Optimized digital radio over fiber system for medium range communication

In recent years, the demand of efficient and broadband wireless access has escalated, for which Radio over Fiber (RoF) is considered as an appropriate solution. In this paper, we present a Digitized Transmission of 20 MHz LTE signal having 64 quadrature amplitude modulation over 70 Km of Standard Single Mode Fiber (SSMF) for broadband wireless signal transportation and distribution applications. The performance analysis has been evaluated for conventional Analog Radio over Fiber (A-RoF) and proposed Digital Radio over Fiber (D-RoF). The bandpass sampling technique is discussed and employed for digitizing the RF signal. As a figure of merit, the performance evaluation of two architectures is reported by analyzing the Error Vector Magnitude (EVM), Signal to Noise Ratio and Eye-Opening Penalty. It is shown that digital optical links can mitigate the impairments present in A-RoF links and can support the transmission up to 70 Km. Moreover, it is shown that efficient D-RoF links can be obtained with a relatively low amount of analog to digital converter (ADC) resolution bits. An experimental validation of the proposed analytical D-RoF model is done for 30 Km of SSMF, whose experimental results are in line with the analytical ones. The evaluated parameters are within the LTE specifications, proving this is a cost and power effective solution for next generation wireless networks