Point To Point Solution

[Theo Van Wyk]

Hi

I am busy compiling a point to point solution for a customer and need some verification on equipment and calculations and the variables missed.

The distance is 200m from each other, attached is a picture the building where the connection will terminate. The other building is 50m behind where the picture was taken, not the most ideal position.

Equimpent

2 x AIR-CAP2602E-x-K9 mounted indoors

2 x AIR-ANT2566P4W-R= pole mounted if possible

2 x LMR400 6m

Free space path loss

L=32.5+20Log(f[MHZ]+(20logd[km])

=92.67

Fresnel Zone

r = 17.31 * sqrt((d1*d2)/(f*d))

2400 = 2.2m

5100 =1.5 m

So if you have a signal loss of -72.6dBi over the distance of 200m, and your transmitter has a maximum output of 20dBm

So if we pick a spot at that 200m mark what is our actual signal strength

EIRP - Path Loss = Signal

20 – 92.6 = -72.6  (Negative -72.6 ) which will fall into MCS21 MCS22 150 to 300 Mbps

The AIR-CAP2602E-x-K9  (2.4 GHz and 5 GHz): Receive Sensitivity

• 802.11g (non HT20) • -80 dBm @ 48 Mb/s • -78 dBm @ 54 Mb/s

• 802.11a (non HT20) • -81 dBm @ 48 Mb/s • -79 dBm @ 54 Mb/s

2.4-GHz • 802.11n (HT20) • -78 dBm @ MCS6 • -75 dBm @ MCS7 • -82 dBm @ MCS12 • -78 dBm @ MCS13 • -77 dBm @ MCS14 • -75 dBm @ MCS15 • -84 dBm @ MCS19 • -81 dBm @ MCS20 • -76 dBm @ MCS21 • -75 dBm @ MCS22 • -74 dBm @ MCS23

5-GHz • 802.11n (HT20) • -84 dBm @ MCS4 • -80 dBm @ MCS5 • -78 dBm @ MCS6 • -75 dBm @ MCS7 • -85 dBm @ MCS11 • -81 dBm @ MCS12 • -77 dBm @ MCS13 • -76 dBm @ MCS14 • -74 dBm @ MCS15 • -83 dBm @ MCS19 • -80 dBm @ MCS20 • -75 dBm @ MCS21 • -74 dBm @ MCS22 • -73 dBm @ MCS23

5-GHz • 802.11n (HT40) • -84 dBm @ MCS3 • -81 dBm @ MCS4 • -76 dBm @ MCS5 • -74 dBm @ MCS6 • -73 dBm @ MCS7 • -85 dBm @ MCS10 • -81 dBm @ MCS11 • -78 dBm @ MCS12 • -74 dBm @ MCS13 • -72 dBm @ MCS14 • -71 dBm @ MCS15 • -83 dBm @ MCS18 • -79 dBm @ MCS19 • -76 dBm @ MCS20 • -72 dBm @ MCS21 • -70 dBm @ MCS22 • -69 dBm @ MCS23

thank you anyone for helping

[Scott Fella · Accepted solution]

With one picture, its kind of hard to tell you, but you do must make sure its line of site, no tree branches in the way.  Also when you calculate EIRP, you need to also add the antenna dbi, subtract the cable loss, subtract the loss from each connector and the lightning arrestor.  That will give you your EIRP.  You will not know what your true signal is until the link is actually up, but your on the right path.

Cable loss can be calculated here:

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

Thanks,

Scott

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[Theo Van Wyk]

Thank you Scott, i was looking at the maximum EIRP for point to point link 2.4 GHz 20dBm and 23 dBm for 5 GHz  in the ETSI so my calculation was based on that if this is correct ?

Tried to keep it as close as possible to the max level

AIR-CAP2602E-x-K9 max output 22dbm

Antenna gain +6 dBi

Cable loss i took as -3

thank you for the Cable loss link :-)

[Scott Fella · Accepted solution]

Just remember that each connector subtracts 0.2 dbi and lightning arresters are 0.5 dbi. Since you are going to be placing the antenna outside, it's good practice to use a lightning arrestor. This would mean you would need 4 per AP if using all 4 antenna leads.

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[grabonlee]

Hi

From the picture, it seems it's an industrial area. I would not agree with you using the 2602, except it's encased. Why don't you use the new Cisco bridge product. I think it's 1502 or so.


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[Scott Fella]

Osita,

I beleive they were going to put the autonomous AP inside and run LMR cable to an antenna mounted outside.  The Cisco bridge they resell is the Exalt r5005.

Thanks,

Scott

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[Theo Van Wyk]

its all about the costs

[grabonlee]

Hi

Even if it's inside, as long as it's industrial, it's better to be in an enclosure. Also Cisco does have a point to point bridge that was released in Q2 of this year that replaced the 1300 and 1400. I'm not referring to the mesh AP. ,Check the Cisco site. Exalt isn't sold through Cisco but was recommended by Cisco after the end of sale of their old bridges.


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