A Comprehensive Review of IoT Networking Technologies for Smart Home Automation Applications

: The expediential increase in Internet communication technologies leads to its expansion to interests beyond computer networks. MEMS (Micro Electro Mechanical Systems) can now be smaller with higher performance, leading to tiny sensors and actuators with enhanced capabilities. WSN (Wireless Sensor Networks) and IoT (Internet of Things) have become a way for devices to communicate, share their data, and control them remotely. Machine-to-Machine (M2M) scenarios can be easily implemented as the cost of the components needed in that network is now affordable. Some of these solutions seem to be more affordable but lack important features, while other ones provide them but at a higher cost. Furthermore, there are ones that can cover great distances and surpass the limits of a Smart Home, while others are more specialized for operation in small areas. As there is a variety of choices available, a more consolidated view of their characteristics is needed to ﬁgure out the pros and cons of each of these technologies. As there are a great number of technologies examined in this paper, they are presented regarding their connectivity: Wired, Wireless, and Dual mode (Wired and Wireless). Their oddities are examined with metrics based on user interaction, technical characteristics, data integrity, and cost factor. In the last part of this article, a comparison of these technologies is presented as an effort to assist home automation users, administrators, or installers in making the right choice among them.


Introduction
The continuous advances performed regarding Integrated Circuits (ICs) technology enabled the introduction of Micro Electro Mechanical Systems (MEMS) [1]. MEMS include microsensors, microactuators, micro-electronics, and other microstructures within tiny dimensions ( Figure 1).

Introduction
The continuous advances performed regarding Integrated Circuits (ICs) technology enabled the introduction of Micro Electro Mechanical Systems (MEMS) [1]. MEMS include microsensors, microactuators, micro-electronics, and other microstructures within tiny dimensions ( Figure 1). The next goal was to wirelessly interconnect sensing MEMS. In this way, WSNs (Wireless Sensor Networks) were introduced [2]. WSNs consist of MEMS-based devices, called sensing nodes that, despite their small size, have enhanced capabilities. Specifically, sensing nodes cannot only monitor ambient conditions in wide areas of interest but also process and transmit sensed data [3]. This makes WSNs ideal for supporting a practically endless range of applications [4][5][6][7][8][9][10], although their operation is obstructed mainly due to their limited energy sustainability [11][12][13], but also because of other problems such as congestion, vulnerable security, connectivity loss, insufficient coverage, and deteriorated Quality of Service (QoS) [14][15][16][17][18][19][20].
The interconnection of the sensing nodes through Internet technologies led to the birth of IoT [21][22][23]. With IoT technology, all Things (devices) can be managed and configured remotely, such as Cyber-Physical Systems (CPS) that interconnect the physical and cyber worlds with telecommunications.
The application of IoT in Home Automation (H.A.) systems led to the development of the so-called Smart Home sector [24][25][26]. In Smart Homes, systems controlled manually, such as heating, cooling, lighting, and other appliances, can be monitored and controlled remotely. A cyber-physical system, as depicted in Figure 2, takes measurements concerning temperature, humidity, and energy consumption, which can be displayed to a remote user, giving them the capability to initiate actions through appropriate actuators and modify them to a desirable level in a closed-loop feedback control scheme where communications are vital [27]. The most common example, regarding home comfort, is for a user to control their HVAC (Heating, Ventilation, and Air Conditioning) through a smartphone, tablet, or PC. The home temperature can be adjusted from a remote location to the appropriate one for its residents. As the growth of IoT began, many companies developed sensors, actuators, and control systems that are IoT compatible [28]. The need for interconnecting them with sensors realized by other vendors has led to the development and growth of many standard communication technologies. BACnet [29], Dupline [30], Ethernet, and KNX [31] were the first to be used that focus on Home Automation and the establishment of the so-called Smart Home domain. Later on, new technologies, i.e., Bluetooth [32], Wi-Fi [33], Zigbee [34], and Z-Wave [35], were introduced. There are also ones used to offer more capabilities and innovative features, such as 6LowPAN [36], EnOcean [37], Insteon [38], mioty, and Thread [39]. Technologies such as LoRA, mioty, Sigfox, LTE (5G), and NB-IoT are also used but aim to cover larger distances. In the past years, an effort was made by large companies, e.g., Apple (HomeKit) [40], Google (Alexa), and Samsung (SmartThings) [41], with the introduction of consumer products targeting smart homes and unifying them with one application regardless of the short-range communication technology used (BLE, Wi-Fi, The message size is 228 Bytes, while the data rates provided can reach up to 1.25 Mbps. Regarding coverage, it can reach distances up to 2700 m in wired connections.
Devices or systems can be separated into smaller groups of intelligent elements, called nodes, creating a smart network [64][65][66].

X10
It is one of the oldest home automation systems, as it was introduced in 1975. This technology is open-sourced and used for remotely controlling X-10's compliance transmitters and receivers. It has two modes for connections: • Wired: powerlines already pre-installed in every home; • Wireless: RF.
Short messages (commands) are used and broadcasted by transmitters to the receiving unit and processed by a unique ID. Receivers read this information and compare it with the receiving ID to determine if it matches their own. If the condition is met, then the whole message is downloaded and processed.
Due to the nature of this technology, data rates of 60 bps are provided, covering distances up to 30 m. Therefore, it is mostly used in automation networks such as lightning, home appliance, and security sensors [43,67].

Insteon
This technology is X10's successor; it provides backward compatibility with all existing devices supporting the technology (operating in 132 KHz) despite the commands not being similar. Its network consists of both wired and wireless connections providing MESH connections between them and ensuring connection redundancy [38,43,44,64,66].

Wireless Communication Technologies
These technologies are introduced to solve the need for interfacing with the existing home infrastructure and to provide a low-cost, high-efficiency solution for device communication. They can be divided into two major categories, according to the distance they cover.

Short Range
Short-range technologies can be used primarily on small buildings and homes, providing high-speed and high-availability connections between devices. 6LowPAN IPv6 over low-power wireless personal area networks is used for home automation systems and is characterized by its simplicity and low cost. It provides wireless connectivity where serious power constraints are needed. It makes use of IEEE 802.15.4 standard in the lowest OSI-7 layers [53] and IPv6 (IP version six) protocol for communications.
This technology is characterized as WPAN (Wireless Personal Area Network), exchanging data packets of 100 bit, while achieving data rates up to 250 Kbps and covering distances up to 200 m. It also provides mesh capabilities, but with a device making multiple wireless concurrent connections with more than one neighboring device. If its primary connectivity is lost, communication can still be established through another connection in the same network.

EnOcean
This technology is a wide-spreading technology, as it provides energy harvesting capabilities in wireless IoT and in-home automation. Every device in this WPAN (Wireless Personal Area Network) does not require any external energy source or battery [45].

Thread
Thread is a technology that is also based on the 802.15.4 standard, originated by seven companies (ARM (Softbank), Big Ass Fans, Freescale (NXP), Nest Labs (Google), Samsung, Silicon Labs, Yale Locks), which formed the Thread Group Inc. in 2015 [45,90].

Wi-Fi
This network technology is very popular, as it is known for the interconnection of various everyday devices. The 802.11ac standard (released in 2013) operates at the frequency bands of 2.4 GHz and 5 GHz, achieving data rates from 600 Mbps to 6. As a well-known and used technology for end-user devices, connections with almost all known home automation technologies are provided by vendors.
In 2014, the standard 802.11af of Wi-Fi enhanced its capabilities by improving energy management and efficiency. With the use of the existing WLAN topology, TV White Space frequencies (54 MHz-97 MHz band), and four channels for communications, the area covered remains 100 m, while the data rates can reach or surpass 400 Mbps.
802.11ah (WiFi HaLow) standard, newly introduced by IEEE and released in 2017, is an evolution of the 203.11af and is aimed at IoT devices. It provides many power-constrained stations, up to 100 m of area coverage, using frequencies of 900 MHz and network speeds of 4 Mbps. This technology also supports channels of 1 MHz/2 MHz for use in IoT, which can be increased up to 16 MHz to achieve greater data rates [33,56,75,[98][99][100].

Z-Wave
Z-Wave is a proprietary technology used by many vendors for home automation and IoT. It is characterized as low-cost, providing low-power transmissions. As described in Paetz (2013) [101], this technology has static routing and is implemented with a centralized routing table. Routing calculations are embedded into the messages so their forwarding behavior can be indicated (Fuller) [102].

Long Range
Long-range connections are mostly used for connections in larger buildings or architecture, providing availability without the use of repeaters.

DASH7
Industry-standard DASH7 Alliance Protocol (D7AP) is a standard based on the ISO/IEC 18000-7 and applied in wireless sensors and actuators. As its primary function design, it is based on the BLAST (Bursty, Light Data, Asynchronous Transitive) concept [80]. It operates on unlicensed low wireless frequencies 433 MHz, 868 MHz (EU), and 916 MHz (US), making the technology capable of reaching distances of 10 Km. Its message length is 256 Byte and provides data rates up to 200 Kbps achieving low latency when connected with moving network-capable objects [80]. Communication is done instantly (bursty) without containing any heavy data, such as audio or video [112], making it capable of light data payloads used in conventional applications.

LoRa (Long Range)
LoRa (Long Range), as the acronym displays, was first introduced in 2015 by Cycleo [122] and promoted to consumers by Semtech [123], is an open standard, used mostly for wireless systems separated by great distances with the use of unlicensed RF bands.
It is described as LPWAN (Low Power Wide Area Network) or WWAN (Wireless Wide Area Network) and is used for long-range data transmissions, more than 10 km (up to 20 km), while consuming very low energy. This is achieved due to the low frequencies used, its' message protocol (LoRaWAN) of 255 Bytes, and the low data rates supported (0.3-50 Kbps). As can be seen, it is suitable for applications exchanging a low set of data for long ranges without having to replace batteries for many years (more than 10 years) [124]. Mainly, it is used in agriculture, but there are also applications developed for H.A.
LTE (5G/NB-IoT) LTE (Long Term Evolution) is a very popular networking technology, well known for mobile phone communications used worldwide. It was introduced by 3GPP in 2008 and is based on the already existing networks GSM/EDGE and UMTS/HSPA, having as its primary objective faster data rates for mobile networking devices. To achieve that, new techniques of digital signal processing were introduced.
First, 2G was provided to 90% of the world's population, but its' main aim and target was mostly for voice [136]. Therefore, 3G has been introduced, providing more services than voice for a great amount of data. Emerging new technologies such as smartphones and tablets increased the need for higher data rates and led to its evolution in 2012 (4G).
Further, 5G was built on the foundations of its successors, providing even higher data rates of 10 Gbps, reliability , and encryption (AES256). For IoT and smart home implementations, special modes of this technology are used, LTE CAT-0, LTE CAT-M, and NB-IoT. These are optimized for IoT and smart buildings, reducing the complexity while covering the same range of the same infrastructure.
With the introduction of 3GPP release 12, a new category for UE (User Equipment) is supported. This evolution in Cat 0 (Category 0) devices resulted in a significant increase in their battery life. The most notable changes are:

•
The throughput for Uplink and Downlink is reduced to 1 Mbps; • The number of antennas is now decreased from 2 to 1; • The UE receiver bandwidth is reduced to 1.4 MHz, which can allow the reduction of substantial complexity; • UE can still operate in existing LTE system bandwidths up to 20 MHz; • A UE with a lower power class allows the integration of a power amplifier in a system provided in a single chip. The 3GPP releases 13 and 14 are widely known as NB-IoT, and it is mostly used for IoT implementations [137]. Huawei Technologies Co. Ltd. was one of the major companies focusing on this technology, providing enhanced, long-range coverage with the support of a substantial number of low-throughput devices [138]. Devices in this network are characterized by enhanced network architecture, low response time, low delay sensitivity, very low cost, and low energy consumption. The main advantage of this technology is the ability, when deployed in authorized frequency bands, to make use again of its core network.
As IoT devices do not require high data rates, the size of the message varies according to the network deployment, and transmission speed can be up to 204.8 Kbps and 234.7 Kbps for upload and download, respectively. Messages are encrypted with the AES256 Standard (Advanced Encryption), providing extra security for the information exchanged. Furthermore, this technology provides great data integrity, as it implements SNOW 3G [139] or ATR-128 CMAC (Cipher-based Message Authentication Code) with 4 Byte MIC (Message Integrity Code) QoS mechanism. Due to its origin, LTE, is supported by many developers creating applications for remote management of systems such as traffic control and home automation [81,99,129,132,134,137,138,[140][141][142][143].

Mioty
This is a brand-new, open technology created and developed by Fraunhofer Institute in 2016 according to the ETSI telegram splitting ultra-narrow band (TS-UNB) technical specification for low-throughput networks (TS 103 357) and provided to the public through the Canadian company BehrTech. It is a long-range platform (WWAN) covering distances up to 15 km (without obstacles), with data rates of 512 bps. It provides low consumption and long battery life; therefore, it is characterized as LPWAN.The innovation in mioty is the way that messages are transmitted. They are formatted as short telegrams of packets sizing  Bytes, but they are not sent simultaneously. Using TSMA (Telegram Spread Multiple Access), a random MAC is used, dividing its' message transmission into several shorter packages (fragments). Then, these are distributed randomly on different channels and timeslots. This technique, according to its developers, can tolerate packet loss of up to 50%. In Figure 3, the mioty telegram splitting technique is depicted.
As Mioty is a new technology, there is not so much information available and opensource developments concerning the design of Gateways and wireless nodes, and therefore it is difficult to analyze in-depth the performance of the technology compared with other LPWAN technologies [113,128,134,144,145]. mioty is the way that messages are transmitted. They are formatted as short telegrams of packets sizing  Bytes, but they are not sent simultaneously. Using TSMA (Telegram Spread Multiple Access), a random MAC is used, dividing its' message transmission into several shorter packages (fragments). Then, these are distributed randomly on different channels and timeslots. This technique, according to its developers, can tolerate packet loss of up to 50%. In Figure 3, the mioty telegram splitting technique is depicted.

Sigfox
It is a long-range communications technology created and developed in 2010 in Toulouse, France [129]. It is defined by the ETSI ERM TG28 standard and characterized as LTN (Low-Throughput Network).
Sigfox uses the free, unlicensed bands of: The distances covered are greater than 10 km, achieving data rates up to 100 bps for uploading and 600 bps for downloading. Its' message length is 8-12 Bytes and provides heterogeneity as modules are developed, providing a connection of its gateway to BLE and Wi-Fi. Unfortunately, due to its' slow data rate, QoS is not provided but provides encryption to the packets exchanged.
One characteristic that can be pointed out is a feature called spatial diversity. As its terminal is not attached to a single base station, like most mobile cellular systems, when following the right deployment, a message sent by a terminal can be received by many base stations [70,81,99,129,133,134,146].

Technologies' Comparison and Discussion
In this section, a detailed comparison of the technologies studied in this review will be presented.
These will be presented in four separate groups to reduce information overloading. The key groups are wired, wireless (short range), wireless (medium-long range), and dual mode (using both wired and wireless communications). The separation of wireless protocols into short-range and medium-long range is done due to the multiple technologies available.
Wireless technologies can be classified according to the distance they cover ( Figure 4). These are:   Figure 4 illustrates all the technologies according to the distance they can cover. Another classification of these technologies' characteristics is:

User Interaction
According to the information provided in Tables 2-5, technologies, mostly wired, have been provided to consumers for over 20 years. These are BACnet, Bluetooth, Dupline, Ethernet, KNX, LonWorks, Wi-Fi, and X10. Three of them are known for computer and mobile device networking. These are the most popular ones in building automation. In Europe, the most known technologies in the market are Dupline and KNX, while in the US, they are BACnet, X10, and its successor, Insteon. Among the most recent technologies, are Zigbee and Z-Wave the most known ones.

User Interaction
According to the information provided in Tables 2-5, technologies, mostly wired, have been provided to consumers for over 20 years. These are BACnet, Bluetooth, Dupline, Ethernet, KNX, LonWorks, Wi-Fi, and X10. Three of them are known for computer and mobile device networking. These are the most popular ones in building automation. In Europe, the most known technologies in the market are Dupline and KNX, while in the US, they are BACnet, X10, and its successor, Insteon. Among the most recent technologies, are Zigbee and Z-Wave the most known ones.

Energy/Cost
Energy consumption constitutes one of IoT and home automation's major goals. Every improvement presented for this technology aims for this characteristic. This feature is most needed for wireless-based technologies, where a component can be in an area without a stable power supply; therefore, batteries must be used. Therefore, there is a need for them to consume a small amount of energy for their operation and to have better efficiency (power loss). All wireless technologies provide this feature except Wi-Fi (802.11 a/b/n/ac/ax) and LTE, as they are mainly used for high data rates (multimedia applications), and therefore more energy is needed. Transmission power is very low in technologies that use short-range (0-100 mW) features that vary according to the obstacles in between transceivers causing interference.
Wired medium technologies, as they are constantly connected to a power supply, are not so focused on low energy consumption. As in wireless, apart from the ones used for high data rates, energy consumption is small.
The best technology regarding power consumption and efficiency is EnOcean. As an energy harvesting technology, the power needed for its operation is produced by it; therefore, the overall number is zero. Its' transmission power (TX-power) is still the lowest at about 50 μW. Most of the short-range wireless technologies also have this factor in very low numbers from 0-100 according to the distance and the obstacles blocking their transmission. Two factors have an impact on the power transmitted and increase its value: the frequency used (the greater, the more power is needed) and the distance they cover. Therefore, long-range technologies such as DASH7, Sigfox, LTE, NB-IoT, LoRa, and mioty values greater than 10 mW boost the signal to cover the distance, with the first two being the most efficient while the following two (due to the high data transmission and their design) consume the most (200 mW). In contrast to the TX-power, NB-IoT, LoRa, and mioty provide very low consumption, while Sigfox has high energy consumption, and DASH7 is low. In Tables 14-17, energy and cost features are displayed.

Technical Characteristics
Technical characteristics are an important category to examine the technologies' capabilities in more detail. According to "Trends in Home Automation Systems and Protocols" [53], all of them follow the OSI-7 reference model. According to its specification, it has seven layers named from the bottom up: physical, data link, network, transport, session, presentation, and application. These technologies either have the same structure or many of them merge two or more layers into one, described then as OSI-5 of OSI-4. Tables 6-9 display these characteristics.

Technical Characteristics
Technical characteristics are an important category to examine the technologies' capabilities in more detail. According to "Trends in Home Automation Systems and Protocols" [53], all of them follow the OSI-7 reference model. According to its specification, it has seven layers named from the bottom up: physical, data link, network, transport, session, presentation, and application. These technologies either have the same structure or many of them merge two or more layers into one, described then as OSI-5 of OSI-4. Tables 6-9 display these characteristics.                       Table 5. Dual-mode home automation technology user interaction.

Home Automation Technologies
Actuator Netw. 2023, 12, x FOR PEER REVIEW 12 of 31  Table 3, a standard for low cost and energy with high efficiency. Other technologies use their proprietary solutions.
While there are many solutions regarding home automation in the market, many of them are extending their capabilities by providing support for security systems, remote metering, and medical appliances. Most of them offer an API (Application Programming Interface) to developers for them to include their technology in their products.    Table 3, a standard for low cost and energy with high efficiency. Other technologies use their proprietary solutions.
While there are many solutions regarding home automation in the market, many of them are extending their capabilities by providing support for security systems, remote metering, and medical appliances. Most of them offer an API (Application Programming Interface) to developers for them to include their technology in their products.    Table 3, a standard for low cost and energy with high efficiency. Other technologies use their proprietary solutions.
While there are many solutions regarding home automation in the market, many of them are extending their capabilities by providing support for security systems, remote metering, and medical appliances. Most of them offer an API (Application Programming Interface) to developers for them to include their technology in their products.    Table 3, a standard for low cost and energy with high efficiency. Other technologies use their proprietary solutions.
While there are many solutions regarding home automation in the market, many of them are extending their capabilities by providing support for security systems, remote metering, and medical appliances. Most of them offer an API (Application Programming Interface) to developers for them to include their technology in their products.   The demands for wireless communications with better energy efficiency have led to the old ones being improved, as well as the appearance of new ones. Many of them are based on IEEE 802.15.4, as can be seen in Table 3, a standard for low cost and energy with high efficiency. Other technologies use their proprietary solutions.
While there are many solutions regarding home automation in the market, many of them are extending their capabilities by providing support for security systems, remote metering, and medical appliances. Most of them offer an API (Application Programming Interface) to developers for them to include their technology in their products. Figure 5 is a schematic representation of the technologies' popularity according to the literature findings displayed in the aforementioned tables.   Table 3, a standard for low cost and energy with high efficiency. Other technologies use their proprietary solutions.
While there are many solutions regarding home automation in the market, many of them are extending their capabilities by providing support for security systems, remote metering, and medical appliances. Most of them offer an API (Application Programming Interface) to developers for them to include their technology in their products.

Technical Characteristics
Technical characteristics are an important category to examine the technologies' capabilities in more detail. According to "Trends in Home Automation Systems and Protocols" [53], all of them follow the OSI-7 reference model. According to its specification, it has seven layers named from the bottom up: physical, data link, network, transport, session, presentation, and application. These technologies either have the same structure or many of them merge two or more layers into one, described then as OSI-5 of OSI-4. Tables 6-9 display these characteristics.
An important technical characteristic has to do with data rates. While in building automation and IoT, high data rates are not required; since the required data to be exchanged are low, it is considered an advantage for handling future network speed demands. This feature can be seen in technologies where Ethernet or fiber optics media are used. Apart from the Ethernet, which natively uses these mediums, technologies that also use this kind of medium include BACnet (Ethernet medium), KNX (Ethernet medium), and LonWorks (fiber optics). For wireless communications, Wi-Fi, also used for computer networks and multimedia applications, is the fastest one. Other wired and many wireless technologies can provide low data rates, capable of managing the traffic issued by IoT devices. There are also wireless, long-range ones that offer even lower data rates due to the low frequency used for transmission. Figure 6 is a representation of the data rate used in each technology, while Figure 7 illustrates the data rates according to the packet size used in each one.

Technical Characteristics
Technical characteristics are an important category to examine the technologies' capabilities in more detail. According to "Trends in Home Automation Systems and Protocols" [53], all of them follow the OSI-7 reference model. According to its specification, it has seven layers named from the bottom up: physical, data link, network, transport, session, presentation, and application. These technologies either have the same structure or many of them merge two or more layers into one, described then as OSI-5 of OSI-4. Tables 6-9 display these characteristics.

Technical Characteristics
Technical characteristics are an important category to examine the technologies' capabilities in more detail. According to "Trends in Home Automation Systems and Protocols" [53], all of them follow the OSI-7 reference model. According to its specification, it has seven layers named from the bottom up: physical, data link, network, transport, session, presentation, and application. These technologies either have the same structure or many of them merge two or more layers into one, described then as OSI-5 of OSI-4. Tables 6-9 display these characteristics.   Figure 4 illustrates all the technologies according to the distance they can cover. Another classification of these technologies' characteristics is:

User Interaction
According to the information provided in Table 2, Table 3, Table 4 and Table 5 technologies, mostly wired, have been provided to consumers for over 20 years. These are BACnet, Bluetooth, Dupline, Ethernet, KNX, LonWorks, Wi-Fi, and X10. Three of them are known for computer and mobile device networking. These are the most popular ones in building automation. In Europe, the most known technologies in the market are Dupline and KNX, while in the US, they are BACnet, X10, and its successor, Insteon. Among the most recent technologies, are Zigbee and Z-Wave the most known ones.         AFH (Adaptive Frequencyhopping) [75] 315 MHz CSMA-CA CSMA-CA CSMA-CA CSMA-CA             technologies can provide low data rates, capable of managing the traffic issued by IoT devices. There are also wireless, long-range ones that offer even lower data rates due to the low frequency used for transmission. Figure 6 is a representation of the data rate used in each technology, while Figure 7 illustrates the data rates according to the packet size used in each one.  Of course, the most devices that can be supported by network technology, the more versatile this technology is. Technologies based on the 802.15.4 standard (apart from Thread) can have a significant number of devices in their network, 64,000. Some, such as Bluetooth, Dupline, Z-Wave, and X10, offer a small number of connected devices, while technologies can provide low data rates, capable of managing the traffic issued by IoT devices. There are also wireless, long-range ones that offer even lower data rates due to the low frequency used for transmission. Figure 6 is a representation of the data rate used in each technology, while Figure 7 illustrates the data rates according to the packet size used in each one.  Of course, the most devices that can be supported by network technology, the more versatile this technology is. Technologies based on the 802.15.4 standard (apart from Thread) can have a significant number of devices in their network, 64,000. Some, such as Bluetooth, Dupline, Z-Wave, and X10, offer a small number of connected devices, while Of course, the most devices that can be supported by network technology, the more versatile this technology is. Technologies based on the 802.15.4 standard (apart from Thread) can have a significant number of devices in their network, 64,000. Some, such as Bluetooth, Dupline, Z-Wave, and X10, offer a small number of connected devices, while others are capable of a very high number of devices, such as Ethernet, Insteon, Wi-Fi (v.6), LTE, NB-IoT, DASH7, mioty.
Mesh capability is offered by many networking technologies. It can be provided in two ways, in the first, a device has its data (routing) table with its neighborhood ones in the network it belongs to. If a connection is lost (dropped) to one element of the network, it can still be connected to the WPAN/WLAN using multi-hop mesh networking through their neighbor devices. All of the technologies (6LowPAN, Thread, Zigbee) based on the 802.15.4 standard for the PHY layer offer this feature, as well as BLE, DASH7, EnOcean, and Z-Wave. The second way is for each device to be connected to the same network, both wired and wirelessly. Insteon is the only technology supporting this feature. Mesh, though, can be achieved with the collaboration of wired and wireless technologies. Ethernet technology follows the same OSI model as Wi-Fi and also uses the TCP/IP protocol. Therefore, like a PC or a laptop, an IoT device can have both wired and wireless connections to the same network, and therefore mesh can be achieved. KNX can offer this feature by implementing its wired connection in collaboration with its wireless features or with the use of other technologies such as Zigbee or EnOcean. If one of these connections fails, connectivity to the network is provided by the other medium. A graphical representation of mesh technology in comparison with other known ones is shown in Figure 8 as indicated in [45]. two ways, in the first, a device has its data (routing) table with its neighborhood ones in the network it belongs to. If a connection is lost (dropped) to one element of the network, it can still be connected to the WPAN/WLAN using multi-hop mesh networking through their neighbor devices. All of the technologies (6LowPAN, Thread, Zigbee) based on the 802.15.4 standard for the PHY layer offer this feature, as well as BLE, DASH7, EnOcean, and Z-Wave. The second way is for each device to be connected to the same network, both wired and wirelessly. Insteon is the only technology supporting this feature. Mesh, though, can be achieved with the collaboration of wired and wireless technologies. Ethernet technology follows the same OSI model as Wi-Fi and also uses the TCP/IP protocol. Therefore, like a PC or a laptop, an IoT device can have both wired and wireless connections to the same network, and therefore mesh can be achieved. KNX can offer this feature by implementing its wired connection in collaboration with its wireless features or with the use of other technologies such as Zigbee or EnOcean. If one of these connections fails, connectivity to the network is provided by the other medium. A graphical representation of mesh technology in comparison with other known ones is shown in Figure 8 as indicated in [45]. Another important feature examined has to do with the communication protocols used for their communications. TCP/IP, also used in computer networks, is supported by most of the technologies presented. This is important for data exchanged from one technology to another. Other technologies exchange a very small amount of data; therefore, small frames or telegrams are used.
In each technology, variations can be seen regarding the distance covered and the data rates they achieve. Low-frequency wireless transmission data can be transmitted over large distances and consume a small amount of energy, but the network speeds are not so fast. These are 802.15.4-based technologies (6LowPAN, Thread, and Zigbee), Dash7, EnOcean, LoRa, NB-IoT, mioty, Sigfox, Wi-Fi (802.11ah), and Z-Wave. Technologies that use higher frequencies can only cover small distances, as the attenuation is significant while consuming significant energy, but in addition, they provide great data rates. In this category, LTE and Wi-Fi (802.11a/b/n/ac/ax) can cover large distances, and the energy used Another important feature examined has to do with the communication protocols used for their communications. TCP/IP, also used in computer networks, is supported by most of the technologies presented. This is important for data exchanged from one technology to another. Other technologies exchange a very small amount of data; therefore, small frames or telegrams are used.
In each technology, variations can be seen regarding the distance covered and the data rates they achieve. Low-frequency wireless transmission data can be transmitted over large distances and consume a small amount of energy, but the network speeds are not so fast. These are 802.15.4-based technologies (6LowPAN, Thread, and Zigbee), Dash7, EnOcean, LoRa, NB-IoT, mioty, Sigfox, Wi-Fi (802.11ah), and Z-Wave. Technologies that use higher frequencies can only cover small distances, as the attenuation is significant while consuming significant energy, but in addition, they provide great data rates. In this category, LTE and Wi-Fi (802.11a/b/n/ac/ax) can cover large distances, and the energy used is significant. Bluetooth operates at a high frequency and can cover small distances, but with the introduction of BLE, the amount of energy used is low.
In wired mediums, technologies based on Ethernet can be used in large areas, but they consume a significant amount of energy. Other technologies, such as Dupline, can cover great distances with small energy usage, but with the impact of low data rates.
Heterogeneity and the ability of each technology to co-exist and cooperate with other technologies is a future study in this paper. As can be seen in Figure 9, many technologies, such as Ethernet and Wi-Fi, are provided through the gateways of other technologies to be configured and controlled by a computer or smart device. they consume a significant amount of energy. Other technologies, such as Dupline, can cover great distances with small energy usage, but with the impact of low data rates.
Heterogeneity and the ability of each technology to co-exist and cooperate with other technologies is a future study in this paper. As can be seen in Figure 9, many technologies, such as Ethernet and Wi-Fi, are provided through the gateways of other technologies to be configured and controlled by a computer or smart device.

Security/Quality
Security is a significant factor for each technology, and the assurance of the information exchanged through these technologies is necessary. Either at a basic level or enhanced, a form of security is provided by almost all of the technologies examined. Old technologies, e.g., Dupline and X10, are the only ones in this review that do not provide this feature. For wired mediums, BACnet provides encryption to the transport layer with the use of TLS (Transport Layer Security), which is a 256-bit frame used with the rest of the data payload exchanged to provide encryption. Ethernet technology, according to its' 802.11AE definition, uses MACsec (Medium Access Control Security) and S-ARP (Secure Address Resolution Protocol) for data transfer security [148], applied in the Data link layer. In addition, in the network layer, with the use of TCP/IP protocol, IPSec encryption is provided, as well as TLS. In KNX, EIBsec is provided, making the technology's communications safe. In Tables 10-13, the main security and quality features are displayed.

Security/Quality
Security is a significant factor for each technology, and the assurance of the information exchanged through these technologies is necessary. Either at a basic level or enhanced, a form of security is provided by almost all of the technologies examined. Old technologies, e.g., Dupline and X10, are the only ones in this review that do not provide this feature. For wired mediums, BACnet provides encryption to the transport layer with the use of TLS (Transport Layer Security), which is a 256-bit frame used with the rest of the data payload exchanged to provide encryption. Ethernet technology, according to its' 802.11AE definition, uses MACsec (Medium Access Control Security) and S-ARP (Secure Address Resolution Protocol) for data transfer security [148], applied in the Data link layer. In addition, in the network layer, with the use of TCP/IP protocol, IPSec encryption is provided, as well as TLS. In KNX, EIBsec is provided, making the technology's communications safe. In Tables 10-13, the main security and quality features are displayed.   • Medium (1-10 km), also described as WNAN (Wireless Neighborhood Area Networks), covers areas from 1 km to 10 km. • Long-range (10-100 km), also known as WWAN (Wireless Wide Area Networks), is used for greater distances of coverage from 10 km to 100 km.

User Interaction
According to the information provided in Table 2, Table 3, Table 4 and Table 5 technologies, mostly wired, have been provided to consumers for over 20 years. These are BACnet, Bluetooth, Dupline, Ethernet, KNX, LonWorks, Wi-Fi, and X10. Three of them are known for computer and mobile device networking. These are the most popular ones in building automation. In Europe, the most known technologies in the market are Dupline and KNX, while in the US, they are BACnet, X10, and its successor, Insteon. Among the most recent technologies, are Zigbee and Z-Wave the most known ones.    [75] 315 MHz CSMA-CA CSMA-CA CSMA-CA CSMA-CA   [75] 315 MHz CSMA-CA CSMA-CA CSMA-CA CSMA-CA   [75] 315 MHz CSMA-CA CSMA-CA CSMA-CA CSMA-CA   [75] 315 MHz CSMA-CA CSMA-CA CSMA-CA CSMA-CA   [75] 315 MHz CSMA-CA CSMA-CA CSMA-CA CSMA-CA   [75] 315 MHz CSMA-CA CSMA-CA CSMA-CA CSMA-CA   [75] 315 MHz CSMA-CA CSMA-CA CSMA-CA CSMA-CA

Home Automation Technologies
Actuator Netw. 2023, 12, x FOR PEER REVIEW 20 of 31 Technologies using wireless transmission provide encryption to lower OSI layers and physical and data links. The most common method used is 128-bit size AES used by following the 802.15.4 standard. There are also long-range ones, such as Dash7, LoRa, and mioty, which use the same method. Bluetooth, Insteon, LTE, NB-IoT, and WiFi provide enhanced encryption with 256 bit. EnOcean provides a different method of encryption as it uses VAES (Variable AES) for providing extra security. Sigfox, as a low data rate technology, uses as a security mechanism for Key Generation and MAC verification sequence.
Apart from data security, integrity is an important feature of home automation technologies. Most of them use CRC (Cyclic Redundancy Check) to provide QoS (Quality of Service). This feature is provided by a set of bits, usually at the end of the message, as a ns. Actuator Netw. 2023, 12, x FOR PEER REVIEW 20 of 31 Technologies using wireless transmission provide encryption to lower OSI layers and physical and data links. The most common method used is 128-bit size AES used by following the 802.15.4 standard. There are also long-range ones, such as Dash7, LoRa, and mioty, which use the same method. Bluetooth, Insteon, LTE, NB-IoT, and WiFi provide enhanced encryption with 256 bit. EnOcean provides a different method of encryption as it uses VAES (Variable AES) for providing extra security. Sigfox, as a low data rate technology, uses as a security mechanism for Key Generation and MAC verification sequence.
Apart from data security, integrity is an important feature of home automation technologies. Most of them use CRC (Cyclic Redundancy Check) to provide QoS (Quality of Service). This feature is provided by a set of bits, usually at the end of the message, as a J. Sens. Actuator Netw. 2023, 12, x FOR PEER REVIEW 20 of 31 Technologies using wireless transmission provide encryption to lower OSI layers and physical and data links. The most common method used is 128-bit size AES used by following the 802.15.4 standard. There are also long-range ones, such as Dash7, LoRa, and mioty, which use the same method. Bluetooth, Insteon, LTE, NB-IoT, and WiFi provide enhanced encryption with 256 bit. EnOcean provides a different method of encryption as it uses VAES (Variable AES) for providing extra security. Sigfox, as a low data rate technology, uses as a security mechanism for Key Generation and MAC verification sequence.
Apart from data security, integrity is an important feature of home automation technologies. Most of them use CRC (Cyclic Redundancy Check) to provide QoS (Quality of Service). This feature is provided by a set of bits, usually at the end of the message, as a J. Sens. Actuator Netw. 2023, 12, x FOR PEER REVIEW 20 of 31 Technologies using wireless transmission provide encryption to lower OSI layers and physical and data links. The most common method used is 128-bit size AES used by following the 802.15.4 standard. There are also long-range ones, such as Dash7, LoRa, and mioty, which use the same method. Bluetooth, Insteon, LTE, NB-IoT, and WiFi provide enhanced encryption with 256 bit. EnOcean provides a different method of encryption as it uses VAES (Variable AES) for providing extra security. Sigfox, as a low data rate technology, uses as a security mechanism for Key Generation and MAC verification sequence.
Apart from data security, integrity is an important feature of home automation technologies. Most of them use CRC (Cyclic Redundancy Check) to provide QoS (Quality of Service). This feature is provided by a set of bits, usually at the end of the message, as a Technologies using wireless transmission provide encryption to lower OSI layers and physical and data links. The most common method used is 128-bit size AES used by following the 802.15.4 standard. There are also long-range ones, such as Dash7, LoRa, and mioty, which use the same method. Bluetooth, Insteon, LTE, NB-IoT, and WiFi provide enhanced encryption with 256 bit. EnOcean provides a different method of encryption as it uses VAES (Variable AES) for providing extra security. Sigfox, as a low data rate technology, uses as a security mechanism for Key Generation and MAC verification sequence.
Apart from data security, integrity is an important feature of home automation technologies. Most of them use CRC (Cyclic Redundancy Check) to provide QoS (Quality of Service). This feature is provided by a set of bits, usually at the end of the message, as a verification of the data being transmitted or received. If this information is confirmed by the counted data, then the information has been exchanged successfully. There are variations of the bits used for this feature, KNX (with the use of TCP/IP protocol), EnOcean, and Z-Wave provide 8. Technologies with more data exchanged, such as6LoWPAN, BACnet, Bluetooth, Insteon, Thread, and Zigbee, use 16 bit. There are also ones proving an even larger number of bits (32), e.g., BACnet, Ethernet, KNX, and WiFi. Low-data transmission technologies, e.g., Dupline, LoRa, Sigfox, and X10, do not provide integrity mechanisms.
NB-IoT varies in this category as it uses one of the algorithms (SNOW 3G or ATR-128 CMAC) with 4 Byte MIC. The first one is used by 3GPP to provide confidentiality of data based on UMTS (Universal Mobile Telecommunications Service) mobile networks [138]. It consists of two modules interacting with each other, using 32-bit registers [139]. ATR-128 is a proprietary algorithm performing 128-bit encryption, while CMAC is MAC (Media Access Control) scheme based on block-cipher providing data integrity and authenticity. MIC is a mechanism that ensures, through hash in the messages, that messages have not been altered.
Mioty, with its TSMA technique, provides a QoS mechanism, as it is designed for zero packet loss. If packets are lost, it can tolerate up to 50% of the packets to arrive to decode the information [134]. In Figure 10, the QoS and Encryption characteristics of each technology are presented. As depicted in Figure 11, wireless technologies use specific transmission bands. As a result, in a specific frequency, interference can occur, affecting the quality of data exchanged from one technology to a co-existing one. For this phenomenon to be avoided, each technology uses a specific mechanism to ensure data integrity. Most of them (6LoW-PAN, Dash7, Thread, WiFi, Z-Wave, Zigbee) use CSMA/CA (Carrier Sense Multiple Access-Collision Avoidance). It is applied in the Data Link OSI layer and performs a specific procedure to ensure the data is transmitted without collisions [97]. Another technique used for interference avoidance is frequency hopping. If the data exchanged use the same band, the transmitted channel (frequency) is changed to the next supported/available one [150]. As depicted in Figure 11, wireless technologies use specific transmission bands. As a result, in a specific frequency, interference can occur, affecting the quality of data exchanged from one technology to a co-existing one. For this phenomenon to be avoided, each technology uses a specific mechanism to ensure data integrity. Most of them (6LoWPAN, Dash7, Thread, WiFi, Z-Wave, Zigbee) use CSMA/CA (Carrier Sense Multiple Access-Collision Avoidance). It is applied in the Data Link OSI layer and performs a specific procedure to ensure the data is transmitted without collisions [97]. Another technique used for interference avoidance is frequency hopping. If the data exchanged use the same band, the transmitted channel (frequency) is changed to the next supported/available one [150].
result, in a specific frequency, interference can occur, affecting the quality of data exchanged from one technology to a co-existing one. For this phenomenon to be avoided, each technology uses a specific mechanism to ensure data integrity. Most of them (6LoW-PAN, Dash7, Thread, WiFi, Z-Wave, Zigbee) use CSMA/CA (Carrier Sense Multiple Access-Collision Avoidance). It is applied in the Data Link OSI layer and performs a specific procedure to ensure the data is transmitted without collisions [97]. Another technique used for interference avoidance is frequency hopping. If the data exchanged use the same band, the transmitted channel (frequency) is changed to the next supported/available one [150].

Energy/Cost
Energy consumption constitutes one of IoT and home automation's major goals. Every improvement presented for this technology aims for this characteristic. This feature is most needed for wireless-based technologies, where a component can be in an area without a stable power supply; therefore, batteries must be used. Therefore, there is a need for them to consume a small amount of energy for their operation and to have better efficiency (power loss). All wireless technologies provide this feature except Wi-Fi (802.11 a/b/n/ac/ax) and LTE, as they are mainly used for high data rates (multimedia applications), and therefore more energy is needed. Transmission power is very low in technologies that use shortrange (0-100 mW) features that vary according to the obstacles in between transceivers causing interference.
Wired medium technologies, as they are constantly connected to a power supply, are not so focused on low energy consumption. As in wireless, apart from the ones used for high data rates, energy consumption is small.
The best technology regarding power consumption and efficiency is EnOcean. As an energy harvesting technology, the power needed for its operation is produced by it; therefore, the overall number is zero. Its' transmission power (TX-power) is still the lowest at about 50 µW. Most of the short-range wireless technologies also have this factor in very low numbers from 0-100 according to the distance and the obstacles blocking their transmission. Two factors have an impact on the power transmitted and increase its value: the frequency used (the greater, the more power is needed) and the distance they cover. Therefore, long-range technologies such as DASH7, Sigfox, LTE, NB-IoT, LoRa, and mioty values greater than 10 mW boost the signal to cover the distance, with the first two being the most efficient while the following two (due to the high data transmission and their design) consume the most (200 mW). In contrast to the TX-power, NB-IoT, LoRa, and mioty provide very low consumption, while Sigfox has high energy consumption, and DASH7 is low. In Tables 14-17, energy and cost features are displayed.

Home Automation Technologies
frequency used (the greater, the more power is needed) and the distance they cover. Therefore, long-range technologies such as DASH7, Sigfox, LTE, NB-IoT, LoRa, and mioty values greater than 10 mW boost the signal to cover the distance, with the first two being the most efficient while the following two (due to the high data transmission and their design) consume the most (200 mW). In contrast to the TX-power, NB-IoT, LoRa, and mioty provide very low consumption, while Sigfox has high energy consumption, and DASH7 is low. In Tables 14-17, energy and cost features are displayed. frequency used (the greater, the more power is needed) and the distance they cover. Therefore, long-range technologies such as DASH7, Sigfox, LTE, NB-IoT, LoRa, and mioty values greater than 10 mW boost the signal to cover the distance, with the first two being the most efficient while the following two (due to the high data transmission and their design) consume the most (200 mW). In contrast to the TX-power, NB-IoT, LoRa, and mioty provide very low consumption, while Sigfox has high energy consumption, and DASH7 is low. In Tables 14-17, energy and cost features are displayed. According to the information provided in Table 2, Table 3, Table 4 and Table 5 technologies, mostly wired, have been provided to consumers for over 20 years. These are BACnet, Bluetooth, Dupline, Ethernet, KNX, LonWorks, Wi-Fi, and X10. Three of them are known for computer and mobile device networking. These are the most popular ones in building automation. In Europe, the most known technologies in the market are Dupline and KNX, while in the US, they are BACnet, X10, and its successor, Insteon. Among the most recent technologies, are Zigbee and Z-Wave the most known ones.

Home Automation Technologies
low numbers from 0-100 according to the distance and the obstacles blocking their transmission. Two factors have an impact on the power transmitted and increase its value: the frequency used (the greater, the more power is needed) and the distance they cover. Therefore, long-range technologies such as DASH7, Sigfox, LTE, NB-IoT, LoRa, and mioty values greater than 10 mW boost the signal to cover the distance, with the first two being the most efficient while the following two (due to the high data transmission and their design) consume the most (200 mW). In contrast to the TX-power, NB-IoT, LoRa, and mioty provide very low consumption, while Sigfox has high energy consumption, and DASH7 is low. In Tables 14-17, energy and cost features are displayed. mission. Two factors have an impact on the power transmitted and increase its value: the frequency used (the greater, the more power is needed) and the distance they cover. Therefore, long-range technologies such as DASH7, Sigfox, LTE, NB-IoT, LoRa, and mioty values greater than 10 mW boost the signal to cover the distance, with the first two being the most efficient while the following two (due to the high data transmission and their design) consume the most (200 mW). In contrast to the TX-power, NB-IoT, LoRa, and mioty provide very low consumption, while Sigfox has high energy consumption, and DASH7 is low. In Tables 14-17, energy and cost features are displayed. low numbers from 0-100 according to the distance and the obstacles blocking their transmission. Two factors have an impact on the power transmitted and increase its value: the frequency used (the greater, the more power is needed) and the distance they cover. Therefore, long-range technologies such as DASH7, Sigfox, LTE, NB-IoT, LoRa, and mioty values greater than 10 mW boost the signal to cover the distance, with the first two being the most efficient while the following two (due to the high data transmission and their design) consume the most (200 mW). In contrast to the TX-power, NB-IoT, LoRa, and mioty provide very low consumption, while Sigfox has high energy consumption, and DASH7 is low. In Tables 14-17, energy and cost features are displayed. low numbers from 0-100 according to the distance and the obstacles blocking their trans-mission. Two factors have an impact on the power transmitted and increase its value: the frequency used (the greater, the more power is needed) and the distance they cover. Therefore, long-range technologies such as DASH7, Sigfox, LTE, NB-IoT, LoRa, and mioty values greater than 10 mW boost the signal to cover the distance, with the first two being the most efficient while the following two (due to the high data transmission and their design) consume the most (200 mW). In contrast to the TX-power, NB-IoT, LoRa, and mioty provide very low consumption, while Sigfox has high energy consumption, and DASH7 is low. In Tables 14-17, energy and cost features are displayed. low numbers from 0-100 according to the distance and the obstacles blocking their trans-mission. Two factors have an impact on the power transmitted and increase its value: the frequency used (the greater, the more power is needed) and the distance they cover. Therefore, long-range technologies such as DASH7, Sigfox, LTE, NB-IoT, LoRa, and mioty values greater than 10 mW boost the signal to cover the distance, with the first two being the most efficient while the following two (due to the high data transmission and their design) consume the most (200 mW). In contrast to the TX-power, NB-IoT, LoRa, and mioty provide very low consumption, while Sigfox has high energy consumption, and DASH7 is low. In Tables 14-17, energy and cost features are displayed. low numbers from 0-100 according to the distance and the obstacles blocking their transmission. Two factors have an impact on the power transmitted and increase its value: the frequency used (the greater, the more power is needed) and the distance they cover. Therefore, long-range technologies such as DASH7, Sigfox, LTE, NB-IoT, LoRa, and mioty values greater than 10 mW boost the signal to cover the distance, with the first two being the most efficient while the following two (due to the high data transmission and their design) consume the most (200 mW). In contrast to the TX-power, NB-IoT, LoRa, and mioty provide very low consumption, while Sigfox has high energy consumption, and DASH7 is low. In Tables 14-17, energy and cost features are displayed. low numbers from 0-100 according to the distance and the obstacles blocking their trans-mission. Two factors have an impact on the power transmitted and increase its value: the frequency used (the greater, the more power is needed) and the distance they cover. Therefore, long-range technologies such as DASH7, Sigfox, LTE, NB-IoT, LoRa, and mioty values greater than 10 mW boost the signal to cover the distance, with the first two being the most efficient while the following two (due to the high data transmission and their design) consume the most (200 mW). In contrast to the TX-power, NB-IoT, LoRa, and mioty provide very low consumption, while Sigfox has high energy consumption, and DASH7 is low. In Tables 14-17, energy and cost features are displayed.   to buy licenses or extra fees in developing/operating them, so they can be available to everyone. Z-Wave is a proprietary technology, requiring device certification, which adds extra cost to the total value of a product. EnOcean devices are manufactured by a limited number of contractors, as it is not very popular yet. As a result, their value is a little higher than their competition. Wi-Fi and Bluetooth (in many cases) technologies are available in almost every end-user device in the market and can be used without the extra cost of acquiring an extra device or gateway. As a result, there are many solutions available at very low prices. Technologies using BLE standard to better manage their connected devices, require a gateway, adding a small additional cost. Wired technologies, which need a legitimate medium (hardware), are more expensive than wireless ones, which can be further increased with better quality cabling. As technologies become more popular, there are new solutions of devices introduced that can serve as a gateway (multi-mode gateway) in more than one smart home           to buy licenses or extra fees in developing/operating them, so they can be available to everyone. Z-Wave is a proprietary technology, requiring device certification, which adds extra cost to the total value of a product. EnOcean devices are manufactured by a limited number of contractors, as it is not very popular yet. As a result, their value is a little higher than their competition. Wi-Fi and Bluetooth (in many cases) technologies are available in almost every end-user device in the market and can be used without the extra cost of acquiring an extra device or gateway. As a result, there are many solutions available at very low prices. Technologies using BLE standard to better manage their connected devices, require a gateway, adding a small additional cost. Wired technologies, which need a legitimate medium (hardware), are more expensive than wireless ones, which can be further increased with better quality cabling. As technologies become more popular, there are new solutions of devices introduced that can serve as a gateway (multi-mode gateway) in more than one smart home   to buy licenses or extra fees in developing/operating them, so they can be available to everyone. Z-Wave is a proprietary technology, requiring device certification, which adds extra cost to the total value of a product. EnOcean devices are manufactured by a limited number of contractors, as it is not very popular yet. As a result, their value is a little higher than their competition. Wi-Fi and Bluetooth (in many cases) technologies are available in almost every end-user device in the market and can be used without the extra cost of acquiring an extra device or gateway. As a result, there are many solutions available at very low prices. Technologies using BLE standard to better manage their connected devices, require a gateway, adding a small additional cost. Wired technologies, which need a legitimate medium (hardware), are more expensive than wireless ones, which can be further increased with better quality cabling. As technologies become more popular, there are new solutions of devices intro-   are open-sourced; therefore, there is no need to buy licenses or extra fees in developing/operating them, so they can be available to everyone. Z-Wave is a proprietary technology, requiring device certification, which adds extra cost to the total value of a product. EnOcean devices are manufactured by a limited number of contractors, as it is not very popular yet. As a result, their value is a little higher than their competition. Wi-Fi and Bluetooth (in many cases) technologies are available in almost every end-user device in the market and can be used without the extra cost of acquiring an extra device or gateway. As a result, there are many solutions available at very low prices. Technologies using BLE standard to better manage their connected devices, require a gateway, adding a small additional cost. Wired technologies, which need a legitimate medium (hardware), are more expensive than wireless ones, which can be further increased with better quality cabling. As technologies become more popular, there are new solutions of devices intro-   are open-sourced; therefore, there is no need to buy licenses or extra fees in developing/operating them, so they can be available to everyone. Z-Wave is a proprietary technology, requiring device certification, which adds extra cost to the total value of a product. EnOcean devices are manufactured by a limited number of contractors, as it is not very popular yet. As a result, their value is a little higher than their competition. Wi-Fi and Bluetooth (in many cases) technologies are available in almost every end-user device in the market and can be used without the extra cost of acquiring an extra device or gateway. As a result, there are many solutions available at very low prices. Technologies using BLE standard to better manage their connected devices, require a gateway, adding a small additional cost. Wired technologies, which need a legitimate medium (hardware), are more expensive than wireless ones, which can be further increased with better quality cabling. As technologies become more popular, there are new solutions of devices intro-   are open-sourced; therefore, there is no need to buy licenses or extra fees in developing/operating them, so they can be available to everyone. Z-Wave is a proprietary technology, requiring device certification, which adds extra cost to the total value of a product. EnOcean devices are manufactured by a limited number of contractors, as it is not very popular yet. As a result, their value is a little higher than their competition. Wi-Fi and Bluetooth (in many cases) technologies are available in almost every end-user device in the market and can be used without the extra cost of acquiring an extra device or gateway. As a result, there are many solutions available at very low prices. Technologies using BLE standard to better manage their connected devices, require a gateway, adding a small additional cost. Wired technologies, which need a legitimate medium (hardware), are more expensive than wireless ones, which can be further increased with better quality cabling. As technologies become more popular, there are new solutions of devices intro- are open-sourced; therefore, there is no need to buy licenses or extra fees in developing/operating them, so they can be available to everyone. Z-Wave is a proprietary technology, requiring device certification, which adds extra cost to the total value of a product. EnOcean devices are manufactured by a limited number of contractors, as it is not very popular yet. As a result, their value is a little higher than their competition. Wi-Fi and Bluetooth (in many cases) technologies are available in almost every end-user device in the market and can be used without the extra cost of acquiring an extra device or gateway. As a result, there are many solutions available at very low prices. Technologies using BLE standard to better manage their connected devices, require a gateway, adding a small additional cost. Wired technologies, which need a legitimate medium (hardware), are more expensive than wireless ones, which can be further increased with better quality cabling. As technologies become more popular, there are new solutions of devices introduced that can serve as a gateway (multi-mode gateway) in more than one smart home technology, decreasing the cost of acquiring one for each of them. In Figure 12, a schematic representation of the technology behavior regarding energy and cost is given.

Discussion
There are many technologies offering a variety of capabilities in various applications. This review is focused on covering a more detailed and extensive coverage of the most known and used technologies available in WSN and home automation. This article is based on reviews focusing on statistical usage of home automation or IoT, on a number of technologies, or even some technical characteristics. This article is an attempt to gather most of the information available regarding popularity, technical characteristics, QoS, and even a small approach regarding energy/cost. It is an effort to compare many technologies at once.
The advantages of each technology vary. There are ones that focus on energy consumption, aimed at Green Energy, a term very popular nowadays. Some technologies combine this characteristic and also provide greater coverage. There are others providing higher data rates but with greater energy costs. Mesh propagation is another useful feature provided by technologies, ensuring connectivity, even if one network link is not working.
Security and quality are important factors for intercommunication between devices and ever for the end user. Proper data exchange is provided by most of the technologies covered in this review. There are also very important issues that need to be examined, such as security and more cyber-attacks. There is a lot of research available in this area, but this article does not provide much information as it would be expanding exponentially.

Conclusions
This review provides a detailed comparison of all technologies used in IoT-based networking for home automation. It is an effort to support end-users as well as installers and administrators to determine which one of these technologies is the most suitable, according to specific metrics. This survey, according to the knowledge of its authors, is the most complete when compared to other similar reviews. Specifically, various criteria have

Discussion
There are many technologies offering a variety of capabilities in various applications. This review is focused on covering a more detailed and extensive coverage of the most known and used technologies available in WSN and home automation. This article is based on reviews focusing on statistical usage of home automation or IoT, on a number of technologies, or even some technical characteristics. This article is an attempt to gather most of the information available regarding popularity, technical characteristics, QoS, and even a small approach regarding energy/cost. It is an effort to compare many technologies at once.
The advantages of each technology vary. There are ones that focus on energy consumption, aimed at Green Energy, a term very popular nowadays. Some technologies combine this characteristic and also provide greater coverage. There are others providing higher data rates but with greater energy costs. Mesh propagation is another useful feature provided by technologies, ensuring connectivity, even if one network link is not working.
Security and quality are important factors for intercommunication between devices and ever for the end user. Proper data exchange is provided by most of the technologies covered in this review. There are also very important issues that need to be examined, such as security and more cyber-attacks. There is a lot of research available in this area, but this article does not provide much information as it would be expanding exponentially.

Conclusions
This review provides a detailed comparison of all technologies used in IoT-based networking for home automation. It is an effort to support end-users as well as installers and administrators to determine which one of these technologies is the most suitable, according to specific metrics. This survey, according to the knowledge of its authors, is the most complete when compared to other similar reviews. Specifically, various criteria have been taken into consideration, such as popularity (adoption) and technical characteristics such as network size and network speed, quality, and cost. Another factor examined is heterogeneity and the ability of wireless technologies to avoid collisions when using the same frequency as other ones.
The most known technologies in IoT-based networking for home automation were examined from the older ones to the newly introduced ones. Some of them are opensourced, while others require a license to be purchased. Technologies such as KNX, Ethernet, WiFi, BLE, and Zigbee are quite popular with consumers, while LoRa, EnOcean, and mioty are rapidly increasing their popularity. Most focus on providing low-cost solutions and cover wide ranges providing low data rates. In addition, almost all of them provide a quality mechanism to ensure proper data exchange and security features for end-to-end information transmission. Regarding energy efficiency, technologies such as EnOcean and mioty provide high availability, but if cost is taken into account, LoRa is a more affordable choice. It can provide high efficiency, low budget, and satisfactory data rates.
Whilst there is a variety of solutions provided, and new ones are introduced every year, there is a need for these technologies to have a common interface for ensuring communication among them. This can be achieved with a method or a universal interface for managing each of them. This task is not simple, and an approach needs to be made focusing on the common characteristics these technologies have, such as the medium used (power line, Ethernet, frequency), the OSI layers [53] approach they use, and the protocol for exchanging their data. An approach using the TCP/IP v.6 protocol is a solution to be examined with the use of simulation tools and lab tests.

Conflicts of Interest:
The authors declare no conflict of interest.