Heterogeneous Networks with Power-Domain NOMA: Coverage, Throughput and Power Allocation Analysis

摘要

In a heterogeneous cellular network (HetNet), consider that a base station inthe HetNet is able to simultaneously schedule and serve K users in the downlinkby performing the power-domain non-orthogonal multiple access (NOMA) scheme.This paper aims at the preliminary study on the downlink coverage andthroughput performances of the HetNet with the non-cooperative and the(proposed) cooperative NOMA schemes. First, the coverage probability and linkthroughput of K users in each cell are studied and their accurate expressionsare derived for the non-cooperative NOMA scheme in which no BSs are coordinatedto jointly transmit the NOMA signals for a particular user. We show that thecoverage and link throughput can be largely reduced if transmit powerallocations among the K users do not satisfy the constraint derived. Next, weanalyze the coverage and link throughput of K users for the cooperative NOMAscheme in which the void BSs without users are coordinated to enhance thefarthest NOMA user in a cell. The derived accurate results show thatcooperative NOMA can significantly improve the coverage and link throughput ofall users. Finally, we show that there exist optimal power allocation schemesthat maximize the average cell coverage and throughput under some derived powerallocation constraints and numerical results validate our analytical findings.