iPhone 4S - BLE data transfer speed

问题:

I've been tinkering around with the BLE (Bluetooth Low Energy) connectivity classes quiet a bit lately and haven't been able to make it transfer data any faster than 1KB / 5 seconds. I believe, in the documentation, it says the max speed is 60 bytes per 20 milliseconds. With data transfer and counting the Ack transfer after each set of packets, I believe we should be able to go as fast as 1.5KB per second. So my code is around 7-8 times slower than it should be.

I'm just wondering if anyone has been able to do data transfer in BLE as fast as the documentation says it should be able to do. What sort of speed are you getting if faster than mine?

Thanks a lot

回答1:

see at the guidlines of apple and you will see that a connection update request is required to speed up your connection.

https://developer.apple.com/hardwaredrivers/BluetoothDesignGuidelines.pdf

I have min=20ms max 40 ms

I hope I could help

Roman

回答2:

If you are able to use higher MTU size (negotiated by the iOS) then you would be able to increase the bandwidth even more, because there is a 4 byte L2CAP header and a 3 byte ATT header that wouldn't be transmitted more than in one packet.

If you are able to transmit 6 packets pr connection interval, then you would be able to put in 35 byte extra per connection interval (the 7 byte header would still be there for the first packet) The MTU size could also be split over several connection intervals, increasing the throughput with 7 more bytes pr connection interval. (Just takes longer time to assemble the packet again.) The max MTU size allowed by ATT is 515 bytes (Max size of att is 512 bytes + 3 byte header for opcode + handle)