Green and fast DSL via joint processing of multiple lines and time-frequency packed modulation

In this paper, strategies to enhance the performance, in terms of available data-rate per user, energy efficiency, and spectral efficiency, of current DSL lines are proposed. In particular, a system wherein a group of copper wires is jointly processed at both ends of the communication link is considered. For such a scenario, (a) the statistical multiplexing gain for the generic end user is analyzed; (b) a resource allocation scheme aimed at energy efficiency maximization is proposed; and, finally, (c) time-frequency packed modulation schemes are investigated for increased spectral efficiency. Results show that a joint processing of even a limited number of wires at both ends of the communication links brings remarkable performance improvements with respect to the case of individual point-to-point DSL connections; moreover, the considered solution does represent a viable means to increase, in the short term, the data-rate of the wired access network, without an intensive (and expensive) deployment of optical links.