Abstract: In a method for synchronizing a receiver to a synchronous signal, a plurality of potential symbols are detected in a signal, the signal having been processed based on automatic gain control (AGC) with a varying gain. Next frame potential symbols corresponding to potential symbols in the plurality of potential symbols are determined, the next frame potential symbols being in frames subsequent to the frames in which the corresponding potential symbols are located. A gain of the AGC is fixed for each corresponding symbol interval during which a next frame potential symbol is operated on by the AGC. In between next frame potential symbols, the AGC is allowed to vary. Next frame potential symbols are analyzed after a transform is calculated to determine if any correspond to a start of a frame.

Abstract: A differential receiver which provides for estimation and tracking of frequency offset, together with compensation for the frequency offset. Estimation and tracking of the frequency offset is undertaken in the phase domain, which reduces computational complexity and allows frequency offset estimation and tracking to be accomplished by sharing already-existing components in the receiver. Compensation for the frequency offset can be performed either in the time domain, before differential detection, or in the phase domain, after demodulation, or can be made programmably selectable, for flexibility.

Abstract: A receiver module includes an automatic gain control module having a gain that varies from a nominal value in response to the receiver module receiving an input signal. The automatic gain control module is configured to generate a first signal in response to the gain settling at a value different from the nominal value. A peak detector module is configured to generate a second signal in response to the gain deviating from the nominal value by a predetermined amount. The peak detector module generates the second signal prior to the automatic gain control module generating the first signal. A control module is configured to receive each of the first signal and the second signal and reset the receiver module to halt processing of the input signal in response to the control module not receiving the first signal within a predetermined amount of time subsequent to the control module receiving the second signal.

Abstract: A system includes a sampling module, a counter module, and a frequency characteristic module. The sampling module samples radio frequency (RF) signals on a first channel for a first predetermined period and a second predetermined period that is subsequent to the first predetermined period. The counter module increments first and second counts when the samples collected during the first and second predetermined periods reverse polarity, respectively. The frequency characteristic module determines a frequency of the RF signal based on at least one of the first and the second counts and determines frequency variation of the RF signal based on the first and second counts.

Abstract: A plurality of beacon data units are generated, and each beacon data unit in the plurality of beacon data units includes an indication that the beacon data unit can be used for transmit beamforming training. The plurality of beacon data units are transmitted via a plurality of antennas during a timeslot reserved for the transmission of beacons. A different beamforming vector is applied to a beamforming network as each beacon data unit is transmitted. In another aspect, a first beamforming training transmission corrupted by a collision is received. A first station to which the first beamforming training transmission corresponds is determined based on the first beamforming training transmission corrupted by the collision. In response to determining the first station, a signal is transmitted to the first station to prompt the first station to transmit a second beamforming training transmission.

Abstract: The present invention provides for receiving a radio frequency signal which encodes transmitted data, and for outputting data corresponding to the transmitted data. The radio frequency signal is received and converted to inphase and quadrature data. Phase information is extracted from the inphase and quadrature data. A symbol timing for the radio signal is determined based on the extracted phase information. The transmitted data encoded within the radio frequency signal is detected and processed based on the determined symbol timing. Data is output based on the detected and processed transmitted data. Since symbol timing is determined based on phase information, in the phase domain, a radio frequency receiver can be constructed with a lower complexity and a simpler structure.

Abstract: In a wireless communication system wherein communication devices exchange information utilizing data units that conform to a first format, wherein the first format includes a short training field (STF) spread with a first spread code and a first cover code, a method is for generating a physical layer (PHY) data unit that conforms to a second format, wherein the PHY data unit is for transmitting PHY information. A first portion of the PHY data unit is generated to indicate the PHY data unit conforms to the second format, wherein the first portion of the PHY data unit includes an STF spread with at least one of a second spread code different than the first spread code or a second cover code different than the first cover code. A second portion of the PHY data unit is generated according to the second format, wherein the second portion of the PHY data unit includes PHY information elements not specified by the first format.

Abstract: In a wireless communication system wherein communication devices exchange information utilizing data units that conform to a first format, a beamforming training (BFT) data unit that conforms to a second format is transmitted, wherein a length of the BFT data unit is shorter than lengths supported by the first format, wherein the BFT data unit is for transmitting PHY beamforming training information. Information to indicate the BFT data unit conforms to the second format is transmitted to a receiving device. The BFT data unit is generated according to the second format, wherein the BFT data unit includes BFT information elements. The BFT data unit is then transmitted to the receiving device.

Abstract: A method for beamforming in a communication system includes receiving a first plurality of training data units via a plurality of antennas, applying a different steering vector as each training data unit is received, generating a first plurality of quality indicators based on the first plurality of received training data units, such that each of the first plurality of quality indicators corresponds to a respective one of the first plurality of received training data units, and selecting a steering vector based on the different steering vectors and the first plurality of quality indicators.

Abstract: Systems and methods are provided for processing a payload portion of a received signal in a single carrier mode or a multiple carrier mode based on a portion of the received signal. A single carrier signaling portion is received at a first rate, and whether the payload portion of the signal is a single carrier signal or a multiple carrier signal is detected from the received single carrier signaling portion. The payload portion of the received signal is received at the first rate and demodulated in a single carrier mode if the detecting determines that the payload portion of the received signal is a single carrier signal, and the payload portion of the received signal is demodulated in a multiple carrier mode if the detecting determines that the payload portion of the received signal is a multiple carrier signal.

Abstract: A system for detecting interference includes an automatic gain control (AGC) module, a peak detection module, and a control module. The AGC module selectively generates a gain-locked signal when an input signal is received. The peak detector module communicates with the AGC module and selectively generates a peak-detect signal. The control module communicates with the AGC module and the peak detector module and generates a control signal when the control module does not receive the gain-locked signal within a predetermined time after receiving the peak-detect signal.

Abstract: A method for generating a preamble of a data unit includes generating a short training field (STF) of the preamble to include one of a repeating series of a sequences or a repeating series of b sequences, such that a and b are complementary sequences, a sum of out-of-phase aperiodic autocorrelation coefficients of a and b is zero, and where the STF is associated with at least synchronization information, and generating a long training field (LTF) of the preamble after the STF to include a? sequences and b? sequences, such that a? is the sequence a cyclically shifted by zero or more positions, b? is the sequence b cyclically shifted by zero or more positions, and where the LTF is associated with channel estimation information.

Abstract: A method for generating a preamble of a data unit for transmission via a communication channel includes generating a first field of the preamble using one of a first sequence or a second sequence, such that the first sequence and the second sequence are complementary sequences such that a sum of out-of-phase aperiodic autocorrelation coefficients of the first sequence and the second sequence is zero; generating, using the other one of the first sequence or the second sequence, an indicator of a start of a second field of the preamble, the second field associated with channel estimation information, such that the indicator of the start of the second field immediately follows the first field; and generating the second field of the preamble.

Abstract: A method of generating a data unit preamble includes generating a first field associated with at least one of packet synchronization information or frame boundary indication, and generating a second field associated with channel estimation, including generating a first channel estimation sequence (CES) symbol and generating a second CES symbol, so that at least one of 1) a sequence in the first field serves as a cyclic prefix of the first CES symbol, 2) a beginning portion of the second CES symbol serves as a cyclic postfix of the first CES symbol, or 3) an ending portion of the first CES symbol serves as a cyclic prefix of the second CES symbol.

Abstract: A system and method of extracting data from data packets transmitted over a wireless network includes receiving a data packet having a preamble portion and a payload portion. The preamble portion is cross correlated with a first known spreading sequence to generate a first timing signal and the preamble portion is cross correlated with a second known spreading signal to generate a frame timing signal. An impulse is detected in the first timing signal and a first timing parameter is set based upon the detected impulse in the first timing signal. An impulse is detected in the frame timing signal and a frame timing parameter is set based upon the detected impulse in the frame timing signal. Data is extracted from the received payload portion according to the first timing parameter and the frame timing parameter.

Abstract: An apparatus includes a signal generator to output one of a first sequence or a second sequence and to augment sequences with cover codes, such that a sum of out-of-phase aperiodic autocorrelation coefficients of the first sequence and the second sequence of is zero, a physical layer preamble controller to control the signal generator to generate a preamble of a data unit, including a short training field (STF) formatter to cause the signal generator to generate an STF for use in at least frame synchronization, and a long training field (LTF) formatter to cause the signal generator to generate an LTF for use in at least channel estimation, such that the STF formatter controls the signal generator to include the first sequence in a last portion of the STF, and the LTF formatter controls the signal generator to include the second sequence in a beginning portion of the LTF.

Abstract: Systems and methods are provided for processing a payload portion of a received signal in a single carrier mode or a multiple carrier mode using a wireless channel receiver based on a portion of the received signal, where a signaling portion of the received signal is a single carrier signal. A single carrier signaling portion is received, and whether the payload portion of the signal is a single carrier signal or a multiple carrier signal is detected from the received single carrier signaling portion. The payload portion of the received signal is demodulated in a single carrier mode if the detecting determines that the payload portion of the received signal is a single carrier signal, and the payload portion of the received signal is demodulated in a multiple carrier mode if the detecting determines that the payload portion of the received signal is a multiple carrier signal. Data from the demodulated payload portion of the received signal is stored in a computer-readable memory.

Abstract: A system for detecting interference includes an automatic gain control (AGC) module, a digital signal processing (DSP) module, and a control module. The AGC module selectively generates a gain-locked signal when an input signal is received. The DSP module communicates with the AGC module and selectively generates a sync-detect signal when the input signal is received. The control module communicates with the AGC module and the DSP module, and generates a control signal when the DSP module does not generate the sync-detect signal within a predetermined time after the AGC module generates the gain-locked signal.

Abstract: A calibration module includes a first input that receives a reference signal, a second input that receives a crosstalk signal, and first and second absolute value modules that generate first and second magnitude signals based on the reference signal and the crosstalk signal, respectively. A first module generates an amplitude correction signal for a quadrature-amplitude modulated (QAM) signal based on the first and second magnitude signals. A second module generates a phase correction signal for the QAM signal based on the reference signal and the crosstalk signal.

Abstract: Orthogonal frequency division multiplexing (OFDM) has been specified by IEEE 802.11a standard as the transmission technique for high-rate wireless local area networks (WLANs). Performance of an OFDM system, however, is heavily degraded by random Wiener phase noise, which causes both common phase error (CPE) and inter-carrier interference (ICI). A method and algorithm is disclosed for efficiently eliminating the effect of phase noise in OFDM based WLANs.