The document discusses and compares three common indoor positioning technologies: WiFi, Bluetooth, and UWB. WiFi positioning uses signal strength and fingerprinting for meter-level accuracy. Bluetooth positioning uses RSSI for proximity and positioning within a small area like a store. UWB positioning uses time of arrival with centimeter-level accuracy, making it the most precise but also higher cost than WiFi and Bluetooth. The best technology depends on the scenario and requirements for accuracy, cost and power consumption.

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WiFi vs Bluetooth vs UWB
WiFi, Bluetooth, UWB, who has higher indoor positioning accuracy?
In the context of the Internet of Everything, the acquisition and application of location
information are becoming more and more important in project implementation. Compared with
outdoor positioning, the working environment of indoor positioning is more complex and
detailed, and its technology is more diverse.
In the future, indoor positioning technology will sweep all aspects of our production and life,
such as smart factory personnel and cargo management and scheduling, production safety
management, underground parking lot car navigation, smart building personnel/visitor
positioning management, exhibition location navigation, etc.
Under normal circumstances, we can divide indoor positioning technology into:
Wi-Fi positioning
ZigBee positioning
Bluetooth positioning
UWB positioning
RFID positioning
Satellite positioning
Low-frequency trigger positioning
Base station positioning
Sonic positioning

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Light positioning
Geomagnetic positioning
Etc.
Let's discuss three common indoor positioning technologies such as WiFi, Bluetooth, and UWB.
1. WiFi
Around 2010, Wi-Fi positioning began to be applied in the field of personnel monitoring based on
location tags. In 2013, mobile phone-based Wi-Fi detection and other applications also emerged.
At present, Wi-Fi positioning is a popular indoor positioning technology. Its positioning method is
based on the signal strength propagation model method and the fingerprint identification
method.
The propagation model method of signal strength refers to the use of a certain channel fading
model assumed in the current environment to estimate the distance between the terminal and
the AP at a known location based on its mathematical relationship. If the user hears multiple AP
signals, they can pass through the three sides Positioning algorithm to obtain the user's location
information;
The fingerprint identification method is based on the propagation characteristics of Wi-Fi signals,
combining the detection data of multiple APs into fingerprint information, and comparing it with
reference data to estimate the possible position of a moving object.
Wi-Fi can be used to cover some scenes where the positioning accuracy is meter-level. This
technology is suitable for people/vehicle positioning and navigation, medical institutions,
shopping malls, theme parks, and other scenes.

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2. Bluetooth
Around 2014, Bluetooth-based positioning technology began to be applied in the field of
monitoring and positioning. In July 2017, Bluetooth mesh was officially launched. In one and a
half years, more than 105 products with Bluetooth mesh network functions have been certified,
including chip, a protocol stack, module, and terminal product suppliers.
In order to meet the growing demand of the location service market, the new Bluetooth 5.1
standard has added a new direction-finding function, which can help the device to clarify the
direction of the Bluetooth signal, and then help developers to interpret the Bluetooth proximity
solution of the device directly to achieve centimeter-level position Accurate Bluetooth
positioning system.
Location-based Bluetooth service solutions are generally divided into two categories: proximity
solutions and positioning systems. Whether it is real-time positioning or indoor positioning, the
principle is similar.
That is, the RSSI (received signal strength) mechanism is added to the data packet transmission,
and the approximate range of the product is virtualized through RSSI, and then the trilateral
measurement method is used to achieve mutual intersection The measurement algorithm is
finally completed indoor positioning.
Bluetooth positioning, as long as the device's Bluetooth function is turned on, it can be located.
Bluetooth transmission is not affected by line-of-sight, but for complex space environments, the
stability of the Bluetooth system is slightly worse, and it is greatly interfered with by noise signals,
and the price of Bluetooth devices and equipment is relatively expensive.
According to the "2019 Bluetooth Market Update", location services have become the

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fastest-growing Bluetooth solution, and its compound annual growth rate is expected to reach 43%
in the next five years.
Bluetooth positioning is mainly used to locate people in a small area, such as a single-story lobby
or a store, and has now been used by some manufacturers to promote LBS.
3. UWB
In recent years, with the maturity of UWB chip solutions and the decline in cost, domestic
companies researching UWB positioning technology continue to emerge. UWB is a wireless
positioning technology with a high transmission rate (up to 1000Mbps or more), low transmit
power, and strong penetrating ability.
Industries currently using UWB positioning technology are tunnels, chemical plants, prisons,
hospitals, nursing homes, mines, and other industries.
UWB positioning uses TDOA (Time Difference of Arrival) and AOA positioning algorithms to
analyze the label position by multiple sensors. It has the characteristics of the multipath
resolution, high accuracy, and positioning accuracy up to centimeter-level.
TDOA is a method of positioning using time difference of arrival, also known as hyperbolic
positioning. The tag card sends a UWB signal to the outside, and all base stations within the
wireless coverage of the tag will receive the wireless signal.
If there are two base stations with known coordinate points that receive the signal, and the
distance between the tag and the two base stations is different, then the time points when the
two base stations receive the signal are different.
Positioning systems based on signal time, such as UWB, need to be redeployed once they are

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blocked by a wall. With the same area, the number of rooms doubles, and the number of base
stations will also double, making it easier to deploy base stations in open scenarios.
Wireless local area network positioning is mainly used in indoor positioning. Depending on the
characteristics of the signal and the network architecture, its positioning accuracy can range from
centimeters to meters.
In different scenarios, when we choose a specific positioning technology, we must not only
consider the accuracy performance, but also the cost and power consumption.
Therefore, although UWB has the highest accuracy, other positioning technologies have their
own markets.