Zigbee signal strength

Been seeing some drop outs on my zigbee setup for a group of devices I have in my garage. The garage is about 8-10m from the house and I have samsung plugs (repeater) in both the house and garage with the best possible line of sight. On ST these have been working fine in the present locations for about a year. But since moving over to HE I have seen them drop off regularly. When monitoring the zigbee events I was seeing the the rssi was generally above 90 (not good).

Lastnight I tried moving the hub around and eventually moved it back to where the ST bug was previsously (had moved it closer to P3 (see below)) and added another samsung plug. With this new setupo I have an rssi in the low 80s. Things seem to be working ok so far.

My setup looks something like this:

HE     |                                          |----|porch
       |                            P2            |P3   |
-------|                         -----------------|_____!                        |---------------|
     P1|                      |        stairs     |                              |P4             |
       |--                 ---------------------- |                              |   garage      |

I am sure there are easier ways to do draw that (but anyway). Hub (HE) is about 1 meters from P1 and goes through a single skin brick wall. P1 is about 3m from P2 and goes through one brick wall. P2 is about 2m from P3 (one brick wall )and as I already said P3 is about 8-10 m from P4.

So the repeater I added was P2 and to be honest I would not have expected to need this with it being relatively close to P3 .

Anyway, my question is this. What values do others see from the zigbee strength. Is low 80 comparable? It just seems strange because this worked fine on ST, I would not expect to need 4 repeaters to cover a distance of less than 20m.

Not sure if it makes a difference but I am in UK, so have zigbee and zwave on 2 separate usb sticks.

Wow that did not look at all - had to use pre tags.

Do you know the old and new Zigbee channels? AKA what was the channel on the ST platform and what channel on HE?

I meant to put that in my post. I am on channel 15 now and was on 14 on ST. I looked into it and current wisdom is that 15,20 are better channels as they sit between the 2.4 mhz wifi channels. When the hub set itself up (if I recall correctly) it was on channel 26, Which when I read about it, said was a weaker channel.

Food for thought:

However, our results in experiment two and three show a high percentage of packet error rates
on the edge channels whereas the channels that are close to the center frequency have a lower


Edit: I could find NO collaborative reference that Channel 26 transmits at a lesser power rate and is hence a weaker channel from a transmission perspective.

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Any chance to have P3 and P4 out the brick walls?

I had a similar situation and after I put the plug in a glass window problem was solved. Maybe you need an Xbee, they are great repeaters with a lot of power.

Another thing is, did you disconnected HE hub for at least 15 minutes to make the mesh repair? Maybe you garage is not connected to your nearest repeater, because you added P2 and then the garage got better signal.

So after reading that I feel i should either revert to 26 or pick the channel bang in the middle of the quietest wif i channel. Thank you for the paper, was a good read.

Vjv, genious! I will try that. Will also look into xbee. What's rssi values do you have?

The worst rssi I seen here is 70, but most of the time is between 50s and 60s. By the way, I use channel 25, I think I read somewhere that 26 some devices don't like it, but not sure if that theory is correct.

Good luck.

I have ST presence sensors in my cars (sitting on the drive) and regularly get 40-45 from all three.
I think the best thing I did was put an xbee in the bedroom window above the drive.

If I disconnect this and replace it with an ST socket in the same place then the signal drops significantly.

Since I put two xbees in (one upstairs and one down) I have had no signal problems at all from any of my devices (Using channel 21)
The other advantage is that with the xbee I can obviously map the zigbee network too.
I think they are brilliant!


Do you keep the Xbee connected to a computer at all times? Or, do you mean that you can map the network......if you wish?

Both actually,
I bought a 3rd one just for mapping..
It’s connected most of the time so I can map whenever I want.


Xbee seems like the way forward but there are lots of variants and stock problems. Taking a look around to see what's available in uk. Will report back.

I have a fair amount of repeaters, but my RSSI values all seem to be very high (or low, depending on how you define it). Some of these devices are within 20 feet of the hub. Is this bad? The only ones I have problems with are the Garage Bulb sometimes, and the Driveway Light, but those have an RSSI even better than some that are much closer to the hub. I'm on Zigbee channel 25. WiFi is below, channel 1.

These values are not from the hub necessarily. They are from it's hop from the device to it's nearest repeater. Zigbee is capable of optimization in routes automatically (no manual repair) so the values can change as this occurs. If the lqi is 255, which means no or low noise, and the rssi is under -90 (closer to 0 is better) you are good.

Good to know, thanks. Regarding LQI, most seem to be 255, but some are lower. Is anything below 255 representative of more noise?

How do you view the signal strength of Zigbee devices?

Yes. Lower lqi means noise between the nearest repeater and device.

Settings --> Zigbee Information --> Zigbee Logging

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Thanks for the info, I was thinking that -70 was a little bad.