A Novel Scheme for the Construction of the SCMA Codebook

As a code-domain non-orthogonal multiple access technique, sparse code (SCMA) is considered as promising technique for future wireless Internet of Things (IoT) networks. The minimum Euclidean distance (MED) and product (MPD) have been highlighted the key performance indicators codebook in additive gaussian white noise (AWGN) downlink Rayleigh channels respectively. In this paper, based on mother codebook, novel design scheme proposed to achieve better error both AWGN channels. problem constructing quadratic assignment (QAP), where Tabu searching algorithm employed reduce complexity best permutation result. Then, rotation matrix adopted find degrees generation constellation group, two algorithms are assign obtained factor graph matrix. Taking degree optimization assignments into joint consideration, an improved unified further explored maximize MED each user. Besides, polarized modulation proposed, which places symbols three dimensional (3D) stokes parameters improve system. Finally, simulation results provided show codebooks, comparisons symbol (SER) different codebooks also discussed detail.