Abstract:
This research paper gives a detailed analysis of EnOcean, an ultra-low-power wireless communication technology that is powered by energy harvesting. Making use of the changes in energy state around sensors like motion, temperature or light intensity change, the device powers itself, thereby minimizing the human interference in maintenance. Taking advantage of the energy efficiency of the model, the EnOcean Alliance is diverting its attention into IoT by offering its energy harvesting wireless modules and aiming to provide a ‘Self-powered IoT’. In this reports, we will explore the merits and limitations of this technology, some case studies, its applications in IoT and also its future scope.
1. History:
Wireless connection technologies like Bluetooth or Wi-Fi have been popular in the cellular phone as well as computer world for a number of years. However, when it comes to power consumption, both technologies are known to use up significant amounts of power. From a point of view of Internet of Things, energy efficiency is a big factor to be taken in consideration while designing a system. Many of the IoT applications require deployment of a sensor network which should be dynamic in nature along with being energy efficient. EnOcean GmbH is the developer of the patented energy harvesting wireless technology. Since 2001, they have been promoting energy harvesting wireless technology and have established intellectual property rights. In March 2012, the EnOcean standard was ratified by the International Electrotechnical Commission (IEC). The main motivation behind the creation of this protocol was to make buildings, home and industrial automation more energy efficient. Later in 2016, EnOcean also launched energy harvesting modules for use in ZigBee and BLE systems.
2. Overview:
The EnOcean standard covers the first three OSI (Open Systems Interconnection) layers, being the physical, data link and networking layers. EnOcean modules aim at combining micro-energy converters with ultra-low power and reliable wireless communications. This helps create self-powered wireless sensor network applications that based on the idea of collecting and processing data in an intelligent system, especially . The specific characteristics of the EnOcean protocol allow highly energy-efficient communication. Dr. Wald Siskens, CEO stated that, “Battery-free wireless sensors will make an entrance into many different areas of our lives. Whether at home, at the office, or during our precious leisure time – everywhere, we find new possibilities of switching things or recording states”.
3. Protocol Details:
3.1. EnOcean Architecture:
The figure below gives a basic idea of the architecture of the protocol. The wireless sensor side of the system is responsible for the acquisition of the data from the sensors. Also, the energy harvesting system resides on that very side. It basically consists of energy converters which generate energy from motion, light and several such parameters. The microcontroller, powered by the generated energy, processes the acquires data, transmits it using a radio frequency transmitter and like mentioned earlier, uses wireless protocols like either EnOcean, ZigBee or BLE. In the wireless system module, an RF receiver is responsible for taking in the data. Further, the microcontroller along with the control unit performs the required actuation.
Fig 1: EnOcean Architecture: Wireless Sensor Solutions powered by Ambient Energy
3.2. Communication:
The EnOcean protocol is in accordance with ISO/IEC 14543-3-1X and ultra-low power specifications of IEEE 802.15.4. It uses 7 bytes of protocol overhead for the transmission of every byte of data that comes from the sensors used. This protocol length is said to be sufficient for wireless transmission of a measured value as far as low power is concerned. The technology makes use of the following regulated frequency ranges: 868 MHz according to R&TTE regulation EN 300220, 902 MHz according to FCC/IC-specification and 928 MHz according to ARIB specification.
EnOcean uses modulation schemes such as ASK (Amplitude Shift Keying) and FSK (Frequency Shift Keying) and transmits data at a rate of 125kbits per second.
This meets the requirements and capabilities for wireless sensors and enables simple deployment of maintenance-free, intelligent nodes.
Long range: up to 30 meters in buildings and 300 meters in free field
One-way and bidirectional communication
Via gateways, EnOcean wireless solutions communicate with all major wired bus systems such as KNX, LON, DALI, BACnet or TCP/IP.
Ultra low power management:
The EnOcean protocol for energy harvesting wireless applications in accordance with ISO/IEC 14543-3-1X and ultra-low power specifications of IEEE 802.15.4 use only 7 bytes of protocol overhead for the transmission of 1 byte of sensor data. This protocol length is sufficient for the wireless transmission of a measured value while it needs very low power only. This meets the requirements and capabilities for wireless sensors and enables simple deployment of maintenance-free, intelligent nodes.
3.3. Energy Harvesting:
Energy from Motion
This principle uses the power of motion to generate energy for wireless signals. When pressing a switch, for example, an electro-mechanical energy converter is activated and uses this movement to generate energy for a telegram. This telegram can turn on/off household appliances, a light or create different scenes for LED lights. The same functionality can be used for a kinetic window contact, which registers if a window is open or closed, or a self-powered water sensor. Here, the energy converter is activated when water gets in touch with the swelling material on the sensor’s bottom. The sensor, positioned below the bathtub or the washing machine, can now send a wireless signal to prevent of water damage.
Energy from Light
Wherever there is light, even at low level of 200 lux or less, tiny solar cells can harvest this source of energy for a broad range of battery-less sensors. This includes temperature sensors, CO2 sensors, occupancy sensors, solar-powered window contacts or humidity sensors.
Energy from Temperature
A temperature difference of already 2 °C delivers enough energy for electronic devices, enabled by the combination of a DC/DC converter and a peltier element. This harvesting technology operates self-powered heating valves, for example, which use the difference in temperature between the heating radiator and the environment to provide energy for changes in stroke as well as for wireless communication with a solar-powered room controller.
4. Advantages:
(COPY-PASTED)Another significant differentiator that sets EnOcean above other potential wireless choices is the use of sub-gigahertz frequencies: 868 MHz in Europe and the Middle East, and 315 MHz in the USA and the Far East. These frequencies are in contrast to wireless systems like those based upon 802.15.4 RF radios, ZigBee and Bluetooth, nestled in the 2.4 GHz band. The lower, more optimal frequencies exhibit lower attenuation through walls and achieve about twice the range for the same transmitting power.
Wireless components can be easily fitted, for little cost, even on surfaces inaccessible for wired solutions.
5. Limitations:
6. Case Study:
7. Citations:
[1] https://www.enocean.com/en/technology/white-papers/
[2] http://embedded-computing.com/articles/no-innovative-wireless-designs/#
[3] https://en.wikipedia.org/wiki/EnOcean
[4] A Comparative Study of Wireless Technologies: Zigbee, Bluetooth LE, Enocean, Wavenis, Insteon and UWB by Ms. Harneet kaur, Ms. Sukesha Sharma. http://www.seekdl.org/nm.php?id=1364
[5] Performance Analysis of the EnOcean Wireless Sensor Network Protocol by Joern Ploennigs, Uwe Ryssel, and Klaus Kabitzsch (Dresden University of Technology, Department for Computer Science, Institute of Applied Computer Science) https://www.researchgate.net/publication/224196856_Performance_analysis_of_the_EnOcean_wireless_sensor_network_protocol
[6] http://www.prnewswire.com/news-releases/enocean-and-self-powered-wireless-technology-2015-report-300035311.html