Hierarchically modulated OFDM communication from a satellite-based transmitter with reduced secondary data loss from clipping
US7903629B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 30, 2009 |
| Grant date | Mar 8, 2011 |
| Priority date | — |
| Expiry date | Sep 10, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2647
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
High priority data and low priority digital data are transmitted as primary and secondary data in hierarchically modulated, orthogonal frequency division multiplexing (OFDM) from an earth-orbiting satellite. To enable the transmitter amplifier to be operated with less back-off from saturation without clipping, the low priority OFDM symbols have fewer samples than the high priority OFDM symbols, and the high priority samples on which the low priority samples are superimposed are selected according to a first deterministic rule using sample power comparisons of the high priority samples to concentrate the low priority samples on those high priority samples having lower (optimally, the lowest) sample power. The low priority samples are distributed on the selected high priority samples according to a second deterministic rule relating the original low priority sample order to the original high priority sample order.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.