Faster vs. Denser: Networks Reach Another Crossroad

Daniel C. McCarthy, Senior Editor

Pretty much any engineer with bills to pay will design and develop systems from a simple principle: Maximize performance while minimizing costs. Different disciplines measure success by different metrics. In telecommunications networks, success is measured by spectral efficiency, the number of bits that can be sent down a single fiber in a given time.

Today fibers in a state-of-the-art network pack in 160 channels, each transmitting 10 Gb/s. That works out to a spectral efficiency of 0.2 bits/s/Hz. Any technology that can double efficiency to 0.4 bits/s/Hz, without a proportionate increase in capital or operational costs, translates into savings for the carrier…