An ultra-wideband orthogonal frequency division multiplexing system (UWB-OFDM) may be an ideal transmission/access solution for short-range

high data rate

wireless networks.As the occupied bandwidth increases

however

its implementation becomes more and more difficult.To solve this problem

we investigate a few of typical implementation structures

frequency-domain direct spreading (FDDS)

multi-branch diversity (MBD)

multi-branch frequency-domain equalization (MBFDE)

double-layer multi-carrier frequency division multiplexing (DLMC-FDM)

double-layer multi-carrier frequency diversity (DLMC-FD)

double-layer multi-carrier frequency-hopping (DLMC-FH)

and their combinations

for UWB-OFDM systems.The analysis focuses on the characteristics of each structure and the relationship between any two structures.The findings try to provide a theoretical foundation for the design of UWB-OFDM systems.