Abstract-- Future (5G) mobile networks aim to pervasivity (cell size  20-50 Mb/s), centralized radio access network (CRAN) is the most promising paradigm that aggregates the baseband processing to comply with dense antennas deployment. Even if optical networks are the most promising solution for CRAN front-hauling, there is the need to investigate alternative and/or complementary solutions to digital front-hauling (e.g., CPRI protocol) that can make a parsimonious usage of the optical bandwidth and related electronics. Abstract-- In this framework, here we propose a new waveform coding for the transport of analog RAN signals by employing the pulse width modulation (PWM) for optical front-hauling. At the transmitter, the radio-signal is sampled and mapped onto the duration of an on/off optical signal, at the fiber receiving-end each PW optical modulated sample is digitized so that the overall communication is transparent. Conceptually, the front- hauling PW waveform is equivalent to split sampling (at transmitter) and quantization (at receiver) so as to avoid the bandwidth expansion of CPRI digitalization. Pros and cons of PW waveforms for CRAN front-hauling are evaluated by investigating the outcomes of an in-lab experiment transmitting 100-MHz RF signals with 16QAM modulation up to 20-km standard single mode fiber. Experimental results provide some room for discussion on this novel front-hauling technique.
['Lorenzo Combi', 'A. Gatto', 'Mario Martinelli', 'Paola Parolari', 'Umberto Spagnolini']
Pulse-Width Optical Modulation for CRAN Front-Hauling