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doc.: IEEE 802.11-13/0331r5
Submission Laurent Cariou, OrangeSlide 1
High-efficiency WLANDate: 2013-03-19
Name Company Address Phone email
Laurent Cariou Orange 4 rue du Clos Courtel 35512 Cesson Sevigne France
+33 299124350 [email protected]
Thomas Derham Orange 9F Keio Shinjuku Oiwake Bldg. Shinjuku 3-1-13, Tokyo, Japan
+81 3 5312 8563 [email protected]
Jean-Pierre Le Rouzic Orange 4 rue du Clos Courtel 35512 Cesson Sevigne France
+33 299124893 [email protected]
Dapeng Liu China Mobile
Unit2, 28 Xuanwumenxi Ave,Xuanwu District, Beijing 100053 China
+86-13911788933
Chunju Shao China Mobile
Unit2, 28 Xuanwumenxi Ave,Xuanwu District, Beijing 100053 China
+86-13911281253
Fang Xie China Mobile
Unit2, 28 Xuanwumenxi Ave,Xuanwu District, Beijing 100053 China
+86-13910630612
Harry R Worstell AT&T [email protected]
Hemanth Sampath Qualcomm Qualcomm, San Diego [email protected]
Gwendolyn Barriac,
Qualcomm, Qualcomm, San Diego [email protected]
VK Jones
Qualcomm,
Qualcomm, San Jose
Rolf de Vegt Qualcomm,
Qualcomm, San Jose
Authors:
March 2013
doc.: IEEE 802.11-13/0331r5
Submission
November 2011
xxx, OrangeSlide 2
Name Affiliations Address Phone email
Juho Pirskanen Renesas Mobile Corporation
Insinöörinkatu 41, 36200 Tampere Finland
+358-503636632 juho. [email protected]
Timo Koskela Renesas Mobile Corporation
Elektroniikkatie 13, 90590 Oulu, Finland
+358-50-4876991 [email protected]
Anna Pantelidou Renesas Mobile Corporation
Elektroniikkatie 13, 90590 Oulu, Finland
Hong Wei Renesas Mobile Corporation
Christopher Williams Ericsson 603 March Road, Kanata, Ontario, Canada K2K2M5
613-254-7070, x123
Stephen Rayment
Ericsson 603 March Road, Kanata, Ontario, Canada K2K2M5
613-254-7070, x112
Minho Cheong ETRI 161 Gajeong-dong, Yuseong-gu, Daejeon, Korea
+82 42 860 5635 [email protected]
Jae Seung Lee ETRI 161 Gajeong-dong, Yuseong-gu, Daejeon, Korea
+82 42 860 1326 [email protected]
Dave Halasz Self [email protected]
Ron Murias Interdigital [email protected]
Lei Wang Interdigital [email protected]
Jianhan Liu Mediatek
ChaoChun Wang Mediatek
Vish Ponnampalam Mediatek
James Wang Mediatek
Jim Lansford CSR [email protected]
doc.: IEEE 802.11-13/0331r5
Submission
November 2011
xxx, OrangeSlide 3
Name Affiliations Address Phone email
Hongyuan Zhang Marvell [email protected]
Bruce Kraemer Marvell
Sudhir Srinivasa Marvell
Sagar Tamhane Marvell
Su Khiong Yong Marvell
Paul Lambert Marvell
doc.: IEEE 802.11-13/0331r5
Submission Slide 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
doc.: IEEE 802.11-13/0331r5
Submission Slide 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
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
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
doc.: IEEE 802.11-13/0331r5
Submission
The main issues for enhancement
Slide 8
March 2013
Topic Scenarios(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
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
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
doc.: IEEE 802.11-13/0331r5
Submission Slide 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
doc.: IEEE 802.11-13/0331r5
Submission Slide 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: <name>, Seconded: <name>, Result: y-n-a
Motion to create a Study Group
Laurent Cariou, Orange
March 2013
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
doc.: IEEE 802.11-13/0331r5
Submission
Annexes
Slide 14
March 2013
Laurent Cariou, Orange
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
APAP
STA
160-200m
MCS0 range
MCS6 range
MCS0 range
MCS6 range
Annex 1
Laurent Cariou, Orange
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
APAP
STA
160-200m
Annex 1
Laurent Cariou, Orange
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
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 theavailable airtime
Slide 18
Annex 2
Laurent Cariou, Orange
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.
0 20 40 60 80 100 1205
10
15
20
25
30
35
AP
Sum
Thr
ough
put [
Mbp
s]
STA Number
AP Sum Thrp [Mbps]
MCS7AARF
0 20 40 60 80 100 12010
20
30
40
50
60
70
Avg
STA
FER
[%]
STA Number
Avg. STA PER [%]
MCS0MCS4
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
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/m²cellular-like APs planning (with frequency reuse pattern)AP density: 6400 AP/km² (distance between neighboring APs: 14m)
Laurent Cariou, Orange
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 deployment50 to 60 APs per km²: inter-AP distance of 150-200m500Mbps on 20000m² (80m-radius BSS)
Laurent Cariou, Orange
