The benefits of 5G in the factory

Progress towards the Fourth Industrial Revolution will rely heavily on wireless communications in the factory.

With the arrival of 5G technology, the manufacturing industry faces its biggest transformation yet. Safer, flexible and more efficient manufacturing systems will be possible due to the ultra-low-latency and reliability of 5G connectivity. This enables continued automation of robots and warehouse transportation as well as the cutting of cables for true flexibility.

Cut the wires

During the last 200 years we have seen tremendous development in industrial production. During this time there has been a shift away from craft production and towards mass production. Mass production was a result of a technology push to make manufacturing more productive.

With mass production we lost the ability to produce customised products. The customer need for customised products, however, is still there. For this reason there is a strong market pull to make industrial production far more flexible than it is today.

Flexible production, however, is not allowed to increase the cost of production. On the contrary there is a need to increase automation in order to maintain quality and stay competitive. In some regions competitiveness is the main driving force, while in others quality is the driving force.

During the last 30 years we have automated everything that can be automated in the factory using wired technology. The main processes that have so far not been automated are the integration of logistics, materials handling and factory automation.

The integration of logistics, materials handling and factory automation can only be achieved by using wireless technology. A vision of this is shown in Figure 1.

In this vision:

• A truck arriving with material for the factory announces its arrival to the factory and communicates directly with an AGV. The AGV unloads the truck and delivers the material to an assembly line.
• Assembly lines, machines and robots in the factory are connected wirelessly in order to maintain a high degree of flexibility.
• Workers are mobile and use wireless devices to monitor and control the factory.
• Finished products are placed in an automated warehouse before they are loaded onto a truck.

Figure 1: Vision of the future factory. Source: 5G-ACAI, 2021¹. For a larger image click here.

The introduction of wireless technologies in industrial production has already started. Today we see a multitude of wireless technologies being used for different use cases in industrial production.

Initially wireless technologies were used for select non-critical applications, but increasingly wireless technology is becoming the norm and is becoming more and more mission-critical.

None of the wireless technologies used today have the reliability, scalability and performance that are needed for tomorrow’s industrial production. But now, from a technical perspective, 5G cellular technology has the potential to meet all the requirements.

Table 1: Today’s use of wireless technologies in industrial production. For a larger image click here.

5G cellular networks

5G is the first cellular generation that specifically targets machine-to-machine communications. The different services are illustrated in Figure 2.

Figure 2: 5G cellular network services. For a larger image click here.

Massive Machine-type Communication (eMTC) allows vast numbers of battery-operated, low-power devices to be connected. From an industrial production perspective this type of service will enable:

• Wireless sensor networks
• Location and asset tracking.
   

Ultra-Reliable Low Latency Communications (URLLC) allows latency below 1 ms on the radio interface as well as availability exceeding 5-nines (99.999%). From an industrial production perspective this type of service will enable:

• Motion control
• Mobile robots
• Human remote control
• Mobile control panels with safety functions.
   

Enhanced Mobile Broadband (eMBB) is primarily targeting residential internet access with speed and latency on a par with fibre optic networks. From an industrial production perspective this type of service is suitable for:

• AGVs
• Augmented reality
• Remote access
• Inbound and outbound logistics.
   

For the first time in the history of industrial production a single wireless technology offers the solution to all aspects of communications within the factory. The only area not suitable for 5G within industrial production is motion control with sub-millisecond cycle time requirements.

Frequency spectrum

5G is primarily intended for public networks in licensed bands, but it is also possible to use as a private network as a:

• Private network in an unlicensed band
• Private network in a licensed band (own radio licence or sublicensed from a cellular operator)
• Semi-private network using a slice of the public network.
   

For some factory owners it is important to own and control the communications infrastructure. In this case it is relevant to use either unlicensed frequencies or to get a licence to operate in a licensed band.

The advantage of using unlicensed spectrum is that it is easy to deploy without obtaining a licence first. The downside is the possibility of interference from other users in the area as well as limitations in transmit power.

In the case that the factory owner prefers to use licensed frequencies, a licence can be obtained from the government or alternatively sublicensed from a mobile operator.

Factory owners looking to outsource the operation of the factory 5G network can make an agreement with a public mobile operator to provide the service. The service level agreement will cover aspects such as availability, coverage, bandwidth, life cycle management etc.

Generally you get better coverage with lower frequencies. Lower frequencies, however, are also in high demand from mobile operators, broadcasters, emergency services and other users of the radio spectrum.

Licensed spectrum is available around 3.5 GHz as well as in the 26 GHz band in most countries. For unlicensed deployment of 5G the 5 GHz ISM band is a good candidate. In the 5 GHz ISM band 5G will be sharing the spectrum with WLAN.

5G for industrial automation

The main driver for 5G within industrial production is to automate the processes that today cannot be automated using wired technology. There is, however, also a need to migrate some of today’s PLC communications from industrial Ethernet to 5G. The driver for this is increased flexibility, increased reliability and reduced cost for some use cases.

5G PLC communications might only be a small fraction of the total traffic on the 5G factory network. It is, however, the most demanding due to requirements for real-time performance and reliability. For PLC communications, we need low latency and high availability. Low latency and high availability is already supported by the 5G new radio (NR) interface. Only in the case of motion control applications will 5G not be fast enough.

Table 2: Industrial Ethernet protocols and typically achievable cycle times. For a larger image click here.

Unfortunately most industrial Ethernet protocols do not rely on TCP/IP and have various extensions to the Ethernet standard in order to support low latency and high reliability. With today’s cellular standards only TCP/IP traffic is supported. This means that most of the industrial Ethernet protocols listed in Figure 6 will not be compatible with 5G. Only EtherNet/IP and Modbus/TCP will be supported on 5G directly.

In order to improve the support of industrial Ethernet, 3GPP is standardising Ethernet as a service on 5G. This standardisation also includes the support of time sensitive networks (TSN). At the same time most industrial Ethernet protocols are being updated in order to replace proprietary real-time extensions with TSN. This means that once this standardisation work is finalised it will be possible to more fully support industrial Ethernet on 5G networks.

In the meantime it is possible to deploy gateways that adapt the industrial Ethernet protocols to 5G. An example of this is shown in Figure 3.

In this example Ethernet is tunnelled over IP and the IP quality-of-service header field is marked depending on the real-time requirements of the underlying PROFINET traffic. On the cellular network the non-real-time traffic is carried using a default bearer. Real-time traffic on the other hand is carried on a dedicated bearer which provides a guaranteed bit rate and low latency. With this setup it is possible to support industrial Ethernet on 5G with cycle times down to a couple of milliseconds.

Figure 3: Tunnelling of industrial Ethernet on a cellular network. For a larger image click here.

Conclusion

Industrial production is undergoing its fourth revolution. The goal is to increase flexibility and at the same time increase automation. Ideally production in the factory should be handled completely without any manual tasks. Only in case of failures or other exceptional cases should humans need to intervene.

The Fourth Industrial Revolution can only succeed by relying heavily on wireless communications in the factory. From a technical perspective 5G is the technology that is best suited for the future factory.

^{1. 5G-ACAI 2021, 5G for Connected Industries and Automation, <<https://5g-acia.org/wp-content/uploads/2021/04/WP_5G_for_Connected_Industries_and_Automation_Download_19.03.19.pdf>>}

Top image: iStock.com/metamorworks