Patents by Inventor Shimman Patel
Shimman Patel has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Publication number: 20080260005Abstract: An apparatus, such as a subscriber unit or a base station within a spread spectrum communication system, provides advanced control over the time-tracking of demodulation elements when unresolvable multipath situations arise. The apparatus provides merge protection that prevents clustered demodulation elements from contracting beyond a minimum time span. In addition, the apparatus provides a master/slave feature for synchronizing the time-tracking of the demodulation elements when clustered around a multipath signal.Type: ApplicationFiled: August 15, 2007Publication date: October 23, 2008Applicant: QUALCOMM INCORPORATEDInventors: Roland R. Rick, Shimman Patel, Keith Saints, Haitao Zhang
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Patent number: 7437172Abstract: Techniques to detect for DTX frames in a “primary” transmission that may be sent in a non-continuous manner using a “secondary” transmission that is sent during periods of no transmission for the primary transmission. The primary and secondary transmissions may be the ones sent on the F-DCCH and Forward Power Control Subchannel, respectively, in an IS-2000 system. In one method, a determination is first made whether or not a frame received for the primary transmission in a particular frame interval is a good frame (e.g., based on CRC). If the received frame is not a good frame, then a determination is next made whether the received frame is a DTX frame or an erased frame based on a number of metrics determined for the primary and secondary transmissions. The metrics may include symbol error rate of the received frame, secondary transmission (e.g., PC bit) energy, and received frame energy.Type: GrantFiled: December 10, 2002Date of Patent: October 14, 2008Assignee: QUALCOMM IncorporatedInventors: Qingxin Chen, Shimman Patel
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Publication number: 20080143580Abstract: Techniques for detecting and suppressing jammers are described. A receiver may perform post-FFT jammer detection and pre-FFT jammer suppression. The receiver may transform an input signal to obtain a frequency-domain signal and may detect for jammers in the input signal based on the frequency-domain signal. The receiver may determine powers of a plurality of carriers based on the frequency-domain signal and may detect for jammers based on peaks in the powers of these carriers. The receiver may filter the input signal (e.g., with a notch filter) to suppress the detected jammers. Alternatively or additionally, the receiver may perform post-FFT jammer detection and post-FFT jammer suppression. The receiver may determine whether jammer is present on each carrier based on data power and channel power for that carrier. The receiver may modify (e.g., zero out or reduce) the frequency-domain signal on carriers with detected jammers.Type: ApplicationFiled: April 25, 2007Publication date: June 19, 2008Inventors: Serguei A. Glazko, James Edward Beckman, Shimman Patel
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Patent number: 7277471Abstract: An apparatus, such as a subscriber unit or a base station within a spread spectrum communication system, provides advanced control over the time-tracking of demodulation elements when unresolvable multipath situations arise. The apparatus provides merge protection that prevents clustered demodulation elements from contracting beyond a minimum time span. In addition, the apparatus provides a master/slave feature for synchronizing the time-tracking of the demodulation elements when clustered around a multipath signal.Type: GrantFiled: September 28, 2001Date of Patent: October 2, 2007Assignee: QUALCOMM IncorporatedInventors: Roland R. Rick, Shimman Patel, Keith Saints, Haitao Zhang
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Publication number: 20070140323Abstract: For frequency bin error estimation, multiple hypotheses are formed for different frequency bin errors, pilot offsets, or combinations of frequency bin error and pilot offset. For each hypothesis, received symbols are extracted from the proper subbands determined by the hypothesis. In one scheme, the extracted received symbols for each hypothesis are despread with a scrambling sequence to obtain despread symbols for that hypothesis. A metric is derived for each hypothesis based on the despread symbols, e.g., by deriving a channel impulse response estimate based on the despread symbols and then deriving the metric based on the channel impulse response estimate. In another scheme, the extracted received symbols for each hypothesis are correlated, and a metric is derived based on the correlation results. For both schemes, the frequency bin error and/or the pilot offset are determined based on the metrics for all hypotheses evaluated.Type: ApplicationFiled: December 20, 2005Publication date: June 21, 2007Inventors: Shimman Patel, Kuei-Chiang Lai, Seguei Glazko
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Publication number: 20070110174Abstract: Techniques for performing time tracking at a receiver are described. A first arriving path (FAP) and a last arriving path (LAP) are detected based on a channel impulse response estimate for a communication channel. The detected FAP and LAP may be correct or swapped. To resolve ambiguity in the detected FAP and LAP, a first hypothesis corresponding to the FAP and LAP being correctly detected and a second hypothesis corresponding to the FAP and LAP being incorrectly detected are evaluated. For each hypothesis, hypothesized FAP and LAP are determined based on the detected FAP and LAP, a correlation window is determined based on the hypothesized FAP and LAP, and correlation is performed using the correlation window. The correct hypothesis is determined based on correlation results for the two hypotheses. The receiver timing is updated based on the hypothesized FAP and LAP for the correct hypothesis and used for demodulation.Type: ApplicationFiled: March 22, 2006Publication date: May 17, 2007Inventors: Serguei Glazko, Kuei-Chiang Lai, Shimman Patel
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Publication number: 20070086329Abstract: Techniques for detecting mode and guard length and estimating timing offset for an OFDM transmission are described. Multiple hypotheses for different combinations of mode and guard length that might have been used for the OFDM transmission are evaluated. For each hypothesis, correlation is performed on received samples for a hypothesized guard interval to obtain correlation results. The energy of the hypothesized guard interval is determined. A first metric is derived based on the correlation results and the energy. The first metric may be filtered, e.g., averaged. Noise is estimated, e.g., based on a set of elements for the filtered first metric at locations determined by an estimated timing offset for the hypothesis. A second metric is derived based on the filtered first metric and the estimated noise. The second metric for all hypotheses may be used to determine the mode, guard length, and timing offset for the OFDM transmission.Type: ApplicationFiled: March 28, 2006Publication date: April 19, 2007Inventors: Serguei Glazko, Jonathan Reeves, Shimman Patel
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Patent number: 7116957Abstract: The velocity of a wireless communications device (106) is estimated. In response to this estimate, a filter bandwidth, such as a pilot filter (310) bandwidth, is adjusted so that the introduction of noise and distortion to a signal received by the device is mitigated. The filter bandwidth is adjusted by increasing it as the estimated velocity increases; and decreasing it as the estimated velocity decreases. Such adjustments may be accomplished through providing a number of predetermined bandwidths that each correspond to a particular velocity range, and setting the filter bandwidth to the predetermined bandwidth that corresponds to the estimated velocity.Type: GrantFiled: October 22, 2001Date of Patent: October 3, 2006Assignee: QUALCOMM IncorporatedInventors: Gilbert Christopher Sih, Andrew Kan, Stein A. Lundby, Shimman Patel
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Patent number: 7039138Abstract: A computationally efficient method and apparatus for estimating the bandwidth of a received signal. In an exemplary implementation, signal power within several selectably narrow frequency bands, each centered about a selected frequency, are calculated using only a relatively small number of arithmetic operations. Applications include using the estimated bandwidth to estimate the relative velocity between the transmitter and receiver, and modifying receiver operation based on such estimate.Type: GrantFiled: July 2, 2001Date of Patent: May 2, 2006Assignee: Qualcomm IncorporatedInventors: Shimman Patel, Thomas B. Wilborn
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Patent number: 6912244Abstract: Techniques to acquire the frequency of a signal instance based on a window of data samples covering a time period shorter than the time needed to achieve frequency lock. The window of data samples is initially captured and stored to a sample buffer. A segment of data samples is then retrieved from the sample buffer for processing. The retrieved data samples are rotated by a current frequency error estimate to provide frequency-translated data samples, which are further processed to provide one or more pilot symbols. An updated frequency error estimate for the frequency-translated data samples is then derived based on the pilot symbols using a frequency control loop. The window of data samples is processed for a number of iterations until frequency acquisition is achieved for the signal instance or termination is reached. For each iteration, one segment is processed at a time and typically in sequential order.Type: GrantFiled: January 30, 2003Date of Patent: June 28, 2005Assignee: Qualcomm Inc.Inventors: Raghu Challa, Mark Charles Roh, Shimman Patel
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Patent number: 6895058Abstract: An efficient system for determining if a paging channel should be received and processed adapted for use a wireless communications device in a wireless communications system employing a quick paging channel. The system includes a first mechanism for receiving an electromagnetic signal having both pilot signal and quick paging signal components. A second mechanism provides one or more initial quality parameters (Epilot1/Îo1,Epilot1) indicative of a quality of a signal environment in which the electromagnetic signal is propagating. The one or more initial quality parameters are based on the pilot signal and are associated with a first symbol of the quick paging signal. A third mechanism ascertains whether a second symbol of the quick paging channel signal or the subsequent paging channel should be processed based on the one or more initial quality parameters and provides a first indication in response thereto.Type: GrantFiled: January 18, 2001Date of Patent: May 17, 2005Assignee: Qualcomm IncorporatedInventors: Farrokh Abrishamkar, Shimman Patel
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Publication number: 20050054366Abstract: Method and apparatus for adjusting the transmission power of base stations in simultaneous communication with a mobile station. The methods described provide for the transmission power of the base stations to be aligned. In the first exemplary embodiment, the transmitters are attached to a separate control unit through communication links. The control unit then derives the most likely command stream and send that to the base stations. In the second exemplary embodiment, the control unit periodically receives the final or average transmit level in a period and an aggregate quality measure for the feedback during a period from each of the transmitters. The control unit determines the aligned power level and transmits a message indicative of the aligned power level to the transmitters.Type: ApplicationFiled: October 18, 2004Publication date: March 10, 2005Inventors: Tao Chen, Jack Holtzman, Leonid Razoumov, Shimman Patel, Keith Saints, Edward Tiedemann
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Publication number: 20050020219Abstract: The velocity of a wireless communications device (106) is estimated. In response to this estimate, a filter bandwidth, such as a pilot filter (310) bandwidth, is adjusted so that the introduction of noise and distortion to a signal received by the device is mitigated. The filter bandwidth is adjusted by increasing it as the estimated velocity increases; and decreasing it as the estimated velocity decreases. Such adjustments may be accomplished through providing a number of predetermined bandwidths that each correspond to a particular velocity range, and setting the filter bandwidth to the predetermined bandwidth that corresponds to the estimated velocity.Type: ApplicationFiled: October 22, 2001Publication date: January 27, 2005Inventors: Gilbert Sih, Andrew Kan, Stein Lundby, Shimman Patel
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Publication number: 20040203463Abstract: Techniques to detect for DTX frames in a “primary” transmission that may be sent in a non-continuous manner using a “secondary” transmission that is sent during periods of no transmission for the primary transmission. The primary and secondary transmissions may be the ones sent on the F-DCCH and Forward Power Control Subchannel, respectively, in an IS-2000 system. In one method, a determination is first made whether or not a frame received for the primary transmission in a particular frame interval is a good frame (e.g., based on CRC). If the received frame is not a good frame, then a determination is next made whether the received frame is a DTX frame or an erased frame based on a number of metrics determined for the primary and secondary transmissions. The metrics may include symbol error rate of the received frame, secondary transmission (e.g., PC bit) energy, and received frame energy.Type: ApplicationFiled: December 10, 2002Publication date: October 14, 2004Inventors: Qingxin Chen, Shimman Patel
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Publication number: 20040165655Abstract: In an antenna diversity environment, the timing offset of the receiver's fingers are based on the timing offset of the received peaks of the base station transmit signals. In a system with non-negligible multipath spacing, the timing offset of the received peaks of the base station transmit signals are not necessarily at the same location. In one embodiment, the demodulating elements for the signal from each base station antenna use the same offset for demodulating and determining an error signal based on pilot signal sampling prior to the timing offset and subsequent to the timing offset. The error signals are averaged and used by a time tracking loop to track the incoming signal. In another embodiment, the demodulating elements for the signal from each base station antenna independently time track the signals with different timing offsets for each finger. The preferred embodiment depends on the method used by the base station to multiplex the data onto multiple transmit antennas.Type: ApplicationFiled: February 26, 2004Publication date: August 26, 2004Inventors: Roland Reinhard Rick, Parvathanathan Subrahmanya, Brian K. Butler, Shimman Patel, Thunyachate Ekvetchavit
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Patent number: 6771692Abstract: In an antenna diversity environment, the timing offset of the receiver's fingers are based on the timing offset of the received peaks of the base station transmit signals. In a system with non-negligible multipath spacing, the timing offset of the received peaks of the base station transmit signals are not necessarily at the same location. In one embodiment, the demodulating elements for the signal from each base station antenna use the same offset for demodulating and determining an error signal based on pilot signal sampling prior to the timing offset and subsequent to the timing offset. The error signals are averaged and used by a time tracking loop to track the incoming signal. In another embodiment, the demodulating elements for the signal from each base station antenna independently time track the signals with different timing offsets for each finger. The preferred embodiment depends on the method used by the base station to multiplex the data onto multiple transmit antennas.Type: GrantFiled: September 25, 2001Date of Patent: August 3, 2004Assignee: Qualcomm IncorporatedInventors: Roland Reinhard Rick, Parvathanathan Subrahmanya, Brian K. Butler, Shimman Patel, Thunyachate Ekvetchavit
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Patent number: 6760362Abstract: A method and apparatus to dynamically adjust parameters of a filter for a pilot signal. An incoming signal containing a pilot signal is filtered using non-identical filters, and the magnitudes of the filtered signals are compared to estimate a bandwidth of the pilot signal. Noise in the incoming signal may also be estimated, preferably from a portion of the incoming signal not expected to contain the pilot signal. Based on the comparison of the filtered signal magnitudes, which may be compensated to remove the noise contribution, the parameters of a filter applied to the incoming signal to isolate the pilot signal are varied. The parameters may vary the bandwidth of a pilot signal filter. The non-identical filters used in the pilot signal bandwidth estimation may be IIR or FIR filters having different passbands, or may be a correlation of the incoming signal with sinusoids of different frequencies.Type: GrantFiled: April 22, 2002Date of Patent: July 6, 2004Assignee: Qualcomm IncorporatedInventors: Shimman Patel, Andrew Kan
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Publication number: 20030198283Abstract: A method and apparatus to dynamically adjust parameters of a filter for a pilot signal. An incoming signal containing a pilot signal is filtered using non-identical filters, and the magnitudes of the filtered signals are compared to estimate a bandwidth of the pilot signal. Noise in the incoming signal may also be estimated, preferably from a portion of the incoming signal not expected to contain the pilot signal. Based on the comparison of the filtered signal magnitudes, which may be compensated to remove the noise contribution, the parameters of a filter applied to the incoming signal to isolate the pilot signal are varied. The parameters may vary the bandwidth of a pilot signal filter. The non-identical filters used in the pilot signal bandwidth estimation may be IIR or FIR filters having different passbands, or may be a correlation of the incoming signal with sinusoids of different frequencies.Type: ApplicationFiled: April 22, 2002Publication date: October 23, 2003Inventors: Shimman Patel, Andrew Kan
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Publication number: 20030176203Abstract: The velocity of a wireless communications device (WCD) (106) is estimated. In response to this estimate a power control command rate is determined. The WCD 106 transmits power control signals to a base station (102) according to the power control command rate. The power control command rate may be determined by mapping the estimated velocity to a velocity range, and selecting a rate that corresponds to the velocity range as the power control command rate. Velocity is estimated by measuring a level crossing rate of a multipath signal.Type: ApplicationFiled: March 12, 2002Publication date: September 18, 2003Inventors: Gilbert Christopher Sih, Shimman Patel, Thunyachate Ekvetchavit
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Publication number: 20030143951Abstract: Techniques to acquire the frequency of a signal instance based on a window of data samples covering a time period shorter than the time needed to achieve frequency lock. The window of data samples is initially captured and stored to a sample buffer. A segment of data samples is then retrieved from the sample buffer for processing. The retrieved data samples are rotated by a current frequency error estimate to provide frequency-translated data samples, which are further processed to provide one or more pilot symbols. An updated frequency error estimate for the frequency-translated data samples is then derived based on the pilot symbols using a frequency control loop. The window of data samples is processed for a number of iterations until frequency acquisition is achieved for the signal instance or termination is reached. For each iteration, one segment is processed at a time and typically in sequential order.Type: ApplicationFiled: January 30, 2003Publication date: July 31, 2003Inventors: Raghu Challa, Mark Charles Roh, Shimman Patel