Wireless bridge 500ft - what setup is the best

[Martinni]

Hi, customer need is to have wireless LAN extension between two buildings at 500ft distance.

My suggestion is to use 2x MR86 + 4x ANT-MA-27

Will this be sufficient, or should we start looking at other vendors?

Maybe someone has already this setup and can help.

Thank you.

[PatWruk]

When trying to do something like this it would probably be better to use Point-to-Point radios instead of wireless access points. If you can get the distance between the 2 buildings you'll also get that distance to the sides leaving a huge footprint of your wireless network.

[Martinni]

I do understand this. There are other things that prevent us to use non-contracted devices.

Question is, if this will work with proposed devices. 

[rhbirkelund]

I've done this using MR76 with MA-ANT-21/23 sector antennas, so it should be possible. Although I had to turn enable lower MCS rates, inorder to keep a somewhat stable connection.

I'd recommend reaching out to your sales rep, and and working with him/her by getting a trial setup first, to do a PoC, before purchase.

[GIdenJoe · Accepted solution]

Using this site https://www.everythingrf.com/rf-calculators/free-space-path-loss-calculator I have calculated the following:
500ft is about 152 meters.
Using channel 100-104-108-112 (I used the highest of these channels for the free space path loss, ch 112) equates to 5560 MHz.

The MA-ANT-27 has a gain of 12 dBi.
I'm not sure what region you're in but the European rules are the strictest when it comes to Tx Power so I'll assume a max EIRP of 30 dBm on this channel which means you can transmit on 18 dBm.

Using these inputs in the calculator I come to a free space path loss of 67 dB.

Since the gains are already included in the calculation I now have to do 18 - 67 = -49 dBm which is quite high and should not be a problem to receive well enough signals between both buildings.  You even have over 20 dB of fade margin in case of bad weather.

From another calculator on that same site https://www.everythingrf.com/rf-calculators/fresnel-zone-calculator I calculated the fresnel zone of 1.4 meters or a bit under 5 feet.  This is the radius around the line you would draw between both antennas that has to be clear of obstructions to not negatively affect your signal.

The only thing I do question however is the use of an MR86 instead of an MR76.  If there are no reflective surfaces you won't gain any spatial streams to augment the speed.  So you could basically use an MR76 instead and only use 1 antenna per AP between the buildings.

[rhbirkelund]

Do be aware though, that those channels are DFS channels, and thus you may be subjected to frequent DFS events.

It might not be relevant in a metropolitan setting, but if you're going to need the wireless link near an airport or harbour/ferryline, you'll might get a lots of events.

[GIdenJoe]

In Europe we don't have a choice.  The lower channels 36-48 are simply not available on outdoor AP's.
So DFS channels is the only choice we have.

[rhbirkelund]

And that is entirely true.

I'm pretty annoyed that I can't use UNII1 channels where I've put this Mesh, as it is going across a harbour, so I'm getting DFS events on all channels that the MR76 is using.

[Martinni]

This is for US, so I think it will be easier, thank you all for answers and discussion.