ADAPTIVE MODULATION/CODING COMMUNICATION SYSTEM

The invention proposes a communication system comprising- a transmitter and one or more receivers, said transmitter arranged to transmit over a communication link a sequence of physical layer frames at a physical layer symbol rate,- adaptive coding and modulation optimization means arranged to determine per receiver of said one or more receivers a first modulation and coding for transmitting data,whereby the transmitter maps the data in frames using an operational modulation and coding based on the first modulation and coding and inserts encoded and modulated data frames into said sequence. The transmitter can further insert into the sequence at least one fill frame modulated (and encoded) with a first fill modulation (and coding), said first fill modulation (and coding) selected from a set of fill modulations (and codings) comprising at least one fill modulation (and coding) with a modulation order higher than QPSK.The communication system further comprises link quality detection means to determine a metric of the communication link quality from a version of at least some of the physical layer frames received at the receive side and to convey the communication link quality metric to the adaptive coding and modulation optimization means.