Abstract: In an aspect of the disclosure, an apparatus for wireless communication is provided. The apparatus may include several detectors, each of which may be configured to detect a signal received by a corresponding antenna of several antennas. The apparatus may include a processing system configured to detect a remote apparatus based on outputs from the detectors. The apparatus may include several modem radio frequency chips each including a corresponding detector of the several detectors, and a modem baseband chip including the processing system. The processing system may be configured to allow at most one of the detectors to output a detection declaration to the processing system at a time. The processing system may be configured to send a power-down command to and disconnect from each of the detectors that does not detect the signal from a corresponding antenna of the several antennas.

Abstract: In an aspect of the disclosure, an apparatus for wireless communication is provided. The apparatus may include several detectors, each of which may be configured to detect a signal received by a corresponding antenna of several antennas. The apparatus may include a processing system configured to detect a remote apparatus based on outputs from the detectors. The apparatus may include several modem radio frequency chips each including a corresponding detector of the several detectors, and a modem baseband chip including the processing system. The processing system may be configured to allow at most one of the detectors to output a detection declaration to the processing system at a time. The processing system may be configured to send a power-down command to and disconnect from each of the detectors that does not detect the signal from a corresponding antenna of the several antennas.

Abstract: In an aspect of the disclosure, an apparatus for wireless communication is provided. The apparatus may include several detectors, each of which may be configured to detect a signal received by a corresponding antenna of several antennas. The apparatus may include a processing system configured to detect a remote apparatus based on outputs from the detectors. The apparatus may include several modem radio frequency chips each including a corresponding detector of the several detectors, and a modem baseband chip including the processing system. The processing system may be configured to allow at most one of the detectors to output a detection declaration to the processing system at a time. The processing system may be configured to send a power-down command to and disconnect from each of the detectors that does not detect the signal from a corresponding antenna of the several antennas.

Abstract: A mobile communication device equipped for proximity detection may include a transmitter that emits a periodic ultrasound signal, a receiver that detects the periodic ultrasound signal, an intra-frame filter that filters the detected periodic ultrasound signal based on a frame length of the detected periodic ultrasound signal, and a detector that determines a power level of the filtered periodic ultrasound signal to detect if the receiver is located in an undesirable location.

Abstract: In an aspect of the disclosure, an apparatus for wireless communication is provided. The apparatus may include several detectors, each of which may be configured to detect a signal received by a corresponding antenna of several antennas. The apparatus may include a processing system configured to detect a remote apparatus based on outputs from the detectors. The apparatus may include several modem radio frequency chips each including a corresponding detector of the several detectors, and a modem baseband chip including the processing system. The processing system may be configured to allow at most one of the detectors to output a detection declaration to the processing system at a time. The processing system may be configured to send a power-down command to and disconnect from each of the detectors that does not detect the signal from a corresponding antenna of the several antennas.

Abstract: A mobile communication device equipped for proximity detection may include a transmitter that emits a periodic ultrasound signal, a receiver that detects the periodic ultrasound signal, an intra-frame filter that filters the detected periodic ultrasound signal based on a frame length of the detected periodic ultrasound signal, and a detector that determines a power level of the filtered periodic ultrasound signal to detect if the receiver is located in an undesirable location.

Abstract: A method includes accessing signal data descriptive of a transmission sequence and pre-determined values associated with the transmission sequence. The signal data and the pre-determined values may be stored in a memory. The method includes transmitting a signal from a speaker of an electronic device according to the transmission sequence. The method includes generating a frame based on one or more signals received at a microphone of the electronic device. The one or more signals include an echo signal associated with the transmitted signal. The method includes processing the frame using the pre-determined values to produce an output frame in which a contribution associated with the echo signal is reduced.

Abstract: An acoustic tracking system for determining a position of an object is provided that includes one or more receivers that detect an object based on an acoustic signal transmitted by one or more transmitters. The system also includes a processing component that determines a relative position of the detected object with respect to the one or more receivers and the one or more transmitters and selects at least three pairs of receivers and transmitters. Each selected pair includes a receiver from the one or more receivers and a transmitter from the one or more transmitters. The processing component also determines a position of the detected object using the selected at least three pairs of receivers and transmitters.

Abstract: Wireless receiver circuits and methods include algorithms for switching between a least-squares/minimum mean-square error method of channel estimation known as the CE algorithm, and a continuous plot method of channel estimation known as the CPCE algorithm based upon channel characteristics to improve reception of wireless communications in different reception conditions. In an embodiment, the CPCE algorithm may be selected by a processor for use in channel estimation when a calculated number of candidate paths is less than or equal to a first threshold value, a calculated power ratio of the L strongest paths to the total of all paths is greater than or equal to a second threshold value, and the maximum Automatic Gain Control variation is greater than or equal to a third threshold value. Threshold values may be based on field testing, and set to values at which the CE or CPCE algorithm exhibits better performance.

Abstract: An acoustic tracking system for determining a position of an object is provided that includes one or more receivers that detect an object based on an acoustic signal transmitted by one or more transmitters. The system also includes a processing component that determines a relative position of the detected object with respect to the one or more receivers and the one or more transmitters and selects at least three pairs of receivers and transmitters. Each selected pair includes a receiver from the one or more receivers and a transmitter from the one or more transmitters. The processing component also determines a position of the detected object using the selected at least three pairs of receivers and transmitters.

Abstract: A method includes accessing signal data descriptive of a transmission sequence and pre-determined values associated with the transmission sequence. The signal data and the pre-determined values may be stored in a memory. The method includes transmitting a signal from a speaker of an electronic device according to the transmission sequence. The method includes generating a frame based on one or more signals received at a microphone of the electronic device. The one or more signals include an echo signal associated with the transmitted signal. The method includes processing the frame using the pre-determined values to produce an output frame in which a contribution associated with the echo signal is reduced.

Abstract: Techniques for deriving a channel estimate using a scattered pilot and a continual pilot are described. The scattered pilot is sent on different sets of carriers in different symbol periods. The continual pilot is sent in each symbol period on irregularly spaced carriers. The scattered pilot is used to identify the indices of channel taps of interest, e.g., L strongest channel taps. The continual pilot is used to determine the complex gains of these L channel taps. A receiver derives a channel impulse response estimate based on received pilot symbols for the scattered pilot, identifies the L strongest channel taps, and determines the indices of these L strongest channel taps. The receiver forms a Fourier sub-matrix based on the L tap indices and determines the gains of the L channel taps based on received pilot symbols for the continual pilot and the Fourier sub-matrix.

Abstract: Channel estimation for a wireless Orthogonal Frequency Division Multiplexed (OFDM) link having pilots on at least some carriers in at least some symbols may be implemented by performing first and second channel estimation processes. The first channel estimation process uses only frequency domain interpolation of the pilots to obtain a first candidate channel estimate for the OFDM link, and the second channel estimation process uses both time domain interpolation and frequency domain interpolation of the pilots to obtain a second candidate channel estimate for the OFDM link. One of the first and second candidate channel estimates is selected for processing a communication received via the OFDM link.

Abstract: Wireless receiver circuits and methods include algorithms for switching between a least-squares/minimum mean-square error method of channel estimation known as the CE algorithm, and a continuous plot method of channel estimation known as the CPCE algorithm based upon channel characteristics to improve reception of wireless communications in different reception conditions. In an embodiment, the CPCE algorithm may be selected by a processor for use in channel estimation when a calculated number of candidate paths is less than or equal to a first threshold value, a calculated power ratio of the L strongest paths to the total of all paths is greater than or equal to a second threshold value, and the maximum Automatic Gain Control variation is greater than or equal to a third threshold value. Threshold values may be based on field testing, and set to values at which the CE or CPCE algorithm exhibits better performance.

Abstract: Channel estimation for a wireless Orthogonal Frequency Division Multiplexed (OFDM) link having pilots on at least some carriers in at least some symbols may be implemented by performing first and second channel estimation processes. The first channel estimation process uses only frequency domain interpolation of the pilots to obtain a first candidate channel estimate for the OFDM link, and the second channel estimation process uses both time domain interpolation and frequency domain interpolation of the pilots to obtain a second candidate channel estimate for the OFDM link. One of the first and second candidate channel estimates is selected for processing a communication received via the OFDM link.

Abstract: A method for estimating a size of reverse link resources provided by a base-station transceiver system (BTS), including performing respective first, second, and third measurements of first, second, and third signal strengths received at the BTS. The method also includes comparing the first measurement with the second measurement so as to determine an initial minimum signal strength, and adding at a predetermined time an aging value to the initial minimum signal strength so as to form an updated minimum signal strength. The method further includes forming a comparison between the updated minimum signal strength and the third measurement, determining from the comparison a minimum of the updated minimum signal strength and the third measurement to be a minimum received signal strength, and determining the size of the reverse link resources provided by the BTS in response to the minimum received signal strength.

Abstract: In OFDM communication, a pre-FFT cyclic shift is used to achieve time basis matching among symbols, and/or between symbols and their corresponding channel estimates.

Abstract: A method for estimating a size of reverse link resources provided by a base-station transceiver system (BTS), including performing respective first, second, and third measurements of first, second, and third signal strengths received at the BTS. The method also includes comparing the first measurement with the second measurement so as to determine an initial minimum signal strength, and adding at a predetermined time an aging value to the initial minimum signal strength so as to form an updated minimum signal strength. The method further includes forming a comparison between the updated minimum signal strength and the third measurement, determining from the comparison a minimum of the updated minimum signal strength and the third measurement to be a minimum received signal strength, and determining the size of the reverse link resources provided by the BTS in response to the minimum received signal strength.

Abstract: A method for estimating a size of reverse link resources provided by a base-station transceiver system (BTS), including performing respective first, second, and third measurements of first, second, and third signal strengths received at the BTS. The method also includes comparing the first measurement with the second measurement so as to determine an initial minimum signal strength, and adding at a predetermined time an aging value to the initial minimum signal strength so as to from an updated minimum signal strength. The method further includes forming a comparison between the updated minimum signal strength and the third measurement, determining from the comparison a minimum of the updated minimum signal strength and the third measurement to be a minimum received signal strength, and determining the size of the reverse link resources provided by the BTS in response to the minimum received signal strength.

Abstract: Techniques for deriving a channel estimate using a scattered pilot and a continual pilot are described. The scattered pilot is sent on different sets of carriers in different symbol periods. The continual pilot is sent in each symbol period on irregularly spaced carriers. The scattered pilot is used to identify the indices of channel taps of interest, e.g., L strongest channel taps. The continual pilot is used to determine the complex gains of these L channel taps. A receiver derives a channel impulse response estimate based on received pilot symbols for the scattered pilot, identifies the L strongest channel taps, and determines the indices of these L strongest channel taps. The receiver forms a Fourier sub-matrix based on the L tap indices and determines the gains of the L channel taps based on received pilot symbols for the continual pilot and the Fourier sub-matrix.