92results about How to "Improved channel estimation" patented technology

The evolution of high rate data services within future wireless networks will call for new RF access technologies to enable substantial increases in overall system spectral efficiency at an acceptably low cost to the user. Space-Time Coding (STC) is an antenna array processing technology currently simulating considerable Interest across the wireless industry. The invention provides a space-time coding apparatus having an input, a trellis encoder, a modulator, a demultiplexer, and a set of signal outputs wherein the input is operable to receive a stream of data. This allows de-multiplexing to take place after coding and modulation has been performed. The trellis encoder comprises a convolutional encoder operable to sequentially group data to provide coded bits to provide QPSK symbols. By the selection of convolutional encoder rates and / or modulation alphabets STCs of any desired dimensionality may be produced including multi-dimensional codes.

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 technique for performing channel tracking and / or channel estimation in a wireless communication device includes receiving a reference signal and one or more non-error propagation physical channel signals. In general, the one or more non-error propagation physical channel signals must be correctly decoded before a data channel can be decoded. Channel tracking and / or channel estimation are / is then performed based on the reference signal and at least one of the one or more non-error propagation physical channel signals.

The present invention relates to improved multiple access communications. In one form, the invention relates to an improved signal processing method and apparatus for an iterative method of determining the reception of a signal in a multi user packet based wireless OFDM (Orthogonal Frequency Division Multiplexing) communication system. In other forms the present invention provides recursive filtering for joint iterative decoding in a variety of systems and functions such as linear multiple access channel decoders, iterative equalisation, iterative joint channel estimation and detection / decoding, iterative space-time processing, iterative multi user interference cancellation and iterative demodulation. In one particular form the present invention provides an iterative decoding circuit for a wireless multiuser communications receiver comprising a first signal processing means for receiving at least one received signal, said first signal processing means comprising at least two linear iterative filters such that the first linear iterative filter provides an estimate of a selected received signal to an estimated signal output and a second linear iterative filter provides estimates of at least one other received signal, delayed by one iteration cycle, to an input of said first linear iterative filter, a second signal processing means for receiving the estimated signal output of the first linear iterative filter and providing a further received signal estimate to the input of the first signal processing means in a succeeding iteration cycle of the decoding circuit.

A communication system comprises a downlink data channel for the transmission of data packets from a primary station to a secondary station and two uplink control channels, a first channel for transmission of status signals to indicate the status of received data packets and a second channel for transmission of pilot information. In operation, on detection (402) of a data packet the secondary station increases (404) the transmission power of the second channel, thereby enabling the primary station to obtain a better estimate of uplink channel properties and hence increase the accuracy with which it can decode the status signal. The secondary station transmits (406) the status signal, typically either an acknowledgement (ACK) or negative acknowledgement (NACK), and decreases (408) the transmission power of the second control channel signal. The increase and decrease in power are not necessarily identical, for example as a result of the effects of power control.

The present invention relates to improved multiple access communications. In one form, the invention relates to an improved signal processing method and apparatus for an iterative method of determining the reception of a signal in a multi user packet based wireless OFDM (Orthogonal Frequency Division Multiplexing) communication system. In other forms the present invention provides recursive filtering for joint iterative decoding in a variety of systems and functions such as linear multiple access channel decoders, iterative equalisation, iterative joint channel estimation and detection / decoding, iterative space-time processing, iterative multi user interference cancellation and iterative demodulation. In one particular form the present invention provides an iterative decoding circuit for a wireless multiuser communications receiver comprising a first signal processing means for receiving at least one received signal, said first signal processing means comprising at least two linear iterative filters such that the first linear iterative filter provides an estimate of a selected received signal to an estimated signal output and a second linear iterative filter provides estimates of at least one other received signal, delayed by one iteration cycle, to an input of said first linear iterative filter, a second signal processing means for receiving the estimated signal output of the first linear iterative filter and providing a further received signal estimate to the input of the first signal processing means in a succeeding iteration cycle of the decoding circuit.

A small cell communication system and an operating method thereof are provided. The small cell communication system comprises a base station and a mobile device. The base station is configured to determine a reference signal pattern from a plurality of reference signal patterns, determine a physical resource block (PRB) bundling size corresponding to the reference signal pattern and transmit a signal with the PRB bundling size and the reference signal pattern. The mobile device is configured to receive the signal and perform channel estimation according to the PRB bundling size and the reference signal pattern. The operating method is applied to the small cell communication system to implement the aforesaid operations.

A method and apparatus are provided for transmitting and receiving pilot signals to estimate link gains and channels of neighboring base stations in an orthogonal frequency division multiple access (OFDMA) system. Each base station cyclically shifts a frequency domain signal of the same pseudo random (PN) code by a predetermined multiple of a time interval between pilots. A mobile terminal cyclically shifts a time domain pilot signal by a time interval between pilots associated with a base station with which the mobile terminal currently communicates in a reverse direction of cyclic shift of the base station, and estimates a channel and a link gain of the base station.

A method and system for improving frame synchronization, channel estimation and access in a wireless network are disclosed. As one example, a method for improving frame synchronization and channel estimation in a wireless network is disclosed. The method includes the steps of generating a first preamble for a frame, generating a false control message for the frame, and scheduling a quiet interval for the frame.

A method of estimating a channel length (304) in a wireless receiver is disclosed. The receiver receives a signal (122) from a remote transmitter. The receiver selects a plurality (K) of different candidate channel lengths and determines a respective criterion value (402) of the signal for each of the plurality of different candidate channel lengths. The receiver selects a channel length (410) from the plurality of different candidate channel lengths in response to the respective criterion value (404).

A receiver for use in a pilot-aided OFDM system and a method of performing channel length estimation of a channel in a wireless communication system includes using transmitted and received wireless signals to estimate a channel carrier function vector at continuous and scattered pilot positions of consecutive OFDM symbols; performing time-domain interpolation by (i) upsampling the estimated the channel carrier function vectors at the scattered pilot positions by inserting zeros in between estimated scattered pilot positions, and (ii) filtering the upsampled vectors using a finite impulse response filter comprising a filter bank comprising a plurality of filters; mapping the channel carrier function vector to only one of the filters in the filter bank located in the finite impulse response filter, wherein the mapping causes noise reduction and enhanced channel estimation thereby increasing a maximum Doppler frequency in the channel.

A method for improving the performance of OFDM (Orthogonal Frequency Division Multiplexing) systems addresses the channel estimation, equalization and decoding problems of conventional techniques and provides improved performance in a wide range of operating conditions that include varying Signal to Noise Ratio (SNR) levels, data rates, and fading channels. The method teaches SNR based selection in the use / choice of a smoothing filter. The invention further teaches using a smoothing filter in combination with Decision Feedback Equalization (DFE), using a smoothing filter in combination with WCSI (Weighted Channel State Information) decoding, which may be combined with DFE, and data rate based selection ( for example, in IEEE 802.11 a / g applications) in employing a decision feedback based correction.

A communication method and device operates in a network in which a multiplicity of communication devices communicate over a shared communication channel. The communication device includes a transmitter that transmits to a second communication device over the shared communication channel a first packet P1, employing a starting tone map TMS that includes a starting transmission scheme for a set of carriers of said channel, a receiver that receives over the shared channel a partial tone map PTM1 from the second communication device, and a tone map generator that generates an updated tone map TM1 based on the starting tone map TMS modified in accordance with the partial tone map PTM1. The transmitter transmits over the shared channel a second packet P2 to the second communication device, employing the updated tone map TM1. The partial tone map may be received as part of an acknowledgment packet from the second communication device.

A method and system are directed to enabling a detector to perform relatively accurate channel estimates on blocks of data that include relatively short training sequences in wireless communication signals. Channel re-estimation is performed by transferring the estimation calculations from the time domain into a channel state domain. In one embodiment, information obtained from known training sequences and unknown data may be combined to generate an initial channel estimate. An embodiment of a new recursive Expectation Maximization (EM) process generally i) initializes the EM process with the initial channel estimate; ii) determines updates for the channel estimates; iii) produces a reduced observation vector; iv) generates a special sequence of channel states; v) rearranges each channel state estimate in the reduced observation vector; vi) generates a low-dimensional channel model matrix inversion based on the generated special sequence of channel states; and vii) generates channel estimates based on the generated matrix inversion.

Methods, systems, and devices for wireless communication are described. One method includes identifying a plurality of intermediate precoders corresponding to a plurality of tone subsets. The plurality of intermediate precoders define a plurality of vectors across the plurality of tone subsets. The method further includes selecting, for each vector of the plurality of vectors, a subset of non-frequency domain components of the vector, such as time-domain components; modifying the plurality of intermediate precoders to a plurality of smoothed precoders based at least in part on the selected subset of non-frequency domain components for each vector; and precoding a plurality of transmit streams using the plurality of smoothed precoders. The plurality of smoothed precoders is smoothed in a frequency domain compared to the plurality of intermediate precoders. Smoothing precoders may enable application of wideband channel estimation techniques using user equipment (UE)-specific reference signals.

The present invention discloses a method for determining an uplink demodulation reference signal (DMRS), which includes: taking one of multiple transmit antennas in the uplink as a base transmit antenna, taking other transmit antennas as subordinating transmit antennas and setting a DMRS for the base transmit antenna; establishing DMRS subordinating relationships between the base transmit antenna and each of the subordinating transmit antennas; and setting a DMRS for each of the subordinating transmit antennas according to the DMRS of the base transmit antenna and the DMRS subordinating relationship between the base transmit antenna and each of the subordinating transmit antennas. The present invention also provides a user equipment (UE) and an uplink system for providing DMRSs for multiple transmit antennas. The method, UE and system are applicable in both SU-MIMO transmission and MU-MIMO transmission.

The invention relates to a time division duplex transmission method for a broadband wireless communication system, belonging to the technical field of digital information transmission. The method comprises the following steps: using a time / frequency-domain unified orthogonal frequency division multiple access (TFU-OFDMA) technology to carry out downlink multiple access so as to obtain downlink signals at a transmitting end of a base station; using a time / frequency-domain unified single carrier multiple access (TFU-SCMA) technology to carry out uplink multiple access so as to obtain uplink signals at a transmitting end of user equipment; and using a time division duplex frame structure to carry out duplex transmission on the downlink signals and the uplink signals. The TFU-OFDMA technology provided by the invention solves the multiple access problems in the TFU-OFDM (Time / Frequency-domain Unified Orthogonal Frequency Division Multiplexing) modulation process, can flexibly allocate wireless resources and can effectively overcome deep fade, narrow-band interference and the like. The TFU-SCMA technology provided by the invention solves the multiple access problems in the improved SC-FDE (Single Carrier Frequency Domain Equalization) modulation process, reserves the advantages of low complexity of the transmitting end in the SC-FDE technology, low peak-to-average power ratio and the like, and enables the receiving end to be subject to synchronization and channel estimation better.

An apparatus and method for transmitting a message in a mobile communication system are provided, in which a short message is generated to be sent together with a preamble signal on the RACH, for uplink transmission, the short message and the preamble signal are spread with different orthogonal spreading codes, the phase of the short message is rotated to be orthogonal to the phase of the preamble signal, the phase-rotated short message is added to the preamble signal, and the sum is sent.

Aspects of the present disclosure provide for enhanced channel estimation in a wireless communication network. Uplink channel estimation may be enhanced by increasing the uplink transmit power of an uplink reference signal. For example, the uplink transmit power may be increased by multiplying a measured downlink path loss by a predetermined factor to produce an increased downlink path loss and calculating the uplink transmit power based on the increased downlink path loss. Downlink channel estimation may be enhanced by increasing a number of tones on a downlink reference signal assigned to a scheduled entity relative to the number of tones assigned to other scheduled entities.

The invention provides a feedback-type channel estimation method and device based on a PN sequence and a pilot frequency in an OFDM system, said method obtains an impulse channel estimation of this OFDM symbol by obtaining a channel impulse response of a pseudo-random (PN) sequence of a received signal; then by obtaining a channel estimation of the pilot frequency symbol; and then by combining the former two results with a channel estimation of a previous OFDM symbol. The new channel estimation method of this invention can complete the interpolation function It has the advantages of high performances and low complexity, and is particular useful for OFDM system in high speed and long delay multi-path environment.

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 provides a feedback-type channel estimation method and device based on a PN sequence and a pilot frequency in an OFDM system, said method obtains an impulse channel estimation of this OFDM symbol by obtaining a channel impulse response of a pseudo-random (PN) sequence of a received signal; then by obtaining a channel estimation of the pilot frequency symbol; and then by combining the former two results with a channel estimation of a previous OFDM symbol. The new channel estimation method of this invention can complete the interpolation function It has the advantages of high performances and low complexity, and is particular useful for OFDM system in high speed and long delay multi-path environment.

An adaptive frequency equalization system providing an equalizer that has programmable taps that adjusts magnitude and phase of symbol information of a received signal and that provides equalized symbol information. The system includes a hard decision circuit that selects ideal symbol values using the equalized symbol information. A frequency response circuit determines frequency response update values using the ideal symbol values and the received signal. An adjust circuit updates stored frequency response information using the frequency response update values, and also updates the programmable taps of the equalizer using the stored frequency response information.

Equipment for transmitting a signal, the equipment comprising an antenna array (600-606) for providing three or more radiation antenna patterns. The equipment is arranged to transmit a primary common pilot signal with at most two radiation patterns and a secondary common pilot signal with at least one radiation pattern. The equipment comprises controllers (622a-622d) for adjusting the power ratio between the primary and the secondary common pilot signal and the total power of the primary and the secondary common pilot signals, and controllers (614a-614d) for adjusting the transmit power of the dedicated pilot signal, such that the power levels of the dedicated pilot signals transmitted with the same radiation patterns as the secondary common pilot signal are relatively higher than the power levels of the dedicated pilot signals transmitted with the same radiation patterns as the primary common pilots.

Methods and apparatus for performing spectral filtering of channel estimates corresponding to a communications channel used to transmit a multi-tone signal are described. A channel estimate is examined to identify portions where significant multi-path interference is present. Real, as opposed to complex, low pass filters are used to perform spectral filtering on the channel estimate to produce a filtered channel estimate. Values corresponding to portions of the channel estimate determined to correspond to areas where significant multi-path interference is present are replaced with the original unfiltered channel estimate values to generate a selectively filtered channel estimate. By using unfiltered channel estimate values in areas of multi-path interference, the errors introduced in such areas by real filtering are avoided without the need to resort to complex filtering.

Synchronization and signal channel estimation is accomplished by adding pilot signals to the outputs of IFFT encoders, i.e. after encoding of data / symbols, in a spread spectrum wireless communication system utilizing uniquely designed OFDM transmitters, OFDM receivers and OFDM systems and methods.

The invention provides a time-varying OFDM system channel estimation method based on deep learning. The system randomly generates a sending data signal bit stream; forming a sending frame with a training symbol; carrying out binary phase shift keying modulation; performing inverse fast Fourier transform; adding a cyclic prefix to overcome inter-symbol interference, carrying out serial-to-parallelconversion, obtaining a received signal through a fast time-varying OFDM channel and noise addition, constructing and training a CPR-Net model, generating more accurate Doppler frequency shift, and after channel reconstruction response is carried out, recovering a received signal bit stream through signal detection. According to the invention, the deep learning method is introduced into the fast time-varying OFDM system, and the channel estimation and signal detection performance in the fast time-varying OFDM system is improved by using the deep neural network, so that the channel parameter estimation precision and the overall bit error rate performance of the system are improved.

The application provides a method for sending a reference signal and a device for sending a signal. The method for sending the reference signal includes the following steps: generating a first reference signal according to a data signal, an interference relationship between adjacent carrier waves, and a predefined second reference signal; modulating and sending the data signal and the first reference signal on corresponding carrier by utilization of a non-orthogonal multi-carrier modulation waveform. The application also discloses a method for receiving the reference signal and a device for receiving the signal. According to the application, the utilization rate of carrier resources can be improved, and the interference on the reference signal can be reduced, so that the better channel estimation and synchronization performance can be provided.

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.