6339 results about "Channel state information" patented technology

Channel state information (CSI) can be used by a communications system to precondition transmissions between transmitter units and receiver units. In one aspect of the invention, disjoint sub-channel sets are assigned to transmit antennas located at a transmitter unit. Pilot symbols are generated and transmitted on a subset of the disjoint sub-channels. Upon receipt of the transmitted pilot symbols, the receiver units determine the CSI for the disjoint sub-channels that carried pilot symbols. These CSI values are reported to the transmitter unit, which will use these CSI values to generate CSI estimates for the disjoint sub-channels that did not carry pilot symbols. The amount of information necessary to report CSI on the reverse link can be further minimized through compression techniques and resource allocation techniques.

A method of decoding a channel state information reference signal (CSI-RS) is presented. An indication of a resource element (RE) configuration allocated for transmission of CSI-RSs by a first cell is received from a second cell. The method includes at least one of using the indication of the RE configuration to decode a first CSI-RS received from the first cell, and using the indication of the RE configuration to mute one or more REs within a data channel transmission received from a third cell. The first cell, second cell and third cell may be associated within a CSI-RS group. In some cases, at least two of the first cell, the second cell, and the third cell are mutually interfering cells. The indication of the RE configuration may include a plurality of logical indices having incremental values, the plurality of logical indices identifying REs used to transmit CSI-RS.

Systems and methods of optimizing communication channels in multi-user communication systems are provided. Coding weights are determined based on communication channel state information for communication channels between a transmitter and multiple receivers. The coding weights are applied to communication signals to be transmitted from the transmitter to the receivers. Each receiver decodes received signals using inverses of the coding weights. Embodiments of the invention support multi-user MIMO (Multiple Input Multiple Output) where each receiver has fewer antennas than the transmitter, and enhance system performance if the total number of antennas at all of the receivers exceeds the number of antennas at the transmitter.

A system and method are described for powering a vehicle using radio frequency (“RF”) signals. For example, a method according to one embodiment of the invention comprises: positioning an antenna array beneath or on the road surface of a roadway, the antenna array configured to transmit RF signals responsive to RF processing logic and/or circuitry; coupling a rectenna array to a vehicle, the rectenna array configured to receive the RF signals transmitted from the antenna array and to generate power from the RF signals; providing feedback signals from the vehicle to the RF processing logic and/or circuitry, the feedback signals including channel state information (CSI) defining a current state of the channels between the antenna array and the rectenna array, the RF processing logic and/or circuitry using the channel state information to adjust the RF signal transmissions from the antenna array to improve the efficiency of the power generated by the rectenna array; and using the power generated by the rectenna array to power the vehicle.

A wireless communication includes a base station that configures a set of non-zero power reference signals corresponding to multiple potential transmission points to one or more users equipment UEs and configures at least one zero-power reference signal, with zero transmission power from one or more of the multiple transmission points. The base station transmits configuration information to at least one UE of the one more UEs, wherein the configuration information corresponds to a set of resource elements that are associated with a set of channel state information reference signals and wherein the set of channel state information reference signals include the set of nonzero-power reference signals and the at least one zero-power reference signal. The UE then performs a channel measurement based on one or more non-zero-power reference signals of the set of non-zero-power reference signals and performs an interference measurement based on the at least one zero-power reference signal.

Methods and systems are disclosed for determining sensor degradation by actively controlling an autonomous vehicle. Determining sensor degradation may include obtaining sensor readings from a sensor of an autonomous vehicle, and determining baseline state information from the obtained sensor readings. A movement characteristic of the autonomous vehicle, such as speed or position, may then be changed. The sensor may then obtain additional sensor readings, and second state information may be determined from these additional sensor readings. Expected state information may be determined from the baseline state information and the change in the movement characteristic of the autonomous vehicle. A comparison of the expected state information and the second state information may then be performed. Based on this comparison, a determination may be made as to whether the sensor has degraded.

An apparatus and method to dynamically schedule user devices in a wireless communication system in single-user multiple-input multiple-output (SU-MIMO) or multiple-user multiple-input multiple-output (MU-MIMO) modes of operation. The dynamic scheduling employs an efficient differential reporting of channel state information that reduces uplink feedback overhead, whereby a base layer value of a channel quality indicator (CQI) is reported in conjunction with a CQI offset value. Antenna subset selection is also reported. The offset value reflects gains by detection with successive interference cancellation if multiple antennas are reported (rank>1), while it reflects the actual offset between single-layer SU-MIMO CQI and MU-MIMO CQI if a single antenna is reported. Scheduled SU-MIMO mode of operation is optimized for a user reporting either a single antenna or multiple antennas, whereas MU-MIMO operation is optimized for a user reporting a single antenna.

An apparatus and method for transmitting/receiving data in a mobile communication system using multiple antennas are provided. A receiver estimates a fading channel of received data, selects a weight set relative to a maximum data transmission rate from at least one weight set with elements of a plurality of orthogonal weight vectors, and transmits feedback information including the selected weight set and channel-by-channel state information to a transmitter. The transmitter demultiplexes data to be transmitted on a basis of the feedback information into at least one sub-data stream, multiplies each sub-data stream by an associated weight, and transmits the data.

Systems and methods are described for coordinating transmissions in distributed wireless systems via user clustering. For example, a method according to one embodiment of the invention comprises: measuring link quality between a target user and a plurality of distributed-input distributed-output (DIDO) distributed antennas of base transceiver stations (BTSs); using the link quality measurements to define a user cluster; measuring channel state information (CSI) between each user and each DIDO antenna within a defined user cluster; and precoding data transmissions between each DIDO antenna and each user within the user cluster based on the measured CSI.

An apparatus for transmitting data in a base station of a wireless communication system that transmits data depending on channel status information fed back from terminals and uses a plurality of antennas. Based on the channel status information, a scheduler determines a terminal to which the base station will transmit data, determines antennas via which the base station will transmit data among the plurality of antennas, and determines a space pre-coding method. A multiplexer multiplexes transmission data into a plurality of data streams according to the number of the determined antennas. A modulation and coding unit performs modulation and coding on each of the data streams. A pre-coding controller outputs a matrix select signal for selecting one of a plurality of space pre-coding matrixes according to the space pre-coding method. A space pre-coder spatial-codes each of the coded streams with the matrix selected based on the matrix select signal. An OFDM modulator performs OFDM modulation on each of the spatial-coded streams. An RF unit transmits each of the OFDM-modulated streams via an associated antenna.

Sending channel related parameters known as channel state information (CSI) over a WLAN return channel. The size of these coefficients is not fixed. Rather, the coefficients are quantized in a certain resolution, which is determined adaptively according to a measure of the channel quality. This allows minimizing the component of the bandwidth of the wireless connection that is not used for payload transfer.

There is disclosed a method of a user equipment feeding back channel state information in a wireless communication system, comprising receiving a reference signal from a base station; generating first channel state information by measuring the reference signal; generating second channel state information based on the first channel state information; and transmitting the first channel state information and the second channel state information to the base station. The first channel state information is channel state information of a single user single cell Multi-input Multi-Output (MIMO) mode, and the second channel state information is channel state information of a multi-user MIMO (MU-MIMO) mode or a Cooperative Multiple Points Transmission and Reception (CoMP) mode.

Disclosed are an apparatus for Channel State Information-Reference Signal (CSI-RS) allocation and a method for CSI-RS transmission using the same in a wireless communication system. A CSI-RS for each antenna port is allocated to REs or subcarriers on a basis of a symbol or symbol axis in a subframe or Resource Block (RB), and is allocated in such a manner that a distance between neighboring CSI-RS allocation REs or subcarriers may be 3 REs or subcarriers. Accordingly, in the range of following CSI-RS transmission overhead, CSI-RSs are allocated to a time-frequency resource domain in such a manner so as to have perfect orthogonality or quasi-orthogonality according to cells or cell groups. Then, the CSI-RSs, which have been allocated to the time-frequency resource domain, are transmitted.

A method for feeding back transmitter beamforming information from a receiving wireless communication device to a transmitting wireless communication device includes a receiving wireless communication device receiving a preamble sequence from the transmitting wireless device. The receiving wireless device estimates a channel response based upon the preamble sequence and then determines an estimated transmitter beamforming unitary matrix based upon the channel response and a receiver beamforming unitary matrix. The receiving wireless device then decomposes the estimated transmitter beamforming unitary matrix to produce the transmitter beamforming information and then wirelessly sends the transmitter beamforming information to the transmitting wireless device.

A terminal device notifies a base station device about control information associated with a receive quality of the terminal device. The base station device performs data modulation on a plurality of pieces of transmit data for the terminal device, by using a plurality of different data modulation schemes one by one, based on the control information, and spatially multiplexes the plurality of pieces of transmit data after the data modulation over a single wireless resource and transmits a spatially multiplexed signal. The terminal device receives the signal with the plurality of pieces of transmit data spatially multiplexed, and detects desirable transmit data from the receive signal, based on a first channel matrix which represents channel state information between the base station device and the terminal device and a second channel matrix in which the first channel matrix is multiplied by a transform matrix. Accordingly, an adaptive modulation technology is applied even to MIMO spatial multiplexing transmission using a LR technology, and hence a wireless communication system and so forth that can contribute to improvement in frequency utilization efficiency can be provided.

A method of Coordinated Multipoint (CoMP) communication between a base station has a plurality of points with at least one user equipment (UE). At least one UE receives at least one transmission from the base station having the plurality of points. This UE measures downlink channel state information for each of the plurality of points including a rank indicator (RI), a precoding matrix indicator (PMI) and a channel quality indicator (CQI). This UE transmits the downlink channel station information in an uplink feedback channel to the base station.

A method includes receiving at least two space-time coded signals from an antenna system associated with a first station, determining complex channel state information based on the received space-time coded signals, and sending the complex channel state information to the first station. In an alternative embodiment, a method includes transmitting at least two space-time coded signals in respective beams of a multi-beam antenna array, measuring a channel impulse response for each space-time coded signal at a second station, and sending an indicia of a selected set of least attenuated signals from the second station to the first station. The multi-beam antenna array is associated with a first station. The beams transmit a signature code embedded in each respective space-time coded signal, and the signature codes are orthogonal so that the second station can separate and measure the channel impulse response corresponding to each space-time coded signal.

A method for transmitting channel status information (CSI) of downlink transmission via uplink in a wireless communication system includes transmitting a rank indicator (RI) and a precoder type indicator (PTI) at a first subframe, transmitting at a second subframe a first precoding matrix indicator (PMI) when the PTI has a first value and transmitting a second PMI and a wideband channel quality indicator (WB CQI) when the PTI has a second value, and transmitting at a third subframe a second PMI and a WB CQI when the PTI has a first value and transmitting a subband (SB) CQI and a second PMI when the PTI has a second value. A user equipment (UE) preferred precoding matrix is indicated by a combination of the first PMI and the second PMI. Subsampled codebooks of precoding codebooks of individual Rank-2, Rank-3 and Rank-4 are applied to the second PMI.

The transmit power of a mobile station on the reverse link channel that carries channel state information, rate selection, and/or sector selection information is power controlled separately from the reverse link traffic channels when the mobile station is in soft handoff. The serving base station in the active set for the mobile station controls the mobile station transmit power on the rate control channel. The non-serving base stations control the transmit power on the reverse traffic channel.