Comparison of communication protocols for smart devices

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COMPARISON OF COMMUNICATION PROTOCOLS FOR SMART DEVICES

Robert Rakay, Alena Galajdova

Annotation

The urgency of the research. Modern trends in the automation focus on the implementation of new communication protocols, wireless data transfer and reduced costs. The communication part of every automation system is crucial, whether it is in the home or industry.

Target setting. During the design of the automated systems and the connection of different devices solution, developers have to address different requirements as addressing, data rates, data security, etc. The newest communication protocols and data transfer technologies provide significant data rate andMCU load reduction.

Actual scientific researches and issues analysis. To prepare this paper, different free available datasheets and experimental solutions were analyzed as well as conclusions of our previous and other ongoing experiments were used to create the knowledge base about this research topic.

Uninvestigated parts of general matters defining. There are many different communication solutions and every manufacturer of communication device provides its best solution. Not all of them can be described in this article.

The research objective. The different communication technologies were analyzed for future implementation to a smart devices for home automation, in this article.

The statement of basic materials. To propose a future model of home automation system, it is necessary to implement the newest communication technologies. Using the latest communication protocols, such as MQTT, CoAP or Websocket provides a good basis to solve this issue.

Conclusions. The proposed paper provides possibilities of the communication for a smart devices of the home automation system. Compared communication protocols have different advantages and disadvantages. The tested protocols meet the communication requirements for home automation devices.

Keywords: communication protocols; smart devices; home automation.

Анотація

Роберт Ракай, Алена Галайдова

ПОРІВНЯННЯ ПРОТОКОЛІВ ЗВ'ЯЗКУ ДЛЯ SMART ПРИСТРОЇВ

Актуальність теми дослідження. Сучасні тенденції автоматизації зосереджені на впровадженні нових протоколів зв 'язку, бездротовій передачі даних та зменшенні витрат. Комунікаційна частина кожної системи автоматизації є вирішальною, будь то в домашніх умовах чи в промисловості.

Постановка проблеми. Під час проектування автоматизованих систем та під 'єднання різних пристроїв розробникам доводиться задовольняти різні вимоги, такі, як адресація, швидкість передачі даних, безпека даних тощо. Найновіші протоколи зв 'язку та технології передачі даних забезпечують значне скорочення як швидкості передачі даних, так і завантаження мікроконтролера (MCU).

Аналіз останніх досліджень і публікацій. Під час підготовки даної роботи була проаналізована різноманітна документація у вільному доступі та експериментальні рішення, а також зроблені висновки з наших попередніх та інших проведених експериментів для створення бази знань за темою дослідження.

Виділення недосліджених частин загальної проблеми. Існує багато різних комунікаційних рішень, і кожен виробник пристрою зв'язку пропонує найкраще рішення. Не всі вони можуть бути описані в цій статті.

Постановка завдання. У даній статті проаналізовані різні комунікаційні технології для подальшої реалізації у смарт-пристроях для домашньої автоматизації.

Виклад основного матеріалу. Щоб запропонувати майбутню модель системи домашньої автоматизації, необхідно впровадити новітні комунікаційні технології. Використання останніх протоколів зв 'язку, таких як MQTT, CoAP або Websocket, дає хорошу основу для вирішення цієї проблеми.

Висновки відповідно до статті. Ця стаття пропонує можливості комунікації для розумних пристроїв системи домашньої автоматизації. Порівняні протоколи зв'язку мають різні переваги та недоліки. Перевірені протоколи відповідають вимогам зв'язку для пристроїв домашньої автоматизації.

Ключові слова: протоколи зв'язку; старт-пристрої; домашня автоматизація.

Introduction

Internet of Things is the term which is used to describe any form of applications that connect and make things - devices to interact through the internet. These devices and “their” network can be divided into Consumer Internet of Things (CIoT) and Industrial Internet of Things (IIoT). These classes of IoT share the same architecture composed of:

• Data collection

• Data storing

• Analysis of data

• Share of information

The IoT for customers or simply IoT represents the consumer oriented applications where all the devices are working to fulfil the needs of the consumer. Typical representatives of this class are smart devices of home automation systems, for example: refrigerator, washer, dryer, personal gadgets such as fitness sensors, smartwatches, etc.

The typical data volumes and rates are relatively low for these systems. The gathered data represent temperature, air pressure, number of steps and other information. The majority of applications are not mission or safety critical and the failure of the devices won't cause any harm, maximally financial or comfort [1].

The Industrial Internet of Things IIoT (Fig. 1) represents the industrial applications of interconnected devices which work together [2].

Typically devices operate in industrial grade transport systems, energy production or distribution and also medical environment, etc. The data volumes and transmission rates are relatively higher than in standard IoT. The majority of applications are critical in meanings of goals, aims and safety. Failure or bigger delay can cause great damage, both financial and environmental, e.g. failure of smart grid has a severe impact on the life of people and economy, the errors of intelligent traffic system can threaten drivers and walkers too. The majority of IIoT applications are system centric [3].

Fig. 1 Typical IIoT system

INDUSTRY 4.0 is the term describing the increased integration of information and communication technologies into production systems. According to the three leading German associations of mechanical engineering, information, communication and electrical industry, Industry 4.0 aims for optimization of value chains by implementing an autonomously controlled and dynamic production. With this integration better customization and individualization is carried out [4, 5].

The minimal requirements to determine the suitability of protocols are based on the shown automated monitoring system. (Fig. 2) The main goal of the system is to collect the temperature and humidity in three different room, and in case of emergency alarm the people are warned in the room through a signaling device, smartphone, tablet or notebook.

Fig. 2 Automated monitoring system

SENSORS MCU DEVICES

The collected data is processed from digital values to temperature and humidity in the microcontrollers and after that is sent to the cloud platform. The message body will consist of address and measured value. The values should be collected every 1 hour. The data is represented as numbers with two decimal places. Because of the experimental nature of the monitoring system the data collection is not time critical and the data rates are based on the available wireless connection to a local Wi-Fi router. For this system the measured values are not sensitive or private data therefore the security is not a critical aspect. The data collection will be carried out on one floor of an administrative building where all three rooms are adjacent. The aim of the experiments is not to test the technical characteristics of the standardized communication protocols but to find a suitable, easily applicable protocol for the proposed automation system.

Data processing

The data is collected from the cyber-physical world (CPS). CPS is the instrument to reach the increased automation. The main parts of CPS are microcontroller (MCU), actuators, sensor and communication interface. CPS can work autonomously and cooperate with the production environment.

By integrating CPS to the industrial system a “smart factory” is created. Depending on the type of applications data is being created from sensors or sensor networks for market analysis, web pages statistics, etc. The collected data is stored for on-line and off-line processing.

The stored data is analyzed, statistics are created and short/long term trends are updated. The processed data is shared to the relevant services or applications and subscribers. These systems are supposed to react, display, publish, and store the data. The key requirement in IoT is the efficient and scalable data sharing. The degree of performance depends on the application and sharing platform. Several standards to fulfil the requirements have been proposed to address this key need of the IoT [6].

There are two key aspects in the IoT: the devices and the server side that supports them. In some applications there is a third category, the gateway that supports data aggregation, event processing, bridging. The gateway connects the device to the wider Internet. The connections are based on GPRS connectivity, battery discharging, radio interference, etc, for both types of connections. Typical representatives of devices are embedded controllers of lower and higher classes, such as Arduino, Arduino Yun, and Raspberry Pi.

Some of these devices integrate sensor, some include communication interfaces. The communication between devices, Internet or the gateway is usually carried out by different models (Fig. 2):

• Direct Ethernet or Wi-Fi connectivity, TCP or UDP

• Bluetooth

• Bluetooth Low Energy (BLE)

• Near Field Communication (NFC)

• Zigbee

• SRF and point-to-point radio links

• UART or serial lines

• SPI or I2C wired buses

• ESPNow etc. [7]

There are many protocols to regulate the communication. For example HTTP protocol is very important for many devices, and a simple controller can create request such as GET and POST to read or write data to other device.

Although the HTTP is supported by many devices and is well known protocol, it has some disadvantages such as the size of the overhead, big requirement on memory size and power requirements. In order to fulfil needs of IoT we need simpler, smaller communication protocols.

Other requirements for IoT devices are:

• The ability to disconnect a rogue or stolen device.

• The ability to update the software on a device.

• Updating security credentials.

• Remotely enabling or disabling certain hardware capabilities.

• Locating a lost device.

• Wiping secure data from a stolen device.

• Remotely configuring Wi-Fi, GPRS or network parameters [8].

Testing of communication protocols. For the testing of basic communication properties we used the MCU ESP 32 and ESP 8266 connected to sensors and LEDs.

The main goal was to find the most suitable easily configurable communication protocol for embedded devices of smart homes and consumer IoT applications. The detailed parameters of MCU are described in the next section.

The ESP32 microcontroller. It supports different applications of different complexity, from simple sensing with one MCU to sensor networks. The MCU integrates two microchips with different operation cycles from 80-240 MHz. The main board includes various peripheries such as: capacitive sensors, hall sensor, communication interfaces SDIO, SPI, UART, I2S, and I2C. Bluetooth, Bluetooth Low Energy and Wi-Fi are available to support wireless communication. Technical details of MCU are described in the Table 1 [9, 10].

Table 1

Technical details of ESP8266 and ESP32