Marvell International Limited

Guorong Hu

Yungping Hsu

Weishi Feng

Hsiao Tang

Hsiao-Cheng Tang

Kevin Hsiao-Cheng Tang

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 circuit includes a multiplexer, a first measurement device, and a decision device. The multiplexer is configured to receive signals from antennas, where the signals include (i) a first signal received from a first antenna of the antennas, and (ii) a second signal received from a second antenna of the antennas. The first measurement device is configured to (i) determine a first peak-to-average ratio based on the first signal, and (ii) determine a second peak-to-average ratio based on the second signal. The decision device is configured to, based on the first peak-to-average ratio and the second peak-to-average ratio, signal the multiplexer to select one of the antennas.

Apparatus and method for selecting antennas based on peak-to-average ratios of received signals

A transceiver including: an antenna configured to a receive a first signal transmitted on a radio frequency channel; and a peak-to-sidelobe ratio determination unit configured to generate a second signal based on a ratio, in which the ratio is based on a peak value and a sidelobe value, and the peak value and the sidelobe value are determined based on a non-correlated version of the first signal. The transceiver further includes a carrier sense unit configured to, based on the second signal, generate a third signal indicating (i) whether the radio frequency channel is busy or (ii) whether the first signal is valid.

Clear channel assessment in wireless communications

A system includes a receiver, a processor and a decision device. The receiver receives a first signal via a first antenna, and one of the first signal and a second signal via a second antenna. The processor determines: based on the first signal as received at the first antenna, a first signal-to-noise ratio (SNR) and a first signal quality value; and based on the one of the first and second signals as received at the second antenna, a second SNR and a second signal quality value. The decision device selects one of the first and second antennas based on (i) a difference between the first SNR and the second SNR if the first SNR is greater than the second SNR, or (ii) the first signal quality value and the second signal quality value if the difference between the first SNR and the second SNR is less than a predetermined threshold.

System and method of selecting antennas based on signal-to-noise ratios and signal quality values

A receiver has a plurality of antennas for receiving a signal. The signal includes a data packet. The receiver includes a correlator to correlate a spreading code with a preamble of the data packet. A first processor determines a signal quality value of the signal at each of the plurality of antennas. The signal quality value at each of the plurality of antennas is determined during the correlation of the spreading code with the preamble of the data packet. A decision unit selects a first antenna of the plurality of antennas for reception of the signal based on the signal quality value determined at each of the plurality of antennas.

Antenna diversity technique for wireless communication

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.

A correlator comprises a plurality of phase rotators, a plurality of combining modules, a plurality of computation modules, and a selection module. The plurality of phase rotators selectively modifies phase for each chip of a first subset of chips by one of M phase offsets, where an incoming symbol comprises the first subset and a second subset of chips, and where M is an integer greater than one. The plurality of combining modules each combine a chip of the first subset with a respective chip of the second subset to generate an output. The plurality of computation modules includes inputs that communicate with the outputs of the plurality of combining modules and produces a plurality of correlator output signals. The selection module chooses one of the plurality of correlator output signals based upon a metric.

Method and apparatus for predicting CCK subsymbols

A receiver includes a demodulator that receives data packets each having a preamble and that generates spreading codewords by correlating a spreading code with the preambles of the data packets. A signal quality device determines signal quality values at a plurality of antennas for each of the data packets after correlation with corresponding ones of the spreading codes and selects one of the plurality of antennas based on the signal quality values. Each of the signal quality values includes a peak-to-average ratio value.

A communication system for communicating data packets includes a receiver subsystem. The receiver subsystem comprises a first antenna, and a second antenna. A direct sequence spread-spectrum demodulator communicates with the first and second antennas. The demodulator is configured to correlate a spreading code with a preamble of each data packet to produce a spreading codeword. The spreading code includes a predetermined number of chips. A signal quality measurement device is responsive to the direct sequence spread-spectrum demodulator. The device is configured to measure signal quality values corresponding to each of the first and second antennas for each data packet after correlation with the spreading code and to select one of said first and second antennas on the basis of the measured signal quality values.

A communication system comprises direct sequence spread-spectrum demodulator that receives first and second signals and that correlates a spreading code with a preamble of each data packet to produce a spreading codeword including a predetermined number of chips. A signal quality measurement device is responsive to the direct sequence spread-spectrum demodulator, measures signal quality values corresponding to each of the first and second signals for each data packet after correlation with the spreading code and that selects one of the first and second signals on the basis of the measured signal quality values.

A method of decoding data includes receiving a symbol and determining a data rate that was used to encode the symbol. A set of correlator output signals are generated based on a first mode when a first data rate was used to encode the symbol and based on a second mode when a second data rate was used to encode the symbol. A maximum-valued signal in one of the set of correlator output signals is identified. The maximum-valued signal in one of the set of correlator output signals is modulated.

Method and apparatus for complementary code keying

An apparatus and a method for symbol decoding of baseband data in a wireless communications network is disclosed, and specifically CCK subsymbol prediction and symbol demodulation that occurs at 5.5 Mbps or 11 Mbps. The apparatus is configured to demodulate or predict the data differently, depending on the modulation rate. If the data was modulated at 11 Mbps, the &#x3c6;rotator is rotated through each of its possible phase values and symbol correlation takes four clock cycles to complete. If the data was modulated at 5.5 Mbps, &#x3c6;is not rotated with a set value of 0 within the correlator architecture, thereby saving power and reducing symbol correlation and subsymbol prediction to a single cycle while in such transmission mode.

An apparatus and a method for decoding data that has been Complementary Code Keying (CCK)-encoded at one of the set of first and second differing data rates. The method includes receiving a symbol, determining which of the first and second data rates was used to encode the symbol and applying the symbol to a first correlator to generate a set of correlator output signals. The first correlator generates the set of correlator output signals based on a first mode when the first data rate was used to encode the symbol and based on a second mode when the second data rate was used to encode the symbol. The method also includes identifying a maximum-valued signal in one of the set of correlator output signals and demodulating the maximum-valued signal in one of the set of correlator output signals.

A method and an apparatus for selecting an antenna from an antenna diversity array in a wireless communication system are provided. The method includes the steps of modulating an incoming signal with a spread-spectrum type modulation, measuring a signal quality value for each antenna in the antenna diversity array, and selecting an antenna from the antenna diversity array on the basis of the measured signal quality values. The step of measuring a signal quality value for each antenna may include computing peak-to-average ratio values by dividing a peak sample value by an average sample value, where the average sample value is determined by averaging all of the predetermined number of sample values for each of the plurality of incoming spreading codewords, and the peak sample value is determined by selecting the maximum of all of the predetermined number of sample values for each of the plurality of incoming spreading codewords.

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Sunnyvale, CA, United States of America

Guorong Hu