What Are the Benefits of Indoor Navigation?
In general, indoor navigation is used to provide the following benefits:
- Better user experience for users navigating indoor spaces where GPS is not practical
- Improving worker efficiency in commercial buildings
- Improving traffic flow in congested areas
- Allowing users to find each other in a facility
- Enabling smart building operations and enhancements
- Using collected location data to optimize the workflow and improve the usability of the space
The benefits provided by an implementation depend on the goals of the specific application in question. Examples of applications that utilize indoor navigation include:
- Shopping malls and supermarkets
- Theme parks
- Healthcare facilities
- Conference centers
- Dining and restaurants
The Most Critical Attributes for Wireless Technologies Utilized in Indoor Navigation
There are a few key attributes that need to be considered in wireless technologies utilized for indoor navigation. These are:
- Privacy and security
- Positioning resolution (accuracy and latency)
- Ubiquity and adoption
Comparison of the Wireless Technologies Most Suitable for Indoor Navigation
The most suitable wireless technologies for indoor navigation applications are:
- Bluetooth® Low Energy
- Ultra-wideband (UWB)
Let’s talk a bit about how each of them fits within the application of indoor navigation.
Bluetooth Low Energy
Bluetooth® Low Energy is the most common wireless technology used in indoor navigation systems, and for a few good reasons. Some of the most important benefits of using Bluetooth Low Energy for indoor navigation include:
- Secure and private implementation
- Wide adoption and uniquity across smartphones globally
- Support for large scale deployments
After Apple released its standard format for iBeacon in 2013, Bluetooth beacons took off and became widely adopted in many use cases, especially in retail marketing and indoor navigation applications.
Traditionally, Bluetooth Low Energy beacons have been used as a popular solution for indoor navigation systems. The basic principle behind these systems is to install Bluetooth beacons in fixed locations within a facility where they transmit advertising packets that are picked up by the user’s smartphone. The smartphone is then able to calculate its own location based on the RSSI of the packets received from the beacons and possibly place the calculated location on a map presented to the user.
In 2019, a new exciting feature called Bluetooth® direction finding was introduced in version 5.1 of the Bluetooth standard specification. This new feature allows Bluetooth Low Energy devices to increase the accuracy of the location of Bluetooth devices based on either the Angle of Departure (AoD), the Angle of Arrival (AoA), or both. As we mentioned earlier, the increased accuracy usually comes at a higher cost.
For the case of indoor navigation, AoD is the more suitable method usually implemented. In this method, the device to which direction is being determined, such as a locator beacon in an IPS solution, transmits a special signal using multiple antenna arranged in an array. The receiving device, such as a mobile phone in that same IPS solution, has a single antenna. As the multiple signals from the transmitting device cross the antenna in the receiving device, the receiving device takes IQ samples. Based on the IQ sample data, the receiving device can calculate the relative signal direction.
Ultra-Wideband is a short-range radio technology that’s popular in indoor navigation systems. UWB operates in the frequency range of 3.1 and 10.6 GHz and has a bandwidth of at least 500 MHz.
Indoor positioning systems that are UWB-based differ from Bluetooth® Low Energy beacon solutions in that they utilize Time-of-Flight instead of RSSI measurements to estimate distances that are then used in trilateration calculations to determine device location.
The basic principle behind the time-of-flight method is the ability to calculate the distance from one device to another by knowing both (1) the time it took for the signal to propagate from the transmitter to the receiver and (2) the signal velocity. Finally, these values are utilized in a trilateration calculation to figure out the position of the target device.
Here are a couple of the benefits of UWB indoor positioning systems:
- Higher accuracy than RSSI-based techniques used in other technologies, since they operate in a very broad band of frequencies – measuring the time-of-flight of any radio signal is correlated with its bandwidth
- Reduced interference with other signals due to the low transmit power and short transmit duration of the UWB signal
Some of the disadvantages include:
- High cost, sometimes even prohibitive
- The lack of wide adoption in smartphones and mainstream devices, which has the potential to affect usability and user experience of the system since the solution will require specialized UWB tags (or wristbands) to be worn by the users
- The lack of global standardization – regulations differ across different regions of the world
Another wireless technology utilized for indoor navigation systems is Wi-Fi. The main benefit of Wi-Fi is that its infrastructure exists almost everywhere you go. This would seem to make it an easy choice in many cases; however, it lacks some major drawbacks. Some of these are:
- Lower accuracy
- Limited (or non-existent) support on iOS devices compared to Android (in device-centric implementations)
- Requirement of specialized hardware which could lead to high deployment costs (in network-based implementations)
Solutions utilizing Wi-Fi do not necessarily require a connection to the locator nodes/access points, however, non-connection–based solutions have an impact on accuracy and latency times of the system. The two main parameters used in these systems are:
- The RSSI – used for approximate distance calculation
- The MAC address – used for device identification
RSSI measurements are used along with trilateration to determine an approximate location of a device within a space. Fingerprinting is another method that’s used to determine location using Wi-Fi. It utilizes historical RSSI information along with known locations to more accurately determine the location of the device.
Time of Flight (ToF) is another technique sometimes used in WiFi-based indoor navigation implementations. The basic concept takes timestamps provided by the wireless interfaces to calculate the ToF of signals and then use this information to estimate the distance and relative position of one client device with respect to access points. ToF requires a connection between the devices and the local Wi-Fi network which can compromise privacy and security, as well as present scalability issues.
Ultrasonic technologies use sound waves to transmit digital data in the frequency range above 20 kHz. In the case of indoor navigation systems, ultrasonic technologies are used for detecting the location of an object using Time-of-Flight (ToF) calculations. ToF, along with trilateration, is utilized to achieve object location detection accuracy within a few centimeters.
Unlike RF signals, ultrasonic signals are usually obstructed by walls and objects within a space. This can serve as an advantage in the case of indoor navigation since it can pinpoint a device’s presence within a specific room.
Ultrasonic indoor navigation systems require the deployment of locator devices within a facility in addition to tags that are attached to the users that need to navigate the space.
Now, let’s compare the most common technologies in terms of the key attributes we listed:
It’s important to keep in mind that for some indoor navigation applications it may be more suitable to utilize a combination of one or more of these technologies instead of using a single wireless technology.
In addition to utilizing RSSI, ToF, and other methodologies for determining location, an indoor navigation system could also utilize advanced software algorithms and sensor fusion (utilizing measurements from multiple sensors) to enhance the accuracy of positioning calculations.
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