Optical fiber research indicates that dispersion compensation along a 40-Gb/s terrestrial link can result from either periodic compensation at amplifier locations -- especially if prechirp is added at the beginning -- or from compensation functions located at the end of the link. Noting that these methods have never been directly compared, researchers at Italy's University of Padova, Pirelli Labs and Fondazione Ugo Bordoni described a numerical study of each method in the October issue of IEEE Photonics Technology Letters. The article also included experimental results obtained on a 4 x 40-Gb/s system. The researchers concluded that G.652 optical fibers transmit 40 Gb/s well with highly dispersed pulses and dispersion compensation located entirely at the end. Periodic compensation, however, applies better to G.655 fiber systems.