Power-imbalanced multi-level decoding method and system for sparse code multiple access

A power-imbalanced multi-level decoding system for SCMA, comprising:

• a transmitter;
• a Rayleigh fading channel;
• and
• a receiver;
• the transmitter is configured for mapping information bits of all users to multi-dimensional sparse codewords via predetermined codebooks;
• constructing a factor graph matrix using each predetermined codebook, and classifying all users into L levels based on the factor graph matrix under a predetermined constraint, wherein L is a positive integer greater than 1;
• based on a predetermined total transmission power, performing a power-imbalanced allocation for all users according to the L levels using a progressive multi-level power optimization algorithm to determine a locally optimal power vector;
• the Rayleigh fading channel is configured for transmitting a transmission signal corresponding to the multi-dimensional sparse codewords according to the locally optimal power vector;
• and
• the receiver is configured for sequentially performing a power-oriented decoding for users of each level, and outputting decoded bit sequences for the L levels.