Johan Rune

Tight Integration of New 5G Air Interface and LTE to Fulfill 5G Requirements

Integration of new radio technologies to legacy ones has always been an important feature in any wireless communication generation shift and it is envisioned that for the transition to 5G this will be even more critical. Different 5G research projects have acknowledged the demand for a new air interface that will be designed to operate in higher frequency bands (compared to the ones currently allocated to LTE) where propagation is more challenging and coverage is spotty. This paper proposes a radio access network (RAN) architecture that realizes a tight integration of this new air interface with LTE to enable cross-air interface optimizations such as common resource management, faster mobility and simultaneous multi-connectivity features. The tight integration also aims at leveraging both the better coverage of LTE and the higher capacity of the higher frequency bands. In order to realize this integration, a common protocol layer (also called integration layer) lying on the top of lower layer protocols specified per air interface is proposed. The paper analyzes the alternatives for this integration layer, having the LTE protocol stack specified by 3GPP as a reference model. A recommendation is issued and, based on that, potential multi-connectivity features are presented.