1. Submission doc.: IEEE 11-13/1325r5 Hiroshi Mano (ATRD) Nov 2013 802.11ai – Improving WLAN System Performance Date: 2013-11-06 Authors: Slide 1 NameCompanyAddressPhoneemail Jarkko KnecktNokia CoroporationOtaniementie 19B 02150 Espoo Finland Jarkko.Kneckt@nokia.co m Lei WangInterDigital Communications 781 Third Ave. King of Prussia, PA 19406 858-205-7286Leiw@billeigean.com Hitoshi MoriokaAlliedtelesis R&D center K.K.8F TOC2 Bldg. 7-21-11 Nishi- Gotanda, Shinagawa-ku, Tokyo 141-0031 JAPAN hmorioka@root-hqcom Ping FangHuawei Technologies Co., Ltd. Bldg 7, Vision Software Park, Road Gaoxin Sourth 9, Nanshan District, Shenzhen, Guangdong, China, 518057 +86 755 36839346 ping.fang@huawei.com René StruikStruik Security ConsultancyToronto ON, CanadaRstruik.ext@gmail.com Santosh PandeyCisco Systems 170 W Tasman Dr, San Jose, CA, 95134, USA +1-408-8535990sanpande@cisco.com Cherian, GeorgeQualcomm 5775 Morehouse Dr, San Diego, CA, USA +1 858 651 6645gcherian@qti.qualcomm.com Marc Emmelmann Self-Employed & Allied Telesis R&D Center emmelmann@ieee.org Hiroshi ManoAlliedtelesis R&D center K.K.8F TOC2 Bldg. 7-21-11 Nishi- Gotanda, Shinagawa-ku, Tokyo 141-0031 JAPAN hmano@root-hq.com

2. Submission doc.: IEEE 11-13/1325r5 Agenda Introduction to IEEE802.11ai, FILS Key use case for 11ai 802.11ai features in details Trial report of the FILS feasibility study Current status of IEEE802.11ai Note: This presentation has not been approved by IEEE802.11ai task group as an official overview document. It has been proposed by the authors based on the approved submissions as of Nov 2013. Slide 2 Hiroshi Mano (ATRD) Nov 2013

3. Submission doc.: IEEE 11-13/1325r5 Today’s Market Trends Growth of portable device market - Majority of the Wi-Fi are portable devices. True mobile usage: Users frequently pass through (isolated) hot spots while on the move The dwell time of an user within a cell is short Isolated hot spots cause frequent initial association /authentication (link setup) New application’s request (Twitter, Facebook…) Push Notification Service Short and quick updates High bandwidth Very SMALL CELL of each AP So even with short dwell time under a given AP, always-on connectivity is a must Slide 3 Hiroshi Mano (ATRD) Nov 2013

4. Submission doc.: IEEE 11-13/1325r5 Hot Spot Environment 1/2 Dense deployment: The famous “Tokyo Metro Station” Increasing amount of spectrum & number of networks & number of devices Signaling overhead, exchange of unnecessary information QoS violation Use of WLAN offloading is increasing It is equally important to shorten the link setup time as it is to shorten the data transmission time Shorter scanning reduces power consumption of the device Slide 4 Hiroshi Mano (ATRD) Nov 2013

5. Submission doc.: IEEE 11-13/1325r5 Hot Spot Environment 2/2 Most of air time is occupied by management frame. Especially undesired Probe Response frames are overflowing KDDI’s report Understanding the current situation of public Wi-Fi usage. 13/11-13-0523-02 hew-understanding- current-situation- of-public-wifi- usage.pptx Slide 5 Hiroshi Mano (ATRD) Nov 2013 Breakdown of Management frames Frame type profile at metro station

6. Submission doc.: IEEE 11-13/1325r5 Introduction to 11ai Fast Initial Link Setup (FILS) The initial link setup includes all operations required to enable packets exchange. The main operations include: Network and BSS discovery Authentication and association Higher layer setup such as IP address configuration FILS focuses on an environment where mobile users are constantly entering and leaving the coverage area of an existing extended service set (ESS). Every time the mobile device enters an ESS, the mobile device has to do an initial link set-up. This requires efficient mechanisms that: (a) scale with a high number of users simultaneously entering an ESS (b) minimize the time spent within the initial link set-up phase (c) securely provide initial authentication. Slide 6 Hiroshi Mano (ATRD) Nov 2013

7. Submission doc.: IEEE 11-13/1325r5 Network and BSS discovery: Scanning procedure changes More control to scanning procedures: Terminating the ongoing scan More reporting options of the scanning result Immediate reporting Reporting after a channel is scanned Legacy, reporting after scanning is completed Announcing one or more neighbor BSS or channel information in Beacon, Probe Response and Fast Discovery (FD) frame Reduce chances of scanning channels with no AP BSSID of neighbor AP enables more precise active scanning More information on neighbor BSSs may be provided Slide 7 Hiroshi Mano (ATRD) Nov 2013

8. Submission doc.: IEEE 11-13/1325r5 Active Scanning, Expedited Scanning Procedure STA avoids sending unnecessary Probe Request: If a device has received a Probe Request, it should avoid transmitting of a Probe Request for same APs Slide 8 Hiroshi Mano (ATRD) Nov 2013 STA 1 Probe Request STA 2 Delay probe request transmission AP1 AP2 AP3 STA 1 Probe Response STA 2 Abort probe request transmission AP1 AP2 AP3

9. Submission doc.: IEEE 11-13/1325r5 Active Scanning, Probe Response Collision Avoidance AP avoids sending unnecessary Probe Responses: Single copy of Probe Response or Beacon frame is enough Slide 9 Hiroshi Mano (ATRD) Nov 2013 STA 1 Probe Request STA 2 STA2 send Probe Request for same APs AP1 AP2 AP3 STA 1 Probe Response STA 2 Receive probe responses AP1 AP2 AP3 STA 1 Probe Request STA 2 AP1 AP2 AP3

10. Submission doc.: IEEE 11-13/1325r5 Active Scanning, Comprehensive Response One Probe Response may contain information of multiple APs The total number of Probe Request and Probe Responses is reduced STA 1 Probe Request Chn 1 Chn 6 Request for information of other BSSs AP 1 AP 2 AP 3 STA 1 Probe Response + Neighbor List Contains information of itself (AP 2), as well as AP 1 and AP 3 of Channel 1 and Channel 6 Chn 1 Chn 6 AP 1 AP 2 AP 3 Nov 2013 Slide 10 Hiroshi Mano (ATRD)

11. Submission doc.: IEEE 11-13/1325r5 Active scanning, New Response Criteria Probe Request contains criteria to transmit Probe Response. Response is transmitted only if the criteria is met Criteria include: Reception power AP’s channel access delay, capabilities STA’s QoS requirement Vendor specific information etc. STA 1 Probe Request Criteria for AP delay performance & RSSI AP1 AP2 AP3 STA 1 Probe Response Probe response is transmitted if all the criteria are met AP1 AP2 AP3 Nov 2013 Slide 11 Hiroshi Mano (ATRD)

12. Submission doc.: IEEE 11-13/1325r5 Active scanning, Probe Response Reception Time Element The transmitters of the Probe Request may indicate how long the transmitter will be available to receive Probe Responses Probe Response Reception Time is set to MAX_Probe_Response_Time Slide 12 Hiroshi Mano (ATRD) Nov 2013

13. Submission doc.: IEEE 11-13/1325r5 Passive Scanning, Key Enhancements FILS Discovery (FD) frame: a new public action frame Small-size: MAC headers + FD frame body, 40 to 55 bytes for typical uses; Only one mandatory information element: SSID; Optional information items: AP’s Next TBTT, AP-CCC, Access Network Options, Capability, Security, Neighbor AP information. FD frame is transmitted between Beacon frames, for a fast AP/Network discovery; FD frame may be transmitted as a non-HT duplicate PPDU, enabling a larger channel than 20MHz; Slide 13 Hiroshi Mano (ATRD) Nov 2013 Payload of FD Frame Primary channel of the transmitter Preamble Payload of FD Frame Preamble T2 time Example #1 T1 time T3 time Example #2 Example #3 Beacon FD frame

14. Submission doc.: IEEE 11-13/1325r5 Reducing Sizes of the Responses AP Configuration Change Count (CCC) keeps track of changes of the parameters in Probe Response and Beacon One octet in length AP-CCC does not consider changes of BSS Load, Average Access Delay and other rapidly changing parameters Slide 14 Hiroshi Mano (ATRD) Nov 2013

15. Submission doc.: IEEE 11-13/1325r5 Control allowed STAs for concurrent initial links Differentiated Initial Link Setup element can be set by AP to control allowed STA for concurrent initial links Conditions for STAs can be set by AP including: ILS User Priority MAC Address Filter Vendor Specific Category Link Setup Bursty Slide 15 Hiroshi Mano (ATRD) Nov 2013

16. Submission doc.: IEEE 11-13/1325r5 Network Discovery, Key Enhancements GAS query enhancement by using an AP white-list A new IE with one or multiple 6-byte BSSIDs in GAS request to indicate the AP(s) that the requesting STA wants to query. GAS traffic reduction by using GAS Configuration Sequence Number A new IE with an 1-byte unsigned integer: indicating the version number of AP’s GAS configuration information set; monotonically incrementing whenever there is any change in the AP’s GAS configuration information set; Used in Beacon and/or Probe Response. Slide 16 Hiroshi Mano (ATRD) Nov 2013

17. Submission doc.: IEEE 11-13/1325r5 Feature of IEEE802.11ai (Higher layer setup) Significant reduction in setup signaling: Authentication, 4-way handshake, Association & Higher layer setup including IP address assignment completed in 2 roundtrip signaling messages Fast authentication & FILS IP address assignment speeds up the authentication & IP Address assignment procedure Slide 17 Hiroshi Mano (ATRD) Nov 2013 3 rd Party (DHCP Server) 3 rd Party (DHCP Server) DHCP Messages, etc.

18. Submission doc.: IEEE 11-13/1325r5 Link Setup States per 802.11ai Slide 18 Hiroshi Mano (ATRD) Nov 2013

19. Submission doc.: IEEE 11-13/1325r5 FILS Key Establishment with TTP STA AP Association Request Beacon/Probe Resp. Authentication Request Authentication Response Association Request Key Establishment Key Confirmation Secret keys TTP {(STA: K STA ), (AP: K AP ), …} FILS authentication with online TTP:  TTP actively assists STA and AP in deriving shared keying material (hence, “online”)  Two flavors: with or without “Perfect Forward Secrecy” (PFS) NOTE: With “PFS”, TTP usually does not learn shared key STA-AP, nor can re- compute past sessions should node get compromised (in short: better security) Requires STA and AP to share secret key with same TTP (e.g., via ISPs that have pre- existing business relationships) K AP K STA Nov 2013 Slide 19 Hiroshi Mano (ATRD)

20. Submission doc.: IEEE 11-13/1325r5 FILS Key Establishment w/o. TTP STA AP Association Request Beacon/Probe Resp. Authentication Request Authentication Response Association Request Key Establishment Key Confirmation Publi c keys CA {Cert STA, Cert AP, …} FILS authentication without online TTP:  STA and AP can derive shared keying material and authentication directly, via use of certificates (so, no need for any active involvement third party for authentication)  Third party may still be involved for authorization or for configuration (as with all FILS key establishment protocols) Requires STA and AP to certify their own public key with some CA (e.g., during manufacturing) CA root key Nov 2013 Slide 20 Hiroshi Mano (ATRD)

21. Submission doc.: IEEE 11-13/1325r5 Adding “piggy-backed info” to protocol flows … STA AP Association Request Beacon/Probe Resp. Authentication Request Authentication Response Association Request Key Establishment Key Confirmation TTP Services + piggy-backed info response + piggy-backed info request Authentication help Configuration help IP address assignment Authorization Subscription credentials Piggy-backing info along FILS authentication protocol:  Higher-layer set-up, including IP address assignment  Authorization functionality, subscription credentials, etc. See details elsewhere in presentation Nov 2013 Slide 21 Hiroshi Mano (ATRD)

22. Submission doc.: IEEE 11-13/1325r5 Trial report of FILS feasibility study The effect of reducing packet exchange was evaluated by field test in Japan The details are reported in IEEE802.11 as, https://mentor.ieee.org/802.11/dcn/13/11-13-0323-02-00ai-tgai- experimental-test-report-of-fils.pptx https://mentor.ieee.org/802.11/dcn/13/11-13-0323-02-00ai-tgai- experimental-test-report-of-fils.pptx FILS STAs completed the association process in significantly less time than WPA STAs  More time within the AP coverage for (user) data exchange The large number of link setup frame exchanges for WPA2 STAs (as compared to FILS STAs) made them vulnerable. If retransmission of a lost frame did not succeed after three attempts, the association process had to restart from the beginning This field trial did only consider the higher layer set-up features while using legacy scanning. We expect FURTHER performance improvement when the FILS scanning features are in use Slide 22 Hiroshi Mano (ATRD) Nov 2013

23. Submission doc.: IEEE 11-13/1325r5 Trial report of feasibility study with FILS 2/2 20 FILS and 20 WPA2 are entering the service area. Measured the distance of STA and AP where STA establish link successfully and received http contents. Measured the time from Association/FILS request to IP address assignment propriety application. http://www.youtube.com/watch?v=xOKaVOPWXTU 90% (18/20) FILS STA established link before arriving at in the front of AP 85% (17/20) WPA2 established link since they passed in the front of AP Average link setup time from FILS request to IP address assignment is 0.742 Sec Average link setup time from Association request to IP address assignment is 21.599 Sec FILS Service Area WPA2 非接続 Established Link Point Nov 2013 Slide 23 Hiroshi Mano (ATRD)

24. Submission doc.: IEEE 11-13/1325r5 ANNEX USE CASE EXAMPLES THAT BENEFIT FROM FILS Slide 24 Hiroshi Mano (ATRD) Nov 2013

25. Submission doc.: IEEE 11-13/1325r5 Alternative Use Cases Automatic metering Power electric Water meter Gas meter etc.. Drive through Digital Signage V2V,V2X Slide 25 Hiroshi Mano (ATRD) Nov 2013

26. Submission doc.: IEEE 11-13/1325r5 Feasibility Study of Automobile Application Fast initial link setup enables opportunistic vehicle to vehicle communication. Toyota InfoTechnology Center measured the number of user text message exchanges during specific time period. Assumption Air coverage: 50m Vehicle speed: 40km/h （ 11m/Sec ） Available communication time : 5Sec WPA2: More than 4Sec communication time is required to exchange messages. FILS: it is available to exchange messages under short communication time. Y: Number of exchanged messages X: Communication time This measurement did only consider the higher layer set- up features while using legacy scanning. We expect FURTHER performance increase if the stations implemented the new scanning features. Slide 26 Hiroshi Mano (ATRD) Nov 2013