Patent application number | Description | Published |
20080232484 | METHOD AND APPARATUS FOR IMPROVED ESTIMATION OF SELECTIVE CHANNELS IN AN OFDMA SYSTEM WITH DEDICATED PILOT TONES - The present disclosure provides a method and apparatus of channel estimation for a wireless communication system. Dedicated pilot symbols transmitted over at least one time-frequency region for at least one user are received. Channel parameters are estimated for the at least one time-frequency region based on the received dedicated pilot symbols. | 09-25-2008 |
20080235311 | SIMPLIFIED EQUALIZATION FOR CORRELATED CHANNELS IN OFDMA - Systems and methodologies are described that facilitate equalization of received signals in a wireless communication environment. Multiple transmit and/or receive antennas and utilize MIMO technology to enhance performance. A single tile of transmitted data, including a set of modulation symbols, can be received at multiple receive antennas, resulting in multiple tiles of received modulation symbols. Corresponding modulation symbols from multiple received tiles can be processed as a function of channel and interference estimates to generate a single equalized modulation symbol. Typically, the equalization process is computationally expensive. However, the channels are highly correlated. This correlation is reflected in the channel estimates and can be utilized to reduce complex equalization operations. In particular, a subset of the equalizers can be generated based upon the equalizer function and the remainder can be generated using interpolation. In addition, the equalizer function itself can be simplified. | 09-25-2008 |
20090080508 | FAST SQUARE ROOT ALGORITHM FOR MIMO EQUALIZATION - Systems and methodologies are described that facilitate equalization of received signals in a wireless communication environment. Using multiple transmit and/or receive antennas and MIMO technology, multiple data streams can be transmitted within a single tone. During equalization, receivers can separate data received within a tone into individual data streams. The equalization process generally is computationally expensive. Equalizer functions include the inverse operation, which can be computed using the fast square root method; however, the fast square root method involves large numbers of computations for a set of matrices, where the size of a matrix in the set of matrices increases with the number of transmit or receive antennas. Utilizing a modification of the fast square root method, a subset of the elements of the matrices can be selected and updated to reduce the number and/or complexity of computations. | 03-26-2009 |
20090290661 | DETECTION OF TIME-DOMAIN SEQUENCES SENT ON A SHARED CONTROL CHANNEL - Techniques for sending and receiving signaling messages in a control segment are described. The control segment may be sent with CDM in multiple OFDM symbols. At a receiver, a received sequence is obtained for the control segment. A time-domain signaling sequence is generated based on a signaling message hypothesized to have been sent in the control segment. A correlating sequence is generated based on the signaling sequence. In one design, the signaling sequence is partitioned into multiple sub-sequences, one sub-sequence for each symbol period in which the control segment was sent. Each sub-sequence is cyclically shifted by an amount determined by a channel tap delay. The correlating sequence is then formed by concatenating all of the cyclically shifted sub-sequences. The correlating sequence may also be generated in other manners. The received sequence is correlated with the correlating sequence to determine whether the signaling message was sent in the control segment. | 11-26-2009 |
20090310526 | SYSTEMS AND METHODS OF SIMULTANEOUS, TIME-SHIFTED TRANSMISSION TO MULTIPLE RECEIVERS - Systems and methods for communicating with multiple receivers simultaneously are disclosed. In one embodiment, the method comprises applying a first adjustment to a first signal based on a first propagation path delay between a transmitter and a first receiver, combining the adjusted first signal and a second signal, and transmitting a composite signal based on the combined signal substantially concurrently to the first receiver and a second receiver. | 12-17-2009 |
20100330946 | ENHANCED INTERFERENCE NULLING EQUALIZATION - Systems and methodologies are described that facilitate combining received signals from multiple receive antennas in a wireless communication environment. The received signals from the multiple receive antennas can be weighted utilizing an adaptive combination of maximal ratio combining (MRC) and interference nulling. The combination of MRC and interference nulling can be controlled based upon one or more configurable parameters. For instance, a covariance matrix can be modified to include the one or more configurable parameters, and the modified covariance matrix can be utilized in connection with interference nulling. Further, respective values for the one or more configurable parameters can be selected as a function of at least one input (e.g., measured interference-over-thermal (IoT) value, received loading level indicator, eigenvalue distribution of a covariance matrix, . . . ) related to noise correlation. | 12-30-2010 |
20110019559 | METHODS AND APPARATUS FOR STABILIZING FORWARD LINK MIMO RATE PREDICTION - A method for stabilizing forward link multiple-input and multiple-output (MIMO) rate prediction is described. The forward link channel quality is measured. Instantaneous channel quality estimates are determined for each instantaneous rank. Each instantaneous channel quality estimate provides an instantaneous rate estimate for the instantaneous rank. Rank defines the number of forward link transmission streams and rate defines the total capacity of the forward link for each rank. The instantaneous rates are filtered to determine an average rate per rank. A maximum rate is selected as the maximum over the determined average rate per rank. The instantaneous rank corresponding to the maximum rate is selected as the optimal rank. The instantaneous rate corresponding to the optimal rank is selected as the optimal rate. The optimal rank and optimal rate are then sent to an access point. | 01-27-2011 |
20110059699 | RATE SELECTION FOR A QUASI-ORTHOGONAL COMMUNICATION SYSTEM - A selected rate is received for an apparatus based on a hypothesized signal-to-noise-and-interference ratio (SINR) for the apparatus, and characterized statistics of noise and interference observed at a receiver for the apparatus. Data are processed in accordance with the rate selected for the apparatus. | 03-10-2011 |
20120155425 | PILOT DESIGN FOR IMPROVED CHANNEL AND INTERFERENCE ESTIMATION - Techniques for transmitting pilot and for processing received pilot to obtain channel and interference estimates are described. A terminal may generate pilot symbols for a first cluster in a time frequency block based on a first sequence and may generate pilot symbols for a second cluster in the time frequency block based on a second sequence. The first and second sequences may include common elements arranged in different orders and may be considered as different versions of a single sequence. The terminal may transmit the pilot symbols in their respective clusters. A base station may obtain received pilot symbols from multiple clusters in the time frequency block. The base station may form each of multiple basis vectors with multiple versions of the sequence assigned to the terminal and may process the received pilot symbols with the multiple basis vectors to obtain a channel estimate for the terminal. | 06-21-2012 |