Nec Laboratories America, Inc.

Nec Corporation

Nec Laboratories Aemrica, Inc.

Mohammad Madihian

Xiaodong Wang

Narayan Prasad

Mohammad Ali Khojastepour

Guosen Yue

Aimin Sang

Kai Li

Seung-Jun Kim

Karthikeyan Sundaresan

Jibing Wang

Xiadong Wang

Shuangquan Wang

Milan Kovacevic

Babak Soltanian

Chuxiang Li

Ignacio Berenguer

Min Cao

Ben Lu

A method implemented in a base station used for a downlink multi-user (MU) multi-input multi-output (MIMO) system is disclosed. The method includes receiving an indication of a quantized matrix from each of a plurality of scheduled user equipments, precoding data streams for the plurality of scheduled user equipments, transmitting the precoded data to the plurality of scheduled user equipments. Other methods and some apparatuses for wireless communications also are disclosed.

Multi-user downlink linear MIMO precoding system

A method implemented in a mobile communications system for data transmission is disclosed. The method includes selecting a set of parallel channels, determining transmission rank, and determining a precoding matrix of the transmission rank for the set of parallel channels, wherein the precoding matrix is formed by applying householder transformation to a vector to make a matrix and selecting one or more columns from the matrix. Other methods and apparatuses also are disclosed.

Transmission of an information sequence

A method for wireless encoding includes encoding wireless multiple input and multiple output signals in accordance with a codebook being one of a discrete codebook restricting elements of codebook entries to be within a predetermined finite set of complex numbers and a constant amplitude codebook including each entry in its codebook having equal column norm and equal row norm. In a preferred embodiment the digital codebook further includes restricting elements of a finite set in the discrete codebook to be in the form of k+jkfor a base-k computer and the constant amplitude codebook further includes being obtained through a series of successive householder transformations. In a preferred embodiment the codebook is configured as one of a constrained codebook in which the codebook is configured for multiple scenarios and a discrete codebook.

Codebook method for a multiple input multiple output wireless system

An encoding of K blocks of information for transmission on N subchannels, responsive to a number of redundant blocks M, employs one of multiple check codes depending on the number of redundant blocks M and employs multiple processes for determining a code for the K blocks of information depending on the number of redundant blocks M and K blocks of information together.

Anti-jamming piecewise coding method for parallel inference channels

A cross-layer optimization framework for designing of multi-radio/multi-channel wireless mesh networks with network coding to support multiple unicast applications is used. A column-generation-based primal-dual method is used to solve the optimization problem. For network-layer formation, a code construction scheme based on linear programming is used. Delay constraints are imposed on the network code construction so the possible impact of the extra decoding delay to the upper-layer Transmission Control Protocol/Internet Protocol (TCP/IP) performance may be reduced without changing the upper-layer protocols.

Method and apparatus for optimization of wireless mesh networks

A decoder and method for iteratively decoding of low-density parity check codes (LDPC) includes, in a code graph, performing check node decoding by determining messages from check nodes to variable nodes. In the code graph, variable node decoding is performed by determining messages from the variable nodes to the check nodes. The variable node decoding is independent from degree information regarding the variable nodes. Decoded results are output.

Efficient low complexity high throughput LDPC decoding method and optimization

A scheduling system and method for use with relay-assisted wireless networks includes accessing feedback from mobile stations in a network and arranging users associated with a relay station in a list in accordance with marginal utilities. A determination of whether the users in the list can be eliminated from feedback overhead by testing conditions for feedback reduction is made. A diversity schedule is generated by employing a weighted bipartite graph with relay channels and access channels and performing a matching method. A transmission schedule is generated for channel usage in accordance with multi-user and channel diversity for mobile users and spatial reuse of channels across relay and access hops by incorporating rate feedback and interference for the mobile stations and the relay stations based upon the matching method applied to a new weighted graph which accounts for traffic loads and fairness as well.

System and method for scheduling in relay-assisted wireless networks

The invention is a method directed to group MMSE-DFD with rate (SINR) feedback and without pre-determined decoding order for reception on a cellular downlink. The method includes initializing channel matrix estimates and inner codes of all co-channel transmitter sources in a wireless network. Each channel matrix estimate is converted into an effective channel matrix responsive to the inner code of the corresponding transmitter source; The channel estimates or the inner codes or the modulation and coding schemes are not known for some of the transmitter sources whose transmitted signals are consequently treated as interference and deemed un-decodable.

Group MMSE-DFD with rate (SINR) feedback and without pre-determined decoding order for reception on a cellular downlink

Methods and apparatus for designing spherical lattice codebooks for use in data transmission systems are provided. A spherical lattice codebook is constructed by determining the channel statistics of one or more channels, which can be accomplished by observing a sufficiently large set of channel realizations. After determining the channel statistics, an expression for the error probability of the decoder or expressions for bounds on the error probability and expressions for the corresponding gradients are determined. The gradient is then used in an optimization technique to produce a spherical lattice codebook which is subsequently used for transmission.

Spherical lattice codes for lattice and lattice-reduction-aided decoders

The present method resides in a user destination receiver to exploit the structure of the transmitted signals to design filters that yield improved performance. Moreover, the computational cost of designing these filters can be reduced and the demodulation complexity can be kept low. Further, the present method enables determining the order of decoding the transmitter sources. The present method provides group MMSE decision feedback decoding for the case when all the sources transmit at fixed pre-determined rates and the MCS employed by each source is known to the destination. The present method includes a filtering technique and an order and filter computation process, both improvements over previous efforts at group MMSE decision feedback decoding.

Group MMSE-DFD with order and filter computation for reception on a cellular downlink

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.

Multi-user downlink linear MIMO precoding systems

A method for filtering in a wireless downlink channel, where all dominant transmitting sources use inner codes from a particular set, includes the steps of estimating a channel matrix seen from a desired transmitter source in response to a pilot or preamble signal; converting the estimated channel matrix into an effective channel matrix responsive to the inner code of the desired transmitting source; estimating a covariance matrix of noise plus interference in a linear model whose output is an equivalent of the received observations and in which the effective channel matrix corresponding to each dominant transmitting source inherits the structure of its inner code; computing a signal-to-noise-interference-ratio SINR responsive to the covariance matrix and the effective channel matrix corresponding to the desired source; and feeding back the computed SINR to the transmitter source.

Group LMMSE demodulation using noise and interference covariance matrix for reception on a cellular downlink

A method for decoding and rate assignment in a wireless channel, where all dominant transmitter sources use inner codes from a particular set, comprising the steps of: i) estimating channel matrices seen from all dominant transmitter sources in response to a pilot or preamble signal transmitted by each such source; ii) converting each estimated channel matrix into an effective channel matrix responsive to the inner code of the corresponding transmitter source; iii) obtaining the received observations in a linear equivalent form (linear model) whose output is an equivalent of the received observations and in which the effective channel matrix corresponding to each dominant transmitter source inherits the structure of its inner code; iv) processing the transmitter sources according to the specified (or pre-determined) order of decoding; v) for each transmitter source, assuming perfect cancellation of signals of preceding transmitter sources; vi) computing a signal-to-interference-noise-ratio SINR responsive to the effective channel matrix of the transmitter source and the covariance matrix of the noise plus signals from remaining transmitter sources; and vii) feeding back all computed SINRs to respective transmitter sources.

Group MMSE-DFD with rate (SINR) feedback and pre-determined decoding order for reception on a cellular downlink

A method includes the steps of i) listing out all possibilities for a first symbol of a two stream signal; ii) determining a second symbol of the two stream signal for each of the first symbol listed out, iii) evaluating a metric for each of the first symbol and second symbol pair, iv) listing out all possibilities for second symbol, v) determining a first symbol for each choice of the second symbol listed out, vi) evaluating a metric for each of the second symbol and first symbol pair, vii) determining an exact maximum log likelihood ratio for all bits using the metrics, and viii) decoding codeword(s) in the two stream signal using the determined exact maximum log likelihood ratio for all bits.

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Plainsboro, NJ, United States of America

Mohammad Madihian