METHOD TO MINIMIZE COMPATIBILITY ERROR IN HIERARCHICAL MODULATION

摘要

The present invention involves a method and system for transmitting two levels of data in a hierarchical transmission schema. A first modulated signal is generated based on first input (302). A second modulation signal is generated based on a second input (304) that has a data rate that is a fraction of the data rate of the first modulated signal. The second modulation signal has known instances where the second modulation signal has no energy. In a system (300) where the first modulation is quadrature phase shift keying (QPSK), the second modulation signal can be a secondary phase offset. A receiver (340) in the system that has a priori knowledge about the timing relationship between the first data signal and the instances when the second data signal is present will be able to detect both data signals optimally.