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 |
20110205913 | BEAMFORMING AND SDMA METHODS FOR WIRELESS LAN AND OTHER APPLICATIONS - 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. | 08-25-2011 |
20110216659 | MULTIUSER SCHEDULING IN WLAN SYSTEMS - 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. | 09-08-2011 |
20110299382 | COMMUNICATION DEVICES FOR GENERATING AND USING A MATRIX-MAPPED SEQUENCE - A communication device for generating a matrix-mapped sequence is described. The communication device includes sequence generation circuitry. The communication device also includes mapping circuitry coupled to the sequence generation circuitry. The mapping circuitry applies a first matrix with at least one column multiplied by −1 to a sequence. The communication device also includes a transmit block coupled to the mapping circuitry. | 12-08-2011 |
20110299468 | FORMAT OF VHT-SIG-B AND SERVICE FIELDS IN IEEE 802.11AC - Methods and apparatus for transmitting and receiving frames with various Very High Throughput Signal B (VHT-SIG-B) and Service field formats are provided. Some of these formats may be in accordance with the IEEE 802.11ac amendment to the wireless local area network (WLAN) standard. | 12-08-2011 |
20110310870 | HYBRID TIME AND FREQUENCY DOMAIN CSI FEEDBACK SCHEME - In a downlink multi-user multiple input multiple output (DL MU-MIMO) system, channel state information (CSI) feedback duration may strongly affect media access control (MAC) efficiency. While a time domain compression may give a significant reduction in feedback duration, the time domain compression may have complexity issues at the station (STA). In particular, for time domain compression, a large complex matrix multiplication may be required at the client to estimate a cyclic prefix (CP) length impulse response, which best models the frequency response of the channel. Embodiments of the invention comprise a hybrid scheme that may reduce the above complexity while maintaining significant compression gains. | 12-22-2011 |
20120020261 | METHOD AND APPARATUS FOR ORDERING SUB-FIELDS OF VHT-SIG-A AND VIT-SIG-B FIELDS - Certain aspects of the present disclosure relate to a technique of ordering sub-fields within Signal (SIG) fields of a preamble in Very High Throughput (VHT) wireless communications systems and to a technique of managing sizes of these sub-fields. | 01-26-2012 |
20120033614 | VHT-SIG-B FIELD IN NULL DATA PACKETS (NDPs) - Certain aspects of the present disclosure relate to methods and apparatus for using information in a Very High Throughput Signal B (VHT-SIG-B) field in the preamble of a null data packet (NDP). Retaining the VHT-SIG-B field in NDPs offers several advantages, such as maintaining a unified IEEE 802.11ac preamble structure, providing for 4 μs extra time to process beamforming feedback, and being able to use information in the VHT-SIG-B field to determine a level of interference in the NDP. | 02-09-2012 |
20120039198 | CONSTRUCTING VERY HIGH THROUGHPUT SIGNAL (VHT-SIG) FIELDS FOR REDUCED PEAK-TO-AVERAGE POWER RATIO (PAPR) - Certain aspects of the present disclosure relate to techniques for constructing a VHT-SIG field of a transmission preamble in a manner that may reduce peak-to-average power ratio (PAPR) of the transmission. | 02-16-2012 |
20120058735 | SOUNDING FEEDBACK SCHEMES FOR VERY HIGH THROUGHPUT WIRELESS SYSTEMS - Certain aspects of the present disclosure relate to techniques for transmitting sounding feedback in Very High Throughput (VHT) wireless systems. The sounding feedback may be transmitted from a user station (STA), wherein the feedback may comprise a certain number of beamforming matrices and a certain number of singular values of a wireless channel associated with the STA. Further, the sounding feedback may comprise a bit for indicating whether this feedback represents a Single-User (SU) feedback or a Multi-User (MU) feedback. | 03-08-2012 |
20120063429 | METHODS AND APPARATUS OF FREQUENCY INTERLEAVING FOR 80 MHz TRANSMISSIONS - Certain aspects of the present disclosure provide techniques and apparatus for frequency interleaving for use with 80 MHz transmissions, such as those in the IEEE 802.11ac amendment to the IEEE 802.11 standard. According to certain aspects, frequency interleaving spatial streams for transmissions on channels having widths of about 80 MHz may comprise using an interleaving depth of 26. The number of frequency rotations may be 58 (or 29) for up to four (or up to eight) spatial streams. According to certain aspects, frequency interleaving up to eight (or up to four) spatial streams for transmission on channels having widths of about 80 MHz may comprise performing frequency rotation for each of the spatial streams based on a frequency rotation index=[0 4 2 6 1 5 3 7] (or=[0 2 1 3]). | 03-15-2012 |
20120082193 | BEAMFORMING FEEDBACK OPTIONS FOR MU-MIMO - Beamforming may be used in MIMO communication systems to further enhance spectral efficiency. Beamforming refers to beamed transmissions to a single destination (e.g., a station) at a time, to enhance the rate and/or range of transmission. To perform beamforming from a source to one or more destinations, a channel and/or beamforming matrices corresponding to the channel needs to be known at the source, which may be obtained as feedback from the destination. However, the beamforming matrices may not be smooth over frequency as it is fed back from the destination. Therefore, certain aspects of the present disclosure provide beamforming feedback options, resulting in the smoothness of the channel or a beamforming matrix corresponding to the channel. | 04-05-2012 |
20120140842 | SIGNALING TO PROTECT ADVANCED RECEIVER PERFORMANCE IN WIRELESS LOCAL AREA NETWORKS (LANS) - Certain aspects of the present disclosure relate to techniques that may be used to help control aspects of beamforming by a beamformee. According to certain aspects, a beamformee may be able to signal, to a beamformer, a maximum number of transmit spatial streams to use for single-user beamformed transmissions. | 06-07-2012 |
20120238226 | DATA TRANSMISSION COEXISTENCE USING CONSTANT SYMBOL DURATION WITHIN TELEVISION WHITE SPACE CHANNELS - Methods, systems, and/or devices are provided that permit data transmissions over unused television channels. An unused channel within a television broadcast frequency spectrum is first identified. A downclocked waveform (for data transmission) is then generated by applying a factor to a clock that causes a waveform bandwidth to be reduced from a first bandwidth to a second bandwidth, wherein the second bandwidth of the downclocked waveform is less than a channel bandwidth for the identified unused channel. The downclocked waveform may then be configured so that it coexists with a larger waveform having a third bandwidth that is greater than the channel bandwidth. The downclocked waveform is then wirelessly transmitted from the transmitter device over the identified unused channel. | 09-20-2012 |
20120275376 | CHANNEL STATE INFORMATION FEEDBACK FRAME FORMAT AND FEEDBACK RULES FOR VERY HIGH THROUGHPUT WIRELESS SYSTEMS - Certain aspects of the present disclosure provide techniques and apparatus for generating a unified format of channel state information (CSI) feedback for Very High Throughput (VHT) wireless systems. One example method generally includes generating, at a first apparatus, a frame comprising information relating to SNR if a second apparatus is communicating with the first apparatus using single-user MIMO (SU-MIMO) or multi-user MIMO (MU-MIMO) and transmitting a signal based on the generated frame to the second apparatus. Another example method generally includes generating, at an apparatus, a structure comprising CSI, wherein the CSI includes one of a first matrix with estimates of a channel associated with the apparatus or a second matrix obtained based on singular value decomposition (SVD) of the first matrix and wherein the structure further comprises an indication of which of the first and second matrices is included in the CSI; and transmitting the structure over the channel. | 11-01-2012 |
20120281620 | BEAMFORMING FEEDBACK FORMAT - Certain aspects of the present disclosure propose transmitting a feedback message to an access point. The feedback may comprise a beamforming extension field, which may carry per tone signal to noise ratio of a station. For certain aspects, the station transmitting the per-tone SNR may be a single user (SU)-capable device. For certain aspects, the station may indicate to the access point whether or not it has a maximum likelihood (ML) receiver. | 11-08-2012 |
20120300864 | CHANNEL ESTIMATION BASED ON COMBINED CALIBRATION COEFFICIENTS - Calibration coefficients are combined to provide more robust calibration. In some implementations, calibration coefficients are generated by acquiring two or more sets of calibration coefficients that are associated with different periods of time, different receive devices, or some other condition. These different sets of calibration coefficients are then combined using maximal ratio combining or some other suitable technique. The resulting combined calibration coefficients are used to calibrate implicit channel estimates. | 11-29-2012 |
20120315938 | COMMUNICATION DEVICES FOR MULTIPLE GROUP COMMUNICATIONS - A base station for communicating with multiple groups of wireless communication devices is described. The base station includes a processor and executable instructions stored in memory that is in electronic communication with the processor. The base station determines a number of wireless communication devices. The base station also splits the number of wireless communication devices into groups. The base station further determines a precoding matrix for each group. The base station additionally transmits a beamformed signal to each group using the precoding matrix for each group. | 12-13-2012 |
20130070701 | CHANNEL AND BANDWIDTH SWITCH PROCEDURES FOR WIRELESS NETWORKS - Certain aspects of the present disclosure generally relate to apparatus and methods for switching operating bandwidth and/or operating channel in a wireless communications network. A transmitting STA may send an announcement of a switch to a particular bandwidth in a frame, wherein the presence of absence of a Secondary Channel Offset Element and a Wide Bandwidth Channel Switch Element in the frame indicates whether the particular bandwidth belongs to a first or second set of operating bandwidths. The presence of the Secondary Channel Offset Element and a Wide Bandwidth Channel Switch Element in the frame may indicate a switch to the first set of operating bandwidths. The first set of operating bandwidths may include VHT channels including 80 MHz only, 80+80 MHz and 160 MHz channels. The absence of the Secondary Channel Offset Element and a Wide Bandwidth Channel Switch Element in the frame may indicate a switch to the second set of operating bandwidths. The second set of operating bandwidths may include 20 MHz and 40 MHz channels. | 03-21-2013 |
20130176864 | RATE AND POWER CONTROL SYSTEMS AND METHODS - A method includes transmitting a packet from a first wireless device to a second wireless device, where data within the packet is encoded and a signal representing the packet is modulated in accordance with a modulation and coding scheme (MCS). The method also includes, responsive to receiving an acknowledgement packet that includes a MCS change indicator from the second wireless device via a wireless local area network (WLAN) in response to transmitting the packet, maintaining the MCS when the MCS change indicator has a first value and incrementing the MCS when the MCS has a second value. | 07-11-2013 |
20130176879 | PHASE AND AMPLITUDE TRACKING IN THE PRESENCE OF A WALKING PILOT SIGNAL - A method and apparatus for tracking amplitude and phase of a received low frequency signal comprising a walking pilot signal is disclosed, wherein the pilot signal changes in frequency a number of times according to a sequence that repeats. The design includes initializing a FIFO buffer and summing estimated channel power over the sequence to determine an initial total power. The design also includes, for a new received symbol, determining an updated power estimate for the new received symbol, placing the updated power estimate in the FIFO buffer, and removing a least current value from the FIFO buffer, and estimating amplitude of the signal using a sum of all updated power estimates in the FIFO buffer divided by the initial total power. The design may further include determining a delta phase value using maximum ratio combining scaled with a scaling factor. | 07-11-2013 |
20130177115 | SYSTEMS AND METHODS FOR ADDRESSING DOPPLER EFFECT IN WIRELESS COMMUNICATIONS SYSTEMS - Systems, methods, and devices for performing channel estimates to address the Doppler Effect in wireless communications are described herein. One aspect of the disclosure provides an apparatus for wireless communication. The apparatus comprises a receiver configured to receive coded data tones during a first symbol over a communication channel. The apparatus further comprises a processor. The processor is configured to estimate a common phase offset and amplitude of the communication channel based on pilot tones received over the communication channel. The processor is configured to determine, prior to decoding, a residual phase offset per data tone based on a phase difference between an estimate of the coded data tones and a reference symbol. The processor is configured to estimate update channel state information of the communication channel based on the determined estimated common phase offset, amplitude, and the determined residual phase offset per data tone. | 07-11-2013 |
20130272209 | REQUESTS FOR TRANSMISSION PARAMETERS IN A MULTI-USER SCENARIO - Link adaptation is supported in a multi-user MIMO environment. In some aspects, a frame including a transmission parameter request (e.g., a null data packet announcement (NDPA) including a modulation and coding scheme (MCS) request (MRQ)) specifies multiple destinations. In some aspects, a decision to transmit a frame specifying multiple destinations is based on whether all of destinations support providing feedback to such a frame. In some aspects, transmission parameter feedback (e.g., MCS feedback (MFB)) including channel estimate information is provided in a case where MFB of type MU is requested. | 10-17-2013 |
20130272210 | VERIFYING SUPPORT FOR REQUESTS FOR TRANSMISSION PARAMETERS IN A MULTI-USER SCENARIO - Link adaptation is supported in a multi-user MIMO environment. In some aspects, a frame including a transmission parameter request (e.g., a null data packet announcement (NDPA) including a modulation and coding scheme (MCS) request (MRQ)) specifies multiple destinations. In some aspects, a decision to transmit a frame specifying multiple destinations is based on whether all of destinations support providing feedback to such a frame. In some aspects, transmission parameter feedback (e.g., MCS feedback (MFB)) including channel estimate information is provided in a case where MFB of type MU is requested. | 10-17-2013 |
20130272347 | PROVIDING TRANSMISSION PARAMETERS FOR MULTI-USER COMMUNICATION - Link adaptation is supported in a multi-user MIMO environment. In some aspects, a frame including a transmission parameter request (e.g., a null data packet announcement (NDPA) including a modulation and coding scheme (MCS) request (MRQ)) specifies multiple destinations. In some aspects, a decision to transmit a frame specifying multiple destinations is based on whether all of destinations support providing feedback to such a frame. In some aspects, transmission parameter feedback (e.g., MCS feedback (MFB)) including channel estimate information is provided in a case where MFB of type MU is requested. | 10-17-2013 |
20130322563 | COMMUNICATION DEVICE, METHOD, COMPUTER-PROGRAM PRODUCT AND APPARATUS FOR TRANSMITTING A PILOT SEQUENCE WITH A REDUCED PEAK-TO-AVERAGE POWER RATIO CONTRIBUTION - A communication device for transmitting a pilot sequence is described. The communication device includes pilot generation circuitry configured for generating a pilot sequence with a reduced peak-to-average power ratio contribution after rotation. The communication device also includes transmitter circuitry configured for transmitting the pilot sequence. | 12-05-2013 |
20140003330 | SYSTEMS AND METHODS FOR COMMUNICATION OF SUPPORTED MODULATION CODING SCHEMES | 01-02-2014 |
20140029685 | 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. | 01-30-2014 |
20140064221 | BEAMFORMING FEEDBACK OPTIONS FOR MU-MIMO - Beamforming may be used in MIMO communication systems to further enhance spectral efficiency. Beamforming refers to beamed transmissions to a single destination (e.g., a station) at a time, to enhance the rate and/or range of transmission. To perform beamforming from a source to one or more destinations, a channel and/or beamforming matrices corresponding to the channel needs to be known at the source, which may be obtained as feedback from the destination. However, the beamforming matrices may not be smooth over frequency as it is fed back from the destination. Therefore, certain aspects of the present disclosure provide beamforming feedback options, resulting in the smoothness of a beamforming matrix. | 03-06-2014 |
20140064396 | BEAMFORMING FEEDBACK OPTIONS FOR MU-MIMO - Beamforming may be used in MIMO communication systems to further enhance spectral efficiency. Beamforming refers to beamed transmissions to a single destination (e.g., a station) at a time, to enhance the rate and/or range of transmission. To perform beamforming from a source to one or more destinations, a channel and/or beamforming matrices corresponding to the channel needs to be known at the source, which may be obtained as feedback from the destination. However, the beamforming matrices may not be smooth over frequency as it is fed back from the destination. Therefore, certain aspects of the present disclosure provide beamforming feedback options, resulting in the smoothness of a beamforming matrix. | 03-06-2014 |
20140079048 | PREAMBLE EXTENSIONS - Systems and/or methods for communication generate a plurality of spatial streams. 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. | 03-20-2014 |
20150023335 | PHYSICAL LAYER DESIGN FOR UPLINK (UL) MULTIUSER MULTIPLE-INPUT, MULTIPLE-OUTPUT (MU-MIMO) IN WIRELESS LOCAL AREA NETWORK (WLAN) SYSTEMS - Certain aspects of the present disclosure provide methods and apparatus for uplink (UL) multiuser multiple-input, multiple-output (MU-MIMO) transmissions in a High Efficiency WLAN (HEW) system. One example method generally includes generating a packet having a preamble portion and transmitting the packet. The preamble portion typically includes a long training field (LTF); a first signal (SIG) field subsequent to the LTF; one or more other LTFs located subsequent to the first SIG field; and at least one second SIG field, wherein all SIG fields in the preamble portion, other than the first SIG field, are subsequent to the one or more other LTFs. Another example method generally includes receiving, from an apparatus, a packet having a preamble portion comprising tone-interleaved LTFs; and performing frequency offset adjustment on the packet based on the tone-interleaved LTFs. | 01-22-2015 |
20150063255 | TONE ALLOCATION FOR MULTIPLE ACCESS WIRELESS NETWORKS - A method includes generating a data packet at an access point. The data packet is to be communicated using a waveform that includes a first set of tones that is allocated to a first destination device and a second set of tones that is allocated to a second destination device. The first set of tones is non-overlapping with respect to the second set of tones, and each tone of the first set of tones and each tone of the second set of tones is an orthogonal frequency-division multiple access (OFDMA) tone. The method also includes transmitting the data packet to the first destination device via an institute of electrical and electronics engineers (IEEE) 802.11 wireless network and transmitting the data packet to the second destination device via the IEEE 802.11 wireless network. | 03-05-2015 |