improved capture effect support in mrm: capture effect is effective if the latter transmission is stronger and no later than half the preamble

tools/cooja/apps/mrm/java/se/sics/mrm/ChannelModel.java

@@ -135,7 +135,10 @@ public class ChannelModel {
     rt_reflec_coefficient,
     rt_diffr_coefficient,
     rt_scatt_coefficient,
-    obstacle_attenuation;
+    obstacle_attenuation,
+    captureEffect,
+    captureEffectPreambleDuration,
+    captureEffectSignalTreshold;
 
     public static Object getDefaultValue(Parameter p) {
       switch (p) {
@@ -187,6 +190,12 @@ public class ChannelModel {
         return new Double(-20);
       case obstacle_attenuation:
         return new Double(-3);
+      case captureEffect:
+        return true;
+      case captureEffectPreambleDuration:
+        return (double) (1000*1000*4*0.5*8/250000); /* 2 bytes, 250kbit/s, us */
+      case captureEffectSignalTreshold:
+        return (double) 3; /* dB, according to previous 802.15.4 studies */
       }
       throw new RuntimeException("Unknown default value: " + p);
     }
@@ -235,6 +244,12 @@ public class ChannelModel {
         return rt_scatt_coefficient;
       } else if (name.equals("obstacle_attenuation")) {
         return obstacle_attenuation;
+      } else if (name.equals("captureEffect")) {
+        return captureEffect;
+      } else if (name.equals("captureEffectPreambleDuration")) {
+        return captureEffectPreambleDuration;
+      } else if (name.equals("captureEffectSignalTreshold")) {
+        return captureEffectSignalTreshold;
       }
       return null;
     }
@@ -263,6 +278,9 @@ public class ChannelModel {
       case rt_reflec_coefficient: return "Reflection coefficient (dB)";
       case rt_diffr_coefficient: return "Diffraction coefficient (dB)";
       case obstacle_attenuation: return "Obstacle attenuation (dB/m)";
+      case captureEffect: return "Use Capture Effect";
+      case captureEffectPreambleDuration: return "Capture effect preamble (us)";
+      case captureEffectSignalTreshold: return "Capture effect threshold (dB)";
       }
       throw new RuntimeException("Unknown decrption: " + p);
     }

tools/cooja/apps/mrm/java/se/sics/mrm/FormulaViewer.java

@@ -151,6 +151,27 @@ public class FormulaViewer extends se.sics.cooja.VisPlugin {
         channelModel.getParameterDoubleValue(Parameter.frequency)
     );
 
+    addBooleanParameter(
+        Parameter.captureEffect,
+        Parameter.getDescription(Parameter.captureEffect),
+        collapsableArea,
+        channelModel.getParameterBooleanValue(Parameter.captureEffect)
+    );
+
+    addDoubleParameter(
+        Parameter.captureEffectPreambleDuration,
+        Parameter.getDescription(Parameter.captureEffectPreambleDuration),
+        collapsableArea,
+        channelModel.getParameterDoubleValue(Parameter.captureEffectPreambleDuration)
+    );
+    
+    addDoubleParameter(
+        Parameter.captureEffectSignalTreshold,
+        Parameter.getDescription(Parameter.captureEffectSignalTreshold),
+        collapsableArea,
+        channelModel.getParameterDoubleValue(Parameter.captureEffectSignalTreshold)
+    );
+    
     // Transmitter parameters
     collapsableArea = createCollapsableArea("Transmitter parameters", allComponents);
     areaTransmitter = collapsableArea;

tools/cooja/apps/mrm/java/se/sics/mrm/MRM.java

@@ -80,7 +80,12 @@ public class MRM extends AbstractRadioMedium {
 
   public final static boolean WITH_NOISE = true; /* NoiseSourceRadio */
   public final static boolean WITH_DIRECTIONAL = true; /* DirectionalAntennaRadio */
-  public final static boolean WITH_CAPTURE_EFFECT = true;
+
+  private Observer channelModelObserver = null;
+
+  private boolean WITH_CAPTURE_EFFECT;
+  private double CAPTURE_EFFECT_THRESHOLD;
+  private double CAPTURE_EFFECT_PREAMBLE_DURATION;
   
   private Simulation sim;
   private Random random = null;
@@ -101,6 +106,18 @@ public class MRM extends AbstractRadioMedium {
     random = simulation.getRandomGenerator();
     currentChannelModel = new ChannelModel(sim);
     
+    WITH_CAPTURE_EFFECT = currentChannelModel.getParameterBooleanValue(ChannelModel.Parameter.captureEffect);
+    CAPTURE_EFFECT_THRESHOLD = currentChannelModel.getParameterDoubleValue(ChannelModel.Parameter.captureEffectSignalTreshold);
+    CAPTURE_EFFECT_PREAMBLE_DURATION = currentChannelModel.getParameterDoubleValue(ChannelModel.Parameter.captureEffectPreambleDuration);
+   
+    currentChannelModel.addSettingsObserver(channelModelObserver = new Observer() {
+      public void update(Observable o, Object arg) {
+        WITH_CAPTURE_EFFECT = currentChannelModel.getParameterBooleanValue(ChannelModel.Parameter.captureEffect);
+        CAPTURE_EFFECT_THRESHOLD = currentChannelModel.getParameterDoubleValue(ChannelModel.Parameter.captureEffectSignalTreshold);
+        CAPTURE_EFFECT_PREAMBLE_DURATION = currentChannelModel.getParameterDoubleValue(ChannelModel.Parameter.captureEffectPreambleDuration);
+      }
+    });
+    
     /* Register plugins */
     sim.getGUI().registerPlugin(AreaViewer.class);
     sim.getGUI().registerPlugin(FormulaViewer.class);
@@ -114,6 +131,8 @@ public class MRM extends AbstractRadioMedium {
     sim.getGUI().unregisterPlugin(AreaViewer.class);
     sim.getGUI().unregisterPlugin(FormulaViewer.class);
     Visualizer.unregisterVisualizerSkin(MRMVisualizerSkin.class);
+
+    currentChannelModel.deleteSettingsObserver(channelModelObserver);
   }
   
   private NoiseLevelListener noiseListener = new NoiseLevelListener() {
@@ -177,22 +196,26 @@ public class MRM extends AbstractRadioMedium {
           newConnection.addInterfered(recv);
           recv.interfereAnyReception();
         } else if (recv.isInterfered()) {
-          /* Was interfered: keep interfering */
+          if (WITH_CAPTURE_EFFECT) {
-          newConnection.addInterfered(recv, recvSignalStrength);
+            /* XXX TODO This may be wrong:
+             * If the interfering signal is both weaker and the SFD has not 
+             * been received, then the stronger signal may actually be received.
+             */
+
+            /* Was interfered: keep interfering */
+            newConnection.addInterfered(recv, recvSignalStrength);
+          } else {
+            /* Was interfered: keep interfering */
+            newConnection.addInterfered(recv, recvSignalStrength);
+          }
         } else if (recv.isTransmitting()) {
           newConnection.addInterfered(recv, recvSignalStrength);
         } else if (recv.isReceiving()) {
           /* Was already receiving: start interfering.
            * Assuming no continuous preambles checking */
 
-                double currSignal = recv.getCurrentSignalStrength();
+          if (!WITH_CAPTURE_EFFECT) {
-                /* Capture effect: recv-radio is already receiving.
+            newConnection.addInterfered(recv, recvSignalStrength);
-                 * Are we strong enough to interfere? */
-                if (WITH_CAPTURE_EFFECT &&
-                                recvSignalStrength < currSignal - 3 /* config */) {
-                        /* No, we are too weak */
-                } else {
-                newConnection.addInterfered(recv, recvSignalStrength);
             recv.interfereAnyReception();
 
             /* Interfere receiver in all other active radio connections */
@@ -201,7 +224,42 @@ public class MRM extends AbstractRadioMedium {
                 conn.addInterfered(recv);
               }
             }
+          } else {
+            /* CAPTURE EFFECT */
+            double currSignal = recv.getCurrentSignalStrength();
+            /* Capture effect: recv-radio is already receiving.
+             * Are we strong enough to interfere? */
+
+            if (recvSignalStrength < currSignal - CAPTURE_EFFECT_THRESHOLD /* config */) {
+              /* No, we are too weak */
+            } else {
+              /* New signal is strong enough to either interfere with ongoing transmission,
+               * or to be received/captured */
+              long startTime = newConnection.getReceptionStartTime();
+              boolean interfering = (sim.getSimulationTime()-startTime) >= CAPTURE_EFFECT_PREAMBLE_DURATION; /* us */
+              if (interfering) {
+                newConnection.addInterfered(recv, recvSignalStrength);
+                recv.interfereAnyReception();
+
+                /* Interfere receiver in all other active radio connections */
+                for (RadioConnection conn : getActiveConnections()) {
+                  if (conn.isDestination(recv)) {
+                    conn.addInterfered(recv);
+                  }
                 }
+              } else {
+                /* XXX Warning: removing destination from other connections */
+                for (RadioConnection conn : getActiveConnections()) {
+                  if (conn.isDestination(recv)) {
+                    conn.removeDestination(recv);
+                  }
+                }
+
+                /* Success: radio starts receiving */
+                newConnection.addDestination(recv, recvSignalStrength);
+              }
+            }
+          }
 
         } else {
           /* Success: radio starts receiving */

tools/cooja/java/se/sics/cooja/RadioConnection.java

@@ -90,6 +90,15 @@ public class RadioConnection {
     return startTime;
   }
 
+  /**
+   * @return Start time of ongoing reception
+   */
+  public long getReceptionStartTime() {
+    /* TODO XXX: This may currently return the start time of an ongoing 
+     * interference. */
+    return getStartTime();
+  }
+  
   /**
    * Add (non-interfered) destination radio to connection.
    *
@@ -99,6 +108,24 @@ public class RadioConnection {
     addDestination(radio, new Long(0));
   }
   
+  /**
+   * Experimental: remove destination.
+   *
+   * @param radio Radio
+   */
+  public void removeDestination(Radio radio) {
+    int idx = allDestinations.indexOf(radio);
+    if (idx < 0) {
+      logger.fatal("Radio is not a connection destination: " + radio);
+      return;
+    }
+    
+    allDestinations.remove(idx);
+    allDestinationDelays.remove(idx);
+    destinationsNonInterfered.remove(radio);
+    onlyInterfered.remove(radio);
+  }
+
   /**
    * Add (non-interfered) destination radio to connection.
    *