Intermec AP with Cisco PC card roaming problem

[zhuyi]

Anybody know how Intermec Mobile Access 2100 working with roaming eviroment, and how it works with Cisco 4800 PC cards to roam with?

The problem now is terminal with cisco cards use too much time looking for the good intermec AP untill it lost the connection with exiting AP it can't synchonize with the new AP. Any idea?

[wirelesssguru]

Hello,

Have you used other cards other then cisco?

[zhuyi]

We use Cisco's cards only.

[JimGeier]

I'm not sure exactly how the Intermec access points implement roaming, but I've seen this same problem a few times before. Once was with Proxim access points (which I believe Intermec private-branded in the past) and the same radio NICs that you're using (Cisco/Aironet 4800). In this case, I found that the access points didn't have any radio wave overlap. Once we moved the access points closer together to provide adequate overlap, roaming was very responsive. I'm not sure, but I think that these access points implemented roaming by communicating from access point to access point over the radio network.

A similar case involved improper antenna orientation. Someone had turned the access point antennas to be level with the floor, which cause the antennas to have a relatively narrow horizontal propagation pattern (with a gap between access points). The solution to this one was to turn the antennas straight up (90 degrees with the floor) as they should be to maximize horizontal propagation (which provided overlap between the access points).

Another scenario that will cause this same problem is when the neighboring access points are set to the same channel. Some of the older radio cards (e.g., Cisco/Aironet 4800) will not include its currently-associated access point channel when scanning for new access points. As a result, it will skip an access point (possibly one that would provide better connectivity when roaming) set to the same channel. Of course you should set the access points to different channels to avoid inter-access point interference, but it also improves roaming.

[zhuyi]

This is in a container yard. the distance between APs are less than 100m and all AP configured with 2 9dBi omni antennas, so they have enough coverage and sure with different channels.

We feel the problem is not of one AP's coverage space is too small but too big, and it always can't have good signal when you very close to an AP, so we tilt down the antenna a liitle to the ground but not straight anymore, but there is no improment untill we change the antenna to 2dBi omni antenna. BTW, this is in container port.

We had the same experience that in indoor eviroment, a 2dBi omni antenna from Intel can get more coverage than a 6 or 9 dBi omni antenna from Morbilemark for times, and I just can't understand?

[dbuss]

The lower gain antennas will give you a better signal close to the antenna site then the higher gain antennas. The higher gain antennas will propogate the signal above the close in coverage area and the signal does not get to ground level. Mechanicaly tilting an omni directional antenna will most probably not result in better close in performance. Generaly speaking the lower the gain on the antenna the better close in range you will get. Of course you will sacrafice the longer range you will get from a higher gain antenna.