TGn Simulation Methodology Ad Hoc Overview Month 2004 doc.: IEEE 802.11-03/0170r2 TGn Simulation Methodology Ad Hoc Overview Jeff Gilbert Atheros Communications J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications

Month 2004 doc.: IEEE 802.11-03/0170r2 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 2004 doc.: IEEE 802.11-03/0170r2 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 2004 doc.: IEEE 802.11-03/0170r2 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 2004 doc.: IEEE 802.11-03/0170r2 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 2004 doc.: IEEE 802.11-03/0170r2 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 2004 doc.: IEEE 802.11-03/0170r2 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 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 2004 doc.: IEEE 802.11-03/0170r2 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 2004 doc.: IEEE 802.11-03/0170r2 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 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

Methodology Requirements Month 2004 doc.: IEEE 802.11-03/0170r2 Methodology Requirements These requirements were discussed on the first conference call and updated on the calls and/or emails. These have not been ranked / approved by the group. The requirements are to accurately model: 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 Additional metric for comparison is compute resource requirements: CPU cycles and storage J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications

Sample TGn Technologies Month 2004 doc.: IEEE 802.11-03/0170r2 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 J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications

Month 2004 doc.: IEEE 802.11-03/0170r2 Simulation Tools Used This page lists the simulation tools used by members. This is informative only and does not imply that a particular tool or tools are mandated or recommended by the ad hoc. This list was discussed on the 1st conference call and updated from new information on the calls and emails: Opnet + C-models (7): Intel, Mitsubishi, Nortel, NTT, Samsung Electronics, TI, Toshiba MLDesigner (1): Caller not present on call NS (6): Airgo, Atheros, Fujitsu, Marvell, Qualcomm, ST Microelectronics QualNet: UCLA J.Gilbert, Atheros Communications J.Gilbert, Atheros Communications