By Signal Strength Patents (Class 455/134)
  • Patent number: 6549774
    Abstract: A satellite receiver is switchable between an operating mode wherein the receiver is capable of generating an output signal using received signals from one or a plurality of satellites, aid another operating mode wherein the receiver generates an output signal using signals received from only one satellite. The former operating mode is useful when the receiver is operating in a mobile environment. The latter operating mode is useful when the receiver is operating in a fixed environment. The receiver is configured to detect the mode in which it is operating. The receiver comprises at least two recevier arms for processing a broadcast signal from a selected one of two satellites. The receiver disables one of the arms when the receiver is stationary.
    Type: Grant
    Filed: November 4, 1999
    Date of Patent: April 15, 2003
    Assignee: XM Satellite Radio Inc.
    Inventors: Joseph M. Titlebaum, Robert L. Acker, David L. Brown
  • Patent number: 6507602
    Abstract: A receiving apparatus comprises a receiver receiving signals via multiple propagation paths having different propagation delays and converting the signals to digital samples for processing. A channel estimator is operatively coupled to the receiver for correlating periodically selected groups of the digital samples corresponding to known symbols and periodically producing numerical estimates related to amplitudes and phases of the delayed propagation paths. A filter system filters the numerical estimates using filters periodically adapted to center frequencies of variations of the numerical estimates. A data decoder is operatively coupled to the receiver and the filter system for decoding data using the filtered estimates and the digital data.
    Type: Grant
    Filed: January 7, 1999
    Date of Patent: January 14, 2003
    Assignee: Ericsson, Inc.
    Inventor: Paul W. Dent
  • Publication number: 20020183026
    Abstract: The object of the present invention is to insure the communication quality best suited to the type of data between the transmission system and the receiver. In the wireless communication system 1 for controlling the data communication quality between the transmission system 2 to transmit contents and the mobile wireless terminal 8 to receive contents from said transmission system 2 via the predetermined communication path 15, since the transmission system 2 changes the modulation system in the data output unit 13 corresponding to the type of contents to be transmitted to the mobile wireless terminal 8, the data communication quality between said transmission system 2 and the mobile wireless terminal 8 can be controlled. Thereby, the data transmission from the transmission system 2 to the mobile wireless terminal 8 can be executed according to the modulation system best suited to the type of contents holding the predetermined communication quality.
    Type: Application
    Filed: June 11, 2002
    Publication date: December 5, 2002
    Inventor: Tetsuya Naruse
  • Patent number: 6472947
    Abstract: An antenna circuit is described which makes it possible to suppress intermodulation products. This antenna circuit includes an antenna connection device to which at least one first antenna can be connected, and the antenna connection device can be connected to an output of the antenna circuit over at least two signal paths. An antenna signal can be transmitted over each signal path. Transmission of a second antenna signal over a second signal path is attenuated by a predetermined attenuation value in comparison with a transmission of a first antenna signal over a first signal path. An analyzer unit is provided to determine the level of a weighting signal which is derived from an antenna signal transmitted to the output of the antenna circuit. An operating device is provided to connect only the first signal path to the output of the antenna circuit when the detected level is below a first predetermined level.
    Type: Grant
    Filed: July 3, 2001
    Date of Patent: October 29, 2002
    Assignee: Robert Bosch GmbH
    Inventor: Carsten Zeitz
  • Patent number: 6470194
    Abstract: The radio communication apparatuses and radio communication methods of the present invention detect the timing of an incoming wave, perform adaptive array antenna reception at the timing of the incoming wave, calculate a new weighting coefficient from the weighting coefficient of the reception result, detect the reception power of the desired wave and SIR level from the weighting coefficient and the received signal, select a weighting coefficient with the greater level and carry out transmission using the weighting coefficient selected above.
    Type: Grant
    Filed: March 19, 1999
    Date of Patent: October 22, 2002
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Kazuyuki Miya, Katsuhiko Hiramatsu
  • Patent number: 6456830
    Abstract: In the conventional diversity reception, information included in each non-selected signal does not contribute to an improvement in the reliability of communications, and transmitting power has been dissipated to satisfy required communication quality. Owing to the setting of encoding in respective base stations to injection, signals each including the same contents, which are received by a mobile station, are used for increasing the reliability of communications without depending on the number of the signals which were capable of being received by the mobile station, to thereby reduce transmitting power for satisfying required communication quality.
    Type: Grant
    Filed: August 17, 2001
    Date of Patent: September 24, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Atsushi Ogino, Hideya Suzuki, Tomoaki Ishifuji
  • Publication number: 20020123314
    Abstract: A determination part obtains an available communication quality value from required communication quality values of terminals currently on connection, and a maximum permissible communication quality value determined according to a design of the radio communication system, and, when the available communication quality value is larger than a required communication quality value of a new terminal, the determination part accepts connection for the new terminal.
    Type: Application
    Filed: December 27, 2001
    Publication date: September 5, 2002
    Applicant: NTT DoCoMo, Inc
    Inventors: Daisuke Kitazawa, Hijin Sato, Narumi Umeda
  • Patent number: 6426693
    Abstract: A emergency communication device which performs self diagnosing by repeatedly transmitting a weak signal, which can only be received by an antenna, among a plurality of antennas in a fixed time interval. When the weak signal is not received due to the occurrence of an accident, theft or the like, the occurrence of the emergency is communicated to an emergency data receiving center.
    Type: Grant
    Filed: November 18, 1999
    Date of Patent: July 30, 2002
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Jin Inomata
  • Patent number: 6421370
    Abstract: A spread spectrum communication system includes a plurality of mobile stations and a plurality of base stations that share the same frequency and operate independently. Each of the base stations can serve as a local base station and a non-local base station and has an element for always transmitting a pilot signal (base station reference signal) at a constant power level. Each of the mobile stations also has a quality measuring element for measuring base station reference signals received from the local base station and an adjacent base station serving as a non-local base station, and a transmission power controlling element for controlling the power level of a signal transmitted from the relevant mobile station corresponding to the measured results in such a manner that when the relevant mobile station has approached the adjacent base station, the transmission power controlling element decreases the power level of the transmission signal.
    Type: Grant
    Filed: November 19, 1998
    Date of Patent: July 16, 2002
    Assignee: NEC Corporation
    Inventor: Takahiro Yasaki
  • Patent number: 6408169
    Abstract: The present invention relates to a base station of a radio system whose antenna means (11) include: means (6 to 8) for receiving signals associated with the same logical channel by at least two antenna beams (1 to 4), measuring means (8) for measuring the signal level of the signals received by the antenna beams, and control means (8) for selecting one or more antenna beams (1 to 4) and for supplying the signals of the selected antenna beam to a receiver unit (5) of the base station (BTS1). In order that the best possible signal would be definitely transmitted to the base station, the base station (BTS1) comprises means for measuring the quality of the signals and for generating a quality signal (BER) and for supplying it to the control means (8), and the control means (8) are arranged to select an antenna beam (1 to 4) on the basis of the signal level measured by the measuring means and the quality signal (BER) supplied to the control means.
    Type: Grant
    Filed: November 20, 1998
    Date of Patent: June 18, 2002
    Assignee: Nokia Telecommunications Oy
    Inventor: Jorma Pallonen
  • Publication number: 20020072343
    Abstract: A receiver that uses multiple antennas to receive signals arriving over multiple paths and is configured for enhanced received signal path detection accuracy and improved reception quality includes receive weight generating means that generates receive weights for every antenna based on signals received from the antennas, summing means that calculates sums of results obtained by multiplying the signals from the antennas and the receive weights of the individual antennas generated by the receive weight generating means, and path detection means that detects the paths of the received signals based on the sums calculated by the summing means.
    Type: Application
    Filed: September 20, 2001
    Publication date: June 13, 2002
    Inventor: Tetsuhiko Miyatani
  • Publication number: 20020062367
    Abstract: A communication network system includes a plurality of client computers communicatively coupled to a network, which in turn is coupled to one or more server computers and at least one database. A method for reviewing and tracking workflow tasks, anomalies and other information using the system provides real-time access of the status of tasks and projects on a continuing basis. Individuals interact with the system to provide updates to the status of tasks. The system automatically escalates the completion of an overdue task or anomaly that has failed to be completed within a predetermined time period.
    Type: Application
    Filed: January 26, 2001
    Publication date: May 23, 2002
    Inventors: J. Dale Debber, Russell D. Ribb
  • Patent number: 6356604
    Abstract: The invention relates to a receiving method and a receive for a radio system. The receiver filters a received signal group propagated on several channels using channel filters (31) to generate separate channel specific signals. These channel specific signals are searched in device (35) for one or more signals (50) stronger than the others. Feed back is performed on these strongest signals (50) and they are subtracted from the received signal group in connector (21) in order to equalize the power levels of the signal group.
    Type: Grant
    Filed: July 13, 1998
    Date of Patent: March 12, 2002
    Assignee: Nokia Telecommunications Oy
    Inventor: Matti Kiiski
  • Patent number: 6347220
    Abstract: In a CDMA wireless base station, signals that have been received by a plurality antenna elements of an array antenna on the receiving side are subjected to beam forming by a reception beam former to electrically form a plurality of uplink beams. Reception is carried out based upon the optimum beam (e.g., the beam for which the power is maximum) among the plurality of uplink beams. A transmission beam former for subjecting a transmission signal to beam forming is provided. Based upon whether an uplink reception signal is present or not, a controller performs control so as to carry out downlink beam forming, thereby forming a downlink transmission beam in a direction identical with that of the optimum uplink reception beam, or in such a manner that downlink beam forming is not carried out.
    Type: Grant
    Filed: August 31, 1998
    Date of Patent: February 12, 2002
    Assignee: Fujitsu Limited
    Inventors: Yoshinori Tanaka, Shuji Kobayakawa, Masafumi Tsutsui
  • Publication number: 20020016156
    Abstract: In the conventional diversity reception, information included in each non-selected signal does not contribute to an improvement in the reliability of communications, and transmitting power has been dissipated to satisfy required communication quality. Owing to the setting of encoding in respective base stations to injection, signals each including the same contents, which are received by a mobile station, are used for increasing the reliability of communications without depending on the number of the signals which were capable of being received by the mobile station, to thereby reduce transmitting power for satisfying required communication quality.
    Type: Application
    Filed: August 17, 2001
    Publication date: February 7, 2002
    Applicant: Hitachi, Ltd.
    Inventors: Atsushi Ogino, Hideya Suzuki, Tomoaki Ishifuji
  • Patent number: 6330429
    Abstract: Received channels are grouped into channel groups in which each channel group includes channel members with commensurate signal parameter values to enhance performance of a wireless communications system. A data processing system establishes boundaries of each channel group to achieve an approximately equivalent quality of service (e.g., blocking rate) for each channel group based on the probabilities of occurrence of measured signal parameter values.
    Type: Grant
    Filed: April 14, 1999
    Date of Patent: December 11, 2001
    Assignee: Lucent Technologies, Inc.
    Inventor: Allen He
  • Patent number: 6327312
    Abstract: A radio receiver discriminates between narrowband and wideband radio frequency (RF) signals on the basis of the rate of increase of the integrated energy level of the received signal. The receiver comprises a receive section adapted to receive and downconvert RF input signals to intermediate frequency (IF) signals, and a received signal strength indicator coupled to the receive section and providing a receiver energy signal corresponding to the energy of the IF signals. A discrimination section receives the energy signal, and determines whether the RF input signals are narrowband or wideband by detecting the rate of increase of the integrated level of the receiver energy signal.
    Type: Grant
    Filed: June 24, 1998
    Date of Patent: December 4, 2001
    Assignee: Intermec IP Corp.
    Inventors: Alan F. Jovanovich, John W. Mensonides, Bruce G. Warren
  • Publication number: 20010038328
    Abstract: A multifunction remote keyless entry system is provided that increases functionality of the transmitter without increasing the size of the transmitter unit by having certain buttons on the transmitter perform multiple functions based on the distance from the vehicle. More specifically, actuation of a button on the portable transmitter unit triggers operation of a first designated function if the transmitter is outside a predetermined range from the vehicle. Actuation of the same button within the predetermined range will trigger operation of a second designated function. Thus, one button performs at least two functions depending on the distance the user is from the vehicle. In a further embodiment, the same button could trigger operation of a set of different functions as a function of multiple, concentric zones around the vehicle.
    Type: Application
    Filed: April 4, 2001
    Publication date: November 8, 2001
    Inventors: Ronald O. King, Qingfeng Tang, John Nantz, Douglas C. Campbell, Riad Ghabra
  • Patent number: 6308054
    Abstract: In the conventional diversity reception, information included in each non-selected signal does not contribute to an improvement in the reliability of communications, and transmitting power has been dissipated to satisfy required communication quality. Owing to the setting of encoding in respective base stations to injection, signals each including the same contents, which are received by a mobile station, are used for increasing the reliability of communications without depending on the number of the signals which were capable of being received by the mobile station, to thereby reduce transmitting power for satisfying required communication quality.
    Type: Grant
    Filed: December 19, 2000
    Date of Patent: October 23, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Atsushi Ogino, Hideya Suzuki, Tomoaki Ishifuji
  • Patent number: 6289036
    Abstract: There is provided a spread spectrum communication apparatus comprising a reception means for receiving a wide-band spread spectrum signal, a wave detection means for performing wave detection on a predetermined narrow-band signal within the reception signal received by the reception means, and a de-spread means for de-spreading the wide-band spread spectrum signal received by the reception means. Therefore, a desired one of a plurality of antennas to be used in a spread spectrum communication can be quickly and accurately selected, and also transmission power of the spread spectrum signal can be quickly and accurately controlled to have a desired value, whereby reliability of the spread spectrum communication can be increased.
    Type: Grant
    Filed: February 19, 1997
    Date of Patent: September 11, 2001
    Assignee: Canon Kabushiki Kaisha
    Inventors: Katsuo Saito, Atsushi Takasaki
  • Publication number: 20010011008
    Abstract: An apparatus for controlling the reception of electronic digital signals, which could include internet signals as a function of the location of a receiver for receiving said internet signals and further as a function of the signal strength of a terrestrially broadcast television signal at said location of the internet receiver is disclosed. In one embodiment, a GPS receiver and a radio receiver are utilized to control the reception at the location.
    Type: Application
    Filed: March 12, 2001
    Publication date: August 2, 2001
    Inventors: Jack Perry, David J. Cechota, Kenneth A. Franken, Toufic T. Moubarak
  • Patent number: 6246867
    Abstract: To solve the problems associated with conventional signal strength measurements utilizing homodyne receivers, the present invention is able to economically reduce the idle time power usage of a homodyne receiver by “powering down” a part of the homodyne receiver. With certain signal modulations, the power received in each channel of the homodyne receiver is equivalent and, as a result, the estimated received signal strength measurement calculation is simplified, reducing the power usage, which can be very useful, especially in the mobile communications industry.
    Type: Grant
    Filed: November 17, 1998
    Date of Patent: June 12, 2001
    Assignee: Telefonaktiebolaget LM Ericsson (publ)
    Inventor: Peter Jakobsson
  • Patent number: 6195399
    Abstract: A wideband radio receiver provides a complex baseband signal by normalizing an IF signal using a limiting amplifier. The normalized IF signal is applied to a complex sampling circuit to provide normalized I and Q components. The limiting amplifier provides an RSSI signal representing the received signal amplitude. The RSSI signal, which is sampled at the same rate as the normalized IF signal, is combined with the normalized I and Q components, to provide I and Q components of the baseband signal.
    Type: Grant
    Filed: July 24, 1997
    Date of Patent: February 27, 2001
    Assignee: Ericsson Inc.
    Inventors: Paul W. Dent, Rajaram Ramesh, Gregory E. Bottomley, Richard H. Myers
  • Patent number: 6157812
    Abstract: Systems and methods for improved use of idle power of each satellite repeater/transponder during low-traffic periods improve the overall link performance in multi-carrier, demand-assigned satellite communication systems through dynamic control and allocation of additional power to all signal carriers passing through each repeater when the total traffic load in the repeater is below a threshold. For satellite systems already in operation, the invention can be implemented and integrated into the existing feeder earth stations. For new systems, the invention can be implemented and integrated into the transmit section of individual satellite repeaters/transponders. The invention can be applied to new satellite systems to directly reduce the required satellite payload power for a given mission, thus substantially lowering the cost of the space segment.
    Type: Grant
    Filed: October 6, 1997
    Date of Patent: December 5, 2000
    Assignee: Hughes Electronics Corporation
    Inventor: Jamal Sarraf
  • Patent number: 6154451
    Abstract: In a multi-mode dual channlel data link there is provided a method for automatically controlling or allocating a predetermined amount of power to each of the dual channels. Two diverse product signal are transmitted from a master station down link to a plurality of ground stations. The ground stations receive the diverse product signals and individually determine the integrity of each product signal and transmit the product integrity information and a station identifier back to the master station. The master station processes the integrity information and reallocates a predetermined percentage of total power to be transmitted from each of the dual channels to achieve a predetermined product integrity at one or more of the plurality of ground stations.
    Type: Grant
    Filed: June 29, 1998
    Date of Patent: November 28, 2000
    Assignee: Northrop Grumman Corporation
    Inventors: John Walter Zscheile, Jr., Bruce John Weber
  • Patent number: 6151372
    Abstract: A diversity receiver is disclosed with an object to improve deteriorated transmission due to fading even when frequency selective fading resulting from multipaths occurs in a propagation path. The diversity receiver is provided with two lines, each line comprising an antenna, an orthogonal detector, first sampling and quantizing means, second sampling and quantizing means, a serial-parallel conversion circuit, and a Fourier transform circuit. In each of the lines, a modulated signal transmitted from a transmitter is received and processed. In a diversity processing unit, optimal diversity processing for each subcarrier is performed using the received and processed signals in respective lines. In this manner, an improvement is made in deteriorated transmission quality due to multipath fading between the receiver and the transmitter for transmitting OFDM modulated signals.
    Type: Grant
    Filed: July 15, 1999
    Date of Patent: November 21, 2000
    Assignee: NEC Corporation
    Inventor: Takeshi Yamamoto
  • Patent number: 6151508
    Abstract: The present invention discloses a method for improving a call quality by increasing the output of a mobile station over the reverse link by adjusting threshold range of a system's predetermined E.sub.b /N.sub.o value in the event that the transmission output of the mobile station is stopped in a reverse power control of a cellular system, and by comparing the measured E.sub.b /N.sub.o ratio to a predetermined threshold E.sub.b /N.sub.o ratio to increase/decrease the mobile station transmit power. The method includes steps of adjusting the predetermined threshold E.sub.b /N.sub.o ratio by monitoring the call quality in a forward frame, and repeatedly increasing/decreasing the mobile station transmit power accordingly.
    Type: Grant
    Filed: September 11, 1999
    Date of Patent: November 21, 2000
    Assignee: SamSung Electronics, Co., Ltd.
    Inventors: Gun-yeob Kim, Pyeong-hwan Wee
  • Patent number: 6151487
    Abstract: A demodulator and demodulating technique is provided which automatically switches modes according to the flat-fading or multipath channel status of an incoming signal. If an incoming signal has delay spread in addition to fading a standard Maximum Likelihood Sequence Estimator (MLSE) equalization is selected as an optimum demodulation mode. If the incoming signal is only flat-fading a symbol-based demodulation mode is selected. The Maximum Likelihood Sequence Estimator (MLSE) equalizer mode is thus integrated with the symbol based mode. Channel status is first identified in order to do mode selection in the demodulator. A dual-mode receiver for demodulating both flat-fading and multipath signals in a communications system (FIG. 1) comprises a Baseband Digital Signal (DSP) Processor further comprising a Channel Identification Processor, the Channel Identification Processor computing a Maximum Likelihood Sequence Estimate x=(x.sub.0 x.sub.1).sup.
    Type: Grant
    Filed: August 31, 1999
    Date of Patent: November 21, 2000
    Assignee: Hughes Electronics Corporation
    Inventors: In-Kyung Kim, Wonjin Sung
  • Patent number: 6147981
    Abstract: A method and apparatus for controlling a power level of a transmitted signal sent from a second station to a first station in a communication system maintains a desired power level of a signal received at the first station. The first station sends a power control command to the second station directing the second station to either increase or decrease the power level of the transmitted signal. The first station generates the power control command based on the power level of the received signal, the desired power level, and at least one pending power control command. Pending power control commands include those power control commands that are propagating between the first station and the second station.
    Type: Grant
    Filed: August 7, 1997
    Date of Patent: November 14, 2000
    Assignee: Qualcomm Incorporated
    Inventor: Tobin A. Prescott
  • Patent number: 6141534
    Abstract: A communication satellite system dynamically allocates additional downlink resources on the satellite to selected downlink signals to compensate for signal degradation. A typical cause of such degradation is rain where the downlink station is located. Another cause of such degradation is increased communication traffic or bandwidth demand within a particular region.
    Type: Grant
    Filed: March 25, 1998
    Date of Patent: October 31, 2000
    Assignee: Spacecode LLC
    Inventors: William L. Snell, Mark D. Thompson
  • Patent number: 6141536
    Abstract: An RDS receiver having dual tuners and dual antennas operates in two distinct modes, a diversity mode and a non-diversity mode. Diversity mode is when both tuners are tuned to a signal with the same program audio content and the audio from both tuners is blended together in a manner to minimize the effects of multipath distortion. In non-diversity mode, a forcing circuit isolates the tuner output signals so that one tuner provides the audio output while the other can be retuned to any other frequency for purposes of gathering RDS data.
    Type: Grant
    Filed: June 23, 1998
    Date of Patent: October 31, 2000
    Assignee: Visteon Global Technologies, Inc.
    Inventors: Milan Cvetkovic, David John McCall, Martin Gerard Page
  • Patent number: 6134423
    Abstract: A method and system wherein a system gateway (18) determines, from closed loop power control information, a power density at an antenna (13a) of a user terminal 13. The gateway also maintains a record of a duration of time that the power density exceeds a specified threshold. The gateway determines if an averaged transmitted power density associated with the antenna of the user terminal will equal or exceed at least one of a predetermined threshold level, within a specified period of time, or an absolute threshold level. If the gateway determines that a threshold will probably be exceeded if the call connection is maintained, the gateway terminates the connection prior to a time that the user terminal averaged transmitted power density level equals or exceeds the predetermined or absolute threshold level. A tone or a visual indicator may be employed to warn the user that a current connection or call will be terminated. Provisions are made for allowing predetermined types of calls (e.g.
    Type: Grant
    Filed: December 23, 1997
    Date of Patent: October 17, 2000
    Assignee: Globalstar L.P.
    Inventors: Robert A. Wiedeman, Paul A. Monte, Michael J. Sites
  • Patent number: 6127972
    Abstract: In a base station for providing wireless cellular service, an antenna arrangement is employed to transmit information to Mobile terminals, e.g., cellular radiotelephones, in a cell. The cell is divided into sectors. The antenna arrangement includes a number of antennas, each of which is used to serve one or more of the sectors. However, transmission of an antenna to a sector corresponding thereto is interfered by transmissions of other antennas to their corresponding sectors. To reduce such inter-sector interference in each sector, each antenna is designed to maximize beam efficiency of the sector, which is defined as a ratio of the power transmitted to the sector by the corresponding antenna to the total power radiated from the antenna.
    Type: Grant
    Filed: April 29, 1998
    Date of Patent: October 3, 2000
    Assignee: Lucent Technologies Inc.
    Inventors: Dan Avidor, Ashutosh Sabharwal
  • Patent number: 6125260
    Abstract: A method is for defining a radio frequency map to be used to isolate negative effects of undesirable radio frequency emitters on radio device communications, handheld and stationary. The method includes the steps of measuring C-band power corresponding to an L-band beam as part of an L-band footprint of a communication satellite, calculating various identifiable interference errors associated with the signal transmission path, and subtracting the interference errors from the original C-band power measurement resulting in a power value corresponding to undesirable radio frequency emitter interference at the location of the L-band beam. The resultant radio frequency map can then be used to reallocate frequency channels of operation used by radio devices, mobile phones for example, resulting in power savings in the radio device while maintaining a suitable signal-to-noise ratio.
    Type: Grant
    Filed: October 9, 1998
    Date of Patent: September 26, 2000
    Assignee: Globalstar, L.P.
    Inventors: Robert A Wiedeman, Vijaya K Gallagher, John A Serri
  • Patent number: 6108548
    Abstract: A mobile station is provided which does not cause a reduction in the speech transmission capacity. Branches receive radio signals from base stations and operate independently of one another. A branch operation control section controls the operation of the individual branches to detect a destination-side base station based on the reception levels of signals from surrounding base stations, to cause part of the branches to establish synchronization of spreading code and carrier frequency with respect to the destination-side base station while causing the other part of the branches to maintain communication with a departure-side base station after the destination-side base station is detected, and to cut off the communication with the departure-side base station after the synchronization is established.
    Type: Grant
    Filed: August 28, 1997
    Date of Patent: August 22, 2000
    Assignee: Fujitsu Limited
    Inventors: Hideto Furukawa, Yasuyuki Oishi, Kazuo Nagatani, Yoshiharu Tajima, Hidenobu Fukumasa
  • Patent number: 6097752
    Abstract: A satellite communication system (10) includes at least one satellite communication signal repeater (12); at least one ground station (18) for transmitting a feeder link comprised of a plurality of communication signals to the at least one satellite communication signal repeater; and a plurality of user terminals (13) each receiving one of the communication signals over a user link from the at least one satellite communication signal repeater. The satellite communication system further includes a closed loop power control system (80) having a plurality of inner loops (84), individual ones of which operate to compensate one of the user links for communication signal impairments occurring at least between the user terminal and the at least one satellite communication repeater, and an outer loop (82) which operates to compensate all of the user links for feeder link impairments occurring between the at least one ground station and the at least one satellite communication signal repeater.
    Type: Grant
    Filed: April 4, 1997
    Date of Patent: August 1, 2000
    Assignee: Globalstar L.P.
    Inventors: Robert A. Wiedeman, Michael J. Sites
  • Patent number: 6091934
    Abstract: The new signal amplifiers dynamically adjust based on the signal's power level. When used on multi-beam satellites, increased signal power indicates an increase in traffic on the channel. The power level of the input signal is sensed and converted to a DC signal, which is applied to a control terminal of a power supply that regulates DC power supplied to the amplifier. During periods of increased traffic, an increase in system power is allocated to the channel. By monitoring traffic on a plurality of channels, available onboard power is allocated based upon the relative channel requirements. The sensed power of multiple channels is summed and scaled to determine the power requirement of the channel relative to the other channels. A command voltage received from a ground station may be switched in place of the summed voltage to allow amplification levels to be controlled from the ground station.
    Type: Grant
    Filed: September 2, 1997
    Date of Patent: July 18, 2000
    Assignee: Hughes Electronics Corporation
    Inventors: Arnold L. Berman, William W. Mayfield, Marvin R. Wachs
  • Patent number: 6088570
    Abstract: In a conventional Time Division Multiple Access (TDMA) wireless system, the specified distance between a mobile unit and the base transceiver system (BTS) cannot exceed predetermined distances because of time slot synchronization constraints. Furthermore, varying distances between mobile units and the BTS, as well as Rayleigh fading, caused by destructive interference effects between direct and reflected signals, create extreme signal strength variations in the initial uplink signal from the mobile stations. The use of spatially-diverse antennas for receiving uplink signals provides diversity gain and mitigates deep fades. Furthermore, selecting the stronger of the spatially-diverse uplink signals mitigates deep fades and reduces frequency usage in the backhaul frequency band. In this approach to extending TDMA system coverage, in-band translator components are located in the center of remote cells which would normally contain a base transceiver system (BTS).
    Type: Grant
    Filed: November 24, 1998
    Date of Patent: July 11, 2000
    Assignee: Airnet Communications Corporation
    Inventors: Michael A. Komara, Thomas R. Schmutz, Jeffrey W. Smith, Stephen J. Foley
  • Patent number: 6088573
    Abstract: The invention provides a transmission power control apparatus for a mobile radio satellite communication system which allows frame synchronization maintenance and synchronization acquisition of a receiving station and optimum transmission power control with a simple construction which does not effect complicated control. The transmission power control apparatus includes a transmission power control loop provided in each of a gateway station and a terminal/mobile station for controlling a transmission power of the station. The transmission level during transmission is monitored and compared with a preset transmission level to change over an average time for sampling of the error between the transmission levels to vary the response speed of the transmission power control loop. When the channel for current use is to be changed over from a signalling channel to a communication channel, the transmission power is controlled so that there is no trouble for continuous synchronization of the reception side.
    Type: Grant
    Filed: May 28, 1998
    Date of Patent: July 11, 2000
    Assignee: NEC Corporation
    Inventor: Hiroki Tsuda
  • Patent number: 6085072
    Abstract: A telephone system and a voice encoding/decoding method capable of reducing the consumed power by reducing the memory capacity of buffer and generating high-tone-quality voice. The system writes an input voice frame to an input buffer and eliminates the delayed disturbance in a voice signal from the input voice frame based on the output voice frame to execute echo-canceling, and decodes the received voice packet data, so that the boundary of input voice frames can be set before the boundary of output voice frames, at least, for the time necessary for the echo-canceling and decoding. Thereby, the output voice frame can always be written at the same time as the input voice frame written to the input buffer and the delayed disturbance in the voice signal can be eliminated from the input voice frame based on the output voice frame and, thus the high-tone-quality voice can be generated.
    Type: Grant
    Filed: April 11, 1997
    Date of Patent: July 4, 2000
    Assignee: Sony Corporation
    Inventor: Kozo Komiya
  • Patent number: 6085067
    Abstract: A system and method for controlling the transmission power of a user terminal in a satellite communications system of a type that includes a ground segment, comprised of at least one user terminal and at least one terrestrial gateway, and a space segment, comprised of a plurality of satellites in a non-geosynchronous earth orbit. The method includes the steps of (a) transmitting an uplink signal from the user terminal simultaneously to at least two satellites of the space segment and (b) receiving the uplink signal with each of the at least two satellites.
    Type: Grant
    Filed: February 23, 1999
    Date of Patent: July 4, 2000
    Assignee: Globalstar L.P.
    Inventors: Vijaya K Gallagher, Paul A Monte, Robert A Wiedeman
  • Patent number: 6081710
    Abstract: A satellite communications system operative with at least one existing terrestrial communication system for carrying traffic is described. The communication system has a plurality of satellites in earth orbits, each satellite including a battery for sourcing electrical energy. The battery has energy sourcing limits. Gateways, bidirectionally linked to the plurality of satellites are also provided. A computing center, linked to the gateways, has a traffic control means for allocating traffic to the gateways. The traffic control means has three parts a power demand model for computing a first traffic allocation of traffic for each satellite; a satellite battery performance model descriptive of the energy sourcing limits of the on-board batteries; and a control law for applying weights to the first traffic allocation by using the battery performance model to obtain a second traffic allocation for each satellite.
    Type: Grant
    Filed: July 10, 1997
    Date of Patent: June 27, 2000
    Assignee: Globalstar L.P.
    Inventors: Richard H. Sherman, Stephen Boyd, Delmer R. Schneider, Jr.
  • Patent number: 6078823
    Abstract: A multiple antenna cellular network communicates with a mobile station over a plurality of antennas. The antennas are arranged in a plurality of positions to customize a cell or cells. A transceiver is coupled to the antennas and configured to receive inbound information from the mobile station and transmit outbound information to the mobile station. A processor is coupled to the transceiver and configured to decode the inbound information and to encode the outbound information to communicate with the mobile station. In another embodiment, the antennas are similarly deployed to create a cell or cells. The transmit signal power is continuously modified to improve quality and to move the nulls so that a fixed location user can receive a high quality signal. Exemplary embodiments are provided for use with the Global Systems for Mobile Communication (GSM) protocol and can be applied to other digital technologies.
    Type: Grant
    Filed: January 3, 1996
    Date of Patent: June 20, 2000
    Assignee: Interwave Communications International Ltd.
    Inventors: David A. Chavez, Ian L. Sayers, Gerald F. Sage
  • Patent number: 6073011
    Abstract: A method of controlling communication satellite system capacity in a satellite-based cellular telecommunication system where two or more communication satellites provide coverage of a service region. Communication satellites are assigned to mobile cellular stations in a manner designed to minimize the maximum single-satellite power that is required for the communication satellites collectively to supply a specified number of transmissions to the service region. The service region may be divided into grids, where each grid is characterized by a number which is proportional to the average number of active mobile cellular stations. This information, in conjunction with a power utilization factor associated with each satellite/grid pair, is used to determine the assignments of the communication satellites to the mobile cellular stations.
    Type: Grant
    Filed: December 19, 1995
    Date of Patent: June 6, 2000
    Assignee: TRW Inc.
    Inventor: Michael Horstein
  • Patent number: 6072986
    Abstract: In a global satellite communication system (10) that provides antenna beams that move with respect to Earth's surface, gateways (22) send ring alerts directed to subscriber units (26) based on a list of antenna beams. The list of antenna beams is determined by a dot product between a subscriber unit's basis vector and antenna beam vectors. Ring alerts are transmitted in antenna beams when the dot product exceeds a predetermined threshold. Subscriber units listen for ring alerts in the same antenna beams of the list by calculating the list the same way the gateway calculates the list.
    Type: Grant
    Filed: July 31, 1997
    Date of Patent: June 6, 2000
    Assignee: Motorola Inc.
    Inventors: Scott David Blanchard, Dean Paul Vanden Heuvel, Joseph Olk Lester
  • Patent number: 6072985
    Abstract: A spacecraft cellular communication system (10) includes a spacecraft (12) with an antenna (12a) which produces multiple "spot" beams (20a, 20b, . . . ) for serving user terminals (16) lying in the footprints (20af, 20bf, . . . ) of the beams. The communication system is controlled by a network control center (NCC 18), which produces forward control signals (608, 611, 613). The forward control signals include high-margin (H) portions and lower-margin (LM) portions. In order to minimize the power required to transmit the forward control signals from the spacecraft, the number of forward control signal carriers is limited to one per antenna beam. In order to minimize the peak-to-average power requirement placed on the spacecraft power source (12s, 12pc), the high-margin portions (H) of the forward control signals of the various antenna beams are mutually offset in time or time-interleaved.
    Type: Grant
    Filed: August 12, 1998
    Date of Patent: June 6, 2000
    Assignee: Lockheed Martin Corp.
    Inventor: Lee D. Wismer
  • Patent number: 6070074
    Abstract: A method for enhancing the performance of a communications system is disclosed. The system generally includes an originating ground station (300) which produces error-control coded uplink signals and transmits the coded uplink signals to a satellite (310). The system also includes a destination ground station (326) which receives a downlink beam from the satellite (310). The method includes the steps of receiving uplink signals transmitted by an originating ground station (300) at a destination ground station (326) and determining a downlink channel signal quality indication (504) at the destination ground station (326). The method also includes the steps of measuring an error rate associated with at least a portion of a downlink beam at said destination ground station (326) and determining an operating point (506) relative to a desired performance curve (502) based on the signal quality indication (504) and the error rate.
    Type: Grant
    Filed: April 24, 1998
    Date of Patent: May 30, 2000
    Assignee: TRW Inc.
    Inventors: Eldad Perahia, Donald C. Wilcoxson, Chamroeun Kchao
  • Patent number: 6067449
    Abstract: Antenna selection control apparatus for a diversity antenna system including at least two antennas. The received power strength is measured from a selected antenna and compared with a reference power level. The reference power level is adjusted depending upon the signal to noise ratio of received signals, and if the selected antenna falls below the adjusted threshold another antenna is selected.
    Type: Grant
    Filed: December 10, 1996
    Date of Patent: May 23, 2000
    Assignee: Nokia Mobile Phones Limited
    Inventor: Michael David Jager
  • Patent number: 6064659
    Abstract: In a transceiver in a wireless communications system, data is transmitted from the transceiver to subscriber units, wherein each subscriber unit has a requested transmit power and an allocated transmit power, and wherein the allocated transmit power is based upon the requested transmit power. A request for an additional power allocation is detected, wherein such additional allocation causes a total requested power to exceed a maximum transceiver power. In response, allocated transmit power is limited for a minimum number of selected subscriber units needed to reduce a total transceiver transmit power below the maximum transceiver power.
    Type: Grant
    Filed: July 10, 1998
    Date of Patent: May 16, 2000
    Assignee: Motorola, Inc.
    Inventors: Kamyar Rohani, Mansoor Ahmed
  • Patent number: 6061547
    Abstract: A transmitting apparatus for use in non-geostationary satellites which allows compliance with the restrictions placed on PFD even when the Earth is located between the geostationary satellite and the non-geostationary satellite. The transmitting apparatus 10 for use in non-geostationary satellites having a transmitting section 16 which sends a transmitting signal to the geostationary satellite, comprises an Earth-sensing section 19 for detecting the presence of the Earth in the direction of transmission and a transmission direction-shifting section 20 for shifting the direction of transmission of the transmitting signal in response to detection of the Earth-sensing section 19 to prevent the Earth from being exposed to the transmitting signal. Instead of the transmission direction-shifting section 20, there may be used a power supply-suspending section which automatically suspends power supply to the transmitting section 16 thereby stopping transmission of the transmitting signal.
    Type: Grant
    Filed: July 15, 1998
    Date of Patent: May 9, 2000
    Assignee: NEC Corporation
    Inventor: Kenichi Ikebe