Huawei VAMOS Trial Test

8/10/2019 Huawei VAMOS Trial Test

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VAMOS Trial Test Live Network

Voice servicesover Adaptive Multi-user channels on

OneSlot (VAMOS)


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Scope and Objectives

What is VAMOS?

When and Why to use ?

How VAMOS Work? VAMOS limiting factors

Huawei VAMOS Requirement

KPI Result

Conclusion


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What is VAMOS

VAMOS is Voice Efficiency for GSM which with this technology you canhave up to 4 calls per TS.

As VAMOS does not require new voice channels to be defined, it is anextension of the currently defined full and half rate channels.


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Why and when to deploy

There are numbers of reasons to use VAMOS feature:-

Voice traffic growth .

Network with less frequency bandwidth.

Expand EDGE mobile broadband service .

3G/LTE Introducing

Spectrum re-farming


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VAMOS work principle

Transmitting-simultaneously sending 2 calls.

- TRX: New modulation with double bit rate Adaptive QPSK

- MS: Still using GMSK one call per MS.

Receiving - separating 2 calls from each other .-TSC: Separating the two calls transmitted on the same timeslot .

-MS :SAIC filter out its call using TSC.

-TRX:SIC(IRC) filter out its call use the TSC.

VAMOS requires a pair of training sequences to be allocated to users in a VAMOS pair. Thesetraining sequences are the key when separating the paired users from each other. While thestandardized VAMOS solution supports new training sequences optimized for new VAMOSmobiles, VAMOS can be used in networks with a significant penetration of SAIC mobiles, using thealready defined set of legacy training sequences


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VAMOS work principle

For the Mobiles side there are several functional level.

> SAIC which already available in Market

> VAMOS I &II Near Future (3GPP Rel 9 Q1 2010 but commercial available 2103 and 2014 )

Due to VAMOS Power control less power required so that withlegacy mobile can be paired in way extra power for legacymobile granted due to low VAMOS mobile penetration


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3GPP vs Huawei Network Capacity Gain Expectation

From 3GPP capacity gain simulation in early stages when the Mobiles support SAIC with 50% atleast can have almost 40% gain but from Huawei trial experience with the same penetration thegain are from 10 to 22%


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Limiting Factors

Coverage

Two MS sharing one TS

- 3dB less power for each MS

AQPSK Modulation

- Similar to EDGE peak to average ratio 3 dB reduced power


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Limiting Factors

VAMOS Efficiency

From the above chart show that when ever the interference sourcesbecome higher the MS SAIC(VAMOS) efficiency become less


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Huawei VAMOS Impact on equipment resources

1- The VAMOS feature is supported by the following radio frequency (RF) modules: GRFU V1, GRFU V2, GRFU V2a,RRU3008 V1, RRU3008 V2, RRU3928, RRU3929.

2- Maximum TRXs configured per cell are 4TRX VAMOS support.

3- Power Control

VAMOS power control must be enabled together with the optimized Huawei power control and power control III.

4- Transmission resources

After VAMOS is enabled, more transmission resources of the Abis, Ater, and A interfaces are required.

Take E1 transmission as an example. If the existing E1 resources become insufficient after VAMOS is

enabled, extra E1 resources are required on the Abis, Ater, and A interfaces.

5- Interface board resources

After transmission resources are added, additional Abis, Ater, and A interface boards are required if

the current interface boards are incapable of processing all the transmission resources.

6- Voice processing resources

After VAMOS is enabled, the network capacity for processing voice services increases. Additional

speech service processing boards are required if the current speech service processing boards are

incapable of processing all the voice services.


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VAMOS KPI result

Impacts on KPIsVAMOS can expand network capacity and decrease congestion rate. However, it has adverseimpactson network KPIs, especially speech quality, including receive quality, call drop rate, and meanopinion score (MOS). Therefore, it is recommended that the Half-Rate Service feature bepreferentially enabled to expand network capacity and VAMOS be enabled only when network

capacity needs to be further expanded. In addition, VAMOS is not recommended to be deployed fortelecom operators who are very concerned about speech quality.


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HW Efficiency % & SAIC penetration(VAMOS MS)

This graph shows Hardware Efficiency( Saving network resources(Number of required TRXs)


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SAIC penetration(VAMOS MS)

This graph shows mobile support SAIC(VAMOS I) This graph shows mobile support SAIC(VAMOS I) hourlyas sometime the penetration touching 100%


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TCH Drop rate vs DL/UL Quality 0 %

When Two call multiplex on one slot the user quality effected and probability of call drop increase with VAMOSfeature this due to mobiles either support VAMOS or not.


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TCH Congestion Rate,CSSR and HOSR

Whenever VAMOS activated the congestion in network reduced especially for loaded traffic network and such KPIlike CSSR and HOSR can be kept if properly parameter sets for VAMOS on cells and other part of networkselements


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Conclusion

According to test the settings in term of effective parameters make VAMOS traffic despite the Quality degradationare :-

Network must have high penetration for SAIC allowed .

Proper parameters sets as below are the most effective one.

1- Allow Multiplex for Unknown SAIC MS to be ON

2-

3-

Parameter Value

DL RX Qual Thres of Terminal Identify 10

UL RX Qual Thres of Terminal Identify 10

DL Rx Qual. Thres. of Established Calls 10 to 30

UL Rx Qual. Thres. of Established Calls 10 to 30

UL RX Bad Qual. Demultiplex Thres. 30 to 50

DL RX Bad Qual. Demultiplex Thres. 30 to 50

Parameter Value

Channel Multiplex Load Thres. 25 to 50

Load Thres. of Channel Demultiplex 0 to 25

Huawei VAMOS Trial Test

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