This paper studies the feasibility of using UML in Software Defined Radio (SDR). The contributions of the study are in three areas:
1. SDR is used as an example to elaborate the UML for hardware software co-design in embedded communication system. A hybrid UML design approach for the SDR open architecture, SCA, is elaborated in the paper.
2. Some compiler design techniques are also elaborated. The integration and mapping of UML with other languages e.g. VHDL in the system design and hardware software is discussed as well.
3. Some extensions for UML are proposed for the real time embedded system, especially SDR.