Interference Suppressed NOMA for Semantic-aware Communication Networks

In this paper, we propose a novel interference-suppressed semantic-aware non-orthogonal multiple access (IS-SNOMA) framework for downlink image transmission in the semantic-aware communication networks. The proposed IS-SNOMA is able to mitigate the inter-user interference in the non-orthogonal transmission for multiple semantic-oriented users (SU) or the coexistence of SUs and bit-oriented users (BU). 1) For the homogeneous transmission of semantic streams, we propose a pair of novel semantic difference (SeD) aware IS-SNOMA transceivers to accommodate multiple SUs over the same resource block. A novel SeD-aware superposition coding (SeDSC) technique and SeD-aware successive interference cancellation (SeDSIC) technique are specially designed to mitigate the semantic-level interference. 2) For the heterogeneous transmission of semantic-bit streams, we develop a pair of syntactic difference (SyD) aware IS-SNOMA transceivers to multiplex channels for SUs and BUs. The heterogeneous semantic symbols and bit sequences are superposed and separated with the proposed SyD-aware SC technique (SyDSC) and SyD-aware SIC technique (SyDSIC), respectively. Simulation results demonstrate the advantages of the proposed frameworks in improving the communication efficiency of both SUs and BUs, compared with OMA and NOMA-aided transmission benchmarks.