370 results about "Mimo systems" patented technology

Frequency-independent eigensteering in MISO and MIMO systems are described. For principal mode and multi-mode eigensteering, a correlation matrix is computed for a MIMO channel based on channel response matrices and decomposed to obtain N_S frequency-independent steering vectors for N_S spatial channels of the MIMO channel. ND data symbol streams are transmitted on N_D best spatial channels using N_D steering vectors, where N_D=1 for principal mode eigensteering and N_D>1 for multi-mode eigensteering. For main path eigensteering, a data symbol stream is transmitted on the best spatial channel for the main propagation path (e.g., with the highest energy) of the MIMO channel. For receiver eigensteering, a data symbol stream is steered toward a receive antenna based on a steering vector obtained for that receive antenna. For all eigensteering schemes, a matched filter is derived for each receive antenna based on the steering vector(s) and channel response vectors for the receive antenna.

Previous MIMO systems have used spatially diverse antenna elements in order not to reduce the number of orthogonal channels that can be realised. The present invention recognises that this leads to large antenna sizes, as compared to multiple beam antenna systems which use closely spaced antenna elements. In order to provide a compact antenna unit, while still allowing a MIMO system to be exploited, the present invention recognizes that polarization diversity only can be used in a MIMO system without the need for spatially diverse antenna elements. Closely spaced antenna elements are used and this enables a compact MIMO antenna unit to be provided. In addition, such MIMO systems with polarization diversity but no spatial diversity can advantageously be used in line of sight situations and also combined with multi-beam antenna systems to further increase capacity.

A method is presented for processing signals of a multiple-input, multiple-output communications system in the RF domain. The system includes multiple transmit antennas and multiple receive antennas connected by a wireless channel. A matrix M is generated based on long-term characteristics of the wireless channel. The matrix M is multiplied times input RF signals to obtain output RF signals. The matrix can be generated in a transmitter, a receiver, or both.

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).

In a closed-loop wireless communication system (200), a codeword retransmission scheme is provided which allows retransmission of a single codeword using a higher order transmission rank, which may or may not be the same as the higher order transmission rank used to originally transmit the codeword. When one of a plurality of codewords (CW1, CW2) being transmitted over two codeword pipes to a receiver (201.i) fails the transmission, codeword retransmission is enabled by duplicating the failed codeword at the base station (210) and then retransmitting the duplicated codewords over both codeword pipes using the same transmission layers or “rank” as the original transmission.

Multi-user (MU-) MIMO systems with quantized feedback are designed to maximize the sum-rate via scheduling and linear precoding. To maximize throughput over the network, quantized CSIT is sent through a low-rate feedback link feedback from a plurality of users back to a base station. The base station then determines a subset of the plurality of users to transmit one or more signals to based on the received feedback and determines a preceding matrix based on the received feedback from the plurality of users wherein the precoding matrix maximizes a sum-rate throughput for the subset of the plurality of users. Additionally, based on the received feedback, the base station designs a quantization codebook. This codebook may be designed off-line and/or online. The codebook and/or precoding matrix are used to transmit signals to the users.

In a closed-loop wireless communication system, a codebook-based feedback control mechanism is provided where feedback from each of a plurality of receivers is scheduled to control the feedback so that the receiving devices do not needlessly feed back precoding information to the transmitting device. The feedback may be controlled by establishing and distributing a schedule to control when each receiver feeds back preceding information, or by establishing and distributing a metric-based feedback threshold that must be satisfied before feedback is permitted.

Methods, devices and systems are provided for transmitting and receiving MIMO signals. Transmitting of the MIMO signals involves pre-coding each of at least two data symbols using a respective pre-coding codeword to preclude a corresponding plurality of pre-coded data symbols. A respective signal is transmitted from each of a plurality of antennas, the respective signal including one of the pre-coded signals and at least one pilot for use in channel estimation. The signals collectively further include at least one beacon pilot vector consisting of a respective beacon pilot per antenna, the beacon pilot vector containing contents known to a receiver for use by the receiver in determining the codeword used to pre-code the at least one data signal. Receiving of the MIMO signals involves receiving a MIMO signal containing data symbols pre-coded with a codeword. The MIMO signal includes pilots, and including at least one beacon pilot vector containing contents known to a receiver/each beacon pilot vector containing one symbol from each transmit antenna. Processing is performed on the at least one beacon pilot vector to determine which codeword was used to pre-code the data symbols.

The present invention provides a design framework that is used to develop new types of constrained turbo block convolutional (CTBC) codes that have higher performance than was previously attainable. The design framework is applied to design both random and deterministic constrained interleavers. Vectorizable deterministic constrained interleavers are developed and used to design parallel architectures for real time SISO decoding of CTBC codes. A new signal mapping technique called constrained interleaved coded modulation (CICM) is also developed. CICM is then used to develop rate matching, spatial modulation, and MIMO modulation subsystems to be used with CTBC codes and other types of codes. By way of example, embodiments are primarily provided for improved 5G LTE and optical transport network (OTN) communication systems. Detailed descriptions of embodiments are also provided that combine aspects of MIMO and spatial modulation systems to improve bandwidth efficiency. Such embodiments are applicable to multi-antenna and single antenna MIMO systems as well as multichannel systems, OFDM systems, and TDM systems.

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 telecommunications system described herein implements a multi-rank beamformer for use in wireless systems equipped with multiple transmit and multiple receive antennas. The multi-rank beamformer uses finite-rate feedback of channel conditions to achieves close to theoretical performance indicated by the water-filling algorithm, while avoiding the computational complexity associated with space time codes. In addition, the multi-rank beamforming system described herein improves on the performance of unit rank beamforming methods by maintaining the gains over space time codes over a broader range of transmission rates.

This disclosure describes techniques for providing active interference cancellation in a wireless communication system having a Bluetooth transmit chain and a WLAN receive chain. A signal sampled from the Bluetooth transmit chain is gain and phase adjusted to offset interference in the WLAN receive chain. A quadrature phase shifter may be used to generate quadrature components of the sampled signal that are selectively combined to achieve a desired phase adjustment. The phase shifter may be stabilized by a variable capacitor. These techniques may be extended to MIMO systems.

Detection for a MIMO (multiple-input, multiple-output) wireless communications system with symbols iteratively detected in subsets with maximum likelihood hard decisions within subsets. Previously detected subsets of symbols are used to regenerate corresronding input signals for interference cancellation. With a 4-transmitter antenna, 4-receiver antenna system, two subsets of two symbols are possible with the first two symbols detected with zero-forcing or MMSE soft estimates which feed maximum likelihood hard decisions; and the hard decision for the first two symbols are used for interference cancellation followed by zero-forcing or MMSE soft estimates for the second two symbols which then feed further maximum likelihood hard decisions.

A method and apparatus is disclosed herein for a modified soft output M-algorithm. In one embodiment, the soft output M-algorithm is employed by a receiver in a wireless communication system to receive information-bearing signals wirelessly transmitted from the transmitter wirelessly transmitted, the receiver comprising: an inner decoder structure having a multiple-in multiple-out (MIMO) joint demapper to perform joint inner demapping over each tone, the joint demapper being operable to apply a soft-output M-type algorithm to identify survivor candidates at each depth in a detection tree being searched for each tone, including surviving full-length candidates, based on at least one metric and at least one other criterion, where a number of best alternatives from every level of the tree are expanded along with one or more alternatives selected meeting the at least one other criterion and where soft-output related information is collected and stored for each bit, and an outer decoder operable with the inner decoder to perform iterative decoding.

The invention relates to a method for building sets of mobile stations in a radio communication network (RCS1), wherein the method comprising the steps of: transmitting (M1/1) reference signals from a base station (BS1) to at least two mobile stations (MS1, MS2, MS3) for being able to determine channel properties of a downlink channel (DL1) between the base station (BS1) and the at least two mobile stations (MS1, MS2, MS3); determining (M1/3, M1/4, M1/5, M1/6) a first feedback information at a first one of the at least two mobile stations (MS1, MS2, MS3) and a second feedback information at a second one of the at least two mobile stations (MS1, MS2, MS3) each comprising a first component indicating a channel quality; transmitting (M1/7) the first and the second feedback information from the first one and the second one of the at least two mobile stations (MS1, MS2, MS3) to the base station (BS1); and building (M1/9) a mobile station set according to the first and the second feedback information at the base station (BS1), wherein the channel quality is a parameter of a downlink beam with a largest received carrier power of at least three downlink beams (DB1, DB2, DB3, DB4) of said downlink channel (DL1).

A MIMO wireless system includes a transmitter that has a transmitter having a parser that parses a bit stream into multiple spatial data streams and multiple interleavers corresponding to the multiple spatial data streams, where each interleaver interleaves the bits in the corresponding spatial data stream by performing multiple column rotation to increase diversity of the wireless system. The MIMO wireless system also includes a receiver that has deinterleavers that deinterleaves spatial bit streams transmitted by the transmitter.

A method of performing receive antenna selection is presented. The method executes a determination operation for a set of receive antennas, determines a maximum result of the determination operation for two of the antennas, eliminates one of the two antennas from the set of antennas, and repeats the determination and elimination process until only a predetermined number of antennas remain in the set. The signals from these remaining antennas are then processed. The present invention reduces receiver complexity and cost.

Method and apparatus for decoding a transmitted signal by a receiver in a MIMO system into a first estimate component for estimating a first signal, a first interference component indicating interference resulting from a correlation relationship among a set of signals to be transmitted, and a first noise component. A base station generates the transmitted signal from the set of signals through a coding process, the coding process defining a correlation relationship amongst the set of signals. The correlation information about the correlation relationship is transmitted to the receiver directly or by a dedicated reference symbol. The decoding is performed by determining a linear receiver filter for the first signal in accordance with the correlation information, and de-correlating the first signal and interferences.

Systems and methods are provided for decoding signal vectors in multiple-input multiple-output (MIMO) systems, where the receiver has received one or more signal vectors from the same transmitted vector. The receiver combines the received vectors by vector concatenation The concatenated vector may then be decoded using, for example, maximum-likelihood decoding. In some embodiments, the combined signal vector is equalized before decoding.

A diversity transmission scheme uses a number of antennas that is greater than the limitation of two transmitting antennas in the well-known Alamouti scheme. In an embodiment comprising four antennas, the antennas transmit in pairs such that each antenna transmits a block that is used in the Alamouti scheme. This increases the transmission rate. For example, the transmission of two signals at a given time slot increases transmission rate by a factor of two. The invention not only increases the number of antennas, but also increases the transmission rate. At the receiver end, the code is decoded without matrix inversion and without much noise enhancement. Moreover, noise enhancement stability is increased by a simple, partial interference cancellation scheme, that results in improved decoding performance.