For many applications deployed in manufacturing networks, communication latency has been a significant barrier. Despite the constant development of improved communication protocols and standards during Industry 4.0, the latency problem persists, lowering quality of services (QoS) and quality of experience (QoE). Tactile internet (TI), with its high availability, security, and ultra-low latency, will add a new dimension to human-machine interaction (HMI) by enabling haptic and tactile sensations. The tactile internet (TI) is a cutting-edge technology that uses 5G and beyond (B5G) communications to enable real-time interaction of haptic data over the internet between tactile ends. This emerging TI technology is regarded as the next evolutionary step for the Internet of Things (IoT) and is expected to bring about massive changes towards Society 5.0 and to address complex issues in current society. To that end, the 5G mobile communication systems will support the TI at the wireless edge. As a result, TI can be used as a backbone for delay mitigation in conjunction with 5G networks, allowing for ultra-reliable low latency applications like Smart Manufacturing, virtual reality, and augmented reality. Consequently, the purpose of this paper is to present the current state of 5G and TI, as well as the challenges and future trends for 5G networks beyond 2021, as well as a conceptual framework for integrating 5G and TI into existing industrial case studies, with a focus on the design aspects and layers of TI, such as the master, network, and slave layers. Finally, the key publications focused on the key enabling technologies of TI are summarized and the beyond 5G era towards Society 5.0 based on cyber-physical systems is discussed.
1. Evolution of Network Technologies
Over the last decade, the manufacturing industry has been undergoing a digital transformation known as “Industry 4.0”. Cloud, artificial intelligence (AI) and machine learning, new connectivity technologies (5G, Wi-Fi 6, etc.), Internet of Things (IoT) and sensor technology, digital twins, and robotics are all contributing to the digitization of manufacturing
[1]. Most manufacturers strive to increase efficiency and productivity. Most businesses aim for a 3% increase in productivity year over year. Thus, operational equipment effectiveness (OEE) is an important performance metric that assesses the efficiency of a production line by weighing three factors to produce an overall score: availability, performance, and quality. Additionally, three important challenges that manufacturers are facing in the volatile global marketplace are summarized as follows:
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Global competition: as revenues from the traditional model of selling products are squeezed, manufacturers must find ways to become more efficient on a continuous basis in order to compete at lower prices or adopt new business models.
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New consumer trends: consumers are increasingly expecting “on-demand” products that are fully customizable, putting pressure on manufacturers to reduce cycle times and create unique products while maintaining efficiencies.
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Skills shortages in the workforce: the introduction of new technologies necessitates the acquisition of new skills, and the manufacturing industry is struggling to attract new talent, with an estimated 2.4 million unfilled positions (or 15% of the total workforce) in the US alone by 2028
[2].
Improving efficiency is the key to addressing the challenges. To that end, technology will be a key driver by enabling rapid digital transformation. Data can help make better decisions, but the real benefits will come from developing new business and operating models. The four pillar technologies that will help in driving efficiency are big data, analytics, connectivity and management
[3].
While most people agree that better use of data can lead to better decision-making, there are still barriers to overcome. Manufacturers, for example, are facing interoperability issues. By extension, this issue is caused by the lack of tools and methods for easily connecting machines, tools and plants, and, most importantly, to aggregate data across silos in a consistent manner. On the other hand, a new generation of mobile communications is realized approximately every ten (10) years, as is illustrated in
Figure 1. More details for the evolution of network technologies is listed hereafter
[4,5][4][5]:
Figure 1. Evolution of mobile network technologies.
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1G–voice call: the 1G mobile network was put into use in the early 1980s. It has voice communication and limited data transmission capabilities.
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2G–message passing: in the 1990s, the 2G mobile network improved voice quality, data security, and data capacity and provided limited data capabilities through the use of GSM (global system for mobile communications) standard circuit switching.
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3G–multimedia, text, internet: the first commercial 3G service was introduced in 2003, including mobile internet access, fixed wireless access, and video calling.
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4G–real-time data, car navigation, video sharing: 4G was launched in 2008, making full use of all IP networking and relying entirely on packet switching. Its data transmission speed is 10× compared with 3G network.
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5G–is the most recent generation of mobile technology, and it differs from previous generations in that it is not simply a speed increase over 4G. It is more flexible than previous generations of cellular technology because it is software-based. Customers will be able to use different characteristics of 5G tailored to meet the requirements of specific applications, rather than one network that fits all.
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6G–is the next generation of mobile technology also known as “Next G”, which is still under development. Currently, initiatives are starting to form and research projects are set up in an attempt to begin the design, development, and experimentation on the required network infrastructure to support this new mobile network generation. According to recent research
[6], China has already set up two working works. Similarly, Japan has also invested $2 billion (two billion US dollars) in order to support research activities for 6G. Europe has also approved the research of 6G under the Horizon 2020 plan. North America has also begun working on the initiative called “Next G”, mainly at a university level.
Users can share data on the go with their smart devices using mobile communication and the mobile internet (MI). MI has millions of connected smart devices and has revolutionized various industries such as logistics, education, healthcare, and transportation in order to maintain quality of service (QoS) and quality of experience (QoE) for diverse customers
[7]. It also enables device-to-device (D2D) communication and invented the term “Internet of Things” (IoT), which allows low-power devices and/or equipment to execute specific functions in the area in which they are installed
[8]. Mobile devices can share prime or vital information in situations when a millisecond delay could harm a human life via D2D communication. The current cellular network architecture is not adequate for such sensitive data sharing, which has a latency of more than 20 milliseconds, due to poor data rates and significant delays.
However, for most smart applications, this delay for D2D connections is excessively long. Similarly, the term “tactile internet” (TI) was coined in early 2014 to characterize the ability to monitor and, as a result, act over the internet
[9]. As a result, TI is expected to offer up several new opportunities and applications that will improve the quality of life and work. According to market research, the worldwide market might be worth up to $20 trillion, accounting for at least 20% of global GDP today
[10]. Even though the term Internet of Things was established in 1995 it has recently faced significant popularity. Moving on, the TI is considered to be the evolution of IoT. Hereinafter, the key characteristics of each internet era are summarized
[11]:
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Mobile internet: suited for static or streaming content, video with limited resolution, web browsing
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Internet of Things (IoT): machine-to-machine (M2M) communication, billions of interconnected smart devices, low rate, latency, secure and reliable
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Tactile internet: human-to-machine communication (H2M), ultra-low latency, ultra-high availability, end-to-end security
2. Vision of Tactile Internet
The International Telecommunication Union (ITU-R) initiated a program in early 2012 to establish “International Mobile Telecommunication (IMT) for 2020 and Beyond”, laying the way for 5G research activities around the world.
Figure 2 [12] illustrates the 5G Roadmap. The International Telecommunications Union (ITU) has a long history of producing radio interface standards for mobile communications. IMT-2000 and IMT-Advanced are part of the International Mobile Telecommunications (IMT) framework of standards, which encompasses 3G and 4G industry perspectives and will continue to evolve as 5G with IMT-2020. The ITU multi-stakeholder framework’s reliability ensures a positive outcome for the global telecommunications community.
Figure 2. 5G Roadmap of IMT 2020
[12].
The TI, according to one ITU-T Technology Watch Report
[13], has taken a quantum leap forward. Tactile and haptic sensations will be enabled by TI’s high availability and security, ultra-fast reaction times, and carrier-grade reliability, adding new dimensions to human-machine contact (HMI)
[14]. The 5G technology vision envisions 1000-fold increases in area capacity, 10 Gb/s peak data rates, and connections for at least 100 billion devices to achieve this goal. The main challenge of 5G wireless access and core network architectures is to enable new machine-centric use cases that are currently unsupported by cellular networks. Additionally, the TI is characterized by the following technological capabilities
[12]:
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Ultra-low latency; 1 ms and below latency (as in round-trip-time/round-trip delay)
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Ultra-high availability; 99.999% availability
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Ultra-secure end-to-end (E2E) communications
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Persistent very high bandwidth capability (>1 Gbps)
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Bandwidth: data rates of 100 MB/s on average
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Capacity: up to 1 million devices per square kilometer
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Reliability: 99.999% network reliability
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Mobility: Seamless transfer between radio nodes up to 500 km/h
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Battery Life: up to ten (10) years battery life for low power (IoT) devices
However, it has to be mentioned that the TI should be able to highlight the difference between humans and machines. This should be used in situations where there is a high demand for machines and little interference from humans. Machines should be used to supplement humans rather than to replace them
[15].
3. Challenges and Motivation-Existing Cellular Technologies Cannot Support Tactile Internet Yet
Tactile applications based on control communications can now be developed with 1 ms round-trip latency (RTL) and ultra-high reliability and availability (as envisioned for 5G). As such, for the global economy, the TI has the potential to be a game-changer.
Table 1 compares the industrial automation performance requirements for 5G. To that end, the purpose of this study is to look into how 5G can fuel Smart Manufacturing and TI by reviewing existing trends, difficulties, and future trends. There will also be a discussion of the potential ramifications for operators in terms of network infrastructure and commercial prospects. The rate 10× factor
[16] is fast increasing the data rate need in IoT.
Table 1. Comparison of peak data rate versus latency
[18][17].
Use Case |
|
Availability |
Cycle Time |
Payload Size |
Number of Devices |
Typical Service Area |
Motion control |
Printing machine |
>99.9999% |
<2 ms |
20 bytes |
100 |
100 m × 100 m × 30 m |
Machine tool |
>99.9999% |
<0.5 ms |
50 bytes |
~20 |
15 m × 15 m × 15 m |
Packaging machine |
>99.9999% |
<1 ms |
40 bytes |
~50 |
10 m × 5 m × 3 m |
Mobile robots |
Cooperative motion control |
>99.9999% |
1 ms |
40–250 bytes |
100 |
<1 km2 |
Video-operated remote control |
>99.9999% |
10–100 ms |
15–150 kbytes |
100 |
<1 km2 |
Mobile control panels with safety functions |
Assembly robots or milling machines |
>99.9999% |
4–8 ms |
40–250 bytes |
4 |
10 m × 10 m |
Mobile cranes |
>99.9999% |
12 ms |
40–250 bytes |
2 |
40 m × 60 m |
Process automation (process monitoring) |
>99.99% |
>50 ms |
Varies |
10,000 devices per km2 |
As already mentioned, the critical challenge is to achieve a tolerable RTT of 1 ms in order to facilitate TI-related services and applications. Nonetheless, there are numerous challenging solutions for reducing network RTT. As a result, another motivation of the paper is to adopt TI technology in order to incorporate technological advancements such as software defined networking (SDN), network function virtualization (NFV), network coding, physical MAC-layer protocols, and cloud networking technologies that promise to meet the needs of the TI
[17][18].
The present 4G network is incapable of handling such high data rates. In this context, 5G technology has the potential to lead IoT applications that require high data rates, such as smart cities, smart grids, smart healthcare, connected cars, and linked homes
[19]. By 2020, there will be more than 50 billion gadgets connected to the internet.
Issues and concerns with IoT-based smart home applications, such as latency and reliability, were highlighted by Alaa et al.
[20]. TI can be utilized to alleviate these difficulties because it has ultra-low latency and carrier-grade frequency. The problems of IoT will be addressed by a future technical development, a 5G-enabled TI. In addition, the following are the components of TI: (a) fixed internet
[8], (b) mobile internet
[21], (c) things internet
[22], and (d) tactile internet
[8].
The 5G technology will be integrated in a heterogeneous network infrastructure. Three major frequency bands have been made available for use of 5G in Europe. These three bands are 700 MHz, 3.6 GHz, and 26 GHz. Next, the CBRS (Citizens Broadband Radio Service) band, which operates at 3.5 GHz, was opened up for commercial use in the United States in January 2020. Wi-Fi networking is also getting a makeover, and this supplementary technology will contribute to the 5G ecosystem. Finally, the IEEE 802.11ax specification is referred to as Wi-Fi 6 by the Wi-Fi Alliance because it is the sixth generation of Wi-Fi. Similarly, following the ongoing standardization, a new IEEE P1918.X standard has been defined for the TI
[23,24][23][24]. IEEE P1918.X describes the TI’s architecture technology and assumptions, whereas IEEE P1918.X.1, IEEE P1918.X.2, and IEEE P1918.X.3 focus on codecs, AI, and MAC for the TI, respectively. Furthermore, significant effort has been expended to form a working group for low latency industrial IoT (IIoT) applications such as intelligent transportation systems, Industry 4.0, and Health 4.0
[25]. Finally,
Figure 3 presents verticals sectors’ capabilities and requirements spider charts
[26].
Figure 3. Verticals sectors’ capabilities and requirements spider charts
[26].
In an attempt to properly introduce the key concepts of this research work, a short glossary is compiled below in the form of a table (refer to Table 2). Consequently, this table can facilitate the readership to become more familiar with the concepts of mobile networks, 5G, tactile internet, and Industry 4.0.
Table 2. Glossary of Key Concepts.
Term |
Definition |
Source |
Internet of Things (IoT) |
IoT can be realized as a new form of network created by physical devices. In this type of network, the physical devices are called things. Each thing is embedded with sensing systems and associated software which enable the connection and data exchange with other things over the internet. |
[27] |
Tactile internet (IT) |
According to the International Telecommunication Union (ITU), TI can be realized as the next generation of internet network. This new generation of internet is based on the combination of ultra-low latency, extremely high network availability, reliability, and security. Ultimately, TI will enable the advanced human-machine interface (HMI), based on the interaction of humans with the new TI environment through human senses. |
[13,28][13][28] |
xG mobile network, x∈[1,6] |
This notation refers to the mobile network generations, encapsulating the corresponding communication protocols. Concretely, “G” refers to “generation”, whereas the numerical value refers to the number of the generation. For example, 5G refers to the fifth generation of mobile networks |
[29] |