1. doc.: IEEE 802.11-09/0338r0 Submission March 2009 Chiu Ngo et al. (Samsung Electronics)Slide 1 Enhancement of 802.11 ad-hoc Mode Date: 2009-03-10 Authors:

2. doc.: IEEE 802.11-09/0338r0 Submission March 2009 Chiu Ngo et al. (Samsung Electronics)Slide 2 Abstract This document describes the limitation of the current IEEE 802.11 ad-hoc mode for supporting diverse applications with good user experience and identifies the requirements for enhancement.

3. doc.: IEEE 802.11-09/0338r0 Submission March 2009 Chiu Ngo et al. (Samsung Electronics)Slide 3 Motivation More and more portable / mobile devices are equipped with 802.11 Diverse applications over these low power devices are appealing –Audio/Video streaming (point-to-point, multicasting, broadcasting) –Data transfer, file sharing QoS over 802.11 is challenging in nature, even in infrastructure mode –A/V streaming: video quality expectation is as high as wired streaming –Multiple streams or streaming while data bursting –802.11 nature (interference, lossy medium, saturation) Can the current 802.11 ad hoc mode support good user experience for concurrent diverse applications (A/V streaming, data)?

4. doc.: IEEE 802.11-09/0338r0 Submission March 2009 Chiu Ngo et al. (Samsung Electronics)Slide 4 802.11 ad hoc mode –All members in the IBSS participate in beacon generation (backoff window [0, 2*CWmin]) –Target beacon Tx Time (TBTT): 0, dot11BeaconPeriod TUs, 2 x dot11BeaconPeriod TUs, … –Channel access is contention based only. –11e EDCA for QoS support, but no HC for ad hoc mode.

5. doc.: IEEE 802.11-09/0338r0 Submission March 2009 Chiu Ngo et al. (Samsung Electronics)Slide 5 Key issues Diverse traffic characteristics –Isochronous traffic –Asynchronous traffic –Bursty traffic QoS - video agnostic –EDCA is non-deterministic –QoS is in statistical sense Prioritization doesn’t provide complete solution –Streams in the same access category need to compete –Low priority access category starves Does not adapt well to channel / traffic conditions –Less tolerant to bandwidth saturation and near capacity loading

6. doc.: IEEE 802.11-09/0338r0 Submission March 2009 Chiu Ngo et al. (Samsung Electronics)Slide 6 What are needed? Fully distributed Guaranteed access –Could we borrow some good features from reservation-based TDMA type of channel access? –For example … Flexible for supporting diverse traffic –Different timings are assigned in a CTB (channel time block) to separate contention-free (reservation) and contention (EDCA) access. If the CTB owner doesn’t use the reservation, other stations can always use EDCA to contend. Simple and low complexity coordination (preferably, self-regulated without any message exchange) Enabling power saving Others?? Beacon period CTB k-1 CTB k Beacon Interval N Beacon period CTB k-1 Beacon period CTB k-1 CTB k ….. BI N+X BI N+X+1 CTB k successful contention contention free (CTB k Owner) No reservation found for CTB k for # of superframes? contention free … …. DEV1

7. doc.: IEEE 802.11-09/0338r0 Submission March 2009 Chiu Ngo et al. (Samsung Electronics)Slide 7 Summary Current 802.11 ad hoc mode may not be sufficient to support diverse applications with good user experiences. Enhanced medium access with better coordination is required that enables –Fully distributed access –Guarantee access –Flexible for supporting diverse traffic –Simple and low complexity setup (self-regulated without messaging) – Power saving –etc.

8. doc.: IEEE 802.11-09/0338r0 Submission March 2009 Chiu Ngo et al. (Samsung Electronics)Slide 8 Straw-poll Question Should 802.11 WNG receive further presentations on the topic of performance improvement for 802.11 ad hoc mode? Yes: No: Abstain: