The present invention is directed toward a method and apparatus in a communications device for mapping a selected group of data bits into a predetermined number of two-dimensional symbols selected from a minimized alphabet of M two-dimensional symbols forming a symbol constellation, with one of the two-dimensional...http://www.google.com/patents/US5222077?utm_source=gb-gplus-sharePatent US5222077 - Radix mapping with variable number of symbols in mapping period
