Wireless Technology Used in Hazardous Areas

Often when we talk about wireless technology in the process industries, it is said in the context of the Industrial Internet of Things (IIoT) or industry 4.0.

As the digital transformation of process industries has evolved, the number of wireless devices being added has increased and forced companies to rethink their wireless network strategy.

There are several wireless technologies used for a whole variety of use cases associated with hazardous and harsh industrial environments typically seen throughout the process industries.

The fact is, deploying wireless in an industrial setting is not nearly as simple as deploying it in an office or factory environment. Heavy industrial environments pose unique challenges and conditions, including dense metallic infrastructure and hazardous environments such as potentially explosive atmospheres

Source: Market Research Report, 2020 – Markets and Markets

This article looks at some of the most common wireless technologies used and consider some of the pros and cons of each.

WiFi

Probably the most common and well-known wireless technology used globally. WiFi is a wireless network standard designed to allow mobile devices to communicate with each other or servers to access and exchange data using IP connectivity. WiFi operates in the ISM bands at 2.4GHz and the 5GHz band. With this technology being so mature there are a lot of hazardous area certified devices available compared with some of the newer wireless standards.

Cellular Network’s (3G, 4G, 5G and LTE)

Cellular networks are commonplace in everyday life providing wide area network connectivity and voice communications for mobile phones. More recently versions of the standards are available that allow IoT applications with the advent of NBIoT and LTE-M protocols. This then allows low cost, low power communications over long distances for battery powered sensors.

Some sites are now opting for private LTE networks. There has traditionally been two ways of providing this to customers by the Mobile Network Operators (MNO) that own the radio spectrum. The easiest option is to use the existing network infrastructure that is normally used for the general public. They offer a segregated part of the bandwidth on the closest cell tower to the site that is only available to that particular customer. This is often not a practical solution because the location of process plants is not usually in an area where the cellular coverage is good across the site. Another option is the MNO can install a dedicated cell tower/base station just for that site. This usually costs a lot more and will require the customer to commit to payment plans running into many years so that the MNO can get the return on the capital investment of the site-specific equipment.

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It is worth noting that complete site coverage is difficult to achieve with LTE networks inside the process areas due to the dense metallic infrastructure. The way to overcome this challenge is to install Pico Cells in hazardous area wireless enclosure systems in these locations to allow full site wide coverage to be achieved.

A recent development with LTE and 5G networks is the advent of private LTE/5G that can be deployed in much the same way as a WiFi network is by the end user, without the need to go to an MNO. In the USA this type of private LTE is called Citizens Band Radio Service (CBRS) and is also being made possible in other parts of the world. First conceived by the FCC in 2012 and launched in 2017, this new possibility is being made available in many countries around the world. Although gaining in popularity it is important to note that the free to access spectrum is different in most countries which will mean the number of mobile devices that are available will be limited for some time and especially hazardous area approved devices.

LTE/5G is acknowledged to provide a higher degree of security and deterministic latency compared to WiFi and has a much greater coverage. Typically, coverage outdoors is 10 x and indoors 4 x that of WiFi.

LoRaWAN®

LoRaWAN® is a low power, wide area network protocol used for wireless connectivity of devices to internet networks. It is designed as a low power, low bandwidth technology especially for battery powered sensors. It was originally available in the sub-GHz bands but more recently a new 2.4GHz version is being launched which has less range but much higher bandwidth. The new 2.4GHz band is in its infancy and is not part of the LoRaWAN alliance. As such there are few products available at the moment. Typical line of sight range for the sub-GHz band is over 10Km, which means only a few gateways are required to cover a large process plant.

WiHART/ISA100.11a

WiHART and ISA100.11a are two different protocols typically used for connection of battery powered sensors. Unlike LoRa it is much shorter range but running on 802.15.4 radio technology provides a higher degree of reliability as each device forms part of a self-healing MESH network. This wireless technology is almost exclusively used in battery powered process instrumentation devices.

Passive RFID

RFID tags are generally passive devices which when energized by a reader transmit their ID. They are typically used in asset tracking and identification applications and are available in three different frequency ranges: LF (125KHz), HF (13.5MHz) and UHF (900MHz).

UWB

Ultra-Wide Band (UWB) is a low energy radio technology for short-range, high-bandwidth communications over a wide range of frequencies. UWB is also capable of transmitting data at very high rates meaning it is well suited for short range high bandwidth wireless data transfer. UWB has more typically been used as a Real Time Location System (RTLS) solution for personnel and asset tracking in industrial settings because of its accuracy and low power consumption.

BLE

Bluetooth Low Energy (BLE) is a short-range wireless technology, although later iterations of the standard such as BLE 5 have a much longer-range capability of over 1Km in certain use cases. BLE operates in the 2.4 GHz ISM band and consumes very little power compared to traditional Bluetooth. BLE is typically used to tether devices together, location tracking or IoT connectivity.

Other Radio Technology

There are a lot of proprietary radio technologies on the market that use both the unlicensed and licensed spectrums. These include DECT for cordless phones, VHF/UHF walkie talkies, most commonly known as TETRA in the digital version, as well as long distance high bandwidth wireless links or short distance ultrahigh bandwidth wireless links that transmit in the tens of GHz range.

For more information or to see how Extronics can help you with your hazardous area wireless connectivity, please contact a member of our team on +44 (0)1606 738 446 or email us at info@extronics.com.