# Home Automation System Based on Intelligent Transducer Enablers
## 2 Related Work
### Smart Home Communication Technologies  
X10 [8] was the first general purpose wired home automation network technology and remains the most widely available protocol for communicating among electronic home devices. X10 was developed in 1975 in order to provide remote control to home devices and appliances. Technologies like the Universal Powerline Bus (UPB) [9] continue the legacy of X10 to implement powerline networking, while alternatives, like EnOcean [10], nanoNET [11], EIB/KNXRF [12], Z-Wave [13], 6 LoWPAN [14] and ZigBee [15], avoid using powerline in favor of wireless systems. Nowadays, the two wireless technologies that are probably most widely known are wireless LAN (IEEE 802.11) and Bluetooth (IEEE 802.15.1). Initially, it might seem that none of them is suitable for communicating in smart transducers: they are designed for transferring data at high speeds, it being difficult to fit into the power constraints and cost required by sensor networks. BLE emerged to solve the problems of consumption and cost while maintaining Bluetooth range. It aims to extend the use of Bluetooth to healthcare applications, fitness or safety. One interesting feature of BLE for IoT is Internet Protocol Support Profile (IPSP), which uses IPv6 packets to discover and communicate with other devices that support the technology. KNX has been approved as an international standard (ISO/IEC 14543-3), as well as a European standard (European Committee for Electrotechnical Standardization (CENELEC) EN 50090 and CEN EN 13321-1) and a Chinese standard (Guobiao standards (GB/T) 20965). It was developed to connect devices using twisted pair, radio waves, power line or IP/Ethernet. KNX RF uses a sub-band in the 868-MHz frequency band reserved for short-range devices (i.e., control, telemetry and alarms), supporting bidirectional and peer-to-peer transmissions. 6 LoWPAN and ZigBee provide general purpose, easy-to-use and self-organizing wireless communications for low-cost and low-power embedded devices. Both standards use IEEE 802.15.4 MAC (Medium Access Control) and PHY (Physical) layers, but 6 LoWPAN has been explicitly designed for an easy interaction with IP-based networks. Finally, Z-Wave is a proprietary protocol developed with an explicit focus on home control applications. Since Z-Wave uses a proprietary radio system, it suffers from fewer interoperability problems than ZigBee, but developers are attached to the technology. Generic wireless technologies like Wi-Fi have been proposed as an alternative to specific home automation communication protocols. Thus, the Wi-Fi Alliance has recently approved a new standard for wireless connections called IEEE 802.11 ah or Wi-Fi HaLow[16; 17]. Wi-Fi HaLow extends Wi-Fi into the 900-MHz band, enabling the low power connectivity necessary for applications like the ones that involve the use of sensors or wearables. Wi-Fi HaLow provides robust connections in environments where the ability to penetrate walls and other obstacles is an important requirement. In addition, Wi-Fi HaLow is expected to be backward compatible with Wi-Fi and deliver other benefits, such as multi-vendor interoperability, strong government-grade security and easy setup. Regarding interoperability, the IEEE 1905.1 standard has been recently developed for enabling the convergence of the heterogeneous technologies typically found in digital home networks [18]. Such a standard provides an interface for common home network technologies, allowing for the coexistence of data link and physical layer protocols, such as IEEE 1901 over power lines, Wi-Fi, Ethernet over twisted pair or fiber and Multimedia over Coax Alliance (MoCA) 1.1 over coaxial cables [19]. Cellular communication technologies defined by 3 GPP [20], 4G machine-to-machine communications [21] or Machine Type Communications (MTC) [22] are still emerging. For instance, in [23], the authors analyze the potential of 5G cellular systems for being a key driver in a global IoT, considering both the technological and standardization aspects.