IoT(Internet Of Things)

  

 

 

 

LPWAN - LoRa    

 

LoRa is a kind of LPWAN (Low Power Wide Area Network). I am not sure exactly where the word LoRa came from.. but many say "the name LoRa came from Long range low power Radio Network". As mentioned, this is a kind of WAN (Wide Area Network), meaning it would have relatively wide coverage. To provide the wide coverage, it forms a kind of network system which is similar to cellular network. As you see in the following illustration, it has a small central access unit called LoRa Gateway (this is similar to Basestation in cellular system). Around the Gateway are many devices called LoRa end node (this is like a mobile phones). Each of these end unit communicate with a Gateway and the Gateway conveys the user data between the end Unit and Network Server (this is like a core network in cellular system).

Followings are some of the fundamental features of LoRa System.

  • LoRa uses the radio frequecy in ISM Bands under 1 Ghz. The specific frequeny varies depending on region
  • LoRa uses a kind of Spread Spectrum technology in terms of modulation.
  • Transmission Power of the end node may varies but it can transmit up to 20 dBm
  • LoRa can achieve the data rate between 300 bytes and 100 kbps and the data rate can be changed dynamically by the mechnism called ADR (Adaptive Data Rate).
  • LoRa is basically Uplink (from end device to Gateway), but it terms of specification it supports both Uplink and Downlink
  • Single Gateway is claimed to handle up to 60,000 end points but it mainly depends on how much data each of the end units transmits.
  • The coverage of single LoRa Gateway is generally around several killometers, but it is claimed to cover up to 45 km. However, this coverage may vary depending on communication environment.
  • If you want to implement RoLa, you have to setup everything (end device, Gateway, Network Server). Somebody say this is a kind of drawbacks of LoRa because you have to do everything, but somebody says this is an advantage of LoRa since you can have full control over every components of the whole network.

 

 

In Jul 2017, SKT (a Network Operator in South Korea) deployed the nation wide IoT network based on LoRa. The overall network configuration is as follows (This illustration is based on a presentation in Ref [6])

 

 

Reference :

 

[1] Samtech LoRa FAQ

[2] LoRa® Technology 

[3] LoRa Specification - 2015 LoRa Alliance, Inc

[4] Talktime: Ronan Schwarz – Internet of Things with LoRa (YouTube)

[5] T Dev Forum. 06 LPWA Technology and Development Trend (YouTube, in Korean)

[6] T dev forum - IoT N/W (LoRa etc)  (YouTube, in Korean)

[7] #112 LoRa / LoRaWAN De-Mystified / Tutorial

[8] #115 How to build a LoRa / LoraWAN Gateway and connect it to TTN? Using an IC880a Board

[9] #117 DIY LoRa Node with Arduino and Dragino Shield connected to TTN LoRaWAN  

[10] #124 Cheap LoRa Gateway: How to Build with one with Raspberry Pi and Dragino