Table 2.

Main focus of the research works.

Focus	Research Work
Sensor failure detection	[10,14,17,18,26,27,28,29,30,31,32,33,34,35,36]
Maintenance scheduling/management	[14,27,30]
Fault-tolerant ADL recognition	[14,27,30,37,38,39,40,41,42,43,44,45]
Fault-tolerant abnormal behavior detection	[37]
Fault-tolerant indoor localization system/location tracking	[16,46,47]