[TommyMo]

Hi everybody,

does anyone of you know if it is possible to develop an bluetooth application with J2ME technology on mobile devices which is able to communicate in an ad-hoc manner?

For my masters thesis I have to evaluate the possibilities of Bluetooth in a mobile ad-hoc network. Therefor I should create a program in Java (J2ME, WTK 2.2, Eclipse 3.0 with wireless plugin) in which it is possible that mobile devices (mobile phones, PDAs) can interact with each other in a Scatternet formation. When I have two Piconets for example, where one device is a Slave in both Piconets, I would like to have the possibility to send messages from any device to any other device in this Scatternet. Therefor I want to implement routing algorithms in my program.

Building on that a device A could send a message to device D, which is not within the range of A, via devices B and C, which are within 10 m range of each other. So B is in range of A, C is in range of B and D is in range of C.

Is that possible via J2ME and do I need JSR-82 enabled devices which can handle more than 1 connection? Do I have to use L2CAP-API. Da I need to implement a Push-Registry? Is it possible to create a "peer" on a phone (BT-Server and BT-Client are running in two threads),?

Thanks in advance,
Thomas

[seppo_fn]

First of all, we need an application (protocol) running on all involved devices to handle and forward the messages back and forth.

Second, how do the devices know of each other?
Assume that devA knows the BD_ADDR of the target device (D). Then it finds device B in the vicinity (running the same app) to forward the message.
The devB runs a device discovery, does not find devD but finds devC (again, running the same app).
Then devC runs a discovery and finds devD - running the app - and sends the message to it.
Each device has to check the (proprietary) header of the message to see if the message has arrived in its target or if it needs to be forwarded.

Each time, after the message is sent to the other device, the connection has to be closed, to enable the forwarding (connection to the third device).

If you only have three devices from sender to the final receiver, the second deviceB (router) could have two simultaneous connections to devA and devC. But also in this case, the first connection from devA to devB has to be closed first, as the devB has to be the master to both devA and devC. Please note that current Series 40 devices do not support point-to-multipoint so they cannot act as a router; in Series 60, Series 80, and Nokia 7710 devices this is possible.

Now, how convenient and fast is this kind of messaging - that's another question...

-seppo
Forum Nokia

[nanotalk]

What kind of handsets support JSR-82?

[TommyMo]

Hi seppo,

thanks for your reply! This sounds very interesting!
As I found out until now, there are only Point-to-Multipoint enabled devices on the market, but no Scatternet enabled devices, which support switching between two piconets. Or do you know any Scatternet enabled devices from other vendors than Nokia?

So the best choice would be to build a Piconet chat, where the Master sets up connections to all of its Slaves (max. 7, if the device supports that). I would do this with a Nokia 6600. It can handle up to 6 connections afaik! Is it possible to build such an application?


Thanks,
Thomas