| 摘要 |
Degree of hierarchical modulation can be varied as a function of satellite position, where such hierarchical modulation can be a combination of phase and amplitude shifts. As each satellite in a multiple satellite system moves towards a D-node or an A-node position, the offset angle of a phase-based hierarchical modulation scheme can be varied. Starting with the lowest satellite position in the sky an offset angle for overlay bits can progressively increase as the position of the satellite in the sky increases. At a satellite's highest point in the sky, the overlay offset angle can be at its maximum. The value of a varying overlay offset angle (for each satellite) can be embedded in an Overlay Identification Marker (OIM) in the broadcast. The receiver can then appropriately correct MRC weightings (weighting more heavily the (higher lying) satellite). |
