As the demand of mobile device increases, there are a large number of researches for more efficient and convenient mobile systems. Especially reducing energy consumption is one of the main subjects for the embedded system. Particularly, $\emph{dynamic voltage scaling}$ has been proposed to reduce the energy consumption of the most energy consumed components in the whole system.
In this thesis, we will use MPEG decoder for workload due to a lots of multimedia application usage on the mobile devices. For power measurement, $\emph{Wattch}$ simulator based on $\emph{SimpleScalar}$ instruction set simulator is used and MPEG decoder is running on this simulator. $\emph{Dynamic voltage scaling}$ is applied to $\emph{SimpleScalar}$ architecture using the difference of workloads between frames in MPEG stream. The energy reduction of processor can be expected by this simulation. As a result, there is about 70% ~ 85% energy reduction with $\emph{DVS}$ per frame unit.