MCCAOP Advertisement discussion

1. MCCAOP Advertisement discussion Authors: Date: 2011-01-19 Dee Denteneer, Philips

2. Abstract This presentation provides a perspective on the MCCA comments received during the recirculation and specifically zooms in on the MCCAOP advertisement mechanism as in the Draft 8.0 and provides a tentative route towards a solution. Dee Denteneer, Philips

3. MCCA comments: 40 • More or less editorial: 23 (will do my best) • Advertisements: 17 (this presentation) • Concerning the Advertisements • Terminology • Completeness • When are advertisement elements part of the ‘same’ advertisement • Teardown of reservations • ‘Partial ‘ advertisements Overview Dee Denteneer, Philips

4. Current structure Dee Denteneer, Philips

5. Add an Advertisements Set Sequence Number • As per 814r1 • Groups together a number of Advertisement elements • Add an MCCAOP Advertisements Overview element • Contains a Advertisements Set Sequence Number • Contains a bitmap, indicating which Advertisement elements are available in the current Advertisment Set Suggested modification Dee Denteneer, Philips

6. Proposed data structure, changes to current Dee Denteneer, Philips

7. Proposed structure, Advertisements Overview element The Advertisements Elements n Active indicates which of the advertised Advertisement elements with the same set sequence number are part of the current Advertisement Set Dee Denteneer, Philips

8. The set of tracked MCCAOP reservations is distributed over Advertisement elements • Each Advertisement element has a 4 bit identifier and contains reports that contain the reservations • The advertisement set sequence number groups the Advertisements elements • The overview element is regularly transmitted and acts as a key to validate completeness • Given a Advertisement Set Sequence Number, limited changes are allowed to the Advertisement Set • An element can be retrieved, indicated in the Overview element • An element can be added, indicated in the Overview element • However, an element cannot be changed • Once a bit for an advertisement element has been set to 1 and afterwards set to 0, it may never been set to 1 again with the same Advertisement Set Sequence Number Functionality Dee Denteneer, Philips

9. A complete overhaul of the distribution of reservations over the Advertisements elements is possible by increasing the Advertisement Set Sequence Number. This invalidates all Advertisement elements with an older Sequence number • However, given an advertisement element with the right sequence number, and that is still indicated in the bitmap as active, a mesh STA knows this Advertisement element is still ok • Enhanced Advertisements Request possible • Request the Overview • Request a specific set of elements • Request the delta given your own bitmap Functionality Dee Denteneer, Philips

10. We now discuss how this scheme meets the objections raised in the comments Reflection Dee Denteneer, Philips

11. advertisement set: Set of all Reservations to be advertised equals All tracked reservation • Distributed over multiple Advertisement elements • Use advertisement set sequence number to group these • Index each Advertisement Element • An advertisement equals the transmission of all (complete), active Advertisement elements and the advertisement overview element • Advertisement frames may carry zero or more Advertisement elements and one or zero overview element Terminology (cf. 11-10/814r1) Dee Denteneer, Philips

12. The Advertisement Overview element is a key to the current Advertisement Set of a mesh STA A mesh STA can easily check the completeness of its picture of the Advertisement Set of a neighbor by using the Advertisements Overview element A mesh STA can simply request a delta to complete its picture of the Advertisement Set of a neighbor Completeness Dee Denteneer, Philips

13. A mesh STA can easily teardown the reservations in a Advertisement element by setting the corresponding bit in the bitmap to zero • To teardown individual reservations you could delete one Advertisement element and advertise a new Advertisement element • Note: Once an advertised reservation needs to be advertised, there are two choices: • Increase Sequence number, retransmit everything • If a “bit” in the bitmap has not been used before, the element that contains the changed reservation can be placed in a new “bit” and the old bit is invalidated (aka set to 0). Teardown Dee Denteneer, Philips

14. Advertisements are by nature partial, so this notion can be deleted New reservations can simply be advertised by transmitting a new Advertisement element and setting the corresponding bit to 1 in the Advertisements Overview element Partial Advertisements Dee Denteneer, Philips

15. Is it clever to include several “reports” in one Advertisement element, or rather: have the elements typed (i.e. this gives an extra hierarchical level in the data structure) Even further, do we need elements to group reservations, or do we rather wotk with the individual reservations Possible further changes Dee Denteneer, Philips

16. Advertisement element, possible simplifcation Note: dispense of the “Report level”, give a type to the Advertisement element Allows for 64 Advertisement elements and needs a larger bitmap in the overview element Note: could also index and type the reservations themselves Dee Denteneer, Philips

17. References • 11-10/814r1 „MCCAOP Advertisements“ • contains normative text implementing these ideas • IEEE 802.11s D8.0 Dee Denteneer, Philips