Nonlinear Overlapped Code Division Multiplexing System with High Spectral Efficiency

Improved overlapped code division multiplexing system with high spectral efficiency, called nonlinear OVCDM system, is proposed. Different from linear OVCDM system, the input alphabet of this system belongs to {0,1} and elements in the codeword matrix are real numbers. A nonlinear function and time varying codeword matrix is used to replace linear operation and the time invariant codeword matrix. A method to construct the nonlinear function and time varying codeword matrix is proposed. The simulation results of three NOVCDM systems are all better than linear OVCDM system with same spectral efficiency, additionally, bit error ratio of former two systems is better than low performance limit of ordinary OVCDM system.