Downlink PDMA in the Heterogeneous Network

Non-orthogonal multiple access (NOMA) is considered as a promising multiple access technology, which could satisfy various incremental requirements of the coming fifth generation (5G) mobile communication system. As a novel NOMA scheme based on the joint design of the transmitter and receiver, pattern division multiple access (PDMA) could enhance spectrum efficiency significantly, compared to traditional orthogonal multiple access (OMA) schemes. In this paper, a particular pattern design of downlink PDMA in heterogeneous network is proposed. In overlapping deployment scenario of macro cells and small cells, the downlink signals are transmitted with a novel spatial and power domain superposition pattern. The user pairing and spatial/power allocation schemes are therefore proposed optimizing the pattern design. Analysis and simulation results illuminate the pattern design of downlink PDMA could enhance the spectrum efficiency obviously.