WS: Restart auto CCA threshold after discovery (ARMmbed#2435)

Author: Jarkko Paso

source/6LoWPAN/ws/ws_bootstrap.c

@@ -1639,6 +1639,10 @@ bool ws_bootstrap_validate_channel_function(ws_us_ie_t *ws_us, ws_bs_ie_t *ws_bs
 
 static void ws_bootstrap_asynch_ind(struct protocol_interface_info_entry *cur, const struct mcps_data_ind_s *data, const struct mcps_data_ie_list *ie_ext, uint8_t message_type)
 {
+    // Store weakest heard packet RSSI
+    if (cur->ws_info->weakest_received_rssi > data->signal_dbm) {
+        cur->ws_info->weakest_received_rssi = data->signal_dbm;
+    }
 
     if (data->SrcAddrMode != MAC_ADDR_MODE_64_BIT) {
         // Not from long address
@@ -2654,6 +2658,7 @@ static void ws_bootstrap_start_discovery(protocol_interface_info_entry_t *cur)
     cur->nwk_nd_re_scan_count = 0;
     cur->ws_info->configuration_learned = false;
     cur->ws_info->pan_timeout_timer = 0;
+    cur->ws_info->weakest_received_rssi = 0;
 
     // Clear learned neighbours
     ws_bootstrap_neighbor_list_clean(cur);
@@ -3415,6 +3420,11 @@ void ws_bootstrap_state_machine(protocol_interface_info_entry_t *cur)
             cur->ws_info->trickle_pcs_running = false;
             cur->ws_info->trickle_pc_consistency_block_period = 0;
             ws_fhss_configure(cur, false);
+            int8_t new_default = cur->ws_info->weakest_received_rssi - 1;
+            if ((new_default < CCA_DEFAULT_DBM) && (new_default >= CCA_LOW_LIMIT) && (new_default <= CCA_HIGH_LIMIT)) {
+                // Restart automatic CCA threshold using weakest received RSSI as new default
+                mac_helper_start_auto_cca_threshold(cur->id, cur->ws_info->hopping_schdule.number_of_channels, cur->ws_info->weakest_received_rssi - 1, CCA_HIGH_LIMIT, CCA_LOW_LIMIT);
+            }
             ws_bootstrap_start_authentication(cur);
             break;
         case ER_RPL_SCAN:

source/6LoWPAN/ws/ws_common.h

@@ -84,6 +84,7 @@ typedef struct ws_info_s {
     uint8_t pas_requests; // Amount of PAN solicits sent
     uint8_t eapol_tx_index;
     uint8_t device_min_sens; // Device min sensitivity set by the application
+    int8_t weakest_received_rssi; // Weakest received signal (dBm)
     parent_info_t parent_info[WS_PARENT_LIST_SIZE];
     parent_info_list_t parent_list_free;
     parent_info_list_t parent_list_reserved;

source/6LoWPAN/ws/ws_common_defines.h

@@ -332,7 +332,7 @@ typedef struct ws_bs_ie {
 /*
  * Automatic CCA threshold: default threshold and range in dBm.
  */
-#define CCA_DEFAULT_DBM -100
+#define CCA_DEFAULT_DBM -60
 #define CCA_HIGH_LIMIT  -60
 #define CCA_LOW_LIMIT   -100