Re: How to boost our Linksys WRT150N's signal -- across the house?



On Sun, 28 Dec 2008 15:51:07 -0800, dgates <dgates@xxxxxxxxxxxxxx>
wrote:

I may have overstated the "thick walls." The primary thick wall is
the one (well, two) separating the add-on office from the rest of the
house.

Never mind the over or under statements. How many walls? What are
the walls made from? Any aluminium foil backed insulation in the
walls?

Rule of thumb: 1 wall is usually no problem. 2 walls are a problem
but can be made to work if sufficiently thin. 3 walls will get you an
unstable and unreliable connection. If there is any foil insulation
in the walls, forget it. Also, RF likes to travel in straight lines,
so count the number of walls along the RF path, not through doorways,
hallways, closets, etc.

East (office):
"94% (excellent)" from a TiVo.

Middle (family & dining room):
"64% (good)" from a TiVo
"2 out of 5 bars" from a laptop

2 out of 5 is not my idea of good. Lacking real numbers, I would
guess 3 out of 5 bars would be a minimum.

West (living room):
"2 out of 5 bars" from a laptop

Same as above. Barely tolerable. As I previously mentioned, you can
make it work with this signal level, but I don't think you'll enjoy
having it drop out every time something moves or changes along the
path.

South (exercise room):
"41% (marginal)" from a TiVo

Yep. Still functional but I would hate to measure the speed and
reliability.


Maybe I misunderstood how a booster would work. I assume that it's
analogous to one guy yelling to another guy. If you boost the volume
of the yelling guy's voice, you don't need to also boost the other
guy's hearing. No?

Close. Place two guys far enough apart so that they can just barely
hear each other. Now, place a 3rd guy in the middle to play repeater.
He listens for one of the other end guy to yell something. When he
hears something with a destination address of the other guy, he saves
the message, turns around, and yells it to the other guy. The reply
goes the same way. The middle guy just stores and plays back the
message.

Now, what's important here is that the end guys can just barely hear
each other. If both the end guys are yelling at the same time, the
middle guy will be confused. If the middle guy is replaying a message
and the originating guy decides to send yet another message, the other
end guy hears both at the same time and gets it muddled. Lots of
other combinations that won't work.

The answer is that only one of the 3 guys can do their yelling at a
time. The means that the repeater monopolizes about twice the air
time as a single transmission directly from end to end. That's where
the bandwidth gets cut in half. Also note that to have it cut exactly
in half, the 3 guys have to have perfect timing. That's rarely the
case and collisions are common. The result is that a repeater
typically reduces maximum thruput by more than half. Also note that
it works best if the end points cannot hear each other.

One solution is to use two radios as a repeater. The link between one
guy and the repeater is one channel. The link between the repeater
and the other guy is on a different channel. With two radios in the
repeater, they can transmit and receive simultaneously, thus
eliminating the 50% max performance hit.

You won't find these at consumer prices, but you can build your own.
All it takes are two wireless ethernet bridge radios and a crossover
ethernet cable. They're also becoming common in wireless mesh
networks to solve the same problem.

Short opinion: Repeaters usually suck.

Interesting, now that you mention "marginal" and "G" in the same
sentence.

Yep. Your laptop should give you an indication of connection speed.
Move some traffic, such as streaming audio or video, and start walking
around. Look at the connection speed, which will go up and down. I
doubt if you can maintain 54Mbits/sec farther than about 5 meters away
from the access point. With lots of reflections in the room, probably
less. Once you go through a wall or two, your speed will drop down to
much lower speeds. That's marginal. No way are you going to maintain
a MIMO speed connection with such an arrangement.

I believe that the TiVo's wireless antenna is only a "G" in
the first place.

Yes. The AG0100 usb dongle is 802.11b/g with 54mbits/sec max.

I'm about to reply to John Navas's reply, in which he recommends
powerline networking. I gather that would cost a little bit.

Before we dive into alternatives, I suggest you consider your
performance and bandwidth requirements. If you're moving video files
between your DVR and computah or running a video server via ethernet,
you're going to need LOTS of bandwidth and performance. I just setup
one of those that required gigabit speeds to be usable. You won't get
that with wireless, but you can get that with CAT5. You also won't
get it with power line, phone line, zip cord, barbed wire, etc. You
can with fiber, but you won't like the price.

Chart of common routers and their maximum performance:
<http://www.smallnetbuilder.com/component/option,com_wireless/Itemid,200/>
The WRT160N is listed at 43.9mbits/sec max (that's with MIMO active).
You won't get over 25mbits/sec with 802.11g only. Incidentally, there
is quite a bit of really good stuff on this above web site.

The problem with power line networking is that there are several
technologies available. Basically, there's
14mbits/sec (HomePlug 1.0),
85mbit/sec (Homeplug 1.0 Turbo)
200mbit/sec (HomePlug AV)
speeds. The first is useless. I can't seem to find any benchmark
results on the others, but I doubt if you'll get anywhere near the
specified maximum.

Incidentally, for running performance tests, see IPerf and JPerf.
<http://sourceforge.net/projects/iperf>
<http://sourceforge.net/projects/jperf>
<http://openmaniak.com/iperf.php> tutorial

Hmm. I'm not good at doing these conversions. The last I checked,
our DSL speed was 384k-1.5M/128k-256k, and DSLReports.com just told me
I was doing 1,271 up and 314 down.

Ok, I can work with that. Your maximum DSL speed is about
1.5Mbits/sec. If you use a direct wireless connection, you'll need an
error free connection speed of no less than 3Mbits/sec. The closest
is 5.5Mbits/sec. If you add a repeater, you'll need at least
6Mbits/sec. The closest 802.11g speed is 9Mbits/sec.

That works if everything you do goes through the DSL connection and to
the internet. That's possible but rather improbable. For example,
wireless printing, Tivo to PC, PC to PC, running backups over the
network, shared file/video server, and such are all local traffic that
will need to go MUCH faster than DSL speeds. Therefore, with your
office arrangement, I suspect that you'll need much more than the
minimum of 9Mbit/sec thruput.

Our DSL speed is probably an important factor for most of the
transfering we'll be doing (something from the internet to a computer
or a TiVo). I'm pretty sure that TiVo-to-TiVo transfers will be less
than 5% of our usage.

Is that 5% of the number of megabloats you're moving, or 5% of the
time? I think you'll find the file sizes to be rather huge and the
speed requirements rather high if you're playing video server.

Do you have a Tivo 2 or Tivo 3?

I mention all this in case it affects your thinking in terms of the
numbers.

I always think in terms of numbers. Units of measure are also handy.

That's a fairly typical mix. Netflix is a big bandwidth user.

Try watching Netflix online on your laptop with a not so great
wireless connection. For extra entertainment, try doing something
else with the wireless at the same time. That's important because
wireless airtime is a shared resource. If two wireless clients are
doing something at the same time, then the available bandwidth gets
split (not necessarily equally).

I should mention that there's no particular reason the WRT300N router
has to stay on the far west side of the house once we disconnect the
DSL line over there.

I think it might be handy to have wireless at both ends of the house.
You have the hardware so use it.

In fact, I was thinking it should go somewhere
in the middle of the house, somewhere that it can wirelessly receive
the signal from the other router, and be located centrally enough to
transmit it around to the other devices.

That would work were it not for the number of walls in the house. If
you think you can get adequate coverage from a wireless router in the
middle of the house, by all means, try it. However, if you're going
to run CAT5 to the router half way across the house, I suggest you
finish the job and go all the way from end to end.

Rough estimate of distances...

East: DSL Modem. Signal starts here.

Go through 2 thick walls (or through a door and around a couple
corners).

Middle: 25 feet away in a straight line (through thick walls). Or
about 40 feet, through the door and around corners.

West: About 20 feet further than Middle.

South: 25 to 30 feet away from Middle. It may also get a more direct
signal from the first router shooting out one window, around a single
corner and in another window. So, rather than traveling about 60 or
70 feet through thick walls, the signal might have a shorter path
going out the window and about 40 feet.


25' or 40'

West -- 20' -- Middle --| |-- East
| | |
| ----
25'
|
|
South


I hope that conveys it.

Yep. Too many (thick) walls and no single ideal location. Going
through windows might work, until something gets in the way. Watch
out for low-E window coatings. They block RF. It might be possible
to locate the single router in the South part of the house, and shoot
through windows in both the West and East ends. That might work for a
fixed antenna located in the window, but I doubt it will work for the
laptop with an internal antenna. It's easy enough to try.

I would normally suggest installing directional antennas but your
existing MIMO routers have non-removable antennas.

1. Run CAT5 ethernet cable between the two routers. This is the best
and fastest alternative.

This might be a good idea, although I'm not sure what you mean by
"fastest."

With gigabit routers at each end, and less than 100 meters of CAT5,
you can move data at almost 1000mbits/sec. That's really handy for
giant video file transfers and running video servers. Both your
existing routers have built in gigabit switches. With the usual
10/100mbit/sec ethernet switches, you'll get a bit less than
100mbits/sec. Reminder: the BEST you can do with wireless 802.11g is
25mbits/sec.

It would surely take longer to go under the house (or pay
someone to go under the house) and run CAT5 ethernet cable than to
just stick the WRT300N router in the middle of the house and let it
receive the signal wirelessly.

Ture. Try the relocated router in either the Middle or through
windows at the South. It might work well enough for internet traffic,
but any large file transfers across the wireless LAN are going to be
painfully slow.

Running CAT5 under the house is a messy project. That's what kids are
for. The nice thing is that it always works (unless the kid pounds a
staple through the cable) and requires no tinkering, adjusting,
configuring, tweaking, and swearing that's common with wireless. If
you add up the elapsed time involved, deployment time might be
comparable.

Or, by "fastest," do you mean the solution that would provide the
fastest transfer speeds once we get it wired up?

Fastest transfer speeds. Fast is fun.

<http://wireless.navas.us/wiki/Wi-Fi_How_To#Use_a_wireless_router_as_a_wireless_access_point>

Bookmarked. Thank you. Does that only work if the second wireless
router gets its signal from a cable, rather than wirelessly?

Wired via CAT5 ethernet. However, I forgot to mumble something about
WDS repeaters. Looks like the WRT150N and WRT300N do NOT support WDS.
Never mind.
<http://en.wikipedia.org/wiki/Wireless_Distribution_System>

I'll have to read up on setting channels, but I suspect it'll be easy
enough.

Yep. It's on the wireless page of the router configuration. It's
only necessary to change it in the routers. The clients will
automagically follow the change.

(Having just looked at the Linksys admin screens under "Wireless >
Basic Wireless Settings," I see that I'll have to set Radio Band to
either Standard or Wide, rather than Auto, then manually set the
Standard and/or Wide Channels.)

All those have to do with MIMO (802.11n). If you use "wide", it's
fixed to channel 6 as it now hogs the entire band. The only way you
can set the channel is to use standard (narrow) bandwidth.

If a wired run is truly the best way to do it, then I'm still favoring
the method that doesn't involve someone going under the house.
Powerline networking sounds good...

I don't have any specific recommendations for power line networking
equipment. My guess is about $100 per end. For $200, I'm sure you
can bribe the neighbors brat into getting filthy under the house.

Can I meet all my needs with no new cabling and no new devices, simply
by putting the WRT300N router in the middle of the house?

My guess(tm) is that it will work going through windows at the south
end of the house, but will be flaky and unreliable going through walls
in the middle location.

Or will I
suffer over the longterm enough that it's worth spending some money
(perhaps to have a professional run an ethernet cable from the east to
west side of our house)?

I don't see that the decision has to be made immediately. You have
enough equipment to do a live test for the wireless arrangement. Try
it, see how it plays, see how stable it runs, and make the
determination. If it's as bad as I predict, then run the wires.

--
Jeff Liebermann jeffl@xxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.