Method and apparatus for efficient carrier bin search for a composite spreading code
US7436878B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 24, 2005 |
| Grant date | Oct 14, 2008 |
| Priority date | — |
| Expiry date | Mar 31, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0065
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A matched filter decorrelator is described for efficiently performing a carrier frequency search while despreading a P/N long code constructed from two or more constituent codes such as codes A, B, C. The received signal is phase rotated into a frequency bin and partially despread, preferably over all but one of the constituent codes. To despread the final constituent code, the partially despread signal is input in parallel into frequency bins, where a phase rotator sets each input to a different bin. The frequency bins are then despread in parallel over the final constituent code, and an energy peak in one accumulator indicates which bin is the carrier frequency. Alternatively, a Fourier transform could be used over each of the frequency bins. By partially despreading prior to division into carrier frequency bins, hardware and computational burden are reduced as compared to prior art decorrelators. The present invention is particularly apt for use with an acquisition burst in a secure network.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.