Successive interference canceling for CMDA
US7190710B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 12, 2002 |
| Grant date | Mar 13, 2007 |
| Priority date | — |
| Expiry date | Jul 1, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B2201/709709
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Successive interference canceling for CMDA. ICI may result from a signal's multipath effects, or by filtering/suppression of some of the component energy of the signaling waveforms. Energy component attenuation destroys orthogonality of CDMA symbols thereby causing ICI. An ICF suppresses frequency domain portions (attenuates ingress), but also introduces ICI. Following the ICF, the signal is de-spread, sliced, re-spread and convolved with the ICF echoes (except first tap echoes). Convolving re-spread hard decisions with delayed ICF taps is equivalent to partially re-modulating the first-pass hard decisions to efficiently “add-back-in” the signal energy which was blanked/subtracted by the ICF. Alternatively, parameter estimation de-rotates and re-rotates soft symbols and hard decisions, respectively, compensating for undesirable symbol rotation. The convolved signal is subtracted from a delayed version of the ICF output signal. If desired, this process may be repeated successively to enhance the accuracy of the obtained data decisions in the next stage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.