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PREVIEW: Windows Mobile 5.0 supports concurrent and seamless WAN and W-LAN data connections
Posted by Arne Hess - on Sunday, 31.07.05 - 19:13:03 CET under 08 - Reviews - Viewed 29131x
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Finally; it took until Windows Mobile 5.0 but now it is there - Microsoft's Windows Mobile 5.0 now supports simultaneous data connections (e.g. W-LAN and GPRS/UMTS) including seamless handover between both connection types. While GPRS is at least (depending on your country) always available, W-LAN isn't but only at home, in the office or at selected HotSpots.
On the other hand, in most cases W-LAN is way faster and in most cases cheaper than GPRS (or UMTS) and therefore a W-LAN connection is preferred in most cases.

With the seamless handover "dual-connection" you can stay connected via GPRS, for example to MSN Messenger or your E-Mail server. However, as soon as you reach a (recognized) W-LAN access point, Windows Mobile 5.0 connects to this connection in addition and switches the internal data routing from the WAN (GPRS or UMTS) connection to the LAN (W-LAN/Wi-Fi) connection:

As you can see above, first I was connected with the O2 GPRS network only. However, as soon as I've reached my apartment, the device recognized my home W-LAN network and connected with it in addition.
A short check against my web-server confirmed that I was accessing the::unwired through my DSL line now instead of the previously used GPRS data connection.

If you leave the W-LAN covered area again, the device disconnects from the known W-LAN and continues seamlessly with the previously used GPRS (or UMTS) connection and isn't dropping your current online services (such as MSN Messenger).

As I said, this is pretty handy for always on services like MSN Messenger, E-Mail (or FTP) but also useful to get the full GSM service-support while you are connected with a W-LAN network. For instance, right now with Windows Mobile 2003SE, you will not receive MMS messages while you are connected though W-LAN (all you get is the notification that a new MMS is waiting for download) as well as you are not able to send MMS messages while connected because 2003SE supports one connection only. This means that you have to download waiting MMS messages later as well as you have to send them later by pushing you MMS client to send them now.
Now, with Windows Mobile 5.0 you don't have to think about this anymore as well as you will always be able to use the cheapest (and fastest) connection type for your Internet connection.
As far as I've seen W-LAN always have the higher priority over cellular connection types which means a Windows Mobile 5.0 equipped Pocket PC is always using the faster W-LAN connection over a slower (and in most cases more expensive) GPRS and/or UMTS connection.

Pretty cool! :-)

Cheers ~ Arne


Related Articles Windows Mobile 5.0

Posted by Abdul on 01.08.05 - 15:02:53

So Arne, how about a GPRS Class A PPC phone device? (Sorry If we already have any) Let's say if I'm at a location where there is no W-LAN available and my MSN session disconnects from GPRS whenever I receive a phone call. And besides having a class A device, do my operator needs to support simultaneous GPRS data and GSM voice services?

Posted by Arne Hess on 01.08.05 - 15:45:33

Abdul wrote:

So Arne, how about a GPRS Class A PPC phone device? (Sorry If we already have any).
Do my operator needs to support simultaneous GPRS data and GSM voice services?

I'm even not aware of any Class A GPRS devices so no, there isn't a Pocket PC Phone Edition device with suportof Class A available yet nor is one on the horizon AFAIK.
And yes, AFAIK carriers have to support Class A in their GPRS networks also, at least for billing.

Posted by Utente Anonimo on 02.08.05 - 12:31:02

UMTS phones will not disconnect your GPRS connection(s) when you receive a call. They even support more GPRS connections at the same time. If this is supported by Windows Mobile 5 UMTS module it's another story and perhaps something Arne can check with his device....


Posted by Arne Hess on 02.08.05 - 13:44:28

@Utente Anonimo: Yes, true. Basically all UMTS devices (should) support (to speak in this term) "GPRS Class A" and I've tested it with my Universal: works fine. I can surf the Internet in parallel to voice calls! smile Finally!
For 2.5 GPRS (even if it should/will be supported by WM 5.0) it wasn't possible to have two GPRS sessions in parallel (let's say one for Internet and one for WAP).
If I connected to Internet first and tried to connect to WAP second, the Internet connection was disconnected first and the WAP connection was established after.
Not sure if this is due to the early development device I have or if it isn't implemented into WM 5.0 yet of if it is a limitation of the radio stack used with the WM 5.0 device I used for the test.

Posted by Utente Anonimo on 03.08.05 - 15:46:46

I think the operator can configure how many PDP contexts (GPRS connections) you can open at the same time. Most operators will allow only one at a time; so voice + 1 GPRS will work, 2 GPRS towards different APNs will not, even if the phone potentially supports this option when under UMTS coverage.


PS: do you need help to test your HTC Universal? smile

Posted by stef on 29.03.06 - 13:47:33


I am slightly confused by your post.

You write the OS will always use the cheapest connection (WiFi)
You also write that now you can send MMS while in WiFi coverage.

These two statements seem to contradict each other (I am probably missing something) Will the OS not attempt to send the MMS over WiFi (and of course the MMS will not find its destination) ?

I understand that you can receive incoming MMS but don't understand how the OS can decide which data to send via which network if connected to both

Posted by Arne Hess on 29.03.06 - 14:07:18

No, it's way easier as you think. The device knows that it can not use WiFi for MMS and therefore it always takes the WiFi connection (basically the WAP settings) to send MMS messages, even if the device is connected to WiFi.
In the past it happened, that the device only recognized that it was connected to a IP connection and tried to send the MMS through this IP (WiFi) connection which failed. Now, with a more intelligent routing table in the device, it takes WiFi for Web, E-Mail, MSN, etc. but isn't using WiFi for MMS since it knows that WiFi connections aren't working but dials into the GPRS network instead.

Posted by Rolle on 20.06.06 - 11:19:10

Is the handovers really *seamless*? That is, if you download a file using WiFi, and during the download lose WiFi connection, will it just resume the download on GPRS? This would require some sort of virtual IP or Mobile IP implementation.

/ Rolle

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