A fast OFDM-CDMA user demultiplexing architecture
Document typeConference report
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Rights accessOpen Access
A fast algorithm based on a butterfly structure is presented that demultiplexes the symbols of a particular type of MC-MA (multi-carrier multiple-access) modulation previously proposed for indoor radio communications. A special transform is used to packetize the different symbols on the down-link such that the code sequences associated with the different symbols are transmitted synchronously at the base station. The input to the FFT bins is defined as a symbol-dependent combination of Walsh-Hadamard codes. We derive a fast architecture that can combine the common redundancy found in the Walsh-Hadamard and the inverse Fourier transform. In the direct implementation, the receiver would compute the IFFT (as in OFDM) before the Walsh-Hadamard transform. The proposed algorithm evaluates both transforms in a single step. A general expression for the butterfly weights is derived and the savings in computational complexity in terms of the frame length is evaluated.
CitationMarti, P., Sala, J. A fast OFDM-CDMA user demultiplexing architecture. A: IEEE International Conference on Acoustics, Speech, and Signal Processing. "ICASSP 2000: 2000 IEEE international conference on acoustics, speech, and signal processing: silver anniversary, proceedings: 5-9 June 2000: Hilton Hotel and Convention Center, Istanbul, Turkey". Istanbul: Institute of Electrical and Electronics Engineers (IEEE), 2000, p. 3358-3361.