Table 2.

Comparison of smartphone-only fall detection and prevention systems.

Year	Article	Objective	SP Position	Sensor(s)	Algorithm(s)	Alerting Feature(s)
2009	[34]	Detection	Any	Accelerometer	TBA (Adaptive: depends on user provided parameters)	SMS (time, GPS coordinates, password for activating bidirectional voice call).
	[70]	Detection	Trouser Pocket	Accelerometer	TBA (Fixed)	SMS, voice call, vibration, sound.
2010	[28]	Detection	Chest, Waist, Thigh	Accelerometer & gyroscope	TBA (Fixed)	Sound alarm, voice call.
	[2]	Detection	Trouser Pocket	Accelerometer	Discrete Wavelet Transform (DWT)	SMS (GPS coordinates), email (Google Map), twitter messages.
	[56]	Detection	Chest, Waist, Thigh	Accelerometer	TBA (Fixed)	Audible alarm, voice call.
	[37]	Detection	Waist	Accelerometer	C4.5 DT, NB and SVM	SMS
2011	[9]	Detection	Waist	Accelerometer	TBA (Fixed)	E-mail and/or SMS.
	[44]	Detection	Waist	Accelerometer	TBA (Fixed)	SMS (date, time, location)
	[71]	Detection	Pocket	Accelerometer	TBA (Fixed)	SMS (name, time, GPS coordinates, street address)
	[72]	Detection	Hand, Shirt or Trouser Pocket	Accelerometer & gyroscope	TBA (Fixed), One-Class SVM	Not found
	[45]	Detection	Not found	Accelerometer	TBA (Fixed)	Audible alarm, SMS (GPS coordinates), voice call (manual), remote server draws help path
	[73]	Detection	Shirt Pocket	Accelerometer	TBA (Fixed)	SMS
2012	[26]	Detection	Waist	Accelerometer	TBA (Fixed)	SMS (time, GPS data), draw help path
	[27]	Detection	Waist	Accelerometer	TBA (Fixed), Median filter attenuate noise	MMS (time, map of suspected fall location, and GPS coordinate)
	[31]	Detection	Waist	Accelerometer	TBA (Fixed), ANN 1 based pattern classifier	Notification contains GPS coordinates.
	[54]	uFall for Detection, uTUG for Prevention	Waist	Accelerometer, Gyroscope	TBA (Fixed)	E-mail or SMS, recorded signals are sent to remote server, audio cue (for uTUG)
2012	[74]	Prevention (GUG)	Waist	Accelerometer	Segmentation, filtering, dispersion measures calculation	Not found
	[75]	Detection	Waist (Back)	Accelerometer	SVM, SMLR 2 in SP, NB, DT, KNN 3 in PC	Not found
	[76]	Detection	Shirt or Trouser Pocket	Accelerometer	TBA (Considers axis wise data separately)	Not found
	[77]	Detection	Shirt Pocket	Accelerometer	TBA (Adaptive)	Not found
	[78]	Detection	Shirt Pocket	Accelerometer	TBA (Adaptive)	Text message
	[79]	Detection	Waist	Accelerometer	TBA (Fixed), Median Filter,	MMS (time, GPS coordinate, Google map)
	[80]	Detection	Trouser Pocket	Accelerometer	SVM classifier	Vibration, sound alarm, SMS (time, location, & health information)
	[64]	Detection	Waist	Accelerometer, Wi-Fi module	DT Classifier, location estimation using RSSI 4	SMS (name, time, location)
	[81]	Detection	Hand, Pocket, waist	Accelerometer, Gyroscope	Semi-supervised learning	Not found
	[82]	Detection	Not found	Accelerometer, Gyroscope	Not found	SMS (location),
	[83]	Detection	Chest, Waist, Thigh	Accelerometer	TBA (Adjusted based on user's profile)	SMS
	[84]	Detection	Hand, Pocket	Accelerometer, Gyroscope	TBA (Fixed)	Not found
2013	[57]	Detection	Trouser Pocket	Accelerometer	TBA (Fixed)	SMS (date, time, GPS data), voice call, vibration, sound.
	[8]	Detection	Chest	Accelerometer, Gyroscope, & Magnetometer	Fisher's discriminant ratio and J3 criterion	MMS (time, map of suspected fall location, GPS coordinate)
	[22]	Prevention	Trouser Pocket	Accelerometer & Gyroscope	C4.5 DT classifier, Hjorth mobility and complexity [42]	Alert the user about imminent fall by using message & vibration.
	[33]	Detection	Waist	Accelerometer	TBA (Fixed)	SMS, voice call, others: twitter, email, Facebook.
	[55]	Detection	Not found	Accelerometer	TBA (Fixed)	SP trigger PC via Wi-Fi, PC send alert via SMS, emails or/and voice calls
	[58]	Detection	Waist	Accelerometer	TBA (Fixed)	SMS (time, GPS data), draw help path
	[85]	Detection	Not found	Accelerometer	TBA (Fixed)	Not found
	[86]	Detection	(User's height 164 cm)	Accelerometer	TBA (Fixed)	Server displays current states and triggers an alarm
	[87]	Detection	Trouser Pocket	Accelerometer	OneRAttributeEval, ReliefFAttributeEval SVMAttributeEval, K* [88], C4.5, NB	SMS (GPS coordinate)
	[89]	Detection (Free Fall)	Not found	Accelerometer	Displacement based algorithms	SMS (GPS coordinate)
	[90]	Detection	Waist	Accelerometer	TBA (Fixed)	SMS

^1.Artificial Neural Network;

^2.Sparse Multinomial Logistic Regression (SMLR);

^3.k-Nearest Neighbours (KNN);

^4.Received Signal Strength Indication.