Radio communication system
US6781951B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 22, 1999 |
| Grant date | Aug 24, 2004 |
| Priority date | — |
| Expiry date | Oct 22, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L1/18
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A method of operating a radio communication system uses orthogonal signals for transmission of packets of data between two or more stations. In the transmitter data is encoded onto a plurality of orthogonal carriers by a differential phase modulation technique, for example DQPSK. The carriers are combined into a single signal by an inverse discrete Fourier transform and clipped at a predetermined amplitude before being transmitted to reduce the crest factor of the transmitted signal. The phase of one or more of the carriers is randomized before each data packet, hence a different crest factor will result for retransmissions of the same packet. This ensures that if a packet is difficult to transmit, because of reduced signal to noise ratio caused by clipping, it will retransmit successfully.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.