Multiple WIFI Access Points in one building working with WiFi Handsets
Submitted by jscanlon@storm.ie on Sun, 01/06/2008 - 6:32am.
Hi There,
I am quite new to Trixbox and would be grateful for some advice.
I have installed Trixbox ver 2.2.4 in a large building, (Old building with thick stone walls approx 30000 sq ft). I have a number of fixed phones installed around the building (11). The problem i am having is that calls are being missed as i dont have anybody answering the phone all the time. My solution would be to have a number of wifi phones that can roam around the building. I have installed a number of ZYZEL G3000h access points. These provide complete wifi coverage throughout the whole building, and have purchased a a UTStarcom F1000g wifi phone.
I am new to wirelss technology and thus do not know exactly how to configure my Access points. For example do i configure them with the same SSID etc.
My UT Starcom phone will register on the network and works fine. The problem i am having is that it drops the registration while walking around the building even though there is complete wireless coverage.
I would appreciate any advise
Thank you
Justin
You'll want to configure
Sun, 01/06/2008 - 6:57am
You'll want to configure each AP with the same SSID and encryption details but on different channels. You should have overlap with coverage but each adjacent AP should be a different channel. AP1-ch1, ap2-ch11, ap3-ch6, etc
Some WiFI devices roam better than others.
You are going to need a much
Sun, 01/06/2008 - 7:09am
You are going to need a much more intelligent wireless deployment in order to pull off wireless roaming. First, to have good and reliable coverage the access points (AP) will need to have proper channel separation so no two AP's have a common common channel overlapping. Next, based on channel frequency separation, assuming the AP's are b/g, channels 1,3,7,11 are usable with many folks limiting to three channels.
Now why are the calls dropped... Every time you move to an area where client wants to associate with a new AP, based on how the client wireless device senses AP signal strength, it is seen like a completely new network connection dropping any active connections. Much like a cellular tower, if there was not intelligence to deal with the rerouting of an active stream prior to a change in tower, a cell phone call would drop. The same holds true for wireless networking. Manufactures of wireless switches have solved this problem (or at least think they have for voice. I have seen good data results, mixed voice results) by having a centralized management of wireless connections (the switch) with thin AP's, all communicating to the manager. This way they can cleanly hand off the stream giving you a roaming capability.
Multiple WiFi Access Points
Sun, 01/06/2008 - 8:39am
WiFi and VoIP and roaming
Sun, 01/06/2008 - 9:49am
Until 802.11r is available you have to look at deploying a thin AP model like Trapeze or Avaya.
The cost of roaming can result in lost connectivity.
You MUST NOT 'hide' the SSID. See my paper on the Myth of Hiding SSIDs.
WPA with Radius is pretty dead. WPA with PSK barely works (but see my paper on attacking WPA-PSK). Of course most phones do not support a full 802.1X supplicant so you may well be limited to WEP anyway. Or WPA-PSK at best.
In the thin AP model all that you deploy are AP radios. The whole AP code is centralized thus the roaming is only at the lower radio level and does not require all the negotiation traffic.
whilst all the above are
Sun, 01/06/2008 - 10:23am
whilst all the above are correct, the UT starcom handsets do NOT roam wirelessly!
Other handsets might do this, but the starcom will always keep to the same AP that it started the call with. It will only switch to the highest strength access point when it is idle and not in a call!
our expirience with roamin
Wed, 01/09/2008 - 8:46pm
I set up an experimental wifi network for the maintenance department (three employees) of our local county government. We used the lowest-cost Wireless G access points from Linksys, and we tried three brands/models of phones: the UTStarcom F1000g, the Linksys WIP300, and the Linksys WIP330.
The end result is we scrapped the whole thing and went back to using two-way radios.
The F1000g was terrible - sound quality problems, various stability problems, etc. We didn't get past first base with this one.
The WIP300 was much better. It did roam, but usually you'd get a period of silence when it switched over - it wouldn't do so seamlessly. The main problem with the WIP300 is that sometimes when it was trying to switch access points it would freeze and the screen would go dark, requiring a long wait or a hard reset by removing and reinserting the battery. Also, the battery would not last more than a day without recharging. For casual non-business use, this phone was good enough, but not for business. The WIP300 had a nice web based admin interface, and the sound quality was decent.
The WIP330 is based on Windows CE and felt like a more expensive phone (in case you didn't already notice when you paid for it). It was heavier and sturdy than the WIP300, the high res screen was beautiful, the sound quality was excellent, and the battery life slightly better than the WIP300. But that's where the love affair stopped. The boot up time was very slow (could it be that Microsoft releases bloated software from time to time?), and the roaming was perfectly awful. The phone would cling to the currently connected access point until it's dying breath, even though another AP beckoned from only a few yards away. After finally giving up on the old access point it would connect to the new one - after 30 seconds to a minute of waiting. Also the WIP330 didn't have a web-based administration interface, which made fine tuning the config much harder. Nor did it have as many detailed settings as the WIP300.
Our access points were configured with the same SSID but on non-overlapping channels.
I'm sure there are APs and WiFi phones out there that would have met our needs, but at this point, we've decided to wait a few years and give the technology a chance to mature.
Hopefully this helps - I figured others may as well profit from my misfortune.
Cheers,
search our forums here,
Wed, 01/09/2008 - 10:36pm
search our forums here, there have been a few threads on this (cosmicwombat comes to mind as a poster and some others).
I think the access point does play a good role in it, like Eldon may have found, if I remember right I think there were some people using the Hitachi 5000 series phones. Also Senao has a phone (wasnt public last I checked) and they make the $500+ Engenious cordless phones that are pushed as the elite of elites as far as 900mhz cordless goes - should be a good unit when it is released (one user got a demo and said it was great).
Or for a good wireless phone - the Aastra 480iCT and 57iCT are awesome - they are 900 mhz dect, and the useability is great, I can go outside my brick warehouse, and down the street a block- about 1200 feet.
hope that helps.
Member Since:
2007-12-10