Marvell International Limited

Hsiao-Cheng Tang

Hemanth Sampath

Ravi Narasimhan

Yungping Hsu

Weishi Feng

Guorong Hu

Yonghua Song

King Chun Tsai

George Chien

Donghong Cui

A network device includes a receiver that receives a first signal on a channel. A demodulator outputs demodulated data based on the first signal. A gain device, based on a change in a gain of the first signal, generates a second signal. A validating device determines whether the first signal is a valid direct sequence spread spectrum signal and based on whether the first signal is a valid direct sequence spread spectrum signal, generates a third signal. An assessment device: determines whether the demodulated data includes a predetermined header, where the predetermined header includes a predetermined sequence; determines whether the channel is busy based on the second signal, the third signal, and whether the demodulated data includes the predetermined header with the predetermined sequence; and generates a channel signal indicating whether the channel is busy. A transmitter, based on the channel signal, transmits a fourth signal on the channel.

Method and apparatus for determining whether a channel is busy

A device includes circuitry configured to receive orthogonal frequency-division multiplexing (OFDM) symbols of a training sequence via two or more receive antennas, and circuitry configured to correlate training samples of the OFDM symbols received via the two or more receive antennas to generate a correlation result, estimate a frequency offset using an angle of the correlation result, and correct samples of training symbols in at least one multiple-in-multiple-out (MIMO)-OFDM frame using the frequency offset.

MIMO-OFDM receiver processing

A device includes circuitry configured to receive orthogonal frequency-division multiplexing (OFDM) symbols of a training sequence, and circuitry configured to correlate training samples of the OFDM symbols to determine a frequency offset and configured to provide the determined frequency offset to perform frequency offset compensation for at least one multiple-in-multiple-out (MIMO)-OFDM frame to correct samples of training symbols in the at least one MIMO-OFDM frame. The correlated training samples correspond to a number of receive antennas through which the training sequence was received.

A device can include a module configured to: receive one or more frames, at least one frame including a training sequence; determine a fine frequency offset using the training sequence; and perform frequency offset compensation on the at least one frame using the fine frequency offset.

A physical layer (PHY) packet aggregation technique may be used to reduce the percentage of PHY overhead in data transmission in order to achieve better PHY efficiency and higher throughput. Higher layer packets in an upper layer data queue may be fragmented into appropriate small-size sub-packets, which include a body encapsulated by a MAC header and an FCS field. The sub-packets are then concatenated to form the data field of an aggregated PHY packet. Since each of the sub-packets contains its own MAC (Media Access Control) header and FCS (Frame Check Sequence) field, the receiver can identify and flag erroneous sub-packets on an individual basis. The receiver may transmit a block ACK, which includes the acknowledgement status for each of the sub-packets in the aggregated PHY packet, to the transmitter. The transmitter may resend only the erroneous sub-packet(s).

Technique for reducing physical layer (PHY) overhead in wireless LAN systems

Techniques for and apparatus capable of implementing packet detection and signal recognition in wireless communications systems are disclosed. In particular, the disclosed techniques and apparatus incorporate at least one of relative energy detection operable on assessment of a relative energy threshold for an inbound signal borne across an RF channel, carrier sense operable upon on assessment of at least one of a peak-to-sidelobe ratio and peak-to-peak distance defined by the inbound signal, and comparison operable upon demodulated data corresponding to the inbound signal as compared to predetermined preamble data. Clear channel assessment is performed based on determinations undertaken by one or more of the aforementioned relative energy detection, carrier sense and comparison operations.

Clear channel assessment in wireless communications

A receiver in a MIMO-OFDM system may process OFDM symbols received on a number (M) of receive antennas. The system may utilize a MIMO-OFDM frame format that includes additional long training OFDM symbols, for training additional antennas and for link adaptation, and a header with an additional SIGNAL symbol to indicate MIMO-OFDM-specific information.

MIMO-OFDM receiver processing with frequency and channel estimation

Apparatus, systems, and methods implementing techniques for reducing the variation of a DC offset are described. An input signal is amplified to produce an intermediate signal. The intermediate signal is processed to produce a feedback signal and an output signal, where the output signal has a DC offset that varies with a varying parameter of the circuitry used to process the intermediate signal. Variation of the DC offset of the output signal is reduced using the feedback signal. In one implementation, the circuitry used to process the intermediate signal is a variable-gain amplifier circuit, and the DC offset of the output signal varies with a gain of the variable-gain amplifier.

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Milpitas, CA, United States of America

Hsiao-Cheng Tang