161results about How to "Improve channel estimation performance" patented technology

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.

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 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.

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.