75results about How to "Improve Channel Estimation Accuracy" patented technology

Methods of improving channel estimation are described, in which pilot symbols are inserted into orthogonal frequency division multiplexing (OFDM) frames at an OFDM transmitter having at least one transmitting antenna, wherein for the or each antenna, historical data regarding channel conditions is obtained so that the scattered pilot symbols are inserted in a scattered pattern dependent upon said historical data. Alternatively, or in addition, an adaptive channel estimation filter is used whose parameters are selected according to analysis of historical data regarding channel conditions.

A base station that assigns frequencies to UP link pilot signals in a radio communication system, where the base station stores the correlation between each of a plurality of pilot sequences having different Peak to Average Power characteristics and a plurality of frequencies that are used for transmitting the pilot sequence by frequency multiplexing, and makes the correlation between each of said pilot sequences and said assigned frequencies in adjacent cells or sectors different. Moreover, the base station measures the reception quality of signals received from a user terminal, makes reference to the stored correlation and finds a pilot sequence having Peak to Average Power characteristic that correspond to said reception quality, then sends an instruction to the user terminal so that the user terminal transmits the pilot sequence using the frequencies assigned to this pilot sequence.

Provided is a cyclic shift sequence generation method which can prevent coming of an interference wave into a desired wave detection window even if a cyclic shift sequence has a high mutual correlation in different bandwidths, thereby improving a channel estimation accuracy in a base station. In this method, a cyclic shift sequence number to be allocated to a cell is decided in advance. Moreover, when the cyclic shift amount between cyclic shift sequences allocated in cells is Δ1 and the cyclic shift amount of the cyclic shift sequences allocated between the cells is Δ2, Δ1 and Δ2 are made different when generating a cyclic shift sequence.

Each of a general chunk to which pilot signals are allocated at a general density, and a high-density chunk to which pilot signals are allocated at a higher density than the density of the general chunk, is transmitted in a frequency band common to OFDM transmitters. Each of the OFDM transmitters allocates the high-density chunk to any one of OFDM receivers, which notifies poor receiving quality.

A method and system for improving channel estimation in a wireless device is disclosed. Aspects of the exemplary embodiment include receiving a data packet wirelessly transmitted from a transmitter, the packet including a preamble portion and a data portion containing data, wherein the preamble portion includes at least one training field and a second field; performing a first channel estimation using the training field; and using the second field to refine the first channel estimation.

A method and apparatus for filtering a received Orthogonal Frequency Division Multiplexed (OFDM) signal to reduce noise. The ODFM signal includes a plurality of symbols n in the time direction, each symbol including a plurality of sub-carriers k in the frequency direction, each a-th sub-carrier of each symbol being transmitted as a pilot sub-carrier with known amplitude and phase, and each symbol having its pilot sub-carriers spaced by b sub-carriers relative to the adjacent symbol. An m-tap filter is utilized for producing a filtered version of a selected pilot sub-carrier to be used in subsequent interpolation, by inputting into respective taps of the m-tap filter, m pilot sub-carriers surrounding the selected pilot sub-carrier. The m pilot sub-carriers each satisfy a relationship between n and k, wherein the relationship defines a diagonal line in the n-k plane.

A method for notifying a downlink demodulation pilot control signaling, includes: a base station side notifying a user equipment (UE) side of an index of a virtual signaling group and/or index of port offset signaling group used when generating a downlink pilot sequence and/or mapping the generated downlink pilot sequence through at least one of the following information: UE-specific or common high layer signaling; antenna indication information of DL_Grant; new data indication information in a Disable TB signaling in the DL_Grant; scrambling indication information in the DL_Grant; in a UE-specific or common search space, an aggregation level of the DL_Grant, a relative position of a first control channel element of the DL_Grant in the UE-specific or common search space, a subframe number where the DL_Grant is located and a system frame number where the DL_Grant is located.

Provided is a method for performing channel estimation in an Orthogonal Frequency Division Multiplexed (OFDM) signal. The method includes performing the channel estimation based upon use of reserved tone channel carriers.

The invention provides a small-scale fading channel estimation method orientated to a large-scale array antenna MIMO communication system. In the method, firstly, large-scale fading estimation values from user terminals of all adjacent regions to a target cell base station are sorted from small to large, and strong interference users of the adjacent regions are selected according to channel estimation residue processing ability of the target cell base station; on the basis, a multi-cell large-scale fading matrix and a multi-cell system matrix are built, joint channel estimation is conducted on pilot frequency receiving signals separated from the base station according to the MMSE criterion, and therefore high-accuracy estimation of an ascending small-scale fading channel from a target cell user to the target cell base station is obtained. In addition, periodic random allocation is conducted on user ascending pilot frequency sequences according to the interference randomization principle, and adjacent region interference caused by cross-correlation difference among the pilot frequency sequences is reduced. The small-scale fading channel estimation method can effectively increase accuracy of small-scale fading channel estimation of the large-scale MIMO system.

Disclosed in the present invention is a pre-coding method for hybrid multiplexing demodulation reference symbol (DMRS). The method includes: determining a multiplexing relationship between DMRS ports; making layers of data transport correspond to DMRS ports with the multiplexing relationship determined; and pre-coding pilot sequences corresponding to various DMRS ports according to the relationship between the layers of data transport and the DMRS ports. Also disclosed in the present invention is a method for mapping from a layer to a multiplexing demodulation reference symbol (DMRS) and an apparatus for achieving pre-coding based on a hybrid multiplexing demodulation reference symbol (DMRS). By way of the technical solution of the present invention, interference between the layers corresponding to different codeword streams can be avoided, and the accuracy of channel estimation can be improved.

Provided is a radio communication device which can separate propagation paths of antenna ports and improve a channel estimation accuracy even when using virtual antennas. The device includes: a mapping unit (103) which maps a data signal after modulation to a virtual antenna (0) and a virtual antenna (1); a phase inversion unit (104) which inverts the phase of S0 transmitted from an antenna port (2) in synchronization with a phase inversion unit (105) between the odd-number slot and the even-number slot; the phase inversion unit (105) which inverts the phase of R0 transmitted from the antenna port (2); a phase inversion unit (113) which inverts the phase of S1 transmitted from an antenna port (3) in synchronization with a phase inversion unit (114); and the phase inversion unit (114) which inverts the phase of R1 transmitted from an antenna port (3).

The present invention provides a channel estimation apparatus in which channel estimation may be made higher than heretofore in accuracy and may be used for calculating the weight for an equalization filter to achieve an optimum equalizing performance. A subcarrier copying unit 20 copies K items of end-side subcarriers, using the channel estimation obtained by a correlation processing unit 14 and K which is a subcarrier copy number. An IDFT unit 15 transforms the channel estimation obtained at the subcarrier copying unit 20 into the time domain channel response. A noise path removing unit 16 removes noise paths from the channel response output from the IDFT unit 15. A DFT unit 17 performs DFT of the channel response, from which the noise paths are removed by the noise path removing unit 16, to output a noise-suppressed frequency domain channel estimation value. A weight calculation unit 5 inputs the frequency domain channel estimation value output from the DFT unit 17 to calculate an equalizing weight.

A channel equalizer obtains channel impulse responses (CIRs) for all subcarriers by way of filtering channel impulse responses of specific subcarriers using at least two filters. One of the two filters may be a low pass filter. At least one other of the at least two filters is implemented as a band pass filter having a variable filtering bandwidth, being available to establish various filtering bandwidths in response to various multi-path channel environments. By improving the performance of channel estimation, equalization may be improved.

The invention belongs to the technical field of information and communication, and relates to a semi-blind channel estimation method suitable for a large-scale MIMO system assisted by an intelligent reflecting surface. In order to reduce the pilot overhead of a sending end and improve the channel estimation precision, the invention provides a semi-blind channel estimation method for Bayesian approximate message passing by solving the problem of trilinear matrix decomposition, i.e., only part of sequences in sending symbols are used as pilot symbols. According to the method disclosed by the invention, the maximum calculation overhead of each iteration is only the product operation of the matrix and the vector, the calculation complexity and expandability are relatively low, relatively accurate channel estimation can be obtained under the condition of a small number of pilot frequencies, and meanwhile, unknown symbol sequences of a part of sending ends are detected.

Provided are a method and device for estimating a channel in a wireless communication system, and more particularly, a method of estimating a channel of an uplink signal in an orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) communication system supporting the Institute of Electrical and Electronics Engineers (IEEE) 802.16d/e standards and a channel estimation device employing the method. The method includes the steps of: extracting pilot symbols included in the received signal and estimating linear phase values using the pilot symbols; interpolating the pilot symbols along a time axis and obtaining first channel responses; interpolating the pilot symbols along a frequency axis according to the first channel responses and obtaining second channel responses; and calculating channel estimation values using the second channel responses and the linear phase values.

A channel estimation apparatus with the optimal search and the method thereof are disclosed. The channel estimation apparatus includes a time-domain-axis channel estimation unit, a peak-detection module, a first-shift unit, a frequency-domain-axis channel estimation unit and a shift-optimal-searching module. The time-domain-axis channel estimation unit is used for performing the channel estimation in the time domain so as to obtain initiative channel frequency responses by estimating. The peak-detection module is used for outputting a peak information. The shift-optimal-searching module decides the optimal shift information according to the peak information, a feedback signal and entire channel frequency responses. The first-shift unit is used for adjusting the positions of the initiative channel frequency responses in the time domain according to the optimal shift information. The frequency-domain-axis channel estimation unit is used for performing the channel estimation in the frequency domain so as to obtain the entire channel frequency responses by estimating.

The invention belongs to the wireless communication Internet of vehicles technology field and particularly relates to a demodulation reference signal mode setting method for an LTE-V2X system. According to a frame structure set based on the method, the DMRS interval in the frequency domain direction is 6, and the DMRS interval in the time direction is 1; or the DMRS interval in the frequency domain direction is 6 or 3, the SC-FDM symbol position in the time direction is divided into two portions, including the front portion and the back portion, DMRS are distributed from the initial portions of the front portion and the back portion, and the DMRS interval of each portion is 2. The method is advantaged in that three types of LTE-V2X system demodulation reference signal design modes are proposed, density of demodulation reference signals in the time domain direction is enhanced, relatively high Doppler of a V2X system can be better responded, moreover, the intervals of the demodulation reference signals in the frequency domain direction are enhanced, confrontation to the relatively large time delay is further guaranteed, cost of the DMRS can be reduced to the maximum degree, and thefrequency spectrum utilization rate is improved.

A transmission method of a wireless signal including the following steps is provided. Multiple orthogonal frequency division multiplexing (OFDM) symbols carried by multiple subcarriers are generated according to a data signal. A scrambling pattern including multiple scrambling symbols is generated, wherein the scrambling symbols respectively correspond to the subcarriers in the frequency domain. The scrambling symbols corresponding to two contiguous subcarriers are correlated. The scrambling symbols are utilized to encode the OFDM symbols carried by the corresponding subcarriers.

Disclosed is a transmission device including a plurality of antennas for transmitting signals in the same channel at the same time point to a plurality of reception devices, characterized by including: a DRS generator configured to generate DRSs (dedicated reference signals) for the respective reception devices; a nonlinear spatial multiplexer configured to generate a nonorthogonal DRS by use of a first group of DRSs including at least one of the DRSs; and a transmitter configured to transmit a signal containing at least the nonorthogonal DRS.

The invention discloses a channel estimation method under a high-speed mobile environment, and is characterized in that a channel estimation method based on a base extension model is utilized to obtain channel estimation values at pilot frequency character positions; then optimal time-domain interpolation coefficients at the pilot frequency character positions corresponding to the channel estimation method based on the base extension model are calculated; and finally the obtained channel estimation values at the pilot frequency character positions multiplies the obtained optimal time-domain interpolation coefficients to obtain channel estimation values at data character positions. In the method, the exact channel estimation values at the pilot frequency character positions are combined with the optimal time-domain interpolation coefficients by the calculation so as to exactly estimate the channel estimation values at the data character position under the high-speed mobile environment,thus the channel estimation accuracy is obviously improved by using the channel estimation method provided by the invention under the high-speed mobile environment compared with an existing channel estimation method. The channel estimation method provided by the invention is applied to carrying out the channel estimation on wireless mobile communication systems using starlike pilot frequency patterns or block pilot frequency patterns frame signals under the high-speed mobile environment.

The invention provides a channel estimation method of an MIMO OFDM system, and the channel estimation method comprises the following steps: step one, a received signal is synchronized, and a time-domain signal after the synchronization is generated; step two, discrete Hartley transformation is carried out on the time-domain signal, and a Hartley-domain signal is output; step three, a real number orthogonal matrix is constructed by utilizing the mapping relationship between discrete Fourier transformation and the discrete Hartley transformation; step four, the time-domain channel shock response is estimated through the transpose of the constructed real number orthogonal matrix and the output Hartley-domain signal. The invention further provides a method for interpolating pilot frequency points based on the discrete Hartley transformation. The contradiction which exists between the estimation precision and the realization complexity of the existing channel estimation method of the MIMO OFDM communication system can be overcome through the invention.

The invention belongs to the technical field of mobile communication and provides a channel estimation method based on a time-domain sliding window. The method includes the following steps: according to reference signal sign frequency domain estimation values in the time-domain sliding window, calculating time-domain estimation coefficients corresponding to subcarriers on OFDM symbol positions; according to the reference signal symbol frequency domain estimation values and the time-domain estimation coefficients, performing time-domain channel estimation on OFDM symbols without reference signals and outputting a channel estimation value; and updating the reference signal symbol frequency domain estimation values in the sliding window. The invention also provides a channel estimation device based on the time-domain sliding window. The device is capable of obtaining a higher channel estimation precision compared with a linear interpolation estimation technology based on two reference signals; the time-domain sliding window is adopted and in terms of time, channel information in the history or at a present moment is mainly used and a repeated or mixed output mode is adopted so that the estimation performance is improved and at the same time, larger processing waiting or realization difficulties are not brought; and the real-time update of the sliding window ensures self-adaption to a time-varying channel in an estimation process.

The invention provides a large-scale MIMO channel estimation method and system. The large-scale MIMO channel estimation system consists of a base station and at least one user; and a linear signal processing technology is utilized, properties of a channel and related noise statistic characteristics are not changed, and complex correlation analysis of data, noise and the channel is converted into a common calculation problem, so that when consumption of pilot frequency resources is not increased, channel estimation accuracy is obviously promoted.