Information transmission system
US5636247A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 21, 1995 |
| Grant date | Jun 3, 1997 |
| Priority date | — |
| Expiry date | Mar 21, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/26035
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A system for transmitting information over an OFDM channel using phase shift keying encoding employs a bit mapping encoder to reduce the crest factor (ratio of peak voltage to RMS voltage). For a 16 subchannel OFDM system using QPSK encoding, a first set of four symmetrically positioned pairs of subchannels is used to encode two bits of information on each subchannel. A second set of four symmetrically positioned pairs of subchannels is used to encode only one bit of information on each subchannel, with the resultant phasor for each pair of the second set of pairs of subchannels being orthogonal to the resultant phasor for one of the pairs of the first set of subchannels. With this arrangement, the crest factor is reduced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.