Transmitter, receiver, multi-class multimedia broadcast/multicast service system and modulation method thereof

摘要

A multi-class multimedia broadcast/ multicast service (MBMS) system includes a transmitter and at least one receiver. The transmitter transmits N primary signals by N primary channels and an auxiliary signal by an auxiliary channel, wherein a resolution of the auxiliary signal is identical to a resolution of the primary signal with the highest resolution and the constellation mappings of the auxiliary signal and the primary signal with the highest resolution on the corresponding modulation constellations can be coupled. The receiver couples the primary signal with the corresponding auxiliary/virtual auxiliary signal to obtain a lower-resolution virtual auxiliary signal, which can also be coupled with the primary signal having the same resolution. Therefore, receiving quality of each resolution is improved by combining the primary signal and the corresponding auxiliary/virtual auxiliary signal.