LPWA, LoRa, LoRaWAN
LPWA (Low Power Wide Area)
LPWA is a generic term for a group of wireless communication technologies with the following key characteristics:
- Low power consumption:
- end devices (e.g.: sensors) are usually powered by batteries with 15+ years of battery life time
- Wide area connectivity characteristics:
- the maximum distance between the ends of the wireless links is more than 15 km
- the infrastructure can easily scale at a size of a country
- Low cost of network components and cheap end-devices
- Data communications throughput capacity is usually less than 10 kbps.
LoRa (Long Range Radio)
LoRa™ is a wireless spread spectrum data modulation technique developed by Semtech for LPWA communication. LoRa™ has the following key characteristics:
- Applies CSS (Chirp Spread Spectrum) modulation in 125 kHz channels.
The modulated signal can be generated by Semtech LoRa parts, including the SX1272 and SX1276 transceiver chips.
- Operates in unlicensed sub GHz frequencies that are available worldwide. The most widely used frequencies / bands are:
- 868 MHz for Europe
- 915 MHz for North America
- 920 and 433 MHz band for Asia
- Provides long range coverage
The LoRa modulation allows coverage over a range of 2 to 5 km in dense city areas and up to 15 km for countryside applications.
LoRaWAN (LoRa Wide Area Network)
LoRaWAN™ is an open global standard for secure, carrier-grade IoT LPWA connectivity defined by the LoRa Alliance. The LoRa Alliance is the fastest growing alliance in the IoT industry having 400+ members. The founding members were Semtech, IBM and Actility.
The LoRaWAN™ infrastructure has the following key characteristics:
- Star Topology
LoRaWAN™ network architecture is typically laid out in a star-of-stars topology in which gateways is a transparent bridge relaying messages between end-devices and a central network server in the backend. Gateways are connected to the network server via standard IP connections while end-devices use single-hop wireless communication to one or many gateways.
- LoRa RF modulation
The LoRa™ RF modulation is used as the physical layer of the connectivity between devices and gateways.
- Bi-directional communication
The radio technology used by our sensors is fully bi-directional. It supports both monitoring and remote triggering of sensors and therefore covers a wider range of innovative IoT applications.
- Adaptive Data Rate (ADR)
ADR is the procedure by which the network instructs a end device to perform a rate adaptation by using a requested Data Rate and TX Power. One of the major purposes of this feature is to reduce the device battery draining while ensuring satisfactory quality and boosting the link budget.
- Low Device Energy Consumption
The LoRaWAN infrastructure supports low-power sensors requiring less than 15mA which cannot be covered using traditional short range wireless networks or traditional ISM technologies.
- Three different types of device classes
LoRaWAN defines 3 different classes of end-point devices to address the different needs reflected in the wide range of applications:
- Bi-directional end-devices (Class A):
End-devices of Class A allow for bi-directional communications whereby each end-device's uplink transmission is followed by two short downlink receive windows. The transmission slot scheduled by the end-device is based on its own communication needs with a small variation based on a random time basis. This Class A operation is the lowest power end-device system for applications that only require downlink communication from the server shortly after the end-device has sent an uplink transmission. Downlink communications from the server at any other time will have to wait until the next scheduled uplink.
- Bi-directional end-devices with scheduled receive slots (Class B):
In addition to the Class A random receive windows, Class B devices open extra receive windows at scheduled times. In order for the End-device to open its receive window at the scheduled time it receives a time synchronized beacon from the gateway. This allows the server to know when the end-device is listening.
- Bi-directional end-devices with maximal receive slots (Class C):
End-devices of Class C have nearly continuously open receive windows, only closed when transmitting.
- Bi-directional end-devices (Class A):
- Security at application and network levels
LoRaWAN network architecture offers end-to-end network security. Message payloads between end-devices and the network server are encrypted by Application Session Keys while the integrity of protocol commands and signalling are ensured by a hash mechanism based on Network Session Keys. This security is applicable even in a multi-vendor environment assuming that every component have passed the LoRaWAN/Thinkpark certification tests.
- Location based services
Time difference of arrival (TDOA) based localization is based on precise measurements of packet arrival time differences on different base stations. It does not require specific capabilities in the mobile node, such as a GPS, dramatically reducing its cost and power consumption.
LoRaWAN base stations are GPS synchronized and support TDOA localization with ~50m accuracy for 125kHz spread-spectrum nodes even in urban multipath environments for fixed or mobile objects.
- Open standard (ensuring Device Interoperability)
ThingPark Wireless is based on the LoRaWAN™ standard which provides seamless interoperability among smart things without the need of complex local installations and gives back the freedom to users, developers and businesses to roll out IoT solutions.
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