Soft decision output generator
US6731700B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 4, 2001 |
| Grant date | May 4, 2004 |
| Priority date | — |
| Expiry date | May 18, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L1/0054
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
An apparatus for and method of generating soft decision information from a sequence of hard symbol decisions output from a decoder in a concatenated communications receiver. Soft symbol decisions are computed given hard symbol decisions from the equalizer, channel estimation information (i.e. FIR filter taps used to estimate the channel), and the input samples received from the channel. The log likelihood ratio (LLR) for all symbol possibilities is calculated by computing the conditional probability of the input sample sequence given the hard symbol decision sequence. The noise variance is optionally used in computing the soft output values, thus improving the overall performance of the receiver. In one embodiment, symbol vectors are calculated beforehand and stored in a table. An error vector calculator functions to calculate an error vector that is applied to soft output calculation units. Each soft output calculation unit functions to generate a soft output value for a particular symbol candidate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.