1. A method for transmitting a plurality of input streams from a first signal processing circuitry to a second signal processing circuitry, comprising: processing each of a plurality of input data streams to generate a plurality of parallel pairs of data streams including an in-phase stream (I) and a quadrature-phase stream (Q) for each of the plurality of input data streams; modulating each of the plurality of parallel pairs of data streams with a selected one of at least three mutually orthogonal functions and each of the plurality of parallel pairs at a different signal width, respectively, to generate a plurality of data signals, each associated with one of the plurality of parallel pairs of data streams; generating a plurality of composite data streams by overlaying at least one data signal of the plurality of data signals in a first data layer with the at least one data signal of the plurality of data signals in a second data layer; controlling intersymbol interference between the plurality of composite data streams.