Sphere decoding apparatus
First Claim
1. A method for list sphere decoding comprising:
- receiving at a receiver at least one codeword sent over a multiple-input multiple-output (MIMO) channel, wherein the at least one codeword comprises a plurality of layers, each layer comprising a constellation point of a plurality of candidate constellation points;
for each layer, computing a state cost metric using said codeword for each constellation point of the at least one layer, and selecting preferred states of the at least one layer whose state cost metrics meet first preferred criteria; and
for each of a plurality of constellation points of said layer, computing a state cost metric using said codeword for each transition from a preferred constellation point of said layer to each constellation point of a following layer, and selecting preferred transitions to said following layer whose state cost metrics meet second preferred criteria.
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Abstract
Methods and apparatuses for decoding codewords received over a MIMO channel are provided. According to one aspect of the disclosure, a cost function is computed for each constellation point of an Mth rank or spatial layer, and Ncand of those constellation points having minimum cost are preserved as candidate points, where Ncand is a parameter specified to the decoding algorithm. In addition, a cost function may be computed for all possible transitions from the Ncand candidate points of the Mth rank to all possible constellation points of the (M−1)th spatial layer, and Ncand of those transitions having minimum cost are preserved as candidate points. The process is repeated for all spatial layers, resulting in the identification of Ncand candidate codewords and their associated cost functions.
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Citations
38 Claims
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1. A method for list sphere decoding comprising:
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receiving at a receiver at least one codeword sent over a multiple-input multiple-output (MIMO) channel, wherein the at least one codeword comprises a plurality of layers, each layer comprising a constellation point of a plurality of candidate constellation points; for each layer, computing a state cost metric using said codeword for each constellation point of the at least one layer, and selecting preferred states of the at least one layer whose state cost metrics meet first preferred criteria; and for each of a plurality of constellation points of said layer, computing a state cost metric using said codeword for each transition from a preferred constellation point of said layer to each constellation point of a following layer, and selecting preferred transitions to said following layer whose state cost metrics meet second preferred criteria. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A decoding method comprising:
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receiving a codeword comprising a plurality of symbols, each symbol corresponding to at least one of a plurality of candidate constellation points; for a first symbol; computing a cost metric for each candidate constellation point of said first symbol; storing in a memory only those candidate constellation points whose computed cost metrics meet first preferred criteria; for each following symbol, and for each candidate constellation point previously stored in said memory for the symbol immediately preceding said following symbol; computing a cost metric for each candidate transition from said previously stored candidate constellation point to a candidate constellation point of said following symbol; and storing in said memory only those candidate transitions whose computed cost metrics meet second preferred criteria. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A decoder apparatus comprising:
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a receiver configured to receive at least one codeword sent over a multiple-input multiple-output (MIMO) channel, wherein the at least one codeword comprises a plurality of layers, each layer comprising a constellation point selected from a plurality of candidate constellation points; and a processor configured to, for at least one layer, compute a constellation point metric for the at least one layer, and to select preferred constellation points of the at least one layer whose state cost metrics meet first preferred criteria;
the processor further configured to compute a constellation point cost metric for each transition from a preferred constellation point of the layer to each constellation point of a following layer, and selecting preferred transitions to said following layer whose constellation point cost metrics meet second preferred criteria. - View Dependent Claims (31, 32, 33, 34, 35, 36)
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37. A processor readable media comprising instructions thereon that may be utilized by a processor, the instructions comprising:
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instructions for a first symbol, of a codeword comprising a plurality of symbols, each symbol corresponding to at least one of a plurality of candidate constellation points, computing a cost metric for each candidate constellation point of said first symbol; instructions for storing in a memory only those candidate constellation points whose computed cost metrics meet first preferred criteria; and instructions, for each following symbol and for each candidate constellation point previously stored in said memory for the symbol immediately preceding said following symbol, computing a cost metric for each candidate transition from said previously stored candidate constellation point to a candidate constellation point of said following symbol. - View Dependent Claims (38)
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Specification