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Long range 802.11n equipment

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  • 08-08-2009 6:51pm
    #1
    Señor Juárez
    Closed Accounts Posts: 1,388 ✭✭✭


    Recently, myself and a few others have been experimenting with some 802.11n gear. We bought two of these yokes: http://site.microcom.us/awus050nh.pdf (Alfa AWUS050NH). They contain a Ralink RT2770F chipset.

    They're quite decent adaptors, supporting 802.11n in 5GHz mode. We also acquired two 28dbi antennas for our experiments.

    We attempted a link between Bray head and Howth head (20km). It sort of worked - despite 99% signal strength and a rock solid connection, we were not able to get any data through them. It seems that the MAC implementation timings for 802.11n are quite sensitive - in the order of microseconds. The extra time taken for the radio waves to propagate along 20km causes everything to time out, hence no real data through. More info about this at http://www.air-stream.org.au/ACK_Timeouts .

    So my question is, does anybody know if it is possible to modify the timeouts on these cards in any way, on any OS? Are there any alternative drivers I could use to enable this?

    Alternatively, is anyone aware of any other hardware they could recommend? It is very difficult to find any equipment which is suitable as the following are absolutely essential:

    802.11n support in 5GHz mode (most adaptors which are 802.11n only work in 2.4GHz mode)
    An external antenna connector
    Reasonable pricing!

    Any advice or input appreciated.


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    #2
    Some_Person
    Closed Accounts Posts: 491 ✭✭Some_Person


    I've also been doing alot of research myself lately for a multi km link on 5Ghz although only for 8km. I wouldn't favor USB adapters for that task. Ubiquiti have the Bullet 5 and are just after releasing the new BulletM5HP which supports 802.11N on 5Ghz with allegedly 100mbits of tcp throughput. Their OS (AirOS) has ACK options including AutoAck although some reccomend not using AutoAck and setting Ack to 10% greater than the actual distance.You can change the output power channel width and rate algorithm etc.

    Also be aware that the regulatory limit for 5Ghz here is 2Watts EIRP, so to keep just within the limit you'd have to limit the Bullet's output power to 5 dbm when using 28dbi antennas(which I hope are grids?).


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    #3
    Señor Juárez
    Closed Accounts Posts: 1,388 ✭✭✭Señor Juárez


    We did a good bit of research but unfortunately didn't come across those :(

    http://www.wi-pipe.com/bullet5-p-342.html?antenna=c0b52f80f5419b49ef073b371de1bd42 wi-pipe sell them too, excellent. And they're really damn cheap! The power situation is quite vague, though. It doesn't specify if it comes with built in PoE, or if there is even a power supply with it at all...


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    #4
    Some_Person
    Closed Accounts Posts: 491 ✭✭Some_Person


    Wi-Pipe have the Bullet5 which is 802.11A only, they don't have the BulletM5HP which is 802.11a and 802.11n. Aerial.net are supposed to get them in a few days. Landatel also have tons of gear but I'm not sure if they are only wholesale. They have a PoE connection but don't come with PoE adapters for some reason so you'll have to get one from the shop, make sure it's no stronger than 24volt or it will fry the Bullet, the supplier should know.


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