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Tetsuya Arita and Fumio Teraoka

A Fast Handover Mechanism Using Cross-Layer Collaboration for Mobile Networks in High-Speed Trains. Tetsuya Arita and Fumio Teraoka Graduate School of Science and Technology, Keio University, Japan. Introduction. High-Speed Trains Passengers Spend long hours on a train Less transfer

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Tetsuya Arita and Fumio Teraoka

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  1. A Fast Handover Mechanism Using Cross-Layer Collaboration for Mobile Networks in High-Speed Trains Tetsuya Aritaand Fumio Teraoka Graduate School of Science and Technology, Keio University, Japan

  2. Introduction • High-Speed Trains • Passengers • Spend long hours on a train • Less transfer • Can’t use all applications because of narrowband • Business • Demands for monitoring the train using video streaming

  3. The Goal of this Research • To provide the communication environment faster than 1 Gbps to High-speed train • There are three requirements for the goal • Communication Speed • The current wireless LAN technologies (WiFi and WiMAX) cannot satisfy this requirement • Session Continuity • Fast Handover Mechanism

  4. Communication Speed over 1Gbps • Infrared Comm. Device (IR-CD) • has been developed by Prof. Shinichiro Haruyama* and Railway Technical Research Institute * Graduate School of System Design and Management, Keio University Front view Rear view Infrared laser Serial Interface Beacon Ethernet Interface SPEC Speed : 1.25 Gbps Range : 360m Feature : Directional Power cable Power Switch Receive Level

  5. Session Continuity • Network Mobility (NEMO) Basic Support [RFC3936] • The network mobility protocol in IPv6 • Mobile Router (MR) • executes handovers and provides mobile node with mobility-transparent connectivity • Home Agent (HA) • manages the binding of Home Address (HoA) and Care-of Address (CoA) Home network (4) Communication HoA Correspondent Node MR HA Mobile network (3) Foreign Network CoA (2) Mobile network (1) Movement MR (2) Register CoA and MNP with HA (3) IPv6–in IPv6 tunnel

  6. Fast Handover Mechanism • Conventional Handover Procedure • takes more than 1 sec 1. Waiting for receiving Router Advertisement (RA) message 2. The Duplicate Address Detection (DAD) procedure HA new AR (4) RA (6)BU (7)BA (3) wait for RA (5) DAD NetworkLayer Mobile Node Total disruption time (more than 1 sec) LinkLayer (1) comm. qualitygetting worse (2) L2 handover BU : Binding Update message BA : Binding Acknowledgement message

  7. L3-Driven Fast Handover • L3-Driven Fast Handover [RFC5184] • Developed in our laboratory • Using cross-layer collaboration • We defined link layer primitives HA new AR (8)BU (9)BA (4) pre-DAD NetworkLayer (2) L2-LinkStatus Changed (3) L2-PoAList (7) L2-LinkUp (5) L2-LinkConnect Mobile Node Total disruption time (10-15 ms) LinkLayer (1) comm. qualitygetting worse (6) L2 handover

  8. Proposal:Fast Handover Mechanism For the IR-CD • Eliminating DAD processing Time • DAD process • In case of WiFi • It is possible to predict handovers by Receive Signal Strength Indicator • Execute DAD before handovers • In case of IR-CD • It is impossible to predict handovers • Cannot execute DAD before handover • Single administration organization • A Railway company • Assign each mobile router a unique interface identifier • Therefore, the proposed mechanism disables DAD processing

  9. Proposal:Fast Handover Mechanism For the IR-CD • Eliminating Waiting Time to Detect Link Layer Handover • In case of IR-CD • MR and IR-CD are connected by Ethernet cable • Link state between MR and IR-CD is always LinkUp state • IR-CD is regarded as a repeater • Connect IR-CD to MR with Data cable and Control cable • Control cable can notify MR of the infrared link state(LinkUp/LinkDown) Infrared Comm. Device on the train Infrared Comm. Device on the ground Data cable(1 Gbps) Infrared Laser LinkUp/LinkDown Control cable Train

  10. Proposal:Fast Handover Mechanism For the IR-CD • The Proposed Procedure HA new AR (5) RS (6) RA (7) BU (8) BA NetworkLayer (2) L2-Linkdown (4) L2-Linkup Mobile Router Total disruption time LinkLayer (1) Linkdown frame (3) Linkup frame Infrared communication device

  11. Implementation • Environment • OS : NetBSD 4.99 • SHISA • An implementation of Mobile IPv6 and NEMO BS on NetBSD • fhod (fast handover daemon) on NetBSD • Daemon to achieve fast handover Binding Update Database mrd fhod nemonetd userland Routing Socket kernel Mobility Socket Destination Optionsheader module Binding Management module Neighbor Discovery module Address Management module Routing table Management module Binding Update Database Routing table Our implementation Module diagram of our implementation based on SHISA Tunneling module Forwarding module

  12. Message Flow • Message Flow in L3 Handover Train MR HA IR-CD fhod mrd nemonetd Prev. AR new AR Link disconnected (1)Linkdown Link connected (3)Linkup (5) RS (6) RA (7) BU (8) BA Tunnel estab. tunnel

  13. Evaluation – Handover Time - • Test network • Emulate the train environment train ground router IR-CD MR AR HA HA CN Linkup 0.003msec AR-2 AR-1 RS 1.7msec RA scenario 0.3msec Wireless Environment Emulator BU 4.0msec MR BA Data cable Control cable CN: Correspondent Node LFN: Local Fixed Node Details of Handover Time LFN

  14. Evaluation – Packet Loss Ratio - • configuration • 10 IR-CDs are connected to a single AR • a handover occurs per 5 seconds • A train runs at 300km/h and IR-CD is installed every 420m • a L3 Handover occurs in 10 handovers • packet loss never occurs on the infrared link • L2 handover time • 10ms, 50ms, 100ms • RTT between MR and HA • 0 – 30 ms • UDP packet were sent form CN toMR at 1 Mbps Even in the worst case, The average packet loss ratio is about 2%.

  15. Conclusion • The goal of this research • To provide the mobile network in high-speed train withhigh-speed connectivity (more than 1 Gbps) • We proposed a fast handover mechanism • Using cross-layer collaboration for mobile network installed in High-speed train • Defined the Linkup control frame • MR can immediately start handover procedure • The measurements show that • handover time is approximately 6.0ms + L2 handover time • packet loss ratio is approximately 2 % in the worst case.

  16. Thank you for your attention.

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