Contents Introduction
Radio-over-Fibre (RoF) distribution antenna systems have been identified as a flexible option for the access architecture of the emerging wireless access networks, especially inside buildings, as a means of reducing infrastructure cost and antenna site (AS) complexity. Whereas direct modulation of lasers with the RF signals is the most common method to reduce cost and complexity in radio standards below 5GHz, for the emerging broadband wireless systems, operating at higher frequencies, the main challenge is the generation and delivery of microwave signals to the AS, while maintaining the link simplicity. Additionally, and, as a further step towards a reliable RoF infrastructure for broadband wireless access, other networking aspects, like the support of multiple wireless standards and dynamic radio link adaptation, have to be considered. Among many different RoF techniques, Optical Frequency Multiplication (OFM) [1], based on harmonics generation by frequency modulation to intensity modulation (FM-lM) conversion, has the advantage of generating microwave carriers with one single laser source and low frequency electronics. In this article, we propose a RoF physical layer design exploiting this technique, which comprises bidirectional RF transmission, increased cell capacity allocation, multi-standard support, remote LO delivery and an in-band control channel for dynamic radio link adaptation and remote antenna controlling. We also present some engineering rules based on our experimental results.
