MULTIPLEX LEVEL CODING METHOD AND MULTIPLEX LEVEL DECODING METHOD IN COMMUNICATION SYSTEM, AND MULTIPLEX LEVEL CODER IN THE COMMUNICATION SYSTEM, AND DEVICE STORING SOFTWARE OF MULTIPLEX LEVEL CODING METHOD IN THE COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a communication system where optimum performance can be realized in an application of a DAB(digital audio broadcast) system adopting the IBOC-AM(in-band on-channel amplitude modulation) system and other communication system with a limited bandwidth. SOLUTION: A series of information bits are divided into parts of bits and they relate to levels different from each other in terms of multiplex level coding. At least one code is applied to an information bit of each level in a designated subset among all level sets, the information bit with respect to the level in the designated subset is coded and information bits with respect to levels in subsets that are not designated are not coded. In order to select a transmission modulation symbol in the communication system, both the information bits that are coded and the information bits that are not coded are utilized. This invention attains a configuration where the coding gain is enhanced from that of a conventional technology and an inequality error can be protected similarly to the case with that of time diversity in the transmission through a channel.