diff --git a/components/esp8266/include/esp_wifi_types.h b/components/esp8266/include/esp_wifi_types.h
index 10a61141..72b24fc6 100755
--- a/components/esp8266/include/esp_wifi_types.h
+++ b/components/esp8266/include/esp_wifi_types.h
@@ -303,14 +303,14 @@ typedef struct {
     unsigned is_group: 1;     /**< usually not used */
     unsigned : 1;             /**< reserve */
     unsigned sig_mode: 2;     /**< 0:is not 11n packet; 1:is 11n packet */
-    unsigned legacy_length: 12; /**< usually not used */
+    unsigned legacy_length: 12; /**< Length of 11bg mode packet */
     unsigned damatch0: 1;     /**< usually not used */
     unsigned damatch1: 1;     /**< usually not used */
     unsigned bssidmatch0: 1;  /**< usually not used */
     unsigned bssidmatch1: 1;  /**< usually not used */
     unsigned mcs: 7;          /**< if is 11n packet, shows the modulation(range from 0 to 76) */
     unsigned cwb: 1;          /**< if is 11n packet, shows if is HT40 packet or not */
-    unsigned HT_length: 16;            /**< reserve */
+    unsigned HT_length: 16;   /**< Length of 11n mode packet */
     unsigned smoothing: 1;    /**< reserve */
     unsigned not_sounding: 1; /**< reserve */
     unsigned : 1;             /**< reserve */
@@ -329,7 +329,7 @@ typedef struct {
  */
 typedef struct {
     wifi_pkt_rx_ctrl_t rx_ctrl; /**< metadata header */
-    uint8_t payload[0];       /**< Data or management payload. Length of payload is described by rx_ctrl.sig_len. Type of content determined by packet type argument of callback. */
+    uint8_t payload[0];       /**< Data or management payload. Length of payload is described by rx_ctrl.legacy_length or rx_ctrl.HT_length. Type of content determined by packet type argument of callback. */
 } wifi_promiscuous_pkt_t;
 
 /**