doc.: IEEE /1123r0 SubmissionLaurent Cariou, OrangeSlide 1 Carrier-oriented WIFI for cellular offload Date: Authors: Sept 2012

doc.: IEEE /1123r0 SubmissionSlide 2 Abstract Presentation for WNG SC September 2012 Laurent Cariou, Orange Sept 2012

doc.: IEEE /1123r0 SubmissionSlide 3 Status In July meeting, we presented some requirements for WIFI technology in order to efficiently support cellular offload use case [1]. The following strawpoll was largely positive. Since the July meeting, we received strong support and interest from many WIFI actors, interested in this topic and willing to contribute. We are now in the process of clearly evaluating the scope of a future study group. –studies are still required of course to clearly quantify the issues and have a better view on the solutions In the meanwhile, we initiated discussion with other operators (present or not in IEEE802.11) to collect their prioritized requirements and to define clear scenarios for evaluation Laurent Cariou, Orange Sept 2012

doc.: IEEE /1123r0 Submission Content of the presentation/session First objective: Present further arguments to understand the objectives of the proposed action Second objective: Recall the main requirements and discuss on priorizations 4 Sept 2012 Slide 4Laurent Cariou, Orange

doc.: IEEE /1123r0 Submission Background – need for cellular offload (1/2) Mobile data traffic is envisonned to continue its tremendous growth in incoming years –lead by smartphone and tablets traffic, especially video All mobile operators are facing great difficulties for deploying, exploiting their networks while maintaining sufficient margin –clear decoupling between traffic and revenue Sept 2012 Slide 5Laurent Cariou, Orange

doc.: IEEE /1123r0 Submission Background – need for cellular offload (2/2) To support this traffic, classical « linear » solutions for increasing capacity in the radio access network are not sufficient anymore –Licensed spectrum is not sufficient –Public perception of electromagnetic waves Densification of the network with small cell deployements is seen as a major solution Such heterogeneous networks takes benefit of LTE pico, femto and micro cells but of course also of WIFI hotspots –Small cells increase spectral reuse and increase datarates by getting closer to the user –WIFI enables to make use of unlicensed spectrum We are not in a situation where the Wi-Fi offload is a nice to have feature, we are in a situation where it’s mandatory to offload traffic from cellular network and to enhance user experience Sept 2012 Slide 6Laurent Cariou, Orange

doc.: IEEE /1123r0 Submission Background – towards transparent handovers between 3G/4G and WIFI Adoption of WIFI public APs is still slowed down by several constraints: discovery, authentication, access cost, security… The arrival of hotspot 2.0 will ease automatic selection of WIFI and 3G/4G Another trigger will be the adoption of data offload architectures defined in 3GPP, from non-seamless mobility up to transparent IP mobility. All these evolutions will strongly increase WIFI hotspot deployments Sept 2012 Slide 7Laurent Cariou, Orange

doc.: IEEE /1123r0 Submission Background – need for cellular offload Massive deployment of hotspots have already started –for economic reasons –to improve user experience –as there are new business models around WIFI And hotspots are going to be deployed in a wide range of locations New user generation First user generation % of current users At home In a mobile field At a friends place At work At school Library Cyber café Source: Next generation users (Oxford internet institute) Sept 2012 Slide 8Laurent Cariou, Orange

doc.: IEEE /1123r0 Submission Heterogeneous WIFI deployments to efficiently support offload A great portion of traffic is at home. This is obviously the first target –Many operators can benefit from home APs, especially if they are fix and mobile operators. These indoor home APs will increase in the future. In order to leverage on existing backhaul, indoor private WIFI APs will serve indoor and outdoor clients –with a private SSID and a public SSID (community WIFI) Operators will deploy WIFI APs everywhere, including outdoors, integrated with 3G/4G pico, micro and femto-cells or in complementary locations as stand-alone APs –such deployments will be done indoor and outdoor –by 2013, 79% of service providers are planning to deploy WIFI for street coverage Very dense public places are already a strong target for WIFI APs deployments and this trend will intensify –stadiums, convention center, outdoor events… Sept 2012 Slide 9Laurent Cariou, Orange

doc.: IEEE /1123r0 Submission Context - General objective The aim is not to define the mechanisms to offload traffic from cellular to WIFI –mostly done in 3GPP, requires however a strong liaison and coordination but to improve WIFI technology in order to reach a “trusted state” not only for authentication, security… but also for data transmissions Sept 2012 Slide 10Laurent Cariou, Orange

doc.: IEEE /1123r0 Submission Context – What we are looking for Operators are going to rely quite strongly on WIFI technology in the future We want to make sure that its evolution fits the requirements –WIFI need to be efficiently designed for the different hotspot scenarios heterogeneity of deployments leads to heterogeneous requirements Efficient use of home APs as hotspots, improvement of outdoor stand-alone APs and clusters of APs, adaptation to very dense environments –and can ensure stable and predictable performance (quality of experience and throughput/capacity) over time in unstable environments with high user density, with high AP density (including soft APs), in the presence of legacy devices, of WIFI or non WIFI interferences, … –that WIFI can ensure its performance in the long term, especially by finding solutions against the envisioned congestion in very dense environments at 2.4 and 5GHz. Sept 2012 Slide 11Laurent Cariou, Orange

doc.: IEEE /1123r0 Submission Background - types of offloaded traffic and priorization Most of current 3G traffic is best effort traffic. Even video which is the main capacity demanding service is currently treated as best effort. –Things might change as very robust QoS mechanisms are defined in LTE, but offloaded traffic will mainly be best effort traffic. –Depending on WIFI QoS performance, offloading specific QoS operator traffic may be envisioned in the long term. –Once VoLTE is deployed, VoWIFI may well be an important usage case, in deep indoor locations where cellular signal is marginal and no femtos are deployed. But “best effort” does not mean “no concern about throughput/QoE” –Customers expect good QoE for OTT/best effort traffic too Management of QoS in cellular networks is currently done by applying fairness control in base stations and enabling traffic priorization –proportional fairness: efficiently balance user throughput to improve cell capacity and protect fairness –channel preemption for emergency, favored access to premium users, … Sept 2012 Slide 12Laurent Cariou, Orange

doc.: IEEE /1123r0 SubmissionSlide 13 In July, we presented several requirements Laurent Cariou, Orange Enable the efficient support of high number of users per AP with fairness control –requires the improvement of cell-edge (BSS-edge) throughput –EDCA/HCCA adaptations, multiple access schemes for a better MAC efficiency Improve robustness (throughput and QoS) to interference especially in high density environments –better robustness to congestion in very dense environments (high number of STAs and APs (including undeployed soft APs): better MAC efficiency –interference management/coordination to improve spectral reuse (frequency/time/space) Ensure the adaptation to outdoor deployments –improve spectral reuse/protection trade-off, robustness against more hidden nodes –range extension?, support for longer delay spreads? (still need to evaluate the need) Sept 2012

doc.: IEEE /1123r0 SubmissionSlide 14 A major part of the scope focuses on improving efficiency (BSS capacity, MAC efficiency, QoE per user) in high density environments (High number of users per BSS, high number of OBSS) Discussion Strawpoll: Would you be in favor of including this objective in the scope? Another important part of the scope focuses on adaptations to outdoor deployments Discussion Strawpoll: Would you be in favor of including this objective in the scope? Scope clarifications/discussions Laurent Cariou, Orange Sept 2012

doc.: IEEE /1123r0 SubmissionSlide 15 PHY layer improvements might provide important solution to fulfill the objectives –multiple access scheme, interference cancellation/avoidance Strawpoll: Would you be in favor of a PHY/MAC improvement group or of a MAC only group? Management: During the discussion last meeting, mobility improvements between APs have been mentioned as an important feature. –We need to clarify the priorization with the main operators, but our first though is that the most important mobility is 3G-LTE/WIFI mobility which is defined in 3GPP. Scope clarifications/discussions Laurent Cariou, Orange Sept 2012

doc.: IEEE /1123r0 Submission Annexes Sept 2012 Slide 16Laurent Cariou, Orange

doc.: IEEE /1123r0 Submission Context – What we are looking for WIFI successive generations have always provided important peak throughput increases –it was the major selling point ac has defined a comfortable increase of throughput compared to 11n, which should enable progressive throughput increase for a long period of time. We believe an evolution of WIFI in 2.4 and 5GHz should be focused on ensuring/improving the robustness/preservation of these high throughputs in highly congested environments. –Increase capacity by spectral reuse improvements Sept 2012 Slide 17Laurent Cariou, Orange

doc.: IEEE /1123r0 Submission Clarifications of the needs to improve WIFI adaptation to high density One of the big challenge in the future is to deal with high density user deployments. Such deployments require to support: –very high capacity demand –with the growing presence of interfering soft APs, WIFI direct devices Slide 18Laurent Cariou, Orange Occurance of different types of paquets Issues and risks –the risk of congestion in these environements is very high –in such high density situations, especially with many active APs, the proportion of data transmission over control/management transmission is considerably reduced and could lead to a complete inefficiency of WIFI –several papers including [4] try to evaluate this MAC efficiency issue. Sept 2012

doc.: IEEE /1123r0 Submission Main identified problems –high proportion of management/control transmission –channel occupation of low throughput transmissions –bad exploitation of time/frequency/space resources We need PHY/MAC improvments, that could enable more efficient use of the resources –traffic shaping for a better fairness –OFDMA can probably enable better MAC efficiency with a high number of low throughput users –Techniques allowing simultaneous transmissions of multiple users, including legacy devices can also be very important –Coordination between APs would enable a better frequency/time/spatial frequency reuse light coordination between neighbors: power adaptation, channel selection, bandwidth selection better coordination between the APs belonging to the same deployed network (APs managed by a controller or array of co-located APs) –interference avoidance, multi-MAC association Slide 19Laurent Cariou, Orange Clarifications of the needs to improve WIFI adaptation to high density Sept 2012

doc.: IEEE /1123r0 Submission Clarifications on the need to improve average throughput by improving cell-edge Operators will deploy many stand-alone APs as small cells. the objective of small cells is to offload as much traffic as possible from the overlaying macrocell –the strategy is therefore that all STAs in the coverage of the small cells connect to it (small cell range extension in LTE-A) –if cell-edge users have a too strong impact on the performance of the whole WIFI cell, this strategy is not applicable. We therefore need to find solutions for this. Cell range-extension Macro-cell Small cell Slide 20Laurent Cariou, Orange Sept 2012

doc.: IEEE /1123r0 SubmissionSlide 21 Assuming an overlay macro-deployment, [2] presents a comparison of capacity increase between co-channel LTE picocells and WIFI hotspots, using LTE hetnets evaluation methodology as defined in [3] In these results, LTE picocells significantly outperforms WIFI –mostly due to increased pico-cell range compared to WIFI thanks to lower throughputs, better receiver sensitivity, and better per-tone SINR Laurent Cariou, Orange D3 Large Macro Cell Scenario, Hotspot (20/30) Distribution.D1 Small Macro Cell Scenario, Hotspot (20/30) Distribution Clarifications on the need to improve average throughput by improving cell-edge Sept 2012

doc.: IEEE /1123r0 Submission References [1] wng-Carrier-Oriented-WiFi- Cellular-Offload [2] A Comparison of LTE Advanced HetNets and WiFi – Qualcomm [3] 3GPP TR Technical Specification Group Radio Access Network [4] van Bloem, J.W.H. and Schiphorst, Spectrum Utilization and Congestion of IEEE Networks in the 2.4 GHz ISM Band. Journal of Green Engineering, 2012 Sept 2012 Slide 22Laurent Cariou, Orange