Method and System for Corrupt Symbol Handling for Providing High Reliability Sequences

• US 20140140446A1
• Filed: 10/28/2013
• Published: 05/22/2014
• Est. Priority Date: 06/20/2012
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: MagnaCom, Ltd. (Broadcom, Inc.)
• Inventors: Eliaz, Amir
• Granted Patent: US 9,166,834 B2
• Time in Patent Office: Days
• US Class Current: 375/340
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 1/16 Circuits
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/206 for modulated signals
• CPC Class Codes: H04L 25/03197 methods of calculation involving metrics
• CPC Class Codes: H04L 25/0328 with interference cancellation circuitry adaptations for interference cancellation within a sequence estimator H04L25/03305; interference related aspects of direct sequence spread spectrum H04B1/7097; interference related aspects of frequency hopping spread spectrum H04B1/715; see also H04B1/10
• CPC Class Codes: H04L 25/03834 using pulse shaping
• CPC Class Codes: H04L 25/03949 equalizer selection or adaptation based on feedback multiple signaling inclusive of a precoding command for adapting the transmitter H04L1/0031; feedback for transmit diversity systems H04B7/0619; selection of codebook or precoding matrix for MIMO diversity systems H04B7/0456
• CPC Class Codes: H04L 27/3405 Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power
• CPC Class Codes: H04L 27/38 Demodulator circuits; Receiver circuits

Abstract

For corrupt symbol handling for providing high reliability sequences, an inter-symbol correlated (ISC) signal is received. During sequence estimation when demodulating the received ISC signal, partial response samples in the ISC may be processed utilizing an erasure mechanism. The partial response samples are spread (e.g. interleaved) over time during modulation by a modulator. A determination is made as to whether to utilize self erasure or external erasure to process the spread partial response samples. The determination may be based on whether or not events of low SNR for corresponding ones of the partial response samples are identified. The external erasure may be utilized for processing the corresponding ones of the partial response samples when the events of low SNR are identified and the self erasure is utilized when the events of low SNR are not identifiable. Erasure results maybe fed back to the modulator.

Claims

1-20. -20. (canceled)

21. A method, comprising:

in a receiver;

receiving a sample of a signal;

determining, prior to calculating any branch metric values for said sample, whether low-signal-to-noise ratio events for said sample of said signal are detectable for said sample;

in instances that low-signal-to-noise ratio events for said signal are detectable prior to calculating any branch metric values for said sample, configuring said receiver to use external erasure for demodulating said sample;

in instances that low-signal-to-noise ratio events for said signal are not detectable for said sample prior to calculating any branch metric values for said sample, configuring said receiver to use self erasure for demodulating said sample; and

demodulating said sample.

22. The method of claim 21, wherein, when said receiver is configured to use external erasure, said demodulating said sample comprises:

determining, prior to calculating any branch metric values for said sample, a signal-to-noise ratio of said sample;

in instances that said signal-to-noise ratio of said sample is above a threshold, calculating a branch metric value for said sample based on said sample;

in instances that said signal-to-noise ratio of said sample is below said threshold, setting said branch metric value for said sample to a predetermined value.

23. The method of claim 22, wherein said predetermined value is zero.

24. The method of claim 22, wherein, in said instances that said signal-to-noise ratio is below said threshold, said demodulating comprises determining whether to generate an indication of an error event based on signal-to-noise ratio of each of one or more other samples of said signal.

25. The method of claim 21, wherein, when said receiver is configured to use self erasure, said demodulating said sample comprises:

calculating a branch metric value for said sample based on said sample;

determining a signal-to-noise ratio for said sample based on said calculated branch metric value for said sample;

in instances that said signal-to-noise ratio of said sample is above a threshold, keeping said calculated branch metric value; and

in instances that said signal-to-noise ratio of said sample is below said threshold, discarding said branch metric value.

26. The method of claim 25, wherein said predetermined value is zero.

27. The method of claim 22, wherein, in said instances that said signal-to-noise ratio is below said threshold, said demodulating comprises determining whether to generate an indication of an error event based on signal-to-noise ratio of each of one or more other samples of said signal.

28. A system, comprising:

a receiver comprising an erasure circuit, wherein said receiver is operable to;

receive a plurality of samples of a signal;

demodulate a first one or more of said samples using said erasure circuit configured for external erasure; and

demodulate a second one or more of said samples using said erasure circuit configured for self erasure.

29. The system of claim 28, wherein, when said erasure circuit is configured for external erasure, demodulation of a particular sample by said receiver comprises:

determination of a signal-to-noise ratio of said particular sample prior to calculating any branch metric values for said particular sample;

in instances that said signal-to-noise ratio of said sample is above a threshold, calculation of a branch metric value for said particular sample based on said sample;

in instances that said signal-to-noise ratio of said sample is below said threshold, setting of said branch metric value for said particular sample to a predetermined value.

30. The system of claim 29, wherein, in said instances that said signal-to-noise ratio of said sample is below said threshold, said demodulation of said particular sample comprises a determination of whether to generate an indication of an error event based on a signal-to-noise ratio of each of one or more other samples of said signal.

31. The method of claim 28, wherein, when said erasure circuit is configured for external erasure, demodulation of a particular sample by said receiver comprises:

calculation of a branch metric value for said particular sample based on said particular sample;

determination of a signal-to-noise ratio for said particular sample based on said calculated branch metric value for said sample;

in instances that said signal-to-noise ratio is above a threshold, use of said calculated branch metric value for survivor selection; and

in instances that said signal-to-noise ratio is below said threshold, discarding of said branch metric value.

32. The system of claim 31, wherein, in said instances that said signal-to-noise ratio of said sample is below said threshold, said demodulation of said particular sample comprises a determination of whether to generate an indication of an error event based on signal-to-noise ratio of each of one or more other samples of said signal.

33. A system, comprising:

a receiver comprising erasure circuitry and sequence estimation circuitry, wherein

said receiver is operable to;

receive a sample of a signal;

determine, prior to any calculation of branch metric values for said sample by said sequence estimation circuitry, whether low-signal-to-noise ratio events for said sample of said signal are detectable for said sample;

in instances that low-signal-to-noise ratio events for said signal are detectable prior to calculation of any branch metric values for said sample, configure said erasure circuitry to use external erasure for demodulation of said sample;

in instances that low-signal-to-noise ratio events for said signal are not detectable for said sample prior to any calculation of branch metric values for said sample, configure said erasure circuitry to use self erasure for demodulation of said sample; and

demodulate said sample.

34. The system of claim 33, wherein, when said erasure circuitry is configured to use external erasure:

said receiver is operable to determine, prior to any calculation of branch metric values for said sample by said sequence estimation circuitry, a signal-to-noise ratio of said sample; and

said sequence estimation circuitry is operable to;

in instances that said signal-to-noise ratio of said sample is above a threshold, calculate a branch metric value for said sample based on said sample; and

in instances that said signal-to-noise ratio of said sample is below said threshold, set said branch metric value for said sample to a predetermined value.

35. The system of claim 34, wherein said predetermined value is zero.

36. The system of claim 34, wherein, in said instances that said signal-to-noise ratio of said sample is below said threshold, said receiver is operable to determine whether to generate an indication of an error event based on a signal-to-noise ratio of each of one or more other samples of said signal.

37. The system of claim 33, wherein, when said erasure circuitry is configured to use self erasure:

said sequence estimation circuitry is operable to;

calculate a branch metric value for said sample based on said sample;

determine a signal-to-noise ratio for said sample based on said calculated branch metric value for said sample;

in instances that said signal-to-noise ratio is above a threshold, use said calculated branch metric value for survivor selection; and

in instances that said signal-to-noise ratio is below said threshold, set a branch metric for said sample to a predetermined value for survivor selection.

38. The system of claim 37, wherein said predetermined value is zero.

39. The system of claim 37, wherein, in said instances that said signal-to-noise ratio is below said threshold, said receiver is operable to determine whether to generate an indication of an error event based on signal-to-noise ratio of each of one or more other samples of said signal.

40. The system of claim 33, wherein said receiver comprises an equalization circuit and said determination of whether low-signal-to-noise ratio events for said sample of said signal are detectable for said sample is based on whether said equalizer can detect low-signal-to-noise ratio events for said sample.