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公开(公告)号：CA2487358A1
公开(公告)日：2003-12-11
申请号：CA2487358
申请日：2003-06-04
Applicant: QUALCOMM INC
Inventor： FERNANDEZ-CORBATON IVAN JESUS , SMEE JOHN , JAYARAMAN SRIKANT
Abstract: Techniques for selecting either a DFE or an LE for use to equalize a receive d signal, and for quickly and efficiently determining the coefficients for the selected equalizer. In an embodiment, a method is provided whereby the DFE i s initially adapted based on the received signal and a particular adaptive algorithm (e.g., the LMS algorithm) for an initial time period. A quality metric is then determined for an output of the DFE. The DFE is selected for use if the quality metric is better than a threshold value, and the LE is selected otherwise. If the LE is selected, then the initial values for the coefficients of the LE may be derived based on the coefficients of a feed- forward filter and a feedback filter for the DFE, and the LE coefficients ma y further be adapted for an additional time period prior to its use to equaliz e the received signal.
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82.发明专利
公开(公告)号：AU2002331899A1
公开(公告)日：2003-04-07
申请号：AU2002331899
申请日：2002-09-24
Applicant: QUALCOMM INC
Inventor： JAYARAMAN SRIKANT , FERNANDEZ-CORBATON IVAN JESUS , SMEE JOHN E
Abstract: Systems and methods according to the present invention are described for adjusting the number of taps in an adaptive equalizer over time as the rate of change of a communications channel varies. The number of taps or "equalizer length" is adjusted based on an estimate of the Doppler frequency between the devices communicating over a channel. The Doppler frequency is reflective of the rate of change of the communications channel. Greater Doppler frequencies indicate a more quickly varying channel, and vice versa. It is therefore desirable to change the equalizer length (by adding or dropping taps) based on a measurement of the Doppler frequency. Equalizer length is increased as the Doppler frequency decreases. Conversely, equalizer length is decreased as the Doppler frequency increases. This enables the equalizer to achieve a better compromise between the competing goals of adaptation speed (less taps) and ISI reduction (more taps).
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公开(公告)号：AT549792T
公开(公告)日：2012-03-15
申请号：AT02803187
申请日：2002-11-08
Applicant: QUALCOMM INC
Inventor： FERNANDEZ-CORBATON IVAN JESUS , SMEE JOHN , JAYARAMAN SRIKANT
Abstract: A carrier recovery method and apparatus using multiple stages of carrier frequency recovery are disclosed. A receiver uses multiple frequency generation sources to generate carrier signals used to downconvert a received signal. An analog frequency reference having a wide frequency range and coarse frequency resolution is used in conjunction with a digital frequency reference having a narrow frequency range and fine frequency resolution. The multiple carrier signals are multiplied by a received signal to effect a multi-stage downconversion, resulting in a baseband signal. A frequency tracking module measures the residual frequency error present in the baseband signal. The measured residual frequency error is then used to adjust the frequencies of the carrier signals generated by the multiple frequency generation sources.
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公开(公告)号：AT527792T
公开(公告)日：2011-10-15
申请号：AT10175826
申请日：2003-07-18
Applicant: QUALCOMM INC
Inventor： JAYARAMAN SRIKANT , FERNANDEZ-CORBATON IVAN JESUS , SMEE JOHN E
Abstract: A method and apparatus for a decision feedback equalizer wherein a correction term is used to compensate for slicer errors, thus avoiding error propagation. Filter coefficients for the equalizer are selected so as to minimize a cost function for the equalizer, including a correction term as a function of the energy of the filter coefficients. The equalizer includes a coefficient generator responsive to the correction term. One embodiment estimates a transmitted symbol from a received sample as a function of Signal-to-Interference and Noise Ratio (SINR) of the received sample. The received sample is quantized and mapped to a region of a grid overlaid on the transmitted symbol constellation. The region may correspond to a symbol estimate value or may be processed further to obtain a symbol estimate value.
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Patent Agency Ranking
公开(公告)号：NZ577650A
公开(公告)日：2010-09-30
申请号：NZ57765005
申请日：2005-01-20
Applicant: QUALCOMM INC
Inventor： JACOBS PAUL E , BLACK PETER J , JAYARAMAN SRIKANT , GROB MATTHEW S
Abstract: An access network apparatus is disclosed. The access network apparatus includes: a first modulator for modulating a first waveform optimized for unicast transmissions using a first modulation scheme; a broadcast modulator for modulating a second waveform optimized for broadcast transmissions using a second modulation scheme different from the first; and a modulation controller for enabling one of the first modulator and the broadcast modulator as a function of the type of information to be transmitted. An access terminal apparatus is also disclosed. The access terminal apparatus includes: a first demodulator for demodulating unicast transmissions; a broadcast demodulator for demodulating broadcast transmissions; and a modulation controller for enabling one of the first modulator and the broadcast modulator as a function of the type of information received. (62) Divided Out of 571456
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公开(公告)号：PT1658688E
公开(公告)日：2010-09-21
申请号：PT05711606
申请日：2005-01-20
Applicant: QUALCOMM INC
Inventor： JACOBS PAUL E , BLACK PETER J , GROB MATTHEW S , JAYARAMAN SRIKANT
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公开(公告)号：NZ577651A
公开(公告)日：2010-08-27
申请号：NZ57765105
申请日：2005-01-20
Applicant: QUALCOMM INC
Inventor： BLACK PETER J , JAYARAMAN SRIKANT , GROB MATTHEW S , JACOBS PAUL E
Abstract: An apparatus for synchronized broadcast, comprises means for receiving a first transmission slot; means for identifying a portion of the first transmission slot comprising a synchronized broadcast content modulated using a first modulation format having a spreading code common to multiple transmitters and a unicast portion modulated using a second modulation format; means for demodulating the unicast portion; and means for demodulating the broadcast portion. The first and second modulation formats are different. A method for synchronized broadcast is also disclosed. (62) Divided Out of 571456
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89.发明专利
公开(公告)号：AU2005287062C1
公开(公告)日：2010-04-29
申请号：AU2005287062
申请日：2005-09-16
Applicant: QUALCOMM INC
Inventor： JAYARAMAN SRIKANT , XU HAO , BLACK PETER J , NAMGOONG JUNE
Abstract: The present patent application comprises a method and means for demodulating symbols, comprising converting an OFDM symbol from a time domain to a frequency domain, selecting pilot tones, making a soft decision based on received data, and estimating a channel frequency response. In another example, the method and means further comprises selecting guard tones. In another example, the method and means further comprises generating channel estimates for in-band and band-edge pilot tones.
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公开(公告)号：DE602006011871D1
公开(公告)日：2010-03-11
申请号：DE602006011871
申请日：2006-04-26
Applicant: QUALCOMM INC
Inventor： JAYARAMAN SRIKANT , XU HAO , NAMGOONG JUNE , MANGAN MICHAEL JOHN , BLACK PETER J
Abstract: A spread-spectrum communication system provides an effective signal-to-noise ratio (SNR) of received orthogonal frequency division multiplex (OFDM) slots in the presence of timing errors. Effective SNR can serve as a diagnostic tool for determining whether there was a timing error when a measured packet error rate (PER) remains high, and a predicted PER from the effective SNR remains low. A loop can use the effective SNR to control a time reference used by an OFDM decoder.
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