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WiFi

I have a student accomodation with 8 Cisco Aironet AP's with different SSID's covering 5 floors. Most of the units are in cupboards with 2 3 ft aerials which are also in cupboards. Sometimes the wifi clients lose connection and the bandwidth they receive using speedtest.net can be about .49 mbits. The internet connection is 100mbit and there are policies on the firewall that restricts each ip to 4mbits. Plugged directly into ethernet and the upload/download is 4mbits. Each AP has a dynamic ip.

I am proposing to have SSID's all the same so that the laptops can pick an AP with the best signal as they roam the building and move the antennas that are in the cupboards into the corridor so that they are more visible. Is there anything else that can be done to improve wifi signal? How many clients can an AP handle? I am using iStumbler to test the signal. Next to the unit I receive a reading of 76%, how accurate is this?
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Commented:
Stumbler is somewhat accurate but I would suggest using airmon suite or some other flavor of linux with atheros chipsets or a professional card like alfa.  That way you have some control over the hardware and you can fully manage what you are monitoring.  Also having access points with the same name may cause gaps when people are umping back and fourth if the signal is similar.  you coul try changing the antennas.  
You are on the right track with making them all the same SSID.

I would also suggest static IP addresses for each (for ease of monitoring and configuring) and then the best way to improve your wifi reliability will be to have them on different channels.

A good example is: http://setup-wireless.blogspot.com/2008/12/setup-multiple-access-point.html

The last diagram shows a good setup to ensure full coverage, just make sure that all are on seperate channels with the same SSID and you should be good.
Also consider the direction of your antenna's and the way that the transmission wave is expelled from it.

A very overlooked factor in Wifi is the antenna type, it's one of the biggest factors in signal strength.

Commented:
All the above answers are good. Configuring all the AP's with one SSID will allow you to roam as you please, automatically connecting to each AP as you move. Right now I manage a 30 floor building with 4 AP's on each floor. I assign them all static IP's from a management VLAN and staggar their channels so interference isn't an issue. For example, the Northwest and Southeast corners would be on channel 11, the Southwest corner would be channel 1 and Northeast would be on channel 6. The floor above would make the Northwest corner channel 6, Southeast Channel 1, and the Northeast and Southwest corners channel 11. This reverses the layout and keeps signal interference from being an issue. Now, if you're on two floors of a shared building you'll want to run some kind of wifi analyzer from each corner to help you determine which channel would be best. Now, this next suggestion is really a cheap, but useful tool - if you have an Android phone. Purchasing a real analyzer can be expensive, but I found an android app called WiFi Analyzer that allows me to wirelessly scan the area I'm in and tells me what ssid's are being broadcast and what channels they are on. I have found this app extremely helpful in determining channel interference. Again, this isn't a solution if you're a consultant doing a site survey, but for this purpose it would come in handy and help you! This program has helped me locate channel interference on many occasions.

Another idea would be to order high-gain antennas and install them on the AP's. This will help you with converage and signal strength.

What model AP's are you working with??

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Commented:
Kuleaze, the current APs are 1240AG, I am not sure how they are configured as I do not manage them. We setup as a demo 1231g which are older access points based on your suggestions.

In scenario 1 we placed the units on the ground and 3rd floor and gave them the same ssid as the 5th floor, same wpa password and different channels. We were able to roam between floors and the laptops/iphone was able to reconnect when the signal was lost in the lift. The iphone connected automatically as it was constantly looking for a signal. The laptop we had to to close the lid then reopen and it would automatically connect.

In scenario 2 we placed both units in the same classroom with the channels far apart. They had the same ssid as the AP on the floor above.  I lowered the power just enough that when a student opens up their laptop they will connect to the strongest signal. Previously they would connect to the floor above and they would eventually lose connection.

Most of the 1240AG APs have AIR-ANT2460P-R patch antennas and all are in cupboards. When I used iStumbler the signal was higher with standard antennas than the patch antennas. I  used the diversity setting for transmitting and receiving.

We are waiting for the class on Monday, to determine if there are any improvements.

I noticed with the existing APs, in the common room which is opposite the cupboard the signal strength is in the 40's.

Commented:
Wireless can be a difficult animal to tame! You really have to watch where you place them. Are there any florescent lights around, or microwave ovens? These can wreak havok on wireless signal. Also, you have to pay particular attention to the speed of each AP and make sure they are consistent. I try to set all my AP's to the same speed, if one has higher speeds set than another in the area, computers will try to associate to the higher speed AP rather than the AP sitting right next to it. For illustration purposes, the configs of two different AP's are below:

AP 1
interface dot11radio 0
speed 9 11 12 18 24 36 48 54

AP 2
interface dot11radio 0
speed 54

I was troubleshooting a PC that was dropping wireless connectivity constantly - it turns out, even though the PC was right under AP 1, it kept trying to associate with AP 2. A PC will always try to associate with the fastest connection. I fixed this by configuring all AP's with the "speed 9 11 12 18 24 36 48 54" command. Haven't had that problem since.

In your original post you say the firewall is restricting the AP's to 4Mbs, how is this happening? A firewall doesn't have any impact on the speed of an AP.

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Commented:
The demo APs have the same speed settings. The firewall has a policy for each ip address. It does not restrict the APs. Each client ip have a limit of 4mbits.

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Commented:
Does installing APs and the antennas in cupboards have any impact on signal?
Commented:
Absolutely!! AP's should be out in the open!! Also, Cisco recommend that the antennas run straight up and down (veritical.) That's why I suggested attaching high gain antennas if you couldn't move them from the cupboard. You can get high gain antennas that have about three feet of cable attached, this would allow you to relocate the antenna if moving the AP wasn't an option.

No matter what option antenna you go with, those AP's really should be out in the open! The more objects the signal has to go through, the weaker the signal gets. If the building you're in has a lot of structure to it, then I would even lower the speed allowed on the AP even more. Lower speeds will travel farther than higher speeds. Like my example in the earlier post, 54 Mbps starts to drop at around 20 to 25 feet. 1 Mbps will hold a connection to an AP out as far as 100 feet - is that ideal, no, but it helps me explain the concept. Keep me posted, I know for a fact if you move those AP's out of the cupboard, put them all on the same SSID, and then configure them for separate channels, you'll fix a bunch of your issues.

Author

Commented:
I have installed 1231G, one in each meeting room which are next to each other. Sometimes their can be up to 10 people in each room at the same time. I get approximately 76% signal strength with the standard antennas next to the ap, at the furthest part of the room I get around 58%. Is it worth upgrading the antennas and just have one ap to cover both rooms i.e. one patch antennas per room and set the transmit/receive to diversity? What type of Cisco antennas
Should I purchase?

Commented:
How big is this room that you're only getting 58% signal strength at the farthest part of the room?? How old is this AP? The high gain antennas are around $200 give or take $20 or $30 dollars. The antenna will attach to the right connector and then you'll issue the commands below under the radio interface:

interface dot11radio0

antenna receive right
antenna transmit right

You should notice a difference with the highgain antenna. Before you go spending all that money, issue the power command to make sure you're transmitting at the max power of the AP. You do this udner the same interface mode as above.

Depending on the IOS you have installed, it should be:

power both max

If that doesn't take, issue the power command followed by the question mark (?). This will provide you a list of options that can go after the power command. You want to configure both the trasmit and client power.

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