worked on signal-strength-estimation

add this information to grid nodes
evaluate this information
new test-cases

sensors/radio/model/WiFiModelLogDist.h

@@ -0,0 +1,31 @@
+#ifndef WIFIMODELLOGDIST_H
+#define WIFIMODELLOGDIST_H
+
+#include "WiFiModel.h"
+#include "LogDistanceModel.h"
+
+/**
+ * signal-strength estimation using log-distance model
+ */
+class WiFiModelLogDist : public WiFiModel {
+
+private:
+
+	float txp;
+	float exp;
+
+public:
+
+	/** ctor */
+	WiFiModelLogDist(const float txp, const float exp) : txp(txp), exp(exp) {
+		;
+	}
+
+	/** get the given access-point's RSSI at the provided location */
+	float getRSSI(const LocatedAccessPoint& ap, const Point3 p) override {
+		return LogDistanceModel::distanceToRssi(txp, exp, ap.getDistance(p));
+	}
+
+};
+
+#endif // WIFIMODELLOGDIST_H