The invention, in part, provides a method of (and corresponding apparatus for) receiving (and similarly transmitting) data signals over data lines. Such a method of receiving comprises: organizing said data lines into groups, each group having N input data signals and M reference signals, wherein N is a non-zero, positive integer; associating M reference signals on M reference lines with each group of N input data lines, wherein M is a non-zero, positive integer and N>M; and receiving data on said data lines and reference signals on said reference lines; and determining, for each group, data values on said data lines according to differences between signal parameters on said N data lines and signal parameters on said M reference lines, respectively.