Abstract-Sparse code multiple access (SCMA) is a promising air interface candidate technique for next generation mobile networks. By introducing the Tent map in the Chaos theory, we propose a novel physical layer transmission scheme with codeword level interleaving at the transmitter in this letter, which is termed as interleaver based SCMA (I-SCMA). Simulation results and analysis show that I-SCMA can provide high security performance without any loss in performance and transmission rate, thus constitutes a viable solution for the next generation wireless networks to provide secure communications.