Analog RoF Research Articles

Investigation on Transport Schemes for Efficient High-Frequency Broadband OFDM Transmission in Fibre-Wireless Links

This paper investigates the different transport schemes for delivery of high-frequency broadband OFDM signals via fibre-wireless links. We have investigated analog RoF, digitized RoF, and sampled RoF transport schemes and experimentally demonstrated the transmission of broadband RF-OFDM signal using these schemes. Analog RoF results in the simplest BS/RRH configuration but it demands for large optical bandwidth. The performance of this transport scheme is limited by inter-modulation distortion (IMD) and RF power fading. For the digitized RoF transport scheme based on bandpass sampling, although digital optical link is used for signal delivery, the performance is limited by signal clipping and ADC resolution. The sampled RoF transport scheme requires only a narrow optical bandwidth, but the performance is limited by IMD and noise processes introduced by bandpass sampling. Based on our analysis and experimental results, a design guide of fibre-wireless integration system for broadband RF-OFDM transmission is provided. It is found that: analog RoF is best suitable for short-range transmission; digitized RoF has the best performance; and sampled RoF offers a low-cost solution.

Low-Cost Broadband Predistortion-Linearized Single-Drive x-Cut Mach–Zehnder Modulator for Radio-Over-Fiber Systems

We experimentally demonstrate a low-cost broadband predistortion circuit (PDC) for the linearization of a single-drive x-cut Mach-Zehnder modulator (sd-xMZM) in broadband analog radio-over-fiber (RoF) links over 3-5 GHz. By tuning the bias current, the nonlinear characteristic of the PDC can be adjusted to linearize different types of nonlinear components in broadband analog RoF links over 3-5 GHz. By adding the PDC in front of the sd-xMZM, input-refereed 1 dB compression point (P1dB) is improved by 2 dB. By evaluating with the two-tone signal, the PDC allows 14 dB improvement in spurious free dynamic range at 4 GHz, and the third-order intermodulation distortion is suppressed by more than 6 dB over 3-5 GHz. Moreover, the error vector magnitude of an orthogonal frequency division multiplexing ultra-wideband signal is improved by more than 2.5 dB.

Methodological issues in investigations of massage/bodywork therapy. Part II. Making research designs and data credible: model fit validity, combining scientific soundness with the explanatory model of massage and bodywork therapies☆

This work reports the implementation of a multiband 5G new radio (NR) fiber-wireless (FiWi) system, using analog radio over fiber (A-RoF) technology. Our approach employs a 12.5-km optical fronthaul (FH) for transporting fifth-generation of mobile network (5G) signals up to a remote antenna unit, from which 10-m reach wireless transmissions are performed aiming indoor and outdoor enhanced mobile broadband (eMBB) applications. The aforementioned 5G signals refer to a 5G NR standard at 26 GHz with 400-MHz bandwidth and DSP-based flexible-waveform signal at 3.5 GHz from our transceiver, which can be set as orthogonal frequency division multiplexing (OFDM), filtered-OFDM (F-OFDM) or generalized frequency division multiplexing (GFDM). Additionally, an investigation on the coexistence between 5G NR and Long Term Evolution-Advanced (LTE-A) standards in FiWi systems using the 700 MHz band, aimed for long-range applications, is reported. Experimental results demonstrate 1.65 Gbit/s total wireless throughput in accordance with the 3GPP Release 15 root mean square error vector magnitude (EVMRMS) digital performance requirements.