Next-generation access networks (NGANs) mainly include wavelength division multiplexing (WDM) based 60GHz Radio over Fibre systems (60G-RoF) and WDM Passive Optical Networks (WDM-PONs). Semiconductor optical amplifier may be the key device of colorless unit in these WDM based systems. The device can be effectively utilized as external modulator because it can perform simultaneously amplification and modulation. However the main limitation is the modulation speed of the system. The lecture will overview the new generation optical access networks, it will focus Reflective SOA based solutions. The system performance and main limitations will be presented.