diff --git a/bluetooth/ranging/aidl/aidl_api/android.hardware.bluetooth.ranging/current/android/hardware/bluetooth/ranging/StepTonePct.aidl b/bluetooth/ranging/aidl/aidl_api/android.hardware.bluetooth.ranging/current/android/hardware/bluetooth/ranging/StepTonePct.aidl
index a51ba37..4125748 100644
--- a/bluetooth/ranging/aidl/aidl_api/android.hardware.bluetooth.ranging/current/android/hardware/bluetooth/ranging/StepTonePct.aidl
+++ b/bluetooth/ranging/aidl/aidl_api/android.hardware.bluetooth.ranging/current/android/hardware/bluetooth/ranging/StepTonePct.aidl
@@ -36,6 +36,7 @@
 parcelable StepTonePct {
   List<android.hardware.bluetooth.ranging.ComplexNumber> tonePcts;
   byte[] toneQualityIndicator;
+  byte toneExtensionAntennaIndex;
   const int TONE_QUALITY_GOOD = 0;
   const int TONE_QUALITY_MEDIUM = 1;
   const int TONE_QUALITY_LOW = 2;
@@ -44,4 +45,9 @@
   const int EXTENSION_SLOT_TONE_NOT_EXPECTED_TO_BE_PRESENT = 1;
   const int EXTENSION_SLOT_TONE_EXPECTED_TO_BE_PRESENT = 2;
   const int EXTENSION_SLOT_SHIFT_AMOUNT = 4;
+  const byte TONE_EXTENSION_ANTENNA_1 = 0x0;
+  const byte TONE_EXTENSION_ANTENNA_2 = 0x1;
+  const byte TONE_EXTENSION_ANTENNA_3 = 0x2;
+  const byte TONE_EXTENSION_ANTENNA_4 = 0x3;
+  const byte TONE_EXTENSION_UNUSED = 0xFFu8;
 }
diff --git a/bluetooth/ranging/aidl/android/hardware/bluetooth/ranging/StepTonePct.aidl b/bluetooth/ranging/aidl/android/hardware/bluetooth/ranging/StepTonePct.aidl
index 99c6d65..4650861 100644
--- a/bluetooth/ranging/aidl/android/hardware/bluetooth/ranging/StepTonePct.aidl
+++ b/bluetooth/ranging/aidl/android/hardware/bluetooth/ranging/StepTonePct.aidl
@@ -23,6 +23,10 @@
  */
 @VintfStability
 parcelable StepTonePct {
+    /**
+     * PCT measured from mode-2 or mode-3 steps
+     * (in ascending order of antenna position with tone extension data at the end).
+     */
     List<ComplexNumber> tonePcts;
     const int TONE_QUALITY_GOOD = 0;
     const int TONE_QUALITY_MEDIUM = 1;
@@ -52,4 +56,20 @@
      * See: https://bluetooth.com/specifications/specs/channel-sounding-cr-pr/
      */
     byte[] toneQualityIndicator;
+
+    const byte TONE_EXTENSION_ANTENNA_1 = 0x0;
+    const byte TONE_EXTENSION_ANTENNA_2 = 0x1;
+    const byte TONE_EXTENSION_ANTENNA_3 = 0x2;
+    const byte TONE_EXTENSION_ANTENNA_4 = 0x3;
+    const byte TONE_EXTENSION_UNUSED = 0xFFu8;
+    /**
+     * Tone Extension Antenna Index indicates the Antenna position used in tone extension slot
+     *
+     * 0x00 = A1
+     * 0x01 = A2
+     * 0x02 = A3
+     * 0x03 = A4
+     * 0xFF = Tone extension not used
+     */
+    byte toneExtensionAntennaIndex;
 }