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Channel usage

wireshock
Tutor

Channel usage

Hi all,

 

I am considering buying an Orbi kit, but I am seriously concerned that both the router and satellite use the same frequency channels for client connections.  This makes no sense to me.  I know the issue has been raised before, but I hope someone knowledgeable (from NETGEAR, perhaps) can explain the reason for this.  I really doubt that the router and satellite somehow cooperate on the same freqyency; more likely they act as two individual access points and interfere with each other.  (And different clients connected to them also jam each other.)  So, how does this really work?  Are there plans to enable different channel selection for them in a future firmware release?

Model: Orbi High-Performance AC3000 Tri-Band WiFi System (RBK50)
Message 1 of 8

Re: Channel usage

there is no issue with using the same channels on both router and sat as long as the coverage overlap is not to great , the clients will not have an issue when roaming

Message 2 of 8
Narkhelek
Aspirant

Re: Channel usage

Here's the full answer:  Due to how 802.11 works a router and a single satellites will not interfer with each other.  It's part of the spec that wifi devices on the same channel coordinate their transmissions. Since the APs need to be close enough to each other to have reliable communications for the backhaul to work they are close enough to coordinate.  However, it does nothing to benefit performance since only one AP in the pair can talk at a time to their respective clients.  Where this can become a problem is when you have multiple satellites and the satellites are far enough away from each other (for example on opposite sides of the router) that they cannot coordinate their transmissions.  Then you can have problems with two or more satellites transmitting at the same time causing interferrence with the router or clients who are inbetween.  Additionally you could have issues with clients who are too far away to coordinate with APs or clients other than the one they are associated with which can cause interferrence with other clients or APs.

 

Basically, using the same channels at best will cause a loss in performance, which is the reason why there is a separate backhaul channel to begin with.  At worse sharing channels will cause interferrence leading to packet loss.  On 2.4Ghz they might as well share channels since it's so crowded anyways but on 5Ghz there is no reason or valid excuse to doing so.

Message 3 of 8
Narkhelek
Aspirant

Re: Channel usage

I'd just like to add that despite this odd design choice my Orbi has been providing awesome performance for myself and everyone else who's reviewed it.  So I guess the proof is in the pudding in this case.

Message 4 of 8
wireshock
Tutor

Re: Channel usage


@peteytesting wrote:

there is no issue with using the same channels on both router and sat as long as the coverage overlap is not to great , the clients will not have an issue when roaming


Well, one issue with this system could be that the less there is overlap, the weaker the backhaul connection will be.  This is further complicated by the fact that there are two frequency bands to consider, with different signal propagation properties.

Message 5 of 8
wireshock
Tutor

Re: Channel usage

I've been looking through the user manual and I don't see an option to select the 20MHz or 40MHz mode in either the 2.4GHz or 5GHz band.  Netgear routers usually let you do this by selecting the speed along with the channel, like 130 or 300 for 802.11n.  The only related option I see is to enable or disable 20/40 coexistence.  What does this mean?  Does Orbi just default to "fat channels", unless prevented by the coexistence mechanism?  I'd really like to have more control over this.

Message 6 of 8
DarrenM
NETGEAR Moderator

Re: Channel usage

Hello wireshock

 

Orbi had band steering and makes that decision on its own to put devices on best possible channel so no way to manually control this.

 

DarrenM

Message 7 of 8
wireshock
Tutor

Re: Channel usage


@DarrenM wrote:

Hello wireshock

 

Orbi had band steering and makes that decision on its own to put devices on best possible channel so no way to manually control this.

 

DarrenM


Hi DarrenM,

 

Band steering is unrelated to what I was talking about.

 

I understand that the reason to have the router and satellites operate on the same channel (in either band) is probably to make it easier for clients to roam.  This design reduces the total system capacity and leads to potential interference problems, but maybe it does alllow better roaming.  OK.

 

But, why does Orbi not have the option to select the 20MHz or 40MHz mode in either band?  All the other Netgear routers have this option.  Orbi defaults to 40MHz in the 2.4GHz band, unless prevented by 20/40 coexistence, and it always does 80MHz in the 5Ghz band!

Message 8 of 8
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