nRF52840 throghput question

RE: nRF52840 throghput question

Soojin — Thu, 24 Sep 2020 09:43:00 GMT

Thanks Kenneth! Loads of help.
Have a great day.

RE: nRF52840 throghput question

Kenneth — Wed, 23 Sep 2020 08:34:54 GMT

[quote user="Soojin"]So according to this data, if I Set ATT MTU size to 247, LL payload size to 251, Connection interval to 50ms and use LE 2M PHY, will I be able to get the maximum throughput??[/quote]

That will be the peak throughput yes with no packet loss. You may also check out this slightly old thread, but should still be valid:
https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/throughput-and-long-range-demo

RE: nRF52840 throghput question

Soojin — Tue, 22 Sep 2020 15:25:25 GMT

Thanks! Now I got PHY LE 2M working:)

So, now I think I changed every component.

According to one of Nordic's site, I found this chart
( https://infocenter.nordicsemi.com/index.jsp?topic=%2Fsds_s140%2FSDS%2Fs1xx%2Fble_data_throughput%2Fble_data_throughput.html )

From here, the maximum data throughput I can get is 1327.5 Mbps.

So according to this data, if I Set ATT MTU size to 247, LL payload size to 251, Connection interval to 50ms and use LE 2M PHY, will I be able to get the maximum throughput??

RE: nRF52840 throghput question

Kenneth — Tue, 22 Sep 2020 13:09:49 GMT

Hi,

You may want to check out this example in general:
https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.2/ble_sdk_app_att_mtu.html

To answer your questions:

1. #define MIN_CONN_INTERVAL MSEC_TO_UNITS(5, UNIT_0_625_MS) is not a valid value, so not sure what may be happening here (maybe it defaults to a higher value). In any case having larger intervals than 7.5ms may actually give higher throughput numbers, however you are trading interference performance vs. stable throughput. Because if you have larger intervals you may pack the packets closer together, however if you have packet loss it will need to wait until next interval before it can re-try. So even though using longer intervals can give higher throughput in ideal conditions with no packet loss, it will be lower throughput in a realistic scenario with other 2.4GHz devices in the proximity.

2. It may seem as you are mixing advertisement and connection parameters here. In this specific case you are interested in the throughput during a connection, so you should check the BLE_GAP_EVT_PHY_UPDATE event for the active data-rate. Check our message sequence chart:
https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.s140.api.v7.2.0%2Fgroup___b_l_e___g_a_p___p_e_r_i_p_h_e_r_a_l___p_h_y___u_p_d_a_t_e.html

Best regards,
Kenneth