We've been developing an iOS app in Swift for several years that run on iPad tablets in which our proprietary device emits EEG signals via BLE to the app running on the iPad tablet.
The device emits the data as BLE notification messages in which the MTU is set to the maximum size that is allowed between our device and the iPad.
Our device when communicating with the app running on a 10th generation iPad running iOS 18.5 it takes less than 200ms to transmit an interval of EEG signals which occurs at 500ms.
Under the same conditions same version of iOS & app and the same device but using an iPad 11th generation, it takes anywhere from 800ms to 1.1 seconds (4x to 5x) to transmit an interval.
Our device transmits the EEG ****** using several ATT notification messages using the maximum MTU size.
We are perplexed about such a huge step down in performance when running on the iPad 11th generation tablets.
iPad generation Chipset Firmware
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10th BCM_4387 22.5.614.3457
11th SRS_7923 HCI Rev. 2504 sub. 5003
We know that the 10th generation iPad used chipset manufactured by Broadcom. Whereas the iPad 11th generation that we've received uses a SRS chipset in which I'm unfamiliar with that chipset's manufacturer.
We question if this performance degradation is due from the chipset manufacturer, the firmware revision when using attribute notifications messages over BLE in such a context.
Using PacketLogger as to log the communication between the iPad tablets and our device and after analysis we haven't found anything that identifies difference in configuration settings that are exchanged between our device and iPad tablets that account for this performance degradation.
Fortunately, our device is designed to work in complex environments & contexts and thus it has mechanisms accounting for transmission delays and interferences.
I'd appreciate if any other Apple Developer or Apple staff is aware of the degradation when transmitting BLE attribute notification messages with the newer Apple devices using this series of chipset.
If so, then:
- Are there any recommendations of solutions to improve this latency?
- Is this is being addressed for iPad 11th generation tablets?
Regards,
Steven Belbin Principal Developer at NeuroServo Inc.