TGn Simulation Methodology Ad Hoc Overview Jeff Gilbert Atheros Communications J.Gilbert, Atheros Communications

Month 2003 doc.: IEEE 802.11-03/xxxr0 History Simulations methodology ad hoc has been formed based on the belief by the majority of the TGn body that we need a unified way of modeling the PHY error rate in MAC / System simulations Issue has been raised: J.Gilbert (Atheros) - 11-03-0888 – Albuquerque Large consensus in 1/6/04 FRCC telecon. of need H.Bonneville and B.Jechoux (Mitsubishi) 11-04-0120 Vancouver – 1/15/04 TGn straw polls and votes J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications

Month 2003 doc.: IEEE 802.11-03/xxxr0 Charter Simulation Methodology Ad hoc was discussed and approved in the TGn session on 1/15/04 and announced at the 1/16/04 closing plenary Bi-weekly conference calls to be held Ad Hoc chartered through March Plenary (w/ extension by TGn vote if nec.) to define a PHY-MAC interface to be used in MAC simulations generating results reported in the CC matrix Following the sub-committee's completion there will be a TGn vote to determine whether the methodology will be mandatory or optional J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications

PHY Abstraction problem Month 2003 doc.: IEEE 802.11-03/xxxr0 PHY Abstraction problem PHY / MAC interface can dramatically impact overall results: Time varying channel creates time varying PER Affects overall delay, jitter, and goodput Challenges Properly model PHY characteristics in MAC sims Keep flexibility to readily adapt to different proposals’ PHYs Keep simulation effort reasonable J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications

Goals Goals of a common phy / MAC interface: Month 2003 doc.: IEEE 802.11-03/xxxr0 Goals Goals of a common phy / MAC interface: Allow fair comparison of MAC / system results Facilitate verification / cross-checking of results Intermediate results to simplify process Possible other goals to be discussed: Ability to merge MAC and PHY from different proposers Ability to simulate MAC-only modifications with known PHY J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications

Risks of not specifying Abstraction Month 2003 doc.: IEEE 802.11-03/xxxr0 Risks of not specifying Abstraction Without common PHY/MAC interface, results could depend more on simulation methodology than proposal Possible interpretations: Idealized PHY Distance -> fixed PER (based on theoretical values) Distance -> mean SNR (w, w/o interference) -> PER Distance -> fading SNR (w, w/o interference) -> PER Distance -> fading SNR -> capacity formula -> PER Fully accurate PHY model w/rate adaptation -> PER lookup Approximate PHY based on SNR profile in MAC simulation Full PHY simulation per packet in MAC simulation Standardizing the abstraction could save significant time during the proposal evaluation selection process J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications

Some PHY Abstraction-Related Work Month 2003 doc.: IEEE 802.11-03/xxxr0 Some PHY Abstraction-Related Work Black-box PHY methods Use full accuracy of PHY sims w/ rate adapt encapsulated in tables Tight coupling of channel & PHY models, looser coupling w/ MAC Example from Mitsubishi /Atheros (11-04/0xxx) PHY integrated into MAC methods Parametric version of PHY incorporated in system simulations Looser coupling of channel & PHY models, tighter coupling w/ MAC Example from Intel (11-03/0863) “Channel Capacity to determine PERs” method Markov model for channel capacity mapped to PERs Channel capacity links Markov channel model and per-rate PERs Example from from ST Microelectronics (11-04/0064) Challenges: Accurately model channel variation, MAC interactions, arbitrary PHYs J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications

Goals of the Ad Hoc Committee Month 2003 doc.: IEEE 802.11-03/xxxr0 Goals of the Ad Hoc Committee Determine a methodology that the TGn body will choose to adopt to allow fair comparisons If we cannot arrive at a single methodology, refine 2-3 to be selected from at the March 2004 session All members of ad hoc should provide positive feedback to improve the various approaches and focus on consensus J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications

Process of the Ad Hoc Committee Month 2003 doc.: IEEE 802.11-03/xxxr0 Process of the Ad Hoc Committee It is critical that we move quickly in order to have conclusions to present at the March 2004 session There will be 3 calls prior to the March 2004 session: Feb 05, 2004 08:00 Pacific Time Feb 19, 2004 00:00 Pacific Time Mar 04, 2004 16:00 Pacific Time Proposed Agenda: During the 1st call, the goal of the group and overview of different approaches will be discussed During the 2nd call, specific proposed methodologies (posted on server w/ email to reflector by Feb 16) will be discussed During the 3rd call, proposal(s) to be presented to the TGn body (posted w/email by Mar 1) will be selected and refined J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications