RSS	Received Signal Strength
APs	Access Points
RPs	Reference Points
KPCA	Kernel Principal Component Analysis
APC	Affine Propagation Clustering
ML	Maximum Likelihood
LBSs	Location-Based Services
5G	the Fifth Generation Mobile Communication System
WLAN	Wireless Local Area Network
GPS	Global Position System
IR	Infrared
US	Ultrasound
RFID	Radio Frequency Identification
TOA	Time-Of-Arrival
AOA	Angle-Of-Arrival
KNN	K-Nearest-Neighbor
WKNN	Weighted K-Nearest Neighbor
PCA	Principal Component Analysis
CDF	Cumulative Distribution Function