Medium Access Scheme in bluetooth low energy

El dorado

Hi there

Getting confused here. Suppose 10 devices enter the advertising state and send out ADV packets every 250msec. How are RF collisions then avoided? Is there a CSMA/CA scheme which does the trick, or is it simple TDMA without any knowledge at the sending side about the channel occupancy? Where can I find more info about the Medium acces techniques used in bluetooth low energy?

regards

over 12 years ago

0 hec over 12 years ago

TI__Genius 10955 points

The collision avoidance scheme for advertising packets is just randomness in the timing. A pseudo-random delay is added to the advertising interval in order to avoid repeated collisions. For SCAN_REQ/SCAN_RSP exchange, there is also a backoff procedure to avoid repeated collisions.

This is described in the Bluetooth 4.0 core specification (https://www.bluetooth.org/docman/handlers/downloaddoc.ashx?doc_id=229737), Volume 6, Part B.

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Medium Access Scheme in bluetooth low energy