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 |
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 |
20090274237 | BEAMFORMING TECHNIQUES FOR MIMO COMMUNICATION SYSTEMS - Improved beamforming techniques are provided for use in MIMO (multiple-input, multiple-output) communication systems, including MIMO-OFDM systems. The techniques include: (1) determining beamforming (BF) weights using a smoothed singular value decomposition (SVD) of the channel matrix; (2) determining BF weights using a power-optimized minimum mean-square error (MMSE) technique when the number of available transmit antennas exceeds the number of signal streams; and (3) determining BF weights using a hybrid SVD-MMSE technique. Additional techniques for reducing the impulse response length of the BF weights and/or normalizing the power per transmit antenna or per data stream may be used in conjunction with these or other beamforming techniques. | 11-05-2009 |
20090316725 | ENHANCED FRAME AGGREGATION IN A WIRELESS NETWORK SYSTEM - Variable-length information-containing frames (e.g., MPDUs) are aggregated into a bitstream using frame delimiters to distinguish the frames. Aggregation and frame extraction techniques are provided that support recovery from bit errors that may be present in a frame delimiter. One class of techniques involves providing redundant length information in the frame delimiters, e.g., by using multiple copies of a length field or error correction codes usable to correct errors in the length field. The receiver can use the redundant information to detect and correct errors in the length field. Another receiver-side technique iteratively attempts to locate the end of the corresponding frame when a corrupt frame delimiter is detected. Conventional synchronization fields may be eliminated. | 12-24-2009 |
20100061342 | EFFICIENT WIRELESS TRANSMISSION OPPORTUNITY HANDOFF - Circuits, methods, and apparatus that provide high-throughput control fields that, among other functions, provide efficient TXOP handoffs in wireless networks. A handoff may be made by setting one or more bits in a field in a QoS frame, such as the HT control or other appropriate field. Various conditions may be placed on a handoff by a granting station. For example, conditions specifying where a station receiving a TXOP handoff may send data, what the receiving station may do with any remaining TXOP, or what types of data may be transmitted by the receiving station may be imposed. These various conditions may be combined or omitted in any logic combination. | 03-11-2010 |
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 |
20100220661 | PACKET CONCATENATION IN WIRELESS NETWORKS - A wireless network includes a transmitting device and a plurality of receiving devices. The transmitting device is configured to receive a plurality of data packets, including a first data packet and a second data packet, prepare a preamble, prepare a signal field for each of the plurality of data packets, including a first signal field based on the first data packet and a second signal field based on the second data packet, and broadcast the preamble, the first signal field, the first data packet, the second signal field, and the second data packet as a concatenated packet. | 09-02-2010 |
20110026567 | SELF-INTERFERENCE CANCELLATION FOR MULTICHANNEL MODEMS - A method for detecting and reducing aliasing is described. The method may be implemented by a first wireless device. A first signal may be transmitted on a first frequency channel. A second signal may be received on a second frequency channel. The second signal may be received concurrently with the transmission of the first signal. Aliasing of the first signal on the second signal may be detected. Aliasing may be reduced. | 02-03-2011 |
20110082905 | WLAN PEER-TO-PEER GROUP OWNER NEGOTIATION - A method of operating a first wireless device includes sending a first message including a first intent to be a group owner and a value to a second wireless device. In addition, the method includes receiving a second message including a second intent to be the group owner from the second wireless device. Furthermore, the method includes determining which of the first wireless device or the second wireless device should be the group owner based on the first intent, the second intent, and the value. | 04-07-2011 |
20130121243 | SYSTEMS AND METHODS FOR WIRELESS COMMUNICATION OF PACKETS HAVING A PLURALITY OF FORMATS - Systems and methods for communicating packets having a plurality of formats are described herein. In some aspects, a signal (SIG) field in the preamble of a packet may indicate whether an extension field, such as an extension SIG field or SIG-B field, is included in the packet. In another aspect, one or more detectors may be used to auto-detect packets formatted as one of at least two different formats based on a short training field (STF) of a received packet. In some aspects, along training field (LTF) in the preamble of a packet may indicate whether the payload is repetition coded. | 05-16-2013 |
20130121244 | SYSTEMS AND METHODS FOR WIRELESS COMMUNICATION OF PACKETS HAVING A PLURALITY OF FORMATS - Systems and methods for communicating packets having a plurality of formats are described herein. In some aspects, a signal (SIG) field in the preamble of a packet may indicate whether an extension field, such as an extension SIG field or SIG-B field, is included in the packet. In another aspect, one or more detectors may be used to auto-detect packets formatted as one of at least two different formats based on a short training field (STF) of a received packet. In some aspects, along training field (LTF) in the preamble of a packet may indicate whether the payload is repetition coded. | 05-16-2013 |
20130121245 | SYSTEMS AND METHODS FOR WIRELESS COMMUNICATION OF PACKETS HAVING A PLURALITY OF FORMATS - Systems and methods for communicating packets having a plurality of formats are described herein. In some aspects, a signal (SIG) field in the preamble of a packet may indicate whether an extension field, such as an extension SIG field or SIG-B field, is included in the packet. In another aspect, one or more detectors may be used to auto-detect packets formatted as one of at least two different formats based on a short training field (STF) of a received packet. In some aspects, along training field (LTF) in the preamble of a packet may indicate whether the payload is repetition coded. | 05-16-2013 |
20130128806 | SYSTEMS AND METHODS FOR WIRELESS COMMUNICATION OF PACKETS HAVING A PLURALITY OF FORMATS - Systems and methods for communicating packets having a plurality of formats are described herein. In some aspects, a signal (SIG) field in the preamble of a packet may indicate whether an extension field, such as an extension SIG field or SIG-B field, is included in the packet. In another aspect, one or more detectors may be used to auto-detect packets formatted as one of at least two different formats based on a short training field (STF) of a received packet. In some aspects, along training field (LTF) in the preamble of a packet may indicate whether the payload is repetition coded. | 05-23-2013 |
20130155971 | TRANSMITTER CHARACTERISTIC REPRESENTATION FOR TELEVISION WHITE SPACE - A method includes sending, from a wireless device, an information element including at least one transmitter characteristic field. The at least one transmitter characteristic field includes information regarding a spectral mask associated with the wireless device and information regarding an antenna gain associated with the wireless device. | 06-20-2013 |
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 |
20130223357 | GENERATING A SEARCH SET OF TELEVISION WHITE SPACE CHANNELS BASED ON LOCATION INFORMATION - A method includes determining, at an electronic device, information associated with a location of the first electronic device. An initial set of television white space channels is filtered based on the information to generate a search set of television white space channels. A passive scan of the search set of television white space channels is performed at the electronic device to identify a television white space access point. | 08-29-2013 |
20130265907 | Wireless Channelization - A wireless device may be configured to operate in one of two modes where each mode uses a different channel list to perform operations in accordance with the IEEE 802.11 standard. In a first mode, the wireless device operates as an access point that sets up channels using one channel list in order to facilitate communications within a basic service set (BSS). In a second mode, the wireless device uses a second channel list to operate as a station and scan for a BSS. The first channel list contains a subset of the channels contained in the second channel list. The channels in each respective channel list may be reconfigured to adapt to changes in the configuration of a BSS and the devices communicating therein. | 10-10-2013 |