Architectural enablers and concepts for mm-wave RAN integration

The following white paper discusses key architectural aspects of the mm-wave RAT (Radio Access Technology) working in frequency bands from 6 GHz to 100 GHz integrated with new and other legacy technologies. Five architectural enablers were identified. The first enabler is multi-connectivity that allows the integration of mm-wave technology with low-band system and contributes for the improvement both in terms of reliability and performance. Second key enabler is a new mobility state, namely RRC_INACTIVE, which helps protect system from extensive signalling related to infrequent small packet data transmissions. The third enabler is mm-wave cell clustering, rendering a solution for dealing with propagation blockages and frequent changes of the serving access point. Mm-wave cell clustering helps to perform cell switching in a rapid fashion without introducing overwhelming amount of signalling towards the core network. A fourth enabler is network slicing, which will allow multiple logical networks to share a common physical infrastructure. The last enabler is self-backhauling which, when coping with ultra-dense and cost-effective deployments, is the best transport network solution in this scenario at the moment of writing. Apart from these key enablers, we present new network functions that bring significant benefits to mm-wave system operation. These functions are: power efficiency oriented KPIs, upper layer optimizations for mobility; reference signal design to support active mode mobility in beam-based Radio Access Network (RAN); low frequency-assisted initial access beam training; user position prediction; user localization; and environment mapping to improve mobility.?