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New Member

Number of 5-GHz, 14-dBi Directional Antennas on a singe AP1552EU

HI,

     Currently desiging a Mesh Network to cover a large area and i am working with the AP1552EU AP that has 3x 2.4GHz antenna Slots and 3x 5GHz antenna slots. I will be using the 5 GHz for backhauling, but would like to know how many 14-dBi Directional Antennas two ports, N connectors (AIR-ANT5114P2M-N=) can be deployed be PA 1552 EU Access point. I ask this becuase since this is a directional antenna i would like to know if i can use one antnna for the upsteam AP in the Mesh and another antenna for the downstream AP in the Mesh.

Regards,

Raed

  • Getting Started with Wireless
8 REPLIES
New Member

Number of 5-GHz, 14-dBi Directional Antennas on a singe AP1552EU

That is not possible. 1552s have one radio with three antennas. Ie all three antennas are/may be used for to transmit the same message at the same time. Think about this AP as having an antenna array for the same radio therefore there shall never be a system designed to cover different areas with different antennas connected to the same AP..

New Member

Number of 5-GHz, 14-dBi Directional Antennas on a singe AP1552EU

Hi vlad,

    The AP i am using is the AP1552EU not the AP1552s.

http://www.cisco.com/c/en/us/products/collateral/wireless/aironet-1550-series/data_sheet_c78-641373.html

as per the data Sheet it has 3x 2.4GHz antenna Slots and 3x 5GHz antenna slots, unless i am missing an EOS notice.

regards,

Raed

New Member

Number of 5-GHz, 14-dBi Directional Antennas on a singe AP1552EU

Raed,

I didn't mean 1552S AP, all 1552s have one radio for 2.4GHz and one radio for 5GHz (all - 1552H, 1552E, 1552EU etc).. The three antennas for the 'EU' model are single band. The 3 antenna connectors for 5GHz are wired in to a single 5GHz radio. One, two or three antennas (radiating elements) in this case will form and be operated by the 1552 5GHz radio as a single antenna array (and not as independent antennas). That array has to be 'directed' to cover the same area. You should never-ever design this antenna array in such way that has one antenna point in one direction and another antenna point in to different direction (ie one antenna cover one area and another antenna cover different area).

New Member

Number of 5-GHz, 14-dBi Directional Antennas on a singe AP1552EU

vlad,

     I really appreciate your support, thank you for your clear explanation. May i ask if can i use 3x 8 dbi antennas to create a backhaul between 2x mesh access points 400 meters apart?  Or is 200m the maximum i can achieve. Because frankly i am trying to design with 4 hops and what to know what is the maximum backhaul distance with the 5ghz antennas while at the same time have full 2.4 Ghz coverage between the APs.

Regards,

Raed

New Member

Re: Number of 5-GHz, 14-dBi Directional Antennas on a singe AP15

Scott has provided a link to the 1552-series distance calculator. Its a great resource to use for designing for 1552-series. 400 meters is not that long of a distance for this AP using omni directional antennas, although it also depends on the regulatory domain you are in.

The 4-hop design will lead to decreased throughput. Keep in mind every hop will bring your available throughput approximately in half :-(

New Member

Re: Number of 5-GHz, 14-dBi Directional Antennas on a singe AP15

Dear Vlad,

    

          I thank you for your support. you have mentioned that every hop will half the availble througput, for example RAP will have X mbps, MAP A1 will have X/2 and MAP A2 will have X/4 mbps (RAP ---> MAP A1 ----> MAP A2). Is halfing the bandwidth also apply when i dint have multiple hops but more access points on the RAP (MAP A1 <---- RAP ----> MAP B1) if i add a MAP C1 to the RAP will that divide the availble bandwidth by 3 (X/3) and then i have to divide that bandwith by 2 for every hop onwards or does each first MAP get the full Backhaul of the RAP as if there is only one MAP connected to the RAP.

BTW what is the Starting bandwith with the 1552EU AP it is 300 Mbps or 54 Mbps for the backhaul ?

(RAP: Root Access Point, MAP: Mesh Access Point)

Regards,

Raed

New Member

Re: Number of 5-GHz, 14-dBi Directional Antennas on a singe AP15

You are correct. When you have multiple MAPs connecting to a RAP they all share one channel thus your total througput is divided between all MAPs. Now the "halfening" effect is happening because you have the same radio receiving a packet from downstream MAP and transmitting the same packet to the upstream MAP. Since this is happening on the same channel all participating cells have to shutdown and listen while a packet gets retranslated (and I am not even mentioning the ack for each packet!)

In your question I believe you are using two words bandwidth and througput but they are different. We usually use Data Rate for the transmission speed per packet. That speed depends on a number of factors: noise, signal-to-noise ratio, amount of possible MIMO streams and other RF parameters. Data Rate dictates the maximum speed for your transmission. If you plug your numbers in the spreadsheet that Scott provided you will get your data rates.

Throughput is how much data you can actually push. It is common to anticipate a throughput to be about 1/2 of your data rate but that is only the begining. There is a need to factor retries, amount of clients/MAPs/hops your system has, RF colisions, retries etc etc. Solid estimates for throughput come out of a site survey. Actual numbers often are not available until after post-implementation survey.

Hall of Fame Super Silver

Re: Number of 5-GHz, 14-dBi Directional Antennas on a singe AP15

You can use this calculator to determine if you can or not.

https://www.cisco.com/en/US/docs/wireless/access_point/1550/range/calculator/1552_Link_Calculator_V1.xls

Sent from Cisco Technical Support iPhone App

Thanks, Scott *****Help out other by using the rating system and marking answered questions as "Answered"*****
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