Fast Handover Issues of Mobile Networks Korea University of Technology and Education Laboratory of Intelligent Networks Youn-Hee.

Fast Handover Issues of Mobile Networks

Korea University of Technology and EducationLaboratory of Intelligent Networks

http://link.kut.ac.kr

Youn-Hee Han

KRnet 20092

목차

1. Handover Technology & Example (WiMAX/WiBro 중심 )

2. Vertical Handover Technology

3. Seamless Handover Technology (Vertical Handover 중심 )

4. Performance Report & Discussion

KRnet 20093

1. Handover Technology & Example

KRnet 20094

Horizontal Handover

Frequency F1

Frequency F1

Frequency F1

Frequency F1

Frequency F1

Frequency F1

Cell 1

Cell 2

intra-cell handover inter-cell handover

inter-MSC handover

intra-MSC handover

Horizontal Handover 동일한 타입의 이동 통신 시스템 내에서의 이동 시에 발생하는

핸드오버 Intra-cell Handover

현재 서비스를 받고 있는 있는 셀 내에서 채널 ( 또는 타임슬롯 ) 을 바꾸는 기능 (e.g., 현재 채널의 품질이 저하될 경우 )

Inter-cell Handover 이동 단말이 일단 호를 설립하여 통화 중에 다른 셀로 이동할 경우 통화 단절

없이 서비스 기지국이 자동으로 바뀌어 끊임없는 통신을 가능하도록 하는 기능

KRnet 20095

Horizontal HandoverHorizontal Handover 관련 표준

3GPP 계열 GSM, GPRS, CDMA2000… 3GPP SAE(System Architecture Evolution)/EPC(Evolved Packet

Core) Architecture WiMAX/WiBro

WiMAX System Architecture IEEE 802.16e TTA - 휴대 인터넷 MAC 프로토콜 표준

Wi-Fi (WLAN) IEEE 802.11f (IAPP- Inter-Access Point Protocol) IEEE 802.11k (Radio Resource Management) IEEE 802.11r (fast roaming)

KRnet 20096

Vertical Handover

Public Internet

Home Agent

IPv4 (or v6) Access Network

802.11/Hotspot802.11/Hotspot

802.16e/Wibro802.16e/Wibro

3G/4G Cellular3G/4G Cellular

Access Router

Wireless Router

AAA

QoS Agent

vertical handover

Vertical Handover 서로 다른 타입의 통신망 사이를 단말이 이동할 때 자신이

유지하고 있는 세션을 끊김없이 유지하는 기능

KRnet 20097

Vertical Handover관련 표준화 단체

QoS support during handover

UTRAN WLANCDMA

2000WiMAX WLAN

IP based mobility support method

Network architecture

Access network selection algorithm

L2 Trigger for L3 handover

Power management for multiple interfaces

IEEE802.21/16g

IETF

3GPP 3GPP2

IEEE802.11u

연동 network

이종망연동을위한

요소기술

ITU NGN

KRnet 20098

Handover Support TechnologyHandover 에 대한 각 계층별 프로토콜

Layer 2 Mobility: 각종 통신망에 따른 고유의 프로토콜 존재 Reliable and quick Scanning & movement detection No impact on high-level protocol not capable for inter-access technology handover

Layer 3 Mobility: Mobile IPv4/v6, Proxy Mobile IPv6 Ideal candidates Link-layer independence IPv4/v6 Transport 및 IPv4/v6 Home Address Mobility 동시 지원

DS (Dual Stack)-MIPv6, DS-PMIPv6

Layer 4 ~ 7 Mobility: Mobile TCP, SCTP, SIP Per-application mobility support (Compatibility Problem) not practical

KRnet 20099

Handover Support TechnologyHorizontal Handover using one interface Intra-cell Handover - Inter-cell Handover

Inter-PHY/MAC Attachment Points - Inter-PHY/MAC Attachment Points/Layer 3 Network -

Vertical Handover using multi-interfaces Inter-cell (Heterogeneous Cell) Handover

Inter-PHY/MAC Attachment Points - Inter-PHY/MAC Attachment Points/Layer 3 Network -

IP Access Network

802.16802.16

④④⑤⑤

802.11802.11

HSDPA (or LTE)HSDPA (or LTE)802.16802.16

802.16802.16

Handover requiring IP handover

:

KRnet 200910

Handover Example - WiMAX/WiBroIEEE 802.16e (Hard) Handover Procedure

MNLayer 2

Serving BS

-BS1-

Target BS

-BS2-

Target BS

-BS3-

MOB_NBR-ADV

Scanning

MOB_MSHO-REQ(target=BS2,BS3) HO-Pre_Notification (MN ID, Capabilities, Required BW and QoS)

HO-Pre_Notification_Response (Ack, Available BW, Permitted QoS)

MOB_MSHO-RSP(Recmd.=BS2,BS3)

MOB_HO-IND(target=BS3)

IEEE 802.16d/e Network Re-entry Procedure

REG-RSP

RAS(Radio Access Station)ACR(Access Control Router) WSM(WiBro System Manager)AAA(Authentication, Authorization and Accounting)HA (Home Agent)

WiBro Network Architecture

RAS1 RAS2 RAS3

KRnet 200911

Handover Example - WiMAX/WiBroProxy Mobile IPv6 [IETF RFC 5213, August 2008]

LMM (Localized Mobility Management)

Domain

MAG

LMA

Proxy Binding Update/Ack. (PBU/PBA)

Control messages exchanged by MAG to LMA to establish a binding between

MN-HoA and Proxy-CoA

Home Network

Proxy Care of Address (Proxy-CoA)The address of MAG

That will be the tunnel end-point

IP Tunnel IP-in-IP tunnel between LMA and MAG

MAG

LMA: Localized Mobility AgentMAG: Mobile Access Gateway

LMA Address (LMAA)

MN’ Home Address (MN-HoA) MN continues to use it as long as

it roams within a same domain

That will be the tunnel entry-point

MN’s Home Network (Topological Anchor Point)

MN’s Home Network Prefix (MN-HNP)CAFE:2:/64

movement

KRnet 200912/46

Handover Example - WiMAX/WiBroProxy Mobile IPv6 over WiBro

KRnet 200913

2. Vertical Handover Technology

KRnet 200914

Vertical Handover Support Technology

Vertical Handover 지원 프로토콜 IEEE 802.21 MIH (Media Independent Handover)

각 통신망 별로 Verical Handover Execution 에 관한 표준 존재 3GPP 계열 – SAE/EPC 표준 IEEE 802.16g IEEE 802.11u

MIESMICS MIIS

KRnet 200915

IEEE 802.21 MIESMIES (Media Independent Event Service)

To provide link layer indication (trigger) to the higher layer State Change Events

MIH_Link_Detected indication MIH_Link_Up indication MIH_Link_Down indication MIH_Link_Parameters_Report indication

Predictive Events MIH_Link_Going_Down indication

Link Handover MIH_Link_Handover_Imminent indication MIH_Link_Handover_Complete indication

KRnet 200916

IEEE 802.21 MIESMICS (Media Independent Command Service)

It enables higher layer to manage and control link behavior relevant to handovers and mobility

Command Type MIH_Link_Get_Parameters MIH_Link_Configure_Thresholds MIH_Link_Actions (Power On) MIH_Net_HO_Candidate_Query MIH_MN_HO_Candidate_Query MIH_N2N_HO_Query_Resources MIH_Net_HO_Commit MIH_N2N_HO_Commit MIH_MN_HO_Complete MIH_N2N_HO_Complete

KRnet 200917

IEEE 802.21 MIESMIIS (Media Independent Information Service)

23年 4月 21日

Network Type

SSID/ Cell ID

BSSID Operator Security EAP Type Channel QoS Physical Layer

Data Rate

GSM 13989 N/A Oper-1 NA NA 1900 N/A N/A 9.6 Kbps

802.11n Enterprise 00:00:… Oper-2 .11i EAP-PEAP 6 .11e OFDM 100 Mbps

802.16e NA NA Oper-3 PKM EAP-PEAP 11 Yes OFDM 40 Mbps

Global Network Map

•List of Available Networks - 802.11/16/22, GSM, UMTS•Link Layer Information - Neighbor Maps•Higher Layer Services - ISP, MMS, ….

802.21 Information

Server

WMAN

WLAN

WWAN

KRnet 200918

Handover Example using IEEE 802.21 Service

23年 4月 21日

Procedure Summary Unit 1: Information Query

PoS MIIS

Unit 2: Threshold Configuration MN Serving PoS

Unit 3: Link_Going_Down Report I MN Serving PoS

Unit 4: Power On (Handover Ready) MN MN

Unit 5: Resource Availability Check Serving PoS Candidate PoSs

Unit 6: Link_Going_Down Report II MN Serving PoS

Unit 7: Resource Reservation Serving PoS Target PoS

Unit 8: Handover Commit MN Serving PoS

Unit 9: Link_Up Indication I Target PoS Target PoS

Unit 10: Resource Release Serving PoS Target PoS

MN Serving PoS

Candidate(Target)

PoS

Link Quality is

lower than Threshold I

Unit 1

Unit 2

Unit 3Unit 4

Unit 5

Link Quality is

lower than Threshold II

Unit 6

Target PoA/PoS is decided

Unit 7Unit 8

Link-specific Handover

Unit 9

Unit 10

MIIS

KRnet 200919

PMIPv6 using IEEE 802.21 Service

23年 4月 21日

PS (AAA)MN MAG

MN Attachment

AAA Query

with MN-IDAAA Reply

with Profile

PBU

PBA

RA Tunneling (after Tunnel Setup)

LMA MAG

PBU

PBA

AAA Query with MN-ID

AAA Reply with MN-ID

RA & Data

IEEE 802.21 MIH Procedure Unit 1~2IEEE 802.21 MIH Procedure Unit 1~2

MIIS

IEEE 802.21 MIH Procedure Unit 3~8IEEE 802.21 MIH Procedure Unit 3~8

Link-Specific Link-Specific HandoverHandover

MN Attachment

MN

IEEE 802.21 MIH Procedure Unit 9IEEE 802.21 MIH Procedure Unit 9

IEEE 802.21 MIH Procedure Unit IEEE 802.21 MIH Procedure Unit 1010

Tunneling (after Tunnel Setup)

KRnet 200920

Vertical Handover using PMIPv6 in 3GPP LTE/EPC

23年 4月 21日

PMIPv6 Deployment over LTE AAA/AAA/Policy ServerPolicy Server

UEUE S-GW/S-GW/(MAG)(MAG)

GTP-U Tunnel

P-GW/P-GW/LMALMA

IP-in-IP Tunnel

eNodeBeNodeB

P-GW: access gateway towards Packet Data Networks (similar to the GGSN)

- PMIPv6 will be mainly used for inter-system handovers (i.e. handovers between 3GPP and non-3GPP accesses)

Ref.] I. Guardini et al., “Mobile IPv6 deployment opportunities in next generation 3GPP networks,” 16th IST Mobile&Wireless Communication Summit, Budapest, Hungary 1-5, July 2007

Optional!

PMIPv6 scenario over LTE - 1/2 Vertical handover scenario

Vertical Handover using PMIPv6 in 3GPP LTE/EPC

LMA

KRnet 200921 23年 4月 21日

PMIPv6 scenario over LTE - 2/2 Vertical handover scenario

Vertical Handover using PMIPv6 in 3GPP LTE/EPC

LMA

KRnet 200922 23年 4月 21日

KRnet 200923

3. Seamless Handover Technology

Seamless HandoverSeamlessness = Fast + Smooth

Fast: 빠른 핸드오버를 통한 세션 단절 시간 최소화 Smooth: 버퍼링을 통한 패킷 손실 최소화 결국 핸드오버로 인한 패킷 손실 및 jitter 발생 최소화 목적

사용자에게 높은 QoS/QoE 제공

KRnet 200924

Seamless Handover – Layer 2Seamless Handover 관련 기술 (Layer 2)

각 표준별 기술 3GPP: Macro-diversity in UTRAN

WiMAX/WiBro Macro Diversity Handover(MDHO) Fast BS Switching (FBSS)

WLAN IEEE 802.11r (fast roaming)

KRnet 200925

• Multicasting of data via several physical channels

– Enables soft handover– FDD mode only

• Uplink– Simultaneous reception of UE data

at several Node Bs

• Downlink– Simultaneous transmission of data

via different cells

CNNode B RNC

Node BUE

Seamless Handover – Layer 3Seamless Handover 관련 기술 (Layer 3)

Mobile IPv6(v4) 에서 핸드오버 Latency 에 영향을 주는 요소 분석

KRnet 200926

[Latency Components] MD (Movement Detection) Latency

How to get “Router Advertisement” fast? DAD (Duplicate Address Detection) Latency

Constant time (1 sec.) How to shorten the constant time? Mobile IPv4 에서는 DAD 수행 불필요

BU (Binding Update) Latency It depends on the distance between MN and HA/CN

Standard MIPv6 (Reactive) L2 handover MD DAD RR & BUtime

> 2.5 seconds

Seamless Handover – Layer 3각 IP Handover 단계별 최적화 기술 (1/3)

Movement Detection (MD) Latency 최소화 Fast Router Advertisement(FRA)

draft-mkhalil-ipv6-fastra-05.txt Fast Router Discovery(FRD)

draft-ietf-dna-frd-02.txt

KRnet 200927

MN receives RA & discovers new subnet.

Link-specific Handover&

AAALink-Up

&Layer 3 (and

above) Communication

ReadyHow Long?

AR

AP/BS

MN

RA

Link-specific Handover&

AAA

AR

AP/BS

MN

RS RA

AR

AP/BS

MN

Link-specific Handover& AAA

RA

RA

[FRA]

[FRD]

Seamless Handover – Layer 3각 IP Handover 단계별 최적화 기술 (2/3)

DAD Latency 최소화 Optimistic Duplicate Address Detection (oDAD) – RFC 4429 (Aprial,

2006) Advance Duplicate Address Detection (aDAD)

Y.-H. Han and S.-H. Hwang, "Care-of Address Provisioning for Efficient IPv6 Mobility Support", Elsevier Computer Communications, Vol.29, No.9, pp.1422-1432, 2006.

KRnet 200928

MN receives RA

Link-specific Handover&

AAALink-Up

AR

AP/BS

MN

RS RA NS

Timeout (1 sec.)

BU to Home Agent

[oDAD 와 aDAD 를 통한 DAD 시간 제거 ]

Seamless Handover – Layer 3각 IP Handover 단계별 최적화 기술 (3/3)

Binding Update Latency 최소화 Hierarchical Mobile IPv6 (HMIPv6) - RFC 4140 (August, 2005)

KRnet 200929

[Standard MIPv6 (RFC 3775)]

[Optimized MIPv6]

MD Optimization RS+RA (RFC 3775 Optional) FRA (IETF Proposal), FRD (IETF Proposal)

DAD Optimization oDAD (RFC 4429) aDAD (A paper, IETF Proposal)

BU Optimization HMIPv6 (RFC 4140)

L2 handover MD DAD BU

time

Layer 2+3 Latency

L2 handover MD+DAD+BU

time

Layer 2+3 Latency

Seamless Handover – Layer 3IP Handover 전체 단계에 대한 최적화 기술 (1/3)

Fast Handovers for Mobile IPv6 (FMIPv6) - RFC 4068 (July 2005)

MD 와 DAD 과정을 Layer 2 핸드오버 전에 수행 라우터 간 터널링

KRnet 200930

MN PAR NAR

RtSolPr

PrRtAdv

FBU HI

HACK

FBACK FBACK

forward packets

FNA

deliver packets

L2 trigger

Disconnect

Connect

New 4 ICMPv6 Messages- Router Solicitation for Proxy (RtSolPr) - Proxy Router Advertisement (PrRtAdv) - Handover Initiate (HI) - Handover Acknowledge (HACK)

New 3 Mobility Messages- Fast Binding Update (FBU) - Fast Binding Acknowledgment (FBACK) - Fast Neighbor Advertisement (FNA)

Seamless Handover – Layer 3IP Handover 전체 단계에 대한 최적화 기술 (2/3)

Fast Handovers for Mobile IPv6 (FMIPv6) - RFC 4068 (July 2005)

각 네트워크별 Layer 2 프로토콜과의 교차 계층 최적화 Mobile IPv6 Fast Handovers for 802.11 Networks - RFC 4260 (Nov.

2005) Mobile IPv6 Fast Handovers over IEEE 802.16e Networks - RFC 5270

(June 2008) Mobile IPv6 Fast Handovers for 3G CDMA Networks - RFC 5271 (June

2008)

KRnet 200931

Layer 3(FMIPv6)

Layer 2(WiMAX/WiBro)

Cross-layering

Seamless Handover – Layer 3IP Handover 전체 단계에 대한 최적화 기술 (3/3)

Fast Reactive Handovers Optimization Combined MD and DAD + Network-based BU Y.-H. Han, J.-H. Choi, and S.-H. Hwang, "Reactive Handover Optimization in IPv6-

Based Mobile Networks," IEEE JSAC, Vol.24, No.9, pp.1758- 1772, September 2006

KRnet 200932

[Standard MIPv6 (RFC 3775)]

[Optimized MIPv6]

[Fast Reactive Handover Opti.]

[FMIPv6]

L2 handover MD DAD BU

time

Layer 2+3 Latency

L2 handover Optimized MD, DAD, and BU

time

Layer 2+3 Latency

time

MD BU+DAD Tunneling

Layer 2+3 Latency

L2 handover Combined MD&DAD + Network-based BU

time

Layer 2+3 LatencyRtSolPrPrRtAdv

FBU, HI, HAck, FBAck

FNA

Network-based Fast IP Handover네트워크 기반의 IP Handover 기술 및 최적화

기본 기술 Proxy Mobile IPv6 (PMIPv6) – RFC 5213 (Aug. 2008)

Base Protocol

IPv4 Support for Proxy Mobile IPv6 (Dual Stack-PMIPv6) draft-ietf-netlmm-pmip6-ipv4-support-12.txt (April 2009) IPv4 Transport 지원 + IPv4 Home Address Mobility 지원

핸드오버 최적화 기술 Fast Handovers for Proxy Mobile IPv6 (F-PMIPv6)

draft-ietf-mipshop-pfmipv6-04.txt (May 2009) 핸드오버시 라우터간 터널링 기술

Transient Binding for Proxy Mobile IPv6 (TB-PMIPv6) draft-ietf-mipshop-transient-bce-pmipv6-02.txt (March 2009) Make-before-break 핸드오버시 두 개의 인터페이스를 동시에 사용할 수

있는 기술

KRnet 200933

L2 handover MD ( 필요없음 ), DAD ( 생략가능 ), Network-based BU

time

Layer 2+3 Latency

[PMIPv6]

DS(Dual-Stack)-MIPv6, DS-PMIPv6 가 고려하는 응용레벨 시나리오

DS-MIP & DS-PMIP

CellularIP network

WLANIP Network

WiBro IP Network

RAS

LTE BS

WLAN AP

IPv4

IPv6

Private IPv4

NAT

AAA

DSMIPv6HA

IPv4

IPv6

IPv4 Application(VoD, IP-Phone…)

IPv6 Application(VoD, IP-Phone…)

DSMIPv6MN

34/66 DS-MIPv6 & DS-PMIPv6

KRnet 200935

4. Performance Report & Discussion

Comparison - MIPv6 vs. PMIPv6 over WLAN

Testbed Setup over IEEE 802.11

[MAG, LMA]Debian 3.1, Linux Kernel 2.6.10

[CN]Windows XP, SP2

[MN]Ubuntu 7.10

[VoD Streaming Software]VLC media server

[IEEE 802.1x Authentication] MD5/EAPoL + RADIUS

MIPv6 Software Stacks on HA, MN: MIPL (Helsinki University of Technology)

PMIPv6 Software Stacks on LMA, MAG: We have been implementing them since 2007 KRnet 200936 23年 4月 21日

Test Results with Heavy Traffic (presented at MobiWorld 2008

conference)

Encoding Rate: 2Mbps

UDP Throughput of MIPv6 UDP Throughput of PMIPv6

Comparison - MIPv6 vs. PMIPv6 over WLAN

KRnet 200937 23年 4月 21日

IPv4 Support for PMIPv6

PMIPv6’s IPv4 Support Testbed

IEEE 802.1x authentication 과정이 Linux 단말기 보다Windows 단말기가 훨씬 빠름

KRnet 200938 23年 4月 21日

F-PMIPv6 over WiMAX/WiBro

Network-based Fast IP Handover

Report(MN ID, BS3)

완벽한 Predictive Handover 가능KRnet 200939 23年 4月 21日

Network-based Fast IP HandoverPMIPv6 vs. F-PMIPv6

KRnet 200940

IEEE 802.21HO_Commit

IEEE 802.21Link-UP

Link-Link-specific specific

HandoverHandoverMN

PBU PBAck

LMA

Old MAG

New MAG

Total Handover Latency

Link-specific Link-specific

HandoverHandoverMN

PBU PBAck

LMA

Old MAG

New MAG

Total Handover Latency

HI HAck

Buffering

IEEE 802.21HO_Commit

IEEE 802.21Link-UP

PMIPv6

F-PMIPv6

F-PMIPv6 은 좋은 프로토콜인가 ?... 핸드오버 시간 동안 Router 간의 터널링

Network-based Fast IP Handover

MAG

LMAData Path during Handover

MAG

MAG

LMA

Data Path during Handover

MAG

- Frequent Tunnel Setup- Large tunneling overhead- High end-to-end delay- Decrease the overall throughput

개선

KRnet 200941 23年 4月 21日

Discussion (1/2)

표준에 근거한 단순한 Session Continuity 를 위한 최적의 Network-based IP Mobility 기술 조합 (Horizontal & Vertical Handover 의 경우 )

PMIPv6 + Dual-Stack Support F-PMIPv6 + Transient Binding ( 추가적으로… Localized Routing, GRE Tunnel Support, …)

Horizontal Handover 에서 추가적으로 고려할 사항 3GPP SAE/EPC Architecture 및 WiMAX/WiBro 의 L2 Handover 에

맞추어 Cross-layering 필요

Vertical Handover 에서 추가적으로 고려할 사항 IEEE 802.21 표준을 적극 활용한 Vertical Handover 지원 필요

Information Service, Event Service, Command Service

Fast-handover 에 대한 성능 개선 요구됨

KRnet 200942 23年 4月 21日

Discussion (2/2)

네트워크 주도의 Multiple Flow Management 연구에 대한 중요성 대두

KRnet 200943 23年 4月 21日

Horizontal Handover

Vertical Handover

Multiple Interface Management

Multiple Flow Management

A handover is initiated when mobile device exits the boundaries of an administrative domain. Single interface is used.

A mobile device does need to move in order to initiate a handover. Multiple interfaces are required, but use one interface at a time.

Simultaneous use of multiple interfaces and access networks. Association of an application with an interface

Ability to split individual flows between links with respect to the requirements of the flows and the user preferences

Co

mp

lexi

ty L

evel

WiMax

MAG

LMA

PBU(HI=1)

MAG

3G

MN3GWiBro

MAG

LMA

PBU(HI=1)

MAG

MN3GWiBro

WiMax 3G

다른 인터페이스를 통해 단순하게

새로운 세션 생성( 세션이동성은 없고… )

Mobile IPTVflow

VoIPflow

Mobile IPTVflow

VoIPflow

HTTPflow

MAG

LMA

PBU(HI=2)

MAGMAG

LMA

PBU(HI=1)

MAG

MN3G

새로운 인터페이스로 세션을 이동하고 있네 ?Vertical 핸드오버군 !

MN3GWiBro

VoIPflow

Mobile IPTVflow

WiMax 3GWiMax 3G

WiBro

Mobile IPTVflow

VoIPflow

이 두 가지 경우를 네트워크에서 어떻게 구분할 지…