System and method of timing recovery for recovering a clock signal by using adaptive channel response estimation. The channel response estimation in the timing recovery loop is dynamically adapted to the current channel response that varies over time. More particularly, the channel estimation coefficients used in a channel estimator can be adapted based on an error signal representing the difference between a received signal at the timing recovery loop and an estimated signal output from a channel estimator. Further, to prevent undesirable interaction between the channel estimator and the overall timing recovery loop with respect to clock phase recovery, the adaptation of channel estimation can be controlled in terms of speed or time so as to reduce or eliminate the channel estimator's effect on clock phase correction.

Methods and apparatuses are provided for performing a cell search by a receiver in a communication system. A scrambling code is identified by correlating a common pilot channel with a first synchronization accumulation length based on a frame boundary and a code group. A multipath signal is sought by correlating the common pilot channel with a second synchronization accumulation length based on the frame boundary and the code group. A difference between, or a ratio of, a first maximum value of first correlation values acquired during identification of the scrambling code and a second maximum value of second correlation values acquired during searching for the multipath signal, is determined. It is determined whether a frequency offset exists by comparing the difference or the ratio with a predetermined threshold value. The frequency offset is estimated and the frequency offset is transmitted to a demodulator, when the frequency offset exists.

The apparatus may be a UE configured to identify at least one performance metric associated with a channel estimation operation at the UE. The apparatus may further be configured to calculate at least one uncertainty value associated with the at least one performance metric. The apparatus may also be configured to transmit, to a network node, a first indication of the at least one uncertainty value associated with the at least one performance metric. The apparatus may be a network node, configured to receive, from a UE, the first indication and a second indication of at least one value for the at least one performance metric associated with the at least one uncertainty value and to select a set of parameters for a subsequent communication based on the at least one value for the at least one performance metric and the at least one uncertainty value.

Systems, methods, and devices to reduce the channel estimation overhead by collecting data from many UEs and building a location-based mathematical model are disclosed. During building of the model, a reference signal is used to collect location- and signal-related data from connected UEs. Once the model is successfully built, it is then transmitted and/or downloaded to each new UE that connects to the base station. The UEs and/or the base stations then use this model to determine their own transmission parameter values. The UEs also report their location to the base stations, which use the model to estimate channel conditions and adapt transmission parameters for themselves.

A base station apparatus includes at least one remote unit apparatus including at least one antenna; and a central unit apparatus connected to each remote unit via a transmission path. The remote antenna receives a wireless transmission signal from at least one wireless terminal including at least one antenna. The remote unit includes a channel estimation unit functioning between the terminal antenna and the remote antenna, using a reception signal received by the remote unit antenna; a reception signal processing unit that detects a reception signal corresponding to the transmission signal, using the channel information estimated by the channel estimation unit; a decoding unit that decodes each signal detected by the reception signal processing unit; and an inter-unit transmission unit that transmits each signal decoded by the decoding unit to the central unit. The central unit is provided with an inter-unit receiving unit and a signal selection unit.

The present invention discloses a channel estimation method, apparatus, and device and a multichannel microwave communications system. According to the channel estimation method, a first vector group corresponding to a transmit end and a second vector group corresponding to a receive end are first obtained according to a transmit-receive array size; then a subchannel estimation procedure is performed multiple times according to the transmit-receive array size, the first vector group, and the second vector group, to obtain multiple corresponding subchannel estimated coefficients; and finally, a real channel matrix is determined according to the first vector group, the second vector group, and an estimation matrix consisting of the multiple subchannel estimated coefficients.

Embodiments of the present disclosure provide a method and apparatus for determining a nonlinear characteristic and a system. The method for determining a nonlinear characteristic includes: determining a correction factor of a nonlinear item of a nonlinear model of a system to be measured according to an input and/or a parameter of the system to be measured; correcting the nonlinear item of a nonlinear model of the system to be measured by using the correction factor; and obtaining a nonlinear characteristic of the system to be measured according to the corrected nonlinear model. The nonlinear characteristic allows the input and/or the parameter of the system to be corrected to produce a corrected output. With the embodiments of the present disclosure, the nonlinear characteristic of the system to be measured under different inputs and/or parameters may be estimated, and accuracy of the estimation and applicability are improved.

Methods and systems for obtaining improved joint channel estimates for a multi-user, frequency-multiplexed data transmission such as SC-FDMA or OFDM begins by estimating separate contributions of users (and/or other signal sources) to the received signal based on joint frequency domain channel estimates. A reduced data set is obtained by subtracting contributions of one or more users from the received data, leaving only the estimated contributions of the remaining users, with noise and residual estimation error signal. Time domain joint channel estimation is then performed on the reduced data set, which is feasible because the number of users has been reduced. In exemplary embodiments, the reduced data set includes only one estimated user contribution. This process is repeated to obtain time domain estimates for all of the users. The method can be repeated by using the TD channel estimates to re-estimate the user contributions and calculate revised TD channel estimates.

Technologies and implementations for determining the location of a device in an indoor environment are generally disclosed.

A base station apparatus includes at least one remote unit apparatus including at least one antenna; and a central unit apparatus connected to each remote unit via a transmission path. The remote antenna receives a wireless transmission signal from at least one wireless terminal including at least one antenna. The remote unit includes a channel estimation unit functioning between the terminal antenna and the remote antenna, using a reception signal received by the remote unit antenna; a reception signal processing unit that detects a reception signal corresponding to the transmission signal, using the channel information estimated by the channel estimation unit; a decoding unit that decodes each signal detected by the reception signal processing unit; and an inter-unit transmission unit that transmits each signal decoded by the decoding unit to the central unit. The central unit is provided with an inter-unit receiving unit and a signal selection unit.