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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…