Maximizing power and spectral efficiencies for layered and conventional modulations

Methods and apparatus for maximizing power and spectral efficiencies are described in a wireless communication system. The invention is particularly useful for layered modulation applications since power levels for such applications are relatively high. A layered modulation signal comprises an upper and lower layer signal interfering with each other within the same frequency band so that the upper layer signal can be demodulated directly from the layered modulation signal, and the lower layer signal can be demodulated after subtracting the first layer signal from the layered signal. The invention uses one or more of the following four signal planes in a communication signal, including varying the symbol rate (rather than the coding rate), reducing or eliminating the protection band, reducing excess signal bandwidth, and applying layered modulation within the old or inherited signal protection band.