On the optimal Space-Frequency to Frequency mapping in indoor single-pair RoC fronthaul

Centralized Radio Access Network (C-RAN) architecture is the enabling technology for the deployment of massive number of antennas essential to meet the requirements of next generation (5G and beyond) mobile systems. In C-RAN the fronthaul links between processing Base Band Units (BBUs) and Remote Antenna Units (RAUs) are conventionally based on fiber optic, although its deployment cost can be excessive. Radio over Copper (RoC) is an alternative/complementary technology for the fronthauling especially suitable for self-powered indoor deployment since it leverages on the pre-existing LAN cables. In this paper we consider a RoC C-RAN architecture as a low-cost bandwidth-efficient in-building solution to guarantee enhanced indoor coverage as required by 5G and beyond mobile systems. In particular, the focus of the paper is to gain insights into the optimal resource allocation to/from the RAU equipped with multiple antennas or multiple radios (e.g., 5G and WiFi) and the cable resources to fully exploit the capabilities of the twisted-pair cable over the last 50-100m. Numerical results validate the proposed method considering a realistic radio environment where the performance of indoor users are impaired by the interference of outdoor non-cooperating cells.