Method and system for data communication, using M-ary modulation scheme and inleaving means

A method of, and system for, communicating s-bit symbols using an M-ary modulation scheme in which a plurality of code words are arranged as rows of a block which is read-out orthogonally to the rows. In order to increase the dependability of the recovered code words, when the code words are stored or read-out the order of the bits forming some of the s-bit symbols is transformed so that those which would have been least significant bits (LSBs) are most significant bits (MSBs) and vice versa, the MSBs being affected less by noise than the LSBs when transmitted. At the receiver those s-bit symbols which have been transformed are restored to their original order.