I. Introduction
The opportunity for multi-Gb/s wireless communication at mm-wave frequencies comes with many technical challenges due to the high carrier frequencies and the wide channel bandwidths used [1]–[4]. These include the significantly higher air-link loss at mm-wave frequencies (e.g., path loss at 60 GHz is about 30 dB higher than at 2.4 GHz), and reduced device performance and lower power efficiency. These and other factors cause mm-wave wireless networks to have significantly reduced cell coverage ( m), a high density of antenna units, and an extensive high-capacity feeder network. Mm-wave wireless networks can, therefore, benefit from Radio over Fiber (RoF) technology, which takes advantage of the high-bandwidth fiber-based feeder network to significantly simplify remote antenna units (RAUs) [5] while supporting multistandard system operation (e.g., single-carrier or OFDM signal modulation) [6]. However, most of the proposed RoF systems for mm-wave applications employ complex system architectures based on optical frequency up-conversion [7]–[9] in order to deal with the challenging requirements for the transmission and generation of high data-rate wireless signals at high carrier frequencies [10].