## 1 Introduction  
The fast evolution of Internet traffic and emerging applications can be considered a significant driver for high-capacity and cost-effective optical fibre transmission technologies. The technique of the information transmitting between two positions is a fibre optic communication, which is completed by sending light within the optical fibre [1]. This communication system can be used for long distance applications that's needed a total transmission capacity and increasing cost recovering. Optical transmission systems are popular for maintaining low power for short-to-medium-range wireless communications. However, for other applications where transmission distance is large, high power is required. In an optical fibre, various nonlinear effects begin to appear as the optical power level increases [2].  
Radio over fibre (RoF) is an analogue optical link transmitting modulated RF signals. It assists in transmitting the RF signal downlink and uplink to and from the central station (CS) to the base station (BS). The characteristics of great capacity, high speed with small losses are considered at the beginning for the RoF systems, where the main advantage of Rof systems is the mobile communication adaptability and flexibility to associate with the growth movement of the forthcoming 5G mobile communication in addition to the request services for gigabit size [3].  
The wavelength division multiplexing (WDM) technique is used in optical communication for the multiplexing sum of optical carrier signals that have various wavelengths within a single optical fibre. These signals have different laser light wavelengths to carry different signals. They can realize higher data rate, larger capacities, and enhanced flexibility with a comparatively low cost. This upgrade can be easily achieved for these systems, in addition to the bidirectional transmission advantage over a length of the single fibre at both transmitter and receiver [4].  
Using WDM as an alternative to the FDM (frequency-division multiplexing) technique was suggested in 1970 by [PERSON]. The characteristics of implementation any modulation scheme within WDM is realized for any wavelength; however, with the condition of the signal spectral, width must not exceed the limit of the using channel spacing. The total capacity per fibre optic within this WDM technique is assumed by N \(\times\) R, where R represents the channel bit rate and is supposed to be similar for all channels [5].  
The WDM bands have an approximation wavelength range value has not been standardized thus far. These bands, like O-band, S-band, and C-band, have a range different from another; for example, the range of 1260 nm to 1360 nm for O-band corresponds to a bandwidth of 14 THz, while the 1460 nm to 1625 nm range is for a grouping of S-band and C-band and corresponds to 15 THz of bandwidth [6]. The total available bandwidth per fibre optic in an individual O-band, S-band, and C-band is around 30 THz of the low-loss regions of a standard G.652 single-mode fibre [7].  
This paper focuses on the transmission of data streams over a range of optical fibre lengths using the WDM scheme. The channel spacing was maintained at 0.4 nm, and the input power was fixed, so that the WDM-RoF network execution can be analyzed.