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The sparse code multiple access (SCMA) is one of the promoting candidate of code-domain non-orthogonal multiple access (CD-NOMA) for the upcoming generations of wireless communications systems, and it has been actively investigated in recent years. The key distinguishing feature of SCMA comes from the gain of its multi-dimensional sparse codebooks. Nevertheless, all users have not the same business requirements, and their physical layer needs depend on many factors such as the maximum allowed delay, the required rate and the targeted quality of service. In this paper, an adaptive SCMA scheme is proposed to tackle this problem. The idea is to divide users into different groups such as an adaptive designed codebook is allocated to each group. Unlike the traditional SCMA, the sparsity degree, the constellation size, and the allocated power per user, can be adapted to each group requirements in order to increase the overall performance of an uplink SCMA system. Simulation results show that the proposed scheme outperforms the traditional regular SCMA.
