We propose a wearable sensor system, which consists of a two-axis accelerometer and RF wireless communication modules. The acquired body motion signals from accelerometers are transmitted to a host computer via RF link for
feature extraction and pattern recognition. Wavelet transform techniques are adopted for feature extraction of human body postures. The signal is decomposed into five levels and low-frequency components are extracted to obtain useful features. Pattern recognition techniques are then applied to distinguish five basic postures: up stairs, down stairs, walking, standing, and sitting. Experimental results are presented to show the effectiveness of the proposed method.