| Patent application number | Description | Published |
|---|
| 20080279306 | PILOT TONES IN A MULTI-TRANSMIT OFDM SYSTEM USABLE TO CAPTURE TRANSMITTER DIVERSITY BENEFITS - In a wireless transmitter having a plurality of spatial streams differentiable at a receiver, wherein data is encoded and transmitted over a communication channel with pilot tones to provide the receiver with information about the effects of the communication channel and/or transmitter impairments and/or receiver impairments on the spatial streams transmitted, the benefits can be provided by identifying a plurality of symbol periods within which symbols representing some of the encoded data are to be transmitted, identifying pilot tone values for the plurality of symbol periods, wherein the identified pilot tone values are such that the receiver, when receiving at least some of the pilot tones having the identified pilot tone values, is provided with signals enabling the receiver to characterize the communication channel and/or transmitter impairments and/or receiver impairments to obtain transmit stream diversity gain, and transmitting the symbols and the pilot tones over the plurality of spatial streams for the plurality of symbol periods. In some embodiments, the pilot tones are orthogonal over space and time or over space and time and frequency, while in others they are semi-orthogonal. Pilot tone values might be of a constant amplitude and phase shifted, or might also have amplitude variations wherein at least two pilot tones are nonzero for spatial streams for a given symbol period. | 11-13-2008 |
| 20090060078 | NEAR SOFT-OUTPUT MAXIMUM-LIKELIHOOD DETECTION FOR MULTIPLE-INPUT MULTIPLE-OUTPUT SYSTEMS - Systems and methodologies are described that provide low-complexity soft-output detection for MIMO communication systems. Looping can be performed over a set of constellation points per spatial stream to obtain distance metrics for each of a series of transmitted streams, for which values for the other transmitted streams can be estimated using a MIMO channel matrix and a sub-optimal MIMO algorithm. Examples of MIMO algorithms that can be utilized include Per-Stream List Detection (PSLD), Lattice-Reduced Detection (LRD), and a Guided-M Algorithm. Performance can be further improved by pre-processing the MIMO channel matrix and/or by utilizing techniques for Enhanced Metric Usage (EMU). | 03-05-2009 |
| 20090238299 | Detecting the Number of Transmit Antennas in Wireless Communication Systems - To detect the number of transmit antennas, a fast Fourier transform operation is performed on the received samples of the transmitted long training symbols of a preamble. Next, each of the Fourier transformed results is multiplied with the reference frequency-domain representation of the long training symbol so as to remove the effect of the symbols and to maintain the channel information. Next, inverse Fourier transform or least squares operations is performed on the multiplied values to compute channel impulse response. The number of shifted impulse response in the channel impulse response represents the detected number of transmit antennas. Packets containing preambles of the present invention may be received by extended devices as well as by legacy receivers that are not configured to receive and interpret these preambles. The training symbols may be cyclically-shifted and transmitted on different transmit antennas. | 09-24-2009 |
| 20100008318 | SYSTEMS AND METHODS FOR PROVIDING A SEPARATE CONTENTION WINDOW ALLOWING ALLOCATIONS FOR PENDING UPLINK SDMA TRANSMISSION OPPORTUNITIES - A method for providing uplink spatial division multiple access (SDMA) transmission opportunities (TXOP) is described. A demarcation indication may be sent to one or more subscriber stations. An SDMA contention window may be started. An allocation indication may be received. Requested uplink SDMA TXOP resources may be allocated according to the allocation indication. | 01-14-2010 |
| 20100046542 | MIMO AND SDMA SIGNALING FOR WIRELESS VERY HIGH THROUGHPUT SYSTEMS - Apparatuses for communication are disclosed, including processing systems configured to generate and/or receive a plurality of streams, each of the streams having one or more data packets including a plurality of portions, in which each of the portions in each of the data packets is coded and modulated independently of the other portions in the same data packet, the processing systems being further configured to code and modulate and/or decode and demodulate the data packets. Also disclosed are methods for generating and/or receiving a plurality of streams, each of the streams having one or more data packets comprising a plurality of portions, and for coding and modulating and/or decoding and demodulating each of the portions in each of the data packets independently of the other portions in the same data packet. | 02-25-2010 |
| 20100046656 | PREAMBLE EXTENSIONS - Systems and/or methods for communication that generate a plurality of spatial streams are disclosed. Each of the spatial streams comprises a plurality of symbols. At least a portion of a training sequence is distributed across a first symbol in a first one of the spatial streams and a second symbol in a second one of the spatial streams. | 02-25-2010 |
| 20100061402 | MODIFIED PREAMBLE STRUCTURE FOR IEEE 802.11A EXTENSIONS TO ALLOW FOR COEXISTENCE AND INTEROPERABILITY BETWEEN 802.11A DEVICES AND HIGHER DATA RATE, MIMO OR OTHERWISE EXTENDED DEVICES - A modified preamble is used by extended devices that operate at higher rates, MIMO or other extensions relative to strict 802.11a-compliant devices. The extended devices might use multiple antenna techniques (MIMO), where multiple data streams are multiplexed spatially and/or multi-channel techniques, where an extended transmitter transmits using more than one 802.11a channel at a time. Such extensions to IEEE 802.11a can exist in extended devices. The modified preamble is usable for signaling, to legacy devices as well as extended devices, to indicate capabilities and to cause legacy devices or extended devices to defer to other devices such that the common communication channel is not subject to unnecessary interference. The modified preamble is also usable for obtaining MIMO channel estimates and/or multi-channel estimates. The modified preamble preferably includes properties that facilitate detection of conventional and/or extended modes (“mode detection”) and provides some level of coexistence with legacy IEEE 802.11a devices. | 03-11-2010 |
| 20100091912 | METHODS AND SYSTEMS USING NORM APPROXIMATION FOR MAXIMUM LIKELIHOOD MIMO DECODING - Certain embodiments of the present disclosure provide techniques for approximate computation of l | 04-15-2010 |
| 20100150258 | NEAR SOFT-OUTPUT MAXIMUM LIKELIHOOD DETECTION FOR MULTIPLE-INPUT MULTIPLE-OUTPUT SYSTEMS USING REDUCED LIST DETECTION - A method and apparatus for generating soft-decision output values for a set of transmitted spatial streams in a multiple-input multiple-output (MIMO) communication system are described. The apparatus includes a processor and memory with executable instructions. A plurality of constellation points for respective transmitted spatial streams are looped over to estimate values for other transmitted streams based at least in part on Reduced List Detection (RLD). The plurality of constellation points is a subset of all possible constellation points determined around a spatial stream where more constellation points are assigned to spatial streams with a weaker signal strength than for spatial streams with a stronger signal strength. A set of distance metrics as values of the plurality of constellation points for the respective transmitted spatial streams are determined. Soft-decision outputs for the respective transmitted streams based at least in part on the set of distance metrics are generated. | 06-17-2010 |
| 20100208781 | DISTRIBUTED MIMO - Embodiments of the present disclosure generally relate to communication, and more specifically to distributed multiple-input multiple-output (MIMO) systems. | 08-19-2010 |
| 20100208834 | METHOD AND APPARATUS FOR ORTHOGONAL PILOT TONE MAPPING IN MULTIPLE-IN AND MULTIPLE-OUT (MIMO) AND SPATIAL DIVISION MULTIPLE ACCESS (SDMA) SYSTEMS - Methods and apparatus for orthogonal pilot tone mapping in Multiple-In and Multiple-Out (MIMO) and Spatial Division Multiple Access (SDMA) systems are disclosed. An aspect of the method includes identifying a plurality of symbol periods within which symbols representing encoded data are to be transmitted in a plurality of spatial streams over a communication channel; identifying a plurality of pilot tone values for a plurality of pilot tones in the plurality of symbol periods to create a pilot tone mapping, wherein the identified pilot tone values are such that a receiver, when receiving at least some of the plurality of pilot tones, is provided with signals enabling the receiver to characterize and mitigate any communication impairments, and potentially obtain transmit spatial stream diversity benefits, wherein at least two of the pilot tone values in the pilot tone mapping are orthogonal when the symbols are combined over at least one dimension; and transmitting the symbols and the plurality of pilot tones over the plurality of spatial streams for the plurality of symbol periods. | 08-19-2010 |
| 20100290449 | PREAMBLE EXTENSIONS - Systems and/or methods for communication that generate a plurality of spatial streams are disclosed. Each of the spatial streams comprises a plurality of symbols. At least a portion of a training sequence is distributed across a first symbol in a first one of the spatial streams and a second symbol in a second one of the spatial streams. | 11-18-2010 |
| 20110051636 | FLEXIBLE SDMA AND INTERFERENCE SUPPRESSION - Certain aspects of the present disclosure provide a method for performing interference suppression in spatial division multiple access (SDMA) systems. When the number of receive antennas of a receiver is equal or larger than the number of spatial streams intended for the receiver, the receiver may perform interference suppression on the signals received on all of its antennas. In addition, certain aspects of the present disclosure present a flexible SDMA technique in which a plurality of channel estimates that may be received from an explicit feedback or estimated implicitly, are combined. The combined channel estimate may be used in calculating the SDMA weights. | 03-03-2011 |
