# Leveraging Asean Factori 4.0 Project Platforms and NB-IoT Cellular Communications for Research and Development Activities

Emil Novakov, Jean-Marc Thiriet

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Emil Novakov, Jean-Marc Thiriet. Leveraging Asean Factori 4.0 Project Platforms and NB-IoT Cellular Communications for Research and Development Activities. ECTI DAMT & NCON 2023, 6th ECTI Northern Section Conference on Electrical, Electronics, Computer and Telecommunications Engineering (NCON), IEEE Thailand Section, Mar 2023, Phuket, Thailand. hal-04734889

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# Leveraging Asean Factori 4.0 Project Platforms and NB-IoT Cellular Communications for Research and Development Activities

Emil Novakov

IMEP-LAHC

University Grenoble Alpes

Grenoble, France

emil.novakov@univ-grenoble-alpes.fr

Jean-Marc Thiriet

GIPSA-Lab

University Grenoble Alpes

Grenoble, France

jean-marc.thiriet@univ-grenoble-alpes.fr

**Abstract**— The European project Asean Factori 4.0 aims to develop the teaching of modern automation technologies as part of the Industry 4.0 concept. This paper proposes to use the automation hardware platforms developed in the project framework for research and development purposes. In particular, it proposes to use cellular radio frequency communication technologies to exchange data between the PLC and the sensors and actuators system. It shows that NB IoT technologies are suitable for this type of application and in particular for low energy consumption. It introduces the concept of a virtual PLC as well.

**Keywords**—PLC, RF, NB IoT, Internet, virtual PLC, 4G, cellular network, Asean Factori 4.0 Project

## I. INTRODUCTION

The European Erasmus+ Asean-Factori 4.0 project brings together European (France and Bulgaria) and Southeast Asian (Thailand, Laos and Cambodia) universities to develop the teaching of modern automation technologies, part of Industry 4.0 mainstream or the Fourth Industrial Revolution [1, 2]. The technologies taught are mainly related to the networking of industrial process control systems (Programmable Logic Controllers - PLCs) and the management of their IT security. This project defines new teaching curricula in the field of automation and cybersecurity. It also develops advanced automation hardware platforms for practical and Lab work. The project targets a broad user population that can be grouped into four categories:

1. students at bachelor and master level

2. companies and their specialists working in the field of industrial automation

3. teachers or trainers in industrial automation

4. decision-makers in university or company administrations.

At the beginning of 2023 three automation platforms are being developed and installed at the partners in South Asia. The main purpose of these platforms is the teaching of automation. A typical platform based on the Siemens Simatic S7-1500 PLC is represented on Fig.1. However, because of the modern hardware (PLC) used and the way they are structured, they can also be used for scientific and technological research (R&D).

This paper aims to show how this hardware can get used for scientific purposes. As the field of research and R&D possibilities (PLC programming, networking and communication protocols, computer security, real time problems, hardware and system aspects...) is extremely wide, we will focus on the introduction of Radio Frequency (RF) communication into PLC systems and in particular cellular

Narrow Band Internet of Things (NB-IoT) RF communication.

<figure><img src="image_1.png" /><figcaption>**Fig. 1** PLC platform installed in the Mae Fah Luang University (Chiang Rai, Thailand)</figcaption></figure>

## II. PLC USE CASES

The basic diagram of a standard PLC-based automation system is shown in Figure 2.a. The sensors and actuators (input system - I/O) of the production line or automated system are connected to the PLC via wire connections. The automate executes the control software. Modern PLCs are connected to the Internet and can be configured or exchange data via a network.

For some applications it is possible to replace the wire links of the I/O system with radio links - Fig.2. b. Two different groups of radio technologies can be used. The first group is based on proprietary RF communication systems that make use of unlicensed radio frequency bands. The most common standards are WiFi, Bluetooth, ZigBee, LoRa, Zeta. One of the project platforms is based on the configuration shown in Fig. 2.b and uses LoRa RF links for the sensors. It is also possible to use radio circuits based on classical RF modulation techniques (FSK, PSK, spread spectrum, ...) that are widely available on the market. All these techniques provide low power radio links. The main problem is the use of unlicensed frequency bands that are not protected against disturbances, interference or jamming. As a result, the reliability of the radio link is not guaranteed.

The second group is based on cellular networks. These networks use licensed frequency bands managed by a telecommunication provider. Cellular networks provide worldwide coverage and direct access to the Internet. Moreover, with the 4th and 5th generation (4G, 5G) all network
use standardized technology with multi-sources hardware and software suppliers.

<figure><img src="image_2.png" /><figcaption>Fig. 2.a Standard PLC configuration</figcaption></figure>

<figure><img src="image_3.png" /><figcaption>Fig. 2.b Wireless Input-Output configuration</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>Fig. 2.c Cellular wireless I/O configuration</figcaption></figure>

Fig. 2 Different configuration of the Input-Output system, the PCL and the Network Systems

The most widely used cellular data exchange system today is based on the General Packet Radio Services (GPRS) access mode of the second generation (2G) networks. Recently, two new standards have been introduced in the context of 4G and 5G networks: LTE-M and NB IoT. The advantage of this type of communication is threefold. They are ubiquitously adopted; they use protected licensed frequency bands and they provide high reliability of the radio link. Indeed, the RF data link (transmitter) can be managed by several base stations. In case of interferences or bad RF path quality the transmitter can be switched (handover) to another base station this providing a very high stability of the radio link. NB-IoT is designed specifically for use in the Internet of Things (IoT). This is the standard we believe is most suitable for use in automation. LTE-M is more oriented to automotive applications and can handle higher data rates.

The diagram of a PLC system based on NB-IoT technology is shown in Figure 2.c. There is no direct physical connection between the I/O system and the PLC. Data are transferred through the telecom's operator network providing

the service. Mixed wired and cellular configurations are also possible (a mix between Fig.2.a and Fig.2.c).

The use of NB-IoT raises two main issues - energy consumption and the speed of data transfer through the operator's network (delay trip). When using remote sensors and actuators, it is possible that some of them are battery powered. In this case it is necessary to use low power RF transmission systems. As the data is transferred through the operator's network as well as the Internet network it is necessary to be able to assess the delay in transfer and ensure that this delay is acceptable for the application. A study was carried out to address these issues. The results are presented below.

In Thailand NB-IoT services are provided by AIS Operator.

### III. NARROW-BAND INTERNET OF THINGS (NB-IOT) AND PLC

Narrow-band Internet of Things (NB-IoT) is a cellular radio technology standard dedicated to IoT applications. NB-IoT is specified in the Release 13 of the 4th generation Long Term Evolution (LTE) standard and fulfill the requirements of the IoT use cases such as optimized through the network low data rate transfers, world-wide coverage, large number of devices supported by single-cell and extended battery lifetime [3].

To reduce the power consumption NB-IoT uses two new mechanisms – the Extended Discontinuous Reception (eDRX) and the Power Saving Mode (PSM) [4]. Using these techniques, the radio modem is effectively switched off during the idle periods and the link doesn't need to be reestablished for every data transfer. The traditional way for transferring data over LTE network is through the Internet Protocol (IP) over the network User Plane. The IP mechanism requires intensive signaling. Signaling messages need to activate the RF transmitter and use a consequent amount of energy. NB-IoT power consumption can be optimized by using non-IP transfer over the Control plane.

### IV. EXPERIMENTAL SET UP

To test the different ways of optimizing the energy consumption of an NB-IoT device, a specialized measuring system was developed. The system block diagram is presented in Fig. 3. The system measures the instantaneous power $p(t) = I(t)*V(t)$ consumed by the NB-IoT device. The energy is obtained by integrating $p(t)$ over time. $V_{RF}$ is a voltage proportional to the transmitted RF power.

<figure><img src="image_5.png" /><figcaption>Fig. 3. NB-IoT device power and energy recording system</figcaption></figure>
The log amplifier increases the dynamic range and allows the measurement of the standby current as well as the current during the RF transmission.

Fig. 4 shows the measurement set up. A spectrum analyzer is used to monitor the RF transmission of the device.

<figure><img src="image_6.png" /><figcaption>Fig. 4. Measurement set-up</figcaption></figure>

The NB-IoT device can be configured in different modes and transfer a data block to a standard server or an echo server. By using an echo server, it is possible to measure the round-trip delay time and the speed of the network. For each mode, the energy and power consumption are measured in real-time during the different stages of the transmission (connection establishment, data transfer, waiting for acknowledgment, connection release). Thus, it is possible to measure the energy efficiency of the new NB-IoT specific configuration (PSM, eDRX) and data transfer modes (IP over User plane and non-IP over the Control plane). For a more detailed analysis, it is possible to record a log stream file from the module and correlate the log data and the device status with the power record.

## V. MEASUREMENT RESULTS

Measurements were carried out on the 1NCE operator's network in Munich (Germany). Fig. 4 shows a real record of the power current ($I$) synchronously with the transmitted RF power ($V_{RF}$). The transmission power depends of the propagation conditions and the distance from the base station. To assess the worst case all measurements are made with the maximum RF power of 23 dBm. The distance to the base station is around 2 km. The device is powered with a voltage of 3.8 V.

Table 1 shows the current consumed by the module in different states.

<table><caption>TABLE 1</caption><thead><tr><td>Device mode</td><td>Current [mA]</td></tr></thead><tbody><tr><td>Standby</td><td>0.0025</td></tr><tr><td>Reset mode</td><td>2.1</td></tr><tr><td>Active mode (receiver OFF)</td><td>8.5</td></tr><tr><td>Active mode (receiver ON)</td><td>50</td></tr><tr><td>Transmitter ON (23 dBm RF power)</td><td>200</td></tr></tbody></table>

A typical record is shown in Fig. 4. A block of 128 bytes is sent to a server. Link establishment, data transfer and the acknowledgment take 2 s. The transfer time for the data packet

is 0.2s. After 15 s inactivity the link is released (Radio Resources Connection - RRC release). In the standard configuration, the energy used to transfer a 128-byte, to receive an acknowledgment and to release the link after the inactivity timer (IT) is 700 µWh (2.5 J).

<figure><img src="image_7.png" /><figcaption>Fig. 4. Current consumption of the NB-IoT module during the different phases of the data transmission</figcaption></figure>

During the inactivity period, the receiver of the NB-IoT device is switched on, and this creates an unnecessary consumption of energy. This problem can be solved by using the discontinuous reception mode (sDRX).

<figure><img src="image_8.png" /><figcaption>Fig 5. Discontinuous reception (eDRX mode)</figcaption></figure>

A very effective way to reduce energy consumption has proven to be the Release Assistance (RA) feature. When non-further uplink and downlink data transmission is expected the device can send a request to the network to quickly release the connection. In this way, the inactivity timer can be avoided thus saving energy. With RA a 128 bytes bloc can be sent and acknowledged with only 80 µWh (0.29 J). Compared to the standard transfer mode RA needs 90% less energy!

The round-trip delay of the tested network and echo-server is less than 0.3 s.

According to the measurements for SARA-N211 NB-IoT device, two AA battery with 2.5 Ah capacity can provide the energy necessary to transfer 1300 bytes per day for 10 years.

## VI. VIRTUAL PLC

The configuration in Fig. 2c suggests an interesting possibility to realize the PLC functions entirely by software inside the network. In fact, since the data of the I/O system pass through the network, it is quite possible that they are processed directly inside the network. This leads us to the notion of the 'virtual
PLC. This concept is illustrated in Fig. 6. Of course, the realization of this idea in practice raises the issue of the “real time” performance of a software PLC inside the network. The idea of "virtual PLC" requires further study.

<figure><img src="image_9.png" /><figcaption>Fig. 6. "Virtual" PLC</figcaption></figure>

In this use case the real hardware platforms can serve as a reference for the performance of the virtual PLC implementation.

The concept of virtual PLC is closely related to modern automation techniques of Hardware in the Loop (HITL) and Digital Twins (DT). Both HITL and DT are currently the object of intense scientific research.

## VII. CONCLUSION

In this paper we have suggested the use of the PLC hardware platforms developed in the framework of the Asean Factori 4.0 project for research and development purposes. Two examples of possible research areas were presented - the use of NB-IoT type cellular networks to link sensors and actuators (I/O system) to the PLC and the introduction of the notion of the “virtual PLC” or “hardware-less PLC”.

A large number of other research possibilities exist as well.

Asean Factori 4.0 is a project oriented towards university teaching of modern automation technologies. However, in the university context, teaching and research are inseparable. The extension of the project to research and development type applications can only be beneficial to all participants (students, teachers, trainers and companies specialized in automation).

From this point of view, Asean Factori 4.0, which provides a solid intellectual and material background, also represents an opportunity for academic and applied research.

## ACKNOWLEDGMENT

This paper is based on a project co-funded by the ERASMUS+ Program of the European Union: Asean Factori 4.0, Across South East Asian Nations: From Automation and Control Training to the Overall Roll-out of Industry 4.0, 609854-EPP-1-2019-1-FR-EPPKA2-CBHE-JP.

## REFERENCES

[1] Asean Factori 4.0 Project Website. [Online], Available at: https://aseanfactori-erasmus-project.com

[2] J. M. Thiriet, D. Genon-Catalot, S. Mocanu, and H. Yahoui, "Industry 4.0: educational platforms disseminations in South-East Asia in the field of automation", The 30th Annual Conference of the European Association for Education in Electrical and Information Engineering (EAEIE), 2021, Prague, Czechia, pp. 67–70.

[3] 3ETSI TS 103 357 Version 1.1.1, "Short Range Devices; Low Throughput Networks (LTN); Protocols for Radio Interface A", June 2018.

[4] GSM Association, "NB-IoT Deployment Guide to Basic Feature set Requirements", Version 1.002, 2 August 2017, Available at: www.gsma.com/newsroom/wp-content/uploads/CLP.28-v2.0.pdf.