A 1 Gb/s optical link is to be operated at the 1.55 ?m wavelength. Suppose the dispersion at the 1.55 ?m wavelength is 17 ps/km-nm, and the attenuation is 0:2 dB/km. For achieving a desired error probability, we are given that the receiver requires at least -30 dBm of power, and the maximum pulse spread must be no more than half of the bit period. The transmitted pulse has a spectral width of 0.5 nm, and the transmitter outputs a power of 1 mW. What are the link length limits due to power and dispersion?