The Differentiated Techniques to Co-Deploy in

the Macro and Small Cell Layers

SK Telecom / December 4, 2012

Changyoung Kim

5th Small Cells Americas, Dallas, TX

WINNER

1

Table of Contents

I. LTE Traffic and Service Usage

II. LTE Small Cell Solutions

III. Unique Solutions

IV. Future Plan for the Small Cell

2

Data Service Usage Pattern & Growth Rate

Ⅰ. LTE Traffic and Service Usage

SKT’s Mobile Traffic Trends

Dramatic increase of mobile traffic

- Due to the increasing number of smartphone users and

the spread of LTE

July 2010 Dec. 2010 June 2011 Dec. 2011 June 2012

297

2,303

5,880

10,447

16,657

(Unit: Terabyte / Month) Multimedia (34.7%)

Web Portal

(33%)

App.

Market

(13.6%)

Etc.

(13.5%)

SNS (5.2%)

[ LTE Traffic Volume Ratio, June 2012 ]

Growth Rate (After Oct. 2011)

Multimedia x 115

Web Portal x 96.7

App. Market x 31.9

SNS x 135

• SKT has acquired over 6M subscribers in just 1.3 years after launch, firmly establishing it’s position

as the LTE Market leader in Korea and playing a key role in popularization of LTE

• With the spread of LTE smartphone users, usage patterns such as Mobile multimedia, SNS have

been dramatically increased and will keep growing at a rapid pace

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II. LTE Small Cell Solutions

Interference Management SKT LTE Femto

Internet

Coverage Extension

Hot zone Data Offloading

Aggregation/ Security GW

Macro Data Offloading

EMS/SON Server

Macro eNB Info.

Femto-Cell ICIC Server

Premium In-building Service

Capacity enhancement/data offloading in in-building

hot zones

- Connected to LTE Core via Public broadband N/W

- IPSec provides security functions

High-quality mobility and flexible N/W configuration

by adapting Femto GW

Femto-Cell ICIC server will provide the performance

enhancement in the cell edge

- Frequency selective scheduling and power control will be

applied from information exchange between Femto to Femto

or Femto to Macro

Rel-8/9 CoMP (DL Coordinated Scheduling) has

been applied based on A-SCAN (Cloud-RAN)

- UL-CoMP trial with interference rejection combining in Oct.

2012, and commercialization will be in 2013

- Evolution to Rel-11/12 CoMP (Joint Transmission/Dynamic

Point Selection)

eICIC has been trialed in July 2012, and plan to be

commercialized in 2013

• Small cell is the most powerful way to increase N/W capacity, but efficient interference management

schemes should be supported

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III. Unique Solutions 1. X2 I/F between Macro and Femto

• Although X2 I/F between Macro and Femto are being developed in 3GPP, SK Telecom already

commercialized LTE Femto with X2 I/F on June, 2012

• With X2 I/F, Femto has secured a stable H/O between the Femto and Macro by processing a

greater number of H/O message and increasing the rate of H/O success by 6.5%P

LTE Femto Network Topology

X2 I/F Management

- X2 setup and eNB configuration update

- Information management used for SON and

connection process on SCTP between Femto –

FGW – eNB

X2 Mobility Management

- Process of H/O messages(Request/Ack/Failure)

- UE X2AP ID mapping, E-RAB Setting

Transfer X2 Load Information

- Broadcast load information of Macro to all Femtos

included in FGW

X2 User Plane

- DL data forwarding between Macro – Femto

- TEID & IP mapping

Main Features of X2 FGW

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III. Unique Solutions 2. Interference Mitigation Solution

• A centralized interference coordination system and femtocells with proprietary message interface for

ICIC

• Coordinates inter-cell interference between femtocells with resource partitioning

• Protects macrocells downlink/uplink from interference of femtocells

Femto to Macro Interference Control Femto to Femto Interference Control

Flexible ICIC Interface

- Resource partitioning for ICIC can be operated in time or

frequency domain

- Depending on backhaul latency and server load, FFR can

be applied in both static and dynamic modes

FFR based ICIC Scheme

- FICS assigns sub-band sets for CCU and CEU after

considering the relation between adjacent Femtos

Femto Tx Power Control

- Rough power control based on periodic N/W listening

- Fine power control based on CQI statistics from F’s UEs

- Rapid power adjustment for Macro UE protection based on

abrupt UL interference level

UL Power Control Parameter Adjustment

- M’s UL protection based on X2(HII, OI) message listening

Subband for CCU

Subband for CCU

Subband for CCU

Cell-A

Cell-B

Cell-C

Subband for CEUpwr

FICS

(Femtocell IC System)

HeNBMacro eNB

Adjacent

eNB Info.

DL/ UL Power

Control Parameters

Uplink High

Interference/

Overload

Information

X2

Interface

Macro UEMacro UE

Macro eNBs

Femto Gateway

(X2 proxy)

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III. Unique Solutions 3. Smart Interworking Femto with SON

• A centralized optimization system of H/O and coverage parameters between Macro and Femto (&

Femto and Femto)

• A centralized management system to configure PCI and to avoid RSI collision between Macro and

Femto (& Femto and Femto)

Interworking Process between Femto and SON Server

SKT SON FMS Macro EMS Operator

Input the default

PCI/RSI and

longitude/latitude for

new Femto

After Femto starts up

with initial information,

register neighbor list

using sniffing

Transfer data

what gets

during work

sniffing

Register PCI of the

Femto in the Macro

Neighbor

Assign PCI/RSI

Update PCI/RSI

Transfer Sniffing

and PCI data

Femto

Transfer Initial PLD

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III. Unique Solutions 4. FRS(Femto Repeater System)

• FRS can be used to extend in-building coverage without interference between Femtos

• It has a system having separated DU and RU(Advantage to extend coverage)

• It has no H/O zone within RUs(Advantage at the existing Femto cell edge)

• When an operator wants to change the service frequency, it is supported just by replacing RU

Topology using FRS Topology using only Femto

Conventional

- It can service only small cell

- Interference rise between Femtos

- Low data speed at the overlap region

- Bad RF quality frequent H/O between Femtos

Advanced

- It can service relatively large size cell

- There is no interference between RUs

- Uniform data speed in the most of service region

- There is no H/O between RUs

8

’12.1Q ’12.2Q ’12.3Q ’12.4Q 2013 ~

850MHz LTE Femto

commercialization

FICS(Femto Interference

Coordination System)

Carrier Aggregation

planned

World’s first LTE Femto

commercialized in June 2012

3GPP Rel.9 based(32UE, 2x2

MIMO, Dual-band Wi-Fi, PoE,

NTP)

World’s first FICS trialed in

September 2012

Verified improved T/P between

Femtos(25%), between Femto

– Macro(15%)

Development in 2013

speed and capacity improvement

by binding dual bandwidths

IV. Future Plan for the Small Cell

: Trial

: Commercialization

LTE Femto

• SK Telecom commercialized world first LTE Femto cell in 2012 and plans to launch Carrier

Aggregation technology at the Femto in 2013

LTE Femto

(Residential)

FRS

Thank You!