Speed lost in repeater mode

Hello,

I'm using 2 DLink DWL 900 AP+ wifi access points : one as an access
point, connected to a
DSL modem, another as a repeater for the first one.

If they are close (10 meters (30 ft) no obstacle) to eachother
everything works fine.

The problem is that if the distance between the 2 AP's increases and if
there are obstacles, the bitrate collapses down to at most 120 kbps,
and sometimes 46 kbps.
This is a pitty since i am trying to share a 512kbps DSL connection.

If my wireless PC is directly connected to the AP, without using the
repeater, the bitrate is quite good (500kbps when downloading from the
internet)

Where does the problem come from ?
Is it due to the repeater configuration ?

I have already added a high gain antenna to the repeater, hoping it
will increase the signal strength between AP and repeater and so the
birate will increase too, but it didn't really change anything...

Thanks in advance for any help.

--
Nicolas.

"SLO" <(E-Mail Removed)> hath wroth:

>I'm using 2 DLink DWL 900 AP+ wifi access points : one as an access
>point, connected to a
>DSL modem, another as a repeater for the first one.

Which hardware version DWL900AP+ ? I'll guess C1.

>If they are close (10 meters (30 ft) no obstacle) to eachother
>everything works fine.
>
>The problem is that if the distance between the 2 AP's increases and if
>there are obstacles,

Increases how far? What distance? What obstacles? Numbers please.

Are you using the stock antennas or something better? If not look
into adding reflectors to boost the signal:
http://www.freeantennas.com

>the bitrate collapses down to at most 120 kbps,
>and sometimes 46 kbps.

That's really slow. It could be due to interference or weak signal.
Is this indoors (going through several walls) or outdoors (susceptible
to interference)?

Also note that your speed through a repeater will be half (or less) of
the speed going direct.

>This is a pitty since i am trying to share a 512kbps DSL connection.
>
>If my wireless PC is directly connected to the AP, without using the
>repeater, the bitrate is quite good (500kbps when downloading from the
>internet)

Repeaters suck. Compatibility and timing problems like this are all
too common.

>Where does the problem come from ?
>Is it due to the repeater configuration ?

No, it's probably a timing problem in the repeater. The DWL900AP+ has
a short list of "compatible" products.
| http://support.dlink.com/faq/view.as...WL-900AP+_revC
It take 3 boxes to play repeater. I know that two are DWL-900AP+
boxes. What's the third box?

>I have already added a high gain antenna to the repeater, hoping it
>will increase the signal strength between AP and repeater and so the
>birate will increase too, but it didn't really change anything...

Some things to try:

1. Verify you have the latest firmware:
| http://support.dlink.com/products/vi...00AP%2B%5FrevC

2. Disarm the 4x mode. See:
| http://support.dlink.com/emulators/d...v_perform.html

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Thanks for your answer.

Jeff Liebermann wrote:
..
>
> Which hardware version DWL900AP+ ? I'll guess C1.

rev C2 for both DWL 900AP+

> Increases how far? What distance? What obstacles? Numbers please.
The AP is located at the second floor of a French coutry style house,
under the roof (made of tiles).
So the only obstacle is the roof since the repeater uses an external
outdoor antenna.
The distance between the AP and the repeater's outdoor antenna is 10
meters (30 feet).

I have first made tests placing the AP and repeater at 6 meters (20
feet) from eachother and without any obstacle (direct view). In these
conditions everything worked fine.


> Are you using the stock antennas or something better? If not look
> into adding reflectors to boost the signal:

The AP uses his omnidirectionnal stock antenna and as I have already
written, the repeater uses an outdoor high gain (15 dB) helicoïdal
antenna coupled to an omnidirectional indoor antenna to distribute
signal inside a second building.
The repeater is connected to those to antennas using an antenna
coupler.

>
> That's really slow. It could be due to interference or weak signal.
> Is this indoors (going through several walls) or outdoors (susceptible
> to interference)?
This is half indoor and outdoor as described.
I have already been thinking to use an outdoor directionnal antenna for
the first AP, but it would be difficult to install this antenna on
the first building an to install the wire to feed it. In fact it would
be as difficult as installing an ethernet cable between the 2
buildings...

> No, it's probably a timing problem in the repeater. The DWL900AP+ has
> a short list of "compatible" products.
> | http://support.dlink.com/faq/view.as...WL-900AP+_revC
> It take 3 boxes to play repeater. I know that two are DWL-900AP+
> boxes. What's the third box?

In the first building there is a DSL modem.
To share the DSL internet connection, a DLink DI 524 wifi router is
connected to the DSL modem through ethernet.
Since the DI 524 is not compatible to the DWL 900 AP+ in repeater mode,
i have connected a DWL 900AP+ to the DI 524's ethernet switch and
configured it as an Access Point.
In a second building, where i want to distribute the internet
connection, is located the second DWL 900AP+ configured as a repeater
for the DWL 900AP+ Access Point.
And finally i use my laptop Acer computer with built in wifi to connect
to the repeater.

> 1. Verify you have the latest firmware:
> | http://support.dlink.com/products/vi...00AP%2B%5FrevC

I 'm using the last firmware.

> 2. Disarm the 4x mode. See:
> | http://support.dlink.com/emulators/d...v_perform.html

Already done.

"SLO" <(E-Mail Removed)> hath wroth:

>> Which hardware version DWL900AP+ ? I'll guess C1.
>rev C2 for both DWL 900AP+

Well, I was close. The A1 and B1 versions do not have the repeater
feature.

>> Increases how far? What distance? What obstacles? Numbers please.
>The AP is located at the second floor of a French coutry style house,
>under the roof (made of tiles).
>So the only obstacle is the roof since the repeater uses an external
>outdoor antenna.
>The distance between the AP and the repeater's outdoor antenna is 10
>meters (30 feet).

Roof tiles are a substantial obstacle. 2.4GHz will go through roof
tiles but not without some loss. Unfortuantely, I don't have any
numbers for the attenuation.

>I have first made tests placing the AP and repeater at 6 meters (20
>feet) from eachother and without any obstacle (direct view). In these
>conditions everything worked fine.

OK. That means that the radios and such are working.

>> Are you using the stock antennas or something better? If not look
>> into adding reflectors to boost the signal:

>The AP uses his omnidirectionnal stock antenna and as I have already
>written, the repeater uses an outdoor high gain (15 dB) helicoïdal
>antenna coupled to an omnidirectional indoor antenna to distribute
>signal inside a second building.
>The repeater is connected to those to antennas using an antenna
>coupler.

Antenna coupler? Is that a power splitter or power combiner? I'm not
sure, but it appears that you have two transmitters connected to the
same antenna. That's a rather bad idea. When one transmitter goes on
the air, the other receiver is sure to be overloaded and desensitized.
The power splitter will offer perhaps 20-30dB of isolation, but that's
not enough to prevent overload. Even if the radios are on different
channels, there will still be some receiver overload (i.e. blocking).
There's also the possibility of the transmitters mixing and produceing
intermodulation products. You won't hear these, but other services
will see the interference. Is this what you're doing or am I reading
your description incorrectly?

>> That's really slow. It could be due to interference or weak signal.
>> Is this indoors (going through several walls) or outdoors (susceptible
>> to interference)?

>This is half indoor and outdoor as described.

Well, if it is interference, it should come and go with time of day.
Very few sources of wireless intereference are on the air 24 hours per
day. If it's a problem all the time, it's probably NOT interference.

>I have already been thinking to use an outdoor directionnal antenna for
>the first AP, but it would be difficult to install this antenna on
>the first building an to install the wire to feed it. In fact it would
>be as difficult as installing an ethernet cable between the 2
>buildings...

Well, given the choice, running wire (or fiber) is always better than
wireless. If the outdoor antenna can position the line of sight over
the obstructing tile roof, the problem will probably be solved.

>In the first building there is a DSL modem.
>To share the DSL internet connection, a DLink DI 524 wifi router is
>connected to the DSL modem through ethernet.
>Since the DI 524 is not compatible to the DWL 900 AP+ in repeater mode,
>i have connected a DWL 900AP+ to the DI 524's ethernet switch and
>configured it as an Access Point.

Is the DWL900AP+ on the same RF channel (1, 6, or 11) as the DI-524?
It should NOT be.

Looks like the DI-524 radio section isn't really necessary for testing
the repeater link. Try turning OFF the wireless part of the DI-524
and see if the DWL900AP+ performance improves.

>In a second building, where i want to distribute the internet
>connection, is located the second DWL 900AP+ configured as a repeater
>for the DWL 900AP+ Access Point.
>And finally i use my laptop Acer computer with built in wifi to connect
>to the repeater.

Except for my comments on the sharing of an antenna, this seems to be
a workable system. The DWL900AP+ should certainly be compatible with
another DWL900AP+. That leaves the attenuation caused by the tile
roof. I don't know of any way to eliminate the loss, other than
repositioning the antennas for line of sight.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Thanks again for your answer.

> Antenna coupler? Is that a power splitter or power combiner? I'm not
> sure, but it appears that you have two transmitters connected to the

My home-made antenna coupler is intended to connect 2 antennas on the
same repeater.
It's a kind of "splitter". I have one cable connected to the repeater
antenna socket onone side and to the "coupler" (or splitter) on the
other side. And the coupler is connected to my outdoor helicoidal
antenna on one side, and to an indoor omnidirectionnal antenna on the
otherside. The antenna coupler is a kind of "T".
Here is a link where you kind see what it looks like :
http://f5jtz.club.fr/pjacquet/coupl.htm

If i didn't use this coupler and only the outdoor antenna, my repeater
would receive signal from AP but my laptop computer wouldn't be able to
receive repeater signal. And if i only used the omnidirectionnal
antenna on the repeater, my laptop computer would receive signal from
repeater but the repeater wouldn't be able to connect to AP.
So I had to use one directionnal outdoor antenna to connect the
repeater to the AP, and also an indoor omnidirectional antenna to
connect the repeater to my laptop computer.
Since I had to use 2 antennas, I had to use an antenna coupler (or
signal splitter).

> Well, if it is interference, it should come and go with time of day.
> Very few sources of wireless intereference are on the air 24 hours per
> day. If it's a problem all the time, it's probably NOT interference.
>

The bitrate loss occurs 24 hours per day.


>
> Well, given the choice, running wire (or fiber) is always better than
> wireless. If the outdoor antenna can position the line of sight over
> the obstructing tile roof, the problem will probably be solved.
>
I think that's what i am going to try next.
Maybe i could first use an indoor directionnal antenna connected to AP
and oriented in direction of repeater through roof.
If the problem is still present I could put this antenna outdoor.


> Is the DWL900AP+ on the same RF channel (1, 6, or 11) as the DI-524?
> It should NOT be.

DI-524 is on channel 6 and the two DWL900AP+ are on channel 10.

> Looks like the DI-524 radio section isn't really necessary for testing
> the repeater link. Try turning OFF the wireless part of the DI-524
> and see if the DWL900AP+ performance improves.
>

> Except for my comments on the sharing of an antenna, this seems to be
> a workable system. The DWL900AP+ should certainly be compatible with
> another DWL900AP+. That leaves the attenuation caused by the tile
> roof. I don't know of any way to eliminate the loss, other than
> repositioning the antennas for line of sight.

What I don't understand is that my repeater seems to be more sensitive
to signal attenuation, or obstacles than any laptop computer or wifi
adapter.
Indeed if i stand with my laptop computer outdoor and connect directly
to AP the bitrate is very good. But if i use my DWL 900AP+ in the same
location, as a repeater, or even as a wireless client connected to my
laptop through an ethernet cable, bitrate collapses...

Thanks again for your answer.

> Antenna coupler? Is that a power splitter or power combiner? I'm not
> sure, but it appears that you have two transmitters connected to the

My home-made antenna coupler is intended to connect 2 antennas on the
same repeater.
It's a kind of "splitter". I have one cable connected to the repeater
antenna socket onone side and to the "coupler" (or splitter) on the
other side. And the coupler is connected to my outdoor helicoidal
antenna on one side, and to an indoor omnidirectionnal antenna on the
otherside. The antenna coupler is a kind of "T".
Here is a link where you kind see what it looks like :
http://f5jtz.club.fr/pjacquet/coupl.htm

If i didn't use this coupler and only the outdoor antenna, my repeater
would receive signal from AP but my laptop computer wouldn't be able to
receive repeater signal. And if i only used the omnidirectionnal
antenna on the repeater, my laptop computer would receive signal from
repeater but the repeater wouldn't be able to connect to AP.
So I had to use one directionnal outdoor antenna to connect the
repeater to the AP, and also an indoor omnidirectional antenna to
connect the repeater to my laptop computer.
Since I had to use 2 antennas, I had to use an antenna coupler (or
signal splitter).

> Well, if it is interference, it should come and go with time of day.
> Very few sources of wireless intereference are on the air 24 hours per
> day. If it's a problem all the time, it's probably NOT interference.
>

The bitrate loss occurs 24 hours per day.


>
> Well, given the choice, running wire (or fiber) is always better than
> wireless. If the outdoor antenna can position the line of sight over
> the obstructing tile roof, the problem will probably be solved.
>
I think that's what i am going to try next.
Maybe i could first use an indoor directionnal antenna connected to AP
and oriented in direction of repeater through roof.
If the problem is still present I could put this antenna outdoor.


> Is the DWL900AP+ on the same RF channel (1, 6, or 11) as the DI-524?
> It should NOT be.

DI-524 is on channel 6 and the two DWL900AP+ are on channel 10.

> Looks like the DI-524 radio section isn't really necessary for testing
> the repeater link. Try turning OFF the wireless part of the DI-524
> and see if the DWL900AP+ performance improves.
>

> Except for my comments on the sharing of an antenna, this seems to be
> a workable system. The DWL900AP+ should certainly be compatible with
> another DWL900AP+. That leaves the attenuation caused by the tile
> roof. I don't know of any way to eliminate the loss, other than
> repositioning the antennas for line of sight.

What I don't understand is that my repeater seems to be more sensitive
to signal attenuation, or obstacles than any laptop computer or wifi
adapter.
Indeed if i stand with my laptop computer outdoor and connect directly
to AP the bitrate is very good. But if i use my DWL 900AP+ in the same
location, as a repeater, or even as a wireless client connected to my
laptop through an ethernet cable, bitrate collapses...

On 27 Jun 2006 18:17:54 -0700, "SLO" <(E-Mail Removed)> wrote:

>Thanks again for your answer.
>
>> Antenna coupler? Is that a power splitter or power combiner? I'm not
>> sure, but it appears that you have two transmitters connected to the
>
>My home-made antenna coupler is intended to connect 2 antennas on the
>same repeater.
>It's a kind of "splitter". I have one cable connected to the repeater
>antenna socket onone side and to the "coupler" (or splitter) on the
>other side. And the coupler is connected to my outdoor helicoidal
>antenna on one side, and to an indoor omnidirectionnal antenna on the
>otherside. The antenna coupler is a kind of "T".
>Here is a link where you kind see what it looks like :
>http://f5jtz.club.fr/pjacquet/coupl.htm

That will work (with 35 ohm line) sorta. It has almost no isolation
between ports. The more complex Wilkinson divider/splitter/combiner,
has about 20-30dB of isolation between ports.
| http://www.microwaves101.com/encyclo...rs.cfm#twoport
For sharing two antennas on a single, the isolation requirement is
minimal. All you need to do is make sure that the antennas do NOT see
each other. If they do, you will have nulls and peaks, with the
accompanying weird antenna patterns.

For sharing 2 antennas, you can probably get away with using just a
T-connector, and a 35 ohm coax cable that's an odd multiple of 1/4
wavelengths from the xmitter to the t-connector junction. You only
need the splitter if you have a high power xmitter, where the VSWR
might cause it to shut down, or blow up.

>If i didn't use this coupler and only the outdoor antenna, my repeater
>would receive signal from AP but my laptop computer wouldn't be able to
>receive repeater signal. And if i only used the omnidirectionnal
>antenna on the repeater, my laptop computer would receive signal from
>repeater but the repeater wouldn't be able to connect to AP.

Oh, I see. Well, that's a good reason to use one.

>The bitrate loss occurs 24 hours per day.

Then, it's probably not interference. There are a few RF sources that
are on the air continuously. See if any of these are possible:
http://wireless.wikia.com/wiki/Wi-Fi#Interference
My best guess is that the attenuation of the roof tiles is the
problem.

>> Is the DWL900AP+ on the same RF channel (1, 6, or 11) as the DI-524?
>> It should NOT be.
>
>DI-524 is on channel 6 and the two DWL900AP+ are on channel 10.

Well, there is a slight bit of overlap between 6 and 10. Try 6 and 11
or better yet, try 1 and 11.

>What I don't understand is that my repeater seems to be more sensitive
>to signal attenuation, or obstacles than any laptop computer or wifi
>adapter.

Well, if the DWL900AP+ had some form of signal level meter, it would
be easy to determine the relative effects. However, without numbers,
we're just doing guesswork. If you have an attenuator, you might try
locating the radios close together and putting the attenuation in
series with the antenna lead. Then you can tell how much attenuation
the system can handle, which should give you an idea of what range to
expect.

>Indeed if i stand with my laptop computer outdoor and connect directly
>to AP the bitrate is very good. But if i use my DWL 900AP+ in the same
>location, as a repeater, or even as a wireless client connected to my
>laptop through an ethernet cable, bitrate collapses...

Your laptop apparently just has a better receiver than the DWL900AP+.
Most 802.11g radios are generally better quality designs than 802.11b
only radios, such as the DWL900AP+.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS