[SOLVED] Local Area Network with 100 nodes: wireless protocol selection

Hi,

For an upcoming project, I need to be able to connect around 100 devices wirelessly to a gateway. The area is indoor and the size of an average movie theater room. All devices should be connected (pseudo)simultaneously, but the packet size is very small (few dozens of bytes per second). I'm still unsure about the best wireless technology to use in this application. Cost is the primary limiting factor, but it also needs to be low power (running from a tiny battery).

Wifi seems to be overkill, because it drains the battery too fast (excessive transmission power and bandwidth I don't need). A possible candidate would be BLE, but since BLE only supports ca. 35 channels, I fear that this would cause constant channel hopping by all the devices, leading to immediate fatal congestion. Will this indeed be a problem? Or may BLE be able to handle 100 devices simultaneously at low data throughput? Which other alternatives could be considered?

Thanks in advance for your thoughts!

Try to view at IEEE 802.15.4 standard for low-power applications, in particular ZigBee. ZigBee is well-suited for such networks.

I had considered Zigbee before, but according to the official spec there are only 16 channels defined for IEEE 802.15.4, as opposed to 35 for BLE. Doesn't this mean the congestion problem will be worse for Zigbee in comparison to BLE?

In theory ZigBee allows up to 65k devices within one subnet (16-bit addressing), in practise you'll be able to run 500-1000 nodes depending on your demands. But 100 nodes is not a problem for ZigBee.
There are other protocols similar to ZigBee, such as 6LoWPAN, Z-Wave etc. They were developed for low-power, low data rate, large amount of nodes, so you can consider them also.
BLE has limitations for the number of slave devices depending on hardware chip, but in any case it can maintain much less connections compared to mentioned protocols.

We'll take a look at ZigBee and 6LoWPAN as probable candidates, thanks for sharing your thoughts!