802.11ai – Improving WLAN System Performance 1Page 1 John Doe, Some Company Month Year doc.: IEEE 802.11-yy/xxxxr0 Nov 2013 802.11ai – Improving WLAN System Performance Date: 2013-11-06 Authors: Hiroshi Mano (ATRD)

Introduction to IEEE802.11ai, FILS Use case Nov 2013 Agenda Introduction to IEEE802.11ai, FILS Use case 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. Hiroshi Mano (ATRD)

Introduction to IEEE802.11ai, Fast Initial Link Setup (FILS) Nov 2013 Introduction to IEEE802.11ai, Fast Initial Link Setup (FILS) The initial link setup includes all operations required to enable IP packets exchange: Network and BSS discovery Authentication and association IP address configuration 802.11ai focuses to 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. Hiroshi Mano (ATRD)

Today’s Market Trends Majority of the Wi-Fi devices are portable Nov 2013 Today’s Market Trends Growth of portable device market Majority of the Wi-Fi devices are portable New application’s request (Twitter, Facebook…) Push Notification Service Quick updates High bandwidth Very SMALL CELL of each AP 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) Always-on connectivity is a must Hiroshi Mano (ATRD)

Hot Spot Environment 1/2 Nov 2013 Dense deployment: The famous ”Tokyo Metro Station” Increased 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 Hiroshi Mano (ATRD)

Nov 2013 Hot Spot Environment 2/2 Most of air time is occupied by control frame Especially undesired Probe Response frames are overflowing Frame type profile at metro station 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 Breakdown of Management frames Hiroshi Mano (ATRD)

Features of IEEE802.11ai (Scan) Nov 2013 Features of IEEE802.11ai (Scan) 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 Avoids scanning of channels with no AP BSSID of neighbor AP enables more precise active scanning Additional parameters may be included to provide more information of the neighbor BSSs Hiroshi Mano (ATRD)

Active Scanning, Expedited Scanning Procedure doc.: IEEE 802.11-yy/xxxxr0 Month Year Nov 2013 Active Scanning, Expedited Scanning Procedure If device has received a probe request, it should avoid transmitting the same probe request as transmitted 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 Hiroshi Mano (ATRD) John Doe, Some Company

Active Scanning, Probe Response Collision Avoidance doc.: IEEE 802.11-yy/xxxxr0 Month Year Nov 2013 Active Scanning, Probe Response Collision Avoidance The APs avoids sending unnecessary copies of probe responses Single copy of probe response or beacon frame is enough STA 1 Probe Request STA 2 STA2 misses the probe request transmission AP1 AP2 AP3 STA 1 Probe Request STA 2 AP1 AP2 AP3 STA 1 Probe Response STA 2 Receive probe responses AP1 AP2 AP3 Hiroshi Mano (ATRD) John Doe, Some Company

Active Scanning, Comprehensive Response doc.: IEEE 802.11-yy/xxxxr0 Month Year Nov 2013 Active Scanning, Comprehensive Response One probe response may contain information of multiple APs The total number of responses is reduced STA 1 Probe Request Chn 1 Chn 6 Request for information of other BSSs AP1 AP2 AP3 Probe Response + Neighbor List Contains information of itself (AP 2), as well as AP 1 and AP 3 or channel 6 Hiroshi Mano (ATRD) John Doe, Some Company

Active scanning, New Response Criteria doc.: IEEE 802.11-yy/xxxxr0 Month Year Nov 2013 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 Vendor specific information AP capabilities 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 Hiroshi Mano (ATRD) John Doe, Some Company

Active scanning, Probe Response Reception Time Element Nov 2013 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 Hiroshi Mano (ATRD)

Passive Scanning, Key Enhancements Nov 2013 Passive Scanning, Key Enhancements FILS Discovery (FD) frame: a new public action frame Small-size: 30-byte MAC headers + 10 to about 25 bytes FD frame body, i.e., 40 to 55 bytes for typical uses; 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; Example #1 Beacon FD frame Primary channel of the transmitter T1 Preamble Payload of FD Frame time Preamble Payload of FD Frame Example #2 Preamble Payload of FD Frame T2 time Preamble Payload of FD Frame Example #3 T3 time Hiroshi Mano (ATRD)

Reducing Sizes of the Responses Nov 2013 Reducing Sizes of the Responses AP Configuration Change Count (CCC) keeps count 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 Hiroshi Mano (ATRD)

Network Discovery, Key Enhancements Nov 2013 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. Hiroshi Mano (ATRD)

Feature of IEEE802.11ai (Higher layer setup) Nov 2013 Feature of IEEE802.11ai (Higher layer setup) Reduce the number of packet exchanges during initial link setup. All of necessary information are exchanged in 2 to 3 round trip of packet exchanges. Note: IEEE802.11ai achieves to have an established IP-Link after the set-up (ready to use for higher layer protocols / applications) This is a major difference from what we have today (IP-setup follows afterwards) and saves lots of time. Hiroshi Mano (ATRD)

Link Setup States per 802.11ai Nov 2013 Link Setup States per 802.11ai Hiroshi Mano (ATRD)

Trial report of FILS feasibility study Nov 2013 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 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 Hiroshi Mano (ATRD)

Trial report of feasibility study with FILS 2/2 Nov 2013 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 Established Link Point FILS 非接続 歩きながら移動 非接続 Service Area WPA2 Hiroshi Mano (ATRD)

Annex, use case examples that benefit from FILS Nov 2013 Annex, use case examples that benefit from FILS Hiroshi Mano (ATRD)

Nov 2013 Alternative Use Cases Automatic metering Power electric Water meter Gas meter etc.. Drive through Digital Signage V2V,V2X Hiroshi Mano (ATRD)

Feasibility Study of Automobile Application Nov 2013 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. Hiroshi Mano (ATRD)