Pilot pattern for observation-scalar MIMO-OFDM
View Patent ↗In an embodiment, a transmitter includes a transmission path configurable to generate first pilot clusters in response to a matrix, each first pilot cluster including a respective first pilot subsymbol in a first cluster position and a respective second pilot subsymbol in a second cluster position such that a vector formed by the first pilot subsymbols is orthogonal to a vector formed by the second pilot subsymbols, the matrix having a dimension related to a number of cluster positions in each of the first pilot clusters. For example, where such a transmitter transmits simultaneous orthogonal-frequency-division-multiplexed (OFDM) signals (e.g., MIMO-OFDM signals) over respective channels that may impart inter-carrier interference (ICI) to the signals due to Doppler spread, the pattern of the pilot symbols that compose the pilot clusters may allow a receiver of these signals to estimate the responses of these channels more accurately than conventional receivers.
1. An electronic device comprising:
a plurality of transmit paths each comprising:
a pilot generator configured to receive pilot information and generate pilot sub-symbols based upon the pilot information, the pilot sub-symbols being in a form of a pilot pattern matrix having a dual orthogonality such that each column of the pilot pattern matrix is orthogonal to each column of a pilot pattern matrix generated by pilot generators in each other transmit path, and each column of the pilot pattern matrix is orthogonal to each other column of the pilot pattern matrix in a given one of the plurality of transmit paths, each m th column of the pilot pattern matrix P pat (i) for the i th transmit path T i being constructed according to an equation:
P
pat
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i
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m
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where 0≦m≦Lp−1, Lp is the number of pilot sub-symbols, 0≦i≦N T −1 where N T is the total number of transmit paths, Ψ A (i) is an L p × N (i) matrix associated with the i th transmit path T i ,Ψ A (i) (m,p) is the value of the matrix element located in the m th row and p th column of the matrix Ψ A (i) ,S (i) (p) is the p th element of S (i) where S (i) denotes a set or vector corresponding to the i th transmit path T i , and where f (S (i) (p)) is given by an equation:
f (S (i) (p)) =[1 e −j2πΔf p (S (i) (p)) e −j2π2Δf p (S (i) (p)) e −j2π3Δf p (S (i) (p)) . . . e −j2π(N p −1)Δf p (S (i) (p)) ] T
where f (S (i) (p),Ψ B (i) (m,p)) denotes the column vector generated by circularly shifting the elements of the column vector f (S (i) (p)) downward a number of times equal to the value (m,p), which is the element in the m th row and the p th column of the matrix Ψ B (i) that is another L p × N (i) matrix associated with the i th transmit antenna T i , where the respective value of each element of Ψ B (i) is an integer that is between 0 and N p −1 inclusive, where 0<N(i)≦(N p /L)−1 where N p is a minimum number of pilot clusters L p and L is the number of transmission paths;
a pilot-subcarrier-coefficient generator coupled to said pilot generator and configured to generate from each pilot sub-symbol a respective complex frequency-domain coefficient for mapping to a respective pilot subcarrier;
a data generator configured to receive data information and generate data sub-symbols; and
a data-subcarrier-coefficient generator coupled to said data generator and configured to generate, from each data symbol, a respective complex frequency domain coefficient for mapping to a respective data subcarrier.
2. The electronic device of claim 1 , wherein each of said plurality of transmit paths further comprises an inverse Fourier transform (IFT) circuit coupled to said pilot-subcarrier-coefficient generator and said data-subcarrier-coefficient generator and configured to transform the pilot subcarrier coefficients and data subcarrier coefficients into a digital time-domain waveform.
3. The electronic device of claim 2 , wherein each of said plurality of transmit paths further comprises a digital-to-analog converter (DAC) coupled to said (IFT) circuit and configured to convert the digital time-domain waveform into an analog time-domain waveform.
4. The electronic device of claim 3 , wherein each of said plurality of transmit paths further comprises a modulator coupled to said DAC and configured to modulate a carrier signal with the analog time-domain waveform.
5. The electronic device of claim 4 , wherein each of said plurality of transmit paths further comprises an antenna coupled to said modulator.
6. The electronic device of claim 1 , wherein said plurality of transmit paths are for a given communication channel; and wherein said electronic device further comprises a further plurality of transmit paths corresponding to a further communications channel.
7. The electronic device of claim 6 , wherein a number of said plurality of transmit paths for the given communications channel is equal to a number of said further plurality of transmit paths for the further communications channel.
8. A system comprising:
a transmitter configured to transmit a modulated carrier signal;
a plurality of transmit paths each comprising:
a pilot generator configured to receive pilot information and generate pilot sub-symbols based upon the pilot information, the pilot sub-symbols being in a form of a pilot pattern matrix having a dual orthogonality such that each column of the pilot pattern matrix is orthogonal to each column of a pilot pattern matrix generated by pilot generators in each other transmit path, and each column of the pilot pattern matrix is orthogonal to each other column of the pilot pattern matrix in a given one of the plurality of transmit paths, each m th column of the pilot pattern matrix P pat (i) for the i th transmit path T i being constructed according to an equation:
P
pat
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N
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where 0≦m≦Lp−1, Lp is the number of pilot sub-symbols, 0≦i≦N T −1 where N T is the total number of transmit paths, Ψ A (i) is an L p ×N (i) matrix associated with the i th transmit path T i ,Ψ A (i) (m,p) is the value of the matrix element located in the m th row and p th column of the matrix Ψ A (i) ,S (i) (p) is the p th element of S (i) where S (i) denotes a set or vector corresponding to the i th transmit path T i , and where f (S (i) (p)) is given by an equation:
f (S (i) (p)) =[1 e −j2πΔf p (S (i) (p)) e −j2π2Δf p (S (i) (p)) e −j2π3Δf p (S (i) (p)) . . . e −j2π(N p −1)Δf p (S (i) (p)) ] T
where f (S (i) (p),Ψ B (i) (m,p)) denotes the column vector generated by circularly shifting the elements of the column vector f (S (i) (p)) downward a number of times equal to the value Ψ B (i) (m,p), which is the element in the m th row and the p th column of the matrix Ψ B (i) that is another L p ×N (i) matrix associated with the i th transmit antenna T i , where the respective value of each element of Ψ B (i) is an integer that is between 0 and N p −1 inclusive, where 0<N(i)≦(N p /L)−1 where N p is a minimum number of pilot clusters L p and L is the number of transmission paths;
a pilot-subcarrier-coefficient generator coupled to said pilot generator and configured to generate from each pilot sub-symbol a respective complex frequency-domain coefficient for mapping to a respective pilot subcarrier;
a data generator configured to receive data information and generate data sub-symbols; and
a data-subcarrier-coefficient generator coupled to said data generator and configured to generate, from each data symbol, a respective complex frequency domain coefficient for mapping to a respective data subcarrier; and
a receiver operatively coupled to said transmitter and configured to receive the modulated carrier signal.
9. The system of claim 8 , wherein each of said plurality of transmit paths further comprises an inverse Fourier transform (IFT) circuit coupled to said pilot-subcarrier-coefficient generator and said data-subcarrier-coefficient generator and configured to transform the pilot subcarrier coefficients and data subcarrier coefficients into a digital time-domain waveform.
10. The system of claim 9 , wherein each of said plurality of transmit paths further comprises a digital-to-analog converter (DAC) coupled to said IFT circuit and configured to convert the digital time-domain waveform into an analog time-domain waveform.
11. The system of claim 10 , wherein each of said plurality of transmit paths further comprises a modulator coupled to said DAC and configured to modulate a carrier signal with the analog time-domain waveform.
12. The system of claim 11 , wherein each of said plurality of transmit paths further comprises an antenna coupled to said modulator and configured to transmit the modulated carrier signal for reception by said receiver.
13. The system of claim 9 , wherein said plurality of transmit paths are for a given communication channel; and wherein said system further comprises a further plurality of transmit paths corresponding to a further communications channel.
14. The system of claim 13 , wherein a number of said plurality of transmit paths for the given communications channel is equal to a number of said further plurality of transmit paths for the further communications channel.
15. A method of communicating over a plurality of transmit paths, the method comprising for each of the plurality of transmit paths:
using a pilot generator to receive pilot information and generate pilot sub-symbols based upon the pilot information, the pilot sub-symbols being in a form of a pilot pattern matrix having a dual orthogonality such that each column of the pilot pattern matrix is orthogonal to each column of a pilot pattern matrix generated by pilot generators in each other transmit path, and each column of the pilot pattern matrix is orthogonal to each other column of the pilot pattern matrix in a given one of the plurality of transmit paths, wherein each m th column of the pilot pattern matrix P pat (i) for the i th transmit path T i being constructed according to an equation:
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where 0≦m≦Lp−1, Lp is the number of pilot sub-symbols, 0≦i≦N T −1 where N T is the total number of transmit paths, Ψ A (i) is an L p ×N (i) matrix associated with the i th transmit path T i ,Ψ A (i) (m,p) is the value of the matrix element located in the m th row and p th column of the matrix Ψ A (i) ,S (i) (p) is the p th element of S (i) where S (i) denotes a set or vector corresponding to the i th transmit path T i , and where f (S (i) (p)) is given by an equation:
f (S (i) (p)) =[1 e −j2πΔf p (S (i) (p)) e −j2π2Δf p (S (i) (p)) e −j2π3Δf p (S (i) (p)) . . . e −j2π(N p −1)Δf p (S (i) (p)) ] T
where f (S (i) (p),Ψ B (i) (m,p)) denotes the column vector generated by circularly shifting the elements of the column vector f (S (i) (p)) downward a number of times equal to the value Ψ B (i) (m, p), which is the element in the m th row and the p th column of the matrix Ψ B (i) that is another L p ×N (i) matrix associated with the i th transmit antenna T i , where the respective value of each element of Ψ B (i) is an integer that is between 0 and N p −1 inclusive, where 0<N(i)≦(N p /L)−1 where N p is a minimum number of pilot clusters L p and L is the number of transmission paths;
using a pilot-subcarrier-coefficient generator coupled to the pilot generator to generate from each pilot sub-symbol a respective complex frequency-domain coefficient for mapping to a respective pilot subcarrier;
using a data generator to receive data information and generate data sub-symbols; and
using a data-subcarrier-coefficient generator coupled to the data generator to generate, from each data symbol, a respective complex frequency domain coefficient for mapping to a respective data subcarrier.
16. A non-transitory computer readable medium for an electronic device comprising a plurality of transmit paths, the non-transitory computer readable medium comprising computer-executable instructions to cause the electronic device to perform operations comprising, for each of the plurality of transmit paths:
generating pilot sub-symbols based upon received pilot information, the pilot sub-symbols being in a form of a pilot pattern matrix having a dual orthogonality such that each column of the pilot pattern matrix is orthogonal to each column of a pilot pattern matrix generated by pilot generators in each other transmit path, and each column of the pilot pattern matrix is orthogonal to each other column of the pilot pattern matrix in a given one of the plurality of transmit paths, each m th column of the pilot pattern matrix P pat (i) for the i th transmit path T i being constructed according to an equation:
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where 0≦m≦Lp−1, Lp is the number of pilot sub-symbols, 0≦i≦N T −1 where N T is the total number of transmit paths, Ψ A (i) is an L p ×N (i) matrix associated with the i th transmit path T i ,Ψ A (i) (m,p) is the value of the matrix element located in the m th row and p th column of the matrix Ψ A (i) ,S (i) (p) is the p th element of S (i) where S (i) denotes a set or vector corresponding to the i th transmit path T i , and where f (S (i) (p)) is given by an equation:
f (S (i) (p)) =[1 e −j2πΔf p (S (i) (p)) e −j2π2Δf p (S (i) (p)) e −j2π3Δf p (S (i) (p)) . . . e −j2π(N p −1)Δf p (S (i) (p)) ] T
where f (S (i) (p),Ψ B (i) (m,p)) denotes the column vector generated by circularly shifting the elements of the column vector f (S (i) (p)) downward a number of times equal to the value Ψ B (i) (m,p), which is the element in the m th row and the p th column of the matrix Ψ B (i) that is another L p ×N (i) matrix associated with the i th transmit antenna T i , where the respective value of each element of Ψ B (i) is an integer that is between 0 and N p −1 inclusive, where 0<N(i)≦(N p /L)−1 where N p is a minimum number of pilot clusters L p and L is the number of transmission paths;
generating from each pilot sub-symbol a respective complex frequency-domain coefficient for mapping to a respective pilot subcarrier;
generating data sub-symbols; and
generating, from each data symbol, a respective complex frequency domain coefficient for mapping to a respective data subcarrier.