UWB VS Bluetooth: Which Offers Better Indoor Positioning Accuracy

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We have well and truly entered the era of indoor positioning – whether it’s through asset tracking systems, location-based services or advanced navigation tools, indoor positioning is revolutionizing how we interact with enclosed spaces. The demand for accurate indoor positioning is only set to intensify – Markets and Markets projects the indoor positioning market to reach $31.4 billion by 2029! But implementation success hinges on choosing the right technology – the reliability of any indoor positioning system is only as good as its underlying tracking method. In this article, we compare two leading contenders in the space – Ultra-Wideband (UWB) and Bluetooth Low Energy (BLE) – to help you determine which technology best suits your indoor positioning needs.

Available indoor positioning technologies today

When out and about, we often rely on GPS to find our way around. It picks up signals from satellites orbiting Earth and achieves roughly a 5 – 20 meter level of accuracy. However, GPS has its limitations – once we step inside a building or head underground, those satellite signals get distorted. As a result, GPS becomes much less accurate indoors.

This is where Bluetooth and Wi-Fi positioning systems step in. These technologies based on received signal strength can help us locate objects and people within a few meters, making them suitable for basic indoor navigation. But technology is moving forward – new technologies like UWB and Bluetooth 5.1 aim to deliver even higher sub-meter accuracy down to just a few centimeters. This unlocks highly precise indoor applications for interaction with various actors in the environment like hands-free access control, asset tracking, and much more.

What is UWB and how it provides location

UWB is a short-range wireless technology that operates through low-powered radio frequencies. It operates within at least 500 MHz bandwidth, from 3.1 to 10.6 GHz. You might wonder if this range interferes with other technologies. Actually, no. Here’s why: UWB transmits data through nanosecond pulses without a carrier wave, using incredibly low power levels – just -41.3 dBm/MHz. In recent years, the IEEE 802.15.4z amendment has improved the MAC and PHY layers for ranging and localization purposes.

UWB mainly offers four methods to position objects and people:

  • ToA (Time of Arrival)
  • TDoA (Time Difference of Arrival)
  • TWR (Two-Way Ranging)
  • AoA (Angle of Arrival)

It’s worth noting that most companies choosing UWB for asset tracking prefer TDoA because of its low power consumption, which extends tag battery life.

UWB TDoA vs ToA vs TWR vs AoA

The TDoA technique is very similar to ToA, as both rely on measuring signal propagation time. However, TDoA has a clever advantage: it only needs receiver time synchronization, not absolute timing. In TDoA, tags broadcast signals to anchors, which relay the data to a central server. The positioning engine at the server then calculates the time differences of arrival to determine the tag’s location, achieving an accuracy of 10 to 30 centimeters. To perform this calculation, the server needs timestamps from a minimum of four anchors.

TWR works different, relying on individual tag-anchor ranging, but it’s more complex – requiring nine travel back and forth messages for a single position calculation. As for AoA? Well, it’s pricier and less accurate, and it’s not the popular go-to choice in UWB positioning.

How does Bluetooth enable location

Bluetooth is a frequency-hopping radio technology transmitting data in packet, which operates in the 2.4 GHz band. There are two main categories: Classic Bluetooth (versions 1.0-3.0) and Bluetooth Low Energy (BLE, version 4.0 and later). The key difference? Power consumption! BLE is specifically designed for low power consumption applications.

Bluetooth RSSI vs Bluetooth AoA/AoD

Prior to Bluetooth 5.1, BLE was widely used for indoor positioning using RSSI (Received Signal Strength Indicator) to measure path loss and estimate distances between transmitters and receivers. However, traditional BLE asset tracking was more about proximity than precise location – if you wanted better accuracy, you had to deploy more beacons into the area.

In 2019, the Bluetooth SIG updated the 5.1 core specification with enhanced direction-finding capabilities. This specification enables asset tracking using Angle of Arrival (AoA) or Angle of Departure (AoD) by utilizing antenna arrays to determine signal direction, achieving positioning accuracy within 1 meter. AoA requires multiple antennas at the receiver, while AoD needs implementation at the transmitter.

Currently, most commercial implementations still rely on RSSI due to its simplicity and widespread hardware support. However, Bluetooth AoA is creating quite a buzz in the positioning market by combining BLE’s cost-effectiveness with UWB-level precision. MOKO SMART has already launched tags and gateways that support this high-precision Bluetooth AoA positioning.

At the time of this writing, Bluetooth 6.0 has been released, with a focus on Bluetooth Channel Sounding. It uses phase-based ranging (PBR) and round-trip time (RTT) for secure and fine ranging between devices. More distance awareness applications are waiting for us to explore!

Comparison of UWB vs Bluetooth positioning

We’re witnessing some exciting battles in indoor positioning technologies. UWB and Bluetooth are both making waves, but they each bring something unique. Let’s zoom in on UWB and Bluetooth AoA to compare them against each other.

Precision and Coverage

UWB has a clear advantage in positioning accuracy, achieving centimeter-level precision (typically 10-30 cm) due to its ultra-wideband characteristics, which is hard to match with other narrowband systems. In addition, UWB signals can pass through obstacles, such as walls/floors, and machines, and are therefore ideal for complex industrial environments.

Theoretically, UWB can cover up to 200 meters. In large, open spaces, you will require fewer devices to cover the same area. In contrast, Bluetooth AOA has a smaller coverage range and is significantly affected by installation height.

Want to see these solutions in action? We’ve deployed both Bluetooth AOA and UWB positioning systems at the MOKO factory – reach out to us for a demo video!

Interference Resistance

At the same data transmission rate, UWB outperforms Bluetooth in interference resistance. The 2.4 GHz frequency band used by Bluetooth is getting pretty crowded, with interference from various devices and networks. UWB, however, leverages its higher frequency band and unique signal characteristics to maintain rock-solid performance even in complex wireless environments.

Power Consumption

In comparison of minimum average power consumption, BLE typically takes the win, consuming less power than UWB. But here’s the interesting part – in real-world applications, the difference might not be as dramatic due to the operational mode of tags! In BLE AOA or UWB cloud computing mode, tags spend most of their time in sleep mode, only waking up to transmit signals while the network handles positioning calculations. Their life can last up to 1-2 years. If using a device-side computing mode, where tags must stay awake longer, their lifespan may drastically reduce to just a few weeks or days.

Deployment Challenges

Practically, it is usually easier to implement UWB TDoA. Its time-based algorithms are relatively simple, while Bluetooth AOA systems need multiple calibration points – time, angle, and anchor positions all need to be just right.

Moreover, UWB maintains high accuracy across various environments, including complex building structures. But for Bluetooth AOA? It’s a bit more sensitive to environmental changes. Sometimes it requires extra calibration, or may require additional base stations to maintain optimal performance in some challenging spaces.

Cost and Scalability

Now we come to costs, Bluetooth AOA and UWB TDOA base stations are in a similar price range, but there’s a significant difference in tag costs. Bluetooth AOA tags are more budget-friendly than their UWB counterparts – a difference that really adds up in large-scale deployments. Bluetooth AOA’s cost-effective tags could save you substantial money if you plan to track numerous assets.

Comparison table of UWB vs BLE RSSI vs BLE AoA

BLE RSSI BLE AoA UWB
Standards/Protocol Bluetooth 4.0+ Bluetooth 5.1+ IEEE 802.15.4z
Typical Accuracy 2-5m 0.5-1m O.1-0.3m
Tag Power Consumption Low Low Medium
Connectivity Non-line-of-sight capable Line of sight to 3+ anchors needed Line of sight to 4 anchors needed
Interference Protection Poor Moderate (better than RSSI) Excellent
Ease of Installation Simple beacon placement Complex antenna array setup and calibration Standard anchor mounting with calibration
Scalability High (many devices supported) Medium Difficult
Tag Cost Low Low High
Infrastructure Costs Low ($) Medium ($$) High ($$$)

UWB or BLE: the choice for indoor positioning

Choosing the right indoor positioning solution isn’t a one-size-fits-all decision. We need to take various factors into consideration: the environment, system architecture, existing infrastructure, budget, and of course, the positioning precision. If you need high accuracy, UWB and BLE AoA are the way to go. If precision isn’t your top priority, Bluetooth RSSI positioning might be your best bet – it’s practical and cost-effective.

For high-precision positioning, the choice between Bluetooth AOA and UWB really comes down to your specific use case. If you’re tracking a limited number of high-value assets with extreme precision? UWB TDoA is probably your best bet. If you’re looking to track numerous assets with “pretty good” accuracy? Bluetooth AOA’s lower tag costs and decent precision might be the way to go. Don’t forget about system compatibility – Bluetooth positioning is more widely supported across various devices. However, UWB integration typically needs more specialized hardware and software.

Here at MOKO SMART, we’re all about getting you the IoT devices that fit your needs. Our product range includes various Bluetooth beacons, sensors, BLE AoA tags, alongside our UWB tags. We don’t just throw technology at you – we’ll help you figure out exactly what devices make sense for your specific situation.

Written by ——
YK Huang
YK Huang
YK is a seasoned Product Manager at MOKOSMART's R&D department with over a decade of smart device development experience. He is PMP and NPDP certified adding to his knowledge of how to navigate cross-functional teams. Having utilized data-driven insight to successfully launch more than 40 connected products. With a background in Electronics & Engineering, YK works well at transforming complex technical value propositions into user-friendly IoT solutions for both consumer and industrial applications.
YK Huang
YK Huang
YK is a seasoned Product Manager at MOKOSMART's R&D department with over a decade of smart device development experience. He is PMP and NPDP certified adding to his knowledge of how to navigate cross-functional teams. Having utilized data-driven insight to successfully launch more than 40 connected products. With a background in Electronics & Engineering, YK works well at transforming complex technical value propositions into user-friendly IoT solutions for both consumer and industrial applications.
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