Efficient trellis state metric normalization
AssigneeQUALCOMM Incorporated
InventorsElisha J. Ulmer, Jeremy M. Stein
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Abstract
A method and apparatus for normalizing a plurality of state-metric registers in a decoder using a trellis. The method includes determining an approximate minimum of respective state-metric values stored in the plurality of state-metric registers, and subtracting the approximate minimum from the values. Determining the approximate minimum preferably includes determining the minimum of a predetermined number of most significant bits in the plurality of state-metric registers.
Claims18
A method of normalizing a plurality of state-metric registers in a decoder using a trellis, comprising:
- determining an approximate minimum of respective state-metric values stored in the plurality of state-metric registers;
- and
- subtracting the approximate minimum from the values.
A method according to any of the preceding claims, wherein the predetermined number of most significant bits comprises between 30% and 60% of the number of bits in the register.
A state-metric calculation unit for use in a decoder which decodes using a trellis, comprising:
- a plurality of state-metric registers, which store respective state-metric values;
- a minimum calculation unit, which determines an approximate minimum of the plurality of registers;
- and
- a plurality of subtractors, which subtract the approximate minimum from the values in the plurality of registers.
Dependencies are inferred from the claim text.