133 lines
3.7 KiB
C++
133 lines
3.7 KiB
C++
#ifndef WIFIPROBABILITYGRID_H
|
|
#define WIFIPROBABILITYGRID_H
|
|
|
|
#include <fstream>
|
|
|
|
#include "../../math/distribution/Normal.h"
|
|
#include "../../data/Timestamp.h"
|
|
|
|
#include "WiFiGridNode.h"
|
|
#include "WiFiProbability.h"
|
|
|
|
#include <unordered_set>
|
|
|
|
/**
|
|
* probability is calculated by comparing pre-calculated wifi-signal-strengths
|
|
* attached to each grid-node with a given WiFiMeasurements data structure
|
|
*/
|
|
template <typename Node> class WiFiObserverGrid : public WiFiProbability {
|
|
|
|
|
|
private:
|
|
|
|
/** base-sigma to use for comparison */
|
|
float sigma = 8.0f;
|
|
|
|
/** additional sigma-per-second (measurement age) to*/
|
|
float sigmaPerSecond = 3;
|
|
|
|
std::unordered_set<MACAddress> knownAPs;
|
|
|
|
public:
|
|
|
|
/** ctor with uncertainty */
|
|
WiFiObserverGrid(const float sigma) : sigma(sigma) {
|
|
|
|
//StaticAssert::AinheritsB<Node, WiFiGridNode>();
|
|
|
|
for (const AccessPoint& ap : Node::getMapAPs()) {
|
|
knownAPs.insert(ap.getMAC());
|
|
}
|
|
|
|
Assert::isFalse(knownAPs.empty(), "no APs known to the grid nodes?!");
|
|
|
|
}
|
|
|
|
/**
|
|
* get the given GridNode's probability.
|
|
* compares the predicted signal-strengths stored on the given node
|
|
* with the provided WiFi measurements
|
|
*/
|
|
double getProbability(const Node& n, const Timestamp curTime, const WiFiMeasurements& obs) const {
|
|
|
|
// compile-time sanity check. Node must be a subclass off WiFiGridNode
|
|
//StaticAssert::AinheritsB<Node, WiFiGridNode>();
|
|
|
|
double prob = 1;
|
|
int numMatchingAPs = 0;
|
|
|
|
// after some runtime, check whether the wifi timestamps make sense
|
|
// those must not be zero, otherwise something is wrong!
|
|
if (!obs.entries.empty()) {
|
|
Assert::isFalse(curTime.ms() > 10000 && obs.entries.front().getTimestamp().isZero(), "WiFiMeasurement timestamp is 0. this does not make sense...");
|
|
}
|
|
|
|
// process each observed measurement
|
|
for (const WiFiMeasurement& measurement : obs.entries) {
|
|
|
|
// if an AP is not known to any of the nodes, just skip it
|
|
if (knownAPs.find(measurement.getAP().getMAC()) == knownAPs.end()) {
|
|
continue;}
|
|
|
|
// determine the age for this measurement
|
|
const Timestamp age = curTime - measurement.getTimestamp();
|
|
|
|
// sigma grows with measurement age
|
|
float sigma = this->sigma + this->sigmaPerSecond * age.sec();
|
|
|
|
// the RSSI from the scan
|
|
const float measuredRSSI = measurement.getRSSI();
|
|
|
|
// the RSSI from the model (if available!)
|
|
float modelRSSI = n.getRSSI(measurement.getAP().getMAC());
|
|
|
|
// if no model RSSI is available, that means,
|
|
// the AP in question is not / only barely visible at this location
|
|
// assume a very low signal-strength and increase the sigma
|
|
if (modelRSSI == 0) {
|
|
modelRSSI = -100;
|
|
sigma *= 2;
|
|
}
|
|
|
|
// compare both
|
|
const double p = Distribution::Normal<double>::getProbability(measuredRSSI, sigma, modelRSSI);
|
|
//const double p = Distribution::Region<double>::getProbability(measuredRSSI, sigma, modelRSSI);
|
|
|
|
// adjust using log
|
|
//prob += std::log(p);
|
|
prob *= p;
|
|
|
|
++numMatchingAPs;
|
|
|
|
}
|
|
|
|
// sanity check
|
|
//Assert::isTrue(numMatchingAPs > 0, "not a single measured AP was matched against known ones. coding error? model error?");
|
|
|
|
// as not every node has the same number of visible/matching APs
|
|
// we MUST return something like the average probability
|
|
return prob;
|
|
//return std::pow(prob, 1.0/3.0);
|
|
|
|
}
|
|
|
|
/** gnuplot debug dump */
|
|
void dump(Grid<Node>& grid, const Timestamp curTime, const WiFiMeasurements& obs, const std::string& fileName) {
|
|
|
|
std::ofstream out(fileName);
|
|
out << "splot '-' with points palette\n";
|
|
|
|
for (const Node& n : grid) {
|
|
const float p = getProbability(n, curTime, obs);
|
|
out << n.x_cm << " " << n.y_cm << " " << n.z_cm << " " << p << "\n";
|
|
}
|
|
out << "e\n";
|
|
|
|
out.close();
|
|
|
|
}
|
|
|
|
};
|
|
|
|
#endif // WIFIPROBABILITYGRID_H
|