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New deployment by Border Patrol Tucson Sector

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New deployment by Border Patrol Tucson Sector


One of the BP agents here in Tucson is also a ham. He has gotten approval to deploy nodes on their tower that is around 100' high. Here is his questions.

The mesh network equipment installation for the USBP tower is finally getting closer.  The equipment on hand is:
3 - Ubiquiti AM-V2G-Ti 120 Degree Sector Antennas
3 - Ubiquiti Rocket M2 Radios
1 - Ubiquiti ToughSwitch PoE Pro Managed Ethernet Switch
Please get with your guys and figure out how they should be arranged on the tower for least interference between each other, and how the firmware should be configured on the radios themselves.  I can get the radios to you for configuration.  If a solution to configure the placement of the antennas to reduce interference between radios can not be had, maybe we can look at a different solution.  Regardless of that, the tower loading numbers are being run for three large sector antennas, so any other antenna solution will be of lesser loading and will still be able to be pushed through.

Thanks guys.

Bob, W7REJ

AE6XE's picture
There are a few other forum
There are a few other forum posts on this subject.   It would yield up to 3x the performance to put up 3 rockets using 3 different channels for the 360 deg coverage.  This usually can't be accomplished in 2Ghz without getting into area wifi noise trashing a couple of the channels.   Is the tower by chance out in a low density populated area or in Tuscon?   If it were me (and money fell from trees), I'd go get a 3Ghz and 5Ghz rocket-sector or 2 x 5Ghz rockets to deploy with 1 of the 2Ghz. 
RE: New deployment by Border Patrol Tucson Sector
Then how would individual users be able to use these nodes to tie into the mesh if 1) two of the nodes aron different channels and 2) two of the nodes are on 3GHz/5GHz. Makes no sense to me.

All we're trying to do is expand the mesh and give users in that area a way to tie into it. If need be we would do a point-to-point link to connect this area to a mesh network that serves another neighborhood. This other location is covered by a node up about 120' that is LOS to the BP Tower location. Isn't using (3) 2.4GHz nodes (dtd linked to each other), covering 360° the way to go? The location is SE Tucson located on the northern edge of Davis-Monthan AFB.

For my town of Sahuarita, we are going to place a node at about 80' using a rocket and mimo omni for local coverage then dtd connect that to a 3GHz node for a point to point link to another 3GHz node in downtown Tucson that will cover that area on 2.4GHz. This is a similar scenario to the BP tower location accept the BP tower location is planning to use 3 nodes for 360° coverage but no plans for a point-to-point link unless that becomes necessary.

Still the question if using this needs to be answered. How best to shield them from each other? I'll do a search on the forum to see whats what but posted this here since this is a deployment forum and this is a deployment question.

Bob, W7REJ

K5DLQ's picture
re: How best to shield them
re: How best to shield them from each other?

I think the recommendation is to NOT shield them since they are all on the same channel.  This way, they can do proper CSMA collision detection.  The downside is reduced throughput.

I think what Joe was trying to say is:
if you use 5Ghz band, each node is on a different channel (and shielded) which means low CSMA collision issues, and higher throughput.  Then, people in the "field" would also use 5Ghz radios/nodes.

K6AH's picture
Use of AM-V2G-Ti

I don't have any experience with the UBNT AM-V2G-Ti antennas.  They are certainly what Ubiquiti recommends as a hedge against collocated QRM.  I'll be interested in your performance report.  Joe and I have a fair bit of experience with collocated interference.  It's a tough issue to overcome, so I understand why he recommended cross band operation.

Andre, K6AH

AE6XE's picture


"how would individual users be able to use these nodes to tie into the mesh?".     This design of a different channel in each quadrant assumes the users are primarily fixed base users with settings for the respective quadrant.   The Tower site would have each of the mesh nodes DtDlink'd together so that data packets route at the tower from a user on 1 channel in a given quadrant to another channel in another quadrant.    Everyone is on the same mesh network regardless of what band or channel they connect in with.   3 channels in use means 3x bandwidth means 3x thoughput, if you have the luxury to do so.

To support mobile users in all 360 deg, I'd put up a rocket mimo-omni  and use a unique channel, but the gain will not be as high as the sector.   Providing 360 deg coverage with 3x the equipment is 3x the cost for marginal gain.    

I don't think it is feasible or practical, at typical tower sites, to install multiple devices on the same channel and be able to isolate such that they wouldn't have to coordinate sharing the frequency.  These devices are really good at decoding weak signals and a site that wouldn't have some energy bouncing off things everywhere in the environment would be almost impossible to avoid.


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