doc.: IEEE /1015r1 Submission Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUSSlide 1 Network Selection Optimization Date: Authors:

doc.: IEEE /1015r1 Submission 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

doc.: IEEE /1015r1 Submission ANQP (Table infoID req) ANQP Resp (ANQP IE) SSID1SSID2 ANQP (Table infoID req) ANQP Resp (ANQP IE) SSID3 ANQP (Table 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

doc.: IEEE /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 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

doc.: IEEE /1015r1 Submission How ANQP is done today Slide 5 ANQP (Table infoID req – ask for property # 1) ANQP Resp (ANQP IE -- all properties including property #1 are returned) ANQP (Table 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

doc.: IEEE /1015r1 Submission Optimized approach Slide 6 ANQP (Table 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

doc.: IEEE /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 ? 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

doc.: IEEE /1015r1 Submission Beacon (interworking capability) ANQP (Table 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

doc.: IEEE /1015r1 Submission Optimized approach II: combine with (active) network discovera Slide 9 ANQP (Table 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

doc.: IEEE /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 ) 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

doc.: IEEE /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 Slide 11Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS

doc.: IEEE /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: Slide 12Gabor Bajko, Nokia, Canpolat, Intel, Emmelmann, FOKUS