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Greetings All,

Am looking to start a discussion about the WiFi standard and the use of Wireless Technologies in rural areas.

First let me say that running a rural ISP/WISP is a challenging task and that we are always encountering new issues and problems.

Earlier this year during a planned expansion of our Wireless Network, we surveyed equipment manufacturers, as one of our criteria was to add the ability to roam for certain clients as well as our techs.

We settled on Company "X". (I think for discussion that the name of the company is not relevant). After starting the implementation of the new equipment we were immediately met with problems and issues one after another.

After several months of working with Company "X" support staff we were never able to get things working properly.

(Here I might show a bit a ignorance as I am still digging into the standards in more detail, so the information provided is based on my assocaition with another tech, not personal first hand knowledge).

We replaced the AP from Company "X" with an AP from Company "Y". The AP from Company "Y" is not based on some of the newer standards and technologies as was the equipment from Company "X". The AP from Company "Y" just plugged in and worked accomplishing things that were before impossible.

According to my associate, he believed the problem is related to the transmission timing windows. He indicated that the timing windows by standard are set extremely short. This setting keeping the distance of the connection between AP and client short (up to maybe 3 miles).

In this discussion, I would hope to get pointers from folks here on the forums about this issue, where to find relevant detail about the settings for these variables and how to possibly found out how to get those kinds of specs from the manufacturers so that one can evaluate new equipment without having to suffer as we have done on this project.

I should say that I have clienths that connect to my system at distances of 8.5 to 11.5 miles.

I would hope that we could get a discussion going on this type of subject.

I would also admit that I everyday I keep learning something new about the Wireless field and its technologies.

Keith,
I used to own a WISP and currently consult for two of them, however one is a fairly small company. The other is much larger. With that said, I am always trying to learn more. I am not a dedicated tech to WISP's, but I have made quite a few improvements since working with the large client.

The "timing" that your colleague is referring to is called an ACK timeout. With the distances you are dealing with it could definitely cause a problem. Here are the details of the problem:

When a device transmits a directed frame, it expects an Acknowledgment (ACK) within a certain amount of time. If the transmitter does not get the ACK within this period of time, it will assume that the transmission was corrupted and resend the frame. What really happened is that the transmitter didn't get the ACK in time because of the distance that the frame had to travel. Even though RF travels at the speed of light, it still takes a measurable amount of time to travel the distances you are speaking of. Now, the receiver does send the ACK as it is supposed to, but since the transmitter got impatient (ACK timeout) it will resend the frame, which will collide with the impending ACK.

So, that causes serious problems. The WISP?¡é?€??s that I work on don't have these distances between the AP and the client.

You need an AP that can configure the ACK timeout value. Or, if the AP was designed with WISP's in mind, it may be set higher by default. If you don't want to reveal the manufacturers in the open forum, you can PM or email me. We have found a very good AP that I can recommend, but I will have to check to see if it has an ACK timeout value.

I have some questions for you if you don?¡é?€??t mind taking the time.

- Do you have the RTS/CTS threshold set on any of your devices?
- What brand of CPE are you using?
- Are you using omni antennas or sector antennas on your towers?
- Do you have multiple towers?
- What is your customer density per AP?

I look forward to hearing back from you!

gene@gthill.com