| Patent application number | Description | Published |
|---|
| 20080198911 | Equalizer for Single Carrier FDMA Receiver - A method of equalizing a received signal compensates for frequency selectivity of the communication channel taking into account channel estimation errors. The method comprises generating channel estimates for the received signal, computing filter weights for an equalizer based on said channel estimates and a covariance of the channel estimation error, and filtering the received signal using the computed filter weights. | 08-21-2008 |
| 20080205451 | TRANSMISSION SCHEME FOR UPLINK ACCESS IN A FDMA SYSTEM - Transmission scheme for the uplink of FDMA systems that improves performance in an interference-dominated system by using a pilot scheme that provides enough information so that channel estimates can be obtained for a particular user, but which at the same time makes it possible to use pilot patterns that are different in different cells so that co-channel interference is mitigated. A codeword is used to position a set of pilot symbols within a set of subcarriers wherein each subcarrier has a first pilot time slot and a second pilot time slot associated with one or more data time slots. The set of subcarriers are identified on which to transmit the composite signal and the first pilot time slots and the second pilot time slots are filled with the pilot symbols in accordance with the codeword. The composite signal is then formatted as a combination of modulated data and pilot signals. | 08-28-2008 |
| 20080274727 | Co-Sequence Interference Detection and Treatment - Signal properties of a signal section ( | 11-06-2008 |
| 20080279182 | Method and Apparatus for the Use of Network Coding in a Wireless Communication Network - According to a method and apparatus taught herein, a network node includes a receiver circuit that determines soft values for received packets corresponding to the information bit groups associated with network coding operations, where the soft values are determined for each information bit group based on joint probabilities of the information bits within the information bit group. For example, first soft values are determined for the information bit groups in a first (received) constituent packet and second soft values are likewise determined for the information bit groups in a network-coded (received) packet that depends on the first constituent packet and a second constituent packet. Third soft values are generated for the information bit groups of the second constituent packet based on jointly evaluating the first and second soft values. | 11-13-2008 |
| 20080282125 | Method and Apparatus for Combined Packet Retransmission and Soft Decoding of Combined Packets in a Wireless Communication Network - In a wireless communication network using point-to-point or point-to-multipoint communications, this disclosure teaches the use of combined packets for retransmission and corresponding soft value processing at a receiver, wherein combined packets are formed as the logical combination of two or more previously transmitted packets and allow the receiver to use a single combined packet to correct one or more failed packets. For example, with the combined packet retransmission and corresponding soft value receiver processing as taught herein, a given receiver can use a given combined packet to correct bit errors in all (failed) packets comprising the combined packet as long as the bit errors in a failed packet do not overlap (or align) with bit errors in the other failed packets comprising the combined packet. | 11-13-2008 |
| 20080310523 | Method and Apparatus for Controlling Multi-Antenna Transmission in a Wireless Communication Network - Multi-antenna transmission control presented herein involves generating a set of virtual channel realizations at the transmitter that shares the same second-order statistics as the actual channel realizations observed for a targeted receiver. By making the control-related quantities of interest at the transmitter depend on the long-term statistics of the channel, the actual channel realizations are not needed for transmission control, e.g., for accurate Multiple-Input-Multiple-Output (MIMO) preceding. As such, the use of virtual channel realizations enables transmission control that approaches the “closed-loop” channel capacity that would be provided by full feedback of the (instantaneous) actual channel realizations, without requiring the overhead signaling burden that attends full feedback. | 12-18-2008 |
| 20090016425 | Adaptive Compression of Channel Feedback Based on Second Order Channel Statistics - A method of variable rate vector quantization reduces the amount of channel state feedback. Channel coefficients of a communication channel are determined and second order statistics (e.g., variances) of the channel taps are computed). Bit allocation for the channel taps are determined based on the coefficients statistics. The channel taps are individually quantized at rates determined based on said bit allocations. | 01-15-2009 |
| 20090069054 | Method and Apparatus for Linearly Precoding Downlink Transmissions to Reduce Temporal Variations in Interference - According to one or more method and apparatus embodiments taught herein, network base stations reduce temporal variations in the interference perceived by mobile stations operating within the network by slowing down the rate at which they change or otherwise update the linear precoding settings applied to their transmitted Orthogonal Frequency Division Multiplex (OFDM) signals in comparison to the rate at which the base stations perform link adaptation. That is, the precoding-related component of measured interference (e.g., other-cell interference) at the mobile stations is made quasi-stationary with respect to channel quality reporting and link adaptation intervals by fixing the preceding settings used by each base station over time intervals substantially longer than the channel reporting/link adaptation intervals. | 03-12-2009 |
| 20090262843 | MIMO Slow Precoding Method and Apparatus - Pre-coder techniques disclosed herein are based on long-term statistical channel information for reducing channel feedback overhead and transmitter complexity. In an embodiment, a receiver includes two or more receive antennas spaced approximately λ/2 apart and a baseband processor. The baseband processor computes channel correlations for different combinations of transmit antennas and each receive antenna and averages the channel correlations over the different receive antennas to form a frequency-independent channel correlation matrix. The baseband processor also computes a scalar representing noise variance at the receive antennas and feeds back the frequency-independent channel correlation matrix and the scalar for use in performing transmitter pre-coding computations. | 10-22-2009 |
| 20100040174 | METHOD AND ARRANGEMENT FOR ESTIMATING DC OFFSET - A method and arrangement for estimating a DC offset for a signal received in a radio receiver. The received signal includes a digitally modulated signal component, a DC offset component, and a noise component. When the signal is of a known type, such as a Gaussian Minimum Shift Keying (GMSK)-modulated signal with constant amplitude in a GSM/EDGE cellular radio system, the method exploits the known characteristics of the statistical distribution for the known type of signal to obtain a better estimate of the DC offset. The statistical distribution of the received digitally modulated signal component is first analyzed. That statistical distribution is then compared to the known statistical distribution for the known type of signal to identify differences. The differences are then used to estimate the DC offset. Additional iterations may be performed to further improve the DC estimate. | 02-18-2010 |
| 20100054322 | CHANNEL ESTIMATION AND EQUALIZATION FOR HARD-LIMITED SIGNALS - The present invention provides a method and apparatus for channel estimation when the amplitude of a received signal is hard-limited. A channel estimator computes amplitude estimates for the received signal based on the phase samples of the received signal and previous channel estimates. The amplitude estimates may comprise the expected values of the amplitude given the phase samples and the initial channel estimates. The channel estimator then computes revised channel estimates based on the amplitude estimates and the phase samples. The process may be performed iteratively to refine the channel estimates during each iteration. | 03-04-2010 |
| 20100128683 | ORTHOGONAL REFERENCE SIGNALS WITH DIFFERENT BANDWIDTH AND OVERLAPPING SPECTRUM - The present invention provides a method of generating mutually orthogonal reference signals for different user terminals in and OFDM system that span different but overlapping subcarriers. The subcarriers allocated to the user terminals are divided into a plurality of non-overlapping subcarrier blocks. Each user terminal is then allocated one or more subcarrier blocks. For each subcarrier block, a user terminal is assigned a reference signal comprising a base reference sequence and a linear phase rotation. To ensure mutual orthogonality among all user terminals, user terminals allocated the same subcarrier block use the same base reference sequence with different linear phase rotations. | 05-27-2010 |
| 20100128824 | BLIND FREQUENCY-OFFSET ESTIMATION FOR TEMPORALLY AND/OR SPATIALLY CORRELATED SIGNAL - An iterative, blind, frequency-offset estimation process that does not require any training signal or demodulated information symbols is disclosed. Receivers embodying the disclosed processes can produce periodic frequency-offset estimates, without running computationally intensive equalization or demodulation algorithms, by exploiting the temporal correlation of the received signal in the time domain, as well as the received signal's correlation across in-phase and quadrature dimensions, in some embodiments, to find a frequency-offset estimate that best fits the received signal in a maximum-likelihood sense. In an exemplary method of estimating receiver frequency offset, a temporally stacked signal block is formed from multi-branch signal samples corresponding to each of two or more time-separated samples of the received signal. The temporally stacked signal block is used in computing a maximum-likelihood joint estimate of the receiver frequency offset and the spatial covariance of the temporally stacked signal block de-rotated by the receiver frequency offset. | 05-27-2010 |
| 20100136940 | SYSTEM AND METHOD OF JOINT SYNCHRONIZATION AND NOISE COVARIANCE ESTIMATION - A system and method in a radio receiver for joint synchronization and noise covariance estimation of a received signal. A spatially and temporally stacked signal model, whereby successive samples of temporally adjacent received signal vectors and corresponding training vectors are stacked, is used in the derivation of the estimation problem. The Toeplitz structure of the channel response matrix is neglected in the formulation of the estimation problem. The resulting estimator jointly estimates a synchronization position, a channel response matrix, and a noise covariance matrix. An estimate of a whitened channel is then computed based on the noise covariance matrix and the estimate of the channel response matrix. | 06-03-2010 |
| 20100167679 | Method and Arrangement for Improved Model Order Selection - In a method of enabling model order selection for joint channel synchronization and noise covariance estimation of at least one received signal in a wireless communication network, generating S | 07-01-2010 |
| 20100234053 | SYSTEMS AND METHOD FOR COORDINATED MULTIPOINT DOWNLINK TRANSMISSIONS - A method for determining antenna weights for use in transmitting data from a plurality of base stations to a user device is disclosed. The antenna weights are determined using an input covariance matrix (S), and the input covariance matrix is determined subject to a predetermined power constraint and a predetermined, non-zero interference constraint. | 09-16-2010 |
| 20100248666 | METHOD AND DEVICE FOR SYNCHRONIZATION AND CHANNEL ESTIMATION IN A RADIO RECEIVER - A device and method in a radio receiver for generating synchronization and channel estimation information based on three parameters consisting of a synchronization position, at least one whitening filter parameter, and a channel estimate. A spatially and temporally stacked signal model is generated by stacking successive samples of temporally adjacent received signal vectors and corresponding training vectors. Initial estimates of a first one or two of the three parameters are then generated based on the spatially and temporally stacked signal model. The rest of the three parameters are then computed based on the initial estimates of the first one or two parameters. If a stopping criterion is met, the method ends and the parameters are used to process the signal. If the stopping criterion is not met, additional iterations are performed to improve the synchronization and estimation information. | 09-30-2010 |
| 20100271931 | CHANNEL STATE INFORMATION RECONSTRUCTION FROM SPARSE DATA - Accurate downlink channel estimates are calculated based on infrequently transmitted Channel State Information (CSI) feedback data from a UE | 10-28-2010 |
| 20100272074 | EFFICIENT UPLINK TRANSMISSION OF CHANNEL STATE INFORMATION - A UE in a wireless communication network transmits succinct, direct channel state information to the network, enabling coordinated multipoint calculations such as joint processing, without substantially increasing uplink overhead. The UE receives and processes reference symbols over a set of non-uniformly spaced sub-carriers, selected according to a scheme synchronized to the network. The frequency response for each selected sub-carrier is estimated conventionally, and the results quantized and transmitted to the network on an uplink control channel. The non-uniform sub-carrier selection may be synchronized to the network in a variety of ways. | 10-28-2010 |
| 20100290382 | DISTRIBUTED COMPUTATION OF PRECODING WEIGHTS FOR COORDINATED MULTIPOINT TRANSMISSION ON THE DOWNLINK - In a Coordinated Multi-point (CoMP) system, the base station (BS) in each serving cell (or sector) is allowed to use not only its own antennas, but also the antennas of neighboring BSs to transmit to mobile terminals in the serving cell to form a floating CoMP cell. The serving BS in each floating CoMP cell computes tentative linear precoding weights for transmissions from the coordinating BSs in the floating CoMP cell to users in the serving cell of the floating CoMP cell. The serving BS determines the power availability for transmit antennas in the floating CoMP cell that are shared with other floating CoMP cells, and scales the tentative precoding weights based on the power availability of the shared transmit antennas to determine final precoding weights so that the power constraints of the shared transmit antennas will not be violated. | 11-18-2010 |
| 20100291936 | EXTENDED COORDINATED MULTIPOINT CELLS TO MITIGATE INTER-COMP-CELL DOWNLINK INTERFERENCE - Inter-CoMP cell interference is reduced by “extending” at least one CoMP cell to include UEs served by a neighboring CoMP cell in the extended CoMP cell's transmission calculations, so as to minimize interference to the UEs served by other CoMP cells. Each UE in a border sub-cell identifies neighboring CoMP cells from which it receives interference in excess of a threshold value, and includes the interfering CoMP cells in a close-neighbor set. The close-neighbor set is transmitted to the UE's serving CoMP cell controller. When downlink transmissions are scheduled to the target UE, the controller notifies the neighboring CoMP cells in the close-neighbor set, identifying the target UE. Those CoMP cells then use information about the channel conditions from their transmit antennas to the target UE receive antennas to compute transmissions to UEs they serve, with the constraint that interference to the target UE is below a predetermined level. | 11-18-2010 |
| 20100317355 | Network-Centric Link Adaptation for Coordinated Multipoint Downlink Transmission - A Coordinated MultiPoint (CoMP) cell controller performs network-centric link adaptation for User Equipment (UE) in the CoMP cell. The CoMP cell controller receives at least infrequent channel estimates from a UE in the CoMP cell, from which it estimates downlink channel and thermal noise at the UE. The CoMP cell controller is aware of the desired signal to be received at the UE, and the intra-CoMP cell interference to the UE caused by transmissions to other UEs in the CoMP cell. The CoMP cell receives from the UE reports of inter-CoMP cell interference caused by transmissions by other CoMP cells. Based on the downlink channel quality, the desired signal, the intra-CoMP cell interference, the inter-CoMP cell interference, and the thermal noise, the CoMP cell controller performs link adaptation by selecting modulation and coding schemes, and other transmission parameters, for an upcoming transmission duration (such as a TTI). | 12-16-2010 |
| 20110064035 | Method and Apparatus for Reducing Multi-User-Interference in a Wireless Communication System - According to the teachings presented herein, each base station in a group of base stations is linked to an associated terminal as a receiver-transmitter pair. These receiver-transmitter pairs reuse channelization resources, such that each terminal represents a source of other-cell interference (also referred to as multi-user interference or MUI) for other terminals in neighboring cells that are reusing all or some of the same channelization resources. Accordingly, the base stations implement a gaming-based algorithm to mitigate MUI for the multiple-input-multiple-output (MIMO) uplink signals received from their associated terminals. More particularly, each base station functions as a player in a game, in which the allowed gaming action is the selection of the precoding matrix to be used for MIMO uplink transmissions to the base station from an associated terminal. | 03-17-2011 |
| 20110080961 | ITERATIVE PRECODER MATRIX COMPUTATION METHOD AND APPARATUS - Precoder weights employed at a base station which coordinates with other base stations to form a super-cell are determined by: (a) determining an initial downlink precoding matrix at the base station for a mobile station serviced by the base station in the super-cell; (b) revising a downlink receiver matrix associated with the mobile station based on the initial downlink precoding matrix; (c) transforming the downlink receiver matrix to an uplink precoder matrix associated with the mobile station; (d) revising an uplink receiver matrix associated with each base station in uplink communication with the mobile station based on the uplink precoder matrix associated with the mobile station; and (e) revising the initial downlink precoding matrix by transforming the uplink receiver matrix to a revised downlink precoding matrix. Steps (b), (c), (d) and (e) are repeated for a particular number of iterations to determine a final downlink precoding matrix for the mobile station. | 04-07-2011 |
