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New Member

Outdoor 5ghz MIMO deployment.

Hello..

We are interested in adding 5ghz N MIMO to our existing outdoor wifi 2.4ghz hotspots. Currently we have 3 x 1310 ap's with MSO24014 all-terrain antennas (seen in the attached photo) atop 19 foot towers..

I'm looking at either 3 x 1532E AP's paired with 8 dBi AIR-ANT2588P3M-N antennas or 3 x 2603 paired with the 6dBi AIR-ANT2566P4W-R antennas.

Here are my questions:

The 1532E has a 27dbi (500mw) tx power, while the 2603 has only a 23 dbi (200mw) tx power.. Both are obviously better that the 1310's 20dbi (100mw) tx power. But how much is too much? It seems like these 1532e's at full tx paired with the 8 dbi 2588P3M antenna might push the signal too far for mobile devices to respond.

I'm curious how an omni 5 dbi cisco antenna would perform on these towers if mounted on the metal tower structure. Would it be a waist of time due to the obvious reflection pattern the towers would cause?

I was thinking about placing the antennas around the 17 foot mark..

My goal is to bring pure 5ghz N MIMIO to the existing towers while leaving the 2.4gh alone. Bringing cell coverage in for a good quality coverage but not too close since this is an RV park.

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Hall of Fame Super Gold

Outdoor 5ghz MIMO deployment.

I'm curious how an omni 5 dbi cisco antenna would perform on these towers if mounted on the metal tower structure. Would it be a waist of time due to the obvious reflection pattern the towers would cause?

The antenna you will be using are directional patch antenna.  So the "reflection" from the tower is very neglibable. 

I was thinking about placing the antennas around the 17 foot mark.

You will need to tilt the patch antenna down to some degrees to the ground. 

The issue you've got is that these RV's roof are made out of metal.  Unless they have an external antenna sticking out, the signal, or some of it is going to be bouncing off the roof. 

But how much is too much? It seems like these 1532e's at full tx paired with the 8 dbi 2588P3M antenna might push the signal too far for mobile devices to respond

Your assumption is correct.  Too much power does not guarantee that the antenna could pick up the response from clients.  Another thing, how do you plan to deploy the AP and the antenna.  The longer the co-ax cable between the AP and the antenna the higher the signal loss is going to be. 

10 REPLIES
Hall of Fame Super Gold

Outdoor 5ghz MIMO deployment.

I'm curious how an omni 5 dbi cisco antenna would perform on these towers if mounted on the metal tower structure. Would it be a waist of time due to the obvious reflection pattern the towers would cause?

The antenna you will be using are directional patch antenna.  So the "reflection" from the tower is very neglibable. 

I was thinking about placing the antennas around the 17 foot mark.

You will need to tilt the patch antenna down to some degrees to the ground. 

The issue you've got is that these RV's roof are made out of metal.  Unless they have an external antenna sticking out, the signal, or some of it is going to be bouncing off the roof. 

But how much is too much? It seems like these 1532e's at full tx paired with the 8 dbi 2588P3M antenna might push the signal too far for mobile devices to respond

Your assumption is correct.  Too much power does not guarantee that the antenna could pick up the response from clients.  Another thing, how do you plan to deploy the AP and the antenna.  The longer the co-ax cable between the AP and the antenna the higher the signal loss is going to be. 

New Member

Outdoor 5ghz MIMO deployment.

The antenna you will be using are directional patch antenna.  So the "reflection" from the tower is very neglibable.

Right, but I were to deply a mixture of omni and patch at each location for coverage, what kind of interference could I expect if we were to mount the dome style 6 inches out from the aluminum structure? Loaded question, I know.. Would the omni / dirrectional ultimitly cover "about" the same area anyway due to interference?

Your assumption is correct.  Too much power does not guarantee that the antenna could pick up the response from clients.  Another thing, how do you plan to deploy the AP and the antenna.  The longer the co-ax cable between the AP and the antenna the higher the signal loss is going to be. 

We are using the structure in the picture to house all of the equipment (isp, cisco router, ap's and batery backup). From the AP we are using 25 foot high quality sheilded coax upto the antenna's..My biggest concern is over powering the wifi cell..

Hall of Fame Super Gold

Outdoor 5ghz MIMO deployment.

My recommendation is to start from the middle of the park and slowly roll out your wifi outward until you hit your boundary. 

Hall of Fame Super Gold

Outdoor 5ghz MIMO deployment.

Right, but I were to deply a mixture of omni and patch at each location for coverage, what kind of interference could I expect if we were to mount the dome style 6 inches out from the aluminum structure? Loaded question, I know.. Would the omni / dirrectional ultimitly cover "about" the same area anyway due to interference?

It's loaded. 

Here's your dilema:  Ok, so if you use omni antennas on top of a 17-foot tower, you won't get signal if the tower is between the antenna and the client ... say, you'll get 270-degrees of coverage.  Next, height.  Your signal will go straight ... 17-feet of dead space.  Sure signal will go down too (depending on the footprint of the antenna).  But I still say this is too high. 

From the AP we are using 25 foot high quality sheilded coax upto the antenna's

Wow.  That's a long cable.  Don't know what the signal loss is going to be but I'm sure it's going to be very significant.

Hall of Fame Super Silver

Re: Outdoor 5ghz MIMO deployment.

Leo,

Depends on type of cable. 25' using LMR400 not much. LMR600 very little. I use this calc when I have an outdoor wireless project.

http://timesmicrowave.com/calculator/?productId=52#form

Sent from Cisco Technical Support iPhone App

-Scott
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New Member

Re: Outdoor 5ghz MIMO deployment.

I'm not sure what kind of cables we use, they are specially made and shipped to us.. I'll look into that.

how can I estamate coverage distace with these 1532E AP's paired with the 8 dBi AIR-ANT2588P3M-N?

Hall of Fame Super Silver

Re: Outdoor 5ghz MIMO deployment.

You need to use a tool to validate coverage. That is the only true way to know your coverage area.

Sent from Cisco Technical Support iPhone App

-Scott
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New Member

Re: Outdoor 5ghz MIMO deployment.

Thanks for all of your assistance..

I'm having trouble finding a strait forward webiste for calculating distance, but I have been able to figure out the formula from these forums..

The Cisco 1532E ap has a tx power of 27dbi. We're using 2 x 25 foot CFD-400 cables (.35dbi loss per meter). Combined with Cisco's 8 dBi AIR-ANT2588P3M-N. 

EIRP = Device TX Power - Cable Loss + Antenna Gain

  • That gives me 27dbi - 2dbi + 8dbi = 33dbi
  • (do I need to add both cable -dbi loss into the above equation)

Free Space Loss =(20*LOG10(D5*1609.344))+(20*LOG10(D9))-27.55

  • I have the MCS -dbm chart for the AP but I'm not sure how to put that together with a typical Laptop / iPad device.
  • Is 25mw with 0 - 2di antenna still pretty average for Laptops and iPads?

Thanks for your help

Hall of Fame Super Silver

Re: Outdoor 5ghz MIMO deployment.

What you need to add to the cable loss is also the number of connectors and lightning arresters. These will also affect your total EIRP.

Sent from Cisco Technical Support iPhone App

-Scott
*** Please rate helpful posts ***
Hall of Fame Super Silver

Re: Outdoor 5ghz MIMO deployment.

You can look at this link also to help with some calculations

http://www.radiolabs.com/stations/wifi_calc.html

Sent from Cisco Technical Support iPhone App

-Scott
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