I have noticed some significant changes to iOS bluetooth low energy connection interval and allowed packets per interval.
I'm using a maker ble device to transmit sensor data at high rates, quick connect and disconnect because the user comes in and out of range frequently. I can request connection interval updates peripheral side and have done some timing to see how many packets are transmitted per interval.
iOS 8.1 seems to allow connection interval of 18.75 ms with 7 packets per interval.
iOS 8.3 seems to allow connection interval of 15.0 ms with 3 packets per interval.
I want to transfer 100 notification packets, with the above info my transfer is roughly cut in half!!
iOS 8.1 takes approx .267 seconds (100/7*18.75 ms)
iOS 8.3 takes approx .5 seconds (100/3*15 ms)
I watched a protocol trace with my Apple Watch connecting and it showed a connection interval of 30 ms and during high data transfers as many as 7 notification packets per interval (Handoff in action!)
Anyone else requesting a connection interval update and seeing decreased performance as of 8.3? Any better transfer times for different connection intervals?