1. Submission doc.: 11-10-1239-00-0wng Slide 1 802.11 WNG Presentation on Location Awareness Date: 2010-11-09 Authors: Nov 2010 Jim Lansford (CSR)

2. Submission doc.: 11-10-1239-00-0wng Abstract This document has a discussion of location awareness issues in 802.11, to see if there are features in the 802.11 PHY and MAC that need to be added to support location based services for regulatory and asset tracking purposes. Slide 2 Nov 2009 Jim Lansford (CSR)

3. Submission doc.: 11-10-1239-00-0wng The Problem & Market Increasing need for Wi-Fi devices to know position TV White Spaces - Mode 2 devices: location +/- 50 meters Mandatory for FCC certification…also likely to be mandatory for Ofcom 5GHz Requirement to avoid airport radar Wi-Fi Direct – complex global regulatory requirements E911 – FCC will require AP or handset in VoIP system to know position Asset tracking - If an AP or other device knows its location, can it infer location of other devices well enough to track? Location will be required for many future Wi-Fi systems –WiFi-based Real Time Location Systems will become an $800 million dollar market by 2012 (ABI Research, 2007) Jim Lansford (CSR)

4. Submission doc.: 11-10-1239-00-0wng Existing Techniques For position fixing in a Wi-Fi device: –If available: GPS (or similar satellite systems) –If available: aGPS/eGPS Using CELLID, Wi-Fi AP location databases, or similar –Lots of work on proprietary systems: Based on BSS database lookup, TDoA, AoA, or fingerprinting Propagating position information around a BSS –802.11k standardized RSSI measurements –802.11v is standardizing the formats for sending RSSI + geolocation (from GPS/aGPS) around the network Jim Lansford (CSR)

5. Submission doc.: 11-10-1239-00-0wng Use Case 1: AP to AP  One or both AP’s can have a known position  Established from database, site survey at installation, or GPS  802.11v allows AP’s to distribute this position information to all devices in the BSS  Since many (if not most) AP’s have at least two antennas (for diversity or 2x2 MIMO), could use RF positioning methods to infer approximate position of AP’s with unknown coordinates  Since both AP’s have dual antennas (or 3 or 4 for MIMO) AP’s could collaborate to improve estimates  802.11 PHY could also add “Time of Flight” (ToF) to measure range  If no absolute position available, relative position may still be useful for asset tracking  TV White Spaces (802.11af) requires absolute position, however AoA TDoA ToF Jim Lansford (CSR)

6. Submission doc.: 11-10-1239-00-0wng Use Case 2: AP to Device or Device to AP  If device has GPS  Could send coordinates to AP using 802.11v  AP could infer its position using position fixing (AoA/TDoA/ToF)  If AP knows its coordinates but device does not  AP does position fix on device, calculates its approximate coordinates, then sends to device  This will be ideal for RF tags, legacy devices, and “dumb” Wi-Fi stations – asset tracking  If both have GPS  Can calculate precise range and bearing using 801.11v coordinate exchange Jim Lansford (CSR)

7. Submission doc.: 11-10-1239-00-0wng Jim Lansford (CSR) Use Case 3: Device to Device Wi-Fi Direct doesn’t have a fixed AP If one device has GPS/aGPS: –Can distribute its position using 802.11v –If only one antenna, can only give range estimate Using RSSI, ToF or fingerprinting –Required for Mode 2 TVWS (802.11af) devices If no device has absolute location coordinates –Still useful for asset tracking –Can only get range estimates from single antenna (RSSI/fingerprinting) using 802.11k or ToF –Can do triangulation if multiple devices have 802.11k RSSI capability or if ToF were added to 802.11 PHY

8. Submission doc.: 11-10-1239-00-0wng Next Steps Where should we go from here?