Frequency Hopping Non-Orthogonal Multiple Access.

Non-orthogonal multiple access (NOMA) has circumvented OMA’s connectivity limitations, providing new possibilities to achieve a larger connection. One of the most popular uplink NOMA schemes is sparse code multiple access (SCMA). Massive research has been made on SCMA, which focuses on the codebook design and low complexity multi-user detector (MUD). We are interested in how to maximize the connectivity ability of code domain NOMA with tolerable complexity of the receiver. In this paper, a frequency hopping (FH)-based NOMA is proposed. Under this scheme, the spreading factor (SF) is reduced to one to accommodate a larger connection. The system adopts frequency hopping technique to increase the system diversity and promote extrinsic information interaction between users. A heuristic frequency hopping sequence allocation method is proposed , which succeeds in uniformly transmitting users’ signals on the resource block. Simulation results verify the effectiveness of the proposed scheme. And we notice that FH-NOMA is more adaptable to non-ideal channels. Experiments show that FH-NOMA has superior performance than SCMA under higher user load and higher spectral efficiency requirements.