Hello and welcome to another episode of “Learn Technology in 5-minutes from MAKERDEMY.

In this video, we will learn about LoRa, the low power wide area network technology for the Internet of Things. You are familiar with Wide Area Network technology like the cellular 4G and 5G which allow data transmission over long distances. However, cellular WAN consumes a lot of power. How often do you charge your mobile phone? I charge my phone every day. Cellular WAN allows us to transmit large amounts of data at high speeds over long distances. The trade-off here is high power consumption. Now let us think of an IoT solution wherein we have wireless sensor nodes spread over a few kilometers to transmit their sensor values via a network a few times every hour. Furthermore, these nodes operate on batteries that are supposed to run at least for a couple of years. These nodes can’t be mains charged like your mobile phone. The data transmitted will be small and sporadic. Under such conditions, we need a wireless network that consumes very low power but also operates over distances larger than those of say, WiFi. Is such a network even possible? Enter LoRa. LoRa is an abbreviation of LongRange. Let’s first get some confusion related to terminology out of our way. There is LoRa and there is LoRaWAN. LoRa is a proprietary radio modulation technology owned by Semtech and deals with only the Physical layer of the stack. The LoRa technology uses a proprietary Chirp Spread Spectrum modulation technology that makes the low power long-range transmission possible over the unlicensed ISM band. Semtech has licensed the LoRa technology to several vendors who produce LoRa devices. In contrast, the LoRaWAN is the communication protocol and system architecture for the network. The LoRaWAN deals with the MAC layer and application layer of the LoRa protocol stack and is open source and is managed by the LoRa Alliance, a non-profit association of over 500 companies that is responsible for the development and promotion of the LoRAWAN open standard.

The LoRa operates in the unlicensed ISM band in the sub-Giga Hertz frequency. This means that you do not need any license to transmit data via the LoRa technology. The actual frequency of this sub-Giga Hertz ISM band for LoRa varies from country to country. You can find out what the frequency band in which LoRa network operates in your country by clicking on this link. For example, in India, it is 865-867 MHz.

To get some perspective, let us take a look at this chart, which compares several wireless technologies on 2 dimensions - transmission range and the bit rate. As you can see, the LoRa bit rate is quite low...it is in the order of tens of kilobits per second. But this comes with a much larger transmission range and much lower transmission power.

In a LoRaWAN network, we have the LoRa nodes and the LoRa gateways. LoRa nodes are devices with the LoRa radio modulation capability along with sensors and microcontrollers. The LoRa nodes typically run on batteries that are expected to run for several years. Several LoRa nodes connect to LoRa gateways, which channel the data from the nodes to a network server and from then on the data is moved to a variety of application servers. In LoRaWan, The LoRa nodes to gateway connection are in the form of a star network and the nodes cannot talk to each other directly. Also, the communication between the gateway and the nodes is bidirectional, so that we can also get the nodes to perform some actuations like turning on some status lights and so on. Each node can transmit to multiple gateways and the network server removes the duplicates and forwards the appropriate data from the node to the correct application server.

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