Puerto Rico: Long Distance Wifi Link

Does anyone have any recommendations for building a long-distance wifi links to help restore some basic communication links in Puerto Rico?

Even better if you have some hardware you would like to donate.

I'm looking for something that can link between Puerto Rico and the Dominican Republic which at a minimum is 80 miles, but more realistically 120-150 miles.

Directional Antennas?
Solar Panels?


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I'm no expert but that's a long way and you'd need a lot of equipment. Is there already signal coming from DR?

You'll have to get up high to get a line-of-sight. But that's just one small part of the equation.

PR must have undersea fiber cables???

Microwave might work over those distances but I'd think you'd need a LOT of power for TX.

This is a deep-pocket problem, or in other words it will require a lot of money.

There are many parts of PR which don't have cell service and probably won't have it for a while, there are still some counties that are reporting 100% cell phone towers down, and many counties in the 75-85% range.

Height is not a problem, there are places close to the coasts of both islands that are fairly
high. I plotted the path here and it looks like line of sight is not an issue.

I'm sure that San Juan will be up and running soon, but many places especially on the West Coast will be offline for many months.

There was a group set up a ~240 mile wifi link in 2007 using a pair of WRT54Gs.

If you want something reliable it'll cost some money.

So you have signal already coming from DR?
PR mostly served by undersea cable?

In doing more research it looks like the WRT54G did not perform more than a few kilobytes per second. Some routers were provided by Berkeley that had been modified to use TDMA.

I found the the code on Github from this team, but it is an abandoned project, and specifically says it doesn't work.

Nothing has been setup on either side. It seems that Ubiquity gear utilizes TDMA, so I will see if I can get obtain it from Ebay.

I like your don't-wait-around-for-someone-else spirit. Get some more people involved too.

If there's signal in SJ then look into getting that. Put up a solar powered repeater drone.

I know nothing about PR. Do the cell towers use microwave or landline to long-haul? Seems like you first need to figure out what's available then find out a way to get something working.

Maybe now's a good time to get some competition going. Write letters to competing infrastructure companies to let them know markets exist that they may not have considered.

@fargenable How much money are you willing/able to spend?
"As little as possible" is not a valid answer. You certainly have a limit where you say "ouch, that hurts". Let us know that limit.

Regarding solar power: What solar panel + battery can you get? I guess with infrastructure broken down it might not be easy to get what you need.

As a rough estimate: 100Wp solar panel + 100Ah batteries per router, if you want 24/7 operation.

As a RF and comms savvy guy, and Ham operator, I could help you some I think.

First off, don't know what's up with that path calculator you used. It seems too optmistic and forgets to include curvature of the earth? This one gives a more expected answer, but if only 300 ft and 200ft on each side, your looking at 21 miles unobstructed.

Edit: I'm sorry I was so quick to disparage the Heywhatsthat path profiler, very good tool. But, you picked "flat earth" instead of include curvature.

Now, that's not to say you can get farther due to diffraction, or atmospheric ducting, but you'd be at the mercy of changing conditions. Are there any mountains near the prospective link areas?

Edit: I see islands inbetween, how high do they get at their peaks? Unless you have 3000-4000' mountains at the shores of PR and DR, you aren't going to make it in one hop. Multiple hops may be your only choice.

Basically, you need high locatons that would provide you with line of sight, good high gain directional antennas like dishes or many element yagis, and probably radios that have a fair amount of power. Though you can cross 60-100mi with a watt or less, especially with good antennas helping.

Being legal with this could be a challenge. You'd want to talk with officials on what you could do on which bands. Maybe get an emergency waiver from both governments?

You might want to look at what these guys are doing. You'll have to dig around a bit, dig up a powerpoint or video maybe, but the info is in there on off the shelf router and other radio link hardware with good dish antennas for long links. https://www.aredn.org/ They are creating high speed mesh network links out of off the shelf hardware. Interestingly, they based their firmware off OpenWRT...

They are designed to be a Amateur Radio (Ham) setup, using Ham frequencies. You would need to be licenced, and would be limited in what you could send. You may be able to use the radios on public frequencies, with power restrictions, and not be as limited. Also, possibly an emergency exemption from the gov's might be available.
Let me know what questions you might have.. would love to help over there...

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In theory, it could work. Take a Ubiquiti Litebeam, Nanobeam (5 GHz) etc and mount the feed part in a 2 meter C band TV dish. This should be better than 30 dB antenna gain. Take dish up to the hills and aim horizontally.

This path calculator predicts a potentially very usable received signal.

On a point to point link, regular wifi will work. The TDMA schemes are primarily to improve performance of a WISP system with multiple users.

The Nanobeam and probably the others, though rated for 24 volts, can be run on 12 volts from a very simple solar power system.

The main problem I see is that big dishes and solar panels are vulnerable to wind damage. Making a fixed installation robust enough to survive the next hurricane would be difficult. You would need to stash equipment and have it ready for rapid deployment after the storm.

Regarding some competition, I read that google is investing in comm infrastructure in PR. Of course that may take a long time but might be good to have some competition. i.e. lower prices

Yes, but.... if you were in space, no problem. If the Earth was flat, no problem. Otherwise, you are limited by line of sight, due to the pesky curvature of the planet. You will have a radius of horizon that will be determined by how high both antennas are.

There are some high mountains in DR, medium high on PR, but they aren't very close to each other. I haven't fully researched this, not sure if you could do a single hop. There is Isla de Mona half way between, that makes it easier. But, it seems it would be a major challenge to install a two way link there. Would have to be solar powered, besides the terrain....

Just noticed this thread. Any updates on what has been tried?

My 2c thinking about it is that it's probably easier to bring signals multi-hop from some center like San Juan across the island than trying to get a signal from Dominican Republic.

Also I'm thinking humidity is probably an issue. I definitely notice that the wifi background in my area disappears when we have fog... both 2.4Gig and 5Gig band seem to be attenuated heavily by moisture in the air, figure this means either very high power or much shorter distances than in dry environments.

Yes... the 2.4Ghz Wi-Fi band is unfortunately near the "microwave oven frequency" i.e. water absorption peak, so a lot of it along the path will cost signal strength. Im not as sure if 5Ghz is better or not. Higher gain antennas and more power can make make some of that up, as well as shorter hops. But, shorter hops mean more sites...

It's tough any way you try I guess.. be it a pair of long hops via an uninhabited and rough island (Mona) or several across hilly/mountanous and very broken up PR. Either way, lots of challenges installing, powering and maintaining remote sites in rough conditions.

I hope the short term and long term solutions for getting cell and net access to people out there are getting started and going well... wish I could help with that somehow...

Earlier I suggested solar powered repeater drones, little did I know that there were plans to do something like that with balloon equipped networking equipment. I don't recall what they were going to deploy. APs? or Repeaters? or some hybrid? or ???

Now would be a good time to lay fiber and turn the island toward modern infrastructure. Sort of a testbed for autodrones, high speed networks, wind, solar and hydro power. i.e. toward self-sufficient.

Apologies for finding this thread late. Unfortunately, it seems still relevant.

You may find the free book http://wndw.net/ useful as it covers a lot: antennas, power, management, ...

VHF should go that distance much easier than microwave
Suggest multiple 900MHz band old school HAM data links, running ML-PPP bonded at both ends. Like broadband cup-and-string?

Was there any progress in setting up long range wifi links for Puerto Rico?

I suspect by now that "standard" telecom is on the island, so at least a cross-ocean link isn't really an urgent necessity. Long distance links between towns might still be an issue. I read somewhere that "10% of cell towers are still out of commission" in about mid Feb, if that was accurate it means 90% of cell towers are working.

I think a bigger issue is still simply electrical power, and the fact that something like 10% of Puerto Rico abandoned the island for the mainland in the last 6 months.