Frequency offset tracking
US7668252B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 31, 2005 |
| Grant date | Feb 23, 2010 |
| Priority date | — |
| Expiry date | Jul 28, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0075
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
The present invention relates to estimating and correcting for frequency offset errors in wireless receivers, and is particularly but not exclusively related to MIMO WLAN applications. The present invention provides an improved method of tracking receiver frequency offsets in a receiver for MIMO systems. These receiver based frequency offset components are caused by errors or inaccuracies in various receiver sub-systems such as phase lock loops or carrier frequency oscillator error, and sampling clock rate errors. The frequency offsets due to each of a number of receiver sub-systems are estimated by monitoring frequency offsets on a number of channels or subcarriers (such as OFDM pilot channels) on different frequencies. These channel frequency offsets are preferably estimated by detecting the phase rotation between adjacent pilot symbols on each respective channel. They are then weighted according to a quality parameter of the estimates, which corresponds to their accuracy. An example of a quality parameter is the effective SNR of the respective channels, or preferably the error variance of the phase rotation. In an embodiment the quality parameter is or is proportional to ∥Hx∥2. …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.