Abstract: A method and apparatus for channel estimation based on extracting channel information, including noise spectral density, from a received signal, and advantageously exploiting that information for improved channel estimation accuracy. One embodiment is directed to a method of generating channel estimates in a wireless communication receiver, for processing a received communication signal. The method includes generating first channel estimates from a set of pilot observations obtained from the received communication signal, using a first channel estimation process that is not dependent on knowledge of channel statistics. The method further includes estimating channel statistics and a noise variance from the first channel estimates, and generating second channel estimates from the set of pilot observations, the estimated channel statistics, and the estimated noise variance, using a second channel estimation process that is dependent on knowledge of the channel statistics.

Abstract: The described method characterizes scattering objects in a wireless channel. The present invention determines non-equally spaced path delays and Doppler parameters for a plurality of scattering objects in a wireless channel. More particularly, a frequency-to-time transform applied to a plurality of OFDM pilot samples received over a plurality of OFDM symbol periods generates a set of non-equally spaced path delays and a set of associated complex delay coefficients. Further, a time-to-frequency transform applied to the complex delay coefficients determined for one path delay over multiple OFDM symbol periods generates a set of Doppler parameters comprising a plurality of non-equally spaced Doppler frequencies and their corresponding scattering coefficients for that path delay.

Abstract: A UE in a wireless communication network transmits succinct, direct channel state information to the network, enabling coordinated multipoint calculations such as joint processing, without substantially increasing uplink overhead. The UE receives and processes reference symbols over a set of non-uniformly spaced sub-carriers, selected according to a scheme synchronized to the network. The frequency response for each selected sub-carrier is estimated conventionally, and the results quantized and transmitted to the network on an uplink control channel. The non-uniform sub-carrier selection may be synchronized to the network in a variety of ways.

Abstract: A method of variable rate vector quantization reduces the amount of channel state feedback. Channel coefficients of a communication channel are determined and second order statistics (e.g., variances) of the channel taps are computed). Bit allocation for the channel taps are determined based on the coefficients statistics. The channel taps are individually quantized at rates determined based on said bit allocations.

Abstract: A UE in a wireless communication network transmits succinct, direct channel state information to the network, enabling coordinated multipoint calculations such as joint processing, without substantially increasing uplink overhead. The UE receives and processes reference symbols over a set of non-uniformly spaced sub-carriers, selected according to a scheme synchronized to the network. The frequency response for each selected sub-carrier is estimated conventionally, and the results quantized and transmitted to the network on an uplink control channel. The non-uniform sub-carrier selection may be synchronized to the network in a variety of ways.

Abstract: In MIMO systems, two or more transmit signals are transmitted from different antenna clusters having one or more transmit antennas each. A precoding circuit weight the transmit signals transmitted from each transmit antenna using a common set of frequency independent antenna weights for all antenna clusters. The antenna weights are computed based on correlations between transmit antennas in the same antenna cluster.

Abstract: A receiver and a method are described herein for reducing an amount of channel state information related to a transmit channel correlation matrix ?TX that is feedback to a transmitter. In addition, to a transmitter and a method are described herein for reconstructing the transmit channel correlation matrix ?TX using the reduced channel state feedback information received from the receiver.

Abstract: In MIMO systems, two or more transmit signals are transmitted from different antenna clusters having one or more transmit antennas each. A precoding circuit weight the transmit signals transmitted from each transmit antenna using a common set of frequency independent antenna weights for all antenna clusters. The antenna weights are computed based on correlations between transmit antennas in the same antenna cluster.

Abstract: The present invention relates to a method and arrangement for reducing feedback data in a communication system, said communication system comprising a number of transmitter antennas, n?, and a number of receiver antennas, nR, for parallel spatially independent transmission and reception of signals, wherein a channel response is represented by a matrix (G) containing nR×n? complex variables. The method comprises the steps of: decomposing an expression of said channel response matrix (G) into products of a unitary transform (V), nR×nT diagonal matrix (?) and a conjugate transpose of a unitary matrix (W). Choosing said unitary matrix (W) such that its diagonal elements are real, substituting said channel response matrix (G) with a representative subset of elements in said decomposed expression of said channel response matrix (G), said representative subset comprising diagonal of a first matrix (?) and lower triangle of a second matrix (W) excluding the diagonal.

Abstract: A method for determining antenna weights for use in transmitting data from a plurality of base stations to a user device is disclosed. The antenna weights are determined using an input covariance matrix (S), and the input covariance matrix is determined subject to a predetermined power constraint and a predetermined, non-zero interference constraint.

Abstract: A communication device is described herein that has control (or at least partial control) over which virtual antenna(s) in one or more base stations to use for transmissions. In one embodiment, the mobile phone performs the following steps: (1) receives an antenna subset list (from the scheduling unit) which identifies a configuration of virtual antennas that is associated with the base station(s); (2) uses the antenna subset list to select which virtual antenna(s) in the configuration of virtual antennas to use for transmissions; and (3) sends an antenna selection signal (to the scheduling unit) which contains information that instructs/requests the base station(s)/scheduling unit to use the selected virtual antenna(s) for transmissions.

Abstract: The present invention uses newly received signal samples to update previously determined scatterer parameters, and therefore, reduces the processing effort required for characterizing scattering objects in a wireless channel. Broadly, the present invention determines a first set of scatterer parameters based on signal samples derived from signals received during one or more previous time intervals, and determines an updated set of scatterer parameters for a subsequent time interval based on the first set of scatterer parameters and the new signal samples. In one exemplary embodiment, the receiver uses a continuous sequential update process, e.g., a per-symbol-period inverse Prony process, to update the scatterer parameters. In another exemplar embodiment, the receiver uses an integrated Doppler approach to update the scatterer parameters.

Abstract: A wireless communication receiver improves signal impairment correlation estimation in MIMO/MISO systems by considering different transmit power allocations and different transmit antenna power distributions in its impairment correlation calculations. The receiver may be implemented in according to a variety of architectures, including, but not limited to, Successive Interference Cancellation (SIC) Generalized RAKE (G-RAKE), Joint Detection (JD) G-RAKE, and Minimum Mean Squared Error (MMSE) G-RAKE. Regardless of the particular receiver architecture adopted, the improved impairment correlations may be used to calculate improved (RAKE) signal combining weights and/or improve channel quality estimates for reporting by receivers operating in Wideband CDMA (W-CDMA) systems transmitting HSDPA channels via MIMO or MISO transmitters.

Abstract: A method for determining antenna weights for use in transmitting data from a plurality of base stations to a user device is disclosed. The antenna weights are determined using an input covariance matrix (S), and the input covariance matrix is determined subject to a predetermined power constraint and a predetermined, non-zero interference constraint.

Abstract: A radio communication sent by a transmitter having M transmit antennas is received by a receiver having N receive antennas, where M is a positive integer greater than or equal to one and N is positive integer greater than one. Thus, N output signals, one for each receive antenna, are received. The signal transmitted from each transmit antenna includes predetermined pilot symbols known by the receiver and information symbols to be determined by the receiver. Weights for estimating each of M×N single-input/single-output channels between transmit and receive antennas are determined based on jointly processing pilot symbols received on all of the N receive antennas. The M×N channels are estimated based on the determined weights, and those estimated channels are used to determine the information symbols. An iterative procedure is used to estimate the M×N channels using a noise correlation matrix estimate and to estimate the noise correlation matrix using the M×N channel estimates.

Abstract: A mobile phone is described herein that has control (or at least partial control) over which virtual antenna(s) in one or more base stations should be used for transmissions. In one embodiment, the mobile phone performs the following steps: (1) receives an antenna subset list (from the scheduling unit) which identifies a configuration of virtual antennas that is associated with the base station(s); (2) uses the antenna subset list to select which virtual antenna(s) in the configuration of virtual antennas should be used for transmissions; and (3) sends an antenna selection signal (to the scheduling unit) which contains information that instructs/requests the base station(s)/scheduling unit to use the selected virtual antenna(s) for transmissions.

Abstract: The required bitrate for reporting channel state information from a network transceiver to the network is dramatically reduced, while maintaining fidelity of channel estimates, by exploiting prior channel estimates and the time correlation of channel response. For a selected set of sub-carriers, the transceiver estimates channel frequency response from pilot signals. The transceiver also predicts the frequency response for each selected sub-carrier, by multiplying a state vector comprising prior frequency response estimate and a coefficient vector comprising linear predictive coefficients. The predicted frequency response is subtracted from the estimated frequency response, and the prediction error is quantized and transmitted to the network. The network maintains a corresponding state vector and predictive coefficient vector, and also predicts a frequency response for each selected sub-carrier.

Abstract: A wireless communication receiver improves signal impairment correlation estimation in MIMO/MISO systems by considering different transmit power allocations and different transmit antenna power distributions in its impairment correlation calculations. The receiver may be implemented in according to a variety of architectures, including, but not limited to, Successive Interference Cancellation (SIC) Generalized RAKE (G-RAKE), Joint Detection (JD) G-RAKE, and Minimum Mean Squared Error (MMSE) G-RAKE. Regardless of the particular receiver architecture adopted, the improved impairment correlations may be used to calculate improved (RAKE) signal combining weights and/or improve channel quality estimates for reporting by receivers operating in Wideband CDMA (W-CDMA) systems transmitting HSDPA channels via MIMO or MISO transmitters.

Abstract: According to one or more method and apparatus embodiments taught herein, network base stations reduce temporal variations in the interference perceived by mobile stations operating within the network by slowing down the rate at which they change or otherwise update the linear precoding settings applied to their transmitted Orthogonal Frequency Division Multiplex (OFDM) signals in comparison to the rate at which the base stations perform link adaptation. That is, the precoding-related component of measured interference (e.g., other-cell interference) at the mobile stations is made quasi-stationary with respect to channel quality reporting and link adaptation intervals by fixing the preceding settings used by each base station over time intervals substantially longer than the channel reporting/link adaptation intervals.

Abstract: In a wireless network, plural downlink signals from plural base stations are transmitted to a terminal. The plural downlink signals all carry the same information to the terminal. The terminal provides feedback on the downlink channels. The feedback provides information on the taps of the channels. The amount of information fed back is constrained. Based on the feedback, transmission parameters of the downlink signals are adjusted. The process of transmitting, providing feedback, and adjusting the parameters continue so that the energy of the downlink signal is enhanced at the terminal location and suppressed elsewhere. Beam forming can be used to further suppress the energy signature at locations other than the terminal location.