Maximise sampling rate via Bluetooth Serial

[willpowell]

Hi everyone,
I need to transmit 16bit unsigned integers from an external ADC wirelessly, with the maximum sample rate possible.

I have configured the arduino nano 33 iot to allow for standard bluetooth using this method. This essentially means I have connected through UART to the NINA W102 (based on the ESP32 module).

I have created a test code (ignoring the ADC for now) and recorded the Serial speeds through the virtual COM port.

unsigned long startTime = 0;

void setup() {

     pinMode(NINA_RESETN, OUTPUT);  
     pinMode(LED_BUILTIN, OUTPUT);        
     digitalWrite(NINA_RESETN, HIGH);
     Serial.begin(115200);
     SerialNina.begin(115200);
     delay(20000); // wait for 20 seconds to allow user to setup bluetooth on PC
     startTime = millis();
}

void loop() {
  //for 10 seconds, print 16 bit numbers as fast as possible
  while(startTime + 10000 > millis()){
    for(uint16_t i=0; i<30;i++){
      SerialNina.println(i);
      }
  }
}

I am getting around 2.2kHz currently through the Bluetooth Serial through COM, which is not enough. I have also tried normal Serialprint() and received around 10kHz from the wired COM port, which is more acceptable.

Any ideas why there is such a difference since bluetooth 4.0 should be able to transmit much faster? Do I need to use an encoding method like Packet Serial or add a buffer? Also what is the most efficient way of sending data from multiple channels?

I have also used the WiFi functionality of the nano 33 iot, but receiving around 100Hz using a local server on my PC.

Any advice greatly appreciated, this project is incredibly important to me.
Thanks in advance,
Will