Linking Two Buildings - Wireless Options

Hi all,

Looking for a solution to link two buildings (approximately 50m apart line-of-sight), that have NO way of having a hard-wired connection between them.

My current thoughts are a pair of wireless 'N' access points in "Bridge" mode, with each one having it's own directional antenna.

Looking around, many of the access points I can see have two/three aerials - how might this work for this situation? Should I get two/three directional antenna's for each end unit?

What'd be considered a "good option"? Looking at around £5-600 for this (but if the "best" solution ends up being a little bit more, then I'm sure that'll be fine) - the higher the throughput we can get, the better.


Cheers!

Garry

I've just ordered a couple of DrayTek AP700 wireless access points, plus 4x 16dBi gain panel directional antennas.

They should be delivered within the next couple of days - so will see what kind of result I'll get from that lot of goodies once they're configured.

Yeah for 50m that should be fine, i was on the verge of recommending some proper PtP wireless link stuff but that only really works over 1KM+!

Let us know how you get on I'm installing some directional wireless kit at a Hotel later this week, to cover the external buildings.

Just curious Confused and Duke, I guess what you are both doing is for like a contracted project job? Currently learning about this in College, more the software side.

Our company has just purchased another, and they are moving into another unit within the same business park as us - but across the carpark, and there is no way we can run a wire between the two.

The systems in both offices will be linked - so wireless is the only option.

The kit we've purchased is a total of £248 - if that's good enough, then great. If not, then we'll find another use for the equipment or sell it on, and will re-evaluate the situation and hardware again!

Hopefully some/all of the kit will be delivered tomorrow and I can start to have a play - else I'm not in again until next Tuesday, where at least if I've had a play tomorrow, I'll have had a few days to figure some other bits out!

Will try to get some pictures during/once it's all sorted out, and some of the results, such as speed/ping/packet loss etc tests - both with just the units, plus the directional antennas too (which should help justify to those in charge at my place the cost of the items!)

GregI said:

Just curious Confused and Duke, I guess what you are both doing is for like a contracted project job? Currently learning about this in College, more the software side.

Click to expand...

Yep, I look after their computers and they want to expand the wireless network, which currently only covers in the indoors, to cover some external buildings. I did the same thing for another hotel nearby as well.

Basically I just get similar equipment to what the OP has - a decent access point which is cabled back into their router/switch and then a suitable antenna which I tend to use DLink or Netgear and the pigtail connection back to the AP. If you want to cover an area (either indoor or outdoor) then you can just point the antenna in the direction to cover, although you need to check the limits of the width/height of coverage, but building to building you just get the same equipment again and have them point to point and plug the AP into switches on either end. I've done this with a previous company I worked for, which were in the same situation as the OP, as they had two buildings on a business park to connect up.

Oh nice. Thanks. Cool to know. I want to try and do the same type of thing.

Good luck

The access points have arrived - and they've been configured in Point-to-Point bridge mode - very easy to do.

Will be trying them out with their standard 3dbi omni-directional antennas first off, using iperf to measure throughput and jitter across the bridge.

Then, once the directional antennas arrive, I'll repeat the process with those in place of the standard antennas.

With the standard DrayTek AP700 antenna, have been able to get approximately 40 Mbit/sec throughput with a single sustained file transfer, and about 85 Mbit/sec with multiple simultaneous file transfers when the two units are in the same room as each other.

Putting one in each building (inside, going through a couple of thick brick walls and a metal roller shutter door) the single sustained transfer goes to about 4 Mbit/sec (I didn't check the multiple simultaneous)

Obviously this is "worst case" scenario - both units indoors, no line-of-sight, and through multiple thick walls.

The directional antennas have yet to be delivered, so I can't test the throughput with those yet.

I take it the directional ones you will mount externally and point to point though? So should be good.

Yeah they will be mounted externally, and pointing directly at each other.

Just tested between two machines plugged into the same 10/100 switch - overall transfer - 80-85 Mbit/sec

So - my wireless solution is currently working at the full capacity of the 10/100 network that will be either end.

Interesting solution!
Will be interesting to see if it works.

What kind of throughput would you be seeing if you plugged into gigabit links at either end? (if possible)

I was looking for wireless lag-free connection between rooms couple years ago and seen this: http://www.netgear.co.uk/wnhdeb111.php
It looked ideal for my gaming needs but was £90 new. Managed to get pair of these from well known auction site for £85, set them up as a bridge and they're brilliant. But that's between rooms in a same flat, not sure about 50m. They are very reliable too and ridicilously easy to set-up. Try google or something to find out about distance.

The multiple antennas are for 802.11n's MIMO. This takes advantage of the scattering present in typical in-building environments. For line of sight, MIMO doesn't offer significant gain.

Confused said:

... plus 4x 16dBi gain panel directional antennas.

Click to expand...

I expect you'd get similar performance from only connecting one of the Tx/Rx antenna ports on each box and ignoring the others.

We've used optical (laser) point to point links for inter-building connections. Fast, but not so robust in heavy rain or fog!

The network ports on the access points I've ordered are only 10/100, so no real gains there from being plugged into gigabit switches - but our main network infrastructure is still only 100 anyway at the moment.


We decided that as the access points have 2 antennas on, for the sake of a few pounds now, it'd be pointless not using both - at least then if one does go south in the future, there's still the other to take over!

Remember to test in heavy rain too! Rain fade can have a drastic effect on signal strength and quality.

Also make sure your antennas are mounted high enough to avoid the fresnel zone.

My install went well. The directional antenna covered the external buildings nicely.

Our antennas have gone up on the outside of the buildings (will try to grab a couple of photos later on)

Our end is powered up and connected to the LAN, the other end (in the new unit) is still having power/network infrastructure being installed, so can't get over there to test it out yet.