Develop with LoRa for low-rate, long-range IoT applications

January 10, 2018 // By Rich Miron, Digi-Key
Designers have a wide variety of wireless technologies to connect a product to the Internet of Things (IoT). Each technology suits different applications, requiring designers to carefully consider factors such as range and data rate, cost, power consumption, volume, and form factor. This article will introduce the LoRa protocol, compare its advantages to other protocols, and discuss several products and development kits that enable engineers to get started quickly developing LoRa-based systems.

Wireless IoT tradeoff considerations

Each wireless technology has both strong and weak points. Standard Wi-Fi, for example, can transmit large amounts of data at high speeds, but it has a limited range. A cellular network combines high speed and long range, but it’s power hungry.

IoT applications such as remote data acquisition, urban lighting control, weather monitoring, and agriculture, each have a different set of priorities. The quantities being measured or controlled in these applications such as weather conditions, soil moisture levels, or streetlights, all change very slowly over an extended period of time.

In addition, the sensor nodes are often miles apart and are battery powered, so the optimum wireless protocol must be able to send small data packets efficiently over long distances with minimum power consumption. The LoRa protocol was designed for exactly these requirements.

 

Overview of LoRa technology

LoRa is targeted at low power, wide area network (LPWAN) applications. It has a range of over 15 kilometers, and a capacity of up to 1 million nodes. The combination of low power and long range limits the maximum data rate to 50 kilobits per second (Kbps).

LoRa is a proprietary technology owned and patented by Semtech Corporation, operating in the ISM band. The frequency allocation and regulatory requirements for ISM vary by region (Figure 1). The two most popular frequencies are 868 MHz used in Europe, and 915 MHz used in North America. Other regions, notably Asia, have different requirements.


Figure 1: A comparison of LoRa specifications for Europe and the US, two regions where ISM bands are widely used. (Image source: LoRa Alliance)

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