Method and apparatus for compensation of linear or nonlinear intersymbol interference and noise correlation in magnetic recording channels
First Claim
1. A method for decoding a received digital signal transmitted over a channel, said method comprising:
- generating N most likely paths representing said received digital signal, each of said N most likely paths having a first type metric associated therewith, said first type metric based on a simplified model of said channel; and
postprocessing said N most likely paths for a final most likely path representative of said received digital signal, said most likely path indicated by a best second type metric, said best second type metric based on a comprehensive model of said channel which accounts for at least one source of channel information from a group consisting of intersymbol interference and nonlinearity.
10 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for decoding a signal in the presence of linear or nonlinear interference, correlated noise or a combination thereof. The method involves a concatenated decoder comprising an inner decoder and a postprocessor. N most likely paths are generated by the inner decoder, or a combination of the inner decoder and an error event generator. These paths are then presented to the postprocessor which computes metrics for each path based on information about the signal, not considered by the inner decoder. These metrics can be based on linear or nonlinear model of the channel and optionally, a noise whitened signal for noise decorrelation. The path with the best metric is selected as the concatenated decoder output. The postprocessor can also be implemented in the presence of channel codes. It is also shown that the postprocessor is especially suited for a trellis implementation. When applied to magnetic recording channels, the method of the present invention allows for increased recording capacity. In addition, the present invention requires less computation and results in a reduction of the power dissipation of about two orders of magnitude compared to alternative approaches.
145 Citations
26 Claims
-
1. A method for decoding a received digital signal transmitted over a channel, said method comprising:
-
generating N most likely paths representing said received digital signal, each of said N most likely paths having a first type metric associated therewith, said first type metric based on a simplified model of said channel; and postprocessing said N most likely paths for a final most likely path representative of said received digital signal, said most likely path indicated by a best second type metric, said best second type metric based on a comprehensive model of said channel which accounts for at least one source of channel information from a group consisting of intersymbol interference and nonlinearity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. A concatenated decoder for decoding a received digital signal transmitted over a channel comprising:
-
an inner N-best Viterbi decoder; and a postprocessor comprising computer implemented means for computing a metric based on a comprehensive model of said channel, said comprehensive model accounting for at least one source of channel information from a group consisting of intersymbol interference and nonlinearity; and computer implemented means for selecting a most likely path representative of said received digital signal, based on said metric, wherein said postprocessor further comprises means for adaptive channel estimation of characteristics of said channel. - View Dependent Claims (17)
-
-
18. A concatenated decoder for decoding a received digital signal transmitted over a channel, comprising:
-
an inner decoder for generating N most likely paths representing said received digital signal, each of said N most likely paths having a first type metric associated therewith, said first type metric based on a simplified model of said channel; and a postprocessor for determining a final most likely path from said N most likely paths representative of said received digital signal, said most likely path indicated by a best second type metric, said second type metric based on a comprehensive model of said channel which accounts for at least one source of channel information from the group consisting of intersymbol interference and nonlinearity. - View Dependent Claims (19, 20)
-
-
21. A method for decoding a received digital signal transmitted over a channel, said method comprising:
-
generating a single tentative most likely path representative of said received digital signal based on a simplified model of said channel; computing a finite number of most likely error events based on said simplified model of said channel using a trellis implementation; generating N most likely paths by combining said single tentative most likely path with said finite number of most likely error events using said trellis style implementation; computing a second type metric based on a comprehensive model of said channel; and generating a single most likely path based on said second type metric using said trellis style implementation. - View Dependent Claims (22, 23, 24, 25, 26)
-
Specification