Method and apparatus for despreading OQPSK spread signals
US6363106B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 16, 1998 |
| Grant date | Mar 26, 2002 |
| Priority date | — |
| Expiry date | Mar 16, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2331
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Incoming signals in a receiver for Direct Sequence Code Division Multiple Access systems are despread using Offset-QPSK spreading as the transmitting spreading format combined with arbitrary data modulation formats, such as BPSK and QPSK. The receiver has a pseudonoise (PN) generator for generating a unique PN sequence signal. The PN sequence signal is divided into a real and an imaginary component. The complex input signal is divided into inphase and quadrature components. The inphase and the quadrature components of the input signal are downsampled to provide either two complex samples per chip period or one complex sample per chip period. In the latter case, the downsampling instants are delayed by a quarter of a chip period. Each downsampled complex signal is correlated with the corresponding segment of the complex PN sequence signal of the receiver. In the case where two samples per chip are provided after downsampling, the correlation values obtained for odd and even complex samples of the downsampled input signal are summed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.