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New Member

802.11a/g multiple issues

Hi guys

We are about to start installing a Wireless LAN in our company HQ, using AP1200s. We had hoped to implement exclusively 802.11a, but have been EXTREMELY disappointed with the range.

Even when the AP is in the same room as my laptop, (only 3 metres away), signal strength is never 100%, it is more like 75. And if you go out into the corridor, the signal almost drops off totally. I placed the AP in a clear position on top of a pile of boxes with 1 metre space between it and the wall, then went out into the corridor exactly on the other side where the ap was facing. My link dropped to 'poor'.

My speed didn't even step down from 54Mb/s, and when I moved another two metres away I lost the association completely.

I had tried this previously with another manufacturer's access point which we had on trial (which used 2 diversity dipoles as opposed to Cisco's 'paddle' antenna) and I was able to have a good, consistent signal in both the corridor, AND in the office across the corridor. The speed did drop to 36Mb/s, but I was completely happy with that.

I was hoping for at least the same with my Cisco 1200s. I tried the paddle antenna in a number of different positions but the results were virtually the same.

Has anyone else experienced such poor results with 802.11a? Why did my speed not step down from 54Mb/s? According to Cisco, the quoted range for 802.11a at 54Mb/s is 13 Metres. The complete diameter of my office, through the corridor to the end of the opposite office is only 10M (through two unremarkable walls), and I would have been happy with 36Mbs (as I got on the other mfrs kit).

Comments would be extremely welcomed.

Unfortunately, our budget will not stretch to putting an ap1230a in each office/room, so we are now looking at a solution where we will use mostly 1231g's, but have dual band (1231g/rm20a) in our meeting rooms.

When presented with two good signals from a dual band ap (ie one 'a' and one 'g') is it possible to configure clients so that they will always associate with the 'a' radio instead of the 'g'. Given a dual band environment, I would always like them to associate with the 'a' radio if possible, even if they are receiving a perfectly good 'g' signal.

Also, when they leave these meeting rooms, how seamless will the roaming be between 'a' ap and 'g' ap? Will this present any issues, or is it just like roaming between two 'a' or two 'g' aps? (I have not been able to try this yet as I am still waiting for the CB21AG cards to be released).

Thanks, in advance, to anyone that can offer any help or answers.

Regards,

Martin

2 REPLIES
New Member

Re: 802.11a/g multiple issues

802.11a is great but the problem is not necessarily range but the size of the waveform it uses. At 5.8ghz a's waveform is 2". So, the smaller the waveform the more prone it is to interference and obstructions. That is why the 2.4ghz "seems" better range wise for the waveform is 4.2" thus the larger the waveform the less succecptible to interference/obstructions.

The faster the frequency, 5.8ghz for example, the smaller the waveform.

New Member

Re: 802.11a/g multiple issues

also, make sure the data rate setting are set for "enable" and not "require" on the .11a interface page so that the speed will fall back.

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