Manual selection of channels in Smart Hub (Home Hub 6)

[bratman91]

If I try to manually change the channels in my Smart Hub, the only options seem to be three or four channels that the “Smart” facility presumably thinks are best. How can I turn of the smart feature to allow me to choose the channels? 

[bratman91]

Answering my own post, I see from a thread five years ago that the Smart Hub will not allow the full range of channels to be selected but offers only three. The wifi diagnostic tool of my iMac tells me that there are a number of wifi networks in the immediate area, many of which are BT ones, and they nearly all use the same three channels that the Smart Hub does. It is difficult to avoid interference if the Smart Hub will allow only the channels that are most “popular” to be selected - it’s not a very smart Smart Hub!

[WSH]

And a good thing too.  What people do not appreciate is that the channels are not completely separate.  Most overlap with the channels either side causing “adjacent interference”.  You will see that in the 5GHz range the channels have been set four apart, 36, 40, 44 etc. because of this.  With 2.4GHz there was an oversight in in the design allowing channels 1, 2, 3, 4 etc.  In fact, only channels 1, 6 and 11 are far enough apart do not overlap and cause “adjacent interference”.  For once BT have been intelligent by limiting the settings to only these three.

Don’t worry about sharing a channel with others.  This is far less problematic that using the channels in between.  There is a mechanism called CSMA/CA, (Carrier Sensing, Multiple Access/Collision Avoidance), that allows the wireless units to cooperate.  The others will respond to an RTS, (request to send), signal and go quiet while you send etc.  This mechanism can only work if the channels can hear each other clearly.  Channels that partly overlap, like 1 and 3 can hear each other’s noise but cannot hear each other clearly enough to cooperate.  This just makes things worse for everyone around.  Stick to channels 1, 6 and 11.

[licquorice]

@WSH  They are only non-overlapping if everybody sticks to 1,6 and 11

I don't know the answer, but interested to know how CSMA/CA operates when a channel is saturated with someone streaming.

[WSH]

My point exactly!  Presumably why BT have chosen to block people using the other channels in the latest hubs.

The original CSMA/CA wouldn’t work, which I think was the reason for the RTS/CTS extension to the original design.  Even streaming is not continuous from the WAPs point of view though, (hence the reason the client runs it through a buffer).  It has to be broken down into frames, so presumably the RTS get a chance to interrupt it between frames.  Interesting point though.  Personally, I share the view of the rest of the industry…you only use wireless when you have to.  Well worth the effort of putting cables in.

[bratman91]

@WSH 

I don’t think that I agree with you that this is a good thing. My garden office (where my iMac is located) is on a line between my router and a block of buildings where a number of signals on the “popular” channels emanate from. The office is a fair distance from my router and somewhat closer to the block of buildings.

Thus, the iMac can see lots of strong signals on, say, channel 1 from the building but only a weaker channel 1 signal from my router. At my router, the signals from the block of buildings are not detected. I don’t see how RTS can work in this case. Perhaps selecting a channel between 1, 6 and 11 would not give any improvement but it would never hurt to try, but the “BT knows best” approach prevents this and simply antagonises customers.