New Radio 5G User Plane Design Alternatives: One 5G Air Interface Framework Supporting Multiple Services and Bands

The standardization of 5G, referred to as new radio (NR), has started. The 5G air interface (AI) is envisioned to comprise a number of AIs including the evolution of Long Term Evolution (LTE) and new NR AIs operating at frequencies from below 1GHz and up to 100GHz. One of the key challenges is the design of an overall 5G AI that efficiently combines these AIs into one 5G AI framework. This paper examines how the AIs can be harmonized into a single 5G AI framework, while minimizing the complexity of standardization and implementation. The harmonization among the 5G AIs could take place at any layer: at the physical layer (PHY), at the Medium Access Control layer (MAC) or at the Packet Data Convergence Protocol (PDCP) layer. Among various detailed harmonization options that are being investigated in this context, for the integration of the new AIs at the physical layer, cyclic prefix-orthogonal frequency division multiplexing (CP-OFDM) waveform with various numerologies is considered as a basis and the MAC layer harmonization can be built on top of the PHY layer, where the CP-OFDM-related AIs of different numerologies are catered for different future services, bands, and cell types. Also, harmonization at the PDCP layer appears to be the most viable harmonization option between the evolved LTE and the new AIs. The results of the first conducted 5G AI analysis will constitute discussion topics for other 5G-PPP projects as well as 3GPP.