THE STUDY OF AN M-ARY MC-CDMA SYSTEM BASED ON CYCLIC SPREADING CODES & PRE-EQUALIZATION

A novel fast despreading scheme for M-ary Multi-Carrier Code-Division Multiple Access (MC-CDMA) system is proposed based on cyclic spreading codes and pre-equalizer. In the transmitter, the M spreading codes of each user are generated by circularly shifting the prototype spreading code. A feedback pre-equalizer is employed to process the M-ary MCCDMA signal before transmitted. The received signal is multiplied by the Inverse Discrete Fourier Transform (IDFT) result of the mirror image code of the prototype spreading code, and then demodulated by Orthogonal Frequency-Division Multiplexing (OFDM) demodulator. Compared with the conventional M-ary MC-CDMA receiver, the proposed scheme increases bandwidth efficiency, meanwhile, it achieves M-ary despread spectrum and multi-carrier demodulation, which reduces computation complexity remarkably.     

THE STUDY OF AN M-ARY MC-CDMA SYSTEM BASED ON CYCLIC SPREADING CODES ＆ PRE-EQUALIZATION

A novel fast despreading scheme for M-ary Multi-Carrier Code-Division Multiple Access (MC-CDMA) system is proposed based on cyclic spreading codes and pre-equalizer. In the transmitter, the M spreading codes of each user are generated by circularly shifting the prototype spreading code. A feedback pre-equalizer is employed to process the M-ary MCCDMA signal before transmitted. The received signal is multiplied by the Inverse Discrete Fourier Transform (IDFT) result of the mirror image code of the prototype spreading code, and then demodulated by Orthogonal Frequency-Division Multiplexing (OFDM) demodulator. Compared with the conventional M-ary MC-CDMA receiver, the proposed scheme increases bandwidth efficiency, meanwhile, it achieves M-ary despread spectrum and multi-carrier demodulation, which reduces computation complexity remarkably.     

A scheme of m -ary multi-carrier spread spectrum based on wavelet packet

A novel scheme of M-ary multi-carrier spread spectrum based on wavelet packet is proposed. Its performance is investigated for a multipath, slow Rayleigh fading channel. The performance advantages of the system over that based on DFT are demonstrated by both analytical and simulation methods. Supported by the National Natural Science Foundation of China (No.60172029)     

Two-dimensional multiplicative arrays over Zq−1 and girth-6 q-ary QC-LDPC codes based on quadratic-residues modulo p < q

Construction of q-ary quasi-cyclic low-density parity-check (QC-LDPC) codes based on two-dimensional multiplicative arrays over Z_q−1, q = 2^m, is studied. In particular, two-dimensional arrays formed by the set of quadratic-residue numbers modulo prime numbers less than q are considered.