wireless distance

[javahouse88]

I am planning on hooking up 20 different sites ranging from 8 to 15 miles with Aironet 1310 wireless bridges. I am wondering how important the height is most of the locations already have towers that are 150 tall and some only have towers that are 30 feet tall. On there excel sheet it says that the required height is 72 feet. I am wondering if it is required for both locations or could I get away with one that’s tall and one that’s a little the sheets recommendation. Also what is the thruput that I could expect with this type of bridge it says on the excel sheet that I can expect 11 mbits over 13 miles is this realistic or will I get something lower.

[cisco]

I have acheived 13+ miles at 54 Meg 802.11g distances without the use of amplifiers while using the Linksys WET54G 12mw radio at the remote locations and a non-cisco AP at my base. My tests using only 1310s for the AP and client did not even come close to these connection speeds at 13 miles. As far you expecting 11 mbits at 13 miles, it can be done.

There are some important issues that you need to address.

Bottom line, all the sites must have a clear line-of-site to your Base Access-Point 1310 radios.

What will your primary Access-Point consist of? Are you planning to use a single omni antenna on the AP or will you have several APs at the base statioin APs using sector antennas? I don't think an omni will work for your base station AP, even if you use an amplifier.

What ever you use for your client 802.11g radios, you will need a very good high db directional antenna at 13 miles.

[jonah.scott]

The plan right now is the base will have 2 APs with dish antennas pointed at the two closest branches both at 8 miles the base is on a 200 foot grain leg and the two branches that I am trying to connect both have 30 foot radio antenna’s. The Cisco excel sheet says that the minimum height is somewhere around 60 to 70 feet would I be able to get around the fresnel zone or would I have to extend both radio towers to get a good connection.

The rest of the locations would be reached by daisy chaining thru to the closest branch all having 2 boxes at each location one towards the central base and one to the next location. I don’t think that there are any locations that could use a sector antenna so is this the way to do it or is there a better way. The whole network covers over 100 miles and there are no links that will be less than 8 miles.

The wet54g would that be able to do go 30 miles at any speed reliably it will only be connecting 4 computers and now is connected by a 56k frame relay so it doesn’t need to be fast. Also is the security the same as the aironet equipment.

Any input on a better way to set this up is greatly appreciated.

[cisco]

If everything is a point to point (instead of point to multi-point), you should use only dish antennas.

I dont think a WET54G will do 30 miles (802.11g OFDM) without some serious antennas and possibly an amplifier on it. The WET54G in only 12 milli-watts using OFDM modulation and 40 mw using CCK modulation. My testing with the WET54G radios was using a 19 db antenna and they were connecting to a Vivato AP. The connection was good - but I was unable to get that kind of distance using a Cisco 1300 for the AP. If you decide to try the WET54G for 30 miles, consider at least a 250 mw amp then see how the math works out.

I think if I were you, I would try high gain dish antennas and have a line on some amplifiers if they end up being needed. For the distances you are talking about, you may need to take it up to the maximum legal power.

You may want to also consider something in the 5GHz band.

[jonah.scott]

Is there a way to hook up two antenna's to one recever to do point to multi-point or is there not enough power to do something like this

[cisco]

My thoughts are - If you need two antennas (aimed different directions) then use two radios.

[jonah.scott]

Thanks a lot. I am kind of a newbe at this if you havent been able to tell

[sorvarit]

In theory you could use two antennas on one BR1310 or similar by using a antenna splitter, but this will also reduce effect on the antennas.

We use a BR1310 as a repeater on a hill for a link that has to take a 90 degree turn. This is done with a splitter and two 24dbi grid antennas pointing at each direction.

The first hop from the root-AP (also BR1310) to the repeater is only 1Km and the next hop to the destination is 4Km and we get full speed (54Mbps) and good link quality. Talking about your distances here in Europe we can forget. This if we want the link to be legal.

Didnt even know if our links would work before ordering the equipment, but took the chance. The antennas was already in place becaused the Cisco boxes replaced some older Breezenet bridges. The only thing we had to do was replacing pigtails for the N-connectors that was hooked up to the antenna cables. If that hadnt worked we could always used them another place:)

My advice is to order a set and some high gain dishes and do field tests if you can.

Orjan