Phase noise and additive noise estimation in a QAM demodulator
US6249180A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 17, 2000 |
| Grant date | Jun 19, 2001 |
| Priority date | — |
| Expiry date | Apr 17, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0081
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A QAM demodulator having a carrier recovery circuit that includes a phase estimation circuit and an additive noise estimation circuit which produces an estimation of the residual phase noise and additive noise viewed by the QAM demodulator. The phase noise estimation is based on the least mean square error between the QAM symbol decided by a symbol decision circuit and the received QAM symbol. The additive noise estimation is based on the same error as in the phase noise estimation, except that it is based only on QAM symbols having the minimum amplitude on the I and Q coordinates. The additive noise estimation is not dependent on the phase of the signal, thus, is independent of the phase noise estimator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.