BLE itself has no baud rate interface, just packets. Unless you're using one of those HM10/HC08 BLE-to-serial adapter things, which would ferry bytes to/from the UART from/to your Android device in blocks of up-to-20 bytes. But note the bytes-per-second limits table in the datasheet, it was quite (s)low (relative to 115200 baud).
i am using "DSD TECH HM-10 Bluetooth 4.0 BLE iBeacon UART Modul mit 4 PIN Base Board für Arduino UNO R3 Mega 2560 Nano"
i will see what happens if me change the baud rate in the arduino ide Serial.begin(115200)
If its based off of the Nordic nRF Chip, you can download the UART example project, and purchase a SEGGER kit, then modify the firmware to increase the maximum transfer width. I have mine at the maximum theoretical size of 128 bytes per transfer.
arduino via bluetooth to phone is a game of pure chance.
... software serial need a lower baud rate. 38400 seems ok.
best choice is the hardware serial but uno have only one that used the usb to pc too.