BehrTech Blog

A New Approach to Indoor Localization in Large-Scale Environments

Data on the location of critical equipment and workers, provides powerful insights to optimize asset management and worker safety. Nevertheless, effective indoor localization, especially in large-scale environments, has been a bottleneck in available tracking solutions.

The Global Positioning System (GPS) and many other terms like Navstar, Glonass, Satellite Location and Position Tracking are buzzwords we hear every day.

GPS provides services like asset tracking, fleet tracking, family and even pet tracking that have become essential to our daily life. These services are constantly evolving. UBER is a great example using GPS as a key enabling technology for its innovative service offerings in over 500 cities now globally.

Unfortunately, despite all of its unique power and global availability, GPS is not feasible for indoor location tracking. This is because it doesn’t have the capability to receive satellite signals in indoor environments or provide location calculations independently when no signal is available.

So, what if you’re looking for a commercial-grade indoor asset tracking solution? What if you need to track medical equipment in a large hospital, locate a tool in a large warehouse, or keep an eye on mining workers when moving in underground mines where GPS is out of reach?

Several technologies exist for asset tracking and positioning in indoor locations. However, these solutions come with multiple challenges, especially when implemented in a large-scale environment.

Challenges of Existing Indoor Localization Solutions

1. Proximity-Based Indoor Asset Tracking

Asset tracking solutions that rely on RFID and BLE Low Energy (BLE) have been around for some time. These solutions incorporate RFID tags or BLE beacons attached to the devices and communicate their ID data to a nearby hard-wired receiver. As RFID and BLE are very limited in coverage, these systems require a high density of receivers/sensing equipment. This quickly inflates infrastructure costs, not to mention the significant hassle of wiring a receiver every few meters in large-scale facilities.

Wi-Fi beacons/tags are another option, but the Wi-Fi range is also very constrained. A single Wi-Fi Access Point or Router usually covers a small area of up to 400 sq ft only, depending on the precision level needed. Also, Wi-Fi-enabled tags are very power-hungry compared to BLE, which makes it impractical for tracking of small devices.

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Proximity-based Indoor Tracking

2. Trilateration-based Indoor Positioning Systems

Indoor Positioning Systems (IPS) using Wi-Fi or BLE and trilateration technologies are an alternative for indoor localization. These solutions analyze the Received Signal Strength Indicator (RSSI) of each signal to estimate the distance between a device and a Wi-Fi/BLE sensing equipment (RSSI is inversely proportional to distance). Trilateration algorithms are then applied to locate the device by coordinating its distance data from three or more sensing points.

There are generally two scenarios for IPS solutions using Wi-Fi or BLE. In the first scenario, a user device, often a mobile phone, picks up signals from multiple access points or beacons and transfer these signals to the trilateration server. This approach is often applied with people tracking and navigation where typically every user has a smartphone.

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Trilateration-based IPS Scenario 1 (BLE example)

In the second scenario, a Wi-Fi tag or BLE beacon sends signals to multiple hard-wired receivers, which then relay received signal strength values to the trilateration server for location calculation. This scenario is more relevant for asset tracking applications where you can’t equip every asset with a smartphone. However, similar to proximity-based tracking, the major challenge is the high concentration of hard-wired receivers is required, especially in large indoor facilities.

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Trilateration-based IPS Scenario 2 (BLE example)

Another major pitfall of all Wi-Fi/BLE-based IPS solutions is the labor-intensive and costly calibration process. Due to the random characteristics of indoor signal propagation, calibration is required in the initial installation to collect RSSI samples and build a radio map (i.e. fingerprint) of a given area. Given the short range of Wi-Fi and BLE, RSSI samples have to be gathered every few meters, which is a major undertaking in vast areas. Also, for worker safety applications in challenging environments like underground mines, Wi-Fi and BLE signals are very unreliable.

Could LPWAN Be the New Answer to Large-Scale Indoor Localization?

So, what type of solution offers a cost-effective, practical and easy to install indoor localization solution in large-scale, long-distance applications? The answer could be Low-Power Wide Area Networks (LPWAN).

Today, LPWAN technology is regarded as a key enabler of the Internet of Things (IoT). Whether tracking parts, people, or equipment, LPWAN is driving IoT advancements with no trade-offs in battery life or costs for improved range and much greater reliability.

Providing unprecedented, multi-kilometer range, LPWAN is potentially the only solution able to cover an entire factory, warehouse, hospital or a mine shaft. As such, LPWAN can potentially replace Wi-Fi and BLE for indoor positioning in geographically dispersed, challenging environments.

How can you build a robust, real-time Indoor Positioning System with a cutting-edge LPWAN technology? At its core, the solution architecture resembles the second scenario of WiFi/BLE-based IPS. There are two major components involved: LPWAN radio equipment delivering robust, wireless indoor connectivity and coverage, and a positioning server running trilateration algorithms.

LPWAN gateways pick up signals from a low-cost LPWAN transmitter attached to an asset or carried by a worker, and then relays the RSSI data to the positioning server. Thanks to much better range and penetration capability, an LPWAN-based IPS requires only a few gateways to cover an entire industrial plant or commercial building.

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LPWAN-based Indoor Localization Architecture

Indoor tracking solutions with LPWAN do not require every asset and worker to have an expensive, battery-hungry Internet-connected device like a smartphone or tablet. In particular, it can also work effectively even in a “calibration-free” mode, thereby eliminating the hassle of site survey or fingerprinting the environment. What’s more, since only a few gateways are needed, the expensive and complex wiring process can be minimized.

Compelling LPWAN-based IPS use cases include worker safety and theft prevention of critical assets in vast industrial and commercial facilities, where sub-meter precision is not required.

Wrapping Up

There are many different tracking solutions and technologies in the market today. However, when factoring in cost as well as ease of implementation and management, LPWAN could be the most viable option. Furthermore, some LPWAN solutions, including ours, work on the principle that the data is the sole property of the customer and should not leave the premises. This makes LPWAN even more attractive for industrial and commercial applications where security and data privacy are a top priority.

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