## 3 System Setup  
The IM-DD optical link used to elaborate the proposed A-RoF architecture that can be implemented in the dense wavelength multiplexed passive optical networks (wavelength division multiplexer (WDM)/passive optical network (PON)) infrastructure is shown in Figure 1. The emulated optoelectronics devices parameters are taken from the experimental demonstration reported in the work of [10]. At the transmitter side, the digital-to-analogue converter (DAC) is modelled with a sampling rate of 12-GSa/s and vertical resolution of 10 bits. It is used to convert the offline generated DSP waveforms in Matlab(r) based on either FDMA or TDMA aggregation schemes to analogue signal. The driver is used to drive the electrical analogue signal to the external Mach-Zehnder modulator (MZM) radio frequency (RF) input. The external MZM is modelled using the following  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**SCs Type** & \begin{tabular}{c} **SCs** \\ **[KHz]** \\ \end{tabular} & \begin{tabular}{c} **Cyclic Prefix** \\ **symbols** \\ \end{tabular} & \
\begin{tabular}{c} **Maximum** \\ **bandwidth [MHz]** \\ \end{tabular} &
\begin{tabular}{c} **Sampling rate** \\ **[MSa/s]** \\ \end{tabular} \\ \hline
0 & 15 & 144 & 50 & 61.44 \\
1 & 30 & 144 & 100 & 122.88 \\
2 & 60 & 144 & 200 & 245.76 \\
3 & 120 & 144 & 400 & 491.52 \\ \hline \hline \end{tabular}
\end{table}
Table 1: New radio (NR) parameter based on type of spacings (SCs).  
parameters: extinction ratio (ER) = 27.8 dB, insertion loss (IL) = 1.8 dB, \(V_{\pi}\) radio frequency (RF) electrode voltage = 3.0 V, direct current (DC) bias voltage = \(V_{\pi}/2\) V, and modulation index M = 100 %. It is used to modulate the continuous wave (CW) optical carrier. The CW laser source is assumed to be phase and amplitude noiseless, and is capable of generating CW lasers at different wavelengths, spaced by 100 GHz. WDM is used to select the desired single wavelength, for instance, filter \(\lambda\)1 operating at a wavelength of 1550.92 nm. The instantaneous optical signal at the output of the external MZM is then amplified by the erbium doped fiber amplifier (EDFA), which is used to maintain the average transmitted output optical power to a fixed value. The optical channel is realized by considering the optical signal propagation into standard single mode fiber (SSMF), characterized by having a chromatic dispersion CD = 17 \(ps/mm.km\) and length L = 25 km. The optical channel targeting low-cost optoelectronics, the overall electrical-to-electrical transfer function, has a pole at 5 GHz that is is emulated by a fourth order Bessel filter. A variable optical attenuator (VOA) is used to control the optical distribution network (ODN) loss of the link. At the receiver side, the avalanche photodetector (APD) that is typical of the next generation passive optical networks (NG-PON2) architecture is modelled by assuming that the noise contribution arises from Gaussian amplified shot noise, receiver electrical thermal noise in the receiver circuitry, and dark current noise, which are independent and identically distributed [11]. The analogue-to-digital converter (ADC) is modelled using eight quantization bits [12]. The transmitter (TX) and receiver (RX) digital signal processing (DSP) functionalities of FDMA and TDMA approaches are represented by the block diagrams shown in Figures 2 and 3, respectively, and are described in the following subsection.  
Figure 1: Intensity modulation and direct detection (IM-DD) analogue radio-over-fiber (A-RoF) model. Transmitter side consisting of transmitter digital signal processing (TX DSP), digital-to-analogue converter (DAC), continuous wave (CW) laser, wavelength division multiplexer (WDM) electrical driver, and external Mach–Zehnder modulator (MZM). The optical channel consists of a standard single mode fiber (SMF) and variable optical attenuator (VOA). The receiver side consists of avalanche photodetector (APD), analogue-to-digital converter (ADC), and receiver digital signal processing (RX DSP). ODN—optical distribution network.