# Experimental Study of 6 LoPLC for Home Energy Management Systems
## 3 Hanadu 6 LoPLC  
Hanadu is a PLC technology designed by Xsilon Ltd. for connecting Internet of Things (IoT) applications in the home, such as HEMS. Following the preliminary investigations, three units of Hanadu evaluation kits were deployed with a combination of Hanadu and 6 LoWPAN to deliver a 6 LoPLC evaluation platform. Throughout this paper, Hanadu kits and evaluation kits shall be used interchangeably. Although, Hanadu kits employ 0-32 MHz, which is within the Broadband PLC (BPLC) spectrum, in contrast with the conventional BPLC system, it is being investigated for low-rate in-home control applications, such as smart lighting, sensing, etc. Hanadu is based on Orthogonal Frequency-Division Multiplexing (OFDM), and the tone map is such that the 32-MHz spectrum is divided into 128 sub-carriers. Each sub-carrier occupies a bandwidth of 250 kHz, such that if divided into five bands, approximately half the energy is contained in the middle band. Hence, for each carrier, the centre frequency is:  
\[f_{c}=\frac{(f_{l}+f_{h})}{2}, \tag{1}\]  
where \(f_{l}\) is the lower frequency bound and \(f_{h}\) is the upper frequency bound. To avoid interference with nearby radio transmissions and reduce inter symbol interference, only 86 channels are utilised, notching out broadcast and amateur radio frequencies (e.g., 28-29.875 MHz). The test bed used for evaluating the 6 LoPLC consists of three types of entities: lighting, communication system and application. While the lighting is made of an Light-Emitting Diode (LED) fixture powered by 24 V DC, the Hanadu 6 LoPLC units provide the communication system to convey control signals from the HEMS controller to the lamp and response in the opposite direction. In terms of application, the lighting and sensing applications are based on Constrained Application Protocol (CoAP)--published by International Engineering Task Force (IETF) in Request for Comments (RFC) 7252. The architecture is such that the CoAP client is installed on the HEMS controller while the server is installed on the nodes (lamp and sensor). The CoAP client provides the mechanism for sending control commands and monitoring requests. For example, the CoAP client can request from the nodes the energy consumed by the device connected to their attached sockets and can also send the control signal to alter the luminance of the LED lamp over the power line network. In the case of the sensor, the client can request the ambient temperature from the sensor and receive temperature as part of the response. In both cases of the sensor and lamp, the CoAP server communicates with the respective engines through Universal Asynchronous Receiver/Transmitter (UART) commands, as shown in Figure 0(b). Therefore, the role of the CoAP application is to provide an embedded web interface to interactively send control signals and receive measurements from the nodes. A simple setup of the Hanadu 6 LoPLC test bench is shown in Figure 1.  
The protocol mapping between Transmission Control Protocol (TCP)/Internet Protocol (IP) suite and the implemented model, which includes 6 LoPLC as the adaptation layer in accordance with RFC 2460 [33], is illustrated in Figure 2.  
As seen in Figure 2, with reference to LoWPAN (802.15.4), Hanadu retains the 802.15.4 Media Access Control (MAC) sublayer and replaces the PHY with the 2-30-MHz power line PHY, thus transforming it into a PLC system. The CoAP was developed by IETF for resource-constrained nodes and networks (RFC 7251), such as the sensor and lamp with a low-rate discussed in this paper. Due to the high communication overhead associated with Hypertext Transfer Protocol (HTTP), CoAP was developed to offer web services similar to HTTP, but with lower overhead by employing an asynchronous message exchange that relies on a data-oriented transport protocol. The Hanadu evaluation kits and simulations are based on User Datagram Protocol (UDP), since CoAP natively supports it.