This work reports the development of a high-gain and wideband photonic-assisted amplified radio over fibre (RoF) system based on the non-linear effect four-wave mixing (FWM). The microwave gain is defined as the difference between the electrical power photodetected using a FWM product and that from the conventional RoF system at the same optical power level. Numerical simulations and experimental results prove that microwave gain strongly depends on the system parameters, such as wavelength separation between pump sources, state of polarisation, radio frequency modulation frequency and DC bias voltage of optical modulator. Microwave amplification from 4 to 19 GHz, electrical signal-to-noise ratio higher than 51 dB and gain up to 26 dB at 17 GHz are demonstrated. Moreover, an optical-wireless network based on the photonic-assisted microwave application is proposed, with the purpose of illustrating its applicability.