Long Range Wide Area Network
Long Range Wide Area Network ( LoRaWAN ) is a low-power wireless - network protocol . The LoRaWAN specification is set by the LoRa Alliance. It is freely available and uses a proprietary and patented transmission method based on chirp spread spectrum - modulation technique , called "LoRa" the company Semtech . Basic modules are available as open source software .
LoRaWAN is asymmetrical and geared towards energy efficiency for ranges of over 10 km for uplink communication, i.e. sending from the end device to the network. The data transfer rate ranges from 292 bit / s to 50 kbit / s. Various levels of operation up to quasi-continuous downlink communication are possible - the latter comes at the expense of energy efficiency. (In view of the physical characteristics - transmission in the low frequency range with low energy consumption - the " LoRa " can also be read or understood as "low radiation". The LoRa Alliance, for example, also speaks of Low Power Wide Area Networks .)
construction
The network architecture is star-shaped . Terminal devices communicate with gateways , which send the data packets to a server. This server has interfaces for IoT platforms and applications.
LoRaWAN uses regionally different frequency ranges in the ISM band and SRD band , including in Europe the frequency band from 433.05 to 434.79 MHz (ISM band region 1) and from 863 to 870 MHz ( SRD band Europe). In North America, the frequency band from 902 to 928 MHz (ISM band Region 2) is approved for this.
The ranges extend from 2 km in urban areas to 40 km in rural areas. The building penetration is a great advantage, as basements can also be reached. The power requirement in end devices is around 10 mA and 100 nA in sleep mode. If self-discharge is neglected, this enables a battery life of 2 to 15 years. The communication between the end device and the gateway takes place on different frequency channels with data rates from 0.3 to 50 kbit / s.
The frequency spread enables high efficiency in data transfer and energy consumption. This minimizes interference. The network server adjusts the data transfer rate to the end device as required (ADR = Adaptive Data Rate). Communication in LoRaWAN is encrypted twice with 128 bit AES , on the one hand to the network server and on the other to the application server.
Available LoRaWAN networks
The Netherlands , Switzerland and South Korea are the first countries to offer comprehensive LoRaWAN coverage. In Switzerland , Swisscom operates an LPN in the 863 to 870 MHz frequency band ( SRD band Europe). The gateways of the Swisscom LPN transmit with up to 500 mW transmission power (27 dBm ).
South Korea 's largest telecommunications provider SK Telecom introduced a nationwide Low-Power Wide-Area Network ( LPWAN ) for an IoT infrastructure in July 2016 . The Dutch KPN also provides an IoT network with LoRa technology across the country. The Dutch initiative The Things Network (TTN) has been following an international, community- based approach since 2015. To date, it has been established in over 137 countries and in over 700 communities. Around 10,000 LoRaWAN gateways are active there. The leading locations are Zurich , Bern , Amsterdam and Berlin . In Germany, more than 1100 gateways are installed in over 100 cities and towns. Most of the world's installations in a large city are found in Berlin. There, 106 IoT gateways were connected to a fully usable, city-wide network in 24 months. Its use is free of charge and does not require permission.
Bidirectional variants of the end devices
Class a
Communication works according to the ALOHA access procedure. The device sends its generated data packets to the gateway, followed by two Download Receive windows that can be used to receive data. A new data transfer can only be initiated by the terminal with a new upload.
class B
Class B terminals open the Download Receive window at specified times. To do this, the end device receives a time-controlled beacon signal from the gateway. In this way, the network server knows when the end device is ready to receive data.
Class C
Class C terminals have a permanently open download / receive window. Class C devices are therefore almost permanently active.
Web links
- General allocation of frequencies with a short range, Federal Network Agency Order No. 5/2018
- LoRa Alliance
- Swisscom LoRa network
- The Things Network (TTN)
Individual evidence
- ↑ Patent US7791415B2 : Fractional-N synthesized chirp generator. Filed May 16, 2008 , published September 7, 2010 , applicant: Semtech Corp, inventor: Craig A. Hornbuckle.
- ↑ Michael Eckstein: LoRa IoT software is becoming open source - at least in part. Elektronikpraxis, May 3, 2019, accessed May 26, 2019 .
- ↑ https://docs.wixstatic.com/ugd/eccc1a_ed71ea1cd969417493c74e4a13c55685.pdf LoRa Alliance - What is LoRaWAN
- ↑ https://docs.wixstatic.com/ugd/eccc1a_20fe760334f84a9788c5b11820281bd0.pdf LoRa Alliance - LoRaWAN 101 - A Technical Introduction
- ^ Graeme Burton: Netherlands beats South Korea in rolling out national Internet of Things network. Computing, July 1, 2016, accessed July 4, 2016 .
- ↑ https://www.swisscom.ch/de/about/medien/press-releases/2015/03/20150312-MM-SCS-testet-Netz.html Swisscom - Media release - Swisscom tests network for the Internet of Things - 12 March 2015
- ^ Oh Chan-jong: SK Telecom leads in IoT race, completing nationwide network. PulseNews, July 4, 2016, accessed July 4, 2016 .
- ^ Gerhard Peter: TTN Community Berlin. TheThingsNetwork, February 12, 2018, accessed February 12, 2018 .