Irregular SCMA System for Enhanced Quality of Service

As a scheme of non-orthogonal multiple access in the code-domain, sparse code multiple access (SCMA) is one of the promoting candidate for the upcoming generations of wireless communication systems, and it has been actively investigated in recent years with several challenges about high accuracy codebook design algorithms. Based on the different parameters of SCMA system, for instance, the codebook sparsity degree, we can distinguish two kinds of SCMA system architectures: (i) regular SCMA and (ii) irregular SCMA. In this paper, we investigate first realistic massive communication scenario where, all users have the same channel states but different needs in terms of delay, bandwidth and packet-delivery. However, it is not ideal to equally treat the users when they have different channel states, that may lead to poor quality of service (QoS) for users with bad channel conditions. Motivated by this, we explore new approaches to improve the irregular SCMA structure based on the QoS needed by each user. We propose an optimized irregular SCMA to reply to these needs based on an algorithm of sparsity degree assignment according to the QoS parameters. Simulation results confirms that the different objectives were achieved.