SPREADING/DESPREADING SYSTEM AND METHOD IN MC-CDMA

摘要

PURPOSE: A spreading/despreading system and method in an MC-CDMA(Multicarrier-Code Division Multiple Access) are provided to easily implement two-dimensional time/frequency spreading and variable spread rate of a direct spreading/despreading and multicarrier spreading/despreading. CONSTITUTION: A symbol repeating unit repeats each symbol of a modulation symbol stream inputted for spreading during a process of forming a signal of MC-CDMA as many as the repetition number(R) which is determined according to a variable spread rate. A spreading unit directly spreads the repeated symbols by using a spread code having the same chip rate as the symbol rate, and a demultiplexer separates the spread symbols to parallel chip streams as many as the multicarrier through serial/parallel conversion by a serial/parallel converter(52). An inverse frequency converter carries each separated chip on corresponding subcarriers and transmits it to a receiving side through an IFFT(Inverse Fast Fourier Transform) by an IFFT(Inverse Fast Fourier Transform) unit(53).