The wireless standards being deployed today include Wi-Fi, Bluetooth, Bluetooth Low-Energy, ZigBee and Near-Field Communication (NFC). Each has strengths and limitations, which tend to define how they are deployed.
Unsurprisingly, Wi-Fi is the most prevalent; not least because it can connect large numbers of devices on the same network and extend up to several tens of metres from each access point. Maximum data rate is 54Mbit/s for IEEE802.11g, 72Mbit/s up to a theoretical maximum of 600Mbit/s for IEEE802.11n, or from about 500Mbit/s to more than 1Gbit/s with IEEE802.11ac in the 5GHz band. Usage is not metered, access is usually free and setting up a private Wi-Fi network is easy. While a password is needed to join a secured Wi-Fi network, unsecured networks are vulnerable.
All data passes through the access point, which represents a potential single point of failure, and devices connected to the network cannot communicate with each other directly. Although the nominal data throughput is high, making Wi-Fi a strong option for data-intensive tasks such as sharing large files or multimedia content, the effective throughput depends on the number of connected devices. Also, high power consumption means Wi-Fi is not ideal for energy-constrained battery-powered devices, particularly when small quantities of data are to be exchanged.
Two short-range wireless technologies stand out: ZigBee and Bluetooth. ZigBee has seen uptake in the industrial arena, not least because of its low cost and ability to deliver ‘mesh’ or many-to-many (m:m) communications. However, evolution of the more ubiquitous Bluetooth standard – including the ability to support mesh implementations – means Bluetooth and, in particular, Bluetooth Low Energy (BLE) are gaining favour. Among the benefits claimed are superior data rates and coding efficiency, the ability to implement lower power solutions, and enhanced resilience in ‘noisy’ RF environments.
Bluetooth mesh and beacons
Bluetooth, with a wireless range of about 10m, is designed to enable direct point-to-point communication between devices or point-to-multipoint links. However, data speed is limited to 1Mbit/s and devices must be paired. Exchanging data over Bluetooth demands less power than Wi-Fi, while BLE – designed for connecting small devices such as IoT endpoints – has even lower power consumption and longer range.
Bluetooth Mesh is an m:m capability optimised for large-scale device networks. According to the Bluetooth SIG, factory automation represents a major opportunity for wireless mesh networking as it can provide industrial-grade solutions that address the key issues of reliability, scalability and security. Reliability stems from the fact that mesh networks are inherently self-healing and do not have single points of failure, while scalability is assured as thousands of nodes can be supported with industrial-level performance. Mesh networks can also provide industrial-grade security against all known attacks.
“The world of Industry 4.0 – enabled by the industrial IoT – will require secure and reliable transfer of data in industrial workspaces.”
Bluetooth mesh networks can extend effective communication range and address the challenge of communication through physical barriers, while keeping power consumption low at individual device nodes. Previously, high-powered transmissions were the primary technique used to address issues such as radio interference in a factory environment or the transmission of signals through barriers such as thick concrete walls. This approach had severe limitations and has proven ineffective for power-constrained battery operated devices, as well as unfriendly RF environments.
By providing support for the new Bluetooth Mesh standard, BLE products can relay messages privately and securely via a mesh network, rather than requiring point-to-point connection. This increases the range and reliability of BLE communication without increasing power requirements.
Bluetooth also holds the key to ‘beacons’; another wireless communication solution being deployed in industrial environments.
Bluetooth beacons leverage the low power consumption and worldwide ubiquity of BLE to operate autonomously for long periods, broadcasting small amounts of information to mobile devices or other beacons in close proximity. Typically, the message payload is very small, enough to share a URL or location. A Bluetooth beacon can be placed almost anywhere, and broadcast its presence and identity to nearby Bluetooth devices. Data can be included in the transmission, which can allow the receiving device – typically a smartphone or tablet – to respond in various ways.
Beacon technology is likely to be employed in a number of ways in factory automation and industrial settings. Autonomous vehicles, for example, can move through factories by following beacon signals, eliminating reliance on expensive tracks or on-board vision sensors and complex guidance software. A beacon attached to expensive assets allows those items to be found within a range of up to 100m using a mobile phone app, or can be the basis for sounding an alarm if the distance exceeds a pre-set threshold. In warehousing and logistics, beacons can be attached to stock items or packages on a delivery truck, allowing staff to identify each one individually using a mobile device.
NFC, which uses technologies originally developed for RFID systems, operates in the 13.56MHz band. Communication range is only a few centimetres and the reading device responds only to the card in proximity for the duration it is within range. Since no pairing is needed, links can be set up quickly.
Further advantages in terms of delivering the security demanded in industrial environments can be realised when NFC and Bluetooth are used in concert: out of band pairing, for instance, uses NFC’s inherent security to establish the initial connection and Bluetooth’s open, low-power communications to support data transfer. This avoids the potential for ‘man-in-the-middle’ eavesdropping and devices connecting without permission.
Implementing industrial wireless designs
Whether Wi-Fi, Bluetooth, NFC or a combination of protocols, industrial wireless communication can deliver a number of benefits. Establishing connections between moving parts, for example, is easier without cables, while communicating through barriers such as walls or observation windows is simpler. At the same time, the sheer volume of nodes that need to communicate in future Industry 4.0 architectures makes cabling each device more and more impractical.
TOSHIBA ELECTRONICS EUROPE
Formed in 1973, TEE has headquarters in Düsseldorf, with branch offices in Germany, France, Italy, Spain, Sweden and the UK.