A downlink channel estimation method based on a co-prime array in asymmetric massive MIMO architecture is provided. First, an uplink and downlink asymmetric receiving and transmitting system model based on a co-prime array is established, and a deviation of the frequency domain direction caused by array broadband signals is observed; then, uplink receiving is performed to estimate an uplink channel, and channel parameters such as the number of paths, the angle of arrival and the path gain are recovered; and finally, a downlink channel is reconstructed based on the channel parameters recovered according to the uplink channel. By means of the high angular resolution of the co-prime array, the problem that a recovered uplink channel cannot be directly used for pre-coding of a downlink channel is solved.

A method of estimating a channel for mobile systems with insufficient cyclic prefix length, wherein the channel comprises a plurality of multipath components (,), includes: receiving a signal (y.sub.n) comprising a plurality of contributions of a transmit signal (x.sub.n[k], x.sub.n-1[k]) transmitted during a plurality of transmission time intervals (n, n-1) on a plurality of sub-carriers of known pilots (kP.sub.b) and a plurality of sub-carriers of unknown data (k.Math.P.sub.b); determining an estimate of the plurality of multipath components (,) based on a probabilistic relation between the plurality of first contributions (x.sub.n[k], x.sub.n-1[k]) of the transmit signal, wherein the plurality of first contributions are transmitted during adjacent transmission time intervals (n, n-1), and an observation of the received signal (y.sub.n[k]) at a subcarrier (kP.sub.b) of the known pilots, wherein the probabilistic relation is based on statistical properties of the plurality of first contributions (x.sub.n[k], x.sub.n-1[k]) of the transmit signal.

Disclosed are a method and system for acquiring massive MIMO beam domain statistical channel information. A refined beam domain channel model involved in the disclosed method is based on a refined sampling steering vector matrix. Compared with a traditional DFT matrix-based beam domain channel model, when antenna size is limited, said model is closer to a physical channel model, and provides a model basis for solving the problem of the universality of massive MIMO for various typical mobile scenarios under a constraint on antenna size. The present invention provides a method for acquiring massive MIMO refined beam domain a priori statistical channel information and a posteriori statistical channel information, the a posteriori statistical channel information comprising mean and variance information of the a posteriori channel. The method of the present invention has low complexity, can be applied to an actual massive MIMO system, provides support for a robust precoding transmission method, and has large application value.

Methods, systems, and devices for wireless communication are described. A method may include receiving a control transmission from a base station, identifying a control channel search space organized according to a nested structure, the control channel search space including a plurality of control channel candidates associated with one or more control channel elements (CCEs) and an aggregation level, and searching the received control transmission to identify a control channel for the UE using the plurality of control channel candidates. Another method may include determining whether to reorder resource element group (REG) indices for a received control channel transmission based, at least in part, on a transmission mode associated with the control channel transmission. Another method may include decoding a received control channel transmission, where the downlink control information (DCI) formats may be constrained to an integer multiple of a predetermined base number of bits N.

The present disclosure relates to a method for estimating a channel in an uplink. A method for estimating a channel by a base station according to the present disclosure is characterized by comprising the steps of: continuously receiving at least one subframe; selecting the number of subframes to be used for channel estimation from the received subframes and extracting subframes based on the number of subframes; and performing channel estimation using reference signals in the extracted subframes.

The present invention adopts a configuration such that when cooperative reception by a plurality of base stations is not applied, a reference signal sequence determined from a selection baseline value corresponding to the number of a sequence group allocated to a cell belonging to the device in question is selected from among a plurality of selection baseline values as a reference signal sequence for non-cooperative reception, whereas when cooperative reception by a plurality of base stations is applied, a reference signal sequence determined from one or more intermediate selection baseline values set between two adjacent selection baseline values corresponding to the number of a sequence group allocated individually to a terminal device is selected among the plurality of selection baseline values as a reference signal sequence for cooperative reception differing from the reference signal sequence for non-cooperative reception.

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 channel estimates for all of the users. The method can be repeated by using the channel estimates to re-estimate the user contributions and calculate revised channel estimates.

Circuits for producing signals representative of mean and variance estimations for quadrature amplitude modulation (QAM) are provided where the circuits comprise: sequentially repeated first circuit modules and sequentially repeated second circuit modules configured for producing updates in the corresponding estimation iterations. In one embodiment, a closest negative integer power of 2 is used as a substitute multiplicand when multiplying together two or more outputs of hyperbolic function generating units where the substituted for output is less than one. Size and complexity of the corresponding multiplier can then be reduced.

A communication device includes: a receiving circuit, receiving a plurality of time-domain signals; a transforming circuit, coupled to the receiving circuit, transforming the plurality of time-domain signals to a plurality of frequency-domain signals according to a time-frequency transform operation; a magnitude circuit, coupled to the transforming circuit, performing an absolute value operation on the plurality of frequency-domain signals to generate a plurality of output signals; and a selecting circuit, coupled to the magnitude circuit, selecting a maximum signal that satisfies a check condition from the plurality of output signals.

A method performed by radio network node for enabling channel handling of a channel between a wireless device and the radio network node in a wireless communication network. The channel is defined in continuous time and a sampling rate of the channel is non-uniform. The radio network node predicts a channel gain using a first sampling descriptor indicating a first momentary sampling frequency and a second sampling descriptor indicating a second momentary sampling frequency, wherein the first sampling descriptor operates on a different segment of continuous time than the second sampling descriptor. The predicted channel gain enables channel handling such as channel estimation and link adaptation.