Terrestrial digital multimedia broadcasting system can provide higher data rate per radio channel and more flexible in handling of data services than analog systems, but still, it is not enough to provide sufficient and flexible data transmission capability for the future needs such as high quality video service and real time traffic information service including various location based applications. This thesis will, after examining the requirements of the future T-DMB services, study the possible enhancement methods to satisfy these requirements. The ``requirements`` include rich-media applications based on higher data rate delivery capability, more efficient data multiplexing with increased use of interactive network, and finally, backward compatibility issues to maintain the existing T-DMB systems and services. Two kinds of enhancement method were considered in this thesis introducing hierarchical modulation and super-block scheme. The hierarchical modulation is done by over modulating the basic modulated symbols with another modulation scheme. To analyze the effects of hierarchical modulation, this thesis derived some analytic approximate result and applied this approximation to one of the real systems to obtain different coverage. The super-block scheme is the extension of the transmission bandwidth toward 6 MHz by using all the sub-carriers of three blocks and their guard bands assigned in between them. The designand usage of the additional parameters needed for the increased bandwidth system has been analyzed and the draft result are proposed. All these extensions will include the precondition that they should provide the method of backward compatibility with existing systems. Thus, they can be used as the basic methods for enhancing the T-DMB system toward the future wideband mobile broadcasting system.