Equalizer method and apparatus using constant modulus algorithm blind equalization and partial decoding
US6668014B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 9, 1999 |
| Grant date | Dec 23, 2003 |
| Priority date | — |
| Expiry date | Dec 9, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0046
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A digital communication receiver includes a blind equalizer using the Constant Modulus Algorithm (CMA) to compensate for channel transmission distortion in digital communication systems. Improved CMA performance is obtained by using a partial trellis decoder to predict 1 bit or 2 bits of the corresponding 3-bit transmitted symbol. The predicted bits from the partial trellis decoder are used to reduce the effective number of symbols in the source alphabet, which reduces steady state jitter of the CMA algorithm. Specifically, the received input signal to the CMA error calculation is shifted up or down by a computed delta (&Dgr;), in accordance with the predicted bit(s). In addition, a different constant gamma (&ggr;), for the CMA error calculation is selected in accordance with the predicted bit(s). The disclosed technique is applicable to trellis and non-trellis codes in which at least one bit of the present symbol can be predicted in advance and used to reduce the effective number of symbols in the source alphabet.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.