March 2004 doc IEEE 802 11 040170 r

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March 2004 doc. : IEEE 802. 11 -04/0170 r 2 TGn Simulation Methodology Ad

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 TGn Simulation Methodology Ad Hoc Overview Jeff Gilbert Atheros Communications Submission 1 J. Gilbert, Atheros Communications

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 History – Simulations methodology

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 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 Submission 2 J. Gilbert, Atheros Communications

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Charter – Simulation Methodology

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 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 Submission 3 J. Gilbert, Atheros Communications

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 PHY Abstraction problem –

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 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 Submission 4 J. Gilbert, Atheros Communications

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Goals – Goals of

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 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 Submission 5 J. Gilbert, Atheros Communications

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Risks of not specifying

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 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 -> 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 Submission 6 J. Gilbert, Atheros Communications

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Some PHY Abstraction-Related Work

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 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 -04/0172) – 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 ST Microelectronics (11 -04/0064) – Challenges: • Accurately model channel variation, MAC interactions, arbitrary PHYs Submission 7 J. Gilbert, Atheros Communications

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Goals of the Ad

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 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 Submission 8 J. Gilbert, Atheros Communications

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Process of the Ad

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 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 08: 00 Pacific Time • Mar 04, 2004 08: 00 Pacific Time – Proposed Agenda: • During the 1 st call, the goal of the group and overview of different approaches will be discussed • During the 2 nd call, specific proposed methodologies (posted on server w/ email to reflector by Feb 16) will be discussed • During the 3 rd call, proposal(s) to be presented to the TGn body (posted w/email by Mar 1) will be selected and refined Submission 9 J. Gilbert, Atheros Communications

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Methodology Requirements – These

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Methodology Requirements – These requirements were discussed on the first conference call and will be updated as new suggestions come on the calls or emails. – These have not been ranked / approved by the group. The requirements are to accurately model: • • Submission Beamforming gains Bit / packet errors Channel variation and resulting varying PER Interference effects MIMO MAC operation with multiple independent data streams PHY impairments Rate adaptation interactions with the PHY 10 J. Gilbert, Atheros Communications

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Sample TGn Technologies –

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Sample TGn Technologies – By considering the variety technologies to be proposed for TGn, the methodologies can make sure that they can adequately represent performance. – This list was discussed on the first call and will be updated as new suggestions come on the calls or emails. – These have not been ranked / approved by the group: • Adaptive bit-loading – Closed loop – Many more coding rates • Beamforming / nulling • LDPC / other coding methods • MIMO / Multiple data streams Submission 11 J. Gilbert, Atheros Communications

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Simulation Tools Used –

March 2004 doc. : IEEE 802. 11 -04/0170 r 2 Simulation Tools Used – This page lists the simulation tools used by members. This is informative only and not meant to imply that a particular tool or tools are mandated or recommended by the ad hoc. – This list was discussed on the first conference call and will be updated as new information comes on the calls or emails: • Opnet + C-models (1) • MLDesigner (1) • NS (2) Submission 12 J. Gilbert, Atheros Communications