## 2 Literature Review
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**No.** & **Author** & **Type** & **Subcategory** & **Parameter** & **Linearization** & **Pros** & **Disadvantages** \\ \hline
1 & \begin{tabular}{c} [PERSON] et al.; \\ [PERSON] et al. \\ [14, 15] \\ \end{tabular} & Electrical & \begin{tabular}{c} Analog \\ Prediction \\ \end{tabular} & IMD3 & \begin{tabular}{c} Complete RoF \\ system (Laser, \\ photodiode, \\ LNA) \\ \end{tabular} & \
\begin{tabular}{c} Phase maintenance for \\ IMD3 generated \\ components \\ \end{tabular} &
\begin{tabular}{c} Perplexing suppression of second \\ order nonlinear distortion for \\ large bandwidth \\ \end{tabular} \\ \hline
2 & \begin{tabular}{c} [PERSON] et al. [16] \\ \end{tabular} & Optical & \begin{tabular}{c} Mixed \\ Polarization \\ \end{tabular} & \begin{tabular}{c} Second/third \\ order nonlinear \\ distortion \\ \end{tabular} & \begin{tabular}{c} Complete RoF \\ system \\ system \\ \end{tabular} & \
\begin{tabular}{c} Suppression of second \\ and third order \\ nonlinearities \\ \end{tabular} &
\begin{tabular}{c} Rot transmission must be \\ polarization dependent. \\ Compression of linear \\ components to some extent. \\ \end{tabular} \\ \hline
3 & \begin{tabular}{c} [PERSON] et al. [17] \\ \end{tabular} & Optical & \begin{tabular}{c} Dual \\ wavelength \\ linearization \\ \end{tabular} & \begin{tabular}{c} Second/third \\ order nonlinear \\ distortion \\ \end{tabular} & \begin{tabular}{c} Complete RoF \\ system \\ system \\ \end{tabular} & \
\begin{tabular}{c} Suppression of second \\ and third order \\ nonlinearities \\ \end{tabular} &
\begin{tabular}{c} Wavelength dependent \\ transmission, i.e., suppression of \\ nonlinear components for \\ anti-phased wavelengths only. \\ \end{tabular} \\ \hline
4 & \begin{tabular}{c} [PERSON] \\ et al. [18] \\ \end{tabular} & Digital & \begin{tabular}{c} Digital \\ Prediction \\ (DPD) \\ \end{tabular} & \begin{tabular}{c} Third order \\ nonlinearities \\ \end{tabular} & \begin{tabular}{c} Power \\ Amplifier \\ \end{tabular} & \
\begin{tabular}{c} Wideband \\ linearization \\ achievable \\ \end{tabular} &
\begin{tabular}{c} DSP required is complicated. \\ Consumption of power is huge. \\ \end{tabular} \\ \hline
5 & \begin{tabular}{c} [PERSON] et al. [19] \\ \end{tabular} & Digital & DPD & ACPR, EVM & Laser & \
\begin{tabular}{c} Added accuracy with \\ less DSP requirements \\ \end{tabular} &
\begin{tabular}{c} High complexity and calculation \\ time for digital linearization for \\ higher nonlinearity order and \\ memory depth. \\ \end{tabular} \\ \hline
6 & \begin{tabular}{c} [PERSON] et al. [20] \\ \end{tabular} & Digital & DPD & ACPR & Laser/RoF & \
\begin{tabular}{c} Higher suppression in \\ ACPR by 15 dB \\ \end{tabular} &
\begin{tabular}{c} Feedback complexity. \\ High speed digitizer required. \\ Only applicable to uplinks. \\ Deployment of DPF at RRH side, \\ so prototype price passes to \\ customer side, adding \\ complexity to the RRH. \\ \end{tabular} \\ \hline
8 & \begin{tabular}{c} [PERSON] \\ et al. [22] \\ \end{tabular} & Digital & DPD & ACPR, EVM & Laser only & \
\begin{tabular}{c} Less complexity and \\ over head \\ \end{tabular} &
\begin{tabular}{c} High speed digitizer required. \\ Only applicable to uplinks. \\ Deployment of DPF at RRH side, \\ so prototype price passes to \\ customer side, adding \\ complexity to the RRH. \\ \end{tabular} \\ \hline
8 & \begin{tabular}{c} [PERSON] \\ et al. [22] \\ \end{tabular} & Digital & DPD & ACPR, EVM & Laser only & \
\begin{tabular}{c} Less complexity and \\ over head \\ \end{tabular} &
\begin{tabular}{c} ReF link was not composed of \\ laser-photodiode only. \\ Attenuators and amplifiers were \\ used so perhaps the signal \\ impairments were correlated due \\ to these components. \\ Limited to sinusoid 1/P signal. \\ \end{tabular} \\ \hline
9 & \begin{tabular}{c} [PERSON] et al. [23] \\ \end{tabular} & Digital & DPD & \begin{tabular}{c} C/HD2, HP2, \\ HP3 \\ \end{tabular} & \begin{tabular}{c} Combination of \\ fiber dispersion \\ and laser chirp \\ \end{tabular} & \
\begin{tabular}{c} Linearizes links up to \\ tens of km \\ \end{tabular} &
\begin{tabular}{c} Limited to sinusoidal \\ (single/dual) 1/P tones. \\ No ACPR, EVM shown. \\ \end{tabular} \\ \hline
10 & \begin{tabular}{c} [PERSON] et al. [24] \\ \end{tabular} & Digital & DPD & EVM & Laser & \
\begin{tabular}{c} Utilization of OFDM \\ signal with 5 MHz \\ bandwidth \\ \end{tabular} &
\begin{tabular}{c} Only magnitude (AM/AM) \\ Inear is not generic, contains \\ Lo dB attenuator. \\ \end{tabular} \\ \hline
11 & \begin{tabular}{c} [PERSON] \\ et al. [25] \\ \end{tabular} & Digital & DPD & ACPR, BER & Laser & \
\begin{tabular}{c} Utilization of OFDM \\ signal with 12.5 MHz \\ bandwidth \\ \end{tabular} &
\begin{tabular}{c} Joint compensation proposed for \\ PA and RoF hence reducing \\ improvement. \\ \end{tabular} \\ \hline
12 & \begin{tabular}{c} [PERSON] et al. [26] \\ \end{tabular} & Digital & DPD & EVM, ACPR & RoF system & \
\begin{tabular}{c} Utilization of LTE \\ 20 MHz signal \\ \end{tabular} &
\begin{tabular}{c} RoF link is not generic; contains \\ signal amplification by LNA and \\ a PA. \\ Unrealistic feedback for 10 km \\ length; requires an uplink for the \\ linearization of downlink. \\ \end{tabular} \\ \hline
13 & \begin{tabular}{c} [PERSON] et al. [27] \\ \end{tabular} & Digital & DPD & NMSE, ACPR & RoF system & \
\begin{tabular}{c} Replication of \\ 20 MHz with 16 QAM \\ modulation \\ \end{tabular} &
\begin{tabular}{c} FSD of O/P with and without \\ DPD is different after \\ normalization, DPD reduced the \\ bandwidth of the signal. \\ DFB laser has not been pushed to higher RF I/P powers to see the \\ efficacy of the predistorter. \\ \end{tabular} \\ \hline
14 & \begin{tabular}{c} [PERSON] et al. [28] \\ \end{tabular} & Digital & DPD & ACPR, EVM & RoF system & \
\begin{tabular}{c} Initialization \\ considering ideal and \\ no feedback \\ \end{tabular} &
\begin{tabular}{c} ReSULTS are attenuation \\ dependent, i.e., results similar to \\ ideal case can be obtained with \\ proper attenuation using \\ different optimization \\ algorithms. \\ \end{tabular} \\ \hline
15 & \begin{tabular}{c} [PERSON] \\ et al. [29] \\ \end{tabular} & Electrical & \begin{tabular}{c} Analog \\ Predistortion \\ \end{tabular} & IMD3 & Laser & \
\begin{tabular}{c} Maintenance of phase \\ for generated IMD3 \\ components \\ \end{tabular} &
\begin{tabular}{c} Large scale production difficult \\ as variant predistorter required \\ per RoF transmitter. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}