76results 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.

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.

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.

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.

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.

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 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.