Abstract: An apparatus and method for using a variable loop gain in a double-loop power control system to control the power of a forward link signal sent by a gateway to a user terminal to compensate for fading in a wireless communications system. In one embodiment the invention includes the steps of detecting fast fading in the forward link signal and informing the gateway of the fast fading; and at the gateway, reducing the loop gain of the power control loop when fast fading is indicated. In another embodiment, the invention includes the steps of, at the gateway, detecting fast fading in a reverse link signal received from the user terminal and reducing the loop gain of the power control loop when fast fading is indicated.

Abstract: A method and apparatus for determining whether cargo is present in a freight car. The freight car has a proximal (“rear”) end with a loading door and opposing, distal (“front”) end. One or more transmitters and receivers are mounted inside the freight car at the front end, toward the car's ceiling. The transmitters/receivers are operated by a controller, which also functions to analyze data from the transmitters/receivers and transmit related reports to a remote monitoring site. During a prescribed time period, a transmitter generates an ultrasonic signal pattern with a coverage area of prescribed radius that terminates before reaching the loading door. During the time period of transmission, or slightly later to account for signal reflection time, the controller operates the receiver to detect reflected signals originating from the transmitter.

Abstract: A mobile wireless telecommunications system includes base stations of a first type operating according to a first air interface, and base stations of a second type operating according to a second air interface. Methods and apparatus are provided for handing over a mobile station in the system from a first base station, which is of the first type, to a second base station, which is of the second type. A communications link is established over the first air interface between the mobile station and the first base station. Data is received from the mobile station responsive to a signal received by the mobile station over the second air interface from the second base station, substantially without breaking the communications link with the first base station. The mobile station is handed over from the first to the second base station responsive to the data received therefrom.

Abstract: A system and method for generating random numbers in a wireless communication network is presented. The noise present in the signal received by a wireless receiver is extracted to form random numbers. Wireless transmitters typically are identified by a synchronization signal. In acquiring the synchronization signal, a wireless receiver generates a plurality of psuedorandom sequences, despreads an incoming signal, integrates the resulting signal, and performs an energy computation to calculate an energy measure. One or more energy measures are collected in a pool of bits, and the bits are hashed to extract random numbers.

Abstract: Apparatus and method for paging a user terminal (UT) using a satellite communications system having a gateway and one or more satellites, wherein each satellite produces a plurality (n) of beams and each beam includes a plurality of channels. The method of the present invention includes the step of recalling a first location of the UT, wherein the first location corresponds to a location of the UT at a first time t1. In one embodiment, this is accomplished by performing a lookup in a table or database that includes location information for user terminals at different points in time. The method also includes the step of determining a first group (g1) of beams which covers the first location of the UT at a second time t2, where g1<n and time t2 is later in time than time t1. A page is then sent from the gateway to the UT on a channel, such as a paging channel, of at least one beam of the first group of beams. In one embodiment, the page is sent on the paging channel of each of the first group of beams.

Abstract: A mobile telephone has an existing configuration and displays a menu. The mobile telephone generates a time-out from the menu if an elapsed time after entering the menu exceeds a time period. In response to the time-out, the mobile telephone implements a new configuration based on the menu in which the time-out occurred.

Abstract: A method for reducing the number of required frequency and time hypotheses to acquire an access transmission in a satellite communication system. By reducing the number of required hypotheses, the amount of hardware required to acquire the access transmission is reduced. The method of the present invention reduces the number of required hypotheses by reducing the range of possible frequency and timing values of the access transmission. The range of possible frequency and timing values is reduced by determining the frequency and time uncertainties over individual satellite beams rather than over an entire satellite footprint.

Abstract: The present invention comprises a system and method for gain control of individual narrowband channels using a wideband power measurement. The present invention comprises a transmit power tracking loop which controls the power of the transmitted signal by controlling the gain applied to the signal. The function of the transmit power tracking loop is to measure power, accept commands for power adjustment, and adjust the power. Gain control is performed by producing an error signal using the comparison of measurements of a total of estimated powers of each narrowband signal and a measurement of the modulated wideband signal. In addition, open loop control is performed by accepting open loop commands generated by an algorithm.

Abstract: An improved method for determining the location of a user terminal with a high degree of accuracy. By repeating N times the basic active positioning measurement sets, a much better accuracy is reached that will be of value to the user. According to the method of the present invention, the user makes a position call. A position call prompts a gateway to establish a traffic channel on which a positioning message will yield the basic set of measurements: round-trip delay and round-trip Doppler in single-satellite positioning, and the addition of delay-difference and Doppler difference to a second satellite in two-satellite positioning. The accumulated measurements are used to determine position and theoretical error. The call is terminated when an accuracy threshold is reached or a time limit has expired. The user terminal receives a position message or a failure message.

Abstract: A system and method for adaptively controlling the encoded data rate in a data compression system. The system and method sets up alternative encoded bit streams for each segment of data and selects the alternative that would produce the bit rate closest to a predetermined target bit rate for transmission. Each segment of video input is quantized based on a set quantization settings to produce a plurality of quantized segments. Each quantized segment is then variable rate encoded to produce an alternative encoded bit stream. The data rate that would be required to transmit each alternative encoded bit stream is determined and compared with a predetermined target bit rate, which is set according to the transmission rate buffer status. The selected encoded bit stream is provided to the transmission rate buffer in preparation for transmission. Having processed one segment of data, the system and method then updates its parameters for processing the next segment of data.

Abstract: A system and method for determining a round trip delay of signals transmitted between first and second objects, such as a satellite and a mobile telephone, that move relative to each other. A first signal is transmitted from the first object to the second object. The first signal is received at the second object after a propagation delay D1, the delay D1 being the time taken by the first signal to traverse from the first object to the second object. A frequency of the first signal is measured at the second object. The second object then transmits to the first object a second signal containing a report of the measured first frequency. The second signal is received at the first object after a propagation delay D2, D2 being the time taken by the second signal to traverse from the second object to the first object. The first object measures a frequency of the second signal.

Abstract: A system and method for the detection of zero-rate communication frames on forward and reverse communication links is described herein. In a first embodiment, the rate determination process begins upon receiving pilot and traffic channel signals. The system then compares the received traffic channel energy with the pilot signal to obtain a metric. The metric is then compared with a predetermined threshold to detect the presence of a zero-rate traffic channel frame. In a second embodiment, the process begins with the receipt of a reverse communication link frame having first and second portions. The system then detects the energy contained in the first and second portions. The system compares the detected energy in the first portion with the detected energy in the second portion to obtain a metric. The system then compares the metric with a predetermined threshold to detect the presence of the zero-rate frame.

Abstract: A system and a method for address assignments for wireless satellite telephone systems comprises one or more desksets (telephones) and a radio antenna unit (RAU). The desksets are connected to the RAU using an interface bus. In operation, a deskset initiates an address arbitration cycle by transmitting a request for an address to the RAU. The RAU acknowledges after it receives the request, and queries other desksets if the requested address is being used by other desksets. If no other deskset responds within a predetermined time period, the RAU grants the requesting deskset the address. If the requested address is being used, the deskset using the address informs the RAU, and the RAU rejects the request. The requesting deskset then requests a different address. If all available addresses are being used, the requesting deskset informs the user and shuts down. If two or more desksets transmit requests concurrently, there will be a collision. To resolve a collision, the desksets are divided into two sets.

Abstract: A dielectric resonator antenna having a resonator formed from a dielectric material mounted on a ground plane with a conductive skirt. The ground plane is formed from a conductive material. First and second probes are electrically coupled to the resonator for providing first and second signals, respectively, to or receiving from the resonator. The first and second probes are spaced apart from each other. The first and second probes are formed of conductive strips that are electrically connected to the perimeter of the resonator and are substantially orthogonal with respect to the ground plane. A dual band antenna can be constructed by positioning and connecting two dielectric resonator antennas together. Each resonator in the dual band configuration resonates at a particular frequency, thereby providing dual band operation. The resonators can be positioned either side by side or vertically. Further advantage is obtained by mounting the dual antenna stack within a radome.

Abstract: The information signals are transferred to end users, customers, or service subscribers using at least two signal sources, generally satellites, and polarized radiation. Two polarization modes are employed, with the preferred modes being left-hand and right-hand circularly polarized radiation, although other polarization modes may be employed. The total number of channels can be divided among the polarization modes and transferred to end users either through the use of polarization switching in the receivers to selectively switch between the satellites, or by switching elements in the satellites (sources) to switch between polarization modes used for transmission.

Abstract: A system and method for controlling transmitted output power of hand held wireless devices used with external antenna units. Transmit power of information signals is controlled in the hand held device by obtaining design specification parameters of the antenna unit, which includes an output power measurement of the information signal transmitting from the antenna unit, which may also be referred to as an outdoor unit. The output power measurement is used by the hand held device, to adjust the power of the transmitted information signal. The output power measurement is determined in the antenna unit by obtaining a digital output power measurement, modulating the power measurement, and transmitting the modulated measurement signal to the hand held device. The modulated measurement signal is received by a cradle supporting the hand held device, or the device itself and demodulated. The hand held device uses the measurement to adjust the transmit power of the information signal.

Abstract: A frequency tracking loop for a communication system using orthogonal Walsh modulation is provided. The frequency tracking loop includes a correlator (120), such as a fast Hadamard transformation device, and a discriminator (130). The correlator (120) produces a correlation vector (122) representing the result of correlating the input signal with each of a set of Walsh functions, with corresponding index values. The discriminator (130) produces a frequency error signal (ê) based on the correlator (120) output with the highest energy level and other correlator outputs whose indices are related to the index of highest energy correlator output by powers of two. The frequency error signal (ê) is generated by producing a cross product between the highest energy output and one or more of the other related correlator outputs. In further aspects, a filter (140) can be used to further shape the resulting error signal (ê) and form a frequency offset estimate signal ({circumflex over (f)}).

Abstract: A system and method for unambiguously determining the position of a user terminal (for example, a mobile wireless telephone) in a low-Earth orbit satellite communications system. The system includes a user terminal, at least two satellites with known positions and known velocities, and a gateway (that is, a terrestrial base station) for communicating with the user terminal through the satellites. The method includes the steps of determining a range parameter, a range difference parameter, and either or both of a range-rate parameter and a range-rate difference parameter. A range parameter represents a distance between one of the satellites and the user terminal. A range difference parameter represents the difference between (1) the distance between a first one of the satellites and the user terminal and (2) the distance between a second one of the satellites and the user terminal. A range-rate parameter represents a relative radial velocity between one of the satellites and the user terminal.

Abstract: A planar bandpass filter that comprises a substrate having a ground plane on one side and a plurality of resonators on the other side. Each resonator includes an elongated inductive portion and a capacitive portion. The elongated inductive portions are coupled through the substrate at the end opposite of the capacitive portion to the ground plane. The planar bandpass filter also includes a first tap and a second tap. The first tap is connected to a first elongated portion to serve as an input to the bandpass filter. The second tap is connected to a last elongated portion to serve as an output to the bandpass filter.

Abstract: The present invention represents an integrated antenna assembly comprising a cellular communications antenna and a satellite communications antenna. Such an antenna assembly can, therefore, be used for communications over either frequency range. A wireless telephone using this assembly can, therefore, operate with either a terrestrial cellular communications system or a satellite communications system. In a preferred embodiment of the invention, the satellite communications antenna is a quadrifilar helix antenna and the cellular communications antenna is a sleeve dipole. The whip portion of the sleeve dipole is positioned axially in the center of the quadrifilar helix antenna. This orientation permits operation in both the satellite and cellular frequency ranges without significant electromagnetic coupling.