MR74s On a Dock + Which Antennas?

[mrsgrt]

I'm trying to put in a new wireless solution for a client with an outdoor dock.

The area of coverage that we are trying to support is approximately 40m x 100m.

Both Marine Vessels and the open building will need to be able to reach the signal.

I'm thinking of putting 2 MR74s back to back atop a pole located at the X in the below photo.

One MR74 will point towards one end of the dock while the second will point towards the other end of the dock.

In this case, should I use omni or sector antennas? How many would you recommend for each MR74?

Any input would be greatly appreciated. Thank you!

[bucky919]

You will probably want a omni to cover the closer boats, depending on the height there mounted, then sectors to reach alittle further away.

[mrsgrt]

Thanks for the response! I wasn't sure if I should use omni or not as they would be back-to-back and might interfere with each other. Was thinking of using sectors on bottom and sides but nervous about the range. I might have to go back to the drawing board regarding number of APs and placement.

[PhilipDAth · Accepted solution]

Is it at all possible to put in more MR's?

I think you would get excellent results using three MR's using omni antennas, spaced around 25m, 50m and 75m along the dock.  You could potentially run power and fibre out to the one at 50m and then put in an 8 port PoE switch (such as an MS120-8P), and then run only copper to the 25m and 50m spots.  The units at 25m and 75m wouldn't need to go on a big pole.  Worst case they could go at ground level, but I think they would be fine at "hand rail" level, 1m or so off the dock.

I think you would get reasonable results overall using two MR's using omni antennas, spaced around 33m and 66m along the dock.  You will probably get some places with poor or no coverage still.

I'm been deliberating using patch antennas, but I think you wont get a good result from the location in the diagram.  That is because you have vessels almost 180 degrees either side.  I think the coverage in those wide fan areas might be patchy.

I also think using omni antennas from just this one location will result in very patch coverage at the ends.

Also note that water kills RF signal by absorbing it.  Your objects are all floating above the water, so it shouldn't be too bad - but it would make me nervous doing the deployment from one location.  I would be worried about the signal dropping off much faster than in a land based environment.  So I would be pushing for my first suggestion.

[PhilipDAth]

Any any of the vessels own by the company operating the dock?

If so, you could also consider putting an access point on a few of them running in MESH mode which will punch out the coverage circuit at the expense of performance ... but note of course the coverage will vary as the vessel comes and goes.

[mrsgrt]

Thank you for your suggestions! I haven't worked with outdoor MR's in such an open area before.

We originally wanted to use 3 MR's but the budget the client insisted on is already depleted with the 2 MR's and various Antennas. I'll see if I can convince them to increase it as 3 MR's would pretty much guarantee quality.

Would the current placement with sector antennas to the side and bottom be okay or would the range be really poor?

Otherwise, it sounds like placement at 33m & 66m with omni might be the most cost effective way to go for them if I can't get them to go with 3 MR's.

I didn't realize water kills RF signals that much more than land. I'll keep that in mind for this project and will be sure to bring that up to the client when I try to convince them that 3 is the way to go 😉

They do own the vessels on the dock but they're back and forth pretty frequently so we can't really count on them.

[PhilipDAth]

ps. I should mention I have previously deployed WiFi into a ship yard with multiple docks.

If you don't go with my suggestion I would recommend you really lower the customers expectation of how well this will work.

Perhaps break the project into phases.  Get them to commit to putting in a certain number of AP's (so you know how to space them out).  Then do phase 1 initially and just put in 1 or 2 AP's, wait till there is more budget and do the next phase, etc.