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  #1 (permalink)  
Old 02-11-2018, 5:06 PM
   
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Default LAN over a few miles for Public Safety. How to and what frequencies?

Not sure if this is the right place to post this but here we go:

Long story short:
I am looking to make a network over about a 2-3mile range around my fire department. We would like to be able to have Wifi in the trucks that will communicate back to the station to access files on the station's server, and also ideally use the stations internet so that we can have internet anywhere in the district. The point is to not use the cell network both in case it goes down, and to avoid the use of data plans.

I took note of the 4.9GHz public safety spectrum but it looks like there are not many manufacturers of equipment for that specific use. I am wondering if there is anything in the 700Mhz or 900Mhz region. Not looking for huge data rates; in fact just a few Mbps is good.

The station has a 40ft tower, and the station itself is located at a reasonable elevation. Looking to serve a 2-3 miles radius that is mostly rural but there is a shopping center area in the district.

I understand FCC licensing and radio propagation when it comes to voice (Analog, DMR) but not so much when it comes to data.

So is this just a fantasy or is there something feasible out there?
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Old 02-11-2018, 6:44 PM
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Quote:
Originally Posted by jonnyblanch View Post
So is this just a fantasy or is there something feasible out there?
No, not a fantasy, lots of agencies have systems like this.

A mesh network is what you need, however it's going to require access points scattered every few blocks to work well.

There are a lot of good point to point systems out there. But what you are looking for is more of a wide area wireless network.
Yes, it can be done, but not easily or cheaply. Standard LMR, 700 and 900MHz, as you suggested, isn't going to have enough bandwidth to get you "a few MBPS". There are 700MHz channels assigned for data communications, but that's going to be slow speed stuff, like on the order of a few kbps, less than modem speed. Not suitable for file transfers.
Same on 900MHz. You are not going to get anything with enough bandwidth.

This is why so many agencies are using cellular. It's cheaper than building out a large network on your own. It's also a lot more flexible.
Now that FirstNet is coming along, it even makes more sense. Your fire department would qualify to use FirstNet, and it's going to be designed for exactly what you are looking for.

If building your own is really what you want to do, it's likely going to need to be a WiFi based system with enough nodes to give you the coverage you need. Again, it can be done, but initial costs, upkeep, etc. is going to add up, and if you only have a few trucks to do, cellular/FirstNet is going to be cheaper.
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Old 02-11-2018, 7:02 PM
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In the long run you may be better off to just call AT&T and get on First Net. I believe it's like $50/month/device for unlimited data. They will have hot spots you can put in the truck and then have everyone on wi-fi. They also for additional money connect you directly to your IP network .Best bet would be to pair up with other agencies in same city or county and share the dedicated connection to your county's IP network. Maybe just start a push for every one to get on First Net.
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Old 02-11-2018, 8:38 PM
   
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Quote:
Originally Posted by bchappuie View Post
In the long run you may be better off to just call AT&T and get on First Net. I believe it's like $50/month/device for unlimited data.
Not sure what the status is of First Net in our area. Also, $50/month/device is pretty steep considering we will hardly use any data under normal circumstances. I'll do some more digging on First Net in my area.

Thanks!
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Old 02-11-2018, 8:57 PM
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Quote:
Originally Posted by mmckenna View Post
No, not a fantasy, lots of agencies have systems like this.

A mesh network is what you need, however it's going to require access points scattered every few blocks to work well.

There are a lot of good point to point systems out there. But what you are looking for is more of a wide area wireless network.
Yes, it can be done, but not easily or cheaply. Standard LMR, 700 and 900MHz, as you suggested, isn't going to have enough bandwidth to get you "a few MBPS". There are 700MHz channels assigned for data communications, but that's going to be slow speed stuff, like on the order of a few kbps, less than modem speed. Not suitable for file transfers.
Same on 900MHz. You are not going to get anything with enough bandwidth.

This is why so many agencies are using cellular. It's cheaper than building out a large network on your own. It's also a lot more flexible.
Now that FirstNet is coming along, it even makes more sense. Your fire department would qualify to use FirstNet, and it's going to be designed for exactly what you are looking for.

If building your own is really what you want to do, it's likely going to need to be a WiFi based system with enough nodes to give you the coverage you need. Again, it can be done, but initial costs, upkeep, etc. is going to add up, and if you only have a few trucks to do, cellular/FirstNet is going to be cheaper.
I wouldn't do a MESH but that's just me. I'd go with an OSPF ring with APs in order to keep latency and cost down. Something like Mimosa A5's running on 4.9 GHz backhauled by IgniteNet 60 GHz PtP links. Even doing that though you are still looking at a 3 port router, PoE injectors and the radios ($400 for the 60 GHz radio, $900 for the A5). Not having a central controller are where 4.9 will get you though.

In the oilfield we used to use the GE iNET and iNET-II radios. They'd only provide 1 Mbps of throughput but operated in the 900 MHz ISM band at 1W. Don't know if that would meet data needs. Also, one could check out MobileIP Net from RF Technology or similar offerings from other vendors to provide narrowband IP data but it is slow (256 kbps or less) by our standards.
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Old 02-12-2018, 7:28 PM
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If it’s not mission critical, you could also look at MVNOs who resell larger companies mobile services cheaper. The one I use uses both sprint and at&t networks and it works ok for me.
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Old 02-12-2018, 8:54 PM
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You might also try and find out what solution your local (or county, or state) law enforcement are using for their mobile data terminals. If they're not on 4G wireless, they may already have a WiFi-like, or -based solution your apparatus can piggyback on. Even if it's not a WiFi solution, a 4G hot spot on each truck may be within the realm of possibility.
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Old 02-17-2018, 7:30 AM
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Look at Data Radio. Our county utilizes this for our MDT system. Its not super fast but is on 800Mhz and allows us to access CAD. I looked into these boxes for SAR at one point and the ones we had did 9600. Wasn't rocket fast but i could access files on my server. I think the new ones do allow for more speed on 700 mhz.
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Old 02-17-2018, 8:30 AM
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If $50 a month per device for a couple devices is too much there is no way you are going to be able to afford deploying your own proper system.
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Old 02-17-2018, 8:41 AM
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With your push back on price, I guess the wireless device Verizon has at around $60 a month won't fit your needs either. It uses a USB connection for power. It provides a wireless connection like WIFI for your computer to use and runs off the cellular system.

The unit is about the size of a pack of cigarettes, but is only about 1/4 inch thick. Have used one for many years now and found very few places I go around the country that I didn't have service. We call them hockey pucks, but forget the real name.

The speed is good and reliable. It is also secure, so you don't have to worry about someone getting into it and using your connection. It will support multiple users at the same time.
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Old Today, 2:45 AM
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I think VZW calls them mifis, I have 2 and neither works well in Texas for some reason.

The signal never drops, I just lose IP connectivity. If I stream a radio station the link works but trying to web surf or read email on the 2nd unit on a 2nd PC will drop off after 20 min or so.
I talked to a guy who said he switched to AT+T because of the same reason.
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Old Today, 8:50 AM
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Take a look at the Cisco 819. Provides a cellular interface, 4 fast ethernet ports and 1 gigabit port.

You can pick them up from eBay extremely cheap.
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Old Today, 8:53 AM
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Quote:
Originally Posted by speedway_navigator View Post
I think VZW calls them mifis, I have 2 and neither works well in Texas for some reason.

The signal never drops, I just lose IP connectivity. If I stream a radio station the link works but trying to web surf or read email on the 2nd unit on a 2nd PC will drop off after 20 min or so.
I talked to a guy who said he switched to AT+T because of the same reason.
Verizon is just about the only thing that works in the Permian Basin.
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Old Today, 10:02 AM
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Ubiquiti sells mesh network wireless for 5.8, 2.4, and 900 mhz
all license free.
And they are cheap and reliable.
......
But one access point at the station on 2.4ghz may get the job done
and if you don't use 800mhz radios in the trucks, you could use 900 mhz.
........
Naturally 900 mhz tends to cover better especially in non line of sight
areas.
.....
But with a mesh network, you can have multiple APs spread around
like cell sites so the coverage would be greatly improved
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