A method of encoding video data comprising: generating coefficients based on digital sample values of the video data; determining a spectral efficiency for a channel; determining a value n based on the spectral efficiency of the channel; generating coefficient vectors, wherein each of the coefficient vectors includes n of the coefficients; determining an amplitude value for a coefficient vector based on a mapping pattern, wherein for each respective allowed coefficient vector in a plurality of allowed coefficient vectors: the mapping pattern maps the respective allowed coefficient vector to a respective amplitude value in a plurality of amplitude values, and the respective amplitude value is adjacent in an n-dimensional space to at least one other amplitude value in the plurality of amplitude values that is adjacent to the respective amplitude value in a monotonic number line of the amplitude values, and modulating an analog signal based on the amplitude values.