A question of range (802.11n) . . .

[weh]

I realize that one cannot expect extended range with a standard 802.11n router, regardless of brand (or manufacturers' Madison Ave hype); however, would it be possible to extend the range between the router and client by using a pair of external parabolic antennas?

Specifically, this one: 2.4 GHz 24 dBi Die-cast Grid Antenna.

The situation is that a friend has a wired network in his home and wants to be able to use a computer in a barn on his property that is approximately 175 feet away from the house. It is not feasible to run cable as it would have to cross a state road that divides the property.

I figured that he could replace the wired-only router he is currently using (a D-Link DGL-4100) with a new 802.11n router (we'd pick one with high 2.4GHz performance that also has detachable antenna connections rather than altering a router with internal antennas) and use the pair of parabolic antennas -- one at the house, the other at the barn, connecting the second antenna to the barn's computer (uses an Intel 5300 mini PCI/e card and has antenna connections on the rear of the chassis).

Is this a reasonable approach? Any other suggestions? I'd hate to buy all the equipment and find it useless.

 

[DaveMcLain]

I use that exact antenna to extend a wireless network from one building to another with great results. The only thing is that I'm not sure if you'll be getting any advantage from any sort of N hardware and here's why....

In my case I'm using a Linksys WRT54G V5 running DD-WRT mainly so I can set it to send and receive using only one antenna. The router is set up to work as an AP only and I have it mounted inside of a weatherproof enclosure powered by using a Linksys POE kit. The antenna is mounted on a stand, connected to the WRT using the right pigtail to and carefully aimed toward the other end of the link. In this case right now I'm using a Netgear WGR-614 V8 also running DD-WRT set to "client bridge" mode. That box connects to a couple of wired PC's and one wireless AP(D-Link DIR-655 set to be only an AP and not a router).

I need to take a few pictures of this setup but it's making a long shot across about 200ft of yard with a few trees to a house where it goes through several plaster walls to reach the client bridge which by the way has stock antennas.

Signal quality in DD-WRT is generally about 35-40% and the link is very fast and stable. The data rate is generally shown to be 36-54Mbs.

I don't know if N will help you just because if you do it like I'm set up you only need one antenna at each end of the link. This antenna is VERY large so having two or three could be tough to get packaged well.

I have both of my boxes, the AP and the client bridge set to use the DD-WRT default of 71mw but this is more power than is necessary with this antenna. Clear line of sight if you had two of those antennas you could probably do 1/4 mile very easily. After all in my setup I only have the high gain dish set up at one end of the link and it still works just fine.

Overall this setup has been quite reliable and I've never had to reset the AP. The client bridge side has needed a reset a couple of times over the past 6 months or so but I think that's mostly just due to powerline glitches. That end is not on a UPS as is the other end. DD-WRT can also do a repeater bridge mode where the client can also accept wireless clients of it's own and act as a wireless repeater as well as a bridge. While this allows you to get by with only one box if you want wireless at the end of the bridge I could not get it to be stable enough so I now just use two boxes.

 

[thiggins]

I'd suggest a pair of inexpensive antenna/bridge units made for this application. See this thread for product suggestions.

 

[DaveMcLain]

Today I took a few pictures of the installation. Here is a picture of the antenna on it's stand. It's set up under a car port at our workshop. This shop is an automotive machine shop and we do engine building etc. This area is used primarily for storing some stuff and unloading engines. I also have an engine dyno and we do testing in the same location.

http://i40.photobucket.com/albums/e218/DaveMcLain/Wifi Link Photos/Antenna.jpg

Here is a picture of the weatherproof enclosure that came from Lowes' or Home Depot. I found one that could house the WRT54G with room to spare. I simply drilled two holes and hooked everything up inside. One hole is for the Eithernet cable and the other for the antenna pigtail. Those holes were sealed with some RTV silicone. Also in the box is the Linksys POE module which is needed to do POE with these Linksys boxes. The lid has a gasket which makes it watertight when screwed down tightly. I want to make and install a bracket for the enclosure so that it can be attached to the antenna mast but it's just been too cold and nasty to mess with it right now.

While you can order the antenna with a connector that will hook directly to the WRT I think it's better and easier to just order a pigtail with an N connector on one end and the RP-BNC connector on the other. Losses are minimal with a cable this short anyway.

http://i40.photobucket.com/albums/e218/DaveMcLain/Wifi Link Photos/weatherproof.jpg

This picture shows the actual "shot" that's being made by the antenna. It goes from the workshop all the way over to my folks' house. In the picture you can see the house. What's not shown is that the client AP is not right at the end of the house in the picture but actually a couple of rooms and plaster walls farther away.

http://i40.photobucket.com/albums/e218/DaveMcLain/Wifi Link Photos/longdistanceshot.jpg

Lastly here's a picture of the boxes that are inside of the house in the office. On top is the Netgear WGR 614 V8 that is running DD-WRT firmware and set up to work as a client bridge. It services two wired computers and the D-Link DIR-655 which acts as the wireless AP for the house. It's configured to just be an AP and it does this very well.

http://i40.photobucket.com/albums/e218/DaveMcLain/Wifi Link Photos/Image117.jpg

While this is a hodgepodge of inexpensive equipment it works very well. 90% of it was purchased used off of E-Bay etc. About the only stuff that was bought new for this purpose was the antenna, pigtail, and the out door box for the WRT54G. Total cost was probably less than $100. If you shop around carefully you can usually buy those WRT54G V5's or V6's used for about $15. Same for the Netgear, it really makes no difference as long as they can be configured as needed. I'm using DD-WRT on both of the boxes that make up the link because I need to be able to set the main AP on the high gain antenna to use only one antenna(RT in this case). And I'm using it on the other end just so that I can make the WGR-614 work as a client bridge and that's not available on any standard el-cheapo router that I've used.

This project and other wifi projects have been a lot of fun for me. It was a challenge to get it working but not difficult either. It's fun also because it's been reliable AND cheap!

 

[kevinqian]

nice work dude. i suppose if you used a pair of those rabbit ears, you could get very reliable 99% uptime with good speeds.

 

[weh]

So, rather than attempt to make a wireless router with a high-gain external antenna and the wireless client card with a similar high-gain external antenna do the work, I'm better off buying a pair of outdoor bridge/radios with integrated antennas and connecting one to the existing router and the other to the computer in the barn?

Somehow, that seems way to simple. Thanks for the suggestion.

 

[DaveMcLain]

I think it would work as you're saying very easily, yes. I believe Mr Higgins' advice is right on target if you don't want to mess around with 3rd party firmware etc in order to re purpose other hardware to do the job.

In my example the outdoor AP that's connected to the big antenna is not the main router. The main router is a WRT54G-TM that's inside of the shop and it does the routing for the whole network. It just has the stock Linksys antennas to allow it to give wireless coverage inside of the shop that's independent of the long distance link. The outdoor AP is dedicated to just that one task of passing data to and from the house.

While it might seem strange I've found that it works fine to have a really high gain antenna on one end of the link or the other. And in my case the signal is plenty strong even with the Netgear AP with stock antennas on the house end. In the past I've had other boxes in that position including ones with higher than stock gain antennas and while it increased signal strength slightly it didn't make any real difference in performance. If the link was a whole lot longer then it would start to make a big difference. After using that antenna I really believe that if I had two of them I could stretch a link like this one 1/4 mile easily and reliably it's THAT powerful.

 

[saturation]

What kind of throughputs are you getting on your setup, DaveMcLain ?

 

[weh]

My friend doesn't use wireless in his house at all. He has 3 computers, all of them wired with gig/e to the DGL-4100. What I had originally conceived was simply replacing the router with a wireless model and treating the barn computer as if it were a laptop in the house -- except, both the wireless router and the client computer would have had high-gain, directional antennas instead of the ones with which they shipped.

The pair of bridge radios with built-in antennas makes the system more versatile and their cost is less than buying a new wireless router, the two dish antennas and accessories.

We're ordering a pair of these: EnGenius EOC2610 / HD26912 (here & here) -- plus J-mounts, outdoor cable, et cetera.

 

[DaveMcLain]

I just looked and the data rate shown on each of the boxes is 36Mbs. It's been a while since I've speed checked it but it seems like it was doing around 10Mbs quite easily. Transferring files from one of the office PC's out to a shared drive in the shop happens very quickly and is not glitchy. The internet connection at the shop measures about 3.2Mbs most of the time and stuff like internet video streaming on CNN and similar sites works fine.

 

[saturation]

Its good to know it works well!

I just looked and the data rate shown on each of the boxes is 36Mbs. It's been a while since I've speed checked it but it seems like it was doing around 10Mbs quite easily. Transferring files from one of the office PC's out to a shared drive in the shop happens very quickly and is not glitchy. The internet connection at the shop measures about 3.2Mbs most of the time and stuff like internet video streaming on CNN and similar sites works fine.