wifi question

On 19/12/14 11:39, Roger wrote:
On 19/12/2014 03:38, Bill Wright wrote:
I put this on uk tv broadcast but then thought there'll be more people
on here who would know about wifi, so here it is on here as well.

I have wifi analyser app on my phone, and I also have a wi-spy thingy.
Why are almost all wifis on channels 1, 6, or 11? I can see that they
are form the only combination of three channels that don't overlap at
all, but I would have thought that better results would be obtained in
many cases by using the other channels, especially the ones midway
between the over-occupied ones. I was at a friend's house last night and
she was complaining that her wifi didn't work too well. This was an old
house with thick walls. The modem was in the dining room and in the
kitchen next door the signal was very poor, but usable I would have
thought. But in most locations in the room the signal on the same
channel (11) from the house across the road (by chance the kitchen
window faces across the road to the living room of the opposite cottage,
where their modem is). This is a village high street, with quite dense
housing. Behind my friend's property and about 40m from her house is a
new estate. Stepping outside and walking a few yards I found seven other
wifis, all on channel 11. So I wrote down the occupancy on each channel,
as found by walking along the pavement on both sides for 10 paces up the
road and ten paces down the road, and also from standing at one point at
the bottom the garden near the new houses. The results (ch then number
of wifis) we

1: 5
2: 0
3: 0
4: 1
5: 0
6: 8
7: 0
8: 1
9: 0
10:0
11: 8
12: 0.

This from memory. The one given as ch4 might have been 5.

Subsequently I put the wi-spy on the dashboard and drove around. The
channel usage generally is much the same as reported above. It's quite
rare to see a wifi on any channel other than 1, 6, and 11.

Now this seems a bit barmy to me. Why don't wifi installers find a clear
channel, or at least a channel without complete overlap? Do wifis come
preset with channels 1, 6, and 11? Can't they be altered?

Bill
It's because channels 1, 6 and 11 are the only ones that dont overlap
each other. Any of the channels in between overlap 1, 6 or 11 (whichevr
2 they are inbetween) as well as each other. This is more complicated
hese days as high speed routers can use 2 channels but the basic
principle is the same - if you use channel 6 you wont overlap with
someone on channel 1 or 11. Have a look at the diag in the wiki article
http://en.wikipedia.org/wiki/List_of_WLAN_channels


It's more like: they are the default channels most manufacturers select
as they don't overlap, are in the US group and most users don't change
channels.

I use 13 in preference, but my wifi capable printer is limited to US
channels!!!

--
PeeGee

"Nothing should be able to load itself onto a computer without the
knowledge or consent of the computer user. Software should also be able
to be removed from a computer easily."
Peter Cullen, Microsoft Chief Privacy Strategist (Computing 18 Aug 05)

On 19/12/14 12:08, Martin wrote:
On Fri, 19 Dec 2014 10:56:23 +0000, Indy Jess John
wrote:

On 19/12/2014 03:38, Bill Wright wrote:

Now this seems a bit barmy to me. Why don't wifi installers find a clear
channel, or at least a channel without complete overlap? Do wifis come
preset with channels 1, 6, and 11? Can't they be altered?

My Toshiba laptop can list all the wifi signals it can see along with
SSID and signal strength.

From SSID names it looks as though Sky normally defaults to 1 and
Virginmedia defaults to 11. The layman's advice on the internet
suggests that if the default doesn't work, try channel 6.

The ones that seem to be channel agile appear to only seek on power on
and then stay with it, and if somebody else uses the same one nearby
afterwards they get interference later. So they ring the help line and
the advice given first of all is to switch off and back on, and of
course that fixes it because the seek finds a better channel.

Personally, having looked at the set I can see from my house, I have
chosen channel 9 and if that suddenly gets an overlap, I should use
Channel 4. I leave mine on all the time so no channel agile one is going
to swamp me.

Really? I have mine on all the time too. There are often more than a dozen wifi
modems/routers going at the same time near me. Eventually if I do nothing others
will use the same frequency as me.


My neighbour seems to have auto enabled - within a minute or two of me
changing channel, his switches to the same one. It is the only signal
better than -80dB (apart from mine, of course).

--
PeeGee

"Nothing should be able to load itself onto a computer without the
knowledge or consent of the computer user. Software should also be able
to be removed from a computer easily."
Peter Cullen, Microsoft Chief Privacy Strategist (Computing 18 Aug 05)

On Fri, 19 Dec 2014 03:38:27 +0000, Bill Wright wrote:

I have wifi analyser app on my phone, and I also have a wi-spy thingy.
Why are almost all wifis on channels 1, 6, or 11?

Here's a screenshot from inSSIDer showing a similar situation in my
neighbourhood, although there is one channel 2 user and one on 3 (me).

https://drive.google.com/file/d/0B3z...ew?usp=sharing

--

TOJ.

On 19/12/2014 13:23, Bill Wright wrote:
Roger wrote:

It's because channels 1, 6 and 11 are the only ones that dont overlap
each other. Any of the channels in between overlap 1, 6 or 11
(whichevr 2 they are inbetween) as well as each other.

It appears to me (could be wrong) the the energy distribution is
greatest on the nominal channel, and falls off towards the edges of the
group of channels actually used. In that case it would be better to use
intermediate channels, even though there would be some overlap.

The real answer is to move to the 5Ghz Wi-Fi band. This may mean buying
a new router and Wi-Fi dongle but is well worth it in my experience if
you are in an urban area.


--
Peter Crosland

Reply address is valid

On 19/12/2014 12:08, Martin wrote:

Really? I have mine on all the time too. There are often more than a dozen wifi
modems/routers going at the same time near me. Eventually if I do nothing others
will use the same frequency as me.



At 11:13pm I'm detecting 32 nearby wi-fi identities. The congested
bands are 1, 6 and 11.

I have my router configured to band 4 which I'm sharing with only a
couple of other wi-fi users. Band 9 is also relatively clear.

--
mailto: news {at} admac {dot] myzen {dot} co {dot} uk

alan_m wrote:

I'm detecting 32 nearby wi-fi identities. The congested
bands are 1, 6 and 11.

I have my router configured to band 4 which I'm sharing with only a
couple of other wi-fi users.

Even if nobody else near you is using ch4, you will partly overlap with
everyone using ch2,3, 5 and 6.

On 19/12/2014 03:38, Bill Wright wrote:
I put this on uk tv broadcast but then thought there'll be more people
on here who would know about wifi, so here it is on here as well.

I have wifi analyser app on my phone, and I also have a wi-spy thingy.
Why are almost all wifis on channels 1, 6, or 11? I can see that they
are form the only combination of three channels that don't overlap at
all, but I would have thought that better results would be obtained in
many cases by using the other channels, especially the ones midway
between the over-occupied ones. I was at a friend's house last night and
she was complaining that her wifi didn't work too well. This was an old
house with thick walls. The modem was in the dining room and in the
kitchen next door the signal was very poor, but usable I would have
thought. But in most locations in the room the signal on the same
channel (11) from the house across the road (by chance the kitchen
window faces across the road to the living room of the opposite cottage,
where their modem is). This is a village high street, with quite dense
housing. Behind my friend's property and about 40m from her house is a
new estate. Stepping outside and walking a few yards I found seven other
wifis, all on channel 11. So I wrote down the occupancy on each channel,
as found by walking along the pavement on both sides for 10 paces up the
road and ten paces down the road, and also from standing at one point at
the bottom the garden near the new houses. The results (ch then number
of wifis) we

1: 5
2: 0
3: 0
4: 1
5: 0
6: 8
7: 0
8: 1
9: 0
10:0
11: 8
12: 0.

This from memory. The one given as ch4 might have been 5.

Subsequently I put the wi-spy on the dashboard and drove around. The
channel usage generally is much the same as reported above. It's quite
rare to see a wifi on any channel other than 1, 6, and 11.

Now this seems a bit barmy to me. Why don't wifi installers find a clear
channel, or at least a channel without complete overlap? Do wifis come
preset with channels 1, 6, and 11? Can't they be altered?

Bill

Surely this is well known. If you just randomly overlap with interfering
WiFI there is no possibility of co-operation at all while if you stay on
the same channel as the interference then the networks can co-operate to
some extent to avoid lost packets.

--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.

On 19/12/2014 15:15, Martin wrote:

I cam only reveive/monitor wifi on the original frequency. What do you see if
you monitor the newer frequency? Is that heading towards saturation too?


ISTM that 5GHz WiFI is pretty empty in suburban areas, but moderately
crowded in towns and cities.

--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.

On 19/12/2014 23:46, Andy Burns wrote:
alan_m wrote:

I'm detecting 32 nearby wi-fi identities. The congested
bands are 1, 6 and 11.

I have my router configured to band 4 which I'm sharing with only a
couple of other wi-fi users.

Even if nobody else near you is using ch4, you will partly overlap with
everyone using ch2,3, 5 and 6.


Yes - meaning more than twice the chance of your packets being corrupted.

--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.

On 19/12/2014 19:25, Peter Crosland wrote:
On 19/12/2014 13:23, Bill Wright wrote:
Roger wrote:

It's because channels 1, 6 and 11 are the only ones that dont overlap
each other. Any of the channels in between overlap 1, 6 or 11
(whichevr 2 they are inbetween) as well as each other.

It appears to me (could be wrong) the the energy distribution is
greatest on the nominal channel, and falls off towards the edges of the
group of channels actually used. In that case it would be better to use
intermediate channels, even though there would be some overlap.

The real answer is to move to the 5Ghz Wi-Fi band. This may mean buying
a new router and Wi-Fi dongle but is well worth it in my experience if
you are in an urban area.



5GHz seems to have much less ability to go through walls though.

--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.