Abstract: Systems and methodologies are described that facilitate mitigating ringing effects of a voltage-controlled oscillator upon turning on a transmitter. A receiver generates at least one frequency offset estimate subsequent to an antecedent frequency offset estimate that is potentially erroneous due to ringing effects. The receiver extrapolates a phase error on upcoming symbols based upon a delta between the subsequent and antecedent frequency offset estimates. The phase error is employed to correct the upcoming symbol for ringing effects. In addition, the transmitter can detect a packet in advance of being ready for transmission and power up upon detection to allow the ringing to settle.

Abstract: An apparatus for wireless communications is provided including a processing system. The processing system is configured to determine path-losses between the apparatus and a plurality of wireless nodes, to group the plurality of wireless nodes into sets based on the determined path-losses, and to exchange data with at least one of the wireless nodes in one of the sets.

Abstract: Embodiments of the present disclosure present methods for calculating beamforming and spatial division multiple access (SDMA) weights utilizing minimum mean square error (MMSE) method. The beamforming and SDMA weights may also be normalized for further performance improvements.

Abstract: Certain aspects of the present disclosure present a technique for designing a signal (SIG) field of a mixed mode preamble transmitted to a plurality of user terminals. The SIG field can signal a number of spatial streams assigned to each user. The SIG field is designed such that a robust interference cancellation can be achieved at each user terminal.

Abstract: 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.

Abstract: 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.

Abstract: 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

Abstract: Embodiments of the present disclosure generally relate to communication, and more specifically to distributed multiple-input multiple-output (MIMO) systems.

Abstract: Methods and apparatus for orthogonal pilot tone mapping in Multiple-In and Multiple-Out (MIMO) and Spatial Division Multiple Access (SDMA) systems are disclosed.

Abstract: 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.

Abstract: Certain embodiments of the present disclosure provide techniques for approximate computation of l2 norms as a part of the maximum likelihood (ML) detection: tri-maxmin, maxsum and sortsum algorithms. The proposed approximation schemes show better accuracy than conventional approximation schemes—the abssum and maxmin algorithms, while the computational complexity is very similar. The error rate performance of the ML detection that utilizes proposed norm-approximation techniques are very close to the reference ML detection with exact calculation of l2 norms, while the computational complexity is significantly smaller.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A modified preamble is used by extended devices that operate in mixed mode environments and green field environments, to accommodate beamforming of transmissions. In one process, an extended wireless device processes data for transmission of that data as a packet, wherein the extended wireless device is a device configured to communicate using a standard protocol understood by each node device and an extended protocol not understood by legacy node devices. If the packet is to be directed at an extended device, the extended wireless device sends a preamble of that packet that is usable in an extended mode at extended devices and usable at a receiving legacy device to determine that the receiving legacy device is not the destination of data to follow the preamble. Once the receiving legacy device is expected to be deferring the network, the extended wireless device can beamform its signal or otherwise vary from the legacy protocol in communications with extended devices.

Abstract: 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.

Abstract: 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.

Abstract: 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).