Abstract: Techniques and apparatus for embedding one or more bits of 802.11 Very High Throughput (VHT) information in existing IEEE 802.11 preamble fields are provided. As will be described herein, because different combinations of modulation techniques, coding schemes, and transmission lengths result in the same transmit time (e.g., in terms of symbol length), a clever choice of modulation, coding, and length may allow some extra information to be embedded in a legacy field for use by VHT stations. In this manner, the total VHT preamble transmission time may potentially be reduced, thereby increasing the efficiency of the physical layer (PHY). Moreover, the embedded bits may most likely be invisible to legacy stations, since the transmission time that such stations compute will be independent of these bits by design.

Abstract: A method for estimating a traffic-to-pilot ratio (TPR) for a received signal is disclosed. The received signal is despatialized to obtain a despatialized received signal. A channel matrix is despatialized to obtain a despatialized channel matrix. The despatialized received signal is whitened to obtain a pre-whitened despatialized received signal. The despatialized channel matrix is whitened to obtain a pre-whitened despatialized channel matrix. The estimated TPR for the received signal is determined using the pre-whitened despatialized received signal and one or more pre-whitened despatialized channel estimation coefficients.

Abstract: The present disclosure proposes a method for precoding of transmission signal at an access point of a multiuse system based on eigenmode selection and minimum mean square error (MMSE) processing. The most reliable eigenmodes of every multiple-input multiple-output (MIMO) channel in the system can be selected at each user terminal and corresponding eigenvalues and eigenvectors can be fed back to the access point. The linear MMSE precoding (beamforming) applied at the access point based on the selected eigenmodes may provide an improved transmission capacity performance.

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: An apparatus and method to dynamically schedule user devices in a wireless communication system in single-user multiple-input multiple-output (SU-MIMO) or multiple-user multiple-input multiple-output (MU-MIMO) modes of operation. The dynamic scheduling employs an efficient differential reporting of channel state information that reduces uplink feedback overhead, whereby a base layer value of a channel quality indicator (CQI) is reported in conjunction with a CQI offset value. Antenna subset selection is also reported. The offset value reflects gains by detection with successive interference cancellation if multiple antennas are reported (rank>1), while it reflects the actual offset between single-layer SU-MIMO CQI and MU-MIMO CQI if a single antenna is reported. Scheduled SU-MIMO mode of operation is optimized for a user reporting either a single antenna or multiple antennas, whereas MU-MIMO operation is optimized for a user reporting a single antenna.

Abstract: This disclosure describes techniques for handling transaction timeouts during setup and management of communication sessions. In particular, a communication device may be configured to handle transaction timeouts differently based on the type of signaling and control message that experienced the transaction timeout. In one aspect, the communication devices may handle transaction timeouts experienced during register transactions differently than transaction timeouts experienced during non-register. For example, the communication device that initiated the transaction initiates at least one subsequent transaction to the current proxy server when a non-register transaction experiences the transaction timeout. After experiencing a threshold number of consecutive transaction timeouts, an expiration of a failure duration timer, or a transaction timeout associated with a register transaction, the communication device cancels the current communication session and sends a register message to a new proxy server.

Abstract: A smart antenna system may exploit space diversity by employing an array of antennas whose radiation pattern can be aligned in a direction of arrival (DoA) of a specific signal to be decoded. Smart antennas can be installed on a base station side and/or on a user terminal side. Certain embodiments of the present disclosure provide methods for computationally efficient and accurate searching of the DoA of a specific transmitted signal. The proposed methods utilize Assisted Global Positioning System (A-GPS) coordinates to determine the DoA.

Abstract: Methods and systems for communications that generate a plurality of spatial streams, wherein each of the spatial streams comprises a data packet with a training sequence; and multiply at least a portion of the training sequence in each of the spatial streams with a different spreading sequence. Methods and systems that receive a plurality of spatial streams, wherein each of the spatial streams comprises a data packet with a training sequence; multiply at least a portion of the training sequence in each of the spatial streams with a different spreading sequence; and decode the plurality of spatial streams based on the different spreading sequences.

Abstract: Techniques for scaling symbols to account for large abrupt changes in received power at a user equipment (UE) are described. The UE performs AGC on received samples to obtain input samples. The UE processes (e.g., CDMA demodulates) the input samples to obtain first symbols. The UE determines the power of the input samples and derives a symbol gain based on (e.g., inversely related to) the power of the input samples. The UE scales the first symbols with the symbol gain to obtain detected data symbols having approximately constant amplitude, even with large abrupt changes in the power of the input samples. The UE estimates signal amplitude and noise variance based on the detected data symbols, computes LLRs for code bits of the detected data symbols based on the signal amplitude and noise variance, and decodes the LLRs to obtain decoded data.

Abstract: This disclosure describes techniques for reducing adverse effects of transmit signal leakage in a full-duplex, wireless communication system. The disclosure describes techniques for reducing adverse effects of second order distortion and cross-modulation distortion of transmit signal leakage from a transmitter via a duplexer. The techniques may be effective in rejecting at least a portion of a transmit leakage signal, thereby reducing or eliminating distortion. The adaptive filter may include an estimator circuit that generates a transmit leakage signal estimate. A summer subtracts the estimate from the received signal to cancel transmit leakage and produce an output signal. The estimator circuit generates the transmit leakage signal estimate based on a reference signal and feedback from the output signal. The reference signal approximates the carrier signal used to generate the transmit signal in the transmitter.

Abstract: Techniques to efficiently search for wireless networks while minimizing page loss are described. An available search time that excludes paging periods is determined. A search for cells in wireless networks is performed during the available search time. Pertinent information is obtained for cells acquired during the search. The pertinent information may be dependent on the type of search being performed. For a manual search to find detectable wireless networks, the pertinent information for each acquired cell may be network identifier information. For an automatic search to find higher priority wireless networks, the pertinent information for each acquired cell in a higher priority wireless network may be system information used to select that cell. The search may be suspended prior to a paging period. State information for the search may be saved prior to suspending the search. The search may be resumed using the saved state information at the end of the paging period.

Abstract: A first sequence for a first digital symbol burst is selected to be transmitted, which first sequence comprises a set of end symbols with a first particular symbol pattern. A second sequence for a second digital symbol burst is also selected for transmission after the first digital symbol burst, which second sequence comprises a set of start symbols with a second particular symbol pattern. The first digital symbol burst is modulated in a first modulation format and the second digital symbol burst is modulated in a second modulation format different than the first modulation format. Transmitting the second digital symbol burst starts upon completion of the transmission of the first digital information symbol at an instant so selected that transmission of the end set of bits of the first code sequence is synchronized in time with the start set of bits of the second code sequence.

Abstract: This disclosure describes companded transmit path techniques that may be implemented in a wireless communication device to reduce power consumption and possibly simplify signal modulation. In accordance with this disclosure, in phase (I) and quadrature phase (Q) components of a transmit waveform are compressed at baseband, and an emphasis envelope is generated to represent this compression. The compressed I and Q components are then converted to analog signals and processed. This analog processing may include the mixing process in which the compressed I and Q signals are modulated onto a carrier waveform. The emphasis envelope signal is then used to expand the modulated waveform.

Abstract: In general, this disclosure relates to the establishment of communication sessions between communication devices. In particular, this disclosure describes techniques that provide for quality of service (QoS) aware establishment of communication sessions. As an example, a communication device may attempt to reserve QoS for one or more codecs using a QoS reservation procedure corresponding to the access technology of an access network via which the communication device accesses a core network. The communication device selects one or more codecs to include in a call control message, such a Session Description Protocol (SDP) message, based on the QoS reservation and a QoS mode of the device.

Abstract: A wireless device establishes a data session with a data call, and a data connection is set up for the data session. The wireless device may receive or originate a voice call while the data session is dormant, exchange traffic data for the voice call, and perform handoff between base station controllers (BSCs), if needed, during the voice call. Upon termination of the voice call, the wireless device determines whether it has moved to a new packet zone during the voice call. This may be the case if the wireless device was handed off between BSCs located in different packet zones. If the wireless device has moved to a new packet zone, then the data connection is updated, e.g., by sending to the current serving BSC an origination message indicating no data to send. The network entities perform appropriate actions to update the data connection for the wireless device.

Abstract: This disclosure describes techniques for reducing adverse effects of TX signal leakage in a full-duplex, wireless communication device. The techniques make use of a notch filter to reject TX signal leakage in a signal processed in the RX path of the wireless communication device. The notch filter may be constructed as a complex notch filter using passive resistor and capacitor components to produce a notch frequency that attenuates TX signal leakage components in a desired signal. The notch filter may be applied to a down-converted, baseband signal produced by a passive mixer.

Abstract: Active circuits with active loads linearized via distortion cancellation are described. In one design, an apparatus includes a first stage and a load stage. For an amplifier, the first stage amplifies an input signal and provides an output signal having a larger signal level. For a mixer, the first stage mixes an input signal with an LO signal and provides an output signal. The load stage provides an active load for the first stage and is linearized by canceling distortion generated by the active load. In one design, the load stage includes a first transistor that provides the active load and generates distortion due to its nonlinearity. The load stage further includes at least one transistor that generates a replica of the distortion from the first transistor. The distortion replica is used to cancel the distortion from the first transistor. The first stage may also be linearized with distortion cancellation.

Abstract: Output circuits using pulse width modulation (PWM) and/or pulse density modulation (PDM) are described. In one aspect, a PWM output circuit includes a PWM modulator that operates based on a square wave signal instead of a sawtooth or triangular wave signal. In another aspect, a PDM output circuit includes a PDM modulator that uses variable reference voltages to reduce variations in switching frequency. In yet another aspect, a dual-mode output circuit supports both PWM and PDM and includes a pulse modulator and a class D amplifier. The pulse modulator performs PWM on an input signal if a PWM mode is selected and performs PDM on the input signal if a PDM mode is selected. The class D amplifier receives a driver signal from the pulse modulator and generates an output signal.

Abstract: A mobile station accesses a base station by randomly selecting a first reverse link common control channel from a set of random access channels. The mobile station transmits a request portion of an access probe over the first reverse link common control channel. The request portion is subject to collision with other signals. The request portion comprises a hash identification which is derived from a uniquely identifying number using a hash function. The hash identification quasi-uniquely identifies the mobile station. The mobile station receives a channel assignment message from the base station designating the hash identification and a reserved access channel. The reserved access channel provides communication with a low probability of contention. The mobile station transmits a message portion of the access probe over the reserved access channel.

Abstract: A wireless device achieves good performance using a crystal oscillator that is not compensated for temperature. The crystal oscillator provides a reference signal having a temperature dependent frequency error. A control unit estimates the frequency error (e.g., based on a received pilot) and provides a frequency error estimate. A clock generator generates a digital clock, which tracks chip timing, based on the reference signal and the frequency error estimate. A receiver frequency downconverts an input RF signal with a receive LO signal having the frequency error and provides an analog baseband signal. An ADC digitizes the analog baseband signal based on a sampling clock having the frequency error and provides ADC samples. A re-clocking circuit re-clocks the ADC samples based on a digital clock and provides data samples. A digital rotator frequency translates the data samples based on the frequency error estimate and provides frequency-translated samples centered near DC.