Reducing Handover Delay in Next Generation Wireless Networks

1. Reducing Handover Delay in Next Generation Wireless Networks Linoh A. Magagula & H. Anthony Chan

2. Presentation outline • Introduction • Background • Problem Statement • Objectives • Methodology • Conclusion

3. WiMax UMTS IEEE 802.11 GPRS Introduction • NGWN  integration of heterogeneous but complimentary wireless access networks • Convergence over IP based infrastructure • Interwork & interoperate IP Backbone

4. NGWN provide ubiquitous network access • Anywhere, anytime • mobile users exploit a variety of access networks to meet their requirements, e.g. charging, QoS, etc. • Operators may • Offer compelling value-added services • Improve network capacity • Improve availability of services  Serve a wider set of users Happy network users

5. Challenge to the All-IP vision  vertical handover performance for ongoing real-time services continuous network access required during handover • High handover delay disrupts service continuity hence degrades perceived quality of communication of active connections reduce handover delay (optimize delay transparency)

6. IP configuration (CoA/DAD) Binding Update Movement detection Discovery Authentication • Handover delay: period of time that a handover procedure takes to complete • L2 and L3 delays • L2 delay is link technology specific • L3 delay can be reduced/optimized globally • Can not be avoided but can be optimized/reduced Handover delay

7. Background & Problem Statement • Various mobility management (MM) protocols proposed at different protocol stack layers to provide connection transparency, e.g. • Link layer MM protocols, SCTP, SIP, MIP, etc. • Various drawbacks, particularly in terms of handover,e.g. • MM protocols maintain mobility binding (reachability state) • bindings cannot seamlessly transfer & continue ongoing sessions without disruptions • Handover trigger based on signal strength

8. Background & Problem Statement • No network selection & handover initiation capabilities • Dependent on reactive manipulations of handover process, e.g. • Handover initiated when network change is detected @ IP layer • High handover delay • Not suitable for NGWN in their current form • Additional mechanisms required to enhance handover performance

9. Internet HA CN IP backbone Domain gateways AR AP L2 mobility MN Micro-mobility Macro-Mobility Towards handover delay reduction in NGWN • MIPv6 widely accepted MM protocol for NGWN • Inherently very long handover delay • To improve handover performance: split MM • Global (macro) • Localized (micro)

10. Domain gateway Tunnel Route or Binding Update AR Movement • Example Localized MM protocols • HMIPv6, Cellular IP, HAWAAI, etc. • Fast handover protocols, FMIPv6 proactive registration to reduce handover delay • Host-based

11. Utilization of L2 triggers/hints to enhance L3 handover procedure • Expense MIPv6 has to be dependent on underlying L2 technology hints not standardized • Various other works have been done to improve handover performance & network selectivity. However, • Handover delay still high for real time services • Handover (network) selectivity without impacting on handover delay is still a challenge

12. Objectives • To develop an intelligent architectural framework to improve vertical handover performance for real-time services • Reduce IP handover delay • To avoid perceptible service disruptions • Make faster & accurate network selectivity before handover • Perform optimal network selection among heterogeneous access networks in a short time scale • Investigate and evaluate tradeoffs (cost benefits)

13. LMA Route or Binding Update Tunnel MAG Movement Methodology • Intelligent synthesis of a network-based MM scheme (PMIPv6) and a technology-aware handover mechanism over a cross-layer design architectural framework

14. MIH Users Upper Layers (L3 and above) IP SIP MIPv6 Applications Commands Information Events Service Access Point (SAP) MIH FUNCTION Link-specific SAPs Events Commands Information LINK LAYERS (802.11, 802.16, 802.3, 3GPP, 3GPP2) • Utilization of IEEE802.21 MIH services enhance handover performance • MIES • Report dynamically changing lower layer events to upper layers • MICS • Enable MIH users to manage & control link behaviour related to mobility & handovers • MIIS • Facilitate network selection & effective handover decisions • Provide information about services & characteristics of neighbourhood

15. Internet CN LMA Info. server • MIH • • MAG3 • • MIH MAG1 MAG2 • • PoA MIH MIH PoA PoA MIH MN • MN & AR utilize MIH  updating & retrieval of information elements (info/MIIS server) • included • General info. & access network specific info. (e.g. cost, Qos, security, etc) • PoA specific info. (e.g. CoA, data rates, MAC addr., etc) • Stable IDs for attached MNs • Authentication information • Dynamic information • Each MAG up-to-date about surroundings

16. Information exchange done before hand • Proactive signalling deliberations • PMIPv6 domain under single administrative management  maintenance of info. server very feasible

17. Cross-layer design architectural framework to further improve handover performance • Protocol layers adapt & collaborate to optimize handover performance • Provision of faster signalling for network selection decision and handover initiation support • Handover delay is jointly optimized • facilitate relevant decision algorithms to react to corresponding handover-causing (initiation) scenarios for fast & accurate handover decisions

18. Any available network • Forced handover due to deteriorating signal strength or loss of resources • Parameters: RSS, battery power, resources, etc. • Best convenient network • Unforced handover mainly due to user preferences • Parameters: cost, available services, etc. • Active service-related handover • real-time & multimedia services • Parameters: network latency, data rate, QoS, etc.

19. New connection ready LMA DQ2 DR2 AAA/ Policy store DPBU DPBA DQ DR MAG DATTACH DRA MN time Handover delay Analysis of handover delay reduction • Typical PMIPv6 handover delay: • Attachment notification delay, DATTACH • Authentication delay, MAGMN, DAUTH • DAUTH = DQ + DR • Authentication delay, MAGLMA, DAUTH_2 • DAUTH_2 = DQ2 + DR2

20. Proxy Binding delay, MAGLMA,DBINDING • DBINDING = DPBU + DPBA • Router Advertisement delay, MGAMN, DRA • IP configuration delay, DCONFIG→0when MN is already in PMIPv6 domain per-MN-prefix • Duplicate Address Detection (DAD) delay, DDAD≈ 0when MN is already in PMIPv6 domain • Total handover delay • DPMIPv6=DATTACH+DAUTH+DAUTH_2+DBINDING+DRA

21. IP backbone CN LMA Info. server • MIH • • MAG3 • • MIH MAG1 MAG2 • • PoA MIH MIH PoA PoA MIH MN IEEE802.21-enabled PMIPv6 • During MN handover, new MAG would already know about attaching MN from relevant information element in server  DATTACH ≈ 0 • MN authenticated “before hand” when first discovered in information server  DAUTH →0  DAUTH_2 →0 • Hence, handover delay in our proposed scheme becomes • DPMIPv6_802.21=DBINDING+DRA

22. Conclusion • A handover delay reduction mechanism is proposed • Future work • Experimental evaluations through simulations • NS-2 and/or OPNET • Performance evaluation • Comparison with standardized fast handover schemes, e.g. FMIPv6 • Comparison with standard performance requirements for real time traffic

23. Publications • Papers accepted for publications • SATNAC 2008 (South Africa, September): Optimized Handover Delay in Proxy Mobile IPv6 using IEEE 802.21 MIH Services • WiMOB 2008 (Avignon, France, October): IEEE 802.21-assisted Cross-Layer Design and PMIPv6 Mobility Management Framework for Next Generation Wireless Networks • MILCOM 2008 (San Diego, USA, November): IEEE 802.21 Optimized Handover Delay for Proxy Mobile IPv6 • BroadCom 2008 (Pretoria, South Africa, November): Delay Transparency for Real Time services in PMIPv6

24. Thank You