View Full Version : Possible omni config for mimo
Headbang
08-21-2009, 07:08 AM
First of all, I'm in Canada.
Based on current usage the new products can get me 100-150 clients per tower. With this in mind, is there any reason one could not use 1-15db vert omni and 1-13db horiz omni connected to a rocket M? I would have to put one facing up, one down, and separate them by 2-6FT near as I can figure.
Secondly, if I filtered both would there be any issues?
Thirdly, if I put a diplexer with filter on the vertical omni and ran G on channel 1 and N on channel 11 (10Mhz G) this would support existing installs and allow me to offer new packages at higher price points.
Reason behind these questions is, MiMo should always offer better speeds and quality through tree's and buildings. This would allow us to blow away the canopy competition by offering double to triple, maybe even 4X the speeds they do. And not have as many interference issues by non-self sources.
Cost of this would be around $800 per existing tower. For my light towers I could remove existing sectors and add a dish with rocket for increased backhaul with no change in wind loading. Of course all new towers would be based on new tech only, while allowing me to max my investment on the 500+ pieces of LS2, NS2, PS2, and Bullet2's already existing. I could also increase height of antennas up to 20FT by using a 2" pole on top of the towers. I would gain 2db of cable loss and lose it again with the diplexer, so no loss on existing.
rconaway
08-21-2009, 09:56 AM
I'm interested to see what happens if you run 2 omni's on the rocket?
opampca
08-21-2009, 01:35 PM
Interesting, you can always ask John Chen from Superpass lo let you try his dual polarised omni model SPDPG-4O-H2O . Its gas 30db isolation, not a lot of gain (6db) and 24/30 deg vertical.
Could be worth a try.
http://www.superpass.com/SPDPG-4O-H2O.html
rconaway
08-21-2009, 03:58 PM
I was thinking 2 vertical antennas.
opampca
08-21-2009, 06:49 PM
Well regular 3x3 N on domestic routers use 3 vpol omnis...
I don't see why it wouldn't work well
You could use a Superpass omni VPOL and HPOL for polarization diversity, space them three feet apart.
Those three antennas on a MIMO router use spatial diversity, which is not very effective at longer distances. I explained the math in another post last year.
rconaway
08-22-2009, 06:18 AM
I can't find that post. Can I assume that the farther you are away, the timing differential gets smaller and you eventually lose enough timing differential as a percentage of the timing due to distance to have any value?
Headbang
08-23-2009, 07:24 AM
Reason for horizontal and vertical is to make compatible with NanoM.
Of course, if in real life the mimo side does not offer much advantages when trying to penetrate tree's over a 2-8 mile range, then there would be no reason to complicate the issue, a single 15db omni on a bulletM with a filter would be lower cost, less to deploy, and simpler for all sides.
A lot of testing is going to be necessary before any deployments are made for me. Launching a new 80FT tower with a 15db omni and bullet2m next week. Using bullet 5M's with grids for the backhaul. We will see how it performs with and without filters. If it works better then an XR2,XR5/RB433AH combo it will be worth retrofitting towers currently at capacity.
rconaway...
Rory, let me look for my calculations. I know that I discussed how antenna spacing diversity was ineffective at longer distances, but using polarization diversity would still be very effective.
rconaway
08-23-2009, 02:50 PM
What I'm actually looking for is the longest range for mobility and laptop users. If I turn off polling, and then use the Mimo function with Rockets on both sides using verticals (car for example), how does that compare to a bullet M to bullet M solution?
Wow....we were sitting on the back porch Friday night listening to the night critters and talking about vehicular radio.
We did the "what if" game. Given that a mobile transmitter (i.e anything that is not fixed such as an AP on a tower or CPE on a house), you are limited to 36 dBm EIRP and that an antenna over 6 dBi has too flat a pattern...
On the mobile side -
* Any radio would works at its highest TPO, as no radio has over 30 dBm TPO.
* An elevated feed would be desirable. Testing with a 3 dBi radome antenna last month showed significant shadowing from a police car's light bar.
* A 5 dBi elevated feed (no ground plane required) and magnetic mount worked very well.
* A single Bullet M would work, but we think a Rocket with two antennas spaced a few feet apart would be superior.
On the AP side -
* A Rocket with two vertical antenna spaced at least several feet apart might be as good as a vertical VPOL and HPOL combination. This was assuming a max AP to mobile distance of two miles.
rconaway
08-23-2009, 05:16 PM
The best you are going to do on the Police Car is about 4 feet apart across the trunk. That's what Tropos does. However, assuming the rocket 2M is 25dBi output, we are leaving a little on the table in the car, about 4dBi since the best antenna is going to be 7dBi. I think it's a good idea.
I was thinking on the roof. And yeah, I'd run the BM2 at max TPO.
28 dBm + 7 dBi = 36 dBm, oen dB under 36 dBm.
rconaway
08-23-2009, 06:34 PM
The problem with the BM2 is single antenna. It's what I'm going to run depending on the specs on Rocket 2. However, that is as close as we can get but it's still pretty good.
The next question is how well does the MIMO work in a moving vehicle with signal jumping around. Basically, does MIMO work in that environment as well as true diversity.
Well, obviously not as well as passive diversity where there is an antenna splitter. But good questions, just how fast can it switch over?
Sounds like someone needs to buy some Rockets and antennas, then spend the time to test that out.
rconaway
08-23-2009, 06:45 PM
When they are available, I will check it out. It will kick that crap out of Tropos if it works.
I can start up a city mobile video wifi in two weeks on 2.4 Gig, but I'm not even gonna consider it until Inscape Data comes out with a decent product.
Perhaps a mobile Meraki ??? :lol:
rconaway
08-23-2009, 06:59 PM
I'm beyond considering it. We are making arrangements to put a 4 square mile are in.
kc0eqf
10-05-2009, 12:53 PM
What is the name brand and model ot the omni that you prefer to use on your towers? thanks
Rory....What radios for the AP and ther mobiles?
