448 results about "Multi-user MIMO" patented technology

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 multi-user MIMO downlink beamforming system with limited feedback (200) is provided to enable preceding for multi-stream transmission, where a channel codeword (u_i) and one or more channel quality indicator values (CQI_A, CQI_B) are computed at the user equipment (201.i) on the basis of maximizing a predetermined SINR performance metric (ρ_i) which estimates the receive signal-to-noise-ratio (SINR) at the user equipment (201.i). The computed codeword (u_i) and CQI values (or differential values related thereto) are quantized and fed back to help the base station (210) which applies a correction to the appropriate CQI value in the course of designing the transmit beamforming vectors w and determining the appropriate modulation and coding level to be used for downlink data transmission.

The present invention provides a method for feedback and transmission of multi-user (MU) multiple input multiple output (MIMO) in a wireless communication system. The method includes steps of selecting subset codebook or full code book based on traffic load of a base station, and broadcasting the selected codebook to user equipments. In high traffic load, subset codebook is selected, and in low traffic load, full codebook is selected. User stations calculated a channel quality indicator of a spatial codeword vector that is included in the selected codebook. Information of the maximum channel quality indicator is sent to the base station together with a precoder of the user equipment. The base station selects user equipments based on the information of the maximum channel quality indicator and precoder, and transmits precoder signal and data signal to the user equipments. The present invention also provides a system for the base station that causes the base station to perform the above mentioned operations.

Systems and methods are described that provide not only time but also phase synchronization, thus enabling distributed multiuser multiple-input multiple-output (MIMO) architectures and techniques, such as supported by the IEEE 802.11n standard, where several access points are connected to a central server and operate as a large distributed multi-antenna access point. The systems and methods can lock the phase of all access points using a common reference (e.g., a synchronization tone) broadcasted over the air in conjunction with a predictive filter (e.g., a Kalman filter) which closely tracks the phase drift for each subcarrier channel.

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.

A multi-user MIMO downlink beamforming system (200) is provided to enable transmit beamforming vectors to be efficiently provided to a subset of user equipment devices (201.i), where spatial separation or zero-forcing transmit beamformers (w_i) are computed at the base station (210) and used to generate precoded reference signals (216). The precoded reference signals (216) are fed forward to the user equipment devices (201.i) which apply one or more hypothesis tests (207.i, 208.i) to the precoded reference signals to extract the precoding matrix (W), including the specific transmit beamforming vector (w_UE) designed for the user equipment, and this extracted information is used to generate receive beamformers (v_i).

A multi-user MIMO downlink beamforming system with limited feed forward (200) is provided to enable preceding matrix information to be efficiently provided to a subset of user equipment devices (201.i), where zero-forcing transmit beamformers (w_i) are computed at the base station (210) and assembled into a precoding matrix (W). The precoding matrix is encoded using a compact reference signal codebook (225, 207.i) for forward link signaling, either by sending bits indicating the index of the transmission matrix used, or by transmitting one or more precoded pilots or reference signals wherein the pilot signals are precoded using vectors uniquely representative of the transmission matrix used which includes candidate reference signal matrices which meet a predetermined condition number requirement, such as a condition number threshold. The preceding matrix information (227) is extracted at the user equipment devices (201.i) using the compact reference signal codebook (207.i) and used by the MMSE receiver (209.i) to generate receive beamformers (v_i).

A method transmits and receives signals in a cooperative, multi-user, multi-input, multi-output network. The network includes base stations (BSs) and mobile stations (MSs). Each BS has at least two antennas, and each MS has at least one antenna. At a first base station and a second base station using linear pre-coding matrices, a plurality of data streams are jointly pre-coded to produce first signals and second signals. The first signals are transmitted synchronously from the first BS and the second BS to a first MS, and the second signals are transmitted synchronously from the first BS and the second BS to a second MS, and in the first signal and the second signal are asynchronous with respect each other.

Precoding methods and method for performing precoding and methods of transmitting feedback information for precoding or transmitting a signal using a multi-codebook and method of transceiving precoding information in a multi-antenna system, where a signal transmitting method in a multi-antenna system, and more particularly, a method of transceiving precoding matrix information for a multi-input multi-output (MIMO) system is disclosed. The present invention proposes a method of performing communications using an expanded unitary matrix generated from shifting a phase of a base unitary matrix. The present invention is applicable to single user MIMO, multi-user MIMO, beam forming, etc.

A subchannel scheduling method in a multi-user MIMO-OFDM environment modifies proportional fairness scheduling specifications and maximizes a system throughput under conditions that a minimum data transmission rate required by a multimedia user be ensured. In a method for allocating subchannels in a wireless network, plural users are subscribed in the wireless network, a base station has N_T transmission antennas, a user i has N_R reception antennas, a network capacity determined by the N_T transmission antennas and K subcarrier groups is divided into K transmission subchannel groups, and a network bandwidth determined by the N_T transmission antennas is divided into the K subchannel groups. The base station sequentially allocates channels to the users on the basis of a proportional value of a data transmission rate supported to each user and an average throughput of each user in a predetermined time and a service quality required by each user.

A method of transmitting and receiving a specific reference signal in single point transmission and multi-point transmission is disclosed. The specific reference signal transmission method includes determining specific reference signal transmission resources for at least one terminal targeted for transmission, and transmitting the specific reference signal using the determined transmission resources and notifying of information for a layer used by the terminal. The specific reference signal transmission method includes determining specific reference signal reception resources, receiving the information for the layer used by the terminal from a serving cell base station, and receiving the specific reference signal using the information for determined transmission resources and the layer. Therefore, the terminal can recognize a position and a sequence of the specific reference signal. Particularly, in the case of multi-user MIMO and cooperative scheduling, signal interference can be suppressed or removed using the specific reference signal of another terminal.

An apparatus and method for transmission and reception in a multi-user Multiple-Input Multiple-Output (MIMO) communication system are provided. In a transmitter, a filter portion receives quantized Channel State Information (CSI) and Channel Quality Information (CQI) from a receiver, calculates a transmit filter value using on the quantized CSI and the CQI, determines an appropriate AMC level for the receiver, and sends a pilot signal including the transmit filter value and information about the determined AMC level on subcarriers in one of a preamble and data symbols. An antenna is used to send the output of the filter portion and receives data from the receiver.

A method of pairing users for an uplink multi-user multiple-input-multiple-output (MU-MIMO) system under coordinated multipoint transmission (CoMP) scenario in a communication system, which includes: selecting, by a first cell of the communication system, at least one initial user served by the cell as a first paired user; selecting, by the first cell, a candidate paired user according to the service type of the first paired user; and determining, from the different service types of the first paired user and the candidate paired user, a pairing type to be formed, and determining whether the candidate paired user and the first paired user can be paired into the pairing type to be formed by using a predetermined determination criterion according to the pairing type. It is further provided a device for performing the method. The throughput and communication efficiency of the communication system can be improved with the method and device for pairing users.

The invention provides a user selecting method of a multi-user MIMO communication system based on a codebook. An e Node B groups and selects dispatch users according to a PMI and a CQI feedback of users in a cell. The dispatch users are grouped according to the quasi orthogonality among codebook vectors expressed by the PMI. When the system runs, the e Node B ensures a signal path area which belong to each user according to the PMI feedback by a UE, selects a user with the maximal CQI to be taken as an optimum user of the area in the signal path subarea according to the CQI reported by the UE, computes the combined spectrum efficiency of each paired user group according to a previously set quasi orthogonality relationship, and selects one group of users with the largest combined spectrum efficiency to be taken as the current paired user group. The method can greatly simplify the computing complexity selected by the user in the multi-user MIMO communication system and can obtain the throughput performance near the optimum.

Disclosed is a method for generating and transmitting a reference signal in a clustered DFT-spread OFDM transmission scheme. A method for generating and transmitting a DM-RS in a clustered DFT-spread-OFDM scheme comprises: a step of generating DM-RS sequences corresponding to the number of clusters allocated for an uplink transmission; and a step of mapping the generated DM-RS sequences to the relevant DM-RS symbol positions for each cluster. Accordingly, the method for generating and transmitting a reference signal according to the present invention, in which DM-RS sequences are allocated and transmitted on a cluster basis, uses a complete DM-RS sequence for each cluster, and therefore inter-cell interference can be weakened, and problems which might occur when applied to a multi-user MIMO (MU-MIMO) scheme can be solved.

A wireless communication system includes an intermediate node, a first node and a second node. There is described a method for implementing MIMO based network coding, comprising the first node transmitting first data to the intermediate node, and the second node transmitting second data to the intermediate node. Both the first node and the second node may use spatial multiplexing or time division multiplexing or frequency division multiplexing on a common/different resource. The intermediate node receives the transmissions from the first node and second node, and performs network coding on the first data and second data using a predefined network coding scheme to produce network coded information. The intermediate node transmits the network coded information to the first node and second node using multi-user MIMO; and; each first or second node receives the MIMO transmissions from the intermediate node and applies network decoding procedures to recover the first data and second data. Network coding schemes include Decode and Forward (DF), Map and Forward (MF) and Amplify and Forward (AF). The first node and second node may be members of groups of nodes all within the same coverage area. A method for scheduling MIMO-based network coded transmissions is also described. Hybrid Automatic Repeat Request (HARQ) transmission may also be network encoded.

A method for utilizing user feedback to dispatch user in a wireless multi-user MIMO communication system, including: selecting a user who synchronously receives services in multi-user MIMO transmission by a base station and each data stream number assigned to the selected user as a dispatched result, generating s pre-coding matrix based on obtained dispatched result for selected user; multiplying the pre-coding matrix and user data stream to generate a data sequence after pre-coding; generating a pilot signal for the selected user, and sending the generated pilot signal and the generated pre-coding data sequence to a user end; estimating a signal power and an interfere power when the user end receives the pilot signal, and estimating a noise power; determining whether there is a need to reduce the user number synchronously serviced by the multi-user MIMO communication system based on the obtained signal power, interfere power and noise power, and feeding back the determined result to the base station; adjusting the user number synchronously serviced by the multi-user MIMO communication system by the base station based on the received feedback result.

A transmission/reception apparatus and method for reducing the amount of feedback information transmitted from a receiver in a multi-user MIMO system are provided. A transmitter determines a reference Channel Quality Information (CQI) and transmits the reference CQI to the receiver. Upon receipt of the reference CQI, the receiver compares the received reference CQI with a CQI of a stream received from the transmitter, sets a channel, over which the stream is received, to at least one of Activation and Inactivation, according to the comparison result, and transmits the set channel information to the transmitter. As a result, the receiver, even though it receives multiple streams from the transmitter, transmits to the transmitter the at least one of Activation and Inactivation information of the channel separately for each individual stream, thereby contributing to a reduction in the total amount of feedback information.

To optimize the selection of pre-coding vectors in a multi-user MIMO system, the present invention provides a method for selecting pre-coding vectors in a base station, comprising the steps of: transmitting a plurality of pilot signals without being precoded to the plurality of terminals; receiving a plurality of feedback signals from the plurality of terminals, wherein at least one feedback signal includes a plurality of recommended pre-coding vector information and a plurality of channel status information, and each of the channel status information corresponds to a recommended pre-coding vector information; generate a pre-coding codebook based on the plurality feedback signals, wherein at least one pre-coding vector in the pre-coding codebook is determined based on a correlation coefficient between at least two recommended pre-coding vectors; and performing a transmission operation using the pre-coding codebook. Through considering the correlation among pre-coding vectors and different channel status information corresponding to different pre-coding vectors, be used to extend the selection range of pre-coding vectors and improve the total transmission rate of the whole system and system capacity.