UMTS Access and Retainability Performance Improvement Solution 01%2820120709%29

HUAWEI TECHNOLOGIES CO., LTD.

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Huawei Access & Retainability performance improvement Solution

Page 2HUAWEI TECHNOLOGIES CO., LTD.

Author / ID Wang Li/ 00132365

Co-author / ID Li Xiao/00148426

Approver / ID Zhao Xinchun/146689

Description

In this slide, it describes the overview solutions: Access performance solution, such as retainability performance solution, Access improvement solution in resource congestion to expansion carrier in hot spot sites, Access improvement solution in Network structure(RAB DRD Rollback), retainability improvement solution in signaling optimization(SHO procedure optimization and PS 8k in CS call setup), Retainability improvement solution in signal fluctuate(RRC Re-establishment), Retainability improvement solution in weak coverage(HSUPA fall back to R99 DCH).

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present


The changing of network bring the changing of Access & Retainability performance

Analysis the cause of the poor performance decreasing

Provide the solution to improve the Access & Retainability performance. It will improve user’s experience.

Challenge

Quality

Capacity

CoverageNetwork’s KPI

The Key performance of the network affect the user’s experience directly

There is a coupling relation in network’s capacity, coverage and quality.

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10000001200000

527346602610

866585

1110467.5

User Number Increase

Use

r N

um

ber

User number increase sharply in short-time brings the network heavy load, Influence network’s capacity & coverage

Average US Cell phone User iPhone

Voice Call 70%

SMS15%

Music 2%Games 3%

Internet 3%Others 3%

Voice Call40%SMS14%

Others 3%Internet 11%

Use more

Games 9%

Music 11%

E-mail 13%Source: AT&T

User behavior changing bring the traffic modelchanging: from Single service to combine service. Influence network’s coverage & quality.

The Access & Retainability performance degrade and will be worse than before

Optimization


Solution OverviewAccess performance solution overview

Weak Coverage Network structure resource congestion

Signaling optimization

RRC

RAB

RRC redirection based on coverage

Select & reselect parameter optimization

RRC channel type optimization

Power control optimization in Open-loop

FACH power optimization

Soft Handover optimization in IUR

PS E2D Based on Coverage

Downlink max power optimization

RLC parameter optimization

Activating timer optimization in weak coverage

LAC optimization Camp on strategy

optimization for IDEL user Inter-frequency / intra-

frequency / inter-rat reselection optimization

Redirection due to resource congestion

Site/ carrier expansion Multi-sector FACH congestion

optimization CE overbooking Dynamic CE Power resource access

control optimization UU capacity optimization hardware expansion NODEB Dynamic code

RRC setup command repeat optimization

Timer and parameters optimization for IDEL user

Timer optimization in signaling process

RRC message length optimization

Camp on strategy optimization for IDEL user

Access strategy optimization RAB DRD Rollback DRD trigger condition

optimization RB setup channel type

optimization

Uplink total ENU optimization Access control threshold

optimization CE overbooking Dynamic CE NODEB Dynamic code Power resource access

control optimization UU capacity optimization CS RAB prefer Site/ carrier expansion Multi-sector Hardware expansion HSPA max user number

optimization

Timer optimization in signaling process

Activate timer optimization Signaling overlap

optimization Active Radio link re-establish 1A measure parameter carry

on system information block


Solution OverviewRetainability performance solution overview

Weak Coverage

Network structure

RF fluctuate Heavy Cell

load Signaling

optimization

CS

PS

SHO trigger condition optimization


RL synchronization optimization

Timer and parameter optimization for connect mode

Downlink max power optimization

PS DCH rate optimization in CS+PS combine service

PS channel type optimization in CS+PS combine service

HSDPA CQI feed back cycle optimization in CS+PS combine service

Activating timer optimization in combine service

SHO trigger condition optimization


Timer and parameter optimization for connect mode

E2D based on coverage HSDPA server cell update

optimization HUSUPA TTI switch

Multi-carrier strategy optimization

Inter-frequency handover strategy optimization

2G&3G interaction strategy optimization

Handover parameter optimization in combine service

IUR-relocation optimization in combine service

Multi-carrier strategy optimization

Inter-frequency handover strategy optimization

PS inactive timer optimization

PS state transfer parameter optimization

FACH congestion optimization

Ratio re-establish in Downlink synchronization fail

Active Ratio re-establish

Ratio re-establish in Downlink synchronization fail

Active Ratio re-establish

HSDPA CQI feed back cycle dynamic modification

HSUPA PO optimization HSDPA available power

optimization

HSDPA CQI feed back cycle dynamic modification

HSUPA PO optimization HSDPA available power

optimization SCCPCH expansion

State timer in signaling process optimization

Active Ratio link re-establish in UE SRB reset

Neighbor parameter optimization

Periodical DRD optimization in CS+PS combine service

DCCC strategy optimization in CS+PS combine service

HSUPA TTI optimization in CS+PS combine service

Inter-frequency handover rollback

State timer in signaling process optimization

Active Ratio link re-establish in UE SRB reset

Neighbor parameter optimization


Access improvement in weak coverage – RRC Redirection based on coverage

Scenario/Challenge

Access improvement

• RRC setup request sent with EcIo less than -18dB occupies less than 2% of all attempt number, while occupies nearly 20% of all failure number.

Benefit/ Influence

Theory

• Normally, 2G has a more better coverage than 3G. Therefore, in these area, RNC to redirect UE which sent RRC setup request with EcIo less than -18dB to 2G to obtain better service.

• Improve RRC access successful rate in weak coverage• Improve RAB access successful rate follow on RRC• Influence:

• Nome

Case

From simulation, the RRC setup successful rate is very low while EcIo less than -18dB

• None


Case

Access improvement in resource congestion – Expansion carrier in hot spot sites

With 3rd carrier activation

With 3rd carrier activation

Access improvement

Scenario/Challenge

• UU resource such as power, code and so on is congestion frequently

• Optimization parameters had already been executed

Benefit/ Influence

• Reduce the UU congestion in hot spot sites• Influence:

• Nome

• After expansion, both RRC and RAB fail due to congestion solved.• The traffic of hot spot sites increase


Access improvement in Network structure – RAB DRD Rollback

CS Preferred Carrier; Cell1

PS Preferred Carrier; Cell2 HSDPA Service

Single Carrier2nd Carrier activated

RAB DRD Rollback

Access improvement

Scenario/Challenge

• RAB setup fail due to Direct Retry Decision between multi-carrier for service steering or load balancing.

Benefit/ Influence

Theory

• In RB SETUP signaling process with DRD, if UE can not synchronize with UTRAN, it will send back RB SETUP FAIL to RNC. Then, RNC will send RB SETUP to the cell which has radio link with UE before and setup the RB in this cell to avoid RB setup fail.

• Improve RAB access successful in multi-carrier sites• Influence:

• Nome

Case

After executing RAB DRD Rollback, the PS RAB success rate improve obviously

If Physical channel failed to synchronize in cell2, it will retry in cell1 again to improve RAB assignment success rate.

4/2

4/3

4/4

4/5

4/6

4/7

4/8

4/9

4/10

4/11

4/12

4/13

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4/17

0

200000

400000

600000

800000

1000000

97.50%

98.00%

98.50%

99.00%

99.50%

100.00%

PS RAB Establish Success Rate

VS.RAB.AttEstabPS.Cell VS.RAB.SuccEstabPS.Cell.Rate


Retainability improvement in signaling optimization - SHO procedure optimization Retainability improvement

Scenario/Challenge

• Call drop often occur in SHO process with poor RF condition.

Benefit/ Influence

Theory

• In poor RF condition, while voice call maintain survive but UU signaling will suffer lots of retransmission. if signal radio bearer reset, the RRC connection will be released. Therefore, during weak coverage scenario, useless UU signaling should be reduced as more as possible.

• Improve the call drop rate in SHO• Influence:

• Nome

Case

• After optimization the SHO triggering condition, the call drop rate improvement

If radio quality of neighboring cell is not good enough, there is no need to add it into active set.

-24dB -22dB -20dB0

20000

40000

60000

80000

100000

120000

0.00%0.05%0.10%0.15%0.20%0.25%0.30%0.35%0.40%0.45%

SHO triggering Optimization

Number of Release Voice drop rate


Case

Retainability improvement in signal fluctuate - RRC Re-establishment

OGRNC TBRNC STCRNC0.00%

0.10%

0.20%

0.30%

0.40%

0.50%

CDR before and after RRC Re-estab-lishment

Voic

e Ca

ll D

rop

Rate

Retainability improvement

Scenario/Challenge

• Certain cell missing in the Best cell’s neighbor list• The signal fluctuate scenario, such as in elevator

scenario or tunnel areas

Benefit/ Influence

Theory

• While lost signal of cell where UE connected, it will scan signal of new cell and send CELL UPDATE with Radio Link Failure cause in new CELL. Then the radio link will be reestablished in new cell. Therefore, the call will be kept on

• Improve the call drop rate in neighbor missing or signal fluctuating

• Influence:• During RL re-establish, there will be short

interrupt in communication

• After optimization, both three RNC’s call drop rate improved( The blue bar is the CDR before, the red bar is the CDR after RRC re-establishment

CELL B is not in CELL A’s neighboring cell list or signal fluctuating, UE will scan new cell .

CELL ACELL B


Retainability improvement in weak coverage– HSUPA fall back to R99 DCH

Downlink

Retainability improvement

Case

Scenario/Challenge

• The ratio of CS call drop in Multi-RAB scenario increasing stably as the CS&PS combination service increasing in the network. It infects the user’s experience.

Benefit/ Influence

Theory

• the coverage of multi-RAB is smaller than single service. It is easy to call drop for multi-RAB. Improve the coverage gap can improve multi-RABs call drop.

• As the signaling process in UU interface increasing introduced by PS service in CS&PS multi-RABs, the call drop possibility for multi-RABs is higher than single RAB. Optimization PS signaling can improve multi-RAB call drop.

• Improve the call drop rate in CS&PS Multi-RAB• Influence:

• The PS throughput during CS call will be lower than before.

• After optimization, HSUPA fall back to DCH during CS&PS multi-RABs, the CS call drop rate improvement

Coverage compare

PS signaling


Retainability improvement in signaling optimization – PS 8k in CS call setup Retainability improvement

Case

Scenario/Challenge

• Low PS traffic volume requires in CS&PS multi-RABs when the CS call setup with PS in PCH state.

• CS & PS HSPA introduce more call drop rate in the network

Benefit/ Influence

Theory

• When CS call happened with PS in PCH state, the RRC state will change to DCH state. For PS service in PCH state before, it means there is no data transfer, therefore, PS can be reconfigured to DCH 8k when state transfer from PCH to DCH. If user requires high PS traffic volume, PS can be reconfigured to HSUPA/HSDPA.

• Improve the call drop rate in CS&PS HSPA• Influence:

• none

• After optimization, the CS call drop in multi-RAB improve . Therefor the CS call drop rat improve


Input & Output

Access & Retainability performance

Analysis

Access & Retainability report

Access & Retainability performance analysis input & output

Access & Retainability performance analysis

Target signaling optimization analysis and solution

Reference script and influence clarify

Gain evaluation after solution executing

Analysis data

RNC configuration scrip

RNC performance date for a week

RNC PCHR logs including all Subracks for two hours

NODEB MML query result

NODEB resource group information

NODEB board configuration information

NODEB local cell information

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UMTS Access and Retainability Performance Improvement Solution 01%2820120709%29