In this paper 4-level pulse amplitude modulation (PAM-4) analog radio over ¯ber (A-RoF) transmission through wavelength division multiplexed passive optical network (WDM- PON)architecture for future broadband ¯fth-generation (5G/5G+) cellular mobile communica- tion networks is proposed. The goal of future cellular mobile communication infrastructures of the next decade is retaining at least one-third of global market share in Europe regarding future network equipment and support higher spectral e±ciency providing ubiquitous access to wider spectrum applications in order to reduce the network energy consumption.An alternative solution that o®ers a good trade-o® between performance and complexity is multi-level signaling formats such as PAM-M, where multiple digital bits are encoded into di®erent signal amplitude levels or symbols. It is a relatively easy and e®ective way to double the bitrate of data transmission link by the implementation of PAM-4 modulation technique instead of well-known non-return-to-zero on-o®-keying (NRZ-OOK). In this paper, we investigated the use of PAM-4 modulation format for A-RoF signals transmission through the passive optical network (PON), which is standard- ized to NGPON2. In our research, we show the possible A-RoF transmitter implementation into improved ¯ber-optical line terminals (OLT), enabling to generate PAM-4 modulated signal and perform mm-wave signal transmission over the WDM-PON optical distribution network.