In view of the realization of short and medium range Mobile Front Haul (MFH) connections for present (LTE) and future (5G) cellular networks, a cost effective, low consumption Radio over Fiber system is proposed, based on 850 nm Single Mode Vertical Cavity Surface Emitting Lasers (VCSELs) and Standard Single Mode Fibers (SSMFs). An efficient countermeasure to possible impairments due to the bi-modal behavior of SSMFs at 850 nm allows even in critical cases to maintain at high level the quality of the received signal. The performances are evaluated with reference to the Physical Downlink Shared Channel of an entire LTE frame with 20 MHz bandwidth centered in band 20 of the standard. In terms of Error Vector Magnitude and outage probability under temperature stress the system is able to transmit 256-QAM signals in compliance with the LTE standard, which corresponds to a raw data rate transmission of 134.4 Mbit/s, up to distances of 1.5 Km.

The design and development process for the Square Kilometre Array (SKA) radio telescope’s Low Frequency Aperture Array component was progressed during the SKA pre-construction phase by an international consortium, with the goal of meeting requirements for a critical design review. As part of the development process a full-sized prototype SKA Low ‘station’ was deployed – the Aperture Array Verification System 1 (AAVS1). We provide a system overview and describe the commissioning results of AAVS1, which is a low frequency radio telescope with 256 dual-polarisation log-periodic dipole antennas working as a phased array. A detailed system description is provided, including an in-depth overview of relevant sub-systems, ranging from hardware, firmware, software, calibration, and control sub-systems. Early commissioning results cover initial bootstrapping, array calibration, stability testing, beam-forming, and on-sky sensitivity validation. Lessons learned are presented, along with future developments.

This paper investigates the possibility of implementing SiGe Hetero-junction bipolar Photo-Transistor (HPT) within low cost and low power consumption Radio-over-Fiber (RoF) systems based on Standard Single Mode Fiber (SSMF) operating in the first optical window for wireless communication networks scenarios. The SiGe HPT under study has potential lower cost compared to standard PIN photo-detectors as it is fabricated through the consolidated SiGe bipolar transistor process technologies, allowing the possible integration with Sibased circuits. Various operation modes of the photo-transistor (such as three-terminals and two-terminals) are investigated, analyzing their impact on the SSMF-based RoF link in terms of gain and noise (including modal noise fluctuations) for a frequency range up to 2.5 GHz. A 20 MHz LTE transmission is finally demonstrated as example of possible applications of the studied RoF link.

Radio over Fiber (RoF) Systems exploiting a direct modulation of the laser source are presently utilized within important Radioastronomic scenarios. Due to the particular operating conditions of some of these realizations, the phenomena which typically generate nonlinearities in RoF links for telecommunications applications can be here regarded as substantially harmless. However, these same operating conditions can make the RoF systems vulnerable to different kinds of nonlinear effects, related to the influence of the Rayleigh Backscattered signal on the transmitted one. A rigorous description of the phenomenon is performed, evidencing its possible impact also within other applicative contexts, and an effective countermeasure to the problem is proposed and demonstrated, both theoretically and experimentally.

Sigma Delta Radio over Fiber (S-DRoF) systems are looked upon as an enabling technology due to their advantages that comes due to combination of analog and digital radio over fiber (RoF) systems. In this paper, we have proposed and experimentally demonstrated a Multi-stAge-noise-SHaping (MASH) based Sigma Delta Modulated RoF system targeting 5G C-RAN (cloud/centralized radio access network) fronthaul applications. The evaluation has been done for LTE 20 MHz signal having 256 quadrature amplitude modulation with a carrier frequency of 3.5 GHz up to 5 Km of Standard Single Mode Fiber (SSMF). Furthermore, a comprehensive analysis of the design is explained followed by the experimental setup. The performance is reported in terms of error vector magnitude (EVM) and adjacent channel leakage ratio. It is concluded that S-DRoF substantiates the desired range of the 5G C-RAN fronthaul networks.

Harmonic and intermodulation distortion contributions generated by modal noise in radio over multimode fiber (RoMMF) systems for in-building wireless coverage are reviewed. The role played by the launching technique and by the optical transmitter and receiver in an intensity-modulated direct-detection RoMMF system is described theoretically and experimentally. The presented results constitute a basis for the design of multiband RoMMF systems, where spurious emission due to distortions should be compliant with wireless standards both in downlink and uplink.