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TGe ‘Fast track’ proposed Draft Normative Text Changes

TGe ‘Fast track’ proposed Draft Normative Text Changes.

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TGe ‘Fast track’ proposed Draft Normative Text Changes

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  1. TGe ‘Fast track’ proposed Draft Normative Text Changes Sai Shankar, Javier del Prado, Amjad Soomro, Kiran Challapali, Atul Garg, Benno Ritter, PhilipsMathew Sherman, AT&TPartho Mishra, Frank Howley, Rolf De Vegt, AirgoMathew Shoemake,TIMorihiko Hayashi, SonyIsaac Lim Wei Lih, Matsushita

  2. Outline • Overview of the rate-based proposal • Description of proposed changes • Comparison with Time-based proposal • Conclusion

  3. Application 1 Rate-based Application Interface MAC PHY Air Interface 2 3 Negotiation: Rate-based Announce Service Schedule Rate-Based Proposal • Application (in WSTA) requests “Rate,” across the application interface • TSPEC in the form of min/mean/max rate, delay.. • WSTA requests HC for Rate • HC negotiates and admits stream, announces schedule for the WSTA • Schedule re-announced, if needed • No renegotiations 1 2 3

  4. Changes to the Text • Suggested text for TSPEC • Suggested text for Announced Schedule • Definition of normative behavior of scheduler added

  5. TSPEC element • Application (in WSTA) requests “Rate,” across the application interface • WSTA requests service from HC for a TS using the above format

  6. TSPEC element (Contd.) • Suggested text for TSPEC that clarifies the definition of parameters • All parameters do not need to be specified by an application • A zero value indicates parameter is unspecified • Added “Peak data rate” field to TSPEC • for clarification of maximum burst size • TSPEC is encoded using TLV

  7. Schedule Element • HC negotiates and admits stream, announces schedule • The scheduling information is sent using a Schedule QoS Action frame • Announcing the schedule addresses power management solidly • without putting undue restriction on the scheduler • without requiring changes to the API

  8. Scheduler Behavior • Added section on “Schedule management by the HC” • Defined normative behavior for the scheduler • in terms of bounds • Defined the following • Maximum Inter TXOP Interval • Minimum Inter TXOP Interval • Minimum TXOP Duration • TXOP duration between successive TXOP allocations

  9. Protocol Comparison Time-based Proposal Rate-based Proposal Application Application 1 1 Queue FlowTime-based Rate-based Application Interface MAC MAC PHY PHY Air Interface 2 3 2 3 Negotiation:Time-based Negotiation: Rate-based Announce Service Schedule

  10. Time-based Proposal Application (in WSTA) requests “Air time,” across the application interface Air time in form of TXOP duration and its frequency WSTA requests HC for time HC negotiates and grants TXOPs If channel conditions change (or new stream admitted), HC has to renegotiate with WSTA Rate-based Proposal Application (in WSTA) requests “Rate,” across the application interface Rate in the form of min rate, max rate and delay WSTA requests HC for Rate HC negotiates and admits stream, announces schedule HC has enough information if channel conditions change, no renegotiations Comparison (Contd.) 1 1 2 2 3 3

  11. Application Needs • Throughput in a Wireless channel can vary significantly • Due to multi-path, interference, etc. • Application needs continuity • Yet, provisioning for the worst case is very inefficient • Application may prefer to have rate reduced (say by 20%) rather than be bumped out • Therefore, support for VBR is essential from an application point of view • CBR: special case of VBR • Rate-based approach allows VBR applications • An efficient (high-load) solution for time varying channel

  12. Benefits of Rate-based approach • Applications using Rate parameters “natural” across Application Interface • An efficient (high-load) solution for time varying channel • Rate-based approach supports VBR (VBR superset of CBR) • Rate-based approach the solution for high-load cases • Complements E-DCF that works well for low-load cases • Retains HC flexibility • Complexity • Rate-based does not have the complexity due to renegotiations • Wireless link changes constantly, VBR ... • Conversion from rate-based to a schedule can be simple • WSTA can be thin-clients (several WSTAs per AP) • Rate-based approach supports power management • Schedule is available to WSTA to go to sleep

  13. Conclusions • TSPEC negotiation per TS • Per stream QoS requirements can be met • However, aggregation possible • Schedule Announcement • Power Management • Early local schedule determination at WSTA • No undue restrictions on scheduling • VBR is naturally addressed

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