Using Angle Modulation Patents (Class 370/483)
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Patent number: 11147023Abstract: A user terminal according to an aspect of the present disclosure includes a transmitting/receiving section that performs at least one of transmission and reception of a demodulation reference signal (DMRS) for a physical shared channel, and a control section that determines a power for the DMRS without taking account of a resource element to which the DMRS is not allocated, with reference to a table providing a definition of a ratio of a power (EPRE) for each resource element of the physical shared channel to an EPRE for the DMRS to which a certain number of CDM groups is applied. According to one aspect of the present disclosure, it is possible to use the same transmission power for data symbols and DMRS symbols even in NR.Type: GrantFiled: April 6, 2018Date of Patent: October 12, 2021Assignee: NTT DOCOMO, INC.Inventors: Yuki Matsumura, Kazuki Takeda, Satoshi Nagata
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Patent number: 11140702Abstract: A radio communication system includes: a plurality of cells having different scrambling sequences, respectively, wherein at least two cells communicate with at lease two user terminals connected to different serving cells; and a controller which controls the plurality of cells and provides a single scrambling sequence to said at least two cells and said at least two user terminals for control signal transmission and reception.Type: GrantFiled: March 19, 2019Date of Patent: October 5, 2021Assignee: NEC CORPORATIONInventors: Le Liu, Yoshikazu Kakura, Naoto Ishii, Takamichi Inoue
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Patent number: 9768911Abstract: A method for operating a transmitting device includes mapping data to a transmission symbol in accordance with a constellation map assigned to a receiving device, wherein the constellation map is designed in accordance with a posteriori error rate derived from a transmitted signal, and transmitting the transmission symbol.Type: GrantFiled: June 11, 2015Date of Patent: September 19, 2017Assignee: Huawei Technologies Co., Ltd.Inventors: Mikhail Germanovich Bakulin, Vitaly Borisovich Kreyndelin, Gennady Vladimirovich Ovechkin, Javad Abdoli, Peiying Zhu, Ming Jia
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Patent number: 9681436Abstract: A method to allocate physical radio resources for both distributed and localized transmission schemes of ePDCCH and configure common and UE-specific search space for UE is provided. In one embodiment, a UE receives a first high-layer information to determine a first set of PRBs. The UE determines a first set of candidate ePDCCHs within the first set of PRBs, wherein one or more candidate ePDCCHs potentially carries DCI intended for the UE. The UE then decodes the first set of candidate ePDCCHs to obtain the DCI intended for the UE. Similar steps are performed for a second set of candidate ePDCCHs potentially carrying DCI intended for the UE. The allocated radio resources of the candidate ePDCCHs may be distributed or localized and constitute either common or UE-specific search space. Blind decoding complexity is reduced.Type: GrantFiled: August 10, 2016Date of Patent: June 13, 2017Assignee: MEDIATEK INC.Inventors: Pei-Kai Liao, Xiangyang Zhuang
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Patent number: 9294255Abstract: A method of handling an enhanced physical downlink control channel (EPDCCH) for a network of a wireless communication system comprises calculating the average number of available resource elements (REs) in one control channel element (CCE) for EPDCCH in a physical resource block (PRB); selecting an aggregation level from a first aggregation level set; calculating the number of available REs in a EPDCCH for the selected aggregation level according to the selected aggregation level and the average number of available REs in one CCE; selecting a first candidate number set according to a second comparison result between the number of available REs in the EPDCCH for the selected aggregation level and a second threshold; and determining an aggregation level and the number of blind decoding candidates corresponding to the determined aggregation level, for transmitting control information dedicated to a user equipment.Type: GrantFiled: September 6, 2013Date of Patent: March 22, 2016Assignee: HTC CorporationInventor: Chih-Yao Wu
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Patent number: 9155091Abstract: A method for configuring a search space of a downlink control channel is provided. The method includes determining the parameters for Enhanced Physical Downlink Control Channel (E-PDCCH) candidates of each aggregate level according to the number of Resource Elements (RE) in a subframe and/or the number of bits of Downlink Control Information (DCI) formats, when the parameters for E-PDCCH candidates of E-PDCCH search space is configured, determining, by a User Equipment (UE), the parameters for E-PDCCH candidates according to a current downlink subframe and a detected DCI format, and detecting blindly, by the UE, the E-PDCCH candidates in the E-PDCCH search space corresponding to the parameters for E-PDCCH candidates. The present invention also provides a UE and a base station. Application of the present invention can improve the flexibility of the base station scheduling, and reduce the possibility that the E-PDCCHs of different UEs block each other.Type: GrantFiled: March 15, 2013Date of Patent: October 6, 2015Assignee: Samsung Electronics Co., Ltd.Inventors: Yingyang Li, Chengjun Sun
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Patent number: 9042874Abstract: A method of dynamically invoking a simultaneous ring feature in a telecommunications network includes: identifying a call directed to an address of an end user device (30); notifying user equipment (20) other than the end user device (30) of the identified call; and, receiving an indication from the user equipment (20) whether or not the simultaneous ring feature should be invoked so as to establish a call leg to the user equipment (20).Type: GrantFiled: February 29, 2012Date of Patent: May 26, 2015Assignee: Alcatel LucentInventor: Alan E. Frey
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Patent number: 8908492Abstract: Methods of allocating orthogonal resources of a wireless communication network to a user equipment (UE) that uses transmit diversity are disclosed. In one or more embodiments, the UE is configured to transmit a reference symbol and a modulated symbol on multiple orthogonal resources on an antenna. The method includes: selecting, by the UE, a first and a second orthogonal resource, respectively, from a plurality of orthogonal resources according to the state of information bits to be communicated by the UE; and transmitting, by the UE, the reference and data symbols on the first and the second orthogonal resource, respectively, on one antenna. The first and the second resource are different for at least one of the states of the information bits. The first and the second resource are both in the same physical resource block.Type: GrantFiled: May 8, 2012Date of Patent: December 9, 2014Assignee: BlackBerry LimitedInventors: Youn Hyoung Heo, Robert Mark Harrison, Masoud Ebrahimi Tazeh Mahalleh
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Patent number: 8670789Abstract: Methods and apparatus for efficient two-stage paging wireless communications systems are described. Wireless terminals are assigned to paging groups. A few first paging message information bits are modulated (using non-coherent modulation) into a first paging signal and communicated from a base station to wireless terminals. WTs wake-up, receive the first paging signal and quickly ascertain whether its paging group should expect a second paging signal, if so, the WT is operated to receive the second paging signal; otherwise, the WT goes back to sleep conserving power. The base station modulates (using coherent modulation) a number of second message information bits into a second paging signal and transmits the signal to WTs. From the information in first and second paging signals, a WT can determine that it is the paged WT and process the paging instructions. The intended paged WT can transmit an acknowledgement signal on a dedicated uplink resource.Type: GrantFiled: March 23, 2010Date of Patent: March 11, 2014Assignee: QUALCOMM IncorporatedInventors: Rajiv Laroia, Junyi Li, Sundeep Rangan, Prashanth Hande
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Patent number: 8660205Abstract: A method and apparatus employing statistical physics energy minimization methods to signal constellation design. By using statistical physics concepts, an energy-efficient signal constellation design algorithm (EE-SCDA) is described. In the presence of amplified spontaneous emission (ASE) noise and channel impairments, we use EE-SCDA to determine a source distribution, and represent the signal constellation design as a center of mass problem. Furthermore a discrete-time implementation of D-dimensional transceiver as well as corresponding EE polarization-division multiplexed (PDM) system is described.Type: GrantFiled: June 3, 2012Date of Patent: February 25, 2014Assignee: NEC Laboratories America, Inc.Inventors: Ivan B. Djordjevic, Lei Xu, Ting Wang
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Patent number: 8548007Abstract: A method is provided for determining a transmission rate of a control response frame for acknowledging data receipt in a wireless local area network. The method includes obtaining transmission parameters of a transmitting station from a data transmission frame received from the transmitting station, searching a receiving station for transmission parameters which correspond to the transmission parameters of the transmitting station, determining the transmission rate of the control response frame according to transmission parameters of the receiving station if the transmission parameters corresponding to the transmission parameters of the transmitting station are found in the receiving station, and determining a maximum rate among a set of basic transmission rates to be the transmission rate of the control response frame if the transmission parameters corresponding to the transmission parameters of the transmitting station are not found in the receiving station.Type: GrantFiled: May 17, 2010Date of Patent: October 1, 2013Assignee: Samsung Electronics Co., Ltd.Inventors: Chang-yeul Kwon, Chil-youl Yang, Kyung-ik Cho, Se-young Shin
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Patent number: 8537862Abstract: A method is provided for applying HOM to a PDCCH to transmit control information from an access node to a UE. The method comprises: selecting a DCI format for a HOM PDCCH; determining a DCI block of the HOM PDCCH according to the selected DCI format; generating a sequence of coded bits to be transmitted from the DCI block; multiplexing the sequence of coded bits of the HOM PDCCH with coded bits of other PDCCHs to form a sequence of multiplexed bits; scrambling the sequence of multiplexed bits to form a sequence of scrambled bits; modulating the scrambled bits to form a sequence of modulation symbols; and transmitting the sequence of modulation symbols, where a PDCCH is transmitted on an aggregation of one or more CCEs.Type: GrantFiled: June 30, 2011Date of Patent: September 17, 2013Assignee: Blackberry LimitedInventors: Yufei Wu Blankenship, Michael Eoin Buckley, Zhijun Cai, Hua Xu, Sophie Vrzic, Shiwei Gao, Youn Hyoung Heo
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Patent number: 8509351Abstract: The present disclosure relates to multi-mode RF circuitry using a single IQ modulator topology that may support different communication standards, including enhanced data rates for global system for mobile communications evolution (EDGE) and EDGE evolution by dividing certain modulation functions between a frequency synthesizer and an IQ modulator. Specifically, during a standard modulation mode, which may be used to support many communications standards, the frequency synthesizer provides an un-modulated RF carrier signal to the IQ modulator, which either phase modulates or phase and amplitude modulates the un-modulated RF carrier signal to provide a standard modulated RF signal.Type: GrantFiled: September 30, 2010Date of Patent: August 13, 2013Assignee: RF Micro Devices, Inc.Inventors: Nadim Khlat, Alexander Wayne Hietala, Marcus Granger-Jones
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Publication number: 20130121350Abstract: Systems and methods are presented for transmitting additional data over preexisting differential COFDM signals by modulating existing data carriers with a phase and an amplitude offset. In exemplary embodiments of the present invention, additional data capacity can be achieved for an COFDM signal which is completely backwards compatible with existing satellite broadcast communications systems. In exemplary embodiments of the present invention additional information can be overlayed on an existing signal as a combination of amplitude and phase offset from the original QPSK symbols, applied for each information bit of the overlay data. With two additional levels of modulation, a receiver can demodulate the information from each of the previous stages and combine the information into a suitable format for soft decoding. The first stage of demodulation will be recovery of overlay data from the amplitude modulated D8PSK.Type: ApplicationFiled: October 5, 2012Publication date: May 16, 2013Applicant: Sirius XM Radio, Inc.Inventor: Sirius XM Radio, Inc.
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Patent number: 8295386Abstract: A nonlinear filter includes: a determination unit that determines, based on I and Q signals inputted into the determination unit, whether or not to perform pulse insertion; a rotation detector that detects a rotation direction of the I and Q signals on an IQ plane with respect to the origin of the IQ plane; a pulse generator that generates, when the determination unit determines to perform the pulse insertion, a pulse of which at least one of the direction and the magnitude is determined in accordance with at least the detected rotation direction; and an adder that inserts the pulse into the I and Q signals and outputs resultant I and Q signals.Type: GrantFiled: June 14, 2010Date of Patent: October 23, 2012Assignee: Panasonic CorporationInventors: Toru Matsuura, Kenichi Mori, Wayne S. Lee
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Publication number: 20120243558Abstract: A signal transmission system including a transmitting device and a receiving device, including: the transmitting device including: a first modulator that modulates a frequency of a control signal; and a first multiplexer that multiplexes the frequency-modulated control signal onto a DVI (Digital Visual Interface) signal to be transmitted to the receiving device via a single network cable; and the receiving device including: a first separator that separates the frequency-modulated control signal from the multiplexed DVI signal; and a first demodulator that demodulates the separated control signal.Type: ApplicationFiled: February 29, 2012Publication date: September 27, 2012Applicant: FUJITSU COMPONENT LIMITEDInventor: Masato OZAWA
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Patent number: 8072873Abstract: A process is described to build physical layer frames with a modcode adapted to the signal quality of a destination terminal. Data packets assigned to the same modcode may be sent in the same frame, although packets associated with higher modcodes may be used to complete a frame before switching to the applicable higher modcode for construction of subsequent frames. After an interval, the order of progression is restarted with an out of order packet above a threshold age. Flow control filtering mechanisms and a variable reliability margin may be used to adapt dynamically to the current data traffic conditions.Type: GrantFiled: January 20, 2010Date of Patent: December 6, 2011Assignee: ViaSat, Inc.Inventor: William H. Thesling
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Patent number: 7756001Abstract: An apparatus for and method of deciding symbols in a M-ary phase shift keying (MPSK) system are provided. The apparatus includes: a linear transform unit performing linear transform, to which a phase error is applied, of a received pair of symbols; and a symbol decision unit deciding a transmitted symbol corresponding to the received pair of symbols according to the sign value of the transformed symbol pair. According to the apparatus and method, degradation of a symbol error rate caused by a phase error when an MPSK signal is demodulated can be improved and a phase error can be estimated through a simple method.Type: GrantFiled: November 30, 2006Date of Patent: July 13, 2010Assignee: Electronics and Telecommunications Research InstituteInventors: Jin A Park, Seung Keun Park, Pyung Dong Cho, Hyeong Ho Lee
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Patent number: 7675842Abstract: A process is described to build physical layer frames with a modcode adapted to the signal quality of a destination terminal. Data packets assigned to the same modcode may be sent in the same frame, although packets associated with higher modcodes may be used to complete a frame before switching to the applicable higher modcode for construction of subsequent frames. After an interval, the order of progression is restarted with an out of order packet above a threshold age. Flow control filtering mechanisms and a variable reliability margin may be used to adapt dynamically to the current data traffic conditions.Type: GrantFiled: October 30, 2006Date of Patent: March 9, 2010Assignee: ViaSat, Inc.Inventor: William H. Thesling
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Method of determining random access channel preamble detection performance in a communication system
Patent number: 7643438Abstract: In a method for determining link level performance of random access channel (RACH) preamble detection in a wireless communication system, link level performance results may be obtained without having to perform extensive simulation. Link-level performance results of RACH preamble detection may be characterized by determining a conditional detection probability. The conditional detection probability may be conditioned upon an instantaneous channel coefficient, and the conditional detection probability may be expressed in terms of an instantaneous detection metric. Instantaneous link-level performance may be characterized using a look-up table, so that a system model evaluated in accordance with the method may accurately represent instantaneous system behavior.Type: GrantFiled: August 28, 2003Date of Patent: January 5, 2010Assignee: Alcatel-Lucent USA Inc.Inventors: Jung Ah Lee, Shirish Nagaraj -
Patent number: 7583702Abstract: The present invention discloses a method of transmitting a first signal and a second signal in a wideband code-division multiple access network, wherein a probability of the appearance of signal bit “1” or “0” in each signal of the first signal and the second signal is remarkably higher than a probability of the appearance of “0” or “1”, the method including: a step of determining constellation points, for determining combinations of different states of the first signal and the second signal and for determining each combination as a constellation point; a step of determining locations of constellation points, for determining a location of each constellation point on I-Q plane based on a priori knowledge of said combination; and a step of transmission, for, after modulating said different combinations in different ways according to the location of each constellation point, transporting them to a user equipment via a physical channel.Type: GrantFiled: December 7, 2005Date of Patent: September 1, 2009Assignee: Alcatel LucentInventors: Zongchuang Liang, Hua Chao, Xin Xu, Luoning Gui
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Patent number: 7443919Abstract: In various embodiments, techniques are provided to determine channel characteristics of various communication systems such as OFDM systems or systems using a plurality of transmit antennas by using various sets of training symbols.Type: GrantFiled: October 10, 2006Date of Patent: October 28, 2008Assignee: AT&T Corp.Inventor: Ye Li
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Publication number: 20080225895Abstract: A signal generation apparatus and signal receiving apparatus according to an Interleaved Frequency Division Multiple Access scheme is provided. The signal generation apparatus generates a plurality of complex symbols by digital-modulating a plurality of data symbols, and rotates the generated plurality of complex symbols in a plurality of each different phase angles. The signal generation apparatus generates a plurality of transmission symbols by repeating a plurality of rotated complex symbols at predetermined times, and rotating the repeatedly generated plurality of transmission chips in phase angles of an orthogonal phase sequence for the respective users. When the signal receiving apparatus receives the plurality of transmission symbols generated as described above, the maximum diversity gain may be obtained.Type: ApplicationFiled: August 22, 2006Publication date: September 18, 2008Applicant: Electronics and Telecommunications Research InstituteInventors: Seung-Joon Lee, Jong-Ee Oh, Dong-Seung Kwon
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Patent number: 7127001Abstract: In various embodiments, techniques are provided to determine channel characteristics of various communication systems such as OFDM systems or systems using a plurality of transmit antennas by using various sets of training symbols.Type: GrantFiled: September 30, 2005Date of Patent: October 24, 2006Assignee: AT&T Corp.Inventor: Ye Li
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Patent number: 6876672Abstract: A method of transmitting data on multiple carriers is disclosed, the method consisting, on a transmitter side, of binary to signal coding of the data to be transmitted so as to form modulation signals, of modulating a plurality of sub-carriers with the modulation signals as to form symbols, referred to as OFDM symbols, and then of transmitting, over a channel between the transmitter and a receiver, the OFDM symbols at a rate which is related to a sampling frequency referred to as the transmitter sampling frequency, and, on the receiver side, of determining, from a clock signal at a frequency related to a sampling frequency referred to as the receiver sampling frequency, an analysis window for the signal received from the transmitter so as to form a block of samples, and of estimating the transmitted modulation signals by demodulating the sub-carriers for the block of samples under consideration.Type: GrantFiled: July 24, 2000Date of Patent: April 5, 2005Assignee: Mitsubishi Denki Kabushiki KaishaInventor: Damien Castelain
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Patent number: 6704366Abstract: A transmitter for a radio transmission system has an encoder for encoding data according to an error correction code and supplying a digital output stream of bits which are then distributed over a selectable number of carriers belonging to a group of carriers that are uniformly distributed over a transmission channel, so as to constitute a frequency division multiplex. Then the stream is subjected to time interleaving responsive to a distribution given by the bit spreading module which achieves distribution and frequency interleaving operating on the carriers; the stream is then modulated in phase or possibly a phase and amplitude.Type: GrantFiled: June 7, 2000Date of Patent: March 9, 2004Assignee: Sagem SAInventors: Bernard Combes, Pascal Paqueron, Cyril Voillequin, Pierre Lemahieu
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Patent number: 6693917Abstract: A system for transmitting subchannel data over the same media as high speed data, especially DC balanced high speed data. A digital transmitter receives subchannel data and modulates it onto a subchannel carrier as the host signal in the preferred embodiment using frequency shift keying. The FSK subchannel carrier is added by superposition to the high speed data signal. At the receiver, a low pass filter filters out the subchannel carrier frequency components which are then amplified and subjected to a two-pole anti-aliasing filter to remove the third and fifth harmonics. Analog-to-digital conversion is followed by a digital mix down to remove the subchannel carrier component using a local oscillator at the subchannel carrier frequency. An FIR low pass filter having a triangular time domain response performs anti-aliasing and leaves as an output only frequency components at the positive and negative deviation frequency for Mark and Space.Type: GrantFiled: August 27, 1999Date of Patent: February 17, 2004Assignee: Broadcom CorporationInventors: Richard Karl Feldman, Farivar Farzaneh, Michael Timothy Kauffman
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Patent number: 6587452Abstract: A mapping memory, for use with a transmitter, for mapping a first signal segment and a second signal segment of a packet so that each signal segment has the same average power level. Each signal segment is characterized by a different modulation format. The first signal segment might use BPSK, while the second signal segment might use QAM, having multiple amplitude levels.Type: GrantFiled: January 4, 1999Date of Patent: July 1, 2003Assignees: Golden Bridge Technology, Inc., Seiko Epson CorporationInventors: Sorin Davidovici, Emmanuel Kanterakis, Izumi Iida, Norio Hama, Nobuhiko Kenmochi
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Patent number: 6539008Abstract: A power control bit inserting method between a base station and a terminal. The base station and the terminal each use a plurality of adjacent frequency bands as signal paths with independent signal paths of a real part and an imaginary part given to each frequency. In the power control bit inserting method, a unit time is set to a power control group period, n-bit data is allocated to each signal path, the power control group period is divided by the number of signal paths, and a power control bit is inserted in each divided segment, so that the insertion positions in the real and imaginary parts of each frequency are spaced from each other by n/2 bit and the start position of the real signal path of each frequency is inserted at an appointed bit position of the corresponding frequency.Type: GrantFiled: November 2, 1998Date of Patent: March 25, 2003Assignee: Samsung Electronics, Co., Ltd.Inventors: Jae-Min Ahn, Young-Ky Kim, Soon-Young Yoon, Hee-Won Kang, Felix Kwang-Wook Yie, Seung-Hyun Kong
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Patent number: 6477153Abstract: A communication satellite system (100) is established using one or more satellite constellations (110, 120). The two or more satellite groups (110, 120) are connected via long range crosslinks (145) which provide a communication path between the long range satellites (150, 170) in the two satellite groups (110, 120). Each satellite group (110, 120) comprises long range satellites (150, 170) and short range satellites (160, 180) which are interconnected using short range crosslinks (155, 175). A single antenna on each satellite provides both crosslinks. The long range crosslink (145) is established using the antenna's main beam and the short range crosslinks (155, 175) are established using the antenna's sidelobes.Type: GrantFiled: April 17, 2000Date of Patent: November 5, 2002Assignee: Motorola, Inc.Inventors: Raymond Joseph Leopold, Keith Andrew Olds, Bary Robert Bertiger
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Patent number: 6456650Abstract: In a splitterless Digital Subscriber Line (DSL) modem 30, a receiver architecture (100) that permits monitoring of harmonics within the upstream channel of a DSL connection. The receiver (100) can detect the harmonics by monitoring the harmonics in some empty tones or specified tones. A threshold can be set to differ the normal noise power and harmonics power in those empty or specified tones. When a POTS device (10) coupled to same wire line pair (20) as the DSL modem (30) goes off-hook, the DSL modem (30) can switch from the normal state to an off-hook state in which the harmonics are reduced to minimum by transmitting only the upper sub-band tones of the upstream transmission channel at reduced power levels.Type: GrantFiled: February 4, 1999Date of Patent: September 24, 2002Assignee: Texas Instruments IncorporatedInventors: Yaqi Cheng, Adam M. Chellali, Michael O. Polley
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Patent number: 6381252Abstract: A method and system for managing and allocating multiple communication resources to ensure relatively equal usage. The selection of the resource can be performed by retrieving a pointer value, and testing the resource associated with the pointer value monitoring the call duration over this resource and appropriately updating it's status (if the call duration is below the threshold, a bad call count for the channel is incremented. And when the bad call count exceeds the threshold the channel is marked as faulty). The pointer value as necessary to find a usable resource, and a usable resource is selected. The pointer value can be modified either before the testing of the initially-selected resource, or after the final selection of the usable resource.Type: GrantFiled: August 17, 2000Date of Patent: April 30, 2002Assignee: Armilliare Technologies, Inc.Inventors: Kwok-Leung Li, Shiuan-Haur Lu, Chih-Lung Sung, Sy-Ling Yen, Yuan-Shiang Chang
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Patent number: 6181924Abstract: A method and system for rejecting interfering signals in a wireless communication system employing antenna diversity. According to the method, the angle between an interfering signal and a desired carrier signal is determined and used to estimate an offset angle. The offset angle is incrementally adjusted such that, when added to the received signal, the carrier-to-interference (C/I) ratio of the received signal is substantially maximized.Type: GrantFiled: July 1, 1997Date of Patent: January 30, 2001Assignee: Telefonaktiebolaget LM Ericsson (publ)Inventors: Michael Eklund, Thomas {umlaut over (O)}stman
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Patent number: 5809030Abstract: The demodulation of data modulated on a set of carriers with equidistant frequencies by a plurality of transmitters (T1 . . . Tn) is executed in the present transmission system (TS) by a discrete multitone receiver (DMT-R). The transmitters (T1 . . . Tn) in the transmission system (TS) modulate their data on subsets of carriers which form part of the set of carriers with equidistant frequencies. These transmitters (T1 . . . Tn) are possibly additionally equipped with a cyclic prefix adder (CPA); synchronization between them is guaranteed if a predefined condition is fulfilled.Type: GrantFiled: January 30, 1996Date of Patent: September 15, 1998Assignee: Alcatel N.V.Inventors: Denis Julien Gilles Mestdagh, Martin Louis Florence De Prycker
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Patent number: 5666382Abstract: A method and apparatus for communicating over a track circuit which includes an interference signal. The invention includes sampling the interference signal on the track circuit at a predetermined sampling frequency to produce a sampled interference signal, detecting interference at a predetermined first sub-carrier frequency based on a fast Fourier transform of the sampled interference signal, forming a vector signal corresponding to a predetermined second sub-carrier frequency related to the predetermined sampling frequency and different from the predetermined first sub-carrier frequency, performing an inverse fast Fourier transformation on the vector signal to form a series communication signal, coupling the series communication signal to the track circuit, sampling the series communication signal on the track circuit at the predetermined sampling frequency from a sampled communications signal, and recovering the vector signal based on a fast Fourier transform of the sampled communication signal.Type: GrantFiled: February 28, 1994Date of Patent: September 9, 1997Assignee: ABB Daimler-Benz Transportation (North America) Inc.Inventor: Prashant B. Thakore
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Patent number: 5636247Abstract: A system for transmitting information over an OFDM channel using phase shift keying encoding employs a bit mapping encoder to reduce the crest factor (ratio of peak voltage to RMS voltage). For a 16 subchannel OFDM system using QPSK encoding, a first set of four symmetrically positioned pairs of subchannels is used to encode two bits of information on each subchannel. A second set of four symmetrically positioned pairs of subchannels is used to encode only one bit of information on each subchannel, with the resultant phasor for each pair of the second set of pairs of subchannels being orthogonal to the resultant phasor for one of the pairs of the first set of subchannels. With this arrangement, the crest factor is reduced.Type: GrantFiled: March 21, 1995Date of Patent: June 3, 1997Assignee: Lucent Technologies Inc.Inventors: Adriaan Kamerman, Anjur S. Krishnakumar