METHOD FOR CONTROLLING ADAPTIVE MODULATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an adaptive modulation system controlling method by which transmission line quality is stably secured by solving the problems that the detection of line deterioration delays and that the transmission line quality is difficult to secure because the line is conventionally controlled on the basis of an error after the error occurs, estimating the line deterioration before an error takes place, further detecting quality recovery and selecting an appropriate modulation method. SOLUTION: This adaptive modulation system controlling method is to estimate a transmission line condition from the relation between an uncorrectable error occurrence condition due to error detection results and an error correction condition by the path metric value of Viterbi decoding, to select a modulation system in a transmitter and also to adjust a threshold at which a proper range to decide the error correction condition is specified.