1. doc.: IEEE 802.11-12/1126r0 Submission September 2012 Krishna Sayana, SamsungSlide 1 Wi-Fi for Hotspot Deployments and Cellular Offload Date: 2012-09-18 Authors:

2. doc.: IEEE 802.11-12/1126r0 Submission Abstract Ever increasing data traffic fueled by new devices and applications –Network deployments moving to small cells and dense deployments –A significant portion of such traffic on WiFi networks (12/936r0) As discussed in July meeting (12/910r0-Orange), increasing focus is on Wi-Fi outdoor hotspot deployments and cellular offload –Next Generation Wi-Fi should target support for these new scenarios In this presentation, we share our views on scope of PHY/MAC techniques for this purpose September 2012 Krishna Sayana, SamsungSlide 2

3. doc.: IEEE 802.11-12/1126r0 Submission Background: Wi-Fi Trends September 2012 Krishna Sayana, SamsungSlide 3 Increasing portion of total network access on Wi-Fi

4. doc.: IEEE 802.11-12/1126r0 Submission Next Generation Wi-Fi PHY PHY enhancements proposed for different application scenarios and available spectrum. MU-MIMO –Increased spectral efficiency with multi-user support OFDMA –Flexible resource allocation; Backwards compatible Uplink MU-MIMO –Simultaneous access of multiple users for symmetric traffic scenarios 6-10 GHz ac extension –Offload short-range applications when 5GHz spectrum saturates –Reuse PHY/MAC designs September 2012 Krishna Sayana, SamsungSlide 4

5. doc.: IEEE 802.11-12/1126r0 Submission Next Generation Wi-Fi MAC Goal for MAC enhancements to improve system capacity, avoid congestion (OBSS) and coexist with cellular networks –Scheduler improvements –Optimize for new PHY designs, e.g, DL-OFDMA, MU-MIMO –Coordination mechanisms –We discuss some examples September 2012 Krishna Sayana, SamsungSlide 5

6. doc.: IEEE 802.11-12/1126r0 Submission AP Scheduler Enhancements (1) Currently, EDCA/HCCA used for throughput fairness –Allows different access categories and priorities –Configurable contention based access parameters Ex: CW, IFS, CFW –Not very efficient and reduce overall throughput –Do not scale for future enhancements –PCF/HCCA not widely used –Collision with neighbor BSSs also responsible for limited gains September 2012 Krishna Sayana, SamsungSlide 6

7. doc.: IEEE 802.11-12/1126r0 Submission AP Scheduler Enhancements (2) Key techniques –Improved admission control, parameterization and coordination mechanisms –Improved TDM based access mechanisms –EDCA/HCCA parameterization improvements –In a later phase, consider PHY enhancements like OFDMA, MU- MIMO September 2012 Krishna Sayana, SamsungSlide 7

8. doc.: IEEE 802.11-12/1126r0 Submission Distributed Coordination Strategies (1) Scenario: Slow coordination, Single/Multi-vendor APs Load balancing Power control Directional beamforming Handover optimization Channel reuse in space, time and frequency AP-AP information exchange (e.g. 802.11ah, wired backhaul) September 2012 Krishna Sayana, SamsungSlide 8 AP1 AP2 STA 1 STA 2

9. doc.: IEEE 802.11-12/1126r0 Submission Distributed Coordination Strategies (2) How to introduce specification support for these schemes? Slow coordination must be robust and allow higher latency to be supported –Define requirements on latency acceptable for individual schemes Coordination targets interference management and resource allocations in multiple BSSs –Identify key parameters for exchange Resource reservations, RRM parameters, Contention access, Spatial parameters –Identify a list of schemes AP silencing, reduced power operations, transmission in null directions September 2012 Krishna Sayana, SamsungSlide 9

10. doc.: IEEE 802.11-12/1126r0 Submission Centralized Coordination Strategies (1) Scenario: Cluster of APs with a central controller; fast backhaul Dynamic joint scheduling and interference management –PHY layer coordination schemes –Semi-static coordination can also be used for interference management September 2012 Krishna Sayana, SamsungSlide 10 AP1 AP2 STA 1 STA 3 Null Steering STA 2 STA 4

11. doc.: IEEE 802.11-12/1126r0 Submission Centralized Coordination Strategies (2) Centralized coordination can be supported in a later phase Can reuse techniques developed for distributed coordination with fast exchange of parameters Spatial coordination more effective with fast coordination However some smart proprietary implementations are possible What is additionally needed to improve support in WiFi specifications? Transparent network operation and backwards compatible schemes preferred Target spec support that improves over existing implementations September 2012 Krishna Sayana, SamsungSlide 11

12. doc.: IEEE 802.11-12/1126r0 Submission Synchronization Do we need timing synchronization improvements for supporting coordination? Some timing synchronization is needed to allow access to multiple APs –E.g Can consider mechanisms such as random access procedure and timing advance to align transmission timing of multiple STAs Frame level alignment procedures for cellular/WiFi offload and coordination The requirements are dependent on target scenarios, cell size, AP density etc., –As a first priority, can target scenarios that do not need efforts in this area September 2012 Krishna Sayana, SamsungSlide 12

13. doc.: IEEE 802.11-12/1126r0 Submission WiFi Cellular Offload Offload macro cell users to WiFi APs –High level coordination between 3GPP gateway and WiFi network –Cell range extension based on network conditions Handover between APs and cellular/small cells –Improvements to WiFi roaming –Certain parameters may be exchanged between different RATs Ex: RRM, QoS, load and capability parameters Current hotspot WLAN deployments have no integration with the cellular counterparts –UE experience is not seamless September 2012 Krishna Sayana, SamsungSlide 13

14. doc.: IEEE 802.11-12/1126r0 Submission Scenarios for Study Hotspot Deployments –APs with distributed coordination/interference management capabilities Backhaul Assumptions –Latency, capacity Define relevant scenario parameters like –Density of APs, AP distribution –Number of UEs/AP, UE distribution –Channel models (Delay spread etc.,) –Traffic Types/Mix –Relative location of APs and Cellular BSs (co-located etc.,) September 2012 Krishna Sayana, SamsungSlide 14

15. doc.: IEEE 802.11-12/1126r0 Submission Objectives Develop new scenarios for study with further input from vendors/service providers/operators in WNG –Identify important metrics e.g., latency, HO delays, throughput, cell-edge performance, carrier network performance Identify schemes to –Improve performance of WiFi in dense deployments Consider new PHY techniques that can also help meet these goals? –Enable seamless WiFi cellular offload September 2012 Krishna Sayana, SamsungSlide 15

16. doc.: IEEE 802.11-12/1126r0 Submission September 2012 Krishna Sayana, SamsungSlide 16 References Carrier-Oriented-WiFi-Cellular-Offload, 12/910r0 Review of Overlapping 802.11 Networks (OBSS) Status and IEEE 802.11 Solutions, 12/936r0 Compatibility of 6-10GHz extensions with the 802.11ac PHY, 12/653r0 Improved Spectrum Efficiency for the Next Generation WLANs, 12/820r0