The present invention relates to a communication method, system and
signal, and in particular to a method and system for communicating
information in a digital signal. It has particular application to
satellite or terrestrial packet-based multi-user radio communication
systems. A method for communicating information in a digital signal
comprising data symbols is disclosed, wherein the information is encoded
in a sequence characteristic of pilot symbols distributed amongst the
data symbols, such that a receiver is able to determine the sequence
characteristic and retrieve the transmitted information. The invention
allows information to be encoded into a sequence characteristic of pilot,
symbols, rather than relying on modulating such information onto the
pilot symbols themselves. This allows a significantly larger number of
pieces of information to be transmitted than hitherto possible, and the
technique is more resistant to large frequency errors than prior
techniques.