replace ETX calculation for Wi-SUN

Create new function to calculate ETX for Wi-SUN
Calculate parent candidate set using signal strength

Author: Mika Tervonen

source/6LoWPAN/ws/ws_bootstrap.c

@@ -219,6 +219,47 @@ static int8_t ws_enable_fhss(protocol_interface_info_entry_t *cur)
     cur->ws_info->fhss_api = fhss_api;
     return 0;
 }
+/* \return 0x0100 to 0xFFFF ETX value (8 bit fraction)
+ * \return 0xFFFF address not associated
+ * \return 0x0000 address unknown or other error
+ * \return 0x0001 no ETX statistics on this interface
+ */
+uint16_t ws_etx_read(protocol_interface_info_entry_t *interface, addrtype_t addr_type, const uint8_t *addr_ptr)
+{
+
+    uint16_t etx;
+    if (!addr_ptr || !interface) {
+        return 0;
+    }
+
+    uint8_t attribute_index;
+
+    mac_neighbor_table_entry_t *mac_neighbor = mac_neighbor_table_address_discover(mac_neighbor_info(interface), addr_ptr + PAN_ID_LEN, addr_type);
+    if (!mac_neighbor) {
+        return 0xffff;
+    }
+    attribute_index = mac_neighbor->index;
+    ws_neighbor_class_entry_t *ws_neighbour = ws_neighbor_class_entry_get(&interface->ws_info->neighbor_storage, attribute_index);
+
+    if (!ws_neighbour ||
+        !ws_neighbour->candidate_parent) {
+        // if RSL value is not good enough candidate parent flag is removed and device not accepted as parent
+        //tr_debug("ws_etx_read not valid parent");
+        return 0xffff;
+    }
+
+    etx = etx_local_etx_read(interface->id,attribute_index);
+    if (etx == 0) {
+        return 0xffff;
+    }
+    if (etx > 0x800) {
+        // Wi-SUN section 6.2.3.1.6.1 says ETX can only be maximum of 1024 (8*128) in RPL units, ie 8.0.
+        etx =  0x800;
+    }
+
+    //tr_debug("ws_etx_read etx:%d", etx);
+    return etx;
+}
 
 static int8_t ws_bootstrap_up(protocol_interface_info_entry_t *cur)
 {
@@ -891,6 +932,7 @@ int ws_bootstrap_init(int8_t interface_id, net_6lowpan_mode_e bootstrap_mode)
     cur->if_up = ws_bootstrap_up;
     cur->if_down = ws_bootstrap_down;
     cur->ws_info->neighbor_storage = neigh_info;
+    cur->etx_read_override = ws_etx_read;
 
     ws_bootstrap_configuration_reset(cur);
     addr_notification_register(ws_bootstrap_address_notification_cb);

source/6LoWPAN/ws/ws_common_defines.h

@@ -185,6 +185,15 @@ typedef struct ws_bs_ie {
 #define WS_NEIGHBOR_LINK_TIMEOUT 240
 #define WS_NEIGHBOR_NUD_TIMEOUT WS_NEIGHBOR_LINK_TIMEOUT / 2
 
+/*
+ * Threshold (referenced to DEVICE_MIN_SENS) above which a neighbor node may be considered for inclusion into candidate parent set
+ */
+#define CAND_PARENT_THRESHOLD 10
+/*
+ * Hysteresis factor to be applied to CAND_PARENT_THRESHOLD when admitting or dropping nodes from the candidate parent set.
+ */
+#define CAND_PARENT_HYSTERISIS 3
+
 /*
  * value when send the first RPL DIS in 100ms ticks. Value is randomized between timeout/2 - timeout
  */
@@ -194,5 +203,4 @@ typedef struct ws_bs_ie {
  */
 #define WS_RPL_DIS_TIMEOUT 1800
 
-
 #endif /* WS_COMMON_DEFINES_H_ */

source/6LoWPAN/ws/ws_neighbor_class.c

@@ -123,24 +123,43 @@ uint8_t ws_neighbor_class_rssi_from_dbm_calculate( int8_t dbm_heard)
     return dbm_heard - DEVICE_MIN_SENS;
 }
 
+static void ws_neighbor_class_parent_set_analyze(ws_neighbor_class_entry_t *ws_neighbor)
+{
+    if (ws_neighbor->rsl_in == RSL_UNITITIALIZED ||
+        ws_neighbor->rsl_out == RSL_UNITITIALIZED) {
+        ws_neighbor->candidate_parent = false;
+        return;
+    }
+
+    if (ws_neighbor_class_rsl_in_get(ws_neighbor) < (CAND_PARENT_THRESHOLD - CAND_PARENT_HYSTERISIS) &&
+        ws_neighbor_class_rsl_out_get(ws_neighbor) < (CAND_PARENT_THRESHOLD - CAND_PARENT_HYSTERISIS)) {
+        ws_neighbor->candidate_parent = false;
+    }
+
+    if (ws_neighbor_class_rsl_in_get(ws_neighbor) > (CAND_PARENT_THRESHOLD + CAND_PARENT_HYSTERISIS) &&
+        ws_neighbor_class_rsl_out_get(ws_neighbor) > (CAND_PARENT_THRESHOLD + CAND_PARENT_HYSTERISIS)) {
+        ws_neighbor->candidate_parent = true;
+    }
+}
+
 void ws_neighbor_class_rsl_in_calculate(ws_neighbor_class_entry_t *ws_neighbor, int8_t dbm_heard)
 {
     uint8_t rssi = ws_neighbor_class_rssi_from_dbm_calculate(dbm_heard);
     if (ws_neighbor->rsl_in == RSL_UNITITIALIZED) {
         ws_neighbor->rsl_in = rssi << WS_RSL_SCALING;
-        return;
     }
     ws_neighbor->rsl_in = ws_neighbor->rsl_in + rssi - (ws_neighbor->rsl_in >> WS_RSL_SCALING);
+    ws_neighbor_class_parent_set_analyze(ws_neighbor);
     return;
 }
 
 void ws_neighbor_class_rsl_out_calculate(ws_neighbor_class_entry_t *ws_neighbor, uint8_t rsl_reported)
 {
     if (ws_neighbor->rsl_out == RSL_UNITITIALIZED) {
         ws_neighbor->rsl_out = rsl_reported << WS_RSL_SCALING;
-        return;
     }
     ws_neighbor->rsl_out = ws_neighbor->rsl_out + rsl_reported - (ws_neighbor->rsl_out >> WS_RSL_SCALING);
+    ws_neighbor_class_parent_set_analyze(ws_neighbor);
     return;
 }
 

source/6LoWPAN/ws/ws_neighbor_class.h

@@ -25,6 +25,7 @@ typedef struct ws_neighbor_class_entry {
     fhss_ws_neighbor_timing_info_t   fhss_data;
     uint16_t rsl_in;                                       /*!< RSL EWMA heard from neighbour*/
     uint16_t rsl_out;                                      /*!< RSL EWMA heard by neighbour*/
+    bool candidate_parent:1;
 } ws_neighbor_class_entry_t;
 
 /**

source/NWK_INTERFACE/Include/protocol.h

@@ -342,7 +342,6 @@ typedef void beacon_indication_cb(int8_t if_id, const mlme_beacon_ind_t* conf);
 typedef void comm_status_indication_cb(int8_t if_id, const mlme_comm_status_t* status);
 
 
-
 struct protocol_interface_info_entry {
     beacon_indication_cb *beacon_cb;
     scan_confirm_cb *scan_cb;
@@ -476,6 +475,7 @@ struct protocol_interface_info_entry {
     uint8_t (*if_llao_parse)(struct protocol_interface_info_entry *cur, const uint8_t *opt_in, sockaddr_t *ll_addr_out);
     uint8_t (*if_llao_write)(struct protocol_interface_info_entry *cur, uint8_t *opt_out, uint8_t opt_type, bool must, const uint8_t *ip_addr);
     void (*mac_security_key_usage_update_cb)(struct protocol_interface_info_entry *cur, const struct mlme_security_s *security_params);
+    uint16_t (*etx_read_override)(struct protocol_interface_info_entry *cur, addrtype_t addr_type, const uint8_t *addr_ptr);
 };
 
 typedef NS_LIST_HEAD(protocol_interface_info_entry_t, link) protocol_interface_list_t;

source/Service_Libs/etx/etx.c

@@ -188,6 +188,11 @@ uint16_t etx_read(int8_t interface_id, addrtype_t addr_type, const uint8_t *addr
         return 0;
     }
 
+    if (interface->etx_read_override) {
+        // Interface has modified ETX calculation
+        return interface->etx_read_override(interface, addr_type, addr_ptr);
+    }
+
     uint8_t attribute_index;
     if (interface->nwk_id == IF_IPV6) {
         return 1;
@@ -242,6 +247,25 @@ uint16_t etx_local_incoming_idr_read(int8_t interface_id, uint8_t attribute_inde
     return local_incoming_idr;
 }
 
+/**
+ * \brief A function to read local incoming IDR value
+ *
+ *  Returns local incoming IDR value for an address
+ *
+ * \param mac64_addr_ptr long MAC address
+ *
+ * \return 0x0100 to 0xFFFF incoming IDR value (8 bit fraction)
+ * \return 0x0000 address unknown
+ */
+uint16_t etx_local_etx_read(int8_t interface_id, uint8_t attribute_index)
+{
+    etx_storage_t * entry = etx_storage_entry_get(interface_id, attribute_index);
+    if (!entry) {
+        return 0;
+    }
+    return etx_current_calc(entry->etx, entry->accumulated_failures) >> 4;
+}
+
 /**
  * \brief A function to calculate current ETX
  *

source/Service_Libs/etx/etx.h

@@ -93,6 +93,18 @@ uint16_t etx_read(int8_t interface_id, addrtype_t addr_type, const uint8_t *addr
  */
 uint16_t etx_local_incoming_idr_read(int8_t interface_id, uint8_t attribute_index);
 
+/**
+ * \brief A function to read local ETXvalue
+ *
+ *  Returns local ETX value for an address
+ *
+ * \param mac64_addr_ptr long MAC address
+ *
+ * \return 0x0100 to 0xFFFF ETX value (8 bit fraction)
+ * \return 0x0000 address unknown
+ */
+uint16_t etx_local_etx_read(int8_t interface_id, uint8_t attribute_index);
+
 /**
  * \brief A function to update ETX value based on LQI and dBm
  *