User Plane Radio Protocol Concepts for $\mathbf{6 G}$

In the user plane, the role of radio protocols to reliably convey data packets over the physical radio channel, is key also in 6G. In each 3GPP generation they evolved, incorporating an increasing number of variants of the radio access network (RAN) architectures and target use-cases. This added complexity, but also reduced their processing efficiency. For 6G, we revisit these shortcomings and propose a leaner protocol stack capable of achieving the same functionality in a more processing and latency efficient way. We show how to design a simplified uplink control structure and reduce uplink access latency, how to optimize hybrid automatic repeat request (HARQ) in terms of reliability, and how this information can be exploited at higher layers, enabling the introduction of a unified 6G radio bearer protocol (RBP).