Conditional dual‐connectivity decoupling design framework for OMA and NOMA heterogeneous networks and performance comparison

Abstract

In order to enhance simultaneously the association robustness of mobile users and spectrum efficiency (SE) of systems, by integrating the decoupled uplink (UL)/downlink (DL) association (DUDA) and cross-tier dual connectivity (DC), the orthogonal multiple access (OMA)-mode and non-OMA (NOMA)-mode design schemes are investigated over a three-tier heterogeneous network (HetNet) accompanying with the proposition of a conditional association analysis method. The scheme exploits effectively the DC requirement of NOMA. Additionally, in the proposed conditional association design and analysis method, the decoupling UL association designs are conducted only under a given DL association condition. Owing to low complexity, this method shows that it is very easy to achieve the possible decoupling UL DC designs and the corresponding condition association probabilities. Then, the conditional coverage probabilities and SEs of the OMA-mode and NOMA-mode HetNets are derived by specially considering DUDA and coupled UL/DL association strategies. The proposed conditional design framework can be easily extended to multi-tier HetNets and is helpful to select feasible DL candidate from all possible DL associations so that the resulting UL associations are optimal. Besides this, the cross-tier DC design ensures the effective exploitation of the whole network resources because different tiers have different serving levels.