Coded Orthogonal Frequency Division Multiplexing (COFDM) technology has been widely accepted in many communication systems due to both bandwidth efficiency and robustness to channel distortion. This opens a great of opportunities for SoC society to deal with design complexity by exploiting benefits of giga-scale integration. In this paper, we'll first review the general design concept of COFDM systems and then highlight several key issues in SoC realization. Then a system-level design flow by taking into account both performance indices and hardware complexity will be introduced. Several core modules related to COFDM system will also be addressed to see how better solutions can be achieved, especially for wireless applications. Finally two case studies on WLAN and OFDM-UWB will be discussed to demonstrate our proposals as well as to provide some directions for further research.