Dispersion and attenuation problems are the most important factors that limit dense wavelength division multiplexing (DWDM) system performance. Dispersion causes pulse broadening of the optical spectrum, and the attenuation degrades the optical signal. In this paper, dispersion compensation fiber (DCF) and cascaded repeaters techniques have been proposed to reduce linear and nonlinear problems by using two different modulation formats (carrier-suppressed return zero [CSRZ] and optical modulator) and two various channel spacings (100 and 50 GHz). The cascaded repeater offers the best performance at 100 GHz channel spacing with 37 quality factors for CSRZ and optical modulation schemes; however, the DCF network design is more compatible with the CSRZ modulation format with 27 quality factors. For 50 GHz channel spacing, the cascaded repeater offers the best performance with 31 quality factors for CSRZ and optical modulator techniques; the DCF technique comes in next with 27 quality factors for CSRZ and 19 for optical modulators.