Sending a wireless message simultaneously from a gateway to lots of low power IoT devices should be a no-brainer, but for many networking technologies, it is brutally difficult or just impossible.
Some networking stacks can’t even try: battery powered LoRaWAN and Sigfox endpoints the easiest examples. Other protocols do it one endpoint at a time — 6lowPAN is one example — but that really isn’t broadcast, is it?
When do low power IoT networks need broadcast (messaging simultaneously to all devices in range) or multicast (messaging to multiple devices, but perhaps not all, devices in range) capability? Here are three quick examples:
- Location Queries. Asking for the locations of a each cow in a herd of 500 cows. Or each shipping container in a yard. If you want real-time results, you’ll want a way to broadcast your query to everyone in real time.
- Implementing GPS. We recommend the use of assisted GPS (A-GPS) when deploying GPS over a LPWAN endpoint. It’s definitely possible to do it without A-GPS, but the battery savings and performance boost using A-GPS is material.
- Firmware Updates. The soft, white underbelly of today’s IoT is over-the-air (OTA) firmware updates, where so many devices are difficult to patch wirelessly or just don’t support OTA updates at all. (Shoulder shrugging is not a solution …) And no one wants to update endpoint firmware with a USB cable.
There are more use cases for broadcast, but these are good for starters.
<a href="https://medium.com/media/a6acf2885d113937f6f42fc90b062d93/href">https://medium.com/media/a6acf2885d113937f6f42fc90b062d93/href</a>
We are implementing queries to some battery-powered LoRa devices running Haystack + DASH7 using the popular MQTT publish-subscribe application. MQTT is not typically used for queries, but with the compression capabilities of Common Business Object Representation (CBOR), it is possible to do it with Haystack + DASH7 with good results.