Apparatus and method for detecting feedback information in a wireless communication system
An apparatus and method for determining feedback information detection in a broadband wireless communication system are provided. In the detection determining apparatus, a demodulator correlates each of tiles carrying received feedback information with an orthogonal vector including a pilot symbol in each possible codeword, each tile being a predetermined number of subcarriers, and calculates the squares of the absolute values of the correlations. A codeword correlation calculator sums the squares of the absolute value of the correlations of the tiles for each possible codeword. A detection decider determines whether to perform detection on the feedback information based on the maximum of the sums.
1. An apparatus for determining feedback information detection in a wireless communication system, comprising:
a de-allocator for separating each tile from feedback information; and
at least one correlator for correlating a plurality of modulation symbols and a pilot symbol of each tile with a plurality of symbols, corresponding to a codeword, and a pilot symbol for each codeword; and
a channel decoder for summing squares of absolute values of the correlated symbols and pilot symbol for each codeword and determining a codeword having a maximum sum;
wherein the at least one correlator calculates squares of absolute values of the correlated symbols and pilot symbol;
wherein the channel decoder comprises a detection decider for deciding whether to perform detection on the feedback information, and
wherein the detection decider determines that the feedback information is reliable if a difference between a maximum of the sums and an average of the sums is greater than or equal to a predetermined threshold, and the detection decider determines that the feedback information is not reliable if the difference between the maximum of the sums and the average of the sums is less than the predetermined threshold.
2. The apparatus of claim 1 , wherein a number of the at least one correlator for each tile is equal to a number of modulation symbols and pilot symbol per tile.
3. The apparatus of claim 1 , wherein the detection decider decides to perform detection on the feedback information if the feedback information is reliable, and the detection decider decides not to perform detection on the feedback information if the feedback information is not reliable.
4. The apparatus of claim 1 , wherein the detection decider decides whether to perform detection by
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where Y m,k denotes a symbol received on a k th subcarrier in an m th tile, Y′ m,k′ denotes a pilot symbol received on a k′ th subcarrier in the m th tile, X n,m,k denotes a orthogonal vector (symbol) corresponding to an n th codeword for the k th subcarrier in the m th tile, Q m,k′ denotes a transmitted pilot symbol for the k′ th subcarrier of the m th tile, n denotes a codeword index (e.g. 2 4 (m=0, . . . , 15)), m denotes a tile index (m=0, 1, . . . , 5), k denotes a subcarrier index (k=0, 1, . . . 7), and k′ denotes a pilot subcarrier index and superscript denotes complex conjugate operation.
5. The apparatus of claim 3 , further comprising a detector for performing detection on the feedback information, if the feedback information is reliable.
6. A method of determining feedback information detection in a wireless communication system, comprising the steps of:
separating each tile from-a feedback information;
correlating a plurality of modulation symbols and a pilot symbol of each tile with a plurality of symbols, corresponding to a codeword, and a pilot symbol for each codeword;
summing squares of absolute values of the correlated symbols and pilot symbol for each codeword;
selecting a codeword corresponding to a maximum of the sums of the squares of the absolute values of the correlated symbols and pilot symbol;
calculating a difference between the maximum of the sums and an average sum; and
determining whether to perform detection on the feedback information by comparing the difference with a predetermined threshold.
7. The method of claim 6 , further comprising performing detection on the feedback information, if the difference between the maximum of the sums and the average of the sums is greater than or equal to than the predetermined threshold.
8. The method of claim 6 , further comprising discarding the feedback information, if the difference between the maximum of the sums and the average of the sums is less than the predetermined threshold.
9. The method of claim 6 , wherein the detection determining step comprises determining whether to perform detection by
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where Y m,k denotes a symbol received on a k th subcarrier in an m th tile, Y′ m,k′ denotes a pilot symbol received on a k′ th subcarrier in the m th tile, X n,m,k denotes a orthogonal vector (symbol) corresponding to an n th codeword for the k th subcarrier in the m th tile, Q m,k′ denotes a transmitted pilot symbol for the k′ th subcarrier of the m th tile, n denotes a codeword index (e.g. 2 4 (m=0, . . . , 15)), m denotes a tile index (m=0, 1, . . . , 5), k denotes a subcarrier index (k=0, 1, . . . 7), and k′ denotes a pilot subcarrier index and superscript * denotes complex conjugate operation.