Patent ID: 8160175

Claim:
A method for transmitting signals in a communication system, comprising the steps of determining a first modulation scheme; determining at least one position for the transmission of quasi-pilot symbols in a data transmission stream; determining at least one further modulation scheme, having a smaller number of amplitude or phase ambiguities than the first modulation scheme, for modulation of data in the quasi-pilot symbols; transmitting data in the communication system according to the at least one further modulation scheme at the determined position for the quasi-pilot symbols; transmitting data in the communication system according to the first modulation scheme at other symbol positions within the data transmission stream; wherein the at least one further modulation scheme has a lower number of modulation states than the first modulation scheme, the method further comprising the steps of: selecting a modulation scheme having more modulation states than the first modulation scheme; transmitting a quasi-pilot symbol using the modulation scheme that has the lower number of modulation states than the first modulation scheme, thereby replacing an original data symbol; and transmitting bits from the original data symbol replaced by the quasi-pilot symbol together with bits of another data symbol, using said selected modulation scheme having more modulation states than the first modulation scheme.