1. doc.: IEEE 802.11-13/0331r5 SubmissionLaurent Cariou, OrangeSlide 1 High-efficiency WLAN Date: 2013-03-19 Authors: March 2013

2. doc.: IEEE 802.11-13/0331r5 Submission November 2011 xxx, OrangeSlide 2

3. doc.: IEEE 802.11-13/0331r5 Submission November 2011 xxx, OrangeSlide 3

4. doc.: IEEE 802.11-13/0331r5 SubmissionSlide 4 Outline We propose to start a new study group to enhance 802.11 PHY and MAC in 2.4/5 GHz bands “High-efficiency WLAN” targets the key issues that should be addressed to support continued growth and competitiveness of 802.11 across a broad range of market segments Laurent Cariou, Orange March 2013

5. doc.: IEEE 802.11-13/0331r5 SubmissionSlide 5 Status In July 2012 meeting, Orange presented some requirements for 802.11 to improve the Wi-Fi experience for mobile devices, emphasizing cellular offload as a strong use case [1]. –A strawpoll proposing the creation of a study group was largely positive. –We received strong support and interest from many 802.11 actors, interested in this topic and willing to contribute. In September 2012, Orange, Huawei, Samsung, NTT and others presented further arguments [2, 5, 3, 4, 8]. Since then, we continued our work to: –clearly identify the main problems to solve in IEEE 802.11 and clarify the scope –be confident that technical approaches exist that would allow these objectives to be met During this period, it became clear that many of the key issues that should be addressed for cellular offload are common with many other market segments. “High-efficiency WLAN” enhancements have broad market appeal in multiple market segments to form a next-generation of 802.11. –We believe the current proposal has sufficient maturity to move to Study Group creation Laurent Cariou, Orange March 2013

6. doc.: IEEE 802.11-13/0331r5 Submission The mobile data explosion The mobile data explosion is a combination of three components: –increased number of mobile devices (absolute, and per area) –increased requirements for per-device data throughput –increased usage of these mobile devices Per-device data throughput –Today, a (reliable) 1 – 5 Mbps connection is adequate for a reasonable user experience with most mobile web applications, including video [6] –This minimum satisfactory throughput will grow 50% per year in the coming years [7] due to increased cloud services, higher resolution video, … Increased usage of mobile devices –The most significant contributor to the data explosion: predicted 45x growth in next 5 years 55 MB/month in 2011  2.5 GB/month in 2016 for smartphones [7] –Operators will need to deploy Wi-Fi hotspots everywhere, including outdoors –Most of the environments – residential, enterprise, public spaces – will become high density scenarios Slide 6 March 2013 Laurent Cariou, Orange

7. doc.: IEEE 802.11-13/0331r5 Submission High-Efficiency WLAN Slide 7 March 2013 The key point is the increasing usage of 802.11 in high density scenarios This relates not only to operator hotspots, but equally to enterprise, residential, retail and ad-hoc scenarios We propose “High-efficiency WLAN” as a theme to drive the next generation of 802.11 –Resulting in enhanced Quality of Experience for a broad spectrum of 802.11 users in everyday scenarios Three key focus points: –(1) To improve efficiency in dense networks with large no. of STAs –(2) To improve efficiency in dense heterogeneous networks with large no. of APs –(3) To improve efficiency in outdoor deployments Laurent Cariou, Orange

8. doc.: IEEE 802.11-13/0331r5 Submission The main issues for enhancement Slide 8 March 2013 TopicScenarios (see details in Annex 1) Issues (see details in Annex 2-3) 1. Large no. of STAs hotspots in dense areas enterprise (BYOD) weak flexibility in use of resources (time, frequency, space) to multiplex users efficiently high collisions and weak MAC efficiency with many STAs, especially with mixed traffic and legacy devices 2. Large no. of APs APs deployed by operators, businesses and consumers in the same neighborhood Wi-Fi Direct devices (Miracast, sync-and-go, etc) and personal Wi-Fi routers limited spatial capacity with OBSS due to spatial protection, interference and lack of coordination with neighboring APs lack of framework for consistent and flexible admission control, load balancing and fairness weak airtime occupation ratio for management vs data 3. Outdoor hotspots in open areas small-cell deployments weak uplink and high interference, weak non-LOS reliability weak robustness to higher delay spreads and Doppler Laurent Cariou, Orange

9. doc.: IEEE 802.11-13/0331r5 Submission Summary “High-efficiency WLAN” aims to achieve a very substantial increase in the real- world throughput achieved by each user in such scenarios –Creating an instantly recognizable improvement in Quality of Experience of the major use cases –Generating spatial capacity increase (area throughput) PHY-MAC enhancements for carrier-oriented Wi-Fi are also applicable to broad market segments (residential, enterprise, retail, …) –We propose a single SG to integrate these requirements in the overall evolution of 802.11 avoid interdependencies between SGs; timelines may not be much different in practice We believe such evolution will create a broad market appeal for multiple market segments and ecosystem players –Consumers, enterprise, operators, Wi-Fi Direct service providers, device vendors, TV/video, medical, … Slide 9 March 2013 Laurent Cariou, Orange

10. doc.: IEEE 802.11-13/0331r5 Submission Proposal and timeline We propose to start a new study group to add new PHY and MAC enhancements focused on “High-efficiency WLAN” –The scope and duration should be kept focused –Focus on the primary spectrum of 802.11 in 2.4 and 5GHz, preserving backward compatibility Main objectives of the study group will be: –Prepare use case documents, detail the list of problems and requirements –Develop performance metrics to address use cases and quantify objectives –Prepare PAR & 5C documents Slide 10 March 2013 Laurent Cariou, Orange

11. doc.: IEEE 802.11-13/0331r5 SubmissionSlide 11 Should IEEE 802.11 consider the creation of a study group to further discuss the topic of “High efficiency WLAN” ? –Yes –No –Abstain Straw Poll Laurent Cariou, Orange March 2013

12. doc.: IEEE 802.11-13/0331r5 SubmissionSlide 12 Request approval by IEEE 802 LMSC to form an 802.11 Study Group to consider High-efficiency WLAN [as described in doc 11-13-xxxx] with the intent of creating a PAR and five criteria. Moved:, Seconded:, Result: y-n-a Motion to create a Study Group Laurent Cariou, Orange March 2013

13. doc.: IEEE 802.11-13/0331r5 Submission References Slide 13 March 2013 –[1] 12/0910r0,Carrier oriented WIFI for cellular offload, Orange –[2] 12/1123r0,Carrier oriented WIFI for cellular offload, Orange –[3] 12/1126r0,Wi-Fi techniques for hotspot deployment and cellular offload, Samsung –[4] 12/1063r0,Requirements for WLAN Cellular Offload, NTT –[5] 13/0098r0,802.11: Looking Ahead to the Future – Part II, Huawei –[6]Cisco WLAN design guide for High Density –[7] Cisco VNI mobile 2012 –[8] 13/0113r0,Application and Requirements for Next Generation WLAN, Samsung Laurent Cariou, Orange

14. doc.: IEEE 802.11-13/0331r5 Submission Annexes Slide 14 March 2013 Laurent Cariou, Orange

15. doc.: IEEE 802.11-13/0331r5 Submission Hotspot deployment scenarios Hostpot deployments will scale between: –Street deployment for a blanket coverage of a neighborhood (typical cellular network pico-cell deployment) 50 APs per km², 150-200m distance between hotspots –Very high density deployments (stadiums, train stations, …) 6400 APs per km², 12-20m distance between APs 0.5 users per m² Slide 15 AP STA 160-200m MCS0 range MCS6 range MCS0 range MCS6 range Annex 1 Laurent Cariou, Orange

16. doc.: IEEE 802.11-13/0331r5 Submission Pico-cell street scenario Characteristics of outdoor street deployments: –most deployments will be made with placement below rooftop (3 - 10m): lamp poles, hanged on cables, stuck to walls… –mostly side coverage (omni or directional) –ITU Micro (UMI) model could be a good fit –deployment is costly (backhaul, site rental…). As a consequence: the distance between APs must be as high as possible (2 neighbor deployed APs will overlap close to the minimum sensitivity) – around 150-200 meters AP Tx Power is high (23-30dBm) less constraints on frequency reuse –high density of STAs, spread over the whole BSS coverage –heterogeneous dense deployment: potential high proportion of interfering APs in the coverage of hotspots indoor home or shop private APs leaking outdoors (usually in hidden node situation) –at 2.4GHz, between 15 to 20 APs in all 3 channels (beacons already occupy 20% of channel) other public hotspots coordination is feasible if they belong to the same operator, is very difficult with other APs AP STA 160-200m Annex 1 Laurent Cariou, Orange

17. doc.: IEEE 802.11-13/0331r5 Submission Stadium / train station scenario Characteristics of stadium/train station deployments: –side or overhead coverage (omni or directional) –very high user density (ex: hypothesis of 0.5 users/m²). As a consequence, the distance between APs is reduced as much as possible (2 neighbor deployed APs will overlap largely) – around 12-20 meters AP Tx Power is usually reduced (6-12dBm) high AP density: high constraints on frequency reuse: multi-BSS spatial capacity improvements – high density of STAs, regrouped over a limited range (higher MCSs) and not on the whole AP coverage (MCS0 range) – high co-channel interference coming from neighboring APs reusing the same frequencies coordination is possible via the controller – potential interference coming from soft APs more difficult to coordinate MCS0 range MCS6 range MCS0 range MCS6 range Annex 1 Laurent Cariou, Orange

18. doc.: IEEE 802.11-13/0331r5 Submission What are the main problems? High number of STAs per AP –802.11 channel access has been designed for and is effective with a limited number of users. However, with a high density of STAs:  limitations of CSMA-CA: inefficient after a certain density of STAs due to increased collisions  MAC efficiency/airtime use limitations: - much less efficient for a high number of users, each with limited throughput applications - airtime use can be very inefficient with a traffic mix (small and big packets) - a significant proportion of packets are very small - e.g. web browsing: <100B packets represent 90% UL packets and 25% DL packets -airtime use can be also very inefficient with a mix of legacy devices –management frames (e.g. probe requests/responses) consume a large fraction of the available airtime Slide 18 Annex 2 Laurent Cariou, Orange

19. doc.: IEEE 802.11-13/0331r5 Submission Illustration: collision issues with high STA density per BSS Slide 19 Average PER increases rapidly with the number of STAs, approaching 50% for 25 STAs Throughput and latency and power consumption is strongly impacted Most rate prediction algorithms in devices lower MCS when PER increases, leading to a spiraling down of throughput. Annex 2 Example with a rate prediction AARF (PER based) AARF reference: IEEE 802.11 rate adaptation: a practical approach Mathieu Lacage, Mohammad Hossein Manshaei, Thierry Turletti International Workshop on Modeling Analysis and Simulation of Wireless and Mobile Systems - MSWiM, pp. 126-134, 2004  AP sum throughput collapses Laurent Cariou, Orange

20. doc.: IEEE 802.11-13/0331r5 Submission In very high density deployment scenarios (large no. of APs) –saturation with high number of STAs per AP –channel reuse is almost impossible co-channel interference strongly limits spatial capacity problem is harder in environments without walls where propagation is very good –other interferences (adjacent-channel interference, non Wi-Fi interference) –inefficient cohabitation with tethering devices (soft APs) and Wi-Fi Direct devices –difficult to achieve consistent admission control, load balancing and fairness behavior to optimize networks even when APs deployed together Slide 20 CCA protection zone Channel reuse 3 Annex 2 What are the main problems? Typical scenario: e.g. user density: 0.5 user/m² cellular-like APs planning (with frequency reuse pattern) AP density: 6400 AP/km² (distance between neighboring APs: 14m) Laurent Cariou, Orange

21. doc.: IEEE 802.11-13/0331r5 Submission What are the main problems? In outdoor deployment scenarios –delay spread issue in typical outdoor ITU UMI channels –links can hardly be maintained in non-LOS, even with good received SNR (with Rx power below -70/75 dBm) –uplink is the limiting factor - especially with smartphones (10-12dBm Tx power) –high levels of interference –home gateways leaking outdoors minimum of 15-20 uncoordinated APs per channel (2.4GHz) under coverage (with rather small Rx power – but sufficient to cause interference, especially at BSS-edge) –saturation with a high number of STAs per AP Slide 21 Annex 2 Typical scenario: Pico-cell/AP deployment  50 to 60 APs per km²: inter-AP distance of 150-200m  500Mbps on 20000m² (80m-radius BSS) Laurent Cariou, Orange