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Confirmation of correct Bluetooth association via very slow 1 way/1 bit communication link Disclosure Number: IPCOM000031371D
Original Publication Date: 2004-Sep-22
Included in the Prior Art Database: 2004-Sep-22
Document File: 5 page(s) / 45K

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Disclosed is a means of confirming that a first Bluetooth device is correctly associated a second Bluetooth device. The first Bluetooth device uses a separate, unidirectional non-Bluetooth communication link to convey an indication to the second Bluetooth device. The indication starts the Bluetooth association confirmation process. (Note that this process does not establish the association.) When the second Bluetooth device receives the indication, it transmits a number representing a randomly chosen time delay to the first Bluetooth device via the previously established Bluetooth link. When the first Bluetooth device receives the random delay, it then waits the random delay and then sends a second indication to the second Bluetooth device. If the second Bluetooth device receives the second indication at the proper time, then correct Bluetooth association is assumed.

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Confirmation of correct Bluetooth association via very slow 1 way/1 bit communication link

    This idea is about CONFIRMING correct Bluetooth association. It would be used after the correct Bluetooth association was established by another means such as by scanning a bar code on the Almond2 tablet.

    Part of the core idea of this invention is to confirm that two Bluetooth devices are correctly associated with each other by establishing a one way communication link between the two Bluetooth devices when it is known that they are in mechanical contact with each other. The link would not exist otherwise. If they are in contact, then it is assumed that the devices should be associated with each other via a Bluetooth link. The one way communication link can be very slow.

    The actual Bluetooth link can be used by this method to communicate in the opposite direction.

    The key idea that makes this idea work is that the device on the receiving side of the one way link, after receiving information on the one way link, generates a random number that represents a random delay. The link's receiving device then transmits the random number, via Bluetooth, to its associated Bluetooth device. The associated Bluetooth device then waits for the time defined in the message and then sends an indication over the one way communication link. The link's receiving device measures the time that the associated device took to respond and confirms that the association is correct if the delay time was correct. This process can be repeated if it is desired to increase the confidence that the timing was coincidental.

The advantages of this method are:

A one way link is cheaper than a two way link. This idea uses the Bluetooth link itself for communication in the direction opposite that of the one way link.

The one way link can be very slow. Slow functions are generally cheaper than fast functions.

This idea can be used with varied kinds of links such as, but not limited to, the following:

If the first Bluetooth device is docked to the second Bluetooth device, the first Bluetooth device could switch the voltage on the dock holding the second Bluetooth device to indicate to the second Bluetooth device that the association confirmation process should be initiated. This approach would also enable the confirmation process to be automatically started when the second Bluetooth device is placed in the dock. This method may not require any additional hardware if there is a need for the first Bluetooth device to switch the voltage going to the second Bluetooth device in order to keep it from excessively draining the first Bluetooth device's battery. This method would not require any additional pins in the docking connector.

One device could constantly pulse a LED at a very low duty cycle. The design of the two Bluetooth devices could be such that a photo detector in the other device would not see the LED pulses unless the two Bluetooth devices are docked.

One of the Bluetooth devi...