Modularized Two-Stages Vertical Handoff Scheme in Integration of WWAN and WLAN
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Transcript of Modularized Two-Stages Vertical Handoff Scheme in Integration of WWAN and WLAN
Modularized Two-Stages Vertical Handoff Scheme
in Integration of WWAN and WLAN Shimin Li Ying Wang
Presented byShimin Li E&CE750
Second part of presentation of our report
Recall the first part of presentation
Motivation and Objective Overview of WWAN and WLAN Integration of WWAN and WLAN Modularized Vertical Handoff Scheme
Decision module
Presentation Overview
Mobile IP Vertical Handoff Delay Related works Solutions Modularized Vertical Handoff Scheme
Action Module Performance Analysis Discuss Conclusion
Mobile IP
This diagram comes from ECE750 lecture slides
Mobile IP cont’d
Basic Mobile IP MN has a permanent IP address When moving to foreign network, MN detects a FA
and obtains a CoA, and registers the CoA with HA HA tunnels all packets of MN to FA or MN itself
using the CoA CoA can be Foreign Agent CoA or Co-located CoA
Mobile IP cont’d
This diagram comes from ECE750 lecture slides
Mobile IP cont’d
Optimized Mobile IP CN requests the current location of MN from HA. HA
returns the CoA of MN via an update message. Then CN caches the CoA and send packets directly to the current foreign agent FA or MN itself. Encapsulation of data for tunneling to the CoA is now done by CN, not HA
Solve triangular routing problem
Mobile IP cont’d
Assumption about MIP Vertical handoff scheme is based on MIPv4 CoA is a Foreign Agent CoA, not Co-located CoA
Vertical Handoff Delay
Vertical Handoff Delay cont’d
Definition Vertical handoff delay = D1 + D2 + D3
Analysis D1 depends on movement and is out of control, we assume
that D1 is relatively small D2 and D3 can be minimized using intelligent handoff scheme
Related work
Proposed mechanisms addressing reducing delay H. Park et al. reduced delay by adding two structures to the
integration: Mobile Agent and Subnet Agent S. Sharma et al. introduced OmniCon: a MIP-based vertical
handoff system for integration of WLAN and GPRS[2] Ye Min-hua et al. used RSS triggering and multi-tunneling to
address WLAN/GPRS integration based on Basic MIPv4[3] Q. Zhang et al. proposed a subscription/notification service in
vertical handoff system based on MIPv4 to handle simultaneous movements and provide transparency to NAT[4]
Solutions For minimizing D2
Sense physical and MAC layer For minimizing D3
Divide handoff procedure into two steps Perform advance registration Allow MN to communicate with FAnew while still connected to FAold
For reducing packet loss Copy and tunnel packets for MN to FAnew even before handoff has
been finished For easy implementation and application transparency
Vertical handoff is based on MIP Only modify the entities of MIP such as MN, HA, and FA Modularize the handoff system
Modularized Vertical Handoff Scheme
ModularizationDecision ModuleAction Module
Recall the Decision Module
Trigger handoff actions How?
By sending messages to Action Module: Per-handoff message Handoff message
Action Module
Perform vertical handoff actions Per-handoff actions Handoff actions Undo actions
Triggered by messages from Decision Module
Action Module cont’d
Per-handoff actions Triggered by Per-handoff messages Four scenarios:
From WWAN to WLAN based on Basic Mobile IP From WWAN to WLAN based on Optimized Mobile IP From WLAN to WWAN based on Basic Mobile IP From WLAN to WWAN based on Optimized Mobile IP
Action Module cont’d
Action Module cont’d
Action Module cont’d
Action Module cont’d
Action Module cont’d
Handoff actions Triggered by Handoff messages Four scenarios:
From WWAN to WLAN based on Basic Mobile IP From WWAN to WLAN based on Optimized Mobile IP From WLAN to WWAN based on Basic Mobile IP From WLAN to WWAN based on Optimized Mobile IP
Action Module cont’d
Action Module cont’d
Action Module cont’d
Action Module cont’d
Action Module cont’d
Undo action Undo per-handoff action How?
MN sends undo message to HA via FAnew. After receiving the message, FA or CN stops copying packets and tunneling them to FAnew, and FAnew cleans its buffer
After that MN communicates with it original network normally When?
The timer in Action Module reaches T0, a constant Whenever starting per-handoff action, the timer starts After handoff action or undo action, the timer stops and is reset to zero
Performance Analysis
Purpose Verify contribution of two-stage scheme Verify contribution of physical layer and MAC layer sensing
Approaches Compare with other mechanisms
Tools The network simulator: NS-2, or Writing a specific simulator using Java or Matlab
Discuss
Limitations Not compatible with Network Address Translation (NAT)
MN behind NAT Gateway allocates a private IP address MN has no routable IP address so it is impossible to establish
a link to HA Not support simultaneous movement
Possibility is very low
Extension to Mobile IPv6 CoAs are co-located, no FA needed Adding an additional server at router to provide data buffer and
forward the buffered packets to MN as the FA in MIPv4
Conclusion
Physical layer and MAC layer sensing decrease latency contributed by detecting new FA and obtaining new CoA
Two-stage mechanism significantly reduces latency by doing some registration work in advance
Multi-tunneling decreases packet loss, and cost due to multi-tunneling can be very low since multi-tunneling lasts very short
Modularization provides a easy implementation Only modification of Mobile IP entities provides high compatibility
and transparency to application The vertical handoff scheme can be applied to real-time application
Selected references
1. Hyosoon Park, Sunghoon Yoon, Taehyoun Kim , Jungshin Park, Misun Do, and
Jaiyong Lee; “Vertical Handoff Procedure and Algorithm between IEEE802.11 WLAN and CDMA Cellular Network”
2. Srikant Sharma Inho Baek Yuvrajsinh Dodia Tzi-cker Chiueh; “OmniCon: A Mobile IP-based Vertical Handoff System for Wireless LAN and GPRS Links”
3. M.Ye, “The mobile IP handoff between hybrid networks”, IEEE, 2002
4. Q. Zhang, C. Guo, Z. Guo, and W. Zhu, “Efficient mobility management for vertical handoff between WWAN and WLAN” IEEE Commun. Mag., vol. 41, pp. 102–108, Nov. 2003
Thanks