Apparatus and Method for Trellis-Based Detection in a Communication System
First Claim
1. An apparatus, comprising:
- a processor; and
memory including computer program code,said memory and said computer program code configured to, with said processor, cause said apparatus to perform at least the following;
construct a trellis representing a transmitted signal formed from a plurality of symbols transmitted by a number of transmit antennas, each symbol having a constellation size, said trellis being formed of columns representing said number of transmit antennas and rows representing values of said plurality of symbols with nodes at intersections thereof;
form a log likelihood ratio at said nodes of said trellis as a log-sum of a number of exponential terms corresponding to a hypothesized transmitted bit value of 0 or 1 of said plurality of symbols, said number of exponential terms being limited by a function of a number of most likely paths of said trellis extending from each node of said trellis and said constellation size; and
form a list at each node of said trellis of a size limited to said number of said most likely paths of said trellis extending from each node of said trellis.
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Abstract
An apparatus for trellis-based detection in a communication system including a processor and memory having computer program code configured to construct a trellis representing a transmitted signal formed from a plurality of symbols, each having a constellation size, transmitted by a number of transmit antennas, and form a log likelihood ratio at nodes of the trellis as a log-sum of a number of exponential terms corresponding to a hypothesized transmitted bit value of the plurality of symbols. The number of exponential terms is limited by a number of most likely paths of the trellis extending from each node of the trellis and the constellation size. The processor and memory including computer program code are further configured to form a list at each node of the trellis of a size limited to the number of the most likely paths of the trellis extending from each node of the trellis.
11 Citations
20 Claims
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1. An apparatus, comprising:
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a processor; and memory including computer program code, said memory and said computer program code configured to, with said processor, cause said apparatus to perform at least the following; construct a trellis representing a transmitted signal formed from a plurality of symbols transmitted by a number of transmit antennas, each symbol having a constellation size, said trellis being formed of columns representing said number of transmit antennas and rows representing values of said plurality of symbols with nodes at intersections thereof; form a log likelihood ratio at said nodes of said trellis as a log-sum of a number of exponential terms corresponding to a hypothesized transmitted bit value of 0 or 1 of said plurality of symbols, said number of exponential terms being limited by a function of a number of most likely paths of said trellis extending from each node of said trellis and said constellation size; and form a list at each node of said trellis of a size limited to said number of said most likely paths of said trellis extending from each node of said trellis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A computer program product comprising a program code stored in a computer readable medium configured to:
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construct a trellis representing a transmitted signal formed from a plurality of symbols transmitted by a number of transmit antennas, each symbol having a constellation size, said trellis being formed of columns representing said number of transmit antennas and rows representing values of said plurality of symbols with nodes at intersections thereof; form a log likelihood ratio at said nodes of said trellis as a log-sum of a number of exponential terms corresponding to a hypothesized transmitted bit value of 0 or 1 of said plurality of symbols, said number of exponential terms being limited by a function of a number of most likely paths of said trellis extending from each node of said trellis and said constellation size; and form a list at each node of said trellis of a size limited to said number of said most likely paths of said trellis extending from each node of said trellis. - View Dependent Claims (12)
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13. A method, comprising:
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constructing a trellis representing a transmitted signal formed from a plurality of symbols transmitted by a number of transmit antennas, each symbol having a constellation size, said trellis being formed of columns representing said number of transmit antennas and rows representing values of said plurality of symbols with nodes at intersections thereof; forming a log likelihood ratio at said nodes of said trellis as a log-sum of a number of exponential terms corresponding to a hypothesized transmitted bit value of 0 or 1 of said plurality of symbols, said number of exponential terms being limited by a function of a number of most likely paths of said trellis extending from each node of said trellis and said constellation size; and forming a list at each node of said trellis of a size limited to said number of said most likely paths of said trellis extending from each node of said trellis. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification