Method and apparatus for delayed recursion decoder
AssigneeIntersymbol Communications, Inc.
InventorsRajamohana Hegde, Andrew Singer, Jacob Janovetz
Life of this patent
Estimating the term…
Abstract
A high-speed maximum likelihood sequence estimation method and device. The method includes identifying candidate paths through a state trellis based on a group of observed data, where each candidate path corresponds to a best path through a trellis beginning at one of a possible prior states (and corresponding prior data bit or bits), and then selecting one of the paths based on candidate sequence selection information, typically prior state decisions (e.g., data symbols in the form of one or more bits). The path selection, in turn, provides decoding of symbols and data bit information for use in selecting one of the candidate paths in a subsequent stage.
Claims27
A method for estimating a sequence of symbols, wherein the symbols conform to predetermined valid symbol sequences, comprising the steps:
- forming at least two predetermined groups of valid sequences, wherein each group is formed based on possible initial states and includes all possible valid sequences originating from the respective initial states;
- receiving a set of symbol measurements;
- identifying a candidate sequence for each group of valid sequences, wherein the candidate sequence is a valid sequence from its respective group that is closest to the set of symbol measurements, wherein each candidate sequence has corresponding decision information, and wherein each candidate sequence is identified by forming a set of error metrics for each symbol in the set of received symbols, and using the sets of error metrics to select sequences in time-reverse order;
- and
- determining at least one output decision by selecting a group and corresponding decision information from the identified candidate sequence in response to candidate sequence selection information.
A method for estimating a sequence of symbols, comprising the steps:
- forming groups of paths through a trellis based on the initial states of the paths;
- forming sets of sequential samples of symbols, wherein the sets comprise at least a first set of samples and a next set of samples;
- for each set of samples, determining a plurality of minimum error paths and corresponding candidate decision information, wherein each group has a minimum error path and corresponding candidate decision information;
- selecting a group corresponding to the first set of samples and its minimum error path and its corresponding decision information, where the selection is based on prior state information;
- and
- using at least a portion of the selected corresponding decision information to select a group corresponding to the next set of samples and its corresponding decision information.
A decoder comprising:
- at least one sequence error estimator comprising an input to receive symbol error metrics and a plurality of candidate path outputs and a plurality of interconnected selectors and adders, wherein said at least one sequence error estimator identifies a plurality of candidate paths in time reverse order and decision information corresponding to each of said candidate paths, and provides said decision information at said candidate path outputs;
- and,
- a selector connected to said at least one sequence error estimator, said selector having inputs connected to said candidate path outputs, a selector output for providing an output decision, and a selection input for determining which of said inputs is interconnected to said selector output, thereby providing an output decision corresponding to the decision information on said interconnected input.
A decoder device comprising:
- a branch error metric block for generating incremental error estimates;
- a plurality of candidate path identification blocks, each of said candidate path identification blocks providing a set of outputs;
- and,
- a plurality of selection devices, wherein each one of said plurality of selection devices is connected to said set of outputs of each one of said plurality of candidate path identification blocks, where each selection device provides data outputs, and wherein the data outputs of each of said plurality of selection devices is used to select the data outputs of another of said plurality of selection devices.
A decoder device comprising:
- means for generating branch error metric values;
- at least one decoding means connected to said means for generating branch error metrics, wherein each decoding means comprises:
- a sequence identification means for identifying a set of candidate sequences in response to said branch error metrics, wherein each candidate sequence within said set of candidate sequences has associated candidate decision information;
- and
- a selecting means for receiving said associated candidate decision information, and for providing output decision information, said output decision information being generated in response to said associated candidate decision information, and output decision information from a selecting means of another decoding means.
A method of recovering information from a plurality of state observations of system comprising the steps:
- identifying a candidate sequence for each initial state of a system having a plurality of initial states, wherein the candidate sequence for each initial state is identified in time-reverse order, and wherein each candidate sequence has an associated candidate set of decision information;
- receiving initial state decision information;
- and
- selecting a single candidate set of decision information from the candidate sets in response to the received initial state information.
Dependencies are inferred from the claim text.