Choosing the right wireless technology is crucial for ensuring reliable, time-critical communication in industrial applications. In this blog, we summarize our experience with popular technologies like cellular, Wi-Fi, Sub-GHz, and IEEE 802.15.4 and highlight their strengths and limitations. We also explain why we use Bluetooth Low Energy (BLE) for replacing data cables in challenging industrial environments.

Over the last few years, we have successfully helped customers remove data cables from their industrial applications with our reliable Bluetooth communication. Using this approach, we have successfully replaced data cables, even in harsh environments with lots of external interference and moving metal objects blocking wireless communication. Here are our thoughts on why we use Bluetooth, specifically Bluetooth Low Energy (BLE), in these settings to achieve reliable, high-performance wireless communication in large-scale industrial applications.

When building industrial wireless networks, you can choose from many different wireless technologies. All of these have unique strengths and limitations; choosing the right wireless technology is critical for the reliability and performance of your industrial application. This post will delve into the most popular wireless technologies used in industrial applications and what we have learned from our customers about their advantages and downsides. Furthermore, we show why we use Bluetooth – specifically Bluetooth Low Energy (BLE) – to reliably exchange time- and safety-critical data in industrial warehouses.

Popular Wireless Technologies

Cellular Technologies

Cellular technologies like 4G, 5G, and Narrowband-IoT are often used for condition monitoring and predictive maintenance. These solutions enable easy integration and retrofitting of sensors to monitor industrial processes.

Advantages:

• These technologies support large communication distances, so it is easy to cover wide-area deployments.
• Most cellular technologies (e.g., 4G and 5G) support data rates above 150 Mbit/s, which allows the efficient exchange of large data chunks.
• Cellular technologies support a large number of devices in their networks.

Disadvantages:

• Cellular devices must connect to a nearby base station. Getting coverage from a public base station in industrial warehouses is often challenging.
• One way to ensure a high-quality and high-performance cellular network is to have a dedicated private cellular base station (e.g., 5G cell). However, these private base stations are expensive.
• Connecting to a cellular network usually comes with per-device licensing fees.
• Per default, cellular devices are connected to the public Internet, which requires significant effort to protect all devices against cyberattacks.

Cellular technologies have many benefits, but their reliance on public or private base stations is a drawback for many industrial applications.

Wi-Fi

Wi-Fi is the de facto standard for wireless networking in private and commercial environments. Its high data rates and ability to support many devices make it attractive for industrial use.

Advantages:

• Wi-Fi networks support high data rates of multiple 100s of Mbit/s.
• Wi-Fi supports a large number of network devices without any problems.

Disadvantages:

• Wi-Fi devices typically support only a short range of <50 meters indoors. Several access points are required to cover larger areas (e.g., industrial warehouses).
• Wi-Fi communication has non-deterministic latencies (up to 250 ms) due to its mandatory Clear Channel Assessment (CCA). This CCA mandates that a device check if the frequencies are free before sending a packet.

While suitable for large data transfers, Wi-Fi’s unpredictable latency and short communication range make it less ideal for exchanging time-critical data in industrial applications.

Sub-GHz Technologies

Sub-GHz technologies operate in unlicensed frequency bands below 1 GHz (such as 433 MHz and 868 MHz in Europe). These technologies are typically used to exchange small data packets over long distances in industrial warehouses.

Advantages:

• Sub-GHz technologies have a long communication range (several hundred meters indoors) and can penetrate concrete and metal obstacles.

Disadvantages:

• These technologies have comparably high latencies of 60 – 70 ms on average, with peaks over 200 ms.
• Due to the lower frequency band, these technologies also support comparably low data rates of about 40–50 kbit/s.
• Due to the high latencies, Sub-GHz networks often have poor scalability, especially for bidirectional communication.

Sub-GHz technologies are great for covering large areas. However, their low data rates and high latencies make exchanging time-critical messages and longer data packets difficult.

IEEE 802.15.4

IEEE 802.15.4 is a well-established wireless standard and is the basis of protocols like ZigBee, WirelessHART, TSCH, and Thread. It operates in the 2.4 GHz band and offers flexibility for custom implementations and optimizations.

Advantages:

• The different protocols on top of IEEE 802.15.4 allow flexible configuration for specific use cases.
• IEEE 802.15.4 allows for optimizations to fine-tune the network to application needs specifically.

Disadvantages:

• Compatibility between different implementations of IEEE 802.15.4-based protocols is not guaranteed, which may sometimes lead to interoperability issues between devices from different manufacturers.
• By default, many IEEE 802.15.4-based protocols use only a fixed channel for data exchange, which makes them unreliable in industrial applications.
• IEEE 802.15.4 supports relatively low data rates of up to 170 kbit/s.

Depending on the protocol used, IEEE 802.15.4-based communication can be a great fit for industrial applications. However, the drawbacks of most of these protocols are the low data rate and possible interoperability issues.

Why we use Bluetooth Low Energy (BLE)

We use Bluetooth Low Energy (BLE) for all our wireless networks in industrial applications, such as industrial warehouses or smart retail stores. With BLE, we can reliably exchange time- and safety-critical data packets, even in harsh environments with heavy interference.

Advantages:

• BLE supports data rates of up to 1400 kbit/s, which is faster than networks based on IEEE 802.15.4 and Sub-GHz.
• BLE supports a predictable latency below 15 ms, even under challenging conditions (e.g., heavy interference), making it suitable for real-time data exchanges.
• BLE is highly reliable and robust against interference due to its built-in adaptive frequency hopping.
• BLE supports a communication range of up to 100 m indoors and over 1000 m outdoors.
• BLE devices are interoperable by design. BLE devices from different manufacturers can seamlessly communicate with each other.
• BLE allows large-scale networks of up to 1000 BLE devices in the same network to communicate reliably.

BLE’s ability to combine speed, reliability, range, and scalability makes it a very suitable wireless technology for replacing data cables in industrial applications.

Conclusion

For us, Bluetooth Low Energy (BLE) stands out as a versatile, reliable, and cost-effective solution for modern industrial applications. Its balance of speed, low latency, and reliability make it our choice for reliably exchanging time—and safety-critical data in industrial environments.