**7. Conclusion**

Basically, RoF is a transmission system of analog signal since it distributes a radio waveform from CS to BS direct at radio carrier frequency. A lot of way can be studied and developed to increase the performance of the RoF. This is why RoF is an ideal technology for the future gen‐ eration. RoF also provides low attenuation and broad bandwidth. It is also immune to elec‐ tromagnetic interference (EMI), which is a radio‐frequency interference where disturbance generated by an external sources that affects an electric circuit by electromagnetic induction, coupling or conduction.

RoF system employing WDM technique is simulated using Optisystem 12.0. WDM is among the best method to be used in RoF. WDM enables transmission of multiple signals through a single fiber over large and can exploit the fiber network bandwidth. Various transmission formats can be supported by various optical channels. Plus, WDM enables the capacity of an optical fiber increase compared to simple point to point link that only enable to carry only single wavelength.

EDFA amplifier is used in this system because it has a lot of advantages. EDFA amplifier pro‐ vides low noise figure. It also has an independent polarization. Thirdly, the dynamic range is large. The power transfer efficiency of EDFA amplifier is quite large. It also has relatively flat gain. Thus, it is very suitable for long‐distance communication.

RoF is a technology that really cost‐effective because in this technology, all of the expensive components can be shared by several BS. The installation and maintenance of RoF are easy since the concept of centralized configuration enables all sensitive components being located in safer surrounding. To modulate an optical sources, an electrical signal is used, and the modulated signal will be carried out through optical fiber to the receiver side. When the signal is directly modulated to the optical fiber, power consumption could be decreased, while the frequency of radio carriers is very high at the antenna side. Power consumption also can be decreased by having a simple radio station. All complex equipment and devices are kept at the CS.

RoF also provides operational benefits in terms of operational flexibility. Intensity modu‐ lation direct detection (IMDD) technique could be made in order to operate as a linear system. Low dispersion fiber (SMF) with combination with modulated RoF sub carriers (SCM) could be used to achieve linear system. The same radio over fiber network can be used to distribute multi‐operator and multi‐service traffic which results in huge economic savings.
