November 2007 doc IEEE 802 11 072853 r

November 2007 doc. : IEEE 802. 11 -07/2853 r 0 802. 11 s functional interdependences Date: 2007 -11 -13 Authors: Submission 1 Jarkko Kneckt, Nokia

November 2007 doc. : IEEE 802. 11 -07/2853 r 0 Abstract This presentation provides a view to interdependencies of the following basic 802. 11 s functionality – synchronization – scheduled access – power save This is intended to be used in decision-making on synchronization as both the scheduled access and the power save rely on its services – Can we have a solid basis for scheduled access and power save from the synchronization? Submission 2 Jarkko Kneckt, Nokia

November 2007 doc. : IEEE 802. 11 -07/2853 r 0 The big picture (revisited) • 802. 11 s mesh network should be built on the same components independently from the reason to form and run the network – Don’t want to end up with fragmented standard and markets with separate feature sets and vendor specific extensions breaking interoperability • Consequently all the 802. 11 s compliant devices should be capable of operating as MPs • MP should be able to form a link to any other MP • At the very minimum we would like to see some level of synchronization required from all the MPs – Facilitates development of common set of scheduled access and power save functionality Submission 3 Jarkko Kneckt, Nokia

November 2007 doc. : IEEE 802. 11 -07/2853 r 0 Definitions • Synchronization – Defines whether the peer MPs need to have common conception of time • In the loosest form two peer MPs have no time reference they can use to tell each other when something will happen (No sync) • In the tightest form all the MPs in the mesh network share common conception of time and can tell each other when something will happen (Mesh-wide sync) • Scheduled access – At least two MPs share a common view on time when frames will be exchanged in peer links • Only the MPs in the link share the view (Link specific) • All the MPs share the view and respect the allocations (MDA) • Power save – Protocols and functionality that allow for an MP entering into doze state in controlled manner • The MPs in the link share the view on each other’s power state transitions without beacon support (Link specific) • Power save state transitions support provided in beacons (Beacon support) • Power save state transitions tightly coupled with the access schedule (Scheduled) Submission 4 Jarkko Kneckt, Nokia

November 2007 doc. : IEEE 802. 11 -07/2853 r 0 Interdependency tree Scheduled access Power save • Both the scheduled access and the power save build upon the synchronization mechanisms – Scheduled access requires a common conception of time shared by a) two peer MPs, b) a group of MPs relatively close to each other, c) all the MPs in the network – Power save can benefit from the same synchronization mechanisms and also requires some level of common conception of time • Power save can also be built upon scheduled access – MP’s power state (awake/doze) can be coupled with the schedule Submission 5 Jarkko Kneckt, Nokia

November 2007 doc. : IEEE 802. 11 -07/2853 r 0 From synchronization to scheduled access Synchronization No sync Peer offset Mesh-wide Scheduled access Link specific • • Without synchronization there will be no scheduled access Some form of peer offset tracking mechanism allows for link specific schedules – Common time reference needed • • • MDA It doesn’t necessarily need to be TSF/TBTT/beacon based TSF/TBTT is preferred as it exists with the beaconing MDA requires mesh-wide synchronization Submission 6 Jarkko Kneckt, Nokia

November 2007 doc. : IEEE 802. 11 -07/2853 r 0 From synchronization to power save Synchronization No sync Peer offset Mesh-wide Power save Link specific • • Scheduled Without synchronization there will be no power save Some form of peer offset tracking mechanism is enough for all levels of power save – – – • Beacon support Common time reference needed for wakeups unless one of the MPs is always in awake state Beacon based signaling requires peer link offset tracking Scheduled power save just requires common time reference for the peer link, TSF/TBTT is preferred as it exists with the beaconing Power save doesn’t benefit from mesh-wide synchronization Submission 7 Jarkko Kneckt, Nokia

November 2007 doc. : IEEE 802. 11 -07/2853 r 0 The big picture Synchronization No sync Peer offset Mesh-wide Scheduled access Link specific Power save MDA Link specific Beacon support Scheduled • Without synchronization there will be no scheduled access and only a very limited and inefficient link specific power save scheme • Mesh-wide synchronization is needed for MDA, and only for MDA Submission 8 Jarkko Kneckt, Nokia

November 2007 doc. : IEEE 802. 11 -07/2853 r 0 Summary and proposal • Without synchronization there will be no scheduled access and only a very limited and inefficient link specific power save scheme – There will be no common basis for scheduled access or power save either • Could we make peer link offset synchronization mandatory to create the basis for the rest of the functions? Submission 9 Jarkko Kneckt, Nokia