Method for estimating spatial parameters of transmission channels by estimating a spatial covariance matrix
First Claim
1. A method for determining by direct calculation from sampling values measured in an upward direction at the base station, subscriber station-specific spatial covariance matrices of transmission channels between a central station and a predetermined number of subscriber stations of a communication system, wherein the central station includes an antenna consisting of several individual sensors, the method comprising the following steps:
- transmitting data sequences respectively from said subscriber stations to said central station via said transmission channels, each of said data sequences containing a known data sequence component;
chronologically sampling values of the individual sensors at the central station and compiling the sampled values as a predetermined number of reception vectors;
determining a channel impulse response for each subscriber station for a transmission path between each subscriber station and each individual sensor of the antenna, dependant on said predetermined number of reception vectors and the reception known data sequence components, without implementing a direction estimate; and
for each subscriber station, correlating at least two channel impulse responses which correspond to transmission paths between said subscriber station and two of the individual sensors of the antenna and assigning the two channel impulse responses to a column number and a row number of a spatial covariance matrix for said subscriber station.
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Abstract
A method for estimating spatial parameters of a transmission channel between radio stations in communication systems is provided where it is assumed that an antenna means consisting of several individual radiators is allocated to a radio station. With the aid of these individual radiators, sampled values of a receive signal are determined, from which a receive matrix is formed. An estimated value for the spatial covariance matrix of the transmission channel is determined by means of matrix multiplication of the receive matrix with the conjugated complex transposed receive matrix. If several connections are active simultaneously, connection-individual channel impulse responses based on training sequences or estimated values for the transmitted data, are determined from the sampled values, which channel impulse responses are used to determine the connection-individual spatial covariance matrices.
94 Citations
11 Claims
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1. A method for determining by direct calculation from sampling values measured in an upward direction at the base station, subscriber station-specific spatial covariance matrices of transmission channels between a central station and a predetermined number of subscriber stations of a communication system, wherein the central station includes an antenna consisting of several individual sensors, the method comprising the following steps:
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transmitting data sequences respectively from said subscriber stations to said central station via said transmission channels, each of said data sequences containing a known data sequence component;
chronologically sampling values of the individual sensors at the central station and compiling the sampled values as a predetermined number of reception vectors;
determining a channel impulse response for each subscriber station for a transmission path between each subscriber station and each individual sensor of the antenna, dependant on said predetermined number of reception vectors and the reception known data sequence components, without implementing a direction estimate; and
for each subscriber station, correlating at least two channel impulse responses which correspond to transmission paths between said subscriber station and two of the individual sensors of the antenna and assigning the two channel impulse responses to a column number and a row number of a spatial covariance matrix for said subscriber station. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
recording the channel impulse responses for each subscriber station as time-discrete sampled sets; arranging the time-discrete sampled sets as row vectors one over the other to provide a channel impulse response matrix for each subscriber station;
generating a conjugated complex transpose response matrix for each subscriber station;
and the method further comprises the step of;
estimating a value of the spatial covariance matrix for each subscriber station by multiplying the channel impulse response matrix for each subscriber station by the conjugated complex transpose response matrix for each subscriber station.
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3. The method of claim 2 further comprising the following step:
dividing the estimated value of the spatial covariance for each subscriber station by a transmission power of said subscriber station.
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4. The method of claim 1 further comprising the following steps:
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transmitting predetermined symbols from each subscriber station to the central station, the transmitted symbols being specific to each subscriber station; and
at the central station, assigning the transmitted symbols to the channel impulse responses for each subscriber station.
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5. The method of claim 1, further comprising the following steps:
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transmitting predetermined symbols from each subscriber station to the central station, the transmitted symbols being specific to each subscriber station;
at the central station, correlating the transmitted symbols from each subscriber station to the reception vectors for said subscriber station; and
assigning the transmitted symbols to the channel impulse responses for each subscriber station.
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6. The method of claim 1 further comprising the following step:
adjusting the number reception vectors used based on channel transmission coefficients.
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7. The method of claim 1 wherein the chronological sampling step is carried out over a predetermined number of sampling times for each subscriber station, and
the correlating step is carried out for each sampling time for each subscriber station thereby generating a predetermined number of spatial covariance matrices for each subscriber station, and the correlating stop further comprises averaging the covariance matrices generated for each subscriber station to provide an improved estimated value of the spatial covariance matrix specific to each subscriber station. -
8. The method of claim 7 wherein the predetermined number sampling times corresponds to the channel transmission coefficients.
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9. The method of claim 7 wherein averaging step further comprises multiplying the spatial covariance matrices for sampling periods that have taken place at an earlier time influence by a factor of less than one and multiplying the spatial covariance matrices that have taken place at a later time by a factor of greater than one.
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10. The method of claim 9 wherein the averaging step further comprises exponential forgetting.
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11. The method of claim 10 wherein a forgetting factor corresponds to the channel transmission coefficients.
Specification