Codeword Position Index based Sparse Code Multiple Access System

In this letter, a novel variation of sparse code multiple access (SCMA), called codeword position index based SCMA (CPI-SCMA), is proposed. In this scheme, the information is transmitted not only by the codewords in M point SCMA codebook, but also by the indices of the codeword positions in a data block. As such, both the power and transmission efficiency (TE) can be improved, moreover, CPI-SCMA can achieve a better error rate performance compare to conventional SCMA (C-SCMA).