Silicon Laboratories Inc.

Other

Wentao Li

Yan Zhou

Hendricus De Ruijter

Terry Lee Dickey

Michael Wu

John M Khoury

Ping Xiong

Guner Arslan

Michael A Wu

Rangakrishnan Srinivasan

Mitchell Reid

Lauri Mikael Hintsala

Güner Arslan

Marius Munder

Bryan Murawski

A technique for adding a new information rate to a legacy physical interface of a communications system includes using a rate switch packet including a distinct rate select start-of-frame delimiter that indicates a newly defined physical interface packet. The rate switch packet uses the same modulation scheme as a base rate packet (e.g., a packet using an information rate defined by a standard communications protocol) and the same preamble pattern as the base rate packet. The preamble length of the rate switch packet can be the same as or different from the preamble length of the base rate packet. An embodiment uses antenna diversity by selecting the antenna in the rate switch packet and using the selected antenna to receive an adjusted rate packet. Additional rate switch start-of-frame delimiters can be used to indicate more than one adjusted rate packet, e.g., to support multiple adjusted information rates.

Method to add additional data rate to legacy physical interface

A demodulator has a correlator bank with multiple correlators. The correlator bank has multiple configurations, including a signal arrival configuration, a coarse timing configuration, and a despreading configuration. The various configurations are used to correlate function transformations of received symbols to template signals. Each correlator has elements with a number of delay blocks corresponding to a number of chips in a symbol. The output of each delay block is multiplied by a bit of a template signal by negating or not negating the output and the multiplications results are summed. A function transformations block receives phase information to generate the function transformations, which are supplied to the correlators. The function transformations include a transformation with a one chip differential, transformations with multi-chip differentials, an average transformation that includes an average of a one-chip phase difference between two adjacent samples, and a second order phase differentiation used for frequency deviation correlation.

Configurable correlator bank for a non-coherent DSSS demodulator

A receiver includes a demodulator having a configurable correlator bank that helps with fast and robust signal detection. The demodulator detects arrival of a first preamble symbol using a first correlator bank configuration. The demodulator makes a course coarse frequency offset estimation after detection of the first preamble signal and the receiver adjusts a frequency used by a mixer based on the coarse frequency offset estimation. The demodulator confirms signal arrival detection with detection of a second preamble symbol. A coarse timing estimation is generated using a second correlator bank configuration using a multi-symbol observation period. A fine frequency offset estimation is made using a third correlation bank configuration. A fine timing estimation is made using a fourth correlation bank configuration. The demodulator then despreads received symbols using a fifth correlator bank configuration.

Non-coherent DSSS demodulator with fast signal arrival detection and improved timing and frequency offset estimation

A wireless communication device has a receiver to listen to a sequence of channels. A controller responds to a preamble being detected on a first channel while the receiver is tuned to the first channel by causing the receiver to stay on the first channel and decode packet(s) associated with the preamble. The controller responds to detection of a first symbol of a first transmission protocol and the preamble not being detected to cause the receiver to stay on the first channel for a predetermined time waiting for a retry. The controller responds to detection of a second symbol of a second transmission protocol and the preamble not being detected to cause the receiver to switch to an advertising channel of the second transmission protocol. If no preambles, noise, or symbols are detected, the receiver switches to listening to a next channel in the sequence after a fixed time.

Concurrent listening

In at least one embodiment, a method for measuring a distance between a first communications device including a first local oscillator and a second communications device including a second local oscillator includes unwrapping N phase values to generate N unwrapped phase values. N is an integer greater than one. Each of the N phase values indicate an instantaneous phase of a received signal. The method includes averaging the N unwrapped phase values to generate an average phase value. The method includes wrapping the average phase value to generate a final phase measurement of the first local oscillator with respect to the second local oscillator.

Phase measurements for high accuracy distance measurements

A receiver concurrently demodulates data transmitted with a plurality of protocols. The receiver utilizes multiple and simultaneous protocol detections at preamble and/or packet payload phases. To provide robust detection and achieve fewer false detections, the receiver extends the cross correlation length once a short cross-correlation is valid. The receiver includes a first demodulator path and a second demodulator path with different filter bandwidths. The second demodulator path includes a decimator that reduces data by two. A correlator bank is coupled to the first and second demodulator paths and concurrently detects preamble symbols associated with a plurality of protocols. A first noise detector is coupled to the first demodulator path and a second noise detector is coupled to the second demodulator path. A first symbol identifier circuit is coupled to the first demodulator path and a second symbol identifier circuit coupled to the second demodulator path to provide packet payload symbol detection.

Context switching demodulator and symbol identifier

An apparatus includes a radio frequency (RF) receiver to receive packets. The RF receiver includes first and second synchronization field detectors (SFDs). The first and second SFDs detect synchronization headers generated using first and second physical layer (PHY) modes, respectively.

Apparatus for radio-frequency receiver with multiple operational modes and associated methods

A method for communicating between a first radio frequency communications device including a first local oscillator and a second radio frequency communications device including a second local oscillator includes generating phase values based on samples of a received signal. Each of the phase values indicates an instantaneous phase of the received signal. The method includes unwrapping the phase values to generate unwrapped phase values. The method includes generating frequency offset estimates based on the unwrapped phase values. The method includes generating an average frequency offset estimate based on the unwrapped phase values. The method includes wrapping the average frequency offset estimate to generate a residual frequency offset estimate. The method includes adjusting the first local oscillator based on the residual frequency offset estimate, thereby reducing a frequency offset between the first local oscillator and the second local oscillator.

Correction of frequency offset between initiator and reflector

A receiver includes a first discrete Fourier transform (DFT) block to perform a first single tone DFT on a positive tone associated with a sounding sequence. A second DFT block performs a second single tone DFT on a negative tone associated with the sounding sequence. A DFT coefficient generation block generates first DFT coefficients based on a nominal frequency of the positive tone and an estimated frequency offset between a transmitter frequency and a receiver frequency. The DFT coefficient generation block generates second DFT coefficients based on a nominal frequency of the negative tone and the estimated frequency offset. Multipliers in the DFT blocks multiply I and Q values of the sounding sequence with the coefficients. Accumulators in the DFT blocks accumulate multiplier outputs. An arctan function receives averaged accumulated values from the first and second DFT blocks and supplies first and second phase values used to calculate fractional timing.

Adjusting DFT coefficients to compensate for frequency offset during a sounding sequence used for fractional time determination

An apparatus comprises an RF receiver for receiving an RF signal. The RF receiver includes front-end circuitry to generate a first down-converted signal, and a plurality of signal detectors to generate a corresponding plurality of detection signals from signals derived from the down-converted signal. The RF receiver further includes a controller to provide at least one control signal to the front-end circuitry based on the plurality of detection signals.

Apparatus for receiver with concurrent detection and associated methods

A mixer in a receiver converts a sounding sequence of alternating ones and zeros to an intermediate frequency signal. A digital mixer converts the intermediate frequency signal to a baseband signal that contains a positive tone and a negative tone. A frequency offset correction circuit generates frequency offset corrections based on frequency offset estimates of the frequency offset between a transmitter of the sounding sequence and the receiver. A frequency adjustment circuit adjusts a frequency of the mixer or the digital mixer to thereby center the positive tone and the negative tone around DC. DFT circuits perform single bin DFTs respectively centered on the positive and negative tones. Phases of the positive and negative tones are calculated based on outputs of the DFT circuits and the phases are used to determine fractional time value associated with a distance measurement between the transmitter and receiver.

Adjusting receiver frequency to compensate for frequency offset during a sounding sequence used for fractional time determination

A method for communicating between a first radio frequency communications device including a first local oscillator and a second radio frequency communications device including a second local oscillator includes receiving a packet using a receiver of the first radio frequency communications device. The method includes detecting an average frequency offset based on sequential samples of the packet. The method includes applying a first adjustment to the first local oscillator to reduce a frequency offset between the first local oscillator and the second local oscillator. The first adjustment is based on the average frequency offset. The method includes, after adjusting the first local oscillator, transmitting a second packet to the second radio frequency communications device by the first radio frequency communications device using the first adjustment and the first local oscillator.

Frequency offset compensation at reflector during frequency compensation interval

A method for operating a radio frequency communications system includes, while operating a first radio frequency communications device in a calibration mode, for each setting of a plurality of settings of a programmable gain amplifier in a receiver of the first radio frequency communications device configured in a zero-intermediate frequency mode of operation, generating an estimate of a DC offset in each of a plurality of digital samples received from an analog circuit path including the programmable gain amplifier, and storing in a corresponding storage element, a compensation value based on the estimate.

DC offset compensation in zero-intermediate frequency mode of a receiver

A system and method for one-way ranging is disclosed. The system comprises a transmitter, also referred to as a tag, transmitting a packet having a sounding sequence. The receiver, also referred to as the locator, receives the sounding sequence. The receiver measures and saves the phase at a plurality of points in time. The sounding sequence has two frequencies, which are additive inverses of one another. A discrete Fourier transform is performed on the plurality of phase measurements to determine the phase of each of the two frequencies. The difference between these two frequencies is related to the time that the packet traveled. Additionally, a calibration of the transmit path and/or receive path may be performed to improve the accuracy of the results.

One way ranging measurement using sounding sequence

A system and method of minimizing interference and retries in an environment where two or more network protocols utilize the same frequency spectrum is disclosed. A lower-power network controller is co-located with a WIFI controller. The lower-power network controller listens for a signature that may indicate the presence of a low power protocol packet, such as BLE or Zigbee. The lower-power controller checks for a waveform that is representative of a Zigbee packet prior to generating a request signal to the WIFI controller. This maximizes the likelihood that no WIFI traffic will occur while the incoming packet is being received.

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Mountain House, CA, United States of America

Wentao Li