1 /*
2 * Copyright (C) 2018 Alberto Irurueta Carro (alberto@irurueta.com)
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package com.irurueta.navigation.indoor.radiosource;
17
18 import com.irurueta.geometry.Point;
19 import com.irurueta.navigation.LockedException;
20 import com.irurueta.navigation.indoor.RadioSource;
21 import com.irurueta.navigation.indoor.RangingAndRssiReadingLocated;
22 import com.irurueta.navigation.indoor.Utils;
23 import com.irurueta.numerical.robust.RobustEstimatorMethod;
24
25 import java.util.List;
26
27 /**
28 * This is an abstract class to robustly estimate position, transmitted power and path-loss
29 * exponent of a radio source (e.g. Wi-Fi access point or bluetooth beacon), by discarding
30 * outliers and assuming that the ranging data is available to obtain position with
31 * greater accuracy and that the radio source emits isotropically following the
32 * expression below:
33 * Pr = Pt*Gt*Gr*lambda^2 / (4*pi*d)^2,
34 * where Pr is the received power (expressed in mW),
35 * Gt is the Gain of the transmission antenna
36 * Gr is the Gain of the receiver antenna
37 * d is the distance between emitter and receiver
38 * and lambda is the wavelength and is equal to: lambda = c / f,
39 * where c is the speed of light
40 * and f is the carrier frequency of the radio signal.
41 * Because usually information about the antenna of the radio source cannot be
42 * retrieved (because many measurements are made on unknown devices where
43 * physical access is not possible), this implementation will estimate the
44 * equivalent transmitted power as: Pte = Pt * Gt * Gr.
45 * If Readings contain RSSI standard deviations, those values will be used,
46 * otherwise it will be assumed an RSSI standard deviation of 1 dB.
47 * <p>
48 * Although RobustRssiRadioSourceEstimator can estimate the same parameters of a radio
49 * source, when ranging measures are available along with RSSI measurements,
50 * implementations of this class should be preferred instead as they can provide
51 * greater accuracy.
52 *
53 * @param <S> a {@link RadioSource} type.
54 * @param <P> a {@link Point} type.
55 */
56 @SuppressWarnings("Duplicates")
57 public abstract class RobustRangingAndRssiRadioSourceEstimator<S extends RadioSource, P extends Point<P>>
58 extends RobustRadioSourceEstimator<P, RangingAndRssiReadingLocated<S, P>,
59 RobustRangingAndRssiRadioSourceEstimatorListener<S, P>> {
60
61 /**
62 * Indicates that by default position covariances of readings must be taken into account to increase
63 * the amount of standard deviation of each ranging measure by the amount of position standard deviation
64 * assuming that both measures are statistically independent.
65 */
66 public static final boolean DEFAULT_USE_READING_POSITION_COVARIANCES = true;
67
68 /**
69 * Initially transmitted power to start the estimation of radio source
70 * transmitted power.
71 * If not defined, average value of received power readings will be used.
72 */
73 protected Double initialTransmittedPowerdBm;
74
75 /**
76 * Initial position to start the estimation of radio source position.
77 * If not defined, centroid of provided located readings will be used.
78 */
79 protected P initialPosition;
80
81 /**
82 * Initial exponent typically used on free space for path loss propagation in
83 * terms of distance.
84 * On different environments path loss exponent might have different values:
85 * - Free space: 2.0
86 * - Urban Area: 2.7 to 3.5
87 * - Suburban Area: 3 to 5
88 * - Indoor (line-of-sight): 1.6 to 1.8
89 * <p>
90 * If path loss exponent estimation is enabled, estimation will start at this
91 * value and will converge to the most appropriate value.
92 * If path loss exponent estimation is disabled, this value will be assumed
93 * to be exact and the estimated path loss exponent will be equal to this
94 * value.
95 */
96 protected double initialPathLossExponent = RangingAndRssiRadioSourceEstimator.DEFAULT_PATH_LOSS_EXPONENT;
97
98 /**
99 * Indicates whether transmitted power estimation is enabled or not.
100 */
101 protected boolean transmittedPowerEstimationEnabled =
102 RangingAndRssiRadioSourceEstimator.DEFAULT_TRANSMITTED_POWER_ESTIMATION_ENABLED;
103
104 /**
105 * Indicates whether path loss estimation is enabled or not.
106 */
107 protected boolean pathLossEstimationEnabled;
108
109 /**
110 * Estimated transmitted power expressed in dBm's.
111 */
112 protected double estimatedTransmittedPowerdBm;
113
114 /**
115 * Estimated exponent typically used on free space for path loss propagation in
116 * terms of distance.
117 * On different environments path loss exponent might have different values:
118 * - Free space: 2.0
119 * - Urban Area: 2.7 to 3.5
120 * - Suburban Area: 3 to 5
121 * - Indoor (line-of-sight): 1.6 to 1.8
122 * If path loss exponent estimation is not enabled, this value will always be equal to
123 * {@link RssiRadioSourceEstimator#DEFAULT_PATH_LOSS_EXPONENT}
124 */
125 protected double estimatedPathLossExponent = RangingAndRssiRadioSourceEstimator.DEFAULT_PATH_LOSS_EXPONENT;
126
127 /**
128 * Variance of estimated transmitted power.
129 * This value will only be available when transmitted power
130 * estimation is enabled.
131 */
132 protected Double estimatedTransmittedPowerVariance;
133
134 /**
135 * Variance of estimated path loss exponent.
136 * This value will only be available when path-loss
137 * exponent estimation is enabled.
138 */
139 protected Double estimatedPathLossExponentVariance;
140
141 /**
142 * Indicates whether position covariances of readings must be taken into account to increase
143 * the amount of standard deviation of each ranging measure by the amount of position standard deviation
144 * assuming that both measures are statistically independent.
145 */
146 protected boolean useReadingPositionCovariances = DEFAULT_USE_READING_POSITION_COVARIANCES;
147
148 /**
149 * Constructor.
150 */
151 protected RobustRangingAndRssiRadioSourceEstimator() {
152 super();
153 }
154
155 /**
156 * Constructor.
157 * Sets signal readings belonging to the same radio source.
158 *
159 * @param readings signal readings belonging to the same radio source.
160 * @throws IllegalArgumentException if readings are not valid.
161 */
162 protected RobustRangingAndRssiRadioSourceEstimator(
163 final List<? extends RangingAndRssiReadingLocated<S, P>> readings) {
164 super(readings);
165 }
166
167 /**
168 * Constructor.
169 *
170 * @param listener listener in charge of attending events raised by this instance.
171 */
172 protected RobustRangingAndRssiRadioSourceEstimator(
173 final RobustRangingAndRssiRadioSourceEstimatorListener<S, P> listener) {
174 super(listener);
175 }
176
177 /**
178 * Constructor.
179 * Sets signal readings belonging to the same radio source.
180 *
181 * @param readings signal readings belonging to the same radio source.
182 * @param listener listener in charge of attending events raised by this instance.
183 * @throws IllegalArgumentException if readings are not valid.
184 */
185 protected RobustRangingAndRssiRadioSourceEstimator(
186 final List<? extends RangingAndRssiReadingLocated<S, P>> readings,
187 final RobustRangingAndRssiRadioSourceEstimatorListener<S, P> listener) {
188 super(readings, listener);
189 }
190
191 /**
192 * Constructor.
193 * Sets signal readings belonging to the same radio source.
194 *
195 * @param readings signal readings belonging to the same radio source.
196 * @param initialPosition initial position to start the estimation of radio
197 * source position.
198 * @throws IllegalArgumentException if readings are not valid.
199 */
200 protected RobustRangingAndRssiRadioSourceEstimator(
201 final List<? extends RangingAndRssiReadingLocated<S, P>> readings, final P initialPosition) {
202 super(readings);
203 this.initialPosition = initialPosition;
204 }
205
206 /**
207 * Constructor.
208 *
209 * @param initialPosition initial position to start the estimation of radio
210 * source position.
211 */
212 protected RobustRangingAndRssiRadioSourceEstimator(final P initialPosition) {
213 this.initialPosition = initialPosition;
214 }
215
216 /**
217 * Constructor.
218 *
219 * @param initialPosition initial position to start the estimation of radio
220 * source position.
221 * @param listener listener in charge of attending events raised by this instance.
222 */
223 protected RobustRangingAndRssiRadioSourceEstimator(
224 final P initialPosition, final RobustRangingAndRssiRadioSourceEstimatorListener<S, P> listener) {
225 super(listener);
226 this.initialPosition = initialPosition;
227 }
228
229 /**
230 * Constructor.
231 * Sets signal readings belonging to the same radio source.
232 *
233 * @param readings signal readings belonging to the same radio source.
234 * @param initialPosition initial position to start the estimation of radio
235 * source position.
236 * @param listener listener in charge of attending events raised by this instance.
237 * @throws IllegalArgumentException if readings are not valid.
238 */
239 protected RobustRangingAndRssiRadioSourceEstimator(
240 final List<? extends RangingAndRssiReadingLocated<S, P>> readings, final P initialPosition,
241 final RobustRangingAndRssiRadioSourceEstimatorListener<S, P> listener) {
242 super(readings, listener);
243 this.initialPosition = initialPosition;
244 }
245
246 /**
247 * Constructor.
248 *
249 * @param initialTransmittedPowerdBm initial transmitted power to start the
250 * estimation of radio source transmitted power
251 * (expressed in dBm's)
252 */
253 protected RobustRangingAndRssiRadioSourceEstimator(final Double initialTransmittedPowerdBm) {
254 this.initialTransmittedPowerdBm = initialTransmittedPowerdBm;
255 }
256
257 /**
258 * Constructor.
259 * Sets signal readings belonging to the same radio source.
260 *
261 * @param readings signal readings belonging to the same radio source.
262 * @param initialTransmittedPowerdBm initial transmitted power to start the
263 * estimation of radio source transmitted power
264 * (expressed in dBm's)
265 * @throws IllegalArgumentException if readings are not valid.
266 */
267 protected RobustRangingAndRssiRadioSourceEstimator(
268 final List<? extends RangingAndRssiReadingLocated<S, P>> readings,
269 final Double initialTransmittedPowerdBm) {
270 super(readings);
271 this.initialTransmittedPowerdBm = initialTransmittedPowerdBm;
272 }
273
274 /**
275 * Constructor.
276 *
277 * @param initialTransmittedPowerdBm initial transmitted power to start the
278 * estimation of radio source transmitted power
279 * (expressed in dBm's)
280 * @param listener listener in charge of attending events raised by this instance.
281 */
282 protected RobustRangingAndRssiRadioSourceEstimator(
283 final Double initialTransmittedPowerdBm,
284 final RobustRangingAndRssiRadioSourceEstimatorListener<S, P> listener) {
285 super(listener);
286 this.initialTransmittedPowerdBm = initialTransmittedPowerdBm;
287 }
288
289 /**
290 * Constructor.
291 * Sets signal readings belonging to the same radio source.
292 *
293 * @param readings signal readings belonging to the same radio source.
294 * @param initialTransmittedPowerdBm initial transmitted power to start the
295 * estimation of radio source transmitted power
296 * (expressed in dBm's)
297 * @param listener listener in charge of attending events raised by this instance.
298 * @throws IllegalArgumentException if readings are not valid.
299 */
300 protected RobustRangingAndRssiRadioSourceEstimator(
301 final List<? extends RangingAndRssiReadingLocated<S, P>> readings, final Double initialTransmittedPowerdBm,
302 final RobustRangingAndRssiRadioSourceEstimatorListener<S, P> listener) {
303 super(readings, listener);
304 this.initialTransmittedPowerdBm = initialTransmittedPowerdBm;
305 }
306
307 /**
308 * Constructor.
309 * Sets signal readings belonging to the same radio source.
310 *
311 * @param readings signal readings belonging to the same radio source.
312 * @param initialPosition initial position to start the estimation of radio
313 * source position.
314 * @param initialTransmittedPowerdBm initial transmitted power to start the
315 * estimation of radio source transmitted power
316 * (expressed in dBm's).
317 * @throws IllegalArgumentException if readings are not valid.
318 */
319 protected RobustRangingAndRssiRadioSourceEstimator(
320 final List<? extends RangingAndRssiReadingLocated<S, P>> readings, final P initialPosition,
321 final Double initialTransmittedPowerdBm) {
322 super(readings);
323 this.initialPosition = initialPosition;
324 this.initialTransmittedPowerdBm = initialTransmittedPowerdBm;
325 }
326
327 /**
328 * Constructor.
329 *
330 * @param initialPosition initial position to start the estimation of radio
331 * source position.
332 * @param initialTransmittedPowerdBm initial transmitted power to start the
333 * estimation of radio source transmitted power
334 * (expressed in dBm's).
335 */
336 protected RobustRangingAndRssiRadioSourceEstimator(
337 final P initialPosition, final Double initialTransmittedPowerdBm) {
338 this.initialPosition = initialPosition;
339 this.initialTransmittedPowerdBm = initialTransmittedPowerdBm;
340 }
341
342 /**
343 * Constructor.
344 *
345 * @param initialPosition initial position to start the estimation of radio
346 * source position.
347 * @param initialTransmittedPowerdBm initial transmitted power to start the
348 * estimation of radio source transmitted power
349 * (expressed in dBm's).
350 * @param listener in charge of attending events raised by this instance.
351 */
352 protected RobustRangingAndRssiRadioSourceEstimator(
353 final P initialPosition, final Double initialTransmittedPowerdBm,
354 final RobustRangingAndRssiRadioSourceEstimatorListener<S, P> listener) {
355 super(listener);
356 this.initialPosition = initialPosition;
357 this.initialTransmittedPowerdBm = initialTransmittedPowerdBm;
358 }
359
360 /**
361 * Constructor.
362 * Sets signal readings belonging to the same radio source.
363 *
364 * @param readings signal readings belonging to the same radio source.
365 * @param initialPosition initial position to start the estimation of radio
366 * source position.
367 * @param initialTransmittedPowerdBm initial transmitted power to start the
368 * estimation of radio source transmitted power
369 * (expressed in dBm's).
370 * @param listener listener in charge of attending events raised by this instance.
371 * @throws IllegalArgumentException if readings are not valid.
372 */
373 protected RobustRangingAndRssiRadioSourceEstimator(
374 final List<? extends RangingAndRssiReadingLocated<S, P>> readings, final P initialPosition,
375 final Double initialTransmittedPowerdBm,
376 final RobustRangingAndRssiRadioSourceEstimatorListener<S, P> listener) {
377 super(readings, listener);
378 this.initialPosition = initialPosition;
379 this.initialTransmittedPowerdBm = initialTransmittedPowerdBm;
380 }
381
382 /**
383 * Constructor.
384 * Sets signal readings belonging to the same radio source.
385 *
386 * @param readings signal readings belonging to the same radio source.
387 * @param initialPosition initial position to start the estimation of radio
388 * source position.
389 * @param initialTransmittedPowerdBm initial transmitted power to start the
390 * estimation of radio source transmitted power
391 * (expressed in dBm's).
392 * @param initialPathLossExponent initial path loss exponent. A typical value is 2.0.
393 * @throws IllegalArgumentException if readings are not valid.
394 */
395 protected RobustRangingAndRssiRadioSourceEstimator(
396 final List<? extends RangingAndRssiReadingLocated<S, P>> readings, final P initialPosition,
397 final Double initialTransmittedPowerdBm, final double initialPathLossExponent) {
398 this(readings, initialPosition, initialTransmittedPowerdBm);
399 this.initialPathLossExponent = initialPathLossExponent;
400 }
401
402 /**
403 * Constructor.
404 *
405 * @param initialPosition initial position to start the estimation of radio
406 * source position.
407 * @param initialTransmittedPowerdBm initial transmitted power to start the
408 * estimation of radio source transmitted power
409 * (expressed in dBm's).
410 * @param initialPathLossExponent initial path loss exponent. A typical value is 2.0.
411 */
412 protected RobustRangingAndRssiRadioSourceEstimator(
413 final P initialPosition, final Double initialTransmittedPowerdBm, final double initialPathLossExponent) {
414 this(initialPosition, initialTransmittedPowerdBm);
415 this.initialPathLossExponent = initialPathLossExponent;
416 }
417
418 /**
419 * Constructor.
420 *
421 * @param initialPosition initial position to start the estimation of radio
422 * source position.
423 * @param initialTransmittedPowerdBm initial transmitted power to start the
424 * estimation of radio source transmitted power
425 * (expressed in dBm's).
426 * @param initialPathLossExponent initial path loss exponent. A typical value is 2.0.
427 * @param listener listener in charge of attending events raised by this instance.
428 */
429 protected RobustRangingAndRssiRadioSourceEstimator(
430 final P initialPosition, final Double initialTransmittedPowerdBm, final double initialPathLossExponent,
431 final RobustRangingAndRssiRadioSourceEstimatorListener<S, P> listener) {
432 this(initialPosition, initialTransmittedPowerdBm, listener);
433 this.initialPathLossExponent = initialPathLossExponent;
434 }
435
436 /**
437 * Constructor.
438 * Sets signal readings belonging to the same radio source.
439 *
440 * @param readings signal readings belonging to the same radio source.
441 * @param initialPosition initial position to start the estimation of radio
442 * source position.
443 * @param initialTransmittedPowerdBm initial transmitted power to start the
444 * estimation of radio source transmitted power
445 * (expressed in dBm's).
446 * @param initialPathLossExponent initial path loss exponent. A typical value is 2.0.
447 * @param listener listener in charge of attending events raised by this instance.
448 * @throws IllegalArgumentException if readings are not valid.
449 */
450 protected RobustRangingAndRssiRadioSourceEstimator(
451 final List<? extends RangingAndRssiReadingLocated<S, P>> readings, final P initialPosition,
452 final Double initialTransmittedPowerdBm, final double initialPathLossExponent,
453 final RobustRangingAndRssiRadioSourceEstimatorListener<S, P> listener) {
454 this(readings, initialPosition, initialTransmittedPowerdBm, listener);
455 this.initialPathLossExponent = initialPathLossExponent;
456 }
457
458 /**
459 * Gets initial transmitted power to start the estimation of radio source
460 * transmitted power (expressed in dBm's).
461 * If not defined, average value of received power readings will be used.
462 *
463 * @return initial transmitted power to start the estimation of radio source
464 * transmitted power.
465 */
466 public Double getInitialTransmittedPowerdBm() {
467 return initialTransmittedPowerdBm;
468 }
469
470 /**
471 * Sets initial transmitted power to start the estimation of radio source
472 * transmitted power (expressed in dBm's).
473 * If not defined, average value of received power readings will be used.
474 *
475 * @param initialTransmittedPowerdBm initial transmitted power to start the
476 * estimation of radio source transmitted
477 * power.
478 * @throws LockedException if estimator is locked.
479 */
480 public void setInitialTransmittedPowerdBm(final Double initialTransmittedPowerdBm) throws LockedException {
481 if (isLocked()) {
482 throw new LockedException();
483 }
484 this.initialTransmittedPowerdBm = initialTransmittedPowerdBm;
485 }
486
487 /**
488 * Gets initial transmitted power to start the estimation of radio source
489 * transmitted power (expressed in mW).
490 * If not defined, average value of received power readings will be used.
491 *
492 * @return initial transmitted power to start the estimation of radio source
493 * transmitted power.
494 */
495 public Double getInitialTransmittedPower() {
496 return initialTransmittedPowerdBm != null ? Utils.dBmToPower(initialTransmittedPowerdBm) : null;
497 }
498
499 /**
500 * Sets initial transmitted power to start the estimation of radio source
501 * transmitted power (expressed in mW).
502 * If not defined, average value of received power readings will be used.
503 *
504 * @param initialTransmittedPower initial transmitted power to start the
505 * estimation of radio source transmitted power.
506 * @throws LockedException if estimator is locked.
507 * @throws IllegalArgumentException if provided value is negative.
508 */
509 public void setInitialTransmittedPower(final Double initialTransmittedPower) throws LockedException {
510 if (isLocked()) {
511 throw new LockedException();
512 }
513 if (initialTransmittedPower != null) {
514 if (initialTransmittedPower < 0.0) {
515 throw new IllegalArgumentException();
516 }
517 initialTransmittedPowerdBm = Utils.powerTodBm(initialTransmittedPower);
518 } else {
519 initialTransmittedPowerdBm = null;
520 }
521 }
522
523 /**
524 * Gets initial position to start the estimation of radio source position.
525 * If not defined, centroid of provided fingerprints will be used.
526 *
527 * @return initial position to start the estimation of radio source position.
528 */
529 public P getInitialPosition() {
530 return initialPosition;
531 }
532
533 /**
534 * Sets initial position to start the estimation of radio source position.
535 * If not defined, centroid of provided fingerprints will be used.
536 *
537 * @param initialPosition initial position to start the estimation of radio
538 * source position.
539 * @throws LockedException if estimator is locked.
540 */
541 public void setInitialPosition(final P initialPosition) throws LockedException {
542 if (isLocked()) {
543 throw new LockedException();
544 }
545 this.initialPosition = initialPosition;
546 }
547
548 /**
549 * Gets initial exponent typically used on free space for path loss propagation
550 * in terms of distance.
551 * On different environments path loss exponent might have different value:
552 * - Free space: 2.0
553 * - Urban Area: 2.7 to 3.5
554 * - Suburban Area: 3 to 5
555 * - Indoor (line-of-sight): 1.6 to 1.8
556 * <p>
557 * If path loss exponent estimation is enabled, estimation will start at this
558 * value and will converge to the most appropriate value.
559 * If path loss exponent estimation is disabled, this value will be assumed
560 * to be exact and the estimated path loss exponent will be equal to this
561 * value.
562 *
563 * @return initial path loss exponent.
564 */
565 public double getInitialPathLossExponent() {
566 return initialPathLossExponent;
567 }
568
569 /**
570 * Sets initial exponent typically used on free space for path loss propagation
571 * in terms of distance.
572 * On different environments path loss exponent might have different value:
573 * - Free space: 2.0
574 * - Urban Area: 2.7 to 3.5
575 * - Suburban Area: 3 to 5
576 * - Indoor (line-of-sight): 1.6 to 1.8
577 * <p>
578 * If path loss exponent estimation is enabled, estimation will start at this
579 * value and will converge to the most appropriate value.
580 * If path loss exponent estimation is disabled, this value will be assumed
581 * to be exact and the estimated path loss exponent will be equal to this
582 * value.
583 *
584 * @param initialPathLossExponent initial path loss exponent.
585 * @throws LockedException if estimator is locked.
586 */
587 public void setInitialPathLossExponent(final double initialPathLossExponent) throws LockedException {
588 if (isLocked()) {
589 throw new LockedException();
590 }
591 this.initialPathLossExponent = initialPathLossExponent;
592 }
593
594 /**
595 * Indicates whether transmitted power estimation is enabled or not.
596 *
597 * @return true if transmitted power estimation is enabled, false otherwise.
598 */
599 public boolean isTransmittedPowerEstimationEnabled() {
600 return transmittedPowerEstimationEnabled;
601 }
602
603 /**
604 * Specifies whether transmitted power estimation is enabled or not.
605 *
606 * @param transmittedPowerEstimationEnabled true if transmitted power estimation is enabled,
607 * false otherwise.
608 * @throws LockedException if estimator is locked.
609 */
610 public void setTransmittedPowerEstimationEnabled(final boolean transmittedPowerEstimationEnabled)
611 throws LockedException {
612 if (isLocked()) {
613 throw new LockedException();
614 }
615 this.transmittedPowerEstimationEnabled = transmittedPowerEstimationEnabled;
616 }
617
618 /**
619 * Indicates whether path loss estimation is enabled or not.
620 *
621 * @return true if path loss estimation is enabled, false otherwise.
622 */
623 public boolean isPathLossEstimationEnabled() {
624 return pathLossEstimationEnabled;
625 }
626
627 /**
628 * Specifies whether path loss estimation is enabled or not.
629 *
630 * @param pathLossEstimationEnabled true if path loss estimation is enabled,
631 * false otherwise.
632 * @throws LockedException if estimator is locked.
633 */
634 public void setPathLossEstimationEnabled(final boolean pathLossEstimationEnabled) throws LockedException {
635 if (isLocked()) {
636 throw new LockedException();
637 }
638 this.pathLossEstimationEnabled = pathLossEstimationEnabled;
639 }
640
641 /**
642 * Indicates whether position covariances of readings must be taken into account to increase
643 * the amount of standard deviation of each ranging measure by the amount of position standard
644 * deviation assuming that both measures are statistically independent.
645 *
646 * @return true to take into account reading position covariances, false otherwise.
647 */
648 public boolean getUseReadingPositionCovariance() {
649 return useReadingPositionCovariances;
650 }
651
652 /**
653 * Specifies whether position covariances of readings must be taken into account to increase
654 * the amount of standard deviation of each ranging measure by the amount of position standard
655 * deviation assuming that both measures are statistically independent.
656 *
657 * @param useReadingPositionCovariances true to take into account reading position covariances, false
658 * otherwise.
659 * @throws LockedException if estimator is locked.
660 */
661 public void setUseReadingPositionCovariances(final boolean useReadingPositionCovariances) throws LockedException {
662 if (isLocked()) {
663 throw new LockedException();
664 }
665 this.useReadingPositionCovariances = useReadingPositionCovariances;
666 }
667
668 /**
669 * Indicates whether an homogeneous linear solver is used to estimate an initial
670 * position for the internal ranging radio source estimator.
671 *
672 * @return true if homogeneous linear solver is used, false if an inhomogeneous linear
673 * one is used instead.
674 */
675 public abstract boolean isHomogeneousRangingLinearSolverUsed();
676
677 /**
678 * Specifies whether an homogeneous linear solver is used to estimate an initial
679 * position for the internal ranging radio source estimator.
680 *
681 * @param useHomogeneousLinearSolver true if homogeneous linear solver is used, false
682 * if an inhomogeneous linear one is used instead.
683 * @throws LockedException if estimator is locked.
684 */
685 public abstract void setHomogeneousRangingLinearSolverUsed(final boolean useHomogeneousLinearSolver)
686 throws LockedException;
687
688 /**
689 * Indicates whether this instance is ready to start the estimation.
690 *
691 * @return true if this instance is ready, false otherwise.
692 */
693 @Override
694 public boolean isReady() {
695 // if transmitted power estimation is disabled, an initial transmitted power must be provided
696 return !(!transmittedPowerEstimationEnabled && initialTransmittedPowerdBm == null)
697 // readings must also be valid
698 && areValidReadings(readings);
699 }
700
701 /**
702 * Gets estimated transmitted power variance.
703 * This is only available when result has been refined and covariance is kept.
704 *
705 * @return estimated transmitted power variance.
706 */
707 public Double getEstimatedTransmittedPowerVariance() {
708 return estimatedTransmittedPowerVariance;
709 }
710
711 /**
712 * Gets estimated path loss exponent variance.
713 * This is only available when result has been refined and covariance is kept.
714 *
715 * @return estimated path loss exponent variance.
716 */
717 public Double getEstimatedPathLossExponentVariance() {
718 return estimatedPathLossExponentVariance;
719 }
720
721 /**
722 * Gets estimated transmitted power expressed in milli watts (mW).
723 *
724 * @return estimated transmitted power expressed in milli watts.
725 */
726 public double getEstimatedTransmittedPower() {
727 return Utils.dBmToPower(estimatedTransmittedPowerdBm);
728 }
729
730 /**
731 * Gets estimated transmitted power expressed in dBm's.
732 *
733 * @return estimated transmitted power expressed in dBm's.
734 */
735 public double getEstimatedTransmittedPowerdBm() {
736 return estimatedTransmittedPowerdBm;
737 }
738
739 /**
740 * Gets estimated exponent typically used on free space for path loss propagation in
741 * terms of distance.
742 * On different environments path loss exponent might have different values:
743 * - Free space: 2.0
744 * - Urban Area: 2.7 to 3.5
745 * - Suburban Area: 3 to 5
746 * - Indoor (line-of-sight): 1.6 to 1.8
747 * If path loss exponent estimation is not enabled, this value will always be equal to
748 * {@link RssiRadioSourceEstimator#DEFAULT_PATH_LOSS_EXPONENT}
749 *
750 * @return estimated path loss exponent.
751 */
752 public double getEstimatedPathLossExponent() {
753 return estimatedPathLossExponent;
754 }
755
756 /**
757 * Returns method being used for robust estimation.
758 *
759 * @return method being used for robust estimation.
760 */
761 public abstract RobustEstimatorMethod getMethod();
762
763 /**
764 * Solves preliminary solution for a subset of samples.
765 *
766 * @param samplesIndices indices of subset samples.
767 * @param solutions instance where solution will be stored.
768 */
769 protected abstract void solvePreliminarySolutions(final int[] samplesIndices, final List<Solution<P>> solutions);
770
771 /**
772 * Estimates residual for a solution obtained for a subset of samples.
773 *
774 * @param currentEstimation solution obtained for a subset of samples.
775 * @param i i-th fingerprint to obtain residual for.
776 * @return difference between measured and expected RSSI value.
777 */
778 protected double residual(final Solution<P> currentEstimation, final int i) {
779 // Model fitted internally is equal to:
780 // Pr (dBm) = 10 * log(Pte * k^n / d^n) = 10*n*log(k) + 10*log(Pte) - 5*n*log(d^2)
781 // where:
782 // Pr is received, expressed in dBm
783 // Pte is equivalent transmitted power, expressed in dBm
784 // k is a constant equal to k = c^2 / (pi * f)^2, where c is speed of light
785 // and d is equal to distance between fingerprint and estimated position
786 final var reading = readings.get(i);
787 final var frequency = reading.getSource().getFrequency();
788
789 final var pathLossExponent = currentEstimation.getEstimatedPathLossExponent();
790
791 // compute k as the constant part of the isotropic received power formula
792 // so that: Pr = Pte*k^n/d^n
793 final var k = RssiRadioSourceEstimator.SPEED_OF_LIGHT / (4.0 * Math.PI * frequency);
794 final var kdB = 10.0 * pathLossExponent * Math.log10(k);
795
796 // get distance from estimated radio source position and reading position
797 final var readingPosition = reading.getPosition();
798 final var radioSourcePosition = currentEstimation.getEstimatedPosition();
799
800 final var sqrDistance = radioSourcePosition.sqrDistanceTo(readingPosition);
801
802 final var transmittedPowerdBm = currentEstimation.getEstimatedTransmittedPowerdBm();
803
804 // compute expected received power assuming isotropic transmission
805 // and compare against measured RSSI at fingerprint location
806 final var expectedRSSI = kdB + transmittedPowerdBm - 5.0 * pathLossExponent * Math.log10(sqrDistance);
807 final var rssi = reading.getRssi();
808
809 return Math.abs(expectedRSSI - rssi);
810 }
811
812 /**
813 * Contains a solution obtained during robust estimation for a subset of
814 * samples.
815 *
816 * @param <P> a {@link Point} type.
817 */
818 protected static class Solution<P extends Point<?>> {
819 /**
820 * Estimated position for a subset of samples.
821 */
822 private final P estimatedPosition;
823
824 /**
825 * Estimated transmitted power expressed in dBm's for a subset of samples.
826 */
827 private final double estimatedTransmittedPowerdBm;
828
829 /**
830 * Estimated path loss exponent for a subset of samples.
831 */
832 private final double estimatedPathLossExponent;
833
834 /**
835 * Constructor.
836 *
837 * @param estimatedPosition estimated position for a subset of samples.
838 * @param estimatedTransmittedPowerdBm estimated transmitted power expressed
839 * in dBm's for a subset of samples.
840 * @param estimatedPathLossExponent estimated path loss exponent.
841 */
842 public Solution(final P estimatedPosition, final double estimatedTransmittedPowerdBm,
843 final double estimatedPathLossExponent) {
844 this.estimatedPosition = estimatedPosition;
845 this.estimatedTransmittedPowerdBm = estimatedTransmittedPowerdBm;
846 this.estimatedPathLossExponent = estimatedPathLossExponent;
847 }
848
849 /**
850 * Gets estimated position for a subset of samples.
851 *
852 * @return estimated position for a subset of samples.
853 */
854 public P getEstimatedPosition() {
855 return estimatedPosition;
856 }
857
858 /**
859 * Gets estimated transmitted power expressed in dBm's for a subset of
860 * samples.
861 *
862 * @return estimated transmitted power expressed in dBm's for a subset
863 * of samples.
864 */
865 public double getEstimatedTransmittedPowerdBm() {
866 return estimatedTransmittedPowerdBm;
867 }
868
869 /**
870 * Gets estimated path loss exponent.
871 *
872 * @return estimated path loss exponent.
873 */
874 public double getEstimatedPathLossExponent() {
875 return estimatedPathLossExponent;
876 }
877 }
878 }