Ting-Huei Lin, Ph.D.Email: linth@cht.com.tw

Senior Engineer

Mobile Business Group, Chunghwa Telecom Co., Ltd.

Impact on the Capacity and Performance

with the Implementation of a Second

Carrier in 3G Network

2/20

Contents

CHT Mobile Network Status

HSDPA Planning Strategy

Key Impacts of HSDPA

Conclusions

3/20

Taiwan population

Mobile Market in Taiwan

Highly competitive mobile market

� Many systems and operators within 36,000 km2

� Penetration rate is more than 100%.

GSM/WCDMA is the dominant system.

All WCDMA systems had launched HSDPA service.

GSM WCDMA WCDMA WCDMA WCDMA HSPAHSPAHSPAHSPAcdmacdmacdmacdma

2000200020002000PHSPHSPHSPHS WiMaxWiMaxWiMaxWiMax

CHT VFDD:2x15MFDD:2x15MFDD:2x15MFDD:2x15M

TDD: 5MTDD: 5MTDD: 5MTDD: 5MV - - -

TWN VFDD:2x15MFDD:2x15MFDD:2x15MFDD:2x15M

TDD: 5MTDD: 5MTDD: 5MTDD: 5MV - - -

FET VFDD:2x15MFDD:2x15MFDD:2x15MFDD:2x15M

TDD: 5MTDD: 5MTDD: 5MTDD: 5MV - - v

VIBO -FDD:2x10MFDD:2x10MFDD:2x10MFDD:2x10M

TDD: 5MTDD: 5MTDD: 5MTDD: 5MV - - -

APBW - - - 2x20M2x20M2x20M2x20M - -

FITEL - - - - v -

…+5 - - - - - v

Operator

System

4/20

Chunghwa Telecom Mobile

CHT- the largest integrated telecom operator in Taiwan

� Fixed, mobile, Internet, satellite, …

The largest mobile operator in Taiwan

� Subscribers > 9.2 millions

� Mobile market shares 34%

GSM900/1800 & WCDMA/HSPA network

Subsc

ribers

(m

illi

n)

Source: NCC

5/20

CHT 3G Migration

As the leading 3G operator in Taiwan, CHT aggressively migrates 3G network to provide the best service to our customers.

Following network migration, CHT simultaneously promotes new devices, such as CHT9000, Diamond, iPhone…, etc.

2005 2006 2007 2008 2009 2010

WCDMA HSDPA HSUPA HSPA+

CHT9000CHT9100 iPhone

6/20

3G Traffic Growth

3G traffic and network load increase quickly� Most of increasing 3G traffic is PS data

� Traffic of high speed data increases ~ 30% per quarter

PS flat rate and smart phone induces heavy data traffic� Under keen market competition, all 3G operators in Taiwan

provide PS flat rate service

HSPA increases network capacity and traffic loading

7/20

Mobile Coverage Solutions

GSM/GPRS offers wide-area seamless coverage

3G/HSPA offers broadband coverage

EDGE compensates 3G broadband coverage hole

Repeater extends coverage range

Home/ public WiFi provides broadband access for indoor/hotspot

UrbanUrbanRuralRural SuburbanSuburbanUrbanUrban

GSM/GPRS

3G/HSPA3G/HSPA

repeater repeater

repeater

WiFi

WiFi

WiFiWiFi

EDGE EDGE

8/20

Carrier Allocation for CHT 3G Scenario Application Status

Single Carrier

F1(R99)

•Special enterprise area

•For voice and SMS only

area

~0.5 %

Single Carrier

F1(R99+HSDPA)

•Rural and low traffic area

•For coverage 28 %

Two Carriers

F1(R99)

F2(HSPA)

•Urban and sub-urban area

•For performance and

capacity

71 %

Two Carriers

F1(R99+HSPA)+

F2(HSPA)

•High traffic hot spot

•For capacity ~0.5%

Three Carriers

F1(R99)+

F2(HSPA)+

F3(R99+HSPA)

•Extra high traffic hot spot

•For capacity <0.1%

9/20

Key Impacts of HSDPA

Source: Tommi Heikkilä

� Ec/No� Code� Mobility

10/20

HW and SW Impact

More HSDPA carriers enabled, more hardware resources

demanded

� Enabling HSDPA must occupy a large block of CEs

� More amplifier power and RF device allocated for multi-carriers,

Must upgrade many new SW features

� Some functions are cost by traffic capacity

Following HSPA performance migration, investment to HW and SW upgrade will be increasing accordingly.

HW e

xpansion

SW li

cense

fee

capacity

Co

st

HW+SW migration

Time

Revenue

Net

wor

k co

st

Tra

ffic

vol

ume

&

11/20

HSDPA Power Allocation

HSDPA power can be set to be fixed or dynamic power allocation.

HSDPA power setting depends on coverage and traffic strategy.

� High power -> high throughput and coverage

� Priority to HSDPA traffic or to R99 DCH traffic.

Dedicated 2nd carrier can allocate more power to HSDPA.

-3 -6 -9 -12 -15Ec/No

Th

rou

gh

pu

t

Fixed power Dynamic power

12/20

Ec/No Impact

Enabling HSDPA will increase average Node B power and degrade Ec/No.

To achieve good performance, all RRM functions referred to Ec/No need to be optimized.

-15

-12

-9

-6

-3

0

4 8 12 16 20Ptx_total (W)Ptx_total (W)Ptx_total (W)Ptx_total (W)

Ec/N

o (

dB

)E

c/N

o (

dB

)E

c/N

o (

dB

)E

c/N

o (

dB

)

1-cell

2-cell_X

3-cell_X

EnableHSDPA No

-do

min

an

t cell a

rea

HSDPA

Throughput

Ec/No

13/20

Iub Transport

Double HSDPA speedcapability, only increase

20~40% average throughput.

HSDPA demand more transport bandwidth.

Traditional E1 is not the economic and efficient transport for HSDPA traffic.

HSDPA

traffic

Source: Harri Holma

~20%

~40%

14/20

CHT Mobile Backhaul Strategy

Initial solution: increase E1 to support HSDPA traffic

� Now mainly for low peak-rate site (< HSDPA 3.6M)

Today solution: E1+Ethernet hybrid backhaul

� E1 for CS traffic, signaling and synchronization

� 10/20/30M NG-SDH for PS

Next step: all-IP transport

� Need new version Node B or extra-interface module

� Need synchronization source

TDMTDM

NG SDHNG SDH

E1

Ethernet

E1

GE

STM-1

MRMR

TDMTDME1 E1

PTN PTN oror NG SDHNG SDHEthernetGE

15/20

Code Resource

Code resource will be insufficient for high rate HSDPA

� Common channels and R99 traffic, as well as HSDPA, need to occupy code resource.

� Code congestion rate will increase after enable high rate HSDPA

HSDPA for shared carrier is often down-rated by code congestion.

Dedicated carrier can provide more codes for HSDPA

Codes for HS-DSCHCodes for DCH,

HS-SCCH

16/20

Mobility Parameters

Mobility parameters planning become more complex after enabling HSDPA

� Ec/No is suddenly degraded by activating HSDPA

� R99 DCH is SHO, but HSDPA is HHO.

� HSDPA link-budget is different from R99

Traffic distribution between multi-carrier has to be adjusted by mobility parameters

� Direct HSDPA UE to HSDPA carrier

� Load balance for multi-carrier

Mobility parameters setting will be depended on carrier scenario, network function and traffic strategy

17/20

Network Mobility Optimization

1st carrier for idle mode, CS and R99 PS

� Setting cell reselection parameter to push all UE in idle mode to 1st carrier.

2nd carrier for HSDPA

� HSDPA UE make PS call is re-directed to 2nd carrier

2G

3G F2 (HSPA)

3G F1 (DCH)

idle voice data

: R99 UE

: R5/R6 UE

18/20

Performance and Capacity

Activating 2nd carrier for HSDPA traffic can improve the HSDPA throughput

� Dedicated carrier provide more power and codes

Voice call performance is improved after removing HSDPA loading in shared carrier

� Less Ec/No degraded by loading

Shared to Dedicated CarrierShared to Dedicated CarrierShared to Dedicated CarrierShared to Dedicated Carrier

19/20

Comparison for Shared and Dedicated Carrier

Shared Carrier Dedicated Carrier

Scheme

Advantage - Faster Deployment

- Cost Efficient

- Simpler parameter planning

-Minimum Impact to existing R99

performance

-Better HSDPA performance

Dis-

advantage

-Less capacity improvement

-Code tree limitation

-Impact exist Rel 99 performance

(Ec/No degradation)

-Additional HW & site re-

commissioning required

-More complex parameter

planning

Recommen

ded Area

Less capacity critical area

(rural area)

High capacity area

(Dense Urban, Hot Spot, Indoor,

20/20

Conclusions

Enabling HSPA will enhance QoE of customers, but increase CAPEX and OPEX.

Dedicated HSDPA carrier can get better network performance, mainly for HSDPA throughput and R99 QoS.

Market competition and quickly increasing PS traffic drive the demand for HSPA. The benefits for launching HSPA still depend on marketing and sales’ strategy.