[Bluez-devel] Development of a Bluetooth-LAN-Accesspoint

[Bluez-devel] Development of a Bluetooth-LAN-Accesspoint

[Boris Wüst]

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Hi folks,

still i have more a logical than a technical problem. i hope someone can help:

we (my projectteam) want to develop an bluetooth-lan-accesspoint based on the BlueTarget-Controller from SND (perhaps someone knows the controller) for our university. i have thought about to use the rfcomm-layer to handle the connections and the low level data transfer. on top of the rfcomm-connections i want to set up an normal ppp-connection. speaks something against this concept? have anyone a better solution?

now to the problem(s):

(1) we want to design an accesspoint that connects automatically to all bt-devices that are located in its range, so that a lan-access supported immediately and it's guaranteed that the bt-accesspoint is the master at all communications? how can we implement an automatic connection establishment on the rfcomm-layer and how we can make sure that the bt-accesspoint is always master that parks and activates the devices automatically depended on the data transfer(so that can be more devices than 7 connected to the lan)? what do we have to consider with the authentication? can we avoid it or switch it off at both sides of connection? when the connections established how we can manage them and the different channels to the connections?

(2) when we use a ppp-connection from bt-devices to the accesspoint, every device needs an ip and the accesspoint as gateway. how can we realize the assignment of the ip-adresses an the gateway to the bt-devices controlled by the accesspoint? the major problem at this concept is that the BlueTarget-Controller is a pure microcontroller an provides a own bt-stack. so on it can't be run services how pppd or pand. but the controller as an lan-interface and must therefor understand tcp/ip. how we can emulate a ppp-connection with a bt-stack(bluez) avoiding high expense of development? are there some documentations and/or program examples about this topic?? have anyone implemented something compareable??

(3)the last problem is the connection speed. we have set up an test environment composed of a PDA and a linuxsystem with the bluez-stack and a bt-usb-donlge. we have only achieved max. 16KB/s at the best bt-connection qualtity, only one bt-connection and ACL. why can't we achieve approximately the max. speed (95KB/s) of the connection? how does it look with serveral connections? share all connections these 16KB/s? how we can advance the connection-speed? is one possibility to use more than one rfcomm-connection (more than one channel) for a ppp-connection? have anyone a solution?

i hope you guys can help me with these problems. perhaps also by documentations of previous projects or links to the web. when someone of you have a lot of experience in the development in this direction, i would be grateful when you lend yourself as permanent contact person. thanks to everyone who helps ;D

best regards, Boris

p.s.: plz apologize my weird englisch *g*

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Re: [Bluez-devel] Development of a Bluetooth-LAN-Accesspoint

[Marcel Holtmann]

Hi Boris,

> still i have more a logical than a technical problem. i hope someone
> can help:
> 
> we (my projectteam) want to develop an bluetooth-lan-accesspoint based
> on the BlueTarget-Controller from SND (perhaps someone knows the
> controller) for our university. i have thought about to use the
> rfcomm-layer to handle the connections and the low level data
> transfer. on top of the rfcomm-connections i want to set up an normal
> ppp-connection. speaks something against this concept? have anyone a
> better solution?

yes, because "LAN access using PPP" is a deprecated profile. Use the PAN
profile instead.

> now to the problem(s):
> 
> (1) we want to design an accesspoint that connects automatically to
> all bt-devices that are located in its range, so that a lan-access
> supported immediately and it's guaranteed that the bt-accesspoint is
> the master at all communications? how can we implement an automatic
> connection establishment on the rfcomm-layer and how we can make sure
> that the bt-accesspoint is always master that parks and activates the
> devices automatically depended on the data transfer(so that can be
> more devices than 7 connected to the lan)? what do we have to consider
> with the authentication? can we avoid it or switch it off at both
> sides of connection? when the connections established how we can
> manage them and the different channels to the connections?

The master point does not count, because you can switch the roles at any
time. What I don't understand is why the access point should initiate
the connection. What kind of clients do you wanna support?

> (2) when we use a ppp-connection from bt-devices to the accesspoint,
> every device needs an ip and the accesspoint as gateway. how can we
> realize the assignment of the ip-adresses an the gateway to the
> bt-devices controlled by the accesspoint? the major problem at this
> concept is that the BlueTarget-Controller is a pure microcontroller an
> provides a own bt-stack. so on it can't be run services how pppd or
> pand. but the controller as an lan-interface and must therefor
> understand tcp/ip. how we can emulate a ppp-connection with a
> bt-stack(bluez) avoiding high expense of development? are there some
> documentations and/or program examples about this topic?? have anyone
> implemented something compareable??

I don't understand that. Explain what the BlueTarget controller is and
what it is doing actually.

> (3)the last problem is the connection speed. we have set up an test
> environment composed of a PDA and a linuxsystem with the bluez-stack
> and a bt-usb-donlge. we have only achieved max. 16KB/s at the best
> bt-connection qualtity, only one bt-connection and ACL. why can't we
> achieve approximately the max. speed (95KB/s) of the connection? how
> does it look with serveral connections? share all connections these
> 16KB/s? how we can advance the connection-speed? is one possibility to
> use more than one rfcomm-connection (more than one channel) for a
> ppp-connection? have anyone a solution?

The Bluetooth bandwith is shared within the complete piconet and so more
RFCOMM channels won't help. However the 16 KB/s must be a problem of
your PDA, because you will get around 60-70 KB/s depending on your
payload of the data.

> i hope you guys can help me with these problems. perhaps also by
> documentations of previous projects or links to the web. when someone
> of you have a lot of experience in the development in this direction,
> i would be grateful when you lend yourself as permanent contact
> person. thanks to everyone who helps ;D

Feel free to ask on the mailing list, but lending a developer costs
money ;)

Regards

Marcel




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