The basic architecture of the human activity monitoring system can be represented with the help of a block diagram; the simplest one is shown in Figure 1. Depending on the task of monitoring, different types of sensors are used. The raw data from sensors are collected by a processor. The data are processed and then displayed on a display. These types of simple wearable devices are used by normal people while jogging, running and other applications where the users look at the display to notice the measured values of the sensors. If the device has the feature of wireless data transmitting capability, the data can be sent to a central station through a transceiver. The block diagram representation of a simple wearable wireless device is shown in Figure 2. The data may or may not be completely processed at the sensing end but most of the data are stored, processed in the computer