JOINT SIGNALING STRATEGIES FOR APPROACHING THE CAPACITY OF TWISTED-PAIR CHANNELS

A technique is presented for jointly optimizing the signaling in the t wo directions of transmission on a twisted-pair communications channel . It is then applied to twisted-pair channel models with monotonic cha nnel response and crosstalk transfer functions, While the signaling st rategy presented in this paper can achieve only a lower bound on the t rue channel capacity, it is a significant improvement over existing si gnaling schemes, In particular, in contrast with existing schemes, the maximum information rate for the joint signaling strategy increases w ithout bound as the signal-to-noise ratio (SNR) approaches infinity. I t is also shown through numerical results that the proposed signaling strategy generalizes naturally to more practical nonmonotonic twisted- pair channel models incorporating bridge taps and other nonidealities, Finally, the form of the optimal signaling strategy suggests a relati vely straightforward implementation using multicarrier modulation.