Zigbee and Wi-Fi

zigbee
wifi

(Paul Ockenden) #1

Thought others might find this interesting - it’s a scan of my local 2.4GHz space. Wi-Fi channel numbers along the bottom (very small, hard to read - sorry!):

The red (strong) spike around channel 9 is the SmartThings Zigbee (using Zigbee channel 20). Because you can’t change that, I’ve deliberately moved my Wi-Fi well away (it’s the lump that centers on channel 1). The other lump around channel 6 is my Arlo camera network. The only reason it looks so huge is because the base station is right next to my laptop.

The other green spike is the Zigbee used by the Microinverters on my solar panels.

It’s a real shame the SmartThings Zigbee channel isn’t right at one or other end of the 2.4GHz band, rather than (in my case) being quite near the middle. It would make it easier to avoid clashes with Wi-Fi networks.


( I hate Mondays) #2

What app did you use to produce the graph please? Any other custom electronics required?


#3

Different individual SmartThings hubs are using different zigbee channels.

For the V1 hub, it was fixed at the time of manufacture and you couldn’t change it at all.

For the V2 hub, every time you do a full factory reset the zigbee channel gets reassigned randomly, but it might even reassign the one you just had, and you don’t get to specify what it should change to.

So if you’re willing to do a complete reset, you can just keep doing it until you get the zigbee channel where you want it to be. Good to know if you’re doing a complete rebuild, but otherwise probably not too useful.

But the main point is that where your ST zigbee transmission is might be very different from where another SmartThings hub is.


(Paul Ockenden) #4

I’ve often heard it said that the V2 hub picks a channel at boot time, but I don’t believe it’s true. If I sit an AP next to mine, blasting away on channel 9 it still boots with ZigBee channel 20 every time. Even if I do a full reset. I’ve done that several times now,

Has anyone ever actually seen their ZigBee channel change?

As for tools, I’m a long time supporter of metageek’s wi-spy tools, and wrote one of the first reviews of their stuff. In this instance I was using the tiny dongle that comes with inSSIDer Office. http://www.metageek.com/products/inssider/


#5

@slagle has said that it will, but you can’t just reboot, you have to do a full factory reset. Otherwise it would change every time you took it off power, which it definitely doesn’t. Factory reset requires removing the location all together.


(Paul Ockenden) #6

So that’s pretty much never going to happen in the real world then. For all intents and purposes the ZigBee channel is fixed.

I can’t see people wanting to effectively trash their complete SmartThings setup to get a different channel. Even if it does work (anyone care to volunteer to try?)


#7

It’s fixed for hub V1. For hub v two, if you know that you have that option and you’re setting up a brand-new hub, you might want to repeat the process a couple of times in order to get your preferred zigbee channel. So I can see people doing it in some situations.

But it’s certainly not something that someone with an established account is likely to want to do unless they run into some major issue like a new neighbor with Wi-Fi on a new channel causing a lot of problems.


(Mark) #8

I still have a v1 hub setup but will probably upgrade to a v2 hub in a few weeks, might move it around a little, etc. I’ve only used the free version of inssider before. Does the ST hub report which zigbee channel it’s using or do I have to use dedicated software to get this kind of spectrum analysis?


#9

It’s in the IDE under the hub information. The exact instructions are in the thread I linked to above in post 3. :sunglasses:


(www.rboyapps.com - Make your home your butler!) #10

So why ZigBee? With most devices now supporting Z-Wave plus I’m trying to understand why would someone prefer a zigbee device?


(Ray) #11

The biggest supporters for zigbee I would think = price and selections.


#12

Several reasons.

  1. Hops. Z wave, including zwave plus, is limited to a maximum of four hops, while zigbee home automation (which is the profile that smartthings uses) can do 15 into the hub and another 15 out. So if you need to get around architectural barriers in a particular building, or you’re trying to get across the yard into an outbuilding, you may have a lot more options with Zigbee.
  1. zigbee power utilization is still a little bit better even than zwave plus, giving you somewhat longer battery life. From a consumer point of view this is most obvious in somewhat higher sensitivity or shorter reporting times for battery operated devices, because you don’t have to worry about running the battery down quite as quickly. Many community members in these forums, for example, report that they get the best responsiveness from the zigbee motion sensors.

  2. maximum devices. Z wave has a hard stop at 232 devices, including the hub. Zigbee can handle many more. This is one of the main reasons why most smartbulbs use zigbee rather than Zwave.

  3. network efficiency. This is getting down into very technical issues, but zigbee is just a little more efficient. You can see that even with just a network heal. Many manufacturers suggest a practical limit not of 232 Z wave devices on the network, but something closer to 150, just because you can’t get the Z wave repair to ever finish otherwise. zigbee handles neighbor tables differently and more efficiently so again, it can just handle a lot more devices.

  4. transmission efficiency. zigbee is somewhat better transmitting through rain or snow or humidity than Z wave, which is why so many devices designed for outdoor deployment use zigbee.

That’s not to say that zwave doesn’t have its own strengths. It does. In particular, the fact that WiFi can interfere with zigbee but doesn’t with zwave is a big deal, particularly for a fixed location devices like door locks and light switches. Especially if they’re being deployed by a DIY person who doesn’t have any network mapping tools available.

So different devices will work for different use cases, and people will have different preferences, but there are definitely reasons why someone might use zigbee for a particular deployment. :sunglasses:


(www.rboyapps.com - Make your home your butler!) #13

Great info JD.

So from a practical point of view for 90%+ of the users z-wave is a better bet for the most important reason that it wont interfere with the Wifi network. That alone may lead to a more stable environment.

Now the time zigbee would be helpful is when you have more than 200 devices around the house or you have a very large complex farm or setup over large distances requiring multiple hops. For most houses under 7-8k sq ft should IMHO fall within the 4 hop range.
Battery life I’ll take your word for it because my ecolink sensors are still at 90%+ after 2 years and I use them a couple of times a day. I think the device consuming the battery is a bigger issue than the protocol communication consumption of the battery in most cases. For e.g. Locks and thermostats would run down the battery because of the internal electronics faster than the communication with the hub. So the zigbee would be helpful in ultra low power devices likes a sensor which doesn’t consume any overhead beyond the protocol communication. Thats where zigbee may shine, assuming again that wifi doesn’t interfere otherwise it may end up re transmitting which will lose the competitive advantage.
I see your point about the bulbs since you would have more than 200 bulbs. But honestly I can’t imagine having 200 bulbs in my house and I have 20+ rooms. In fact for powered devices the battery won’t be a concern. I’m just having a hard time trying to see when all the benefits of zigbee would overcome the wifi disadvantage.

This isn’t to discredit any of the information you provided which is solid and accurate, just from a practical point I think that the wifi issue overrides all the other advantages.


(www.rboyapps.com - Make your home your butler!) #14

Now that’s a solid reason. It’s like BluRay vs HDDVD. Interesting to see how this plays out.


#15

Zigbee won’t generally interfere with Wi-Fi because it really is a very low power protocol. But boosted wifi can drown out zigbee.

As far as battery power and sensitivity… I think this comes up most often when people want to use a motion sensor to trigger lights coming on indoors, such as in a hallway or just walking into a room. And the under $25 range, you can choose either the iris zigbee sensor or the Phillips hue zigbee sensor, and either is likely to be noticeably quicker than an inexpensive Z wave sensor like GoControl or ecolink. This is the use case where the difference between 1.5 seconds and 2.5 seconds is likely to feel like an eternity. :sunglasses::bulb:

If you go to the more expensive zwave sensors like the aeotec or Fibaro, you can pick up some sensitivity again. But you either have to put them on USB power, such as with the aeotec, or change batteries more often than the zigbee.


(www.rboyapps.com - Make your home your butler!) #16

I had benchmarked some of the popular z wave motion sensors some time ago here:

I wonder if anyone has something similar for ZigBee vs ZWave sensors?


#17

I don’t know if he kept numbers, but @johnconstantelo has done some comparisons.


#18

Since that post that @JDRoberts referenced, the only zwave devices I have left are about 75 GE switches, and about 20 battery powered zwave sensors. I’ve replaced almost every zwave sensor with zigbee sensors that’s possible, including my First Alert zcombo smoke/co detectors with Halo devices.

I don’t have supporting numbers for what I did except personal experience. I can have a zwave motion sensor sitting right next to a zigbee (Lowe’s or ST’s), and every single time the zigbee sensor beats the zwave one in terms of reporting status to ST, which in turn causes smartapps to be that mush snappier.

Since I also have Alexa speaking events, I can first unlock a door (re-purposed Ecolink sensor) and then open it (Iris on the door), and I’ll get the open notification before I get the unlock notification a lot of the times.

I even replaced my Ecolink mailbox sensor with an original SmartSense Multi, and it works great without the need for a zigbee repeater outside the house (I have an Iris smartplug on a wall in the garage).


(Wayne) #19

I have a bunch of fibaro motion sensors and they are always slower than the st motions and the xiaomi ones. I do not know how much of this is down to implementation of hardware including the pir and other electronics, rather than due to z-wave versus zigbee, but as @johnconstantelo states it does make everything feel snappier. I therefore much prefer the zigbee devices in areas of high and frequent traffic for switching lights as the fibaros allow you to walk much further in darkness before the lights come on even set at highest sensitivity.