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Change in Scanning Procedure

Change in Scanning Procedure. Date: 2012-01- 19. Authors:. Abstract. The presentation provides suggested input to the TGai Spec Framework addressing the following functionality: “Stopping an ongoing scanning process”

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Change in Scanning Procedure

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  1. Change in Scanning Procedure Date:2012-01-19 Authors: Marc Emmelmann, Fraunhofer FOKUS

  2. Abstract The presentation provides suggested input to the TGai Spec Framework addressing the following functionality: “Stopping an ongoing scanning process” The presentation includes anticipated savings in the duration of the AP discovery phase resulting from this approach and summarizes the issues with the current 802.11 spec that need to be addressed. Marc Emmelmann, Fraunhofer FOKUS

  3. Acknowledgements • Please check the long reference list. The “expected performance gains / analysis” was compiled from those submissions Marc Emmelmann, Fraunhofer FOKUS

  4. Outline • Status Quo & Potential Approaches to improve Performance of AP Discovery • Anticipated Performance Improvements of the proposed approach • Problem statement / Limitations of current 802.11 spec • Suggested input for TGai Spec Framework Marc Emmelmann, Fraunhofer FOKUS

  5. Access Point Discovery: Today • Potentials for improvement: • Return from scanning procedure after having found the 1st AP • Use “external” knowledge on which channels to scan • What about 5GHz operation—really only passive scanning or are there potential alternatives for faster AP discovery? Expected Meanof time spent inscanning for No Assumptions(scan all channels),find all APs • Note: • Qi & Walker (11-10/853r1) provide worst case approximations of up to 3400ms. • 11-10/922r2 contains details how the assumptions behind the expected mean calculation for the values presented herein 2.4 GHz 5 GHz Passive scanning 1100 ms 2300 ms Active scanning 102 ms n/a • Source: 11-10/922r2 Marc Emmelmann, Fraunhofer FOKUS

  6. AP Discovery: Return after 1st AP is found • Potential gain returning after 1st AP found • Problem with current 802.11 spec • Passive scanning • Theoretically, this is possible: “shall listen to each channel scanned for no longer than a maximum duration defined by the MaxChannelTime“ [11REVmb-D4, Cls 11.1.3.1] • BUT: currently, there is not option to the MLME-SCAN.request primitive forcing this behavior. • Active scanning: • Not possible right now: “…. [scan until] ProbeTimer reaches MaxChannelTime, process all received probe responses“ [11REVmb-D4, Cls 11.1.3.2.2] No Assumptions(scan all channels),stop after 1stAPsis found Expected Meanof time spent inscanning for No Assumptions(scan all channels),find all APs 2.4 GHz 5 GHz 2.4 GHz 5 GHz Passive scanning 1100 ms 2300 ms 550 ms 1150 ms Active scanning 22 ms 102 ms n/a n/a • Source: 11-10/922r2 Amendment required Marc Emmelmann, Fraunhofer FOKUS

  7. High Level Input to TGai Spec Framework • Problem: • 802.11 does not specify a controlled way to request the scanning process to stop after an appropriate(*) AP has been found. • (*) may be the 1st AP found or an AP fulfilling certain characteristics • Requirement (for TGai Spec Framework): • TGaishall provide a mechanism allowing to stop an ongoing scanning process • Straw Poll: • Are you in favor to add the following statement to the TGai Spec Framework: “TGai shall provide a mechanism to allow to stop an ongoing scanning process” ? • Y/N/A: Marc Emmelmann, Fraunhofer FOKUS

  8. References • 11-10/853r1: Some concerns about FIA (Emily Qi and Jesse Walker, Intel) • 11-10/922r2: Achievable gains in AP discovery (Marc Emmelmann, Fraunhofer FOKUS) • 11-10/965r1: Potential performance improvement with fast initial link set-up (Marc Emmelmann, Fraunhofer FOKUS & Root Inc.) • 11-10/988r1: Protocol comparison (Hitoshi Morioka, Root Inc.) • 11-10/1008r2: Parallel processing for upper layer (Hiroki Nakano, TNT Inc.) • 11-10/980r0: FIA Security Analysis Bob Moskowitz • 11-10/832r0: Comments to PAR & 5C (M. Emmelmann, Fraunhofer FOKUS & Root Inc.) • 11-10/1106: Transition from FIA to FILS (M. Emmelmann, Fraunhofer FOKUS) • 11-11/1015: Optimized network selection (Gabor Bajko, Nokia, NecatiCanpolat, Intel) • H. Mano et al: FILS Proof-of-Concept Demonstration – Documentation slide set, Okinawa, Japan, Sep 2011 • 11-11/1237r1: TGai Key Technical Ideas (M. Emmelmann) Marc Emmelmann, Fraunhofer FOKUS

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