Novel FEXT Cancellation and Equalization for High Speed Ethernet Transmission

Abstract

In high-speed multi-pair wireline communication systems, such as 10 gigabit Ethernet over Copper (10GBASE-T), far-end crosstalk (FEXT) becomes a major impairment and needs to be suppressed to increase data rates. Conventional techniques based on crosstalk cancellation are not suitable for FEXT due to the fact that the disturbing source of FEXT is generally unknown to the victims. This paper presents two different approaches to efficiently deal with FEXT over unshielded twisted-pair (UTP) copper cables. To eliminate the error propagation problem in practice, both approaches use the Tomlinson-Harashima precoding (THP) technique which however makes the transceiver design nontrivial. In the first approach, FEXT is treated as noise and a new feedforward FEXT canceller is proposed. Compared with conventional techniques, the proposed FEXT canceller can mitigate the non-causal part of FEXT, thus leading to better FEXT cancellation performance. In the second approach, FEXT is treated as signal, and the general multi-input multi-output (MIMO) equalization technique is combined with the TH precoding technique to deal with both intersymbol interference (ISI) and FEXT. Different from the existing works, the proposed designs comply with the 10GBASE-T standard and they are suitable in real applications. Simulation results verify that the proposed approaches can achieve much better performance in terms of decision-point signal-to-noise ratio (DP-SNR) than conventional techniques. It is also shown that the hardware complexity of the transceiver can be reduced by about 37.2% by utilizing the increased DP-SNR in the proposed designs.