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results in the generation of side bands which are amplified to produce highly stable carriers.A 2 31 -1 length pseudorandom binary sequence (PRBS) forms the baseband data. The electrical mixer is used to upconvert the 2.5 Gb/s baseband signal with the 25 GHz RF signal. This produces a DWDM. The optical spectrum at the output of intensity modulator is shown in Figure 5. Single-drive MZM has only one single-driving voltage applied to either arm of MZM. For instance, it is assumed that there is no voltage driving onto arm 1 while a specific voltage applied on arm 2. The transmitted optical field E o (t) at the output of a single-drive MZM is a function of this specific voltage and a bias DC voltage, V bias . The MZM is biased at 0:5vp to generate the required DSB signals. There is an existence of the phase modulation of the optical carrier, that is, the chirping effect. Thus, by using a single-drive MZM, generated optical signals are theoretically not chirp free. This occurs particularly in the case of using a zcut LiNbO 3 MZM, which has an asymmetrical structure of field distributions. In practice, a small amount of chirp might be useful for transmission.The base station has a 12.5/25 GHz optical interleaver with two outputs. This interleaver has the central frequency of 191.15 THz, a frequency spacing of 25 GHz, and a bandwidth of 13 GHz. It has an insert loss of 2 dB. The no polarization sensitivity is unmarked during the simulation. The interleaver set apart the odd and even sidebands, so that they can be used for uplink and downlink connections. The odd and even sidebands are shown in Figures 6 and 7, respectively. TOF 1 output gives the spectrum for downlink receiver which is shown in Figure 8. The 3R generator and eye diagram analyzer are used to find the eye diagram of the downlink receiver. TOF2 is used to tune the required carrier at 194.43 THz. The TOF2 output is shown in Figure 9. The carrier is modulated via a LiNbO 3 -MZM driven by the required uplink data. PRBS data of 2 31 2 1 word length is used here. The optical spectrum which is affected by losses is amplified by an erbium-doped fiber amplifier and transmitted over another 20 km SMF-28. The uplink part is also analyzed by using 3R generator and eye diagram analyzer. Figures 10 and 11 show the eye diagram of uplink and downlink, respectively. We get an open-eye diagram which shows that reliable communication is possible. CONCLUSION

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