In IoT Hacks series #6 blog, you had a chance to read about the LoRaWAN protocol. Today, more about LoRa, the heart of this solution.
It’s been 12 years since the idea of making LoRa as a robust and low-power radio link became one of the most popular technologies in the IoT world. Its modulation techniques were inspired by the way that dolphins and bats use on daily basis to communicate and find their way through obstacles. The Chirp Spread Spectrum modulation used in LoRa communication proved its reliability in such appliances as sonars and radars many years before the IoT boom. In 2012 the first LoRa chip was released by Semtech company and became a strong competition to all the RF chips available before. To keep the standard clean and clear the LoRa Alliance – a non-profit organization was founded.
The rapid growth of the IoT market pushed it even further – extremely low power consumption, high level of security, long-range, and ease of use made the LoRa a leading technology used in transportation, smart metering, and smart-city applications.
In a few years since the first chip announcement, the LoRa physical layer was stocked up with the robust and secure LPWAN protocol (low-power, wide-area network) called LoRaWAN. The main drawback of the LoRa was an inability to communicate with mobile devices, such as smartphones, which could be used for configuration, and service routines like firmware updates due to the low ISM bands (433MHz, 868MHz, 915MHz) that LoRa operates on and smart devices don’t.
In 2017 LoRa found a new space in the 2.4GHZ ISM band to solve this issue. The Semtech company announced the SX128x chip series that can operate on a well-known 2.4GHz band sharing both LoRa and Bluetooth Low Energy on the same radio hardware. Combining two of the most popular IoT technologies made an almost perfect solution for standard IoT cases keeping the benefits of both worlds – long range and robustness of the LoRa communication and interoperability with smart devices through the BLE.
Standard LoRa 2.4GHz operates on four selected channels to minimize interference between Bluetooth Low Energy and WiFi. Three Join/Transmit channels (2403MHz, 2425MHz, 2479MHz) and one Receive channel (2423MHz) are available in end-node devices. The bandwidth of each channel has been increased to 812.5kHz from 500kHz in the lower ISM bands, and the bandwidth occupancy limit, which previously ranged from 0.1% – 1% for transmissions from the device to the gateway (uplink), has been completely removed. As a result, real-time process monitoring and seamless wireless updates are possible (On The Air Update). Since the technology lacks the ‘duty-cycle limitation’ and has a significant bandwidth increase from around 5.5kbps to 253.91kbps, LoRa communication can be utilized in projects previously prohibited by these factors. Will the LoRa 2.4GHz take over the IoT world? Presumably YES – as always the market will reveal.
Rafał Ziębiński, embedded systems designer with years of experience in the medical, industrial, and consumer industries. Passionate about solving development problems where hardware and software meet.
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