Maximum achievable throughput of LE Audio (BAP streaming)

RE: Maximum achievable throughput of LE Audio (BAP streaming)

Maria Gilje — Wed, 22 Jan 2025 10:33:18 GMT

Hello HaiwenChen,

I can see that you are getting support for this in this ticket.

Best regards,

Maria

RE: Maximum achievable throughput of LE Audio (BAP streaming)

Hhhhh — Mon, 20 Jan 2025 14:58:22 GMT

How to calculate the throughput in LE Audio？

I use the sdu_ref and data_size in this function to calculate throughput, is it crroect? The result is 96kbps.

RE: Maximum achievable throughput of LE Audio (BAP streaming)

Maria Gilje — Wed, 19 Jun 2024 11:31:00 GMT

Hello,

[quote user="vorobeyvd"]It's great that I got almost theoretical limit. But maybe you can explain to me how I can make this transfer non-simultaneous to achieve higher bitrate between client and server? Is it possible to disable transmission from server to client? I've tried not to send any data from server to client, but the bitrate from client to server still ~770kbps.[/quote]

The control packets on the ACL link will still be transmitted, but with unidirectional CIS you should only have CIS packets from the client to the server. Have you captured the packets with a packet analyzer compatible with ISO and verified that there is no data transmitted from the server to the client?

[quote user="vorobeyvd"]Also, I tried to change SDU interval but I couldn't get it to be less than 5ms. Is this the limit?[/quote]

Currently 5000us is the lower limit for SDU interval. See DRGN-21099 in the Limitations for the SoftDevice Controller. The workaround is to use the LE Set CIG Parameters Test command to allow SDU intervals under 5000us.

[quote user="vorobeyvd"]And I tried to increase the number of CONFIG_BT_BAP_UNICAST_CLIENT_ASE_SRC_COUNT. But also stuck with some restrictions. Is it possible to have more than 2?[/quote]

You need to also increase CONFIG_BT_ISO_MAX_CHAN to reflect the value for CONFIG_BT_BAP_UNICAST_CLIENT_ASE_SRC_COUNT and increase CONFIG_BT_ISO_TX_BUF_COUNT as well.

Best regards,

Maria

RE: Maximum achievable throughput of LE Audio (BAP streaming)

vorobeyvd — Tue, 18 Jun 2024 14:17:36 GMT

Thanks for the answer. But I got more questions :)
It's great that I got almost theoretical limit. But maybe you can explain to me how I can make this transfer non-simultaneous to achieve higher bitrate between client and server? Is it possible to disable transmission from server to client? I've tried not to send any data from server to client, but the bitrate from client to server still ~770kbps.
Maybe it is possible to get 90%-10% ratio of data transfer from client and from server?
Also, I tried to change SDU interval but I couldn't get it to be less than 5ms. Is this the limit?
And I tried to increase the number of CONFIG_BT_BAP_UNICAST_CLIENT_ASE_SRC_COUNT. But also stuck with some restrictions. Is it possible to have more than 2?

RE: Maximum achievable throughput of LE Audio (BAP streaming)

Maria Gilje — Wed, 29 May 2024 10:32:27 GMT

Hello,

Thank you again for your patience.

For Bluetooth with 2M PHY the theoretical maximum throughput is ~1400 kbps. With CIS the possible throughput is somewhat smaller because both ACL and CIS packets are using the same PHY. I don't have exact values for the reduced number, but ~1200 kbps is a plausible value.

[quote user=""]I'm transmitting data every 5ms (AUDIO_DATA_TIMEOUT_US 5000). With these adjustments, I managed to achieve approximately ~769 kbps from client to server and ~391 kbps from server to client.[/quote]

Are these bitrates simultaneous? If yes: the total bitrate is ~1160 which is quite close to a potential maximum.

Best regards,

Maria

RE: Maximum achievable throughput of LE Audio (BAP streaming)

Maria Gilje — Thu, 16 May 2024 14:18:14 GMT

Thank you for your continued patience.

I have not found any significant info on this yet. I will ask some colleagues for assistance and you'll hear from me next week.

Best regards,

Maria

RE: Maximum achievable throughput of LE Audio (BAP streaming)

Maria Gilje — Fri, 03 May 2024 13:42:12 GMT

Hello,

I will get back to you as soon as I can. Thank you for your patience.

Best regards,

Maria