  Most of the indoor coverage issues arise from network deployments that are
usually planned for outdoor scenarios. Moreover, the ever-growing number of
devices with different Radio Access Technologies (RATs), expected for new 5G
scenarios and to maintain compatibility with older cellular standards (mostly
3G/4G), worsen this situation thus calling for novel bandwidth-efficient,
low-latency and cost-effective solutions for indoor coverage. To solve this
problem, Centralized Radio Access Network (C-RAN) architectures have been
proposed to provide dense and controlled coverage inside buildings. However,
all-digital C-RAN solutions are complex and expensive when indoor layout
constraints and device costs are considered. We discuss here an analog C-RAN
architecture, referred to as Analog MIMO Radio-over-Copper (A-MIMO-RoC), that
aims at distributing RF signals indoors over distances in the order of 50 m.
The all-analog passive-only design presented here proves the feasibility of
analog relaying of MIMO radio signals over LAN cables at frequency bandwidth
values up to 400 MHz for multi-RAT applications. After asserting the
feasibility of the A-MIMO-RoC platform, we present some experimental results
obtained with the proposed architecture. These preliminary results show that
the A-MIMO-RoC system is a valid solution towards the design of dedicated 4G/5G
indoor wireless systems for the billions of buildings which nowadays still
suffer from severe indoor coverage issues.
