOS candidate user conditions set for new calls are strict (excessively higher requirements for quality and ATCB).

Number of VAMOS Channel Multiplexing Attempts (Assignment)

A3100L

This counter measures the total number of times that a new call during assignment and an established call can be paired (the paring is determined in assignment mode) in a cell. It is used to calculate the assigned channel multiplexing success rate and the ratio of the number of assigned channel multiplexing attempts to the total number of channel multiplexing attempts. If the value of this counter is far smaller than the value of Number of Successful VAMOS Candidate Call Decisions (Assignment), you can loosen the path loss offset threshold and VAMOS overload threshold involved in assigned channel multiplexing determination to allow more users to be paired.

Number of VAMOS Channel Multiplexing Commands (Assignment)

A3100M

This counter measures the total number of VAMOS channel assignment commands for VAMOS channel multiplexing (VAMOS channel multiplexing is triggered by assignment) in a cell. If the value of this counter is far smaller than the value of Number of VAMOS Channel Multiplexing Attempts (Assignment), it indicates that lower-layer connection fails or the Abis interface resources are insufficient.


Description of Traffic Measurement Counters

Counter Name Short Name Counter Description Remarks

Number of Failed VAMOS Channel Multiplexing Attempts (Assignment)

A3100N

This counter measures the number of times that access to the specified VAMOS channel fails after the VAMOS channel assignment command is delivered after VAMOS channel multiplexing is triggered by assignment in a cell. This counter reflects the air interface quality during user access. If the value of this counter is large, it indicates that the VAMOS candidate user selected for pairing is improper. You can set strict multiplexing candidate user determination conditions for new calls to guarantee the performance during VAMOS channel access by users.

Number of Successful VAMOS Candidate Call Decisions (Intra-Cell Handover)

H3050

This counter measures the total number of established calls that meet the VAMOS candidate user conditions. If the value of this counter is low, it indicates that the quality of the channel for non-VAMOS calls is low or the VAMOS candidate user conditions set for established calls are strict (excessively higher requirements for quality and ATCB). You can adjust the power control parameters or loosen the VAMOS candidate user conditions for new calls to allow more established VAMOS candidate users.

Number of VAMOS Channel Multiplexing Attempts (Intra-Cell Handover)

H3051

This counter measures the total number of times that two established calls can be paired (the pairing is determined in intra-cell handover mode) in a cell. It is used to calculate the success rate of VAMOS channel multiplexing handovers. If the value of this counter is small, it indicates that the number of non-VAMOS that can be paired on the network is small. You can adjust the power control parameters for common calls to improve the common call quality or loosen the VAMOS multiplexing determination conditions for established calls to increase the number of VAMOS candidate users on the network; in addition, you can loosen the path loss threshold during intra-cell channel multiplexing determination to allow more users to be paired.


Description of Traffic Measurement CountersCounter Name Short Name Counter Description Remarks

Number of VAMOS Channel Multiplexing Commands (Intra-Cell Handover)

H3052

This counter measures the number of handover commands of all the calls that are handed over due to VAMOS channel multiplexing triggered by intra-cell handover in a cell. If the value of this counter is far smaller than the value of Number of VAMOS Channel Multiplexing Commands (Intra-Cell Handover), it indicates that lower-layer connection fails or the Abis interface resources are insufficient.

Number of VAMOS Channel Multiplexing Commands (Intra-Cell Handover)

H3053

This counter measures the number of times that access the specified VAMOS channel fails after the handover commands are delivered (the commands correspond to all the calls that are handed over due to VAMOS channel multiplexing triggered by intra-cell handover) in a cell. This counter reflects the air interface quality during user access. If the value of this counter is large, it indicates that the VAMOS candidate user selected for pairing is improper. You can set strict multiplexing candidate user determination conditions for new calls to guarantee the performance during user handover.

Number of VAMOS Call Handover Attempts (Others)

H3054

This counter measures the total number of handovers that trigger VAMOS channel demultiplexing in a cell. If the value of this counter is large, it indicates that VAMOS demultiplexing is triggered frequently because the VAMOS call power control parameters are improper or the demultiplexing conditions are strict (high load threshold, low quality threshold, and high ATCB threshold).


Description of Traffic Measurement CountersCounter Name Short Name Counter Description Remarks

Number of VAMOS Call Handover Attempts (Others)

H3058

This counter measures the total number of handovers initiated for VAMOS calls due to other reasons in a cell. All the handovers except for VAMOS demultiplexing handovers are included. If the value of this counter is large, modify the handover (of other types) determination parameters to decrease handovers of other types.

Number of VAMOS Call Handover Commands (Others)

H3059

This counter measures the number of handover commands of all the VAMOS calls that are handed over due to other reasons in a cell. All the handovers except for VAMOS demultiplexing handovers are included. If the value of this counter is far smaller than the value of Number of VAMOS Call Handover Attempts (Others), it indicates that congestion occurs, lower-layer connection fails, or Abis transmission resource allocation fails.

Number of Failed VAMOS Call Handover Attempts (Others)

H3060

This counter measures the number of failed handovers after handover commands are delivered (the handover commands correspond to all the VAMOS calls that are handed over due to other reasons) in a cell. This counter reflects the air interface quality during user access. If the value of this counter is large, it indicates that the channel allocated to the selected demultiplexing user is improper. Optimize the channel allocation parameters.


Description of Traffic Measurement Counters

Counter Name Short Name Counter Description Remarks

Number of VAMOS Call Drops (Demultiplexing Handover)

H3061

This counter measures the number of VAMOS call drops caused by handovers that are triggered by VAMOS demultiplexing in a cell. If the value of this counter is large, it indicates that the quality of the channel newly allocated to the user is low or calls are dropped before handovers because VAMOS demultiplexing is not performed in time. If VAMOS demultiplexing is not performed in time, you can adjust the demultiplexing parameters so that demultiplexing is triggered earlier.

Number of VAMOS Call Drops (Other Handover)

H3062

This counter measures the number of VAMOS call drops caused by the handovers except for the handovers that are triggered by VAMOS demultiplexing in a cell. If the value of this counter is large, it indicates that the quality of the channel newly allocated to the user is low or calls are dropped before handovers because handover is not performed in time due to other reasons. If handover is not performed in time due to other reasons, you can adjust the handover algorithm parameters so that handover is triggered earlier.

Number of VAMOS Call Drops (Stable State)

H3063

This counter measures the number of VAMOS call drops in the stable state in a cell. If the value of this counter is large, it indicates that the call quality is low after the user enters the VAMOS stable state. You can adjust the VAMOS power control parameters to improve VAMOS call quality and prevent call drops.


Acronyms and AbbreviationsAcronym or Abbreviation Full Spelling

VAMOS Voice Service over Adaptive Multi-user channels on One Slot

GERAN GSM/EDGE Radio Access Network

MUROS Multi-User Reusing-One-Slot

SAIC Single Antenna Interference Cancellation

SIC Successive Interference Cancellation

IRC Interference Rejection Combing

OSC Orthogonal Sub Channel

CS Circuit Switch


Acronyms and AbbreviationsAcronym or Abbreviation Full Spelling

TSC Training Sequence Code

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