high throughput on access points

[suthomas1]

Hi,

AP's today support 802.11n ( upto 300Mbps ) throughput. Is there any specific configuration to enable 802.11n to be used as backend link for the 802.11a usual links.

or does the ap auto negotiates. What factors determine if the AP will use 802.11n as its backhaul link?

Thanks in advance!

[Scott Fella]

Link speed is determined by ap and client or ap and ap negotiating modulation. There are many things that can affect how two devices determine its modulation and this it's link speed.

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[Scott Fella]

Found a link that sort of explains what I'm trying to say:)

http://compnetworking.about.com/od/wirelessfaqs/f/dynamicscaling.htm

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[suthomas1]

Thanks.

What does the below statement ( in quotes) indicate. Is it  referring to the AP itself ( different models ) or the antenna that is  used on the AP?

"Factors that determine which data rate is , the power of the device's Wi-Fi radio transmitter/receiver"

Does an AP model influence the throughput or better coverage OR is it the antenna? Which one should we see as more dominant.

[Scott Fella]

"Factors that determine which data rate is , the power of the device's Wi-Fi radio transmitter/receiver"

This means that client devices can come with various TX power.  If you look at the data sheet for client wireless cards, you might see various different output power.  For example, 100mW, 50mW and or 25mW.  There are even some in the 200-300mW.

When you implement a wireless infrastructure, you want to match the power of the lowest client you have.  Many access points can be configured to the max for the country your in (allowed by regulation).  So if your access point can achieve 100mW but you have clients that are 50mW, then you may want to lower the power of the access point to 50mW.

Power or TX power on the access point will affect the coverage area, as the higher the power, the more the coverage. If you over power the clients, then the clients can hear the AP, but the AP might not hear the client.  That's why its important to adjust the power on the AP to your lowest client.

Thanks,

Scott

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[suthomas1]

Thanks , that was helpful.

I do see that in some AP's the dot11 radio interfaces shows as 802.11a whereas in some AP's the same interface shows as .11n.

So, does it mean the AP's auto adjust to the speeds depending on various factors. Is there any way we can force them to operate on n speeds, specially on mesh networks.

[Scott Fella · Accepted solution]

No you can't.... if you try to set a limit and the AP and client can't negotiate that rate, well the client will not connect.  This is how wireless works, the closer you are to an access point, the better connection and possible better throughput, the further away, the less.  Increase your coverage to provide better data rates for clients, but that will require more AP's.

Thanks,

Scott

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[Leo Laohoo]

So, does it mean the AP's auto adjust to the speeds depending on various factors. Is there any way we can force them to operate on n speeds, specially on mesh networks.

At the end of the day, it is the client which dictates which AP it will join, what data rates to use and what radio to use.  AP is there to provide the options available.