ZWave versus WIFI with obstructions

I have a very solid rock wall in my backyard that my switch unfortunately needs to be behind. Right now I have a Wemo switch back there which works well. I need to add another switch and my zwave devices seem to struggle. Is there a logical reason why wifi seems to work there and zwave does not?

I can put another switch further past the wall before the next one if that would help ie. go past the switch behind the wall to one further out in the hopes the repeater would bounce back. Or I could just get another wemo switch but I hate doing that given im trying to standardize on Zwave+

The wemo switch is directly behind the rock wall where the yellow arrow is. A zwave switch there is non-communitive. The Hubitat and Google wifi are both inside and close to each other right behind where I took the picture about 7ā€ high so slightly above the wall.

Someone with radio engineering experience can likely correct my thoughts.

However, my guess is that part of the issue relates to the frequencies of the Wi-Fi vs. Z-Wave.

You might try a line-powered Z-Wave device or a repeater that will "repeat" the signal that has "line of sight" to the house and to your hidden device--without going through the brick wall.

There are several logical reasons.

  1. Max transmit power of Zwave + is 13dBm. Max transmit power of WiFi is 20 dBm. (31 mW to 100mW).

  2. The wavelength of a 908 MHz Zwave+ signal and a 2.4GHz signal are vastly different (let alone the wavelength of a 5 GHz signal). So penetration of the stone, multipathing off nearby objects, interference, etc may all be different yielding different results.

  3. The fundamental protocols are different. TCP/IP over WiFi is a complex protocol with a variety of techniques to overcome packet loss and errors. Zwave+ is much lower date rate, and meant to be simpler. I'm not sure how it compares with WiFI and TCP/IP, in detail, but given the extremely low data rate and simple modulation, I expect it has less in the way of error correction or compensation.

A Zigbee device might have a better chance in the same location from a frequency perspective, but in truth I think you're just going to have to experiment and see what works. Might even been the specific device you are using has an unusually weak antenna, or is significantly more sensitive to loss/interference than another device.

Frankly RF at short range is pretty much black magic to me...lol...good luck though.

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Thanks guys. Iā€™m going to try and get zwave to work. These are all line powered devices fortunately so Iā€™m going to put one past it on the hill (there is a retaining wall about 6ft behind the rock wall and see if that can reflect back to the switch that is immediately behind the rock wall. While the wemo works remarkably well, I hate to keep expanding that set of devices, up until zwave drives me nuts (another weekend;)

Good idea. Good luck!

S

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