diff --git a/nanostack/platform/arm_hal_phy.h b/nanostack/platform/arm_hal_phy.h
index 98a9768252f..d0d3dba41c3 100644
--- a/nanostack/platform/arm_hal_phy.h
+++ b/nanostack/platform/arm_hal_phy.h
@@ -62,8 +62,8 @@ typedef enum {
     PHY_EXTENSION_READ_TX_FINNISH_TIME, /**< Read the time of last finished TX symbol based on global time stamp. */
     PHY_EXTENSION_DYNAMIC_RF_SUPPORTED, /**< Read status for support Radio driver support for set TX time, CCA and Timestamp read. Also PHY_LINK_CCA_PREPARE tx status must be supported also*/
     PHY_EXTENSION_GET_TIMESTAMP, /**<  Read 32-bit constant monotonic time stamp in us */
-    PHY_EXTENSION_SET_CSMA_PARAMETERS, /**< CSMA parameter's: Include 32-bit backoff time in us and CCA mode used after timeout CCA is boolean true do normal CCA and false start TX direct*/
-    PHY_EXTENSION_GET_SYMBOLS_IN_SECOND, /**<  Read Symbols per seconds which will help to convert symbol time to real time  */
+    PHY_EXTENSION_SET_CSMA_PARAMETERS, /**< CSMA parameter's are given by phy_csma_params_t structure remember type cast uint8_t pointer to structure type*/
+    PHY_EXTENSION_GET_SYMBOLS_PER_SECOND, /**<  Read Symbols per seconds which will help to convert symbol time to real time  */
 } phy_extension_type_e;
 
 /** Address types */
@@ -118,6 +118,12 @@ typedef struct phy_signal_info_s {
     uint16_t result;                /**< Resulting signal information. */
 } phy_signal_info_s;
 
+/** CSMA-CA parameters */
+typedef struct phy_csma_params {
+    uint32_t symbol_backoff_time;    /**< CSMA Backoff symbol time before start CCA & TX. */
+    bool cca_enabled;                /**< True will affect CCA check false start TX direct after backoff */
+} phy_csma_params_t;
+
 /** PHY modulation scheme */
 typedef enum phy_modulation_e
 {