1. doc.: IEEE 802.11-11/1015r1 Submission 07-2011 Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUSSlide 1 Network Selection Optimization Date: 2011-07-20 Authors:

2. doc.: IEEE 802.11-11/1015r1 Submission 07-2011 Slide 2 Abstract An optimized network discovery and selection is presented. Today, a STA requiring network information has to conduct AP discovery (scanning) and network discovery. The overhead occurring in environments with a large number of APs or with several STAs simultaneously starting AP/network discovery can be reducing by combing both phases as presented herein. Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS

3. doc.: IEEE 802.11-11/1015r1 Submission 07-2011 ANQP (Table 8-176 infoID req) ANQP Resp (ANQP IE) SSID1SSID2 ANQP (Table 8-176 infoID req) ANQP Resp (ANQP IE) SSID3 ANQP (Table 8-176 infoID req) ANQP Resp (ANQP IE) What we have today: one STA several APs PROBE.request (Broadcast) PROBE.response AP discovery (alternative: wait for all beacons) Network discovery - ANQP is unicast -Each SSID is queried until a suitable network is found. -This frame exchange is conducted for every STA that wants to conduct a link set-up Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS

4. doc.: IEEE 802.11-11/1015r1 Submission What we have today: cost of AP discovery & network discovery Let –AP – number of APs in communication range –STA – number of STAs “simultaneously” requesting link set-up (simultaneously = within a given, short timeframe) Then –AP-Discovery requires: STA * (1 + AP) message exchanges –Network Discovery requires in between 1 st AP is selected: STA * 2 and last AP is selected: STA * 2 * AP message exchanges 07-2011 Slide 4 1 Probe.req + 1 probe.res for each APDone for each STA 1 ANQP.req+ 1 1 ANQP.res Done for every AP Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS

5. doc.: IEEE 802.11-11/1015r1 Submission How ANQP is done today 07-2011 Slide 5 ANQP (Table 8-176 infoID req – ask for property # 1) ANQP Resp (ANQP IE -- all properties including property #1 are returned) ANQP (Table 8-176 infoID req – ask for property # 2) ANQP Resp (ANQP IE -- all properties including property #2 are returned) Pro: low processing at AP (parsing / evaluation done at STA)  fast Con: Large overhead, STA #2 could have obtained the answer from the contents of the 1st reply Same information contained in the response. Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS

6. doc.: IEEE 802.11-11/1015r1 Submission Optimized approach 07-2011 Slide 6 ANQP (Table 8-176 infoID req – ask for property #1)  broadcast ANQP Resp (ANQP IE – reply with all properties)  broadcast Same AP Discovery as we have today  each STA issues a probe.req. STA 1 gets answer it requested STA 2 parses answers as well  high properbility that STA 2 does not need to request additional information Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS

7. doc.: IEEE 802.11-11/1015r1 Submission How much can we save in Network Discovery? Remember what we have today: 1 st AP is selected: STA * 2 and last AP is selected: STA * 2 * AP With improved network discovery: –Best case (all STAs can retrieve required properties from 1 st response first AP is selected: 1 + AP –Worst case (no STA can retrieve required properties from 1 st response last AP is selected: STA * ( 1 + AP ) Gains: Worst case performance of improved scheme has same performance as expected mean of message exchange of today’s scheme But we can do even better: Since responses are broadcast as well, why not combine network discovery and AP discovery phase ? 07-2011 Slide 7 Done for each STA1 ANQP.req+ 1 1 ANQP.res Done for every AP ANQP.req.ANQP.res from every AP Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS

8. doc.: IEEE 802.11-11/1015r1 Submission 07-2011 Beacon (interworking capability) ANQP (Table 8-176 infoID req)  broadcast ANQP Resp (ANQP IE) SSID1SSID2 ANQP Resp (ANQP IE) Network Selection (SSID2) Association Request Proposed optimized network selection procedure SSID3 - ANQP to be sent to the broadcast address -AP answers if it can satisfy the condition in the request -ANQP responses are sent unicast Saves (n-1)*RTT during the network selection procedure, n = nr of SSIDs queried, and the passive scanning period Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS

9. doc.: IEEE 802.11-11/1015r1 Submission Optimized approach II: combine with (active) network discovera 07-2011 Slide 9 ANQP (Table 8-176 infoID req – ask for property #1)  broadcast ANQP Resp (ANQP IE – reply with all properties)  broadcast Same AP Discovery as we have today  each STA issues a probe.req. X X X X X Include information from probing in “new” message Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS

10. doc.: IEEE 802.11-11/1015r1 Submission Further improvement: AP-Discovery requires: STA * (1 + AP) New, improved Network Discovery requires in between –Best case (all STAs can retrieve required properties from 1 st response last AP is selected: 1 + AP –Worst case (no STA can retrieve required properties from 1 st response last AP is selected: STA * ( 1 + AP ) 07-2011 Slide 10 1 Probe.req + 1 probe.res for each APDone for each STA X X X X X ANQP.req.ANQP.res from every AP Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS

11. doc.: IEEE 802.11-11/1015r1 Submission Should this approach always be used? Obviously not –E.g., in an enterprise environment, STAs might not need to do any network selection at all –  use „old“ scheme Employ novel / combined scheme as an alternative scheme to conduct a link set-up –STAs can decide / be told (via MIB variable ?) which scheme to use 07-2011 Slide 11Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS

12. doc.: IEEE 802.11-11/1015r1 Submission Straw Poll Is there interest in the group to receive further presentations and draft amending text based on the ideas presented afore? Yes: No: 07-2011 Slide 12Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS