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Supporting real-time services to mobile Internet hosts

Supporting real-time services to mobile Internet hosts. Dissertation thesis proposal Jon-Olov Vatn KTH/IMIT, TSLab. Advisors: Professor Björn Pehrson (Primary advisor) Professor Gerald Q. Maguire Jr. Vision and motivation. Full WLAN coverage within urban areas

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Supporting real-time services to mobile Internet hosts

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  1. Supporting real-time services to mobile Internet hosts Dissertation thesis proposal Jon-Olov Vatn KTH/IMIT, TSLab Advisors: Professor Björn Pehrson (Primary advisor) Professor Gerald Q. Maguire Jr

  2. Vision and motivation • Full WLAN coverage within urban areas • Multiple operators, multiple wireless access networks • Users would like to use WLAN (802.11) for IP based telephony (VoIP) • IPv6 from end-to-end Symbol already has WLAN handsets

  3. Outline • Handover delay and end-to-end delay • Link layer • Network layer • Application layer (VoIP) • Contribution • Time plan • Rough outline of thesis

  4. AR AR AP AP AP AP MN MN MN Handover and end-to-end delay Handover delay • Layer-2 • Layer-2 + Layer-3 • Application layer issues CN HA Internet Tho=f(L2,L3,VoIP)

  5. AR AR AP AP AP AP CN MN Handover and end-to-end delay End-to-end delay • Layer-2 • Layer-3 • Application layer issues • CN also mobile HA Internet Te-t-e=f(L2,L3,VoIP)

  6. Link layer overview • Wireless LAN • IEEE 802.11b • IEEE 802.11a • Upcoming standards (IEEE 802.11g) • Wireless WAN (GPRS) Primarily interested in IEEE 802.11

  7. Handover in 802.11 APold MN APnew • Only one AP at a time • Pre-authentication • WEP or open system • Inter-Access Point Protocol (IAPP) Handover threshold Scanning Auth. Req Auth. Resp. Dissass. Req. Re-ass. Req Re-ass. Resp time

  8. IEEE 802.1X MN AS AP • Additional messages • Access Server (AS) can be located far away • No pre-authentication • IAPP might help • MSc. Degree projects EAP-Request EAP-Req/Id EAP-Resp/Id Radius-Acc-Req Radius-Acc.-Chall EAP-Resp EAP-Req Radius-Acc-Req. Radius-Acc-Accept EAP-Resp time

  9. AR AR AP AP AP AP MN MN Network layer issues • Routing (Mobile IP) • Authentication, Authorization and Accounting (AAA) • Context transfer (Seamoby) CN HA Internet

  10. Routing • Base on earlier work • movement detection • acquire IP address, • redirect data flow • Additional proposals • Hierarchical MIPv6, Bicasting, … • Depend on advanced Layer-2 support • How to evaluate?

  11. AAA related issues • Binding updates • Secure • Public Key Infrastructure • Access control • Network Access Servers • Currently web-based

  12. Transfer of Layer 3 Context IETF Seamoby WG • Candidate Access Router (CAR) discovery • Context information • AAA, QoS, Header compression, PPPoE • Representation • Communication protocol between Geographically Adjacent ARs (GAARs) • Mapping ARs to APs

  13. Voice Over IP • End-to-end delay Te-t-el = Tcodec + Tplayout-buffer + Tnetwork • Adaptive playout buffer algorithms • Using silence periods to adapt • Measure delay and delay variation • Playout point preferably not higher than ~178 milliseconds

  14. Mobile Voice Over IP • How do the playout buffer algorithms handle handover scenarios? • Packet loss and out of order arrival • Step change in delay and delay variation • Handover in the middle of a talk spurt or in silence periods • Other effects? (Non-optimal routing …)

  15. Contribution Describe the full path of events that adds to the handover and end-to-end delay • Quantifying the delay of the components and the overall system • Suggest enhancements (where possible) • Evaluate solutions (critical resources etc.)

  16. Time plan • Starting with layer-2, methods/tools • Supervising MSc degree projects on 802.1X and IAPP, June-Dec 2002 • Layer-3, VoIP and GPRS in parallel • Putting it all together, Dec. 2002 • Disseration Finished, Feb/March 2003 • Disseration Defence, May 2003

  17. Rough outline of thesis • Introduction • Handover delay overview • End-to-end delay for Mobile VoIP • Wireless Systems • IEEE 802.11 • GPRS • IP Mobility • Voice over IP • Putting it all together • Total system design alternatives • Evaluation of alternatives • Conclusions and future work

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