I. Introduction
Human activity recognition (HAR) is an emerging area of research in the field of pervasive computing. Human activity recognition is broadly classified into two types namely vision based and wearable sensor based. Vision based [1] involves recognition of activities from videos captured by cameras under well controlled laboratory settings. This method does not produce reliable result due to clutter occlusion etc [2]. Privacy issue is another drawback in vision based method. Wearable sensor based method provides robust action recognition in both indoor and outdoor environment.