How can I wirelessly deliver ~30B of data to ~10 peripherals roughly every 50ms?

Question

I am thinking of a system where 10 or so peripherals need to receive 30-50B of data every 50-ish milliseconds (each peripheral gets unique data). The total throughput required might not be huge (6-10kB/s) but the problem lays in the number of devices which need to receive the data.

I've looked into using BLE but even though the total throughput lies well within the maximum possible ~35kB/s, what I want is not possible due to the hard limit of 20ms Connection Intervals. Another solution I considered is using a simple RF transmitter and RF receivers which all listen to it simultaneously. I'd have to manually take care of error correction etc but I would not have to worry about switching between the receivers which takes precious time. A problem with that would also include the inability to have two of such systems deployed near one another without the risk of the transmitters talking over one another.

So what other solutions are available to me?

Answer 1

I suspect that using nRF24L01+ transceivers would solve this for you. Theoretically good for 1 or 2Mbps, less acknowledgements and some packet overhead and you should still be able to sustain over 100kbps of user data without any dramatic effort.

Answer 2

You could take a look at the IEEE 802.15.4 protocol. There are lots of transceivers out there. This would allow you to transmit all device data for all peripherals in one packet every 50ms (on air time for a packet like this will be <1ms). Assuming that you don't need a mesh network, this could work nicely for you and minimize latency.

IEEE 802.15.4 radios use CDMA, so they will not stomp on each other when transmitting in the same RF space.

Without a mesh network, you'd be running a star configuration with the "master" at the center of the hub and your peripherals acting as points on your star.

Good luck - sounds like a fun project.

Answer 3

Get a simple 433 MHz transmitter and a few of receivers, send a data preamble, then an address then the data then a couple of byte CRC. If you need to send data to specific receivers then embed address and data into one long stream intersperced with CRCs so that the right receiver knows what it's looking for. In other words develop a simple protocol and buy some cheap TX and RX and you should be in business. 433 MHz may not be allowed in your country but there will be a frequency that is.