Etude de Modulations a Bande Reduite pour Liaisons Hertziennes a Grande Efficacite Spectrale (Study of Narrow Band Modulation for Radio Links with High Spectral Efficiency)

摘要

The performance of high bit-rate data transmission systems (140 Mbit/sec with 30 MHz between channels) is studied. The narrow band adaptation of the 16 level quadrature amplitude modulation (16QAM) is compared to the 64QAM. Methods to improve the spectral efficiency for 30 and 20 MHz separation are discussed. It is shown that the results of the narrow band 16QAM are equal to or better than the 64QAM regarding either noise to signal performance or multipath and systems imperfection problems. The same conclusion applies to narrow band 64QAM when compared to 256QAM for 20 MHz channel separation.