A processor implemented method, comprising: obtaining, using a radar system, a plurality of time domain signals reflected by a subject performing one or more activities; identifying, one or more gesture windows in the plurality of obtained time domain signals, by applying one or more signal properties on the plurality of obtained time domain signals to detect a no motion region and a motion region in the plurality of obtained time domain signals, wherein width of each gesture window is indicative of a time duration in which a gesture is performed, and wherein the one or more gesture windows are identified by eliminating a portion of the plurality of obtained time domain signals with no motion; obtaining, using a spectrogram, one or more shapelets of one or more gestures captured from the one or more gesture windows; creating a dictionary of basic shapelets of one or more motion patterns of a plurality of gestures comprised in the one or more activities performed by the subject; decomposing, using the created dictionary of basic shapelets, the one or more shapelets to obtain a plurality of sub-shapelets of the one or more gestures captured from the one or more gesture windows, wherein each sub-shapelet is representative of a specific motion pattern of each of the one or more gestures captured from the one or more gesture windows; applying, at least one of (i) a positive or (ii) negative time delay to each of the plurality of sub-shapelets of the one or more gestures to obtain a plurality of composite shapelets for the one or more gestures, wherein the plurality of composite shapelets for the one or more gestures are obtained by using superimposition of positive and negative time delayed sub-shapelets, wherein the positive or negative time delay is provided to each of the sub-shapelets of the one or more gestures based on a displacement and a time pattern of the one or more gestures; and performing, a mapping of each of the plurality of composite shapelets with a plurality of trained shapelets stored in a system database to recognize the plurality of gestures comprised in the one or more activities being performed by the subject. obtaining, using a radar system, a plurality of time domain signals reflected by a subject performing one or more activities; identifying, one or more gesture windows in the plurality of obtained time domain signals, by applying one or more signal properties on the plurality of obtained time domain signals to detect a no motion region and a motion region in the plurality of obtained time domain signals, wherein width of each gesture window is indicative of a time duration in which a gesture is performed, and wherein the one or more gesture windows are identified by eliminating a portion of the plurality of obtained time domain signals with no motion; obtaining, using a spectrogram, one or more shapelets of one or more gestures captured from the one or more gesture windows; creating a dictionary of basic shapelets of one or more motion patterns of a plurality of gestures comprised in the one or more activities performed by the subject; decomposing, using the created dictionary of basic shapelets, the one or more shapelets to obtain a plurality of sub-shapelets of the one or more gestures captured from the one or more gesture windows, wherein each sub-shapelet is representative of a specific motion pattern of each of the one or more gestures captured from the one or more gesture windows; applying, at least one of (i) a positive or (ii) negative time delay to each of the plurality of sub-shapelets of the one or more gestures to obtain a plurality of composite shapelets for the one or more gestures, wherein the plurality of composite shapelets for the one or more gestures are obtained by using superimposition of positive and negative time delayed sub-shapelets, wherein the positive or negative time delay is provided to each of the sub-shapelets of the one or more gestures based on a displacement and a time pattern of the one or more gestures; and performing, a mapping of each of the plurality of composite shapelets with a plurality of trained shapelets stored in a system database to recognize the plurality of gestures comprised in the one or more activities being performed by the subject.