WI-FI Based Indoor Positioning Technology
Prelude
Most of us have undoubtedly encountered this situation before: you're inside a sizable building, such an underground parking garage, shopping mall, or event center, and your GPS is having problems finding you on the map.
This is typically brought on by the building's concrete walls reducing the quality of your GPS signal. Contextual information can be provided by your smartphone apps by using your location. You may discover a retailer, obtain travel directions, or get alerts about deals in your area with that information. GPS is responsible for these convenient functions, but it has to be exposed to the outdoors to function at its best. However, a weak GPS signal within big buildings may make it impossible for you to get this information.
Even when you're not outside, accurate indoor positioning systems (IPS) that rely on open sensors and user consent can nevertheless deliver some degree of location-based data. In situations where GPS and other satellite technologies are ineffective or fail completely, an IPS is a network of devices that is used to find people or items.
This can apply to underground spaces, parking garages, alleys, airports, and multistory buildings. Particularly in multi-story buildings, the accuracy of current IPS methods is subpar.
About Wi-Fi Indoor Positioning Systems
Wi-Fi positioning, sometimes referred to as indoor positioning or Wi-Fi-based localization, uses Wi-Fi signals to pinpoint a person's or device's location inside an indoor space. Wi-Fi-based wireless indoor positioning systems require access points (APs) or routers to be active in order to function. Data is relayed by each Wi-Fi access point to provide internet access. Wi-Fi positioning is able to determine a user's location by utilizing signals that are released by Wi-Fi routers.
How Does Wi-Fi Positioning Work?
Wireless receivers, such smartphones and tablets, are able to receive signals sent by Wi-Fi routers. A user's position can be ascertained by processing the metadata included in each transmission.
Wi-Fi metadata –
The router's unique ID, or MAC address
Strength of Received Signal (RSS)
Every Wi-Fi router has a different MAC address, and the RSS gives an approximate distance estimate from the device. A weak RSS would suggest the user is far from the Wi-Fi router, but a strong RSS would reveal the user is close to that Wi-Fi hotspot.
What Are Wi-Fi Trilateration and Wi-Fi Fingerprinting?
Trilateration and fingerprinting are the two primary methods for location using Wi-Fi MAC address and RSS.
Every Wi-Fi router's location is used for Wi-Fi trilateration. Then, using the RSS, it determines the distances between each visible Wi-Fi router and the user in order to determine the router's position.
Wi-Fi fingerprinting uses a big fingerprint map of each MAC address's RSS at different places instead of requiring knowledge of Wi-Fi network locations. It then compares the measured RSS to the fingerprint map in real-time to establish the position of the user.
Because fingerprinting is so environment-dependent, environmental adjustments must be made in order to update fingerprint data. Whether it's putting up walls or relocating a tiny piece of furniture. Angle of Arrival (AoA) and Time of Flight (ToF) can also be used to establish location in addition to RSS and fingerprinting.The AoA is the angle at which Wi-Fi signals arrive at the antenna. A multiple-input multiple-output (MIMO) antenna is used for estimation using area of view (AoA), which clusters antennas together to boost throughput and range. MIMO antenna systems are frequently found in business settings.
Indoor Positioning Technologies
Through the use of BLE sensors and beacons, Bluetooth Low Energy (BLE) technology can determine an object's or person's general location, providing continuous asset tracking with at least room-accurate location. Much more accurate localizations can be achieved with position calculation utilizing the Angle of Arrival (AoA), however the hardware and sensor infrastructure support expenses are significant. Because of their ease of use and lower costs, BLE and Beacons have become the go-to indoor location technologies.
WiFi-based systems communicate readings to several WiFi access points by using WiFi transmitters as tags. Information algorithms calculate the source's position based on those readings. Eventually, the location data is transferred to a cloud environment. Although they can be pricey, systems that use WiFi and "time difference of arrival" (TDOA) technology provide a rather high level of accuracy (within 3 to 5 meters).
UWB Ultra-Wideband (UWB) systems use three-dimensional positioning to attain extremely high accuracy. The extraordinarily wide UWB signal and its capacity to emit a very wide pulse over a GHz of spectrum allow for continuous, highly accurate asset tracking. In the past, UWB-based systems have produced the best accuracy. Because UWB tags have limited reading ranges, even with their low cost, each location needs at least three readers. Because of this, a UWB solution is substantially more costly than a BLE solution.
Benefits of a Wi-Fi Positioning System
Since most buildings already have Wi-Fi connection, Wi-Fi indoor positioning does not require extra hardware in contrast to other indoor location options like BLE beacons or RFID. Since almost all facilities currently have Wi-Fi infrastructure in place, basic locating capabilities can be obtained without further investment. It is expensive and time-consuming to manually deploy hardware solutions, particularly if you have several locations that need the feature.
Because of this, alternative technologies need a bigger investment of time and money to set up an environment that works well for indoor positioning. Scaling Wi-Fi-based indoor positioning systems requires little to no manual effort. For example, it is less expensive to employ Wi-Fi location in 25 warehouses as opposed to physically placing BLE beacons or RFID in 25 warehouses. Wi-Fi location offers instant-on capabilities, but depending on the needs of the use case, organizations can enhance the accuracy in a few different ways.
To increase the accuracy of the system's positioning, a straightforward survey that maps out every Wi-Fi access point in a building can be conducted. Businesses can install more Wi-Fi access points within their buildings to increase accuracy. Although there is a cost associated with this, the customer does not have to install, train staff on, and maintain yet another piece of infrastructure equipment. This can be done by installing extra Wi-Fi access points in locations that need more positional accuracy, or it can be done as part of a larger effort to upgrade the Wi-Fi infrastructure.
Disadvantages of a Wi-Fi Positioning System
The precision of Wi-Fi positioning is the main drawback of a Wi-Fi positioning system. It might not be as appropriate for precise location applications as Bluetooth, with its 2-4m precision, given its accuracy at the higher end of 15 meters. However, using fingerprinting, a large number of Wi-Fi access points, and/or combining tracking data with other technologies (also known as sensor fusion) can reduce accuracy to as low as 2-3 meters. The most precise hardware-free indoor positioning solution available today was created by Mapsted and does not require the usage of external sensors.
A Wi-Fi positioning system's potential for security lapses is another drawback. Due to its widespread use, Wi-Fi has already seen multiple attacks and the ensuing security updates. Wi-Fi security will always be a worry, but businesses will always be trying to fortify Wi-Fi against malevolent attacks.
The accuracy of WiFi is one of its main drawbacks. It could not be as useful for precise location applications as Bluetooth, with its 2-4m precision, because of its upper end of 15m accuracy. With fingerprinting, a large number of WiFi access points, and/or merging tracking data with other technologies (sensor fusion), accuracy can be as low as 2-3 meters. Working with Intel, Oregon State University is developing SAIL, a WiFi indoor monitoring system that "achieves a location accuracy better than 1m." WiFi security will always be an issue, but businesses will always be trying to fortify WiFi against malevolent attacks. Indoor positioning systems (IPS) & Indoor location-based services (ILBS)
One of the main components that make the Industry 4.0 and Industry 5.0 paradigms possible for the realization of dynamic, sustainable, and adaptive manufacturing is cyber-physical systems, or CPSs. Real-world physical phenomena and relevant cyber representations of those phenomena are linked in multiple directions by true CPSs, which gather and process data from smart devices and the Industrial Internet of Things (IIoT). In contrast, "digital shadows" do not communicate with the physical system; instead, they merely facilitate the representation of data within the cyber-based twin.
For context-aware applications, such asset routing and security, a Cyber Physical System's (CPS) precise position data is essential. This is especially important when there are mobile users of the Industrial Internet of Things (IIoT) and their pathways and locations are not fixed. Apart from the advantages for the industry, customers want increased visibility of their assets while they are in transit, and authorities need assurances regarding the environmental integrity of assets, particularly in the fresh food, pharmaceutical, and medical sectors. Additionally, reliable location data is necessary to present users with contextually relevant services and information, encouraging acceptable behavior and well-informed decision-making.
Various methods have been discovered to approximate a position by utilizing the information gathered from every technology. These methods include radio mapping with received signal strength fingerprinting, proximity estimation using BLE beacons and binary sensors, and analytical algorithms with random forest machine learning and k-means clustering. Passive UHF RFID tags can also be employed for RSS fingerprinting. Every method has benefits and drawbacks of its own.
The ability to track people or vehicles inside a plant is the primary use of indoor location for industrial applications, particularly where there is a need for high precision and conditions that are primarily line of sight.
The limitations of vision-based indoor positioning systems include the necessity for distinctive and distinguishing features in the surroundings, line of sight (LoS), and a database of high-resolution photographs of reference items. These systems also don't require any prior map or location information; instead, as features are viewed and repeated over time, they gradually accumulate a map and become more accurate at estimating location.
Research comparing and analyzing IPS systems has to be more rigorous in order to help the deployment and choice of IPS systems more effectively.
Trends on Indoor Localization
When compared to vision-based interior localization, wireless technologies-based localization offers a more straightforward, affordable, and precise localization solution. Nevertheless, not every situation can be fully satisfied by the wireless technology and mathematical methods used today. There have been attempts in recent literature to decrease power usage, increase coverage, and improve precision. Four recent trends in wireless technology for indoor localization have been compiled below.
Combine Multiple Wireless Technologies
The protocols and bands used by various wireless technologies vary, as do their costs and power consumption during propagation. Wireless technology may also include unique features. Many advantages arise when two wireless technologies are combined. When two wireless technologies are employed, one is short range (like RFID and Bluetooth) and the other is long range (like WiFi and Zigbee). A localization system can cover a significant portion of the building with a small number of stations thanks to long-range technology's ability to give good building coverage. On the other hand, short-range technologies can be employed to further improve accuracy in crucial areas.
Adopt Multiple Mathematical Techniques
In spite of all the benefits, integrating several wireless technologies may nevertheless result in a significant rise in the overall system cost. Different wireless chips in the user device and beacon kinds are required. According to some studies, utilizing a variety of mathematical strategies can help increase localization accuracy. There could be a variety of cause mistakes in the data gathered from the received signal. The dependability of the signal source can be increased by combining several signal qualities. For example, both RSS and AoA of signal are gathered in literature [Elnahrawy05]. The distance between a user and a station is inferred using the RSS. In order to determine which option is most likely, the author constructs a Bayesian network by combining the outcomes of both measurements.
Involve Accelerometer and Other Technologies
Additionally, it's becoming more common for indoor localization systems to work in tandem with other wireless technologies, such as accelerometers and ultrasounds. Fingerprint technology can be used with infrared or ultrasound technologies. a hybrid radio-map that combines ultrasonic ToA with WiFi signal RSS. The outcome of the simulation demonstrates how resilient the hybrid system is against RSS noise. Another technique that works with wireless technology is dead-recking, which generates the user's traveling path based on movement data gathered from an accelerometer and compass. It can be applied to enhance or confirm mobile localization accuracy. To acquire the next position, the moving path and prior position are combined. The localization update interval may be shortened by the moving data as well.
Way Forward
Mobile phones are being used as localization devices in an increasing amount of literature. In the global scale, nearly every person possesses a mobile phone, indicating a high rate of market penetration for these devices. In the US, however, the penetration rate of smartphones reaches 64%. Typically, a smart phone makes use of several wireless technologies, including Bluetooth, RFID, and WiFi. Additionally, it's simple to design user applications and make use of the phone's resources using today's smart phone operating systems. Utilizing mobile devices for localization can reduce the amount of user devices needed and facilitate the widespread adoption of the localization system.
The market for localization-based services is growing. In addition to having a positive economic impact, localization services in indoor environments can enhance the quality of life for those with disabilities and perhaps save lives in emergency situations. Every wireless technology has advantages and disadvantages of its own. Additionally, they can employ the same or different mathematical procedures to accomplish high accuracy, high precision localization depending on the features of the wireless technology. numerous wireless technologies and numerous mathematical methodologies are merged to enhance the indoor localization performance. More options for indoor localization have arisen with the introduction of smartphones. The utilization of mobile phones for localization can simplify the deployment process and make it easier to implement.
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