Submission doc.: wng Slide WNG Presentation on Location Awareness Date: Authors: Nov 2010 Jim Lansford (CSR)

Submission doc.: wng Abstract This document has a discussion of location awareness issues in , to see if there are features in the 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)

Submission doc.: wng 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)

Submission doc.: wng 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)

Submission doc.: wng 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  v 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  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)

Submission doc.: wng Use Case 2: AP to Device or Device to AP  If device has GPS  Could send coordinates to AP using v  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 v coordinate exchange Jim Lansford (CSR)

Submission doc.: wng 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 v –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 k or ToF –Can do triangulation if multiple devices have k RSSI capability or if ToF were added to PHY

Submission doc.: wng Next Steps Where should we go from here?