MULTIPLEX LEVEL CODING OF FRACTION BIT

摘要

PROBLEM TO BE SOLVED: To attain efficient coding for a symbol with a multiple coding that is hardly susceptible to errors. SOLUTION: The method and system are to code a symbol effectively with multiple level coding and a symbol element susceptible to errors is much more strongly coded over elements hardly susceptible to errors. The constellation of non binary symbols is processed by a fraction bit transfer speed converter connecting to an encoder of a multiple level to generate the constellation of efficient and effective symbols. Concretely digital data are coded and mapped onto a set of symbols while two least significant bits are coded in a multiple level code. A fact that an error in the least significant bit is easily caused is recognized and the least significant bit is coded by using a stronger code than a code for a succeeding bit to the least significant bit. The most significant bit is mapped with an aid of a fraction bit transfer speed mapping device 51 that optimize a selected aspect of the constellation of symbols such as a mean power.