How many infrastructure devices are needed to accurately determine a device’s location?

A localization service is part of a larger connectivity service. By using the Wi-Fi network to provide location services, native co-existence is achieved between the location and core data connectivity service. This kind of native support results in an ability to maintain the QoS of the data service, while ensuring the performance and accuracy of the location service.

The environment can play a role, and introduce multipath, which may cause the range to be overestimated. This includes building materials, the presence of RF reflectors such as HVAC metal ducting, and some eco-glass designed to reflect the sun’s rays, but also reflects RF. Often these effects are transitory for a mobile device, and a typical motion filter will remove them from the estimated path.

Location precision is inversely proportional to bandwidth. If an 80 MHz channel bandwidth results in a location precision of 1 meter, then for a 160 MHz bandwidth channel, the precision will be roughly 0.5 meters.

This depends on the implementation, but there are commercial examples of devices that can range to 6 access points at 2-3 Hz. When combined with digital maps, this results in a smooth turn-by-turn navigation experience. The ranging rate when multiple devices are positioning at the same time will also affect network utilization and needs to be considered when a network deployment is being planned.

For the Wi-Fi infrastructure venue owner, Wi-Fi Location provides a valuable additional user-facing location service (see "What are the primary uses of Wi-Fi Location?” for examples), with no additional operational cost, and may even save running costs by helping the owner maintain their network, locating access points after site remodels.

Wi-Fi Location enables a mobile client to determine its location to an accuracy of about 1 meter (at 80 MHz bandwidth), when operating within a Wi-Fi network. There is no additional hardware cost, or any significant impact on battery lifetime.

Wi-Fi CERTIFIED Location ensures a Wi-Fi product conforms to the IEEE standard with respect to the FTM protocol and can operate within the accuracy expected for range estimation. Positioning and applications, such as indoor navigation, can be supported when all participating devices have certification.          

Wi-Fi ranging estimates the distance between two devices using the FTM protocol. When three or more ranges to nearby access points at known positions are combined, the mobile device can estimate its own location (or position) on a map.

Wi-Fi Location can be used where GPS cannot. A typical location-based application is positioning and route finding inside a building (aka indoor navigation), allowing users to be directed to a specific place, thing, or product. It also enables proximity applications, which include wireless keys/locks, smart home control (actions triggered by relative positions of devices), and access-control to digital resources based on location.

Wi-Fi CERTIFIED Location™ is used for determining device location within a network by finding and connecting to access points, whereas Wi-Fi Aware is about connecting directly to other devices to publish and advertise information and services without an access point. Wi-Fi Location™ and Wi-Fi Aware can be utilized for similar uses, such as geo-fencing or personalized shopping, but Wi-Fi Location is meant to operate within Wi-Fi infrastructure to deliver precise location determination. Wi-Fi Aware is focused on connecting devices within an area of proximity without a network infrastructure.

Wi-Fi Location uses the time-of-flight (ToF) of IEEE 802.11 frames to locate a device within a network (also called round-trip-time (RTT)). It is based on the Fine Timing Measurement (FTM) protocol, enabling a mobile device to estimate its distance relative to one or more fixed position Wi‑Fi access points (APs) in the network. The mobile device can then combine these measurements, and locate itself on a floorplan, map or in latitude and longitude coordinates.

No, using Wi-Fi Location, a client device can negotiate with an access point (AP) to determine its location even when the client device is not associated with that AP.

Yes, both client and network infrastructure devices must be Wi-Fi Location enabled to support positioning.

Yes. Wi-Fi Location minimizes its impact on client battery life by allowing a device to negotiate the scheduling, and operational parameters, for a Fine Timing Measurement (FTM) protocol exchange. A single RF distance measurement can be completed in as little as 0.5 milliseconds.