PAR and 5C: C omments and some draft text based on 802.11n

1. PAR and 5C:Comments and some draft text based on 802.11n Date:2013-09-15 Authors:

2. Sean Coffey, DZ Liu (Realtek) SG Main Task From “HEW SG Progress Review”, Osama Aboul-Magd, doc. 802.11-13/1100r0, Sep 2013 • The normal function of a SG is to draft a complete PAR and five criteria (see rules5) and to gain approval for them from the 802.11 WG – (11-13/0001r2). • Agree on a project scope. • Demonstrate feasibility (technologies exist to achieve the scope) – 5C • Not too many submissions addressing what the problem we are trying to solve is. • Need to be more specific on the problem space. • Need to solicit more submissions that assist in drafting the PAR. • How do we see the work in HEW progressing toward a TG? It’s useful to compare with the development of 802.11n

3. The 802.11n PAR & 5C • Why 11n in particular? • 11ac’s development was complicated by mixture with 11ad: was able to bypass some of the normal PAR & 5C development • Of course 11ac is still relevant. But it has been cited several times. • 11n was the first (mostly-) PHY amendment that moved away from a pure data rate target • Required similar development of new principles (and group consensus thereon) • 11n’s background • Driven by already-existing proprietary extensions: • MIMO (later “True MIMO”)—Airgo Networks • Wider channels (“Super 108”)—Atheros • Other: • Beamforming—Atheros • Protocol improvements (“Fast packets”, up to 150 Mbps from 54 Mbps PHY, etc.) Sean Coffey, DZ Liu (Realtek)

4. Implications for 11n PAR & 5C • Several proposals were made to narrow the scope to preclude some approaches • Confine 11n to PHY-only changes • On the grounds that MAC changes would be too far-reaching / hard to manage; new MAC should mean new Working Group; etc. • Prohibit wider channels • On the grounds that these were not permitted in Europe; didn’t increase overall system capacity; etc. • Prohibit closed-loop modes • On the grounds that these were much more complicated in practice than in theory; didn’t fit well with 802.11’s history and success as an open-loop standard; etc. • Extensive series of straw polls helped establish consensus • Helped by presence of tangible examples Sean Coffey, DZ Liu (Realtek)

5. 11n PAR & 5C wording • “The scope of this project is to define an amendment that shall define standardized modifications to both the 802.11 physical layers (PHY) and the 802.11 Medium Access Control Layer (MAC) so that modes of operation can be enabled that are capable of much higher throughputs, with a maximum throughput of at least 100Mbps, as measured at the MAC data service access point (SAP).” • … “The amendment shall not redefine mechanisms in the baseline that do not pertain to higher throughput.” (explanatory note) • What a mouthful! • But it didn’t matter as it doesn’t appear in the final standard • And was not really used much once TGn started • And the same applies to usage models, simulation scenarios and evaluation methodology • (A) allows MAC changes • (B) doesn’t rule out wider channels • (C) doesn’t rule outclosed-loop modes Sean Coffey, DZ Liu (Realtek)

6. 11n PAR & 5C wording, contd. • The group established consensus based on examples and straw polls rather than the specific wording • Would Tunneled Direct Link Setup / 802.11z have been in scope? • It wasn’t ruled out by the phrase “The amendment shall not redefine mechanisms in the baseline that do not pertain to higher throughput” • How about Fast Initial Authentication? • But it was clear from discussion and straw polls that these and many others would not be in scope • The explanatory note ruled out range extension, lower power, and several other issues that had been proposed Sean Coffey, DZ Liu (Realtek)

7. Some draft text for HEW PAR & 5C • Once a broad consensus is established on the scope, the wording is a relatively easy task • It doesn’t have to be eloquent (as the 11n example shows) • The consensus doesn’t have to be written down • “The scope of this project is to define an amendment that shall define standardized modifications to both the 802.11 physical layers (PHY) and the 802.11 Medium Access Control Layer (MAC) so that modes of operation can be enabled that are capable of much higher relative throughputs, with a maximum relativethroughput increaseof at least 100Mbps 3x, as measured at the MAC data service access point (SAP) in at least three different reference models” • (Break into smaller segments for readability?) • … “The amendment shall not redefine mechanisms in the baseline that do not pertain to higher throughput.” (explanatory note) • …”The amendment shall use (prioritize?) modes that extend modes defined in the 802.11n and 802.11ac amendments” Sean Coffey, DZ Liu (Realtek)

8. Summary and Conclusion • Compared to 11n, HEW lacks the driver of specific shipping technologies • Rough technology consensus should come before PAR • Too difficult to draft and agree a PAR without knowledge of rough outlines of what will be proposed • Sample approach to make constructive progress: • Continue technology presentations • Assemble presentations into broad categories (4-5 at most) • E.g., combine UL MU-MIMO, full duplex technology, and spatially orthogonal/spatial reuse into a single “multiple Tx PHY techniques” category • Start high-level straw-polling on interest in directions • Not specific proposals/presentations • Write PAR & 5C, and simplify evaluation methodology, to fit chosen high-level direction Sean Coffey, DZ Liu (Realtek)