[Positioner] Add ReferencePoint::friis_idx(AP, pkt)

This function allows to get the Friis index for a single packet in a
measurement instead of for the whole measurement.

owlps-positioner/src/referencepoint.cc

@@ -6,7 +6,6 @@
 
 
 #include "referencepoint.hh"
-#include "measurement.hh"
 #include "calibrationrequest.hh"
 #include "stock.hh"
 
@@ -97,6 +96,7 @@ get_all_measurements(const string &mac_transmitter) const
 
 /**
  * @param mac_transmitter The MAC address of the transmitting mobile.
+ *
  * @return A vector containing all the requests sent by the mobile.
  * The returned vector is empty if no request was sent by the mobile.
  */
@@ -138,6 +138,7 @@ void ReferencePoint::delete_requests()
 /**
  * Note that the requests pointed by the elements of #requests are
  * actually deleted from the Stock.
+ *
  * @returns \em true if at least one request was deleted.
  * @returns \em false if the ReferencePoint was left untouched.
  */
@@ -204,6 +205,7 @@ float ReferencePoint::ss_square_distance(const Request &source) const
 
 /**
  * @param ap_mac The MAC address of the AccessPoint to work on.
+ *
  * @returns The Friis index associated to the AccessPoint.
  * @returns 0 if the AP is unknown at this ReferencePoint.
  */
@@ -224,12 +226,16 @@ friis_index_for_ap(const string &ap_mac) const
 
 
 /**
- * Computes a Friis index for the distance AP-ReferencePoint, based on
- * the measurements of this AP that are present in the ReferencePoint.
+ * Computes a Friis index sum for the distance AP-ReferencePoint,
+ * based on the measurements of this AP that are present in the
+ * ReferencePoint. To obtain the real (averaged) Friis index, one
+ * has to divide the returned sum by the number of indexes.
+ *
  * @param ap The AccessPoint to work on.
  * @param const_term The "constant" part of the computation.
  * @param nb_indexes (result) The number of indexes computed.
- * @return The sum of all Friis indexes for the AccessPoint.
+ *
+ * @returns The sum of all Friis indexes for the AccessPoint.
  * @returns 0 if the AP is unknown at this ReferencePoint.
  */
 float ReferencePoint::friis_indexes_for_ap(
@@ -274,6 +280,54 @@ float ReferencePoint::friis_indexes_for_ap(
 }
 
 
+/**
+ * Computes a Friis index for the distance AP-ReferencePoint, based on a
+ * given packet (\em pkt_id), of a measurement of this AP present in the
+ * ReferencePoint. This measurement is the first found in the
+ * ReferencePoint. This works well when we keep only one calibration
+ * request per reference point.
+ *
+ * @param ap_mac The MAC address of the AccessPoint to work on.
+ * @param pkt_id The packet ID to look for.
+ *
+ * @returns The Friis index for this AP and packet.
+ * @returns 0 if the AP is unknown at this ReferencePoint, or if there
+ * is no packet with the wanted ID.
+ */
+float ReferencePoint::
+friis_index_for_ap(const string &ap_mac, pkt_id_t pkt_id) const
+{
+  const AccessPoint &ap = Stock::get_ap(ap_mac) ;
+  double const_term = ap.friis_constant_term() ;
+  float distance = this->distance(ap.get_coordinates()) ;
+  float friis_idx = 0 ;
+
+  for (vector<CalibrationRequest*>::const_iterator request =
+         requests.begin() ; request != requests.end() ; ++request)
+    {
+      const unordered_map<string, Measurement> &measurements =
+        (*request)->get_measurements() ;
+      unordered_map<string, Measurement>::const_iterator measurement =
+        measurements.find(ap_mac) ;
+      if (measurement == measurements.end())
+        continue ;
+      ss_t ss = measurement->second.get_ss(pkt_id) ;
+      if (ss == 0)
+        continue ;
+
+      assert((*request)->get_mobile()) ;
+      float mobile_gain = (*request)->get_mobile()->get_antenna_gain() ;
+      float mobile_pow = (*request)->get_mobile()->get_trx_power() ;
+      friis_idx =
+        (const_term + mobile_gain + mobile_pow - ss)
+        / (10 * log10(distance)) ;
+      break ;
+    }
+
+  return friis_idx ;
+}
+
+
 
 /* *** Operators *** */
 

owlps-positioner/src/referencepoint.hh

@@ -11,9 +11,9 @@
 class AccessPoint ;
 class CalibrationRequest ;
 class Request ;
-class Measurement ;
 
 #include "point3d.hh"
+#include "measurement.hh"
 
 #include <vector>
 #include <ostream>
@@ -81,6 +81,9 @@ public:
   float friis_indexes_for_ap(
     const AccessPoint &ap, const double &const_term,
     int &nb_indexes) const ;
+  /// Computes the Friis index for the given AccessPoint and packet ID
+  float friis_index_for_ap(
+    const std::string &ap_mac, pkt_id_t pkt_id) const ;
   //@}
 
   /** @name Operators */
@@ -91,7 +94,8 @@ public:
   //@}
 
   /// Displays a ReferencePoint
-  friend std::ostream &operator<<(std::ostream &os, const ReferencePoint &rp) ;
+  friend std::ostream &operator<<(
+    std::ostream &os, const ReferencePoint &rp) ;
 
   /// Hashes a ReferencePoint
   friend std::size_t hash_value(const ReferencePoint &source) ;