MIMO Equalization for High-Speed Communication Under Channel Variability
12 March 2018
High-speed communication over mutually coupled channels can be severely affected by intersymbol interference (ISI) and crosstalk (XT). Multiple-input multiple-output (MIMO) equalization is known to mitigate both ISI and XT, but requires accurate channel information at the receiver (RX) and/or transmitter (TX) when the channel is stochastic. However, since adjusting the equalization filters to the specific channel realization implies a considerable implementational and computational complexity, it might be preferable to keep (some of) the equalization filters fixed irrespective of the specific channel realization, especially when the channel variability is relatively small. Therefore, we propose a general MIMO transceiver scheme where (some of) the equalization filters depend on the channel statistics rather than the actual channel. More specifically, by considering fixed linear MIMO pre-equalization combined with adjustable MIMO decision feedback equalization (DFE), the complexity associated with passing channel information from the RX to the TX is avoided, and the computationally intensive, iterative calculations of the fixed pre-equalizer can be performed offline, rather than on-chip. The proposed equalization scheme is shown to yield only a small performance degradation compared to fully adjustable equalization schemes, thereby enabling multi-Gbit/s chip-to-chip communication over low-cost electrical interconnects which are prone to manufacturing tolerances.
