Discussion – How Many APs to Cover Month Year doc.: IEEE 802.11-yy/xxxxr0 May 2011 Discussion – How Many APs to Cover Date: 2011-05-10 Authors: Dwight Smith Motorola Mobility 5300 Westport Parkway Fort Worth, TX 76177 +1 682-514-4861 dwight.smith@motorola.com Dwight Smith, Motorola Mobility John Doe, Some Company

Month Year doc.: IEEE 802.11-yy/xxxxr0 May 2011 Abstract When looking at the ‘Initial Link Setup’ for a STA we have been consistent considering the link established upon entry of an ESS. Typically, it would involve the initial AP the STA finds in the ESS, but the question for consideration is – should TGai consider the possibility of the Link Setup involving more than one AP? This presentation addresses some of the issues to help consider the factors involved. Dwight Smith, Motorola Mobility John Doe, Some Company

May 2011 Factors to Consider While the use cases imply that STAs notice an AP at first possible moment, in fact, they would ‘see’ the AP after they scan which is at some arbitrary period later. While some devices claim to try to be ‘always connected’ they do not do constant scanning when unassociated . The scan interval for devices are implementation and battery state dependent. When a Link Setup sequence is started at an AP and does not complete there – is it better to start over at the next AP, or is it feasible to continue the operation at the next AP? Is it viable to expect the APs in an ESS to be able to hand-off/pick up partially complete Link Setup – what information would be needed to carry such operations between APs in the ESS. Dwight Smith, Motorola Mobility

May 2011 Example Timeline Caveat – this is not real sample but a representation to describe case This is intended to show the trend for large number of STAs impacting the AP Timing represents devices staying in coverage and completing Link Setup where in real life a portion would actually be moving out of coverage Dwight Smith, Motorola Mobility

Month Year doc.: IEEE 802.11-yy/xxxxr0 May 2011 Discussion and Review Should TGai propose support elements for Link Setup operations that involve more than one AP? Do the existing use cases capture the key factors? Have we considered operational approach of related operations? 11r – Prep for BSS transition in setup Others? Dwight Smith, Motorola Mobility John Doe, Some Company