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US 11,677,420 B1Granted
Externalizing inter-symbol interference data in a data channel
AssigneeWestern Digital Technologies, Inc.
InventorsRichard Galbraith, Jonas Goode, Iouri Oboukhov, Niranjay Ravindran
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Abstract
Example systems, read channel circuits, data storage devices, and methods to use inter-symbol interference message passing (ISI-MP) data in a read channel are described. The read channel circuit includes a soft output detector, such as a soft output Viterbi algorithm (SOVA) detector, configured to determine both the first most likely and second most likely sets of symbols and output inter-symbol interference data based on the adjacent symbols and corresponding ISI in each set of symbols. The inter-symbol interference data may be used by an ISI-MP circuit configured to model ISI-MP and provide feedback to an iterative decoder during local iterations.
Claims20
A read channel circuit, comprising:
- a soft output detector configured to:
- receive an input signal comprising digital bit samples from an analog data signal;
- determine a first set of symbols with a first likelihood within a period of the input signal;
- determine a second set of symbols with a second likelihood within the period of the input signal;
- determine first inter-symbol interference data for adjacent symbols in the first set of symbols;
- determine second inter-symbol interference data for adjacent symbols in the second set of symbols;
- output soft information for the first set of symbols;
- and
- output the first inter-symbol interference data and the second inter-symbol interference data;
- an inter-symbol interference message passing model configured to:
- receive the first inter-symbol interference data and the second inter-symbol interference data from the soft output detector;
- and
- determine a change in the soft information for the first set of symbols based on:
- the first inter-symbol interference data;
- the second inter-symbol interference data;
- and
- at least one error event;
- and
- output the change in the soft information for the first set of symbols;
- and
- an iterative decoder configured to use the change in the soft information for iterative decoding of the input signal to output a decoded data unit based on the input signal.
18 more elements
A method comprising:
- receiving, by a soft output detector, an input signal comprising digital bit samples from an analog data signal;
- determining, by the soft output detector, a first set of symbols with a first likelihood within a period of the input signal;
- determining, by the soft output detector, a second set of symbols with a second likelihood within the period of the input signal;
- determining first inter-symbol interference data for adjacent symbols in the first set of symbols;
- determining second inter-symbol interference data for adjacent symbols in the second set of symbols;
- outputting soft information for the first set of symbols;
- outputting the first inter-symbol interference data and the second inter-symbol interference data;
- receiving, by an inter-symbol interference message passing circuit, the first inter-symbol interference data and the second inter-symbol interference data from the soft output detector;
- determining a change in the soft information for the first set of symbols based on:
- the first inter-symbol interference data;
- the second inter-symbol interference data;
- and at least one error event;
- outputting, by the inter-symbol interference message passing circuit, the change in the soft information for the first set of symbols;
- and
- using, by an iterative decoder, the change in the soft information for iterative decoding of the input signal to output a decoded data unit based on the input signal.
12 more elements
A system comprising:
- a soft output detector configured to:
- determine a first set of symbols with a first likelihood within a period of an input signal, wherein the input signal comprises digital bit samples from an analog data signal;
- determine a second set of symbols with a second likelihood within the period of the input signal;
- determine first inter-symbol interference data for adjacent symbols in the first set of symbols;
- determine second inter-symbol interference data for adjacent symbols in the second set of symbols;
- output soft information for the first set of symbols;
- and
- output the first inter-symbol interference data and the second inter-symbol interference data;
- an inter-symbol interference message passing circuit configured to determine a change in the soft information based on at least one error event bubble, wherein:
- the first inter-symbol interference data and the second inter-symbol interference data includes the at least one error event bubble;
- the at least one error event bubble has a length corresponding to a number of adjacent symbols in a trellis of the soft output detector;
- error events with a length greater than one symbol generate inter-symbol interference;
- and
- the first inter-symbol interference data and the second inter-symbol interference data describe inter-symbol interference between adjacent symbols in the at least one error event bubble;
- and
- an iterative decoder configured to:
- receive the change in soft information for an iteration of processing a parity decision matrix of the iterative decoder;
- and
- use the change in the soft information for iterative decoding of the first set of symbols to output a decoded data unit based on the input signal.
16 more elements
Dependencies are inferred from the claim text.