Frequency offset estimation using the phase rotation of channel estimates
US5422917A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 4, 1993 |
| Grant date | Jun 6, 1995 |
| Priority date | — |
| Expiry date | Jan 4, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0065
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A receiver (10) for extracting complex values by reference to a local frequency reference determines the frequency offset between a local oscillator (16) and the carrier by employing a circuit (40) for determining a "phase rotation." When a record of the input signal is determined to have resulted from a predetermined reference sequence of complex values, the phase-rotation circuit (40) compares the phases of complex values extracted from this record with corresponding symbols of the reference sequence. By comparing this difference for one part of the sequence with that for another, circuitry (38, 50, 52, 53, 54) in the receiver infers the frequency offset between the transmitter reference and the receiver reference, and a complex multiplier (34) compensates for this offset by multiplying the successive complex-valued samples by a complex exponential whose frequency is the negative of the frequency offset.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.