300metre wireless network setup

[bluesky]

Hi folks, we have a wireless networking problem i'm hoping someone can shed some light on......

We are trying to extend wireless internet at a work site to some neighboring work site buildings. The target buildings are about 300metres from the source building.... and the target buildings are located fairly close together in a horseshoe fashion. From the source building, the target buildings could be all hit within a "90 degree beam".

Now we have tried a couple things already.... including a cantenna hooked up to a us robotics access point at the source building. This setup brings in a low signal and works for approximately half of the target buildings on the their laptops.

We did try a 18db omni roof pole mount with 30' LMR400 cable.... and signal did not even reach the target buildings at all..... even with a 500mw hawking booster on it.

We also tried putting on a hawking 500mw booster onto the access point with the cantenna.... and this improved signal strength somewhat, but still not useable for everyone or dependable for anyone.

Obviously we have been trying to do all of the legwork from the source building so that users in the target work site buildings need only a laptop to access the internet..... although it's looking like this setup is just not going to work.

My question is this.... what is the best way to improve the situation? If we added a directional antenna and repeater to the target buildings, could we then rebroadcast the signal to the rest of the target buildings easily?

I would appreciate hearing any and all suggestions regarding this. Saving money is not really an issue here.... whatever it takes to set up a reliable service is the key objective. Feel free to point out things like boosters, parabolics, directionals, access points, etc that would work.

Thanks.

[Whyzman]

Saving money is not really an issue here.... whatever it takes to set up a reliable serviceI've, perhaps, a little bit different take on what you are attempting to do. The research I've done while looking at your situation raises a number of question...especially based on your failed attempts.

You've stated that you're willing to spend what it takes to accomplish your goal but I don't know if that also includes "wasting" money to get there. My suggestion would be to hire a consultant familiar with all the resources available, or to hire a company that would be willing to guarantee the setup to work.

You can continue to throw money at the problem and perchance find a solution that works, but I would contend that your situation is not unique and that there are folks who deal with solving your type of problem on a daily basis...

My 2 cents worth... :)

[Variable]

You need to ditch the Omni and get a sector. You could cover the buildings with a 120 degree or possibly a 90, if it is far enough back. Are you using the coax to route from the AP to the antenna?? You will lose a lot of power that way. You should have the AP right next to the antenna with a short pigtail for minimal loss. It isn't just the cable; it is how it is run and the connection. Shorter the cable the better. You can buy a power over Ethernet adapter and run the power and data from the internet connection up to the AP and antenna.

Noise is big issue outdoors and so is building material. That is why a narrower beam antenna works better. It has more focused power and less reception of noise. You may need to put a directional aimed at your sector on each building then route a cat5 to a repeater indoors. Just depends on the set up. There is no guarantee any antenna will penetrate the buildings.

Sectors and directionals will reduce noise. You should also note placement. Radio signals come out of the antenna in a football shape; it is called a Fresnel zone. Objects close to the antenna impact the Fresnel zone a great deal, that's why putting them up high and away from buildings is a good idea.

You need to start with a link budget for your antennas. You can look below to start. Remember that there are many variables that can affect the numbers.

http://huizen.deds.nl/~pa0hoo/helix_wifi/linkbudgetcalc/wlan_budgetcalc.html

[bluesky]

Thanks for the info fellas..... the sector antenna with power over Ethernet seems like a logical way to do this. That way we can get the sector outside the building without running a bunch of lmr400. Plus a 120 sector antenna would work out nicely to blanket the desired areas.

I've heard conflicting stories about the return path of the signal, however. I have always figured that the receive strength must be of comparable strength to the transmitting strength in order for both devices to "talk" to each other. However, i have heard others refuting this, saying as long as the transmit power is adequate to reach the receiving unit, then the link is established and does not require the higher signal power output to return the signal. So what really is the proper answer to this?

[bassman]

Is there any type of communication wiring between the buildings at this time? if you have existing hard wire, possibly not all of the pairs are being used. You need 2 pair for a network connection. You could then hardwire an access point in the target buildings and have wireless from there.

Aside from that, have you been here (http://nocat.net/)?

[Variable]

Transmit power and receiving power for many radios are bound together but not always. Think of transmit power as shouting louder and receiving power as having amplified hearing. You only need to shout loud enough from the sector so that the client radios can hear. The client radios should shout back loud enough so that the sector can hear. I know this sounds simple but the problem is noise. If there are other radios nearby and your sector and clients are transmitting at full power, other radios see this and try to bump their power up to compensate. You really only want to transmit and receive on the lowest amount that works well. A sector and directional clients will limit noise because their power is directed and they hear less noise from around them. If you can tune both transmit and receive, then you simply tweak the settings from low to high power until it works well. If you are isolated and no other radios show up in your scans you can pound away at max settings. You can also look at a solid signal as bandwidth, normally your sector to clients will be pulling down more data than the clients will send back. So a strong sector to client signal will give you better real world performance. Many times you will need to boost the client transmit power but you do not need higher receive power because the sector is elevated and focused. Boosting receive power on the sector is fine as long as their is not a lot of noise. Think of each link as totally separate. Sector to CPE (the client radio) is not the same as the link from the CPE to the sector and do this for each CPE. One CPE may be tuned one way because of location and another may be tuned differently.