Meeting smart factories’ evolving needs with wireless technology

Wi-Fi 6 Industrial Wireless Insights

• Smart factories need reliable and fast wireless networks to help manage and maintain the enormous amounts of data being collected from many touchpoints on the plant floor.
• Wi-Fi 6 emphasizes high efficiency for wireless networks to help deal with this data collection, helping to prevent major slowdowns or other issues that keep smart factories from being efficient.

Smart factories are tough environments for wireless communication technologies, but Wi-Fi technologies are evolving and are still useful in these advanced facilities.

When Wi-Fi was first deployed in connected factories, it had a simple task: getting a few devices to talk to each other. Today, the situation is completely different. If just a decade ago the smart factory was like an empty plaza, today it’s more like a bustling market. The venue is the same; the context, however, has changed radically. Like at a noisy market, the airwaves have become busy, and devices must go to great lengths to make themselves heard.

Wireless technologies have continued to evolve to meet the increasingly demanding needs of the markets they serve. Wi-Fi is no exception. Advancing factory digitalization and new use cases are driving up demands on Wi-Fi, which carries an estimated 45% of global IP traffic and 60% to 80% of wireless traffic.

How Wi-Fi technologies have evolved

Wi-Fi has come a long way since the days when it maxed out at 54 Mbps. In 2009, Wi-Fi 4, or IEEE 802.11n as it was formerly known, brought a huge jump in throughput, with the combination of the 5 GHz band introduced in IEEE 802.11a and higher data rates in both bands. Backward compatibility of Wi-Fi 4 access points with devices featuring legacy versions of the technology helped boost uptake of the technology.

In 2013, Wi-Fi 5, or IEEE 802.11ac, brought another jump in performance, topping out at 6.8 Gbps, with operation restricted to the 5 GHz band. Wi-Fi 6 has provided performance improvements and enhanced its capability to handle more traffic from a greater number of clients more efficiently, which is why it is also referred to as high efficiency wireless (HEW).

Several innovations are helping Wi-Fi 6  meet today’s demands for higher throughput (close to 10 Gbps), while also delivering long-range performance, low latency, minimal power demand, coexistence and fast handover.

Figure 1: Wi-Fi 6 can reach a greater number of clients at a higher speed than Wi-Fi 4 or Wi-Fi 5. Courtesy: u-blox

Manufacturing industry’s expectations for Wi-Fi

As each release of the Wi-Fi standard has improved performance, the technology has found its way into more sophisticated and demanding use cases. At the same time, it has continued to drive demand for further improvements in the standard to meet emerging wireless communication needs, which include those common to industrial deployments.

High availability is paramount in factory settings where downtime translates to lost revenues. In crowded RF environments, this includes robustness to interference from other devices, as well as high throughput, allowing to shorten transmission times and free up bandwidth after each communication. Ensuring scalability – the ability to connect additional clients to the network without having to add hotspots – is key as Wi-Fi offers network connectivity to a growing number of devices. Faster response times are essential for industrial automation systems used, for example, to orchestrate processes in complex production lines. As more moving devices – from robots to smart power tools – are connected to the network, seamless roaming is gaining in importance to avoid lengthy reconnection attempts when the device enters the range of a new access point. And to simplify operations and keep costs low, simple commissioning and maintenance are essential.

Five Wi-Fi 6 benefits

If Wi-Fi 4 delivered “high throughput,” and Wi-Fi 5 brought “very high throughput,” Wi-Fi 6, which was first released in 2018, has been about “high efficiency.” The jump from 6.8 to 9.6 Gbps may be less spectacular than some of the order-of-magnitude increases brought by previous releases. Where Wi-Fi 6 has more efficient utilization of available bandwidth, accommodating more clients per access point without degrading network performance.

The key to efficiently handling more clients are technological innovations such as:

1. Multi-user orthogonal frequency division multiple access (MU-OFDMA) is a technique used to slice and dice available bandwidth into resource units of varying sizes, giving access points the flexibility to simultaneously serve multiple clients with the required resources. MU-OFDMA increases the number of clients a fixed number of APs can handle four-fold.

2. Multi-user multiple input multiple output (MU-MIMO) lets access points direct unique data streams to multiple clients simultaneously, in the uplink and the downlink.

3. 1024 quadrature amplitude modulation (1024 QAM) makes it possible to encode more information into each symbol. Wi-Fi 6 can pack 10 bits into a symbol – 25% higher capacity than Wi-Fi 5, which used 256 QAM.

4. Basic service set (BSS) coloring helps ensure channels with different “color” will not interfere.

5. Target wake time (TWT) lets devices save batteries and increase power autonomy.

The same technologies that enable increased client densities also increase throughput: Instead of slicing up the bandwidth to serve multiple devices, MIMO can bundle bandwidth and make multiple streams available to one client.

By enabling the simultaneous transfer of data to and from multiple clients, MU-OFDMA helps reduce congestion – a common problem in dense networks – to ensure data is delivered with minimal latency.

Thanks to the TWT feature, access points can instruct devices to enter a low-power mode and with pre-scheduled wake-up times. The very long achievable sleep times can improve battery life, especially for wireless sensors that sporadically transmit data.

Figure 2: Chart showing Wi-Fi’s evolving speeds, data rate, frequency, bandwidth. Courtesy: u-blox

Tapping into the 6 GHz spectrum with Wi-Fi 6E

To overcome the main resource limitation, available spectrum, regulatory agencies such as the FCC have opened the 6 GHz band for unlicensed Wi-Fi communication, in some cases more than doubling the amount of spectrum previously available on the 2.4 and 5 GHz bands combined. Access points and end devices capable of using the 1200 MHz of new spectrum will be labeled Wi-Fi 6E.

Benefits of the 6 GHz band include proximity to the already widely-used 5 GHz band as well as an abundance of non-overlapping channels with a range of channel sizes. Because the new spectrum is still largely untapped, devices will not have to contend with legacy clients crowding the airwaves.

Five systems that benefit from Wi-Fi 6 in today’s smart factories

Wi-Fi has become a mainstay in smart factories and is often complemented by Bluetooth technology, as well as proprietary and non-proprietary cellular communication technologies. Wi-Fi 6 will strengthen its position thanks to five features in particular.

1. Industrial sensor networks.

Wirelessly-connected sensors have become widespread in industrial settings, used, for example, to monitor vibrations and temperature for predictive maintenance. Today, they often rely on power-optimized communication protocols such as Bluetooth low energy or IEEE 801.15.4.

Wi-Fi 6’s low power performance is enabled by allowing devices to go to sleep for prolonged periods using the TWT feature. Bringing down the power demand of Wi-Fi-enabled sensors increases their power autonomy, simplifying maintenance. At the same time, taking devices off the air reduces spectrum congestion.

2. Motion control.

Improvements in latency and quality of service provided by OFDMA make Wi-Fi 6 a promising wireless communication technology for control applications. At the same time, device configuration use cases will likely continue to benefit from the low power demand and ubiquity of Bluetooth.

3. Human-machine interfaces (HMIs).

The ability of Wi-Fi 6 access points to handle higher device densities while maintaining good throughput to each device combined with low latency make Wi-Fi 6 a promising technology capable of enabling simple tablet-based HMIs used to read out data from connected machines all the way to more advanced augmented reality HMIs.

4. Augmented reality (AR).

The natural progression of HMIs that use static or handheld graphical user interfaces (GUIs)) is augmented reality. Whether mediated using tablets or smart glasses, AR can overlay real-time information, documentation, or blueprints onto a tablet’s camera feed or, using smart glasses, right into the user’s field of view. AR also can let engineers schematically visualize the inner workings of their industrial machines and evaluate problems without having to interrupt production processes.

5. Mesh networks.

Mesh technology has diverse use cases in industrial settings, including enabling centralized control of smart lights across a facility and collecting data from distributed sensors for processing in the cloud. While Bluetooth continues to be the wireless technology of choice to relay data from node to node all the way to the gateway, Wi-Fi is better adapted for the final leg of the transmission from the gateway to the enterprise cloud. It remains to be seen whether Wi-Fi 6’s low power consumption succeeds in paving the way for more widespread adoption of Wi-Fi mesh solutions in the industrial space.

Figure 3: The smart factory depends on reliable wireless technology to gather data from condition monitoring, motion control, augmented reality (AR), industrial sensor networks and human-machine interfaces (HMIs). Courtesy: u-blox

Other Wi-Fi types for connected factories

While Wi-Fi 6 outperforms Wi-Fi 4 on almost any metric, many applications are well served with the older version of the technology. When this is the case, plant managers can draw benefits from Wi-Fi 4’s lower cost and simplified development.

As Wi-Fi 6 is settling in, efforts are underway to take performance up another notch with the release of Wi-Fi 7, expected sometime after 2024. According to the IEEE and Wi-Fi Alliance, who drive the development of Wi-Fi standards, Wi-Fi 7 will focus heavily on video performance, including deterministic latency, high reliability and quality of service (QoS). It also will offer three-times faster throughput (30 Gbps) thanks to wider channels (up to 320 MHz) and higher QAM modulation orders.

Wi-Fi meeting demands through innovation

As smart factories continue to gain momentum, they will continue to depend on a patchwork of complementary wireless communication technologies, drawing on Wi-Fi, Bluetooth, 4G LTE, 5G and others. Wi-Fi 6 features such as faster data rates, lower latencies, lower power consumption, increased network capacity and increased reach have the potential to expand the technology’s footprint in smart factories.

Pelle Svensson, market development manager, product center short range radio, u-blox. Edited by Chris Vavra, web content manager, Control Engineering, CFE Media and Technology, cvavra@cfemedia.com.

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Keywords: wireless, Wi-Fi 6

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