500 results about "Mimo communication systems" patented technology

For an incremental redundancy (IR) transmission in a MIMO system, a transmitter processes (e.g., encodes, partitions, interleaves, and modulates) a data packet based on a selected rate to obtain multiple data symbol blocks. The transmitter transmits one data symbol block at a time until a receiver correctly recovers the data packet or all blocks are transmitted. Whenever a data symbol block is received from the transmitter, the receiver detects a received symbol block to obtain a detected symbol block, processes (e.g., demodulates, deinterleaves, re-assembles, and decodes) all detected symbol blocks obtained for the data packet, and provides a decoded packet. If the decoded packet is in error, then the receiver repeats the processing when another data symbol block is received for the data packet. The receiver may also perform iterative detection and decoding on the received symbol blocks for the data packet multiple times to obtain the decoded packet.

For incremental redundancy transmission on multiple parallel channels in a MIMO system, a transmitter processes (e.g., encodes, partitions, interleaves, and modulates) each data packet for each parallel channel based on a rate selected for the parallel channel and obtains multiple symbol blocks for the packet. For each data packet, the transmitter transmits one symbol block at a time on its parallel channel until a receiver recovers the packet or all blocks have been transmitted. The receiver performs detection and obtains symbol blocks transmitted on the parallel channels. The receiver recovers the data packets transmitted on the parallel channels independently or in a designated order. The receiver processes (e.g., demodulates, deinterleaves, re-assembles, and decodes) all symbol blocks obtained for each data packet and provides a decoded packet. The receiver may estimate and cancel interference due to recovered data packets so that data packets recovered later can achieve higher SINRs.

The present invention provides the multiuser Multiple-Input Multiple-Output (MIMO) systems with a feedback method which includes measuring, at the terminal, received Signal to Noise Ratios (SNRs) for all transmit antennas, selecting one of precoding matrixes, which has best SNRs, retrieving an index mapped to the selected preceding matrix from a predetermined mapping table, and transmitting the index with the SNRs of the selected precoding matrix. In the present invention, it is possible to reduce feedback information amount without degradation of the sum rate performance of the system since the feedback information is transmitted in a form of index implying appropriate precoding matrix and corresponding SNRs.

A beam and power allocation method for a MIMO system transmitting multiple data streams from a transmitter having a plurality of transmit antennas to a receiver having at least two receive antennas, the transmit antennas being grouped based on feedback information from the receiver, includes obtaining covariance matrices for respective transmit antenna group, and allocating beam and power to the transmit antenna groups according to the covariance matrices of the respective antenna groups. The power allocation method can be adapted to various partial beamforming techniques by generalizing the optimization problem as a function of transmit covariance matrices.

Disclosed is a transmission method for a downlink control signal in a MIMO communication system where multiple transmit antennas and multiple receive antennas are used, in which each data transmitted from the multiple transmit antennas is transmitted with a different control signal through one downlink control signal transmission channel. The transmission method for a downlink control signal in a MIMO communication system efficiently transmits or receives data by transmitting control information such as a different modulation method and the number of OVSF codes of each transmit antenna to a mobile station. Also, a control channel is similar to that used in the conventional HSDPA system, thus allowing backward compatibility. Additionally, the transmission method can be applied not only for data transmitted to each antenna being composed of one packet but also for data transmitted to each antenna being composed of multiple packets.

A MIMO communication system capable of adaptive user scheduling. The MIMO communication system comprises a transmitting terminal, which sends data frames containing at least channel estimation signal and user data, and at least one receiving terminal, which recovers the user data and generates corresponding feedback information. The feedback information comprises an optimal transmitting antenna set dedicated to the receiving terminal, the achievable channel capacity by each antenna within the antenna set, and the degradation factors caused by each of other unselected antennas to each of the selected antennas. Depending on the feedback information, the transmitting terminal generates scheduling information based on which the adaptive user scheduling is conducted. The scheduling information comprises the scheduled users, number of data streams supported by each scheduled user, and the corresponding transmitting antenna for each of the data streams. The MIMO system can achieve the optimal channel capacity through adaptive user scheduling.

A process for beamforming data to be transmitted in a MU-MIMO communication system comprising a base station and a selected set of User Equipments (UE) communicating with said base station; said data being precoded by said base station in accordance with a beamforming matrix complying with a precoding matrix under the form of: (formula 1) Where—M is the number of transmit antennas—D is a diagonal unitary matrix of the form D=diag (formula 2)—P is a permutation matrix interchanging only the last M−1 rows. —A is a general Hadamard matrix. and that the signaling information transmitted by the base station to the UE comprises at least a first and a second index which are representative of D, P and A.

A data transmission method in a MIMO-OFDM communication system including at least one receiver for receiving a signal through a plurality of reception antennas and a transmitter for selecting a transmission channel using channel information being fed back from the receiver and transmitting a signal through a plurality of transmission antennas. The method includes selecting a spatial subchannel in which when bits are added by applying at least two spatial modes having different multiplexing gains for an individual subcarrier in a frequency domain, the minimum power increment is required during application of each spatial mode; allocating a spatial mode that requires the minimum total accumulated power, for each subcarrier; and selecting all subcarriers in the order of a subcarrier that requires the minimum power increment.

In multiuser Multiple-Input Multiple-Output (MIMO) systems in which a base station performs scheduling on the basis of channel information fed back from a plurality of terminals, the user scheduling method of the present invention includes calculating a metric for scheduling the users using the channel information, selecting one of at least two preinstalled scheduling schemes according to the metric, and performing the scheduling with the selected scheduling scheme. The user scheduling method of the present invention performs scheduling with one of TDMA- and STMA-based scheduling schemes which show maximum capacity in different channel environments, such that the system capacity can be optimally maintained even when the channel environment is changed.

A multiple-input multiple-output (MIMO) wireless communication system. A transmitter that includes a plurality of transmit antennas selects one of a spatial multiplexing scheme and a spatial diversity scheme, processes a signal in the selected transmission scheme, and transmits the signal through the plurality of transmit antennas. A receiver that includes a plurality of receive antennas processes a signal in a reception scheme mapped to a transmission scheme of the transmitter. The transmission schemes include a transmission scheme for maximizing diversity gain and a transmission scheme for maximizing spectral efficiency. The MIMO communication system using an adaptive transmission mode switching technique performs switching between MIMO transmission modes using spatial selectivity of a channel, thereby obtaining maximum gain in a signal to noise ratio (SNR) and spectral efficiency according to channel state.

LDPC (Low Density Parity Check) coding and interleaving implemented in multiple-input-multiple-output (MIMO) communication systems. Initially, a novel approach is presented by which a wide variety of irregular LDPC codes may be generated using GRS or RS codes. These irregular LDPC codes can provide better overall performance than regular LDPC codes in terms of providing for lower BER (Bit Error Rate) as a function of SNR (Signal to Noise Ratio). A variety of communication device types are also presented that may employ the error correcting coding using a GRS-based irregular LDPC code, along with appropriately selected interleaving, to provide for even better performance. These communication devices may be implemented to in wireless communication systems including those that comply with the recommendation practices and standards being developed by the IEEE 802.11n Task Group (i.e., the Task Group that is working to develop a standard for 802.11 TGn (High Throughput)).

A transmitter beamforming technique for use in a MIMO wireless communication system determines a partial description of a reverse channel without determining a full dimensional description of the reverse channel. A correction matrix is developed from the partial description of the reverse channel and a description of the forward channel. The correction matrix is used to process signals to be transmitted via the forward channel, and a steering matrix is used to perform beamforming in the forward channel.

An automatic retransmission request control system in OFDM-MIMO communication system. In this system, an ACK / NACK output part (320) of a receiver transmits, to a transmitter, a feedback information of positive or negative response based on the result of a cyclic redundancy check. An error data stream decision part (310) of the transmitter determines, based on the feedback information, a data stream that need be retransmitted, and a retransmission mode selection part (312) selects a retransmission mode from among (a) a mode in which to transmit the data, which are to be retransmitted, via the same antenna as in the previous transmission, while transmitting, at the same time, new data by use of an antenna via which no data retransmission is requested; (b) a mode in which to transmit the data, which are to be retransmitted, via an antenna via which no retransmission is requested, while transmitting new data via another antenna at the same time; (c) a mode in which to use STBC to retransmit the data via an antenna via which no retransmission is requested; and (d) a mode in which to use STBC to retransmit the data via all the available antennas.

Soft symbol decoder algorithms for multiple input, multiple output (MIMO) receivers reduce the search complexity by searching over fewer than all possible combinations of transmitted symbols to compute log metrics for each transmitted bit from each transmit antenna. In one algorithm, a sub-optimal set of transmitted symbols is computed and the transmitted symbols are restricted to neighboring constellation points of the sub-optimal set. In another algorithm, all constellation points are searched for every antenna except one. In yet another algorithm, constellation points are searched excluding more than one antenna. The non-searched antenna(s) can be handled by either a bit stuffing or a soft slicing technique.

The present invention provides an effective way to create a virtual MIMO transmission system using mobile terminals that have only one transmit path and antenna. This is accomplished by assigning mobile terminals to a group and assigning certain shared resources and user-specific resources to those mobile terminals in the group. In a synchronized fashion, the mobile terminals will provide uplink transmission in concert, as if they were a single entity having multiple transmission paths and antennas. Preferably, the shared resources bear on how the data is transmitted, and the user-specific resources relate to pilot signals. The data transmitted may be encoded in any number of ways, and in one embodiment, the mobile terminals may relay their information to each other, such that uplink transmissions can incorporate STTD decoding or other space-time codes. The invention is applicable to virtually any multiple access technology, including OFDM, TDMA, and CDMA, preferably synchronous CDMA.

A MIMO communication system having deterministic channels wherein MIMO is applied to line-of-sight channels having a fixed geometrical positional relationship so as to increase the channel capacity. A line-of-sight MIMO communication system having a plurality of channels includes a channel matrix calculation processing section on a transmission or reception side or both of the transmission and reception sides. The channel matrix calculation processing section updates an orthogonal channel formation matrix in accordance with a fluctuation of a transmission antenna position or reception antenna position or a fluctuation of the channels.

A beamforming technique used in a MIMO wireless transmission system performs beamforming based on a subset of the receiver antennas within the communication system to increase the speed and / or to decrease the processing needed to implement effective beamforming at the transmitter of the MIMO system. This beamforming technique can provide increased performance over no beamforming without significantly increasing the processing overhead of the transmission system, especially when a large number of receiver antennas are present at a receiver of the MIMO system. This beamforming technique can additionally be used when a transmitter, with multiple transmission antennas, is used to communicate with multiple receivers, each of which includes one or more receiver antennas. In this case, the beamforming technique may select a subset of the receiver antennas that includes, for example, one receiver antenna from each of the receivers, and may then beamform to the selected subset of receiver antennas.

A solution for optimizing beamforming configurations and transmit power allocation configurations in a telecommunication system comprising a base station and a plurality of user entities is provided. The base station and the user entities are capable of multiple-input multiple-output (MIMO) communications, i.e. capable of communicating through spatial subchannels. The base station calculates iteratively optimal beamforming configurations for the base station and for each user entity and transmit power allocation configurations for each spatial subchannel used in MIMO communications. The base station carries out the calculation on the basis of channel state information received from the user entities by utilizing the information on correlation of different spatial subchannels, i.e. interference between the subchannels, in order to update beamforming configurations and transmit power allocation configurations.

Techniques for deriving eigenvectors based on steered reference and used for spatial processing. A steered reference is a pilot transmission on one eigenmode of a MIMO channel per symbol period using a steering vector for that eigenmode. The steered reference is used to estimate both a matrix Σ of singular values and a matrix U of left eigenvectors of a channel response matrix H. A matrix Ũ with orthogonalized columns may be derived based on the estimates of Σ and U, e.g., using QR factorization, minimum square error computation, or polar decomposition. The estimates of Σ and U (or the estimate of Σ and the matrix Ũ) may be used for matched filtering of data transmission received via a first link. The estimate of U or the matrix Ũ may also be used for spatial processing of data transmission on a second link (for reciprocal first and second links).

A Multiple-Input Multiple-Output (MIMO) communication system and method. The MIMO communication system includes: an antenna number determination unit to determine a number of active antennas among a plurality of transmitting antennas based on a power of a transmission signal wherein the number of active antennas is at least one and the at least one active antenna transmits the transmission signal; and a beam generator to generate the transmission signal corresponding to the number of active antennas by using channel information wherein the channel information is fed back from each of a plurality of user terminals.

The invention provides a generic and comprehensive architecture to optimise several space-time adaptive algorithms and their applications for both CCI and ISI interference cancellation for MIMO systems. The basic idea of this invention is to optimise space-only processes and time-only processes and their combination to take account of the varying affects of CCI and ISI in a given environment. This maximises the efficiency of adaptive algorithms. The invention is targeting on unknown CCI or co-antenna interference of other operating system at the same frequency band.

The invention provides a self-adaptive design method for an intelligent reflection phase shift matrix in a large-scale MIMO system. In a downlink, a base station transmits a signal through a large-scale antenna array, and an intelligent reflecting surface performs phase shift operation on the received signal and then reflects the received signal to a user. According to a corresponding communication environment, a phase shift matrix design method or a random phase shift matrix design method is adaptively selected and optimized. The phase shift matrix design is optimized by transmitting a single-frequency signal and optimizing the phase shift matrix of the intelligent reflecting surface under the criterion of maximizing the receiving power of the user side. The random phase shift matrix design randomly determines the phase of each reflective element. The method is easy to operate and low in calculation complexity, the two phase shift matrix design methods can obtain high power efficiency and spectrum efficiency, any channel state information of the intelligent reflecting surface is not needed, and the method has important significance for design and implementation of a large-scale MIMO communication system adopting the intelligent reflecting surface.

A method of controlling signal transmission in a Multiple Input Multiple Output (MIMO) communication system including selecting a modulation and code set (MCS) for each of M data streams transmitted via M transmitting antennas in a transmitting side of the MIMO system, and selectively selecting M-1 or fewer transmitting antennas from the M transmitting antennas for transmitting the data streams based on channel quality information indicative of a transmission performance of the selected MCS corresponding to each of the M transmitting antennas. In another example, the present invention provides a novel method of controlling signal transmission in a MIMO communication system including selecting M weight vectors for streams transmitted by each of M transmitting antennas in a transmitting side of the MIMO system, and selectively selecting M-1 or fewer streams and weight vectors from the M weight vectors for transmitting data streams based on channel quality information indicative of transmission performance of the selected weight vectors corresponding to each of the M vector spaces.

A MIMO communication system capable of adaptive user scheduling. The MIMO communication system comprises a transmitting terminal, which sends data frames containing at least channel estimation signal and user data, and at least one receiving terminal, which recovers the user data and generates corresponding feedback information. The feedback information comprises an optimal transmitting antenna set dedicated to the receiving terminal, the achievable channel capacity by each antenna within the antenna set, and the degradation factors caused by each of other unselected antennas to each of the selected antennas. Depending on the feedback information, the transmitting terminal generates scheduling information based on which the adaptive user scheduling is conducted. The scheduling information comprises the scheduled users, number of data streams supported by each scheduled user, and the corresponding transmitting antenna for each of the data streams. The MIMO system can achieve the optimal channel capacity through adaptive user scheduling.

An adaptive MIMO communications system includes a multifunctional reconfigurable antenna with a selectively alterable effective physical antenna array configuration and radiation / polarization properties, which configuration and properties is a component in the optimization of the adaptive system parameters. The multifunctional reconfigurable antenna comprises a plurality of antenna components and a plurality of selectively controllable switches coupling selected ones of the plurality of antenna components together into a multifunctional reconfigurable subarray of antenna components. A processing unit coupled to the multifunctional reconfigurable antenna determines communication channel conditions for generating adaptive control signals to the plurality of selectively controllable switches to selectively apply a selected space-time coding protocol or a selected beam forming protocol together on the plurality of antenna components depending on channel conditions.

A MIMO communication system implements an interleaver design with multiple encoders for more than two transmit antennas for high throughput WLAN communication systems. Multiple encoders are utilized in the transmitter and multiple decoders are utilized in the receiver, wherein each encoder operates at lower clock speed than would be necessary with a single encoder. In conjunction with using multiple encoders, a modified interleaving function for each spatial stream processing allows fully exploring the diversity gains. The provided interleaving function is suitable for transmitter architectures with multiple encoders. Similarly, a modified de-interleaving function is provided that is suitable for receiver architectures with multiple decoders.

The present invention employs a pilot scheme for frequency division multiple access (FDM) communication systems, such as single carrier FDM communication systems. A given transmit time interval will include numerous traffic symbols and two or more short pilot symbols, which are spaced apart from one another by at least one traffic symbol and will have a Fourier transform length that is less than the Fourier transform length of any given traffic symbol. Multiple transmitters will generate pilot information and modulate the pilot information onto sub-carriers of the short pilot symbols in an orthogonal manner. Each transmitter may use different sub-carriers within the time and frequency domain, which is encompassed by the short pilot symbols within the transmit time interval. Alternatively, each transmitter may uniquely encode the pilot information using a unique code division multiplexed code and modulate the encoded pilot information onto common sub-carriers of the short pilot symbols.

A MIMO communications system includes a transmitter, and a receiver synchronized with the transmitter. The transmitter changes the power levels for each layered space data stream on a time slotted basis. The data streams arrive at the receiver with various power levels, which provides suitable differences in the received signals for population of a mixing matrix for signal separation processing.

A method for transmitting and receiving a precoded signal in a Multi-Input Multi-Output (MIMO) communication system is provided. In the method, a preceding matrix is selected from a codebook including one or more preceding matrices of each rank, each of the preceding matrices including a unitary matrix modified by an antenna selection element. A signal for transmission is then precoded by applying the selected preceding matrix to the signal for transmission and the precoded signal is transmitted through a selected antenna.

The present invention provides a subcarrier index coordinator for use with a multiple-input, multiple-output (MIMO) transmitter having N transmit antennas, N being at least two, wherein each employs a plurality of transmit symbols with used subcarriers. The subcarrier index coordinator includes a subcarrier index generator configured to generate a set of pilot subcarrier indices and a set of data subcarrier indices for transmission. Additionally, the subcarrier index coordinator also includes a subcarrier index formatter coupled to the subcarrier index generator and configured to arrange the sets of pilot subcarrier indices and data subcarrier indices within the used subcarriers during transmission based on the N transmit antennas and the plurality of transmit symbols.