US 7,313,750 B1Granted

Efficient soft decision demapper to minimize viterbi decoder complexity

AssigneeRalink Technology Corporation

InventorsShuling Feng, Chien-Cheng Tung

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Abstract

A receiver system that receives signals and has a demapper device that is responsive to an equalizer output and generates a demapper output including one or more bit metrics. The receiver system also generates equalizer output, and the demapper uses distance measure to calculate bit metrics. The receiver system uses demapper output to generate a processed output. The receiver system further includes a convolutional decoder which is responsive to the processed output, and subsequently generates a decoded bit sequence, as well as uses the processed output to generate one or more path metrics. The convolutional decoder uses bit metrics and path metrics to the decode processed output, to generate a decoded bit sequence. The receiver system uses the distance measure to reduce the size of the bit metrics and the size of the path metrics to improve the performance of said convolutional decoder.

A receiver system for receiving signals comprising:

a demapper device being responsive to an equalizer output for processing the equalizer output to generate a demapper output, said demapper output for including one or more bit metrics, said receiver system being responsive to a received signal for processing the received signal to generate said equalizer output, said demapper device for using a distance measure to calculate said bit metrics, said receiver system for using said demapper output to generate a processed output;
and
a convolutional decoder being responsive to said processed output for processing the processed output to generate a decoded bit sequence, said convolutional decoder for using said processed output to generate one or more path metrics, said convolutional decoder for using said bit metrics and said path metrics to generate said decoded bit sequence, said receiver system for using said distance measure to reduce the size of said bit metrics and the size of said path metrics to improve the performance of said convolutional decoder;
wherein said received signal being modulated using a modulation scheme, said received signal for including a bit sequence comprising an in-phase bit bI,k and a quadrature bit bQ,k, said modulation scheme for including a constellation for being partitioned into two sets of in-phase symbols SI,k(0) and SI,k(1), said constellation for being partitioned into two sets of quadrature symbols SQ,k(0) and SQ,k(1);
and
wherein said distance measure is a simplified Manhattan distance having an in-phase part dI,kc and a quadrature part dQ,kc, said equalizer output for including an ith subcarrier, each of said bit metrics for including an in-phase bit metric m(bI,k)c and a quadrature bit metric m(bQ,k)c, said demapper device for using a channel frequency response H(i) for said ith subcarrier and a minimum function (min) to calculate said in-phase bit metric according to
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65 more elements

Facts

Application

10/912,996Filed 5 Aug 2004 · us provisional application

Priority

6 Aug 2003

Granted

25 Dec 2007

Term ends

Not estimatedThe source records don’t support an estimate.

Classification14 codes

H03M 13/41
Sequence estimation, i.e. using statistical methods for the reconstruction of the original codes: using the Viterbi algorithm or Viterbi processors
H03M 13/6325
Joint error correction and other techniques: error control coding in combination with demodulation
H03M 13/6527
Intended application, e.g. transmission or communication standard: ieee 802.11 [wlan]
H04L 1/0054
Arrangements at the receiver end: maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms

Abstract

Claims18