switch_estimators.h File Reference

#include <switch.h>

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Data Structures
struct	kalman_estimator_s
struct	cusum_kalman_detector_s

Typedefs
typedef struct kalman_estimator_s	kalman_estimator_t
typedef struct cusum_kalman_detector_s	cusum_kalman_detector_t

Functions
void	switch_kalman_init (kalman_estimator_t *est, float Q, float R)
switch_bool_t	switch_kalman_cusum_init (cusum_kalman_detector_t *detect_change, float epsilon, float h)
switch_bool_t	switch_kalman_estimate (kalman_estimator_t *est, float measurement, int system_model)
switch_bool_t	switch_kalman_cusum_detect_change (cusum_kalman_detector_t *detector, float measurement, float rtt_avg)
switch_bool_t	switch_kalman_is_slow_link (kalman_estimator_t *est_loss, kalman_estimator_t *est_rtt)

Typedef Documentation

cusum_kalman_detector_t

typedef struct cusum_kalman_detector_s cusum_kalman_detector_t

Definition at line 80 of file switch_estimators.h.

kalman_estimator_t

typedef struct kalman_estimator_s kalman_estimator_t

Definition at line 79 of file switch_estimators.h.

Function Documentation

switch_kalman_cusum_detect_change()

switch_bool_t switch_kalman_cusum_detect_change	(	cusum_kalman_detector_t *	detector,
		float	measurement,
		float	rtt_avg
	)

Definition at line 142 of file switch_estimators.c.

References cusum_kalman_detector_s::delta, cusum_kalman_detector_s::epsilon, FALSE, cusum_kalman_detector_s::g_last, cusum_kalman_detector_s::h, if(), cusum_kalman_detector_s::last_average, cusum_kalman_detector_s::measurement_noise_e, cusum_kalman_detector_s::N, cusum_kalman_detector_s::P_last, TRUE, cusum_kalman_detector_s::val_desired_last, cusum_kalman_detector_s::variance_Re, and cusum_kalman_detector_s::variance_Rv.

Referenced by process_rtcp_report().

{
        float K=0;
        float P=0;
        float g=0;
        float desired_val;
        float current_average;
        float current_q;
        float sample_variance_Re = 0;

        /*variance*/

        detector->N++;
        current_average = detector->last_average + (measurement - detector->last_average)/detector->N ;
        if (avg > current_average) {
                current_average = avg;
        }
        current_q =  detector-> last_q +  (measurement - detector->last_average) * (measurement - current_average);
        if (detector->N != 0)
        sample_variance_Re = sqrt(current_q/detector->N);

        detector->variance_Re = sample_variance_Re;
        detector->variance_Rv = sample_variance_Re;

        if (sample_variance_Re != 0) {
                K = detector->P_last / (detector->P_last + detector->variance_Re);
                desired_val = detector->val_desired_last + K * (measurement - detector->variance_Re);
                P = (1 - K) * detector->P_last + detector->delta * detector->variance_Rv;
                detector->measurement_noise_e = measurement - desired_val;
                g = detector->g_last + detector->measurement_noise_e - detector->epsilon;
                if (g > detector->h) {
                        detector->delta = 1;
                        g = 0;
                } else {
                        detector->delta = 0;
                }

                /* update last vals for calculating variance */
                detector->last_average = current_average;
                /* update lasts (cusum)*/
                detector -> g_last = g;
                detector -> P_last = P;
                detector -> val_desired_last = desired_val;
        }
        if (detector->delta == 1) {
                return TRUE;
        }
        return FALSE;
}

switch_kalman_cusum_init()

switch_bool_t switch_kalman_cusum_init	(	cusum_kalman_detector_t *	detect_change,
		float	epsilon,
		float	h
	)

Definition at line 113 of file switch_estimators.c.

References FALSE, and TRUE.

Referenced by rtcp_stats_init().

{
        cusum_kalman_detector_t *detector_change = detect_change;


        if (epsilon < 0 || h < 0) {
                return FALSE;
        }

        detector_change -> val_estimate_last = 0;
        detector_change -> val_desired_last = 0;
        detector_change -> P_last = 0;
        detector_change -> K_last = 0;
        detector_change -> delta = 0;
        detector_change -> measurement_noise_e = 0;
        detector_change -> variance_Re = 0;
        detector_change -> measurement_noise_v = 0;
        detector_change -> variance_Rv = 0;
        detector_change -> g_last = 0;
        /*per system model*/
        detector_change -> epsilon = epsilon;
        detector_change -> h = h;
        /*variance*/
        detector_change -> last_average = 0;
        detector_change -> last_q = 0;
        detector_change -> N = 0;
        return TRUE;
}

switch_kalman_estimate()

switch_bool_t switch_kalman_estimate	(	kalman_estimator_t *	est,
		float	measurement,
		int	system_model
	)

Definition at line 195 of file switch_estimators.c.

References EST_JITTER, EST_LOSS, EST_RTT, kalman_estimator_s::K, KALMAN_SYSTEM_MODELS, kalman_estimator_s::P, kalman_estimator_s::P_last, kalman_estimator_s::Q, kalman_estimator_s::R, SWITCH_FALSE, SWITCH_TRUE, kalman_estimator_s::val_estimate_last, and kalman_estimator_s::val_measured.

Referenced by process_rtcp_report().

{
        /*system model can be about: loss, jitter, rtt*/
        float val_estimate;
        float val_temp_est = est->val_estimate_last;
        float P_temp = est->P_last + est->Q;

        if (system_model >= KALMAN_SYSTEM_MODELS) {
                return SWITCH_FALSE ;
        }

        /*sanitize input a little bit, just in case */
        if (system_model == EST_LOSS )  {
                if ((measurement > 100) || (measurement < 0)) {
                        return SWITCH_FALSE ;
                }
        }

        if (system_model == EST_JITTER)  {
                if ((measurement > 10000) || (measurement < 0)) {
                        return SWITCH_FALSE;
                }
        }

        if (system_model == EST_RTT)  {
                if ((measurement > 2 ) || (measurement < 0)) {
                        return SWITCH_FALSE;
                }
        }

        /* calculate the Kalman gain */
        est->K = P_temp * (1.0/(P_temp + est->R));
        /* real life measurement */
        est->val_measured = measurement ;
        val_estimate = val_temp_est + est->K * (est->val_measured - val_temp_est);
        est->P = (1 - est->K) * P_temp;
        /*update lasts*/
        est->P_last = est->P;
        /* save the estimated value (future) */
        est->val_estimate_last = val_estimate;
        return SWITCH_TRUE;
}

switch_kalman_init()

void switch_kalman_init	(	kalman_estimator_t *	est,
		float	Q,
		float	R
	)

Definition at line 70 of file switch_estimators.c.

Referenced by rtcp_stats_init().

{
        est -> val_estimate_last = 0 ;
        est -> P_last = 0;
        est -> Q = Q; /*accuracy of system model */ /* SYSTEM MODEL: TO BE DEDUCTED */
        est -> R = R; /*accuracy of measurement*/ /* SYSTEM MODEL: TO BE DEDUCTED */
        est -> K = 0;
        est -> val_estimate = 0 ;
        est -> val_measured = 0 ; // [0-100 %] or [0-5000] or [0-2sec]
}

switch_kalman_is_slow_link()

switch_bool_t switch_kalman_is_slow_link	(	kalman_estimator_t *	est_loss,
		kalman_estimator_t *	est_rtt
	)

Definition at line 238 of file switch_estimators.c.

References SWITCH_FALSE, SWITCH_TRUE, and kalman_estimator_s::val_estimate_last.

Referenced by process_rtcp_report().

{
        float thresh_packet_loss = 5; /* % */
        float thresh_rtt = 0.8 ; /*seconds*/

        if ((est_loss->val_estimate_last > thresh_packet_loss) &&
                                (est_rtt->val_estimate_last > thresh_rtt )) {
                return SWITCH_TRUE;
        }

        return SWITCH_FALSE;
}