Having Multi-receiver Or Interference Cancellation Patents (Class 375/144)
  • Patent number: 7505510
    Abstract: Reduction of multiple access interference, in one example for asynchronous CDMA systems using long codes. In one aspect, parallel interference cancellation (PIC) implements a decoupled estimate, preferably non-linear and applied at chip intervals. According to another aspect, interference is cancelled using a technique that estimates bits for a symbol by interpolating signature waveforms for users to a common sampling lattice of the received data. According to another aspect, multi-stage, hybrid multi-stage, and reconfigurable recursive multi-stage multi-user detection architectures and corresponding processes are provided.
    Type: Grant
    Filed: February 27, 2006
    Date of Patent: March 17, 2009
    Assignee: The Mitre Corporation
    Inventors: James P. Dunyak, John D. Fite, Jerome M. Shapiro
  • Patent number: 7505538
    Abstract: An ultra-wide band (UWB) waveform receiver with noise cancellation for use in a UWB digital communication system. The UWB receiver uses a two-stage mixing approach to cancel noise and bias in the receiver. Self-jamming is prevented by inverting a portion of the received signal in the first mixer and then coherently detecting the partially and synchronously inverted signal in the second mixer. Since the drive signals on both mixers are not matched to the desired signal, leakage of either drive signal does not jam the desired signal preventing the receiver from detecting and decoding a weak signal.
    Type: Grant
    Filed: January 31, 2005
    Date of Patent: March 17, 2009
    Assignee: Freescale Semiconductor, Inc.
    Inventor: John W. McCorkle
  • Patent number: 7492808
    Abstract: Disclosed is a method for decoding received signals on communication channels between at least one transmit antenna and plural receive antennas in a space-time coded direct sequence (DS)-CDMA communication system. The decoding method includes steps of: adjusting the step-size which is an update unit for the tap weight vector for despreading received signals; updating the tap weight vector using the step-size; and despreading the received signals using the tap weight vector. According to the decoding method, the optimal performance can be achieved because the tap weight vector and the step-size are adaptively updated according to changes of communication environment. Such superior performance is more remarkable as the number of receive antennas and transmit antennas increases.
    Type: Grant
    Filed: April 26, 2005
    Date of Patent: February 17, 2009
    Assignee: Seoul National University Industry Foundation
    Inventors: Jae Hong Lee, Joo Hyun Yi
  • Patent number: 7492809
    Abstract: This invention describes a blind speech user interference cancellation receiver for a high-speed downlink packet access (HSDPA). The key component of the blind SUIC receiver is a joint estimation on hard-decision HSDPA signals and soft-decision interfering speech user (ISU) signals with a full Walsh transform correlator used instead of the conventional RAKER, where the outputs are separated into two parts: the desired HSDPA signal with known spreading codes and the ISU signal with unknown spreading codes. The invention further describes a multistage processing for reaching a targeted convergence rate or a desired bit-error-rate for a received signal involving a hard-decision on the desired HSDPA signal and a soft-decision on the ISU signal.
    Type: Grant
    Filed: August 19, 2003
    Date of Patent: February 17, 2009
    Assignee: Nokia Corporation
    Inventors: Haifeng Wang, Jorma Lilleberg
  • Patent number: 7489747
    Abstract: A decision directed flicker noise canceller for reducing flicker noise in a modulated input signal according to an embodiment of the present invention includes a decision circuit, a conversion circuit, first and second adders and a filter. The decision circuit provides signal decisions based on the input signal. The conversion circuit provides selected signal values based on the signal decisions. The first adder subtracts the selected signal values from signals based on the input signal to provide a flicker noise estimate. The filter receives and filters the flicker noise estimate and the second adder subtracts the filtered flicker noise estimate from the input signal and provides a corrected input signal. In a feedback configuration, the second adder is located in a feedback position before the decision circuit in the signal processing path. In a feed-forward configuration, the second adder is located in a feed-forward position after the decision circuit.
    Type: Grant
    Filed: February 13, 2004
    Date of Patent: February 10, 2009
    Assignee: Xocyst Transfer AG L.L.C.
    Inventors: Mark A. Webster, Alex C. Yeh, Keith R. Baldwin
  • Publication number: 20090028222
    Abstract: A method of cancelling interference induced by a coherent interference source in a spread spectrum receive comprises the steps of: quantifying (44; 94) first interference values induced by the coherent interference source (SCH) in symbols on a first spread spectrum physical channel (P-CCPCH; CPICH); calculating (46, 48, 50; 96, 98, 100) second interference values induced by the coherent interference source in symbols on a second spread spectrum channel (DPCH) from the first interference values; and applying (18; 74) a correction value, derived from the second interference values, to the symbols on the second spread spectrum channel.
    Type: Application
    Filed: February 8, 2006
    Publication date: January 29, 2009
    Applicant: NEC CORPORATION
    Inventors: Mikhail Shnaider, Vasic Dobrica, Holly He, Filip Zalio
  • Patent number: 7480356
    Abstract: A signal-path-selection method in a RAKE receiver includes producing C channel estimates from M received signal paths, determining a plurality of best signal paths using the C produced channel estimates, choosing A signal paths of the plurality of best signal paths in accordance with at least one pre-determined criterion, and combining the A signal paths. C is a measure of channel-estimation capacity of the RAKE receiver. M is greater than C. This Abstract is provided to comply with rules requiring an Abstract that allows a searcher or other reader to quickly ascertain subject matter of the technical disclosure. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).
    Type: Grant
    Filed: December 8, 2004
    Date of Patent: January 20, 2009
    Assignee: Telefonaktiebolaget L M Ericsson (PUBL)
    Inventor: Andres Reial
  • Patent number: 7474688
    Abstract: System and method for detecting multiple direct sequence spread spectrum signals using a multi-mode searcher. A preferred embodiment comprises the specification of a hypothesis for a particular communications network. The hypothesis can then be used to generate a pseudo-random number (PN) sequence that is provided to a searcher. The searcher can then make adjustments to the PN sequence to bring the PN sequence to conformity with requirements of the particular communications network. The adjustment to the PN sequence permits the use of a multi-mode searcher to perform searches for signals of various communications networks with minimal hardware dedicated to each communications network.
    Type: Grant
    Filed: August 28, 2003
    Date of Patent: January 6, 2009
    Assignee: Texas Instruments Incorporated
    Inventors: John G. McDonough, Gibong Jeong, Karim Abdulla, Rajiv R. Nambiar
  • Patent number: 7474691
    Abstract: Reduction of multiple access interference, in one example for asynchronous CDMA systems using long codes. In one aspect, parallel interference cancellation (PIC) implements a decoupled estimate, preferably non-linear and applied at chip intervals. According to another aspect, interference is cancelled using a technique that estimates bits for a symbol by interpolating signature waveforms for users to a common sampling lattice of the received data. According to another aspect, multi-stage, hybrid multi-stage, and reconfigurable recursive multi-stage multi-user detection architectures and corresponding processes are provided.
    Type: Grant
    Filed: February 27, 2006
    Date of Patent: January 6, 2009
    Assignee: The Mitre Corporation
    Inventors: James P. Dunyak, John D. Fite, Jerome M. Shapiro
  • Patent number: 7474692
    Abstract: When once determined to be free of any demodulation error by an interference removing unit provided user by user, a replica signal calculated by the interference removing unit is subtracted from an input signal vector, and a calculated user signal is output as it is as a final user signal. When it is determined by the interference removing unit that there is a demodulation error, the user signal is again calculated by the interference removing unit of an interference canceller of a next stage. As subtraction of the replica signal corresponding to the user signal having a demodulation error from the input signal vector is inhibited, precision of the interference wave removal can be improved.
    Type: Grant
    Filed: November 13, 2006
    Date of Patent: January 6, 2009
    Assignees: National University Corporation Hokkaido University, Sanyo Electric Co., Ltd.
    Inventors: Yasutaka Ogawa, Takeo Ohgane, Toshihiko Nishimura, Masashi Iwami, Jun Kitakado, Yoshiharu Doi
  • Patent number: 7471932
    Abstract: Systems and methods of combining OFDM and CDMA signals are provided. An OFDM packet data channel is overlaid over CDMA transmissions. The channel is scheduled slotwise between multiple users. In some embodiments, there is a CDMA packet data channel which is scheduled together with the OFDM packet data channel.
    Type: Grant
    Filed: August 11, 2004
    Date of Patent: December 30, 2008
    Assignee: Nortel Networks Limited
    Inventors: Shiquan Wu, Wen Tong, Peiying Zhu, Ming Jia, Hua Xu, Daniel Boudreau, Jianming Wu, Mo-Han Fong, Keith Edwards
  • Patent number: 7466743
    Abstract: Information symbols are transmitted simultaneously on independent streams using the same spreading code but from different transmit antennas at the transmitter. These simultaneous data stream could be intended for the same user (and thereby the data rate for any particular user can be increased) or for different users (thereby increasing the system capacity). Each stream of data can belong to a different signal constellation and use a different channel code. At the receiver, a number of receive antennas equal to at least the number of multiple data streams is used to separate the different data streams. We consider two different cases. The first one when no transmit diversity is used (this case can also include the case when transmit diversity with simple antenna weighting is used) and the second when transmit diversity with space-time block coding is used.
    Type: Grant
    Filed: September 12, 2002
    Date of Patent: December 16, 2008
    Assignee: Infineon Technologies AG
    Inventor: Ayman F. Naguib
  • Patent number: 7463609
    Abstract: The receiver includes a Rake receiver for separating a received signal into multipath components, an interference selector for selecting interference symbols corresponding to interfering paths and subchannels, a synthesizer for synthesizing an interference signal from selected paths and estimated subchannel symbols, and a canceller for constructing a projection operator or a scale-invariant subtraction operator to cancel selected interference in multipath components of the received signal, or from the received signal itself. The interference canceller may use a sequence of symbol estimates to simultaneously cancel inter-channel interference and inter-symbol interference. Interference cancellers may be placed at one or more locations within the receiver chain.
    Type: Grant
    Filed: July 29, 2005
    Date of Patent: December 9, 2008
    Assignee: Tensorcomm, Inc
    Inventors: Louis L. Scharf, Vijay Nagarajan
  • Publication number: 20080298437
    Abstract: A communication system performs burst noise cancellation. A transmitter produces and transmits a spread signal that comprises at least one known-value symbol spread by a plurality of non data-carrying orthogonal codes and data symbols spread by at least one data-carrying orthogonal code. The transmitter transmits the spread signal across a communication link that introduces burst noise. A burst noise detector determines burst noise affected chips of the orthogonal codes. A weight computation functional block calculates a plurality of complex-valued combining weights based upon the burst noise affected chips. A vector de-spreader and a linear combiner operate in combination to use the plurality of non data-carrying orthogonal codes, the at least one data-carrying orthogonal code, and the plurality of complex-valued combining weights to de-spread the received spread signal to produce the data symbols with the burst noise substantially removed.
    Type: Application
    Filed: August 12, 2008
    Publication date: December 4, 2008
    Applicant: BROADCOM CORPORATION
    Inventors: BRUCE J. CURRIVAN, NABIL R. YOUSEF, THOMAS J. KOLZE, GOTTFRIED UNGERBOECK
  • Patent number: 7460833
    Abstract: A transmitting apparatus according to the present invention includes a prefilter for compensating a previously measured estimated impulse response of a communication system by assuming a communication system in which the transmitting apparatus and the receiving apparatus are directly connected. The prefilter included in the transmitting apparatus compensates an original characteristic of a communication system. Accordingly, the prefilter enables an accurate channel measurement of a receiving apparatus without any increase of calculation.
    Type: Grant
    Filed: October 21, 2005
    Date of Patent: December 2, 2008
    Assignee: Electronics and Telecommunications Research Institute
    Inventors: Hong-Sup Lee, Hyun-Kyu Chung, Kwang-Chun Lee
  • Publication number: 20080291978
    Abstract: A parametric form of G-Rake and chip equalization for closed-loop transmit diversity is provided, that accounts for impairment correlation between transmit antennas. In a closed-loop transmit diversity system, the base station transmits a signal from two or more antennas, using one of a predetermined set of relative phase offsets at one of the antennas. The parametric estimation of the impairment or data covariance is performed by summing terms, including a term for each possible phase offset. The terms are weighted by fitting parameters. The fitting parameters are jointly solved by fitting the impairment or data covariance estimate to a measured impairment or data covariance. In another aspect, a measured impairment covariance is formed by exploiting a special relationship between the pilot channels of the different transmit antennas.
    Type: Application
    Filed: May 21, 2007
    Publication date: November 27, 2008
    Inventors: Elias Jonsson, Yi-Pin Eric Wang, Gregory E. Bottomley, Stephen J. Grant
  • Publication number: 20080291049
    Abstract: A very narrow band multipoint communication system suitable for use in an automatic meter reading (AMR) system having a communication protocol that divides each main channel of a frequency or digital code hopping system into multiple sub-channels and applies frequency division multiplexing among the sub-channels. Each sub-channel exhibits a very narrow band characteristic that allows gain increase to increases the transmission range of the meters. In addition, frequency division multiplexing among the sub-channels greatly increases the number of meters that can communicate on each main channel. The data collection device demodulates and decodes the multiplexed meter signals at an intermediate frequency with electronic circuitry. The resulting very narrow band AMR system exhibits greater transmission range, greater bandwidth and can accommodate a much larger number of meters per data collection device in comparison to conventional narrow band AMR system.
    Type: Application
    Filed: May 21, 2008
    Publication date: November 27, 2008
    Inventor: Thomas Meek
  • Patent number: 7457367
    Abstract: A detector and method for estimating channel data probability in a multi-user or multiple-input multiple-output communication system includes summing conditional bit probabilities conditioned on hypothetical channel data patterns over stochastically selected hypothetical channel data patterns. Various detailed hardware structures and circuits are also described.
    Type: Grant
    Filed: July 7, 2005
    Date of Patent: November 25, 2008
    Assignee: University of Utah Research Foundation
    Inventors: Behrouz Farhang-Boroujeny, Haidong Zhu, Zhenning Shi, Stephen Andrew Laraway
  • Patent number: 7457347
    Abstract: A method and apparatus for estimating and correcting baseband frequency error in a receiver. In one embodiment, an equalizer performs equalization on a sample data stream and generates filter tap values based on the equalization. An estimated frequency error signal is generated based on at least one of the filter tap values. A rotating phasor is generated based on the estimated frequency error signal. The rotating phasor signal is multiplied with the sample data stream to correct the frequency of the sample data stream. In another embodiment, a channel estimator performs channel estimation and generates Rake receiver finger weights based on at least one of the finger weights. An estimated frequency error signal is generated based on at least one of the finger weights.
    Type: Grant
    Filed: August 22, 2005
    Date of Patent: November 25, 2008
    Assignee: InterDigital Technology Corporation
    Inventors: Philip J. Pietraski, Rui Yang, Mihaela Beluri, Alpaslan Demir
  • Patent number: 7457349
    Abstract: Unassigned finger processors are used to process and measure the arrival times of transmissions from base stations not in the active set. A first set of one or more base stations in active communication with the remote terminal is identified and each base station in the first set is assigned at least one finger processor. A second set of one or more base stations not in active communication with the remote terminal is also identified and an available finger processor is assigned to each of at least one base station in the second set. A (signal arrival) time measurement is then performed for each base station, and outputs indicative of the measurements are provided for further processing.
    Type: Grant
    Filed: December 9, 2003
    Date of Patent: November 25, 2008
    Assignee: QUALCOMM Incorporated
    Inventors: Francesco Grilli, Serge Willenegger
  • Patent number: 7453966
    Abstract: In one aspect thereof this invention provides a method to increase data throughput in an Orthogonal Frequency Division Multiplex (OFDM) wireless communications system. The method includes modeling data throughput as a function of received Signal to Noise Ratio (SNR) with a sigmoid function to produce a throughput curve characterized as having a lower knee region and an upper knee region; and performing a gradient ascent search along the throughput curve by varying the power of a plurality of sub-carriers so as to remove power from any sub-carrier having a received SNR to the left of the lower knee region, and to re-allocate the removed power to sub-carriers having a received SNR to the right of the lower knee region.
    Type: Grant
    Filed: January 12, 2005
    Date of Patent: November 18, 2008
    Assignee: Nokia Corporation
    Inventors: Clive K. Tang, Victor J. Stolpman
  • Patent number: 7447270
    Abstract: The invention relates to a method for controlling the weighting of a data signal in the at least two antenna elements of a multi-element transceiver 1 of a telecommunications network, which data signal is to be transmitted by at least one weighting vector from the transceiver 1 to a terminal 2. For improving such a method, the invention comprises: receiving signals transmitted by the transceiver 1 at the terminal 2; determining for each antenna element a value w(i) indicative of the short term variations; transmitting the values w(i) to the transceiver 1; estimating, based on those values w(i), coefficients e(i) indicative of the stationary structure of the received signals; and weighting the data signal S in the antenna elements with the coefficients e(i). Alternatively, such coefficients e(i) are determined already in the user equipment 2 and transmitted in bursts to the transceiver 1 for controlling the distribution of a data signal to the antenna elements. Similar methods are proposed for soft handover.
    Type: Grant
    Filed: November 17, 2000
    Date of Patent: November 4, 2008
    Assignee: Nokia Corporation
    Inventor: Ari Hottinen
  • Publication number: 20080260002
    Abstract: A wireless communication system and method uses a spatial spreading matrix to distribute the encoded spatial data streams to a number of transmit chains and further uses the spatial spreading matrix for antenna selection computation in a transmitter. The spatial spreading matrix is designed such that a receiver is able to know and utilize the spatial spreading matrix for computing transmission antenna selection, receiver antenna selection and joint transmission/receiving antenna selection. The use of this spatial spreading matrix for antenna selection computation provides increased accuracy in antenna selection for transmission of spatial data streams, where the number of spatial data streams is less than the number of transmit or receive chains between the transmitter and receiver, and the number of transmit or receive chains is less than the corresponding transmission or receiving antennas.
    Type: Application
    Filed: April 18, 2008
    Publication date: October 23, 2008
    Inventors: Hongyuan ZHANG, Rohit U. Nabar
  • Patent number: 7440492
    Abstract: Parallel interference cancellers are connected in successive stages. In each canceller, multiple signal paths are provided for interference replica estimators to receive multiple CDMA channels. A spread code is generated for each signal path for dispreading the path components of the channel. In each signal path, the despread components are RAKE combined and a symbol replica is detected therefrom either by detecting or estimating the type of modulation. The detected symbol replicas are re-modulated and then re-spread to produce interference replicas. In each stage, the interference replicas are summed and subtracted from a delayed CDMA signal and then summed with the interference replicas of the same stage. Output signals from the final stage are despread and symbol replicas are recovered therefrom. For each signal path, a spread code is detected from a control channel and compared to the generated spread code.
    Type: Grant
    Filed: June 28, 2004
    Date of Patent: October 21, 2008
    Assignee: NEC Corporation
    Inventor: Kunifusa Maruyama
  • Publication number: 20080253432
    Abstract: A noise power estimation apparatus is disclosed. The noise power estimation apparatus includes: a part for calculating correlation between a received signal and a pilot signal so as to obtain a received power of the pilot signal for each path; a part for removing a multipath interference component from the received power of the pilot signal by using a predetermined power ratio between the pilot signal and a data signal so as to obtain a corrected received power of the pilot signal; a part for estimating an estimated total power of the pilot signal and the data signal included in the received signal based on the corrected received power and the predetermined power ratio; and a part for subtracting the estimated total power from a total power of the received signal so as to obtain a noise power.
    Type: Application
    Filed: May 8, 2008
    Publication date: October 16, 2008
    Applicant: NTT DoCoMo, Inc.
    Inventors: Junichiro KAWAMOTO, Noriyuki Maeda, Kenichi Higuchi, Mamoru Sawahashi
  • Patent number: 7436876
    Abstract: An ultra wideband system employing a threshold to detect signal quality during acquisition wherein the threshold is adjusted based on signal characteristics such as packet traffic rate, packet loss rate, and packet loss fraction. In one embodiment, the threshold is adjusted by adjusting the gain of a variable gain stage ahead of the threshold. In another embodiment, gain and threshold are adjusted in a coordinated manner wherein gain is adjusted for low signal levels and threshold is adjusted for high signal levels. In one embodiment, packet traffic rate is evaluated over an interval based on maximum packet length, number of monitor packets, and inter-packet delay. In a further embodiment, multiple ramp builders are operated in parallel at multiple code offset values to generate signal statistics to compare with the threshold. Embodiments are disclosed wherein the thresholds are adaptively adjusted based on signal performance characteristics or the multipath environment.
    Type: Grant
    Filed: September 30, 2004
    Date of Patent: October 14, 2008
    Assignee: Time Domain Corporation
    Inventors: Teresa E. Fisher, Jennifer P. Rolin, Irina Dodoukh, Vernon R. Brethour, Mark Roberts, James Richards
  • Patent number: 7433382
    Abstract: A spread spectrum based multichannel modulation Ultra-Wideband (UWB) communication transceiver for indoor wireless operations is presented according to some embodiments. The spread spectrum based multichannels are orthogonal to each other and allow for an operation in parallel. The UWB communication transceiver can also avoid interference with WLAN 802.11a devices in the same environment. In addition, the UWB communication transceiver of the present invention can transmit and receive the scalability chip data rates from 650 Mcps to 7.15 Gcps.
    Type: Grant
    Filed: July 7, 2003
    Date of Patent: October 7, 2008
    Inventor: George J. Miao
  • Patent number: 7433387
    Abstract: A channel estimation method for multiple code-sets in a time-slotted CDMA system. The method includes: A) performing a single code-set channel estimation of the received signal of each code-set, respectively, to obtain an original channel estimation, and deciding whether the desired number of iterations is reached; if yes, outputting each single code-set channel estimate; otherwise, going to Step B; B) performing limited time decision for the original channel estimates, retaining taps of channel estimation that meet a certain condition, recovering the interference caused by the response of each code-set using the tap values; canceling the interference caused by the response of other code-sets in the received signal of each code-set to obtain a clean signal of each code-set; taking the clean signal of each code-set as the said received signal of each code-set; and returning to Step A.
    Type: Grant
    Filed: July 14, 2005
    Date of Patent: October 7, 2008
    Assignee: Da Tang Mobile Communications Equipment Co., Ltd.
    Inventors: Yingmin Wang, Shiyan Ren
  • Patent number: 7430233
    Abstract: A spread-spectrum demodulator includes a spreading code generating section, correlation value computing section, data signal demodulating section, peak signal detecting section, and spreading code generation control section. The spreading code generating section generates a spreading code for correlating with a received spread signal. The correlation value computing section computes a correlation value between the spread signal and the spreading code output from the spreading code generating section. The data signal demodulating section detects the peak of an output from the correlation value computing section and demodulates a data signal on the basis of the detected peak. The peak signal detecting section detects the peak of the output from the correlation value computing section. The spreading code generation control section changes the shifting direction of the spreading code relative to the spread signal every time a peak is detected by the peak signal detecting section.
    Type: Grant
    Filed: December 2, 2003
    Date of Patent: September 30, 2008
    Assignee: Nippon Telephone and Telegraph Corporation
    Inventors: Kenji Suzuki, Mamoru Ugajin, Tsuneo Tsukahara
  • Publication number: 20080232327
    Abstract: here is provided a new multi-user receiver configuration technique which solves the problems of the user signal separation function of the multi-user receiver such as the interference canceller, decorrelator, and least square error detection. That is, there is provided a code-division multiplex signal decorrelation/identification method for realizing much more excellent performance than the aforementioned methods in the aspect of the power band amplitude product required for one-bit transfer as the evaluation reference of the CDMA method. A function for successively judging the best user is added to the conventional least square error detector MMSE-D shown by a dotted line in the block diagram of the successive detection type least square error detection method (SD-MMSE).
    Type: Application
    Filed: March 10, 2005
    Publication date: September 25, 2008
    Inventors: Noriyoshi Kuroyanagi, Naoki Suehiro, Kohei Otake, Shinya Matsufuji, Satoru Ozawa, Mitsuhiro Tomita
  • Patent number: 7428261
    Abstract: Interference cancellation techniques for use in a wireless multicarrier communications system where signals from multiple wireless networks might be present and interfering with the detection and demodulation processes are disclosed. Interference cancellation is applied to the interfering network before removing same-system interference. By removing the contribution of all interfering systems' from a receiver's aggregate signal, the receiver is capable of detection and demodulation. Performance can be further improved by including an additional level of interference cancellation within the system of interest to separate the individual user of interest.
    Type: Grant
    Filed: June 30, 2003
    Date of Patent: September 23, 2008
    Assignee: Bae Systems Information and Electronic Systems Integration Inc.
    Inventors: Diane G. Mills, Michael J. Kotrlik, Kari M. Karwedsky
  • Patent number: 7428262
    Abstract: A method and apparatus for channel estimation in a rake receiver of a CDMA communication system operates with a finite-impulse-response channel estimation filter with L taps and having a fixed delay. A pilot sequence of a received sequence of data from a channel of the communication system on the rake receiver is input. A quality of the channel of the communication system is determined using noise or Doppler measurements. These measurements are used in adjusting a bandwidth of the filter to accommodate the channel quality while keeping the fixed delay, which minimizes the delay buffer size. The filter is then used to operate on the received sequence of data to provide coherent modulation.
    Type: Grant
    Filed: August 13, 2003
    Date of Patent: September 23, 2008
    Assignee: Motorola, Inc.
    Inventors: Bryan W. Zancho, Christopher P. Larosa, Alexandre Mallette, John P. Oliver
  • Patent number: 7426242
    Abstract: A correlation canceller modulates a communication signal over a plurality of channels and an epoch aperture by a plurality of interference response signals corresponding to linear response by one or more filtering effects to generate an inversely correlated communication signal.
    Type: Grant
    Filed: August 4, 2004
    Date of Patent: September 16, 2008
    Assignee: ViaSat, Inc.
    Inventor: William H. Thesling
  • Patent number: 7421009
    Abstract: A noise power estimation apparatus is disclosed. The noise power estimation apparatus includes: a part for calculating correlation between a received signal and a pilot signal so as to obtain a received power of the pilot signal for each path; a part for removing a multipath interference component from the received power of the pilot signal by using a predetermined power ratio between the pilot signal and a data signal so as to obtain a corrected received power of the pilot signal; a part for estimating an estimated total power of the pilot signal and the data signal included in the received signal based on the corrected received power and the predetermined power ratio; and a part for subtracting the estimated total power from a total power of the received signal so as to obtain a noise power.
    Type: Grant
    Filed: May 13, 2005
    Date of Patent: September 2, 2008
    Assignee: NTT DoCoMo, Inc.
    Inventors: Junichiro Kawamoto, Noriyuki Maeda, Kenichi Higuchi, Mamoru Sawahashi
  • Patent number: 7418046
    Abstract: Each transmitter is assigned a time-only pilot code, a frequency-only pilot code, or a time-frequency pilot code to use for pilot transmission. The pilot codes may be pseudo-random, orthogonal, and/or cyclic-shift codes. To obtain a channel estimate for a transmitter using a time-frequency pilot code composed of a time-only code and a frequency-only code, a receiver multiplies a set of received symbols for each symbol period with a set of code values for the frequency-only code to obtain a set of detected symbols and performs an IDFT on the set of detected symbols to obtain an initial impulse response estimate. The receiver performs code matching on multiple initial impulse response estimates derived for multiple symbol periods with the time-only code to obtain a final impulse response estimate for the desired transmitter. The receiver retains the first L channel taps and zeroes out remaining channel taps, where L is the expected channel length.
    Type: Grant
    Filed: December 22, 2004
    Date of Patent: August 26, 2008
    Assignee: QUALCOMM Inc.
    Inventors: Dhananjay Ashok Gore, Avneesh Agrawal, Tamer Kadous
  • Patent number: 7415061
    Abstract: A communication system performs burst noise cancellation. A transmitter produces and transmits a spread signal that comprises at least one known-value symbol spread by a plurality of non data-carrying orthogonal codes and data symbols spread by at least one data-carrying orthogonal code. The transmitter transmits the spread signal across a communication link that introduces burst noise. A burst noise detector determines burst noise affected chips of the orthogonal codes. A weight computation functional block calculates a plurality of complex-valued combining weights based upon the burst noise affected chips. A vector de-spreader and a linear combiner operate in combination to use the plurality of non data-carrying orthogonal codes, the at least one data-carrying orthogonal code, and the plurality of complex-valued combining weights to de-spread the received spread signal to produce the data symbols with the burst noise substantially removed.
    Type: Grant
    Filed: March 24, 2005
    Date of Patent: August 19, 2008
    Assignee: Broadcom Corporation
    Inventors: Bruce J. Currivan, Nabil R. Yousef, Thomas J. Kolze, Gottfried Ungerboeck
  • Publication number: 20080192809
    Abstract: A method and apparatus for transmitting and receiving data by performing an iterative multi-user detection is provided.
    Type: Application
    Filed: June 26, 2007
    Publication date: August 14, 2008
    Applicants: SAMSUNG ELECTRONICS CO., LTD, POSTECH ACADEMY-INDUSTRY FOUNDATION
    Inventors: Young-Doo KIM, Eung Sun KIM, Chang Wook AHN, Gi-Hong IM, Jong-Bu LIM, Tae-Won YUNE, Chan-Ho CHOI
  • Patent number: 7400608
    Abstract: The interference cancellation (IC) system (500) includes a plurality of IC units, for which IC is applied. Each IC unit has its spread spectrum code generator, delay devices, correlators or matched filters (MF), spreading circuits and subtracting and adding devices. The IC process in accordance with the invention includes using a bank of MF to despread the received signal at every time instant corresponding to every identified multipath of every user's transmitted signal. Based on the despread signals, an initial decision for the present information symbol of every user can be made using a single-user receiver such as, for example, the conventional Rake receiver or an equalizer. Based on the initial decisions, IC regenerates the multipath signals for each user using timed versions of the spread spectrum code, the delays of the multipaths, and the corresponding channel medium estimates.
    Type: Grant
    Filed: January 11, 2005
    Date of Patent: July 15, 2008
    Assignee: Texas Instruments Incorporated
    Inventors: Aris Papasakellariou, Alan Gatherer
  • Patent number: 7397840
    Abstract: A direct sequence spread spectrum receiver includes a first spreading code generator for receiving a first channel signal spectrum spread by a first spread code, while a second group of receivers use a second spreading code, where the first and second codes are partially correlated, so that, the first group of receivers receive all messages communicated while the second group of receivers only receives a portion of the messages. In this manner, a spread spectrum broadcast system can selectively communicate to a selected portion of receivers in a whole group of receivers by simply switching the spreading code at the transmitter.
    Type: Grant
    Filed: July 17, 2003
    Date of Patent: July 8, 2008
    Assignee: The Aerospace Corporation
    Inventor: Walter E. Lillo
  • Patent number: 7397842
    Abstract: A RAKE receiver circuit generates combining weights based on channel estimates and combining statistics that comprise channel coefficient statistics, noise statistics, and channel estimation error statistics. Together, these statistics incorporate the relationships in noise and channel estimation across two or more RAKE fingers, and thus improve combining weight generation. Exemplary determination of statistics comprises channel coefficient cross-correlations, noise cross-correlations, and channel estimation error cross-correlations. Determination of the statistics can be varied based on, for example, the assumption of default or nominal signal models.
    Type: Grant
    Filed: September 26, 2003
    Date of Patent: July 8, 2008
    Assignee: Telefonaktiebolaget LM Ericsson (publ)
    Inventors: Gregory E. Bottomley, Carmela Cozzo, Ali S. Khayrallah, Dignus-Jan Moelker
  • Patent number: 7391803
    Abstract: A system and method are provided for canceling interference present in a local channel signal received at a receiver. The system includes a controller and a finger demodulator assembly. The controller is capable of selecting at least one interfering pilot channel signal that has a signal strength above a threshold, where the selected interfering pilot channel signals comprises an interfering set of pilot channel signals. The finger demodulator assembly can then be capable of producing a corrected local channel signal based upon the interfering set of pilot channel signals during the idle state and/or access state.
    Type: Grant
    Filed: September 2, 2003
    Date of Patent: June 24, 2008
    Assignee: Nokia Corporation
    Inventors: Tao He, Jignesh Shah, Jian Huang
  • Patent number: 7391830
    Abstract: A receiver of digital data bursts is provided comprising an antenna array, a first space time filter having filter coefficients initialized by estimation over just training data in a received burst and providing symbol estimates and a second space time filter having filter coefficients initialized by estimation over the received burst and providing symbol estimates. In use at least one pass to determine a symbol estimate in the received burst is undertaken by each space time filter and a selector operates to determine which of the first and second filters provides the symbol estimate closer to an expected value.
    Type: Grant
    Filed: September 24, 2003
    Date of Patent: June 24, 2008
    Assignee: Lucent Technologies Inc.
    Inventors: Alexandr Kuzminskiy, Constantinos B Papadias
  • Patent number: 7388899
    Abstract: The ultra wide band communication system of the present invention includes a transmitter (station) and a receiver (station). The transmitter and the receiver employ spreading code comprised of code groups, which respectively comprise varied, auto-correlated codes. Consecutive information bits are spread and de-spread with differing code and the code groups are correlated with each other (e.g., orthogonal) so as to reduce channel impulse response estimation noise. At the receiver, subsequent channel estimates can be added or averaged with an initial channel estimate so as to reduce the channel impulse response estimation noise and thereby provide a relatively more accurate channel response.
    Type: Grant
    Filed: March 24, 2003
    Date of Patent: June 17, 2008
    Assignee: Texas Instruments Incorporated
    Inventor: Hirohisa Yamaguchi
  • Patent number: 7386035
    Abstract: Provided is a method of compensating for energy loss and eliminating inter-symbol interference (ISI) and inter-chip interference (ISI) in wireless signals, and a rake receiver for wireless LANs adopting the same. The rake receiver compensates for energy loss of a CCK signal transmitted in a multi-path wireless channel environment and eliminates ISI and ICI from the received CCK signal because a DFE structure per chip used for calculating ICI components, is connected in parallel with a DFE structure per symbol, thus eliminating ISI and ICI components.
    Type: Grant
    Filed: November 4, 2004
    Date of Patent: June 10, 2008
    Assignees: Samsung Electronics Co. Ltd., Research and Industrial Cooperation Group
    Inventors: Sung-hyun Hwang, Hyun-cheol Park, Yu-sung Lee
  • Patent number: 7385944
    Abstract: In a method of canceling interference, a base station selects a known highest data rate user transmission from a received first signal containing a group of user transmissions. The known highest rate user transmission may be configured as one or more frames, each frame including a control preamble and a plurality of encoded sub-frames. The control preamble and encoded sub-frames may be decoded, and the decoded sub-frames may be used for removing interference caused by the known highest rate user transmission to all remaining transmissions of the group.
    Type: Grant
    Filed: March 31, 2003
    Date of Patent: June 10, 2008
    Assignee: Lucent Technologies Inc.
    Inventors: Hongwei Kong, Kumud K. Sanwal, Subramanian Vasudevan, Yunsong Yang, Henry Hui Ye, Jialin Zou
  • Publication number: 20080130714
    Abstract: Interference in a wireless communication is minimized, or at least reduced, by scaling the symbols received from an interfering transmitter. Input samples from the interfering transmitter are isolated and decovered to generate received symbols. The gains of the received symbols are scaled to reduce the interference and the scaled symbols are covered to produce output samples that are spread to generate interference cancelled samples with reduced interference from the interfering transmitter. The function applied to scale the symbols may be linear or nonlinear.
    Type: Application
    Filed: January 25, 2008
    Publication date: June 5, 2008
    Applicant: QUALCOMM INCORPORATED
    Inventors: Thomas B. Wilborn, Brian Clarke Banister
  • Patent number: 7382821
    Abstract: A searcher uses an input signal, and for example, a matched filter to generate a first set of candidate paths. A selector uses the input signal and the first set of candidate paths to generate a second set of paths. The second set of paths is used to configure the fingers of a RAKE receiver. According to one aspect of the invention, the first set of candidate paths contains M paths, and the second stage uses M correlators to generate a set of M correlation values. The second stage uses the M correlation values to select N paths that are used to configure the N fingers of the RAKE receiver. According to another aspect of the invention, the first set of candidate paths contains M paths, and the second stage uses a multiple of M correlators to track the M paths and generate a set of M estimates. The second stage uses the M estimates to select N paths that are used to configure the N fingers of the RAKE receiver.
    Type: Grant
    Filed: January 24, 2007
    Date of Patent: June 3, 2008
    Assignee: Telefonaktiebolaget L M Ericsson (publ)
    Inventors: Roozbeh Atarius, Torsten J. Carlsson, Håkan B. Eriksson, Kjell B. Gustafsson, Torgny Palenius, Christer Östberg
  • Patent number: 7372895
    Abstract: A signal-path delay-estimation method includes correlating a computed coarse delay profile of at least one detected signal path cluster with a waveform to yield a strongest correlated peak for each of the at least one detected signal path cluster. The method also includes, for each of the at least one detected signal path cluster, using the strongest correlated peak to determine an adjusted delay-profile phase, re-sampling the computed coarse delay profile in accordance with the adjusted delay-profile phase, and detecting signal-path-cluster edges using the re-sampled computed coarse delay profile. This Abstract is provided to comply with rules requiring an Abstract that allows a searcher or other reader to quickly acertain subject matter of the technical disclosure. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).
    Type: Grant
    Filed: December 8, 2004
    Date of Patent: May 13, 2008
    Assignee: Telefonaktiebolaget LM Ericsson (publ)
    Inventor: Andres Reial
  • Patent number: 7372890
    Abstract: In at least some embodiments, a method for mitigating interference between an Ultra Wideband (UWB) device and a non-UWB device is provided. The method includes, dynamically determining if a frequency channel associated with the non-UWB device is being used. If the frequency channel is being used, the method adjusts a UWB frequency band used for UWB signal transmission.
    Type: Grant
    Filed: January 27, 2006
    Date of Patent: May 13, 2008
    Assignee: Texas Instruments Incorporated
    Inventors: Anuj Batra, Jaiganesh Balakrishnan, Srinivas Lingam
  • Patent number: 7369620
    Abstract: A channel noise estimating method and apparatus applied to a multi-carrier system are disclosed, where data symbols received by a receiving unit are applied to reconstruct the original transmitted data symbols. The reconstructing process is performed by either a soft decision or a hard decision technique to simulate the original transmitted data symbols. These simulated transmitted data symbols in company with the received data symbols are further applied to calculate the channel noise based on an LMS algorithm.
    Type: Grant
    Filed: December 2, 2003
    Date of Patent: May 6, 2008
    Assignee: Mediatek Incorporation
    Inventor: Hung Kun Chen