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Access Point selection

Posted on 2008-10-04
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Last Modified: 2013-11-09
I am creating a small,  yet true and fully functional (as in assignment of external IP's in a class C block), highspeed WISP for a condo community which will serve roughly 100-150 residences and we would like to do it completely wirelessly.  Aside from the Indoor Cisco 1252, are there any other AP's that transmit IAW 802.11n?  The best solution would be outdoor 802.11n AP's because the tenants actually own the inside of the units and there are no hallways or HOA owned property connecting the inside of the units.  If there are no outdoor varients, could an indoor AP be used outdoors effectively (specifically the Cisco 1252 or some variant)?  Also, if not 802.11n, what are some options for highspeed 802.11x variants with low latency?  Finally, aside from WDS and a mesh, are there any other setups that will allow dynamic routing across the AP's?  IE, if the user wants to walk somewhere on the property and roam between the AP's without losing connection.  I've read that mesh and WDS kill the effective bandwidth--presumably due to the hops to get back to the base.

Note: the core setup for the WISP are two DS3's at 25/mbits with BGP redundancy, a cisco 7200 mxr router, and RADIUS server for authentication.

Very Respectfully,
Phillip
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Question by:veloxLLC
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by:Darr247
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The Cisco Aironet 1510AG is outdoor rated and dual band... in mesh mode they use the 5GHz radio to communicate with other 1510's, and the 2.4GHz radio for client connections, providing maximum bandwidth.
http://www.cisco.com/en/US/prod/collateral/wireless/ps5679/ps6548/product_data_sheet0900aecd803642e6.html is the info page for them... as it shows, AIR-LAP1510AG-A-K9 is the FCC-configured model, and they have many antenna and mounting options listed there as well.

*Probably* those will be upgradable to 802.11n when that standard is ratified, but that's still over a year away.
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by:veloxLLC
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As far as using the Cisco 1252 outdoors, is there a viable solution for that?  

Also, as stated before "Finally, aside from WDS and a mesh, are there any other setups that will allow dynamic routing across the AP's?  IE, if the user wants to walk somewhere on the property and roam between the AP's without losing connection.  I've read that mesh and WDS kill the effective bandwidth--presumably due to the hops to get back to the base."

Is there much of a degredation in perceived speed when using a mesh like there is in WDS?
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by:veloxLLC
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Also, as far as the .11g is concerned, how are some radios achieving a theoretical max of 108mbps?
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Darr247 earned 500 total points
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> As far as using the Cisco 1252 outdoors, is there a viable solution for that?  

It usually costs more to buy a NEMA-4x enclosure for a device than it does to buy the device in its weatherproofed version.


> I've read that mesh and WDS kill the effective bandwidth--presumably due to the hops to get back to the base."

As I said, the 1510's prevent the bandwidth loss you describe by using the 5GHz radios to talk to each other and 2.4GHz radios to talk to the clients.


> Is there much of a degredation in perceived speed when using a mesh like there is in WDS?

If done correctly there is no loss of speed when using a WDS Bridge. The reason ''repeaters'' cut bandwidth is because they have to spend half their time talking to the other bridge and half the time talking to the client-side... but if the WDS Bridge is connected 'back-to-back' with another AP, that eliminates the repeater step (rather like the Cisco AP's do by using one radio as the bridge and the other radio as the AP).  I've seen some people say each hop cuts bandwidth in half AGAIN, but that's not quite correct as I see it - each hop is running at half its maximum throughput, but once each hop is done transferring its data it's removed from the 'equation'.
Most setups don't have multiple T3's as you describe, either (each T3/DS3 should give about 45Mbps, btw... you might want to double-check with your provider what it is you're actually getting), but even halved by repeaters/bridges and then split by multiple users, few people ever experience a connection that fast. Even a true 10Mbps web connection is rare; cable connections typically top out at 6Mbps; a T1 line is just under 1.5Mbps, of course, and is plenty fast for streaming video.


> Also, as far as the .11g is concerned, how are some radios achieving a theoretical max of 108mbps?

Well, Frame Bursting works with any chipset, but both sides need to have it enabled (and it doesn't change the reported connection speed). That works by chaining packets together without adding headers to each packet, reducing overhead (not unlike Jumbo packets with gigabit ethernet, just not as big).
Atheros chipsets implement SuperG and Turbo, report 108Mbps connection speeds, and actually do double the maximum throughput to about 60Mbps.
Broadcom calls their technology 'Afterburner' and 'Turbo-G', and since Linksys uses Broadcom chipsets in most of their stuff, that is what's behind their 'Speedbooster' models.  'Turbo' does not equal 'Turbo-G', and neither of them talk any faster to the other chipset's radios (except in Frame Burst mode). And from the tests I've seen Atheros to Atheros is faster than Broadcom to Broadcom (and as far as I know there aren't any Broadcom-chipset MiniPCI cards, anyway).

IMHO, the Atheros Super-G is a 'good thing' for 11a, but not 11g. It uses the same technology 11n uses for higher speeds - a 40MHz-wide channel, which essentially overlaps 10 of the 11 channels available in the americas for 11b/g devices (e.g. channel 1 and 6 together would make a double-speed 40MHz-wide channel, leaving only channel 11 for nearby 11g devices to use interference-free). There are eight to twelve non-overlapping 20MHz-wide 11a channels available in the 5GHz band, meaning you could have four to six 40MHz-wide channels instead of just one, as the 2.4GHz band (having only three non-overlapping 20MHz-wide channels) has room for.
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by:veloxLLC
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the DS3's are a minimum commit of 25mbits, with a burstable speed of 45.  So basically we have the equiv of 1 full DS3 with redundancy.
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