162results about How to "Improve channel estimation performance" patented technology

In the resource mapping method for data transmission, a time-frequency resource of a slot interval including OFDM symbols is divided into traffic channels and shared among the subscribers, the traffic channel including resource blocks uniformly distributed in the whole transmit frequency band, the resource block including consecutive subcarriers of consecutive received symbols having at least one inserted pilot symbol. The pilot symbols and the channel-encoded and modulated data symbols are processed by time-frequency mapping according to the resource-block-based mapping method to generate received symbols. The receiver separates the received symbols by subscribers according to the resource-block-based mapping method in a frequency domain, and performs iterative channel estimation, demodulation, and decoding by using the pilot and a data reference value after decoding for each traffic channel.

Pilot, preamble and midamble patterns are provided that are particularly suited for four transmit antenna OFDM systems. Pilots are inserted in a scattered manner for each of the four antennas, either uncoded, space-time coded in pairs, space-time frequency coded in pairs, or space-time-frequency coded.

The present invention relates to a method and system for transmitting a transmission signal from an antenna array (19) to a receiving means (20) of a wireless communication system, wherein a signal quality measurement is performed at the receiving means (20) for predetermined antennas or beams of said antenna array (19). Based on a feedback information derived from the signal quality measurement, at least two of the predetermined antennas or beams of the antenna array (19) are selected. The selected antennas or beams are used for transmitting said transmission signal according to a transmit diversity or beamforming scheme. Thus, spectral efficiency and diversity gain can be enhanced by using only selected ones of the predetermined antennas or beams.

In the resource mapping method for data transmission, a time-frequency resource of a slot interval including OFDM symbols is divided into traffic channels and shared among the subscribers, the traffic channel including resource blocks uniformly distributed in the whole transmit frequency band, the resource block including consecutive subcarriers of consecutive received symbols having at least one inserted pilot symbol. The pilot symbols and the channel-encoded and modulated data symbols are processed by time-frequency mapping according to the resource-block-based mapping method to generate received symbols. The receiver separates the received symbols by subscribers according to the resource-block-based mapping method in a frequency domain, and performs iterative channel estimation, demodulation, and decoding by using the pilot and a data reference value after decoding for each traffic channel.

A method and apparatus for providing information indicating radio resources for multi-cell interference measurement at a BS so that a UE can more accurately measure interference are disclosed.

A method for generating / transmitting a transmission-unit symbol sequence is disclosed. In the case of transmission information, the information is modulated in time and frequency domains on the basis of a predetermined transmission unit (e.g., a transmission time interval TTI or slot), simultaneous transmission of the information is made, and then a transmission unit symbol is generated / transmitted. A transmission sequence is masked in each symbol contained in one transmission unit. Symbol-unit circular shift (cyclic shift) is applied to the masked result, so that transmission efficiency increases. A control signal transmission method for supporting a variety of formats and a signal transmission method based on a prime-length sequence are also provided.

The present invention relates to a method and an apparatus for transmitting a reference signal by a base station in a wireless communication system. The base station generates a channel state information (CSI) reference signal (RS) for each of a plurality of layers, performs mapping the plurality of CSI-RSs to a resource element set constituted by a plurality of resource elements(REs) in a subframe and transmits the subframe with the plurality of mapped CSI-RSs. The plurality of resource elements constituting the resource element set are resource elements that are arranged with constant subcarrier spacing in two neighboring orthogonal frequency division multiplexing (OFDM) symbols, and the subframe has an extended cyclic prefix (CP) structure including 12 OFDM symbols.

A wireless communication system provides a method and device for transmitting a preamble. A transmitter generates a first preamble sequence used for frequency offset estimation and generates a second preamble sequence according to the transmission mode. The transmitter transmits the first and second preamble sequences. With respect to the second preamble sequence, the phase thereof may be shifted into different phase offsets according to the transmission mode.

A method and apparatus for transmitting Channel State Information Reference Symbol (CSI-RS) and data with partial muting of the CSI-RS are proposed. The method includes determining a CSI-RS pattern to be used among CSI-RS pattern candidates, determining a muting pattern for muting some resource elements constituting CSI-RS pattern candidates except for the determined CSI-RS pattern, mapping data symbols and CSI-RS to resource elements in a resource grid with rate patching in consideration of the CSI-RS pattern and muting pattern, and transmitting the data symbols and CSI-RS to a terminal.

A method and apparatus for pilot signal transmission is disclosed, which is capable of improving efficiency in a wireless communication system, the method comprising transmitting an uplink transmission frame for a first sector or cell by a mobile station through the use of basic pilot pattern in a resource block and transmitting an uplink transmission frame for a second sector or cell by the mobile station through the use of shift pilot pattern which is not overlapped with the basic pilot pattern in the resource block.

A method of transmitting a pilot method in a multi-antenna system is provided. The method comprises generating a preceding matrix including a preceding vector, the preceding vector being applied to each of data streams to be transmitted, performing preceding procedure for a pilot by using the preceding matrix, and transmitting the precoded pilot, wherein transmission power of the precoded pilot is determined specifically to the each of the data streams. The transmission power of a precoded pilot can be controlled adaptively, individually and independently for each channel to improve channel estimation performance.

In the ICI cancellation method for OFDM communication system, a receiver performs channel estimation using pilot subcarriers included in transmission signals transmitted from at least one transmitter. The transmitter generates the transmission signal in which pilot subcarriers and data subcarriers are regularly arranged, performs preceding on the transmission signal, modulates the pre-coded transmission signal into an OFDM symbol, and transmits the OFDM symbol. The receiver receives the OFDM symbol; demodulates the OFDM symbol, detects the pilot subcarriers from a demodulated signal, estimates channels using the pilot subcarriers, and restores the transmission signal using the estimated channels.

In the ICI cancellation method for OFDM communication system, a receiver performs channel estimation using pilot subcarriers included in transmission signals transmitted from at least one transmitter. The transmitter generates the transmission signal in which pilot subcarriers and data subcarriers are regularly arranged, performs preceding on the transmission signal, modulates the pre-coded transmission signal into an OFDM symbol, and transmits the OFDM symbol. The receiver receives the OFDM symbol; demodulates the OFDM symbol, detects the pilot subcarriers from a demodulated signal, estimates channels using the pilot subcarriers, and restores the transmission signal using the estimated channels.

The invention discloses an active user detection and channel estimation method with adaptive overhead. Using the estimated active user set and the channel thereof, the estimation quality is evaluatedby calculating the received signal error, and the time slot overhead of the pilot frequency in the frame structure can be adaptively adjusted according to the number of active users and the channel environment in the real system, so that the service quality is ensured with the access time delay as low as possible, and super-reliable active user detection and channel estimation are realized. The method also aims at an enhanced mobile broadband scene, large-scale machine type communication and other huge-address communication scenes in a cellular network in the future. According to the method, the pilot signal for broadband uplink unlicensed multiple access is reasonably designed by utilizing the sporadic characteristic of the uplink transmission flow of the user and the sparsity of a large-scale MIMO virtual angle domain channel, and an advanced compressed sensing technology is introduced, so that the access delay of the user can be greatly reduced.

The present invention provides a method for transmitting signals in a transmitter of a filter band multi-carrier system, comprising steps of: modulating data to obtain modulated data; obtaining a to-be-transmitted signal by framing a pilot preamble symbol with the modulated data; transmitting the to-be-transmitted signal; the pilot preamble symbol consisting of preamble elements, wherein the pilot preamble symbol corresponding to each transmit antenna occupies one filter band multi-carrier modulation symbol. The present invention further provides an apparatus for implementing the method, and a method and apparatus for channel estimation corresponding to the method for transmitting signals.

Disclosed is a radio communication device, and more particularly to a method for estimating a channel and compensating for error occurring in the estimation procedure, for a device for performing a frequency domain signal processing, such as Orthogonal Frequency Division Multiplexing (OFDM) The channel estimation method in a radio communication system includes the steps of: transforming a received OFDM signal into a frequency domain; estimating a channel frequency response (CFR) value from a result value obtained through the transformation by using a pilot signal; transforming the estimated CFR value into a time domain through an extended Inverse Fast Fourier Transform scheme, and detecting a channel impulse response (CIR) value; detecting a delay path position of a channel; modifying a non-ideal autocorrelation function; and compensating the estimated CIR value for error, through use of the detected delay path position and the non-ideal autocorrelation function.

Provided are a method and apparatus for transmitting reference signals in a wireless communication system. A first set of reference signals and a second set of reference signals are generated and mapped to a first resource block (RB) in accordance with a first reference signal pattern and a second RB which is close to the first RB in accordance with a second reference signal pattern. The first RB and the second RB are transmitted from a base station to user equipment. Each of the first reference signal pattern and the second reference signal pattern is formed of one sub-frame and on RB unit. In addition, resource elements (Rs) to which the first set of reference signals and the second set of reference signals are respectively mapped in accordance with the second reference signal pattern are REs to which the second set of reference signals and the first set of reference signals are respectively mapped in accordance with the first reference signal pattern.

Provided is a method of generating a pilot pattern capable of perform adaptive channel estimation, and a method and apparatus of a base station and a method and apparatus of a terminal using the pilot pattern. The pilot pattern selects pilot symbol positions based on distances from pilots of previous orthogonal frequency division multiple access (OFDMA) symbols to a subcarrier position of a current OFDMA symbol in the frequency domain and the time domain, so that a low pilot density is maintained so as to effectively transmit data, and stable channel estimation performance can be obtained even in a bad channel environment. In addition, the minimum burst allocation size is determined according to the channel environment between the base station and the terminal, guaranteeing channel estimation performance suitable for the channel environment, and improving granularity, channel estimation latency, and channel estimation memory size.

The present disclosure provides a communication method of mapping CSI-RS ports to antenna units arranged in an antenna array system, a base station, and a user equipment, the communication method comprises steps of: selecting a group of antenna units to map to the CSI-RS ports in a first CSI-RS transmission period or a first frequency resource region; and selecting another group of antenna units to map to the CSI-RS ports in a second CSI-RS transmission period or a second frequency resource region. By the method, base station, and user equipment according to the present disclosure, each antenna unit would get a relatively fair opportunity for transmitting the CSI-RS signals or get a fairly good channel estimation performance in UE side.

Disclosed are an apparatus and a method for generating a preamble signal for cell identification in an OFDM mobile communication system. The method includes the steps of generating a Walsh code symbol for a cell identification by combining Walsh codewords having a predetermined length and generating the preamble signal through multiplying the Walsh code symbol by a pseudo noise (PN) code having a length identical to a length of the Walsh code symbol.

The invention discloses a sparsity self-adaptive OFDM (Orthogonal Frequency Division Multiplexing) system channel estimation method and belongs to the technical field of mobile communication. The method comprises the following steps of 1, obtaining channel response at a pilot frequency, 2, establishing a channel model, 3, constructing an observation matrix and an observation value both needed by signal reconstruction, and 4, recovering channel impulse response according to a reconstructing algorithm. The method achieves the goal of high channel estimation performance even though a prior condition that the channel sparsity is known is not satisfied, and therefore, a simple and efficient solution is provided for sparse channel estimation; the method is capable of reducing the number of the pilot frequencies, improving the spectrum efficiency and effectively reducing the error of channel estimation.

A method for improving channel estimation performance in dynamic spectrum access multicarrier systems is disclosed. The method includes determining a pattern of pilot symbols to be included in transmitted signals sent from a sender to a receiver through an interference-affected propagation environment by deriving a covariance matrix of interference and white Gaussian noise (Rww) based on external measurements for the propagation environment, determining the placement of a predetermined number of equally powered pilot symbols by computing a placement that results in the minimum sum of square errors of a maximum likelihood channel estimation performed based on the covariance matrix, and with the pilot symbols in their placed positions, determining a relative power distribution between the placed pilot symbols by computing the power distribution that results in the minimum sum of square errors of a maximum likelihood channel estimation performed based on the covariance matrix.

The present invention relates to transmitting a downlink reference signal in a wireless communication system. A method for a base station to transmit a downlink signal by using two or more layers includes multiplexing and transmitting a reference signal for the two or more layers on the basis of a reference signal pattern on a data region of a downlink subframe and transmitting data for the two or more layers on the data region of the downlink subframe, wherein the reference signal for the two or more layers is a dedicated reference signal that is used to demodulate the data for the two or more layers on a receiving end, and in the multiplexing of the reference signal, the reference signal for the two or more layers is code-division-multiplexed by an orthogonal code having a length of at least 2.

The invention relates to the wireless communication field, and discloses a channel estimating method and the device thereof. The method can improve the channel estimating performance of the OFDM system without increasing the pilot frequency spending. The invention demodulates and decodes the data in virtual pilot channel, checks the decoded result, and reconstructs the decoded result as virtual pilot symbols and uses virtual pilot symbols and actual pilot symbols to estimate the channel when the decoded result passes through the check. All subcarriers forming the virtual pilot channel and allsubcarriers which are used for transmitting pilot symbols complement each other; for example, the two groups of subcarriers can be crosswise arranged at equal intervals.

In prior art, selection of precoding granularity is affected by two inter-restricting factors, i.e., precoding accuracy and channel estimation at a mobile terminal. To solve this problem, the present invention provides a method of maintaining coherency of a precoding channel in a communication network and an associated apparatus. During precoding, this method takes into account both channel coherency and system capacity. A base station adjusts phase and / or amplitude of a precoding matrix corresponding to each precoded unit to maintain coherency of associated information of the overall precoding channel. The associated information of the precoding channel includes, for example, CSI or eigenvalue matrix of the precoding channel. Afterwards, a mobile terminal performs channel estimation based on reference signals of multiple precoded units, thereby eliminating the limitation in prior art that a mobile terminal can perform channel estimation only within one or more resource block limited by a precoding granularity.

A reception apparatus including: a detection unit detecting extrinsic information based on an output of a tentative symbol decision unit, an output of a channel estimation unit, and an output of a noise variance estimation unit that are obtained from a previous iteration process; a Cyclic Redundancy Check (CRC) aided channel decoding unit outputting an encoded and interleaved bit, or a posteriori information thereof based on the extrinsic information; the tentative symbol decision unit determining a tentative transmission symbol based on an output of the CRC aided channel decoding unit; the channel estimation unit estimating a channel based on an output of the tentative symbol decision unit or a pilot symbol; and the noise variance estimation unit estimating a noise variance or an initial noise variance based on the output of the tentative symbol decision unit and the output of the channel estimation unit is provided.

The present invention discloses a method and an apparatus for processing data sending and a method and an apparatus for processing data receiving, wherein, the method for processing data sending includes: allocating the number of spatial transmission layers and a pilot resource for transmission at each spatial transmission layer; generating pilot resource information according to the number of spatial transmission layers and the pilot resource for transmission at each spatial transmission layer; and sending the pilot resource information to user equipment (UE). According to the embodiments of the present invention, the UE is enabled to determine a specific pilot resource to be used so as to effectively distinguish between user channels, obtain a correct channel estimation value, improve channel estimation performance, and thus, obtain correct service data.

An apparatus of transmitting a long training field includes: a station number determination unit configured to determine at least one station to be transmitted using transmission data or channel status information; a transmission stream allocation unit configured to determine the number of transmission streams for each of the least one station determined by the station number determination unit; a long training field number calculation unit configured to calculate the number of long training fields required for each of the at least one station determined by the transmission stream allocation unit and determines the least common multiple of the number of calculated long training fields of each station; and a long training field allocation unit configured to allocate the long training fields for each station to subcarriers allocated to each station to correspond to the least common multiple of the determined long training fields.

Disclosed is a pilot signal transmitting / receiving device and method in a wireless communication system. When generating a pilot signal block that is shorter than the length of a data signal, a frequency for each predetermined pilot signal block is transitioned so as to guarantee frequency domain channel estimation performance. A cyclic prefix according to the length of the transitioned pilot signal is added to the pilot signal, a data signal is time division multiplexed together with the pilot signal, and a resultant signal is transmitted through an antenna. In advance to this, a position of a subcarrier for transmitting the pilot signal and the data signal is determined, a data signal is mapped on the determined subcarrier, and in this instance, diversity on the channel for a symbol is used to map the data signal on the transmission method using one of the localized FDMA (L-FDMA) channel and the distributed FDMA (D-FDMA) channel. Therefore, the frequency resolution in the frequency domain is maintained to thus provide high-quality channel estimation performance.