Modify NUD operation propability.

Change-Id: I78d478709b6a85cfcf25fe60cd390bbbbd98117c

Author: Juha Heiskanen

source/6LoWPAN/ws/ws_bootstrap.c

@@ -990,16 +990,33 @@ static bool ws_neighbor_entry_nud_notify(mac_neighbor_table_entry_t *entry_ptr,
     }
 
     if (time_from_start > WS_NEIGHBOR_NUD_TIMEOUT) {
-        //Take Random from 1-1.5 time WS_NEIGHBOR_NUD_TIMEOUT
-        uint32_t compare_random = randLIB_randomise_base(WS_NEIGHBOR_NUD_TIMEOUT, 0x8000, 0xC000);
-        if (time_from_start > compare_random) {
+
+        if (time_from_start > WS_NEIGHBOR_NUD_TIMEOUT * 1.5) {
             activate_nud = true;
+        } else {
+            uint16_t switch_prob = randLIB_get_random_in_range(0, WS_NUD_RANDOM_SAMPLE_LENGTH -1);
+            //Take Random from time WS_NEIGHBOR_NUD_TIMEOUT - WS_NEIGHBOR_NUD_TIMEOUT*1.5
+            if (switch_prob < WS_NUD_RANDOM_COMPARE) {
+                activate_nud = true;
+            }
         }
-    } else if (etx_entry->etx_samples < 3) {
-        uint32_t compare_random = randLIB_get_random_in_range(1 << etx_entry->etx_samples, 8 << etx_entry->etx_samples);
-        if (time_from_start > compare_random) {
-            tr_debug("Link Probe test %u with jitter", compare_random);
+    } else if (etx_entry->etx_samples < WS_NEIGBOR_ETX_SAMPLE_MAX) {
+        //Take Random number for trig a prope.
+        //ETX Sample 0: random 1-8
+        //ETX Sample 1: random 2-16
+        //ETX Sample 2: random 4-32
+        uint32_t probe_period = WS_PROBE_INIT_BASE_SECONDS << etx_entry->etx_samples;
+        uint32_t time_block = 1 << etx_entry->etx_samples;
+        if (time_from_start >= probe_period) {
+            tr_debug("Link Probe test %u Sample trig", etx_entry->etx_samples);
             activate_nud = true;
+        } else if (time_from_start > time_block) {
+            uint16_t switch_prob = randLIB_get_random_in_range(0, probe_period -1);
+            //Take Random from time WS_NEIGHBOR_NUD_TIMEOUT - WS_NEIGHBOR_NUD_TIMEOUT*1.5
+            if (switch_prob < 2) {
+                tr_debug("Link Probe test with jitter %u, sample %u", time_from_start, etx_entry->etx_samples);
+                activate_nud = true;
+            }
         }
     }
 

source/6LoWPAN/ws/ws_common_defines.h

@@ -185,6 +185,16 @@ typedef struct ws_bs_ie {
 #define WS_NEIGHBOR_LINK_TIMEOUT 2200
 #define WS_NEIGHBOR_NUD_TIMEOUT WS_NEIGHBOR_LINK_TIMEOUT / 2
 
+#define WS_NEIGBOR_ETX_SAMPLE_MAX 3
+
+#define WS_PROBE_INIT_BASE_SECONDS 8
+
+#define WS_NUD_RAND_PROBABILITY 10
+
+#define WS_NUD_RANDOM_SAMPLE_LENGTH WS_NEIGHBOR_NUD_TIMEOUT / 2
+
+#define WS_NUD_RANDOM_COMPARE (WS_NUD_RAND_PROBABILITY*WS_NUD_RANDOM_SAMPLE_LENGTH) / 100
+
 /*
  * Threshold (referenced to DEVICE_MIN_SENS) above which a neighbor node may be considered for inclusion into candidate parent set
  */