Soft decision decoding with channel equalization

• US 5,271,042 A
• Filed: 10/13/1989
• Issued: 12/14/1993
• Est. Priority Date: 10/13/1989
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Borth, David F., Labedz, Gerald P., Rasky, Phillip D.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): TSE, YOUNG TOI
• Application Number:
  US07/422,177
• Time in Patent Office: 1,523 Days
• Field of Search: 375/18, 375/58, 375/96, 375/99, 375/101, 375/103, 375/102, 371/43, 364/724.11, 455/296, 455/312, 455/303, 455/305
• US Class Current: 375/348
• CPC Class Codes: H04L 25/03318 Provision of soft decisions

Abstract

In a communications network having time-dispersed signals, there is provided a mechanism for soft decision decoding. It comprises: radio reception of a time-dispersed signal, at least partly equalizing those time-dispersal effects, recovering information contained in the signal, multiplying with that recovered information the absolute value of that at-least-partly-equalized signal (scaled by a number derived from channel conditions over a time during which at least part of the information to be recovered is distributed), and error-correcting the multiplied information by a Viterbi algorithm channel decoding scheme of error correction. Accordingly, soft decision information is generated from within the equalization process itself.

Claims

1. A method of soft decision decoding comprising the steps of:

receiving a time-dispersed signal,

recovering information, having a time-dispersal effect, contained in the time-dispersed signal,

accounting for the time-dispersal effect of the recovered information,

weighting the recovered information using a weight comprising an absolute value of the received time-dispersed signal,

and evaluating the recovered information considering the weight given thereto.

2. A method as claimed in claim 1 above, wherein accounting for those time-dispersal effects and recovering information comprises equalization.

3. A method as claimed in claim 1 above, wherein the step of accounting for the time-dispersal effects comprises the step of equalizing a plurality of multipath time-dispersal effects.

4. A method as claimed in claim 1 above, wherein accounting for those time-dispersal effects and recovering information comprises adaptive equalization with channel matched filtering and sequence estimation.

5. A method as claimed in claim 1 above, wherein accounting for those time-dispersal effects and recovering information comprises adaptive equalization with channel matched filtering and maximum likelihood sequence estimation.

6. A method as claimed in claim 1 above, wherein accounting for those time-dispersal effects and recovering information comprises decision feedback equalization.

7. A method as claimed in claim 1 further comprising the step of weighting the recovered information using a scaling of that received time-dispersed signal.

8. A method as claimed in claim 7 above, wherein the soft decision information is obtained from progressively scaling over the interval of interest over which at least some of the recovered information is distributed.

9. A method as claimed in claim 1 further comprising the step of equalizing some of the time-dispersal effects before the step of weighting the recovered information.

10. A method as claimed in claim 1 above, wherein receiving comprises radio frequency reception.

11. The method of claim 1 wherein the weight is a soft decision information.

12. A method as claimed in claim 11 above, wherein the soft decision information is obtained from a partly equalized time-dispersed signal.

13. A method as claimed in claim 11 wherein the soft decision information is obtained from an absolute value of a matched filtered signal.

14. A method as claimed in claim 11 above, wherein the soft decision information is obtained from progressively scaling the soft decision information over an interval of interest.

15. A method as claimed in claim 11 above, wherein weighting comprises multiplication of the recovered information with the soft decision information.

16. A method of soft decision making comprising the steps of:

receiving a time-dispersed signal having a time-dispersal effect,

recovering information contained in the signal,

and weighting the recovered information by an absolute value of the received time-dispersed signal, after the time-dispersal effect has been accounted for.

17. An apparatus for soft decision making comprising:

means for receiving a time-dispersed signal having a time-dispersal effect, coupled with

means for recovering information contained in the time-dispersed signal,

and means for weighting the recovered information by using an absolute value of the time-dispersed signal, after the time-dispersal effect has been accounted for.

18. A method of soft decision making comprising the steps of:

receiving a time-dispersed signal having a time-dispersal effect,

recovering information contained in the time-dispersed signal,

and multiplying the recovered information by an absolute value of the time-dispersed signal, after equalizing the time-dispersal effect.

19. A method of soft decision making comprising the steps of:

radio reception of a time-dispersed signal,

recovering information contained in the time-dispersed signal,

and multiplying the recovered information by an absolute value of the time-dispersed signal, scaled over an interval over which at least part of the recovered information is distribute.

20. An apparatus for soft decision making comprising:

means for radio reception of a time-dispersed signal, coupled with

means for recovering information contained in the time-dispersed signal,

and means for multiplying the covered information by an absolute value of the time-dispersed signal.