Too high throughput?!

RE: Too high throughput?!

run_ar — Thu, 03 Nov 2016 15:51:08 GMT

Yes, I can see that 8 packets are transmitted in one event in the log you attached. So I assume you are able to fill the tx buffers that is freed during the connection event, since only 6 buffers will be available prior to the event. As far as I can see from the log it looks as if windows could receive more packets as well.

RE: Too high throughput?!

KingKarl237 — Thu, 27 Oct 2016 14:03:08 GMT

Here is the Wireshark file: LINK The first byte of my message is an ongoing counter, as you can see in the code above.

RE: Too high throughput?!

run_ar — Thu, 27 Oct 2016 13:50:47 GMT

So, Long att MTU's is the size of the packets in the gatt server beeing larger that 20bytes of data. It can be transfered using the default LL PDU size by using fragmentation and recombination. DLE is data length extension, where the PDU size is increased to e.g. 251 bytes in one radio packet.

Can you upload your sniffer log so I can have a look at it?

RE: Too high throughput?!

KingKarl237 — Thu, 27 Oct 2016 13:09:21 GMT

How many packets per connection event are possible with S132v2? Everyone is speaking about 6/event, but if i look on wireshark and on my measurement i think it must be 8: 20Byte * 8 * 1000/7,5 =21,3kB/s

RE: Too high throughput?!

KingKarl237 — Tue, 25 Oct 2016 13:34:17 GMT

i have added some information. Can you explain where the difference between a longer MTU and the DLE is?

I have a sniffer ready here too. But he can just show one packet/connection Intervall right?

RE: Too high throughput?!

run_ar — Tue, 25 Oct 2016 11:30:33 GMT

The throughput depends on your connection interval, the packet length, and the number of packets you can send in one connection event.So lets say you send:

20 bytes of actuall data (default MTU size of 23 bytes).
6 packets per connection event. = 120bytes /event
7.5 ms connection interval.
= 120*1000ms/7.5ms = 16 000 Bytes/s of actuall data excluding headers.

Then if you use longer MTU's without DLE, e.g. 158 bytes, you will be able to send 20bytes + 5*27 bytes of actuall data in one connection event:

20 + 5*27 bytes of data. (only the first packet has 7 (4+3 bytes)bytes of header)
6 packets per connection event. = 155bytes /event
7.5 ms connection interval
=155*1000/7.5 = 20 666.6 Bytes/s of actuall data.

It is also possible to enable data length extension for even higher throughput. But this is not supported in S132 v2. But you can see data throughput examples in the softdevice specification.