Non-orthogonal transmission for user and control plane split architecture in 5G systems and beyond: Performance analysis and design insights

In next generation networks, mobility management will be a critical issue due to dense base station (BS) deployment, for which user and control plane split architecture provides a promising solution. Jointly designing such architecture with nonorthogonal transmission brings in more flexibility to further improve system efficiency. This paper proposes a non-orthogonal transmission design for user and control plane split architecture. In this design, user equipments (UEs) will select the BS providing the strongest received signal to associate its data channel, but constantly connect its control channel to the nearest macro-cell BS (MBS). Upon non-orthogonal transmission, an MBS can multiplex data traffics and control signals on the same resource. Stochastic geometry based analysis is carried out to investigate outage probability, which extends its regular definition by jointly considering data and control channels, and then mobility-aware outage rate. Numerical results show that: 1) The proposed split architecture alleviates the increase in handover rate for ultra dense networking, compared with conventional architecture. 2) Non-orthogonal transmission outperforms traditional orthogonal transmission in the split architecture, because it is capable of accommodating more control channels. 3) By carefully adjusting power levels, minimum outage probabilities can be reached for macro-cell UEs in the proposed design.