I have a main router and the other computers have wifi in my home. In the
far bedroom I get only spotty reception as a couple walls appear to block
the reception. Is there either a better antenna to put on the main router
or a repeater I can buy to put in between the router and the far bedroom
wifi to enhance range? Any info appreciated.
You can use either an antenna or repeater.
I chose to use a repeater, just make sure what ever you use, it will work
with your router.
Check on your manufacturer's website for a list of products that will work
with your specific router.
If you wish further assistance, please advise what router you are using
including the model number.
Gene
http://www.ejmconsulting.org
"snow" <sandyscamper@yahoo.com> wrote in message
news:ZVYSg.3852$Dq3.1135@trndny06...
> I have a main router and the other computers have wifi in my home. In the
> far bedroom I get only spotty reception as a couple walls appear to block
> the reception. Is there either a better antenna to put on the main router
> or a repeater I can buy to put in between the router and the far bedroom
> wifi to enhance range? Any info appreciated.
>
>
>I have a main router and the other computers have wifi in my home. In the
>far bedroom I get only spotty reception as a couple walls appear to block
>the reception. Is there either a better antenna to put on the main router
>or a repeater I can buy to put in between the router and the far bedroom
>wifi to enhance range? Any info appreciated.
Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
> "snow" <sandyscamper@yahoo.com> hath wroth:
> >I have a main router and the other computers have wifi in my home. In the
> >far bedroom I get only spotty reception as a couple walls appear to block
> I have a main router and the other computers have wifi in my home. In the
> far bedroom I get only spotty reception as a couple walls appear to block
> the reception. Is there either a better antenna to put on the main router
> or a repeater I can buy to put in between the router and the far bedroom
> wifi to enhance range? Any info appreciated.
If it's the walls, neither antenna reflector nor repeater will help much
unless you can place the repeater so that the dogleg line of sight goes
around the walls. Your best shot is to run a cable past the walls to
connect an access point to your router.
> If it's the walls, neither antenna reflector nor repeater will help much
> unless you can place the repeater so that the dogleg line of sight goes
> around the walls. Your best shot is to run a cable past the walls to
> connect an access point to your router.
The key is that it already works. The signal is getting there. A
reflector will help. The signal needn't bore through the wall, either.
My best line of WiFi from my living room is down the hall, not directly
through a couple of outside walls in line with the router. If I'm
outdoors using a cantenna on the laptop, the best signal is not directly
from the router, but through a nearby window.
VNC or Remote Desktop, running between a PC at the router and a PC at the
desired location, can be used to monitor the signal strength while
adjustments are made in router positioning and reflector orientation.
The router should probably be up high.
--
---
Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5
> Axel Hammerschmidt <hlexa@hotmail.com> wrote:
>
>> If it's the walls, neither antenna reflector nor repeater will help
>> much unless you can place the repeater so that the dogleg line of
>> sight goes around the walls. Your best shot is to run a cable past
>> the walls to connect an access point to your router.
>
> The key is that it already works. The signal is getting there. A
> reflector will help.
Reflectors are for longish distance and clear line of sight. The presence
of some weak signal could be because of spurious reflections.
> The signal needn't bore through the wall, either.
> My best line of WiFi from my living room is down the hall, not
> directly through a couple of outside walls in line with the router.
> If I'm outdoors using a cantenna on the laptop, the best signal is not
> directly from the router, but through a nearby window.
Better for OP to lower fregmentation and RTS/CTS.
> VNC or Remote Desktop, running between a PC at the router and a PC at
> the desired location, can be used to monitor the signal strength while
> adjustments are made in router positioning and reflector orientation.
Wireless is for portables and that means you have to deal with changing
locations.
Axel Hammerschmidt <hlexa@hotmail.com> hath wroth:
>dold@XReXXhowXt.usenet.us.com wrote in alt.internet.wireless:
>> The signal needn't bore through the wall, either.
>> My best line of WiFi from my living room is down the hall, not
>> directly through a couple of outside walls in line with the router.
>> If I'm outdoors using a cantenna on the laptop, the best signal is not
>> directly from the router, but through a nearby window.
>Better for OP to lower fregmentation and RTS/CTS.
I beg to differ.
Packet fragmentation is only useful for dealing with interference. The
idea is that smaller packets will have a higher probablity of arriving
than larger packets. The OP's original complaint was lack of signal
(i.e. dead spots) for which smaller packets will do nothing.
CTS/RTS is only useful for dealing with "hidden nodes" otherwise known
as collisions with client radios that can't hear each other. My
guess(tm) is that the threshold for using CTS/RTS flow control is
about 10 clients. Setting the actual threshold (minimum packet size
to fragment) is somewhat tricky as you need to know the average packet
size being used. This varies by type of traffic. Flow control
tweaking isn't going to do anything for lack of signal.
Just to be complete, there's also a problem with setting the speed
control. That's in the access point and is usually set to "auto".
When the access point starts seeing interfernce, collisions, and weak
signals, it slows down in order to improve the receive sensitivity and
thereby improve the BER (bit error rate). However, if it's
interference that's causing the problem, it will have interference at
any speed, and end up at the very slowest speed of 1Mbit/sec. Dumb,
methinks.
The problem is that 100% packet delivery at 1Mbit/sec is much slower
than perhaps a 30% probability of delivery at perhaps 12Mbits/sec.
I've been fixing the system speed for one of the slowest OFDM speeds
(6, 9, or 12Mbits/sec) depending in internet connection speed, and
getting much better results than leaving it at auto. This tweak also
isn't going to do much for lack of signal.
So, what does one do for dead spots? In order starting with my
favorite:
1. Bigger or better antennas.
2. Additional access point with CAT5 wire backhaul to main router.
3. Better technology (MIMO).
4. Powerline, phone line, or CATV bridging.
5. WDS bridge.
6. Repeater.
7. Bi-directional amplifier.
8. Dead Spot Remover:
| http://www.doityourself.com/stry/blood
Out damn spot, out I say...
snow wrote:
> I have a main router and the other computers have wifi in my home. In the
> far bedroom I get only spotty reception as a couple walls appear to block
> the reception. Is there either a better antenna to put on the main router
> or a repeater I can buy to put in between the router and the far bedroom
> wifi to enhance range? Any info appreciated.
>
>
Hi,
Placing router in a better spot is not an option?
Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
> Axel Hammerschmidt <hlexa@hotmail.com> hath wroth:
>
> >dold@XReXXhowXt.usenet.us.com wrote in alt.internet.wireless:
> >
> >> The signal needn't bore through the wall, either.
> >> My best line of WiFi from my living room is down the hall, not
> >> directly through a couple of outside walls in line with the router.
> >> If I'm outdoors using a cantenna on the laptop, the best signal is not
> >> directly from the router, but through a nearby window.
>
> >Better for OP to lower fregmentation and RTS/CTS.
>
> I beg to differ.
>
> Packet fragmentation is only useful for dealing with interference. The
> idea is that smaller packets will have a higher probablity of arriving
> than larger packets. The OP's original complaint was lack of signal
> (i.e. dead spots) for which smaller packets will do nothing.
Low signal to noise is also interference. Anyway, we do not know
anything about the OP's environment. And it's worth trying fragmentation
(and RTS/CTS) before the OP starts to annoy any neighbours with a
stronger signal.
Yep. If you have interference, it will show up as low signal to noise
ratio. Nothing in the original posting that even hints at an
interference problem.
>Anyway, we do not know
>anything about the OP's environment.
True. But we know that he's trying to fix a "dead spot" which is not
quite the right description. He's looking for a fix for:
"In the far bedroom I get only spotty reception as a couple
walls appear to block the reception."
So, how is twiddling with settings going to improve signal strength?
>And it's worth trying fragmentation
>(and RTS/CTS) before the OP starts to annoy any neighbours with a
>stronger signal.
As I stated. RTS/CTS flow control is only useful for collision
control, specifically with hidden nodes. Need references? However, I
agree. It's worth the effort twiddling with every last lousy setting
and control just to see what it does and doesn't do. Part of Learn By
Destroying(tm).
Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
> hlexa@hotmail.com (Axel Hammerschmidt) hath wroth:
>
> >Low signal to noise is also interference.
>
> Yep. If you have interference, it will show up as low signal to noise
> ratio. Nothing in the original posting that even hints at an
> interference problem.
Interference can very well be the cause of spotty reception.
> >Anyway, we do not know
> >anything about the OP's environment.
>
> True. But we know that he's trying to fix a "dead spot" which is not
> quite the right description. He's looking for a fix for:
> "In the far bedroom I get only spotty reception as a couple
> walls appear to block the reception."
> So, how is twiddling with settings going to improve signal strength?
Because improving signal strength does not necessarily eliminate "spotty
reception". Targeting a stronger signal against a reflecting wall does
not improve the signal on the other side of the wall.
> >And it's worth trying fragmentation
> >(and RTS/CTS) before the OP starts to annoy any neighbours with a
> >stronger signal.
>
> As I stated. RTS/CTS flow control is only useful for collision
> control, specifically with hidden nodes.
RST/CTS flow control is useful in dealing with many types of
interference. In practice, fragmentation threshold and RTS/CTS are often
combined.
"The goal of carrier sense is to detect when transmissions or
interferences are happening on the channel, to withold of our own
transmissions until a better time (we also avoid corrupting other people
transmissions). Carrier sense uses the measure of energy strength at the
antenna."
[...]
"Most systems also perform virtual carrier sense through the use of
RTS/CTS [4], which improves carrier sense information, eliminates hidden
node effects and reduces the penalty of collision (shorter collisions)."
Note *interferences* in "The goal of carrier sense is to detect when
transmissions or interferences are happening on the channel..." and that
RTS/CTS "improves carrier sense information,...".
And before you point that out, yes RTS/CTS is very efficient when
dealing with CSMA interferers and less efficient with non-CSMA
interferences. But that doesn't justify your conclusion, that RTS/CTS is
"only useful for collision control" with hidden nodes.
> However, I agree. It's worth the effort twiddling with every last lousy
> setting and control just to see what it does and doesn't do. Part of
> Learn By Destroying(tm).
>Interference can very well be the cause of spotty reception.
Yep. The problem is that interference is usually quite variable. It
comes and goes. There are very few sources of CONTINUOUS
interference. See list at: http://wireless.wikia.com/wiki/Wi-Fi#Interference
Even the municipal networks have their quiet times. The only one that
I know that shows up continuously is the wireless security camera or
wireless X10 video extension. I would expect the OP to mention such
equipment if it were a potential problem. However, if it really is an
interference problem, I'm surprised that you didn't mention some of
the standard methods of interference identification and mitigation.
For example, changing channels, moving the client away from windows,
using Netstumbler or Kismet, spectrum analyzers, etc.
Reading the original question of:
"In the far bedroom I get only spotty reception as a couple
walls appear to block the reception."
It would appear that the OP has already determined the cause of the
"spotty reception". A few walls blocking the signal are simpler and
more obvious problem than interference.
>Because improving signal strength does not necessarily eliminate "spotty
>reception". Targeting a stronger signal against a reflecting wall does
>not improve the signal on the other side of the wall.
True. Reflections are always a problem. 802.11g does a fairly
decent job of dealing with reflections as compared to 802.11b and
802.11. MIMO, beam steering, and beam forming do an even better job.
Reading a bit between the lines, it would appear that the entire
bedroom is a dead spot, which would imply that it's not a reflections
issue. If you've ever had to deal with a reflections issue, you
probably would have noticed that the effect varies enormously with
location and position. Move a few cubits one way or other and the
signal could easily be stable and usable. My guess(tm) is that the OP
would have tried a few possible positions before asking for help. It's
probably not reflections.
>RST/CTS flow control is useful in dealing with many types of
>interference. In practice, fragmentation threshold and RTS/CTS are often
>combined.
Yep. In practice, improving antenna location, directivity, and gain
are more commonly used to deal with interference issues. We've
diverted substantially from the original question. I'll reply on the
CTS/RTS flow control and fragmentation issues a bit later. Remind me
if I forget. Lunch first.
Incidentally, the paper was from 1998 and deals exclusively with early
analog 802.11 chipsets. I think (not sure) that modern all digital
802.11g chipsets don't use carrier detection for interference
detection but only use data validity detection or preamble S/N
measurement. If the data arrives corrupted, it's assume that
something else interfered with the transmission. RSSI detection is
just too slow and subject to blocking and overload. I gotta do some
digging and reading to be sure.
On Thu, 28 Sep 2006 23:30:01 GMT, "snow" <sandyscamper@yahoo.com>
wrote:
>I have a main router and the other computers have wifi in my home. In the
>far bedroom I get only spotty reception as a couple walls appear to block
>the reception. Is there either a better antenna to put on the main router
>or a repeater I can buy to put in between the router and the far bedroom
>wifi to enhance range? Any info appreciated.
>
I've been fighting this same kind of problem between my upstairs
office desktop computer and my wife's downstairs kitchen
computer. The aluminum faced wallboard is likely the thing that
is blocking the signal.
I'm considering having a garage sale to get rid of my wireless
equipment, then replace it with a household wiring LAN setup. I'd
be very interested in hearing from those who have done this. How
well did it work?
Gordon <gordonlr@deleteswbell.net> wrote:
> I've been fighting this same kind of problem between my upstairs
> office desktop computer and my wife's downstairs kitchen
> computer. The aluminum faced wallboard is likely the thing that
> is blocking the signal.
Aluminum faced wallboard? That would be annoying.
If it works at all, though, you can improve things with directional
antennas. If the downstairs PC is in a fixed location, it can get an
antenna as well.
Remember that the stock antennas have a radiation pattern shaped like a
donut. You probably want the antennas broadside to each other, maybe like
a parallelogram. Except if you are trying to go through a floor, a bounce
to a stairwell might be better... hard to say.
I have used the "Hawking HAI6SDA Directional 6dBi 2.4GHz Antenna" with good
success on a Netgear WG311 PCI card. $20-30.
<http://www.hawkingtech.com/products/productlist.php?CatID=32&FamID=58&ProdID=122>
It fit the Netgear, and had an adapter that fit RP-TNC.
And the Windsurfer reflector on the router.
--
---
Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5
>Gordon <gordonlr@deleteswbell.net> wrote:
>> I've been fighting this same kind of problem between my upstairs
>> office desktop computer and my wife's downstairs kitchen
>> computer. The aluminum faced wallboard is likely the thing that
>> is blocking the signal.
>
>Aluminum faced wallboard? That would be annoying.
>If it works at all, though, you can improve things with directional
>antennas. If the downstairs PC is in a fixed location, it can get an
>antenna as well.
>
>Remember that the stock antennas have a radiation pattern shaped like a
>donut. You probably want the antennas broadside to each other, maybe like
>a parallelogram. Except if you are trying to go through a floor, a bounce
>to a stairwell might be better... hard to say.
>
>I have used the "Hawking HAI6SDA Directional 6dBi 2.4GHz Antenna" with good
>success on a Netgear WG311 PCI card. $20-30.
><http://www.hawkingtech.com/products/productlist.php?CatID=32&FamID=58&ProdID=122>
>It fit the Netgear, and had an adapter that fit RP-TNC.
>
>And the Windsurfer reflector on the router.
>
I've tinkered around with antenna positioning and location just
about all I can. The setup works, but the downstairs computer
signal is very weak, and if something bumps the antenna or gets
in the line of sight the signal may fail.
I would like to change over to an LAN system that uses the house
wiring instead of a Wi-Fi setup, but I have never talked with
anyone who has used such a setup.
Gordon wrote:
> I would like to change over to an LAN system that uses the house
> wiring instead of a Wi-Fi setup, but I have never talked with
> anyone who has used such a setup.
>
> Gordon
That's cuz you never asked... I have 6 of the Powerline Networking things
(they come in pairs)... Netgear has 14Mb for $99, 54Mb for $129, 85Mb for
$149, and they announced a 200Mb one a few months ago, but I don't have one
(needs a gigabit ethernet on the computer).. I not only use them for
directly connecting computers to a network, but I was plaing around and put
two of my WAP/Routers on them, and have a huge wifi area, and can share
stuff wired too...
>
> I'm considering having a garage sale to get rid of my wireless
> equipment, then replace it with a household wiring LAN setup. I'd
> be very interested in hearing from those who have done this. How
> well did it work?
It will work really well. Consider that most networks are wired for that
reason and wireless is a fairly recent not as good but convenient
choice. For non-portable computers my first choice is always wired.
snow wrote:
> I have a main router and the other computers have wifi in my home. In the
> far bedroom I get only spotty reception as a couple walls appear to block
> the reception. Is there either a better antenna to put on the main router
> or a repeater I can buy to put in between the router and the far bedroom
> wifi to enhance range? Any info appreciated.
Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
> hlexa@hotmail.com (Axel Hammerschmidt) hath wroth:
>
> >Interference can very well be the cause of spotty reception.
>
> Yep. The problem is that interference is usually quite variable. It
> comes and goes. There are very few sources of CONTINUOUS
> interference. See list at:
> http://wireless.wikia.com/wiki/Wi-Fi#Interference
Nothing about spotty reception in the Wiki :-(
<snip>
> Reading the original question of:
> "In the far bedroom I get only spotty reception as a couple
> walls appear to block the reception."
> It would appear that the OP has already determined the cause of the
> "spotty reception". A few walls blocking the signal are simpler and
> more obvious problem than interference.
Good.
> >Because improving signal strength does not necessarily eliminate "spotty
> >reception". Targeting a stronger signal against a reflecting wall does
> >not improve the signal on the other side of the wall.
>
> True.
Installing a reflector on the wireless router was your suggestion
<snip>
> Reading a bit between the lines, it would appear that the entire
> bedroom is a dead spot, which would imply that it's not a reflections
> issue. If you've ever had to deal with a reflections issue, you
> probably would have noticed that the effect varies enormously with
> location and position. Move a few cubits one way or other and the
> signal could easily be stable and usable. My guess(tm) is that the OP
> would have tried a few possible positions before asking for help. It's
> probably not reflections.
Spotty reception in the bedroom, which an entire dead spot, and the OP's
already moved the walls around...?
The facts are, you don't know.
> >RST/CTS flow control is useful in dealing with many types of
> >interference. In practice, fragmentation threshold and RTS/CTS are often
> >combined.
>
> Yep. In practice, improving antenna location, directivity, and gain
> are more commonly used to deal with interference issues.
But flow control is much easier, and should it fix the spotty reception
in the bedroom, the PO will have saved himself the trouble.
And the walls...
<snip>
> Incidentally, the paper was from 1998 and deals exclusively with early
> analog 802.11 chipsets. I think (not sure) that modern all digital
> 802.11g chipsets don't use carrier detection for interference
> detection but only use data validity detection or preamble S/N
> measurement. If the data arrives corrupted, it's assume that
> something else interfered with the transmission. RSSI detection is
> just too slow and subject to blocking and overload. I gotta do some
> digging and reading to be sure.
Well, the author does note, that RTS/CTS is [...] less efficient with
non-CSMA interferences, implying that it can be used to improve spotty
reception, when caused by interference.
>Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
>> Yep. The problem is that interference is usually quite variable. It
>> comes and goes. There are very few sources of CONTINUOUS
>> interference. See list at:
>> http://wireless.wikia.com/wiki/Wi-Fi#Interference
>Nothing about spotty reception in the Wiki :-(
True. The Wiki/FAQ is built on user contributions. Contributions and
corrections are always welcome. There are plenty of topics that have
not been mentioned or are incomplete.
The issue I raised is about the characteristics of different types of
interference that could possibly cause the OP's "dead spot" or "spotty
reception". I suggested that this would imply continuous
interference. Since interference is *YOUR* theory, and allegedly
responsible for possibly causing the OP's problems, could I trouble
you to suggest what manner of device could possibly cause continuous
interference? Also, some remedial measures as I find it odd that you
would suggest tweaking timing parameters rather than identifying the
cause and either eliminating or avoiding it.
>Installing a reflector on the wireless router was your suggestion
Correct. "spotty reception" implies that there is some reception in
the bedroom. An increase in signal strength should improve the
situation. If the house is long and narrow, redirecting some of the
RF in the direction of the bedroom will be a big help. If the
wireless router is at one end of the house, and the bedroom at the
other, this would be ideal for an antenna reflector arrangement.
>> Reading a bit between the lines, it would appear that the entire
>> bedroom is a dead spot, which would imply that it's not a reflections
>> issue. If you've ever had to deal with a reflections issue, you
>> probably would have noticed that the effect varies enormously with
>> location and position. Move a few cubits one way or other and the
>> signal could easily be stable and usable. My guess(tm) is that the OP
>> would have tried a few possible positions before asking for help. It's
>> probably not reflections.
>
>Spotty reception in the bedroom, which an entire dead spot, and the OP's
>already moved the walls around...?
Sorry. I wasn't specific enough for you. I'm suggesting that the OP
move the wireless device (laptop or desktop) to various locations in
the bedroom to avoid any possible null and reflection problems. I
don't think that moving walls will be cost effective.
>The facts are, you don't know.
True. But it's so much fun to speculate or guess(tm).
Usually, the OP supplies additional detail at this point, but he's
apparently given up and considering power line networking. That will
work and is easier if he can find a common power line segment.
So, what does one do for dead spots? In order starting with my
favorite:
1. Bigger or better antennas.
2. Additional access point with CAT5 wire backhaul to main router.
3. Better technology (MIMO).
4. Powerline, phone line, or CATV bridging.
5. WDS bridge.
6. Repeater.
7. Bi-directional amplifier.
8. Dead Spot Remover: http://www.doityourself.com/stry/blood
Out damn spot, out I say...
>But flow control is much easier, and should it fix the spotty reception
>in the bedroom, the PO will have saved himself the trouble.
As I previously mentioned... I advocate playing with every single last
lousy setting in the router just to see what happens. Who knows, one
might find something interesting, useful, or entertaining. One might
also learn something. In every router that I have owned, I make it a
point of understanding and testing all the settings. No big deal on a
commodity router, but a major challenge with a WRT54G and DD-WRT
firmware. It's all part of Learn By Destroying(tm). In the case of
the current "dead spot" problem, I predict that adding flow control
will not do anything useful.
>And the walls...
Use a shofar. ...and the walls came tumbling down.
>> Incidentally, the paper was from 1998 and deals exclusively with early
>> analog 802.11 chipsets. I think (not sure) that modern all digital
>> 802.11g chipsets don't use carrier detection for interference
>> detection but only use data validity detection or preamble S/N
>> measurement. If the data arrives corrupted, it's assume that
>> something else interfered with the transmission. RSSI detection is
>> just too slow and subject to blocking and overload. I gotta do some
>> digging and reading to be sure.
>Well, the author does note, that RTS/CTS is [...] less efficient with
>non-CSMA interferences, implying that it can be used to improve spotty
>reception, when caused by interference.
I don't see where you get that implication, but I can guess(tm).
Usually, interference reduction is measured using the signal to noise
ratio. That was fairly straight forward with analog receivers. The
signal strength versus the remaining noise level between packets.
However, with the introduction of all digital receivers, there was a
change to measuring the SNR using the error rate. 100% reception
success, with no corrupted or trashed packets, was deemed perfect SNR.
If corrupted packets were decoded, the SNR value was reduced. The
correlation is marginal with the previous analog methods but good
enough for site surveys and antenna aiming.
In this SNR case, you are correct. Increasing the probability of a
packet arriving without corruption, by reducing its size (i.e.
fragmentation), or preventing transmission when the channel is "noisy"
(RTS/CTS flow), would improve the SNR. The only problem is that both
will slow down the thruput considerably.
Incidentally, CTS/RTS is the common term for modem flow control.
RTS/CTS is the common term for wireless. I guess I'll have to change
over to using RTS/CTS. Sigh.
>
> That's cuz you never asked... I have 6 of the Powerline Networking things
> (they come in pairs)... Netgear has 14Mb for $99, 54Mb for $129, 85Mb for
> $149, and they announced a 200Mb one a few months ago, but I don't have one
> (needs a gigabit ethernet on the computer).. I not only use them for
> directly connecting computers to a network, but I was plaing around and put
> two of my WAP/Routers on them, and have a huge wifi area, and can share
> stuff wired too...
>
> Got the netgear ones at Best Buy, but here's the link to the netgear site
> (if you can't get them locally, you can order them online)
> http://www.netgear.com/Products/Brid...Extenders.aspx
>
>
>
Do you have any experience using them at a fairly long distance such as
between 2 buildings where one is powered from the other?
I was over a friends the other night and they have a real hodgepodge of
wireless repeaters that perform poorly. I think putting one AP at the
other end of the house and another AP in his little "office" that is
attached to the garage which is around 250' away from the house and
using one XE102 attached to the main router and a WGX102 at each distant
location.
I remember trying the original powerline stuff a few years ago and it
maxed out at 150'.
Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
> hlexa@hotmail.com (Axel Hammerschmidt) hath wroth:
>
> > Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> wrote:
> >
> >> Yep. The problem is that interference is usually quite variable. It
> >> comes and goes. There are very few sources of CONTINUOUS
> >> interference. See list at:
> >> http://wireless.wikia.com/wiki/Wi-Fi#Interference
>
> > Nothing about spotty reception in the Wiki :-(
<snip>
> The issue I raised is about the characteristics of different types of
> interference that could possibly cause the OP's "dead spot" or "spotty
> reception". I suggested that this would imply continuous
> interference. Since interference is *YOUR* theory, and allegedly
> responsible for possibly causing the OP's problems, could I trouble
> you to suggest what manner of device could possibly cause continuous
> interference?
Spotty just means irregular. It doesn't have to be in physical "spots".
> Also, some remedial measures as I find it odd that you
> would suggest tweaking timing parameters rather than identifying the
> cause and either eliminating or avoiding it.
Se later on...
> > Installing a reflector on the wireless router was your suggestion
>
> Correct. "spotty reception" implies that there is some reception in
> the bedroom. An increase in signal strength should improve the
> situation. If the house is long and narrow, redirecting some of the
> RF in the direction of the bedroom will be a big help. If the
> wireless router is at one end of the house, and the bedroom at the
> other, this would be ideal for an antenna reflector arrangement.
Might only give more reflections. Like pissing (or farting) windwards.
> >> Reading a bit between the lines, it would appear that the entire
> >> bedroom is a dead spot, which would imply that it's not a reflections
> >> issue. If you've ever had to deal with a reflections issue, you
> >> probably would have noticed that the effect varies enormously with
> >> location and position. Move a few cubits one way or other and the
> >> signal could easily be stable and usable. My guess(tm) is that the OP
> >> would have tried a few possible positions before asking for help. It's
> >> probably not reflections.
> >
> > Spotty reception in the bedroom, which an entire dead spot, and the OP's
> > already moved the walls around...?
>
> Sorry. I wasn't specific enough for you. I'm suggesting that the OP
> move the wireless device (laptop or desktop) to various locations in
> the bedroom to avoid any possible null and reflection problems. I
> don't think that moving walls will be cost effective.
>
> > The facts are, you don't know.
>
> True. But it's so much fun to speculate or guess(tm).
>
> Usually, the OP supplies additional detail at this point, but he's
> apparently given up and considering power line networking. That will
> work and is easier if he can find a common power line segment.
Yes. Getting closer to the cause is difficult in that situation.
> So, what does one do for dead spots? In order starting with my
> favorite:
> 1. Bigger or better antennas.
But think of the neighbours. And remember CB Radio.
> 2. Additional access point with CAT5 wire backhaul to main router.
Good solution! But remember also to turn down the power.
> 3. Better technology (MIMO).
Not so good, in this case. Reflections!
> 4. Powerline, phone line, or CATV bridging.
Powerline never works, or so I've heard.
<snip>
> >But flow control is much easier, and should it fix the spotty reception
> >in the bedroom, the PO will have saved himself the trouble.
>
> As I previously mentioned... I advocate playing with every single last
> lousy setting in the router just to see what happens. Who knows, one
> might find something interesting, useful, or entertaining. One might
> also learn something. In every router that I have owned, I make it a
> point of understanding and testing all the settings. No big deal on a
> commodity router, but a major challenge with a WRT54G and DD-WRT
> firmware. It's all part of Learn By Destroying(tm). In the case of
> the current "dead spot" problem, I predict that adding flow control
> will not do anything useful.
Depends, amongst other things, on what's causing the interfence.
Fortunately, the one access point I have managed to destroyed was under
warranty
> >And the walls...
>
> Use a shofar. ...and the walls came tumbling down.
>
> >> Incidentally, the paper was from 1998 and deals exclusively with early
> >> analog 802.11 chipsets. I think (not sure) that modern all digital
> >> 802.11g chipsets don't use carrier detection for interference
> >> detection but only use data validity detection or preamble S/N
> >> measurement. If the data arrives corrupted, it's assume that
> >> something else interfered with the transmission. RSSI detection is
> >> just too slow and subject to blocking and overload. I gotta do some
> >> digging and reading to be sure.
>
> >Well, the author does note, that RTS/CTS is [...] less efficient with
> >non-CSMA interferences, implying that it can be used to improve spotty
> >reception, when caused by interference.
>
> I don't see where you get that implication, but I can guess(tm).
> Usually, interference reduction is measured using the signal to noise
> ratio.
We don't know anything about the signal to noise ratio. The implication
in the link is, that flow control "improves carrier sense information".
> That was fairly straight forward with analog receivers. The
> signal strength versus the remaining noise level between packets.
> However, with the introduction of all digital receivers, there was a
> change to measuring the SNR using the error rate. 100% reception
> success, with no corrupted or trashed packets, was deemed perfect SNR.
> If corrupted packets were decoded, the SNR value was reduced. The
> correlation is marginal with the previous analog methods but good
> enough for site surveys and antenna aiming.
George wrote:
> Peter Pan wrote:
>
>>
>> That's cuz you never asked... I have 6 of the Powerline Networking
>> things (they come in pairs)... Netgear has 14Mb for $99, 54Mb for
>> $129, 85Mb for $149, and they announced a 200Mb one a few months
>> ago, but I don't have one (needs a gigabit ethernet on the
>> computer).. I not only use them for directly connecting computers to
>> a network, but I was plaing around and put two of my WAP/Routers on
>> them, and have a huge wifi area, and can share stuff wired too...
>>
>> Got the netgear ones at Best Buy, but here's the link to the netgear
>> site (if you can't get them locally, you can order them online)
>> http://www.netgear.com/Products/Brid...Extenders.aspx
>>
>>
>>
>
> Do you have any experience using them at a fairly long distance such
> as between 2 buildings where one is powered from the other?
>
> I was over a friends the other night and they have a real hodgepodge
> of wireless repeaters that perform poorly. I think putting one AP at
> the other end of the house and another AP in his little "office" that
> is attached to the garage which is around 250' away from the house and
> using one XE102 attached to the main router and a WGX102 at each
> distant location.
>
>
> I remember trying the original powerline stuff a few years ago and it
> maxed out at 150'.
As a matter of fact yes... Before I sold the place and came to Baltimore, I
had a 5 acre place in Northern Idaho, so far out in the sticks no cable/dsl
(39 miles NE of spokane wa), so had a sat system for the house, and power
from the house to both the garage (about 500 feet away), and the back guest
house (about 1/4 mile away).. Used the powerline networking to send the
stuff from the sat to the "out-buildings".. That was fine when for wired
inside stuff, but I had several notebooks and a PDA all with wifi... So I
used Linksys WRT45G (actually mean it to be plural, but afraid readers would
think i meant GS rather than G's) in each location to give me wired or
wireless access (same ssid/diff channel, but all made one HUGE hot area)..
If it was nice I could go outside wireless, when cold and snowy I could stay
inside and use either wired or wireless...
As an aside, I tried wireless at first, but after the first snowstorm (the
wireless didn't work when it snowed heavy, course neither did the sat), I
had metal snowroofs on stilts put over the tops of the buildings, and that
blocked the wireless altogether.. I had a ditch dug for power/utils to the
garage (and guest area), so since it had power from the main in from the
house, tried the powerline stuff.. Interestingly enuf it not only worked
great, but when the power failed and the gen kicked in, it still worked fine
to the out-buildings...
As another aside, my friend down the street, used it in a metal
hulled/bulkhead diesel ship used during the summer for the inland passage to
alaska.. Wireless wouldn't go thru the metal bulkheads, but all rooms had
power off the generator, so it was an easy way to network different areas..
As for the wap/routers, don't know (i used linksys, the G models ((NOT the
gs)) were $49 each at walmart), but can't imagine why the WGX's wouldn't
work also, just have no personal experience with that model....
>Spotty just means irregular. It doesn't have to be in physical "spots".
The neighbors dog is named Spot. The kids call him Spotty. Judging
by the mess he leaves behind my wood pile, he's not very regular.
>We don't know anything about the signal to noise ratio. The implication
>in the link is, that flow control "improves carrier sense information".
>
>> That was fairly straight forward with analog receivers. The
>> signal strength versus the remaining noise level between packets.
>> However, with the introduction of all digital receivers, there was a
>> change to measuring the SNR using the error rate. 100% reception
>> success, with no corrupted or trashed packets, was deemed perfect SNR.
>> If corrupted packets were decoded, the SNR value was reduced. The
>> correlation is marginal with the previous analog methods but good
>> enough for site surveys and antenna aiming.
>Hmm! Not sure how this relates to carrier sense?
No problem...
In order to detect interference, the receiver needs to know what
constitutes interference and at what threshold to block transmission.
It makes no sense to have any and all detected RF be declared as
interference as BPSK and OFDM can extract data from rather low signal
to noise ratios. For example, 54Mbits/sec requires a 17dB minimum
SNR. I vaguely recall that it's about 6dB at 1Mbit/sec (not sure).
The device at one end of a link sends the receive SNR to the other end
to allow the sender to determine if it should be allowed to transmit.
Incidentally, much of the noise is contributed by internal digital
noise from other parts of the router or client radio, which is also
responsible for some of the weird variations in receiver sensitivity.
An ideal interference detection circuit would measure the receive SNR.
If it's over 17dB SNR for 54Mbits/sec, there is sufficient margin to
decode the data and transmissions are allowed. If the resultant SNR
is less than 17dB, then transmission is blocked under the assumption
that the interference will prevent reception. So far so good.
The problem is how to measure SNR. In the older analog devices, the
SNR was simply the peak RSSI during transmission divided by the
detected noise level between transmissions. This is adequate but
slow. As 802.11g speeds and short preambles made it more difficult to
use analog techniques, all digital methods were employed. The current
method is to use the detected data error rate as a measure of SNR. If
some packets arrived corrupted, it would be assumed to have been
perpetrated by "noise". The more corrupted packets, the more noise,
and the smaller the SNR per some conversion scheme. The effect is the
same. When the interference is sufficient to seriously interfere,
then transmission is blocked.
The term "carrier sense" is an analog term, that really only applies
to analog chipsets. The last of these were the Prism I chipsets with
it's mixers and analog front ends. Todays chips are all digital and
direct conversion (no mixers).
If one implements flow control (RTS/CTS) in such a system, the SNR
will improve simply because the system now has an additional method of
detecting interference and measuring SNR. Instead of relying on just
the SNR of the other end of the link to determine when to transmit,
the system now adds flow control handshake management packets that
determine when *BOTH* ends of the link have sufficient SNR to xmit.
This does very well for eliminating "hidden nodes" but also improves
the all digital version of SNR by simply improving the chances that a
packet will arrive intact.
As always, there's no free lunch. If you use flow control to improve
delivery reliability, the overhead will slow down the thruput. I
don't know the exact performance hit, but my testing showed that it's
substantial. It's as I hinted in a previous rant, 100% delivery at
1Mbit/sec is considerably slower than an error prone 30% delivery at
perhaps 12Mbits/sec. That same thing with flow control. If you
improve the delivery probability by blocking xmission during
interference, the system will by necessity slow down.
Jeff Liebermann <jeffl@comix.santa-cruz.ca.us> hath wroth:
>In order to detect interference, the receiver needs to know what
>constitutes interference and at what threshold to block transmission.
>It makes no sense to have any and all detected RF be declared as
>interference as BPSK and OFDM can extract data from rather low signal
>to noise ratios. For example, 54Mbits/sec requires a 17dB minimum
>SNR. I vaguely recall that it's about 6dB at 1Mbit/sec (not sure).
"snow" <sandyscamper@yahoo.com> wrote in message
news:ZVYSg.3852$Dq3.1135@trndny06...
>I have a main router and the other computers have wifi in my home. In the
>far bedroom I get only spotty reception as a couple walls appear to block
>the reception. Is there either a better antenna to put on the main router
>or a repeater I can buy to put in between the router and the far bedroom
>wifi to enhance range? Any info appreciated.
>
Snow:
I read most of the responses. I did not see one that mentioned the simplest
solution. Try moving your AP a bit. If that doesn't work, change the
orientation of the antenna. Vertical to horizontal, or horizontal to
vertical. Sometimes small changes and alteration in orientation fixes
things. Then you can go to the reflectors, (note, do that and you will
create a new dead spot behind the reflector).
how to expand router in dead spot of house? 
Linear Mode
