Impact of Overloading Factor on MIMO–SCMA Systems

Sparse code multiple access with multiple-input multiple-output (MIMO–SCMA) is one of the technical schemes proposed for 5G communication systems. One of the challenges in 5G network is massive connectivity regarding the number of devices and data volume without spectrum increase. In the SCMA structure, each allocated resource can be accessed by several users at the same frequency and time, which is called the overload factor. This paper investigates MIMO–SCMA performance with various overload scenarios under Rayleigh and AWGN channel models. For single SCMA and MIMO– SCMA with an increased overloading factor up to 300%, the result shows that the processing time significantly increases, and the bit error rate performance is underperformed. However, MIMO-SCMA performance is outperformed others in bit error rate, but processing time complexity is still higher than single SCMA.