[asterisk-users] OT - Is handover included in DECT GAP ?

[Michiel van Baak]

On 12:28, Thu 10 Jan 08, Robert Lister wrote:
> On Thu, Jan 10, 2008 at 11:22:29AM +0100, Olivier wrote:
> > Hi,
> > 
> > Do you if a DECT-GAP (or DECT-CAP) compliant handset MUST or MAY support
> > roaming and handover and are these functions transparent for handset (then,
> > these functions are implemented in DECT base stations) ?
> 
> Yes. It is a capability of the handset, where, as the user is moving about, 
> the handset is continually scanning for the best channel/frequencies 
> available from the base station. If a better signal than the one the user is 
> currently using becomes available, (perhaps they have gone into a different 
> room or moved behind a tree etc. meaning the current channel is weaker, then 
> the handset will switch to using the better channel during the call.)
> 
> There are a few systems out there that support multiple base stations which, 
> to the handset, all look like the same registered base. (i.e, the handset 
> only registers/authenticates once with the system (and not every base 
> station) and then as the user moves about the handset, by virtue of always 
> looking for the best channel, will hop from one base to the next. It does 
> require that the system in the middle manage the database of registrations 
> etc.)
> 
> I've seen such capability on Siemens HICOM and Bosch PBXs, for example. All 
> the DECT base stations are wired back to a central card in the system.
>  
> I don't know if there is a standalone DECT IP offering supporting similar.
> 
> The timing/clocking to support seamless roaming between the base stations is 
> complicated and has to be very precise, so I imagine that such a system 
> would need to have one central controller (and the SIP gateway function) 
> with DECT base stations all wired out from there, rather than lots of 
> independent DECT bases with Ethernet, that talk to a central unit over IP 
> and somehow hand off the call.
> 
> So to span multiple buildings you would probably need dedicated copper pairs 
> or fibre to connect in the remote base stations to the central system. 
> 
> That is certainly the way it worked when I was last tinkering with DECT 
> stuff. Although the Siemens switches could have multiple remote shelves 
> connected over fibre to different buildings, the DECT bases all had to be 
> connected via copper cables (and be powered on by) a central card in the 
> main shelf, and could not be connected to a card in a remote shelf. (Or, you 
> could have multiple PBXs and handsets roaming between different systems, but 
> that starts to get expensive for maybe 10 users!)
> 
> I have some detailed specs on it somewhere if you want more technical info.

We have 2 different setups in production.
NEC-Philips ip-dect and the kirk/tiptel ip-dect.

The NEC-Philips one works with a dedicated server to
controll the registration etc, and all the radios are
connected to the normal ethernet network. No need for
dedicated copper/fiber, they simply communicate over the lan
with the central provisioning/managing server. The handsets
register with the closest radio and from that moment on they
can roam to all radios. Asterisk sees every handset as it's
own sip entry.

The kirk setup we deployed is with the skinny firmware.
It works basically like the NEC-Philips setup, but you dont
need a dedicated server to manage stuff because the main
basestation does this for you. It works with repeaters
instead of seperate base stations. As long as the repeater
can reach another repeater or the base station roaming works
fine. I read in their brochures you can also stack
basestations in multiple locations but I dont know how that
works.

-- 

Michiel van Baak
michiel at vanbaak.eu
http://michiel.vanbaak.eu
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