25 Oct 2004

the mystery of 1Mbit/s bluetooth

so it has been often touted that bluetooth can get up to 768kbit/s data rate (1Mbit symbol rate). but actually in practice, you'll find that OBEX transfers only get up to 16-20KByte/s (eg. 120~160kbit/s). it seems like the CSR chipset's spec sheet states that you can get a RFCOMM data rate of only up to 350kbit/s. so even that doesn't explain why the transfer rate we actually see is nearly half as slow. is it that the nokia's bluetooth stack doesn't even get up to 350kbit/s?

what is even worse, on OBEX transfer between a CSR and Broadcom dongle is even slower! someday i'm going to do a proper benchmark of all this crap.

(correction: i just made a simple patch against gnome-bluetooth-0.5.1 that displays the transfer rate during the transfer, and actually, Broadcom to CSR achieves a sustained transfer of 25KB/s, Broadcom to Nokia is around 17KB/s, and Broadcom to Apple Powerbook is a disappointing 7-9KB/s plus random drop out after transferring ~90KB!?)


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