CODEWITHSUNDEEP
bluetoothbluetooth-lowenergybluetooth-gatt
Talia
Talia

Reputation: 3137

Data communication in bluetooth

in Bluetooth, I am going to send a big file which divides into 3 packets (p1, p2, p3). Each packet has the max ATT payloads.

My question is that in one connection interval, there would be a Master-slave request and then the slave would send all the packets of the file one after each other with Interframe Space (IFS) between every two packets (M -> S, IFPS, S->M(p1), IFPS, S->M(p2), IFPS, S->M(p3))?

or there it is like (M -> S, IFPS, S->M(p1), IFPS, M -> S, IFPS, S->M(p2), IFPS,M -> S, IFPS, S->M(p3), IFPS)?

Upvotes: 1

Views: 119

Answers (1)

Youssif Saeed
Youssif Saeed

Reputation: 13285

In Bluetooth Low Energy, every packet in a connection is acknowledged. This is mentioned in the Bluetooth Specification, v5.2, Vol 1, Part A, Section 3.1.3.2 (LE reliability):

Like BR/EDR, in poor RF environments, the LE system should be considered inherently unreliable. To counteract this, the system provides levels of protection at each layer. The LL packet uses a 24-bit cyclic redundancy error check (CRC) to cover the contents of the packet payload. If the CRC verification fails on the packet payload, the packet is not acknowledged by the receiver and the packet gets retransmitted by the sender.

So if the choice is between one of the two examples you provided, the more accurate one would be:-

(M -> S, IFPS, S->M(p1), IFPS, M -> S, IFPS, S->M(p2), IFPS,M -> S, IFPS, S->M(p3), IFPS)

However, it's not as clear cut as this because most of this happens under the hood in the baseband layer and there are other things to consider (e.g. number of packets per connection interval). If you haven't seen them already, have a look at the following links to get a better picture of how throughput is measured in BLE:-

Upvotes: 0

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