Low latency, high channel period wireless protocols

Question

I was wondering if anyone can suggest any low latency high channel period wireless protocols or devices.

I have been using the ANT and xbee chips to sample a digital signal however their channel periods are too long for my application.

The xbee takes at best ~50ms for the data to be received, whilst the ANT takes ~7.5ms at a 256hz channel period.

I would like to know if anyone knows of any device/ protocol that has a channel period of 500khz or higher preferably above 1000khz to be able to receive within 5ms consistently as at worst the ANT takes ~15ms

Cheers

Answer 1

The IEEE 802.11 protocol (Wi-Fi) can support lower latency, but you may find that common implementations will not be much lower than a few milliseconds. Latency is a function of delay to access the channel, packet length, and the delay through the protocol stack. If only one device is transmitting on the channel, the channel access delay will be less than 100 microseconds. 802.11 also supports packet lengths that are less than 100 microseconds. So, if you can find the right implementation, you might be able to set the parameters to achieve a total latency of a millisecond or so.

Answer 2

Direct single carrier transmission can have very low delay, you may need to use licensed spectrum to cover any appreciable distance.

Free band 433Mhz garage door openers often send data at 380us per bit. If you can have a continuous signal carrier then you are covered. If you need some protocol headers it will be slower.

If you have more power, better/directional antenna, less data, no QRM and higher bit rate (using say 2.4GHz band) you can improve on it a lot.

Need more information to determine if you even need a spread spectrum or protocol intensive solution.