Abstract: A satellite communications system (10) includes at least one satellite (12); a system controller (38); a plurality of gateways (18); and at least one user terminal (13) operable for bidirectionally communicating with at least one of the gateways through the at least one satellite. Individual ones of the plurality of gateways are bidirectionally coupled to at least one terrestrial communications system (4) and act to couple the user terminal to the terrestrial communication system through at least one satellite. In accordance with an aspect of this invention, individual ones of the plurality of gateways are operable for receiving an access request from the user terminal, through at least one satellite, and are further operable for notifying the requesting user terminal, through at least one satellite, that the user terminal is one of accepted by the gateway for establishing a communication link and not accepted by the gateway for establishing the communication link.

Abstract: A method for operating a satellite communications terminal (10) that transmits one of digital voice or data signals during a frame period. The terminal includes a transmitter and a receiver, the transmitter including an RF power amplifier.

Abstract: A method is disclosed for operating a first satellite communications system of a type that operates co-frequency with at least one second transmission system, such as a second satellite communications system. The method includes steps, executed during the operation of the first satellite communications system, of measuring at a plurality of locations within a coverage area of the first system an amount of interference resulting at least in part from the at least one second transmission system, the amount of interference being measured over a band of frequencies allocated to the first system; (b) transmitting an indication of the measured interference from each location to a central site; and (c) in accordance with the transmitted indications, assigning at least one user terminal to a sub-band of frequencies within the band of frequencies so as to reduce an amount of interference experienced by the user terminal.

Abstract: A method and system for accurately accounting for an amount of satellite communications system resources that are allotted to and utilized by a user terminal on a per call or connection basis. The method accumulates data at periodic intervals during a connection, the data indicating what portion of the overall system resources are utilized on both a forward link (gateway to satellite(s) to user terminal) and on a reverse link (user terminal to satellite(s) to gateway). The usage data can include power levels, data rates, user terminal location, and user terminal type. A Gateway (18) that is assigned to handling the call for the user terminal (13) accumulates the data and subsequently transfers the data over a terrestrial data network (39) to a Ground Operations Control Center (38). The center uses the data to determine an amount to be billed to a service provider associated with a service area that includes the gateway.

Abstract: A method and apparatus (system) for providing forward-link channel-frequency allocation for multiple-satellite cellular communications networks is disclosed. The system has a centralized ground-operations control center that provides bi-weekly minute-by-minute allocation plans for geographically-defined service areas. This enables each service area to set its diversity policy in accordance with the requirements of the government regulators and customer preferences within the service area. The system has a user model having a frequency re-use pattern, a channel allocation model for modelling the power allocated to each channel, and a gateway channel model for allocating channels in accordance with the user model and the channel allocation model. The allocation is made for each satellite of the plurality of satellites. The traffic allocation induces an operating frequency for each of the one or more links in each satellite of the plurality of satellites.

Abstract: Disclosed is a method and apparatus for enabling an authorized receiver station to decrypt encrypted information broadcast by a transmitter station, and for decrypting the information within the authorized receiver station. The method includes steps of storing a predetermined Subscription Key value in the authorized receiver station and, using the predetermined Subscription Key value, generating a Decryption Key value. In a next step the transmitter station broadcasts a signal which includes the encrypted information. After the broadcasted signal is received at the authorized receiver station, the authorized receiver station performs a predefined algorithm. The predefined algorithm uses the generated Decryption Key value to decrypt the encrypted information from the received signal.

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.

Abstract: A satellite communications system (10) includes at least one satellite (12); a system controller (38); a plurality of gateways (18); and at least one user terminal (13) operable for bidirectionally communicating with at least one of the gateways through the at least one satellite. Individual ones of the plurality of gateways are bidirectionally coupled to at least one terrestrial communications system (4) and act to couple the user terminal to the terrestrial communication system through at least one satellite. In accordance with an aspect of this invention, individual ones of the plurality of gateways are operable for receiving an access request from the user terminal, through at least one satellite, and are further operable for notifying the requesting user terminal, through at least one satellite, that the user terminal is one of accepted by the gateway for establishing a communication link and not accepted by the gateway for establishing the communication link.

Abstract: A satellite repeater system (10) provides a connection from satellites (12) to user terminals (14) that are located within a building. The satellite cellular repeater system receives satellite signals on a satellite receive antenna (18) and retransmits the received signal within a building using amplifiers (30) and indoor antennas (32). The system also receives signals from a user terminal, amplifies the signals, and retransmits the user terminal signals with an outdoor satellite antenna (20) back to a satellite. For a multi-story building each floor may be provided with a local transmit antenna (32), transmit amplifier (30), receive antenna (34), and receive amplifier (36) for conducting bidirectional communications with satellite telephones or user terminals that are present on that floor.

Abstract: A method 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.

Abstract: A communications system includes at least one low earth orbit first satellite (10), at least one second satellite (11) in other than a low earth orbit, and a ground segment (12) that includes a plurality of user transceivers (78, 80, 82, 84) and at least one gateway (76) coupled to a publicly-accessible terrestrial communications system, such as a PSTN and/or a fiber optic network. The first satellite includes a first transceiver for communication with the at least one gateway, a second transceiver for communication with at least one user transceiver, and a third transceiver for communication with the at least one second satellite. The first, second and third transceivers are switchably coupled together on-board the first satellite by on-board processors and a switching matrix for relaying a user communication between the at least one gateway and the at least one user transceiver via the at least one second satellite.

Abstract: A communication system includes a satellite communication system segment having at least one satellite, that projects a plurality of beams on the surface of the earth, and at least one terrestrial satellite gateway that is bidirectionally coupled to the at least one satellite and also to a terrestrial communications system. One or more beams from one or more satellites at the surface of the earth define a regional service area within which at least one Wireless Local Loop (WLL) service region is located. The communication system further includes a terrestrial communication segment having at least one WLL base station, capable of bidirectional communications with a plurality of WLL user terminals within the WLL service region, and a virtual gateway that is bidirectionally coupled to the WLL base station and to the at least one satellite.

Abstract: A method is disclosed for operating a first satellite communications system of a type that operates co-frequency with at least one second transmission system, such as a second satellite communications system. The method includes steps, executed during the operation of the first satellite communications system, of measuring at a plurality of locations within a coverage area of the first system an amount of interference resulting at least in part from the at least one second transmission system, the amount of interference being measured over a band of frequencies allocated to the first system; (b) transmitting an indication of the measured interference from each location to a central site; and (c) in accordance with the transmitted indications, assigning at least one user terminal to a sub-band of frequencies within the band of frequencies so as to reduce an amount of interference experienced by the user terminal.

Abstract: A satellite communications system (10) has a controller for improving and optimizing the delivery of path diversity in a satellite repeater-based communication system, thereby conserving both FDM channels and satellite power utilization. The reception of communications is improved, when one or more orbiting satellite repeater (12) transmitters is blocked or severely faded, by recognizing the need for satellite path diversity on a real-time or near real-time basis. A user terminal (13) is thus enabled to receive sufficient signal strength to avoid having an ongoing call automatically terminated. The system optimizes satellite path diversity applied to (a) classes (types) of user terminals and/or (b) to individual user terminals as a function of location and also a local RF propagation environment of the user terminal.

Abstract: A multi-path device includes a plurality of communication paths being defined between a plurality of first transceivers and one second transceiver. Each communication path contains at least one repeater. Each signal transmission from the first transceiver to the second transceiver contains an identifiable copy of an identical signal copy over each communication path. There is a signal quality determining portion associated with the second transceiver for determining the quality of the signal copy received by the second transceiver via each of said communication paths. A communication path limiting portion controls the strength of each communication path based upon said signal quality determining portion. It is envisioned that this device may use a CDMA communication protocol.

Abstract: A communication system (10), and a method executed by same, for allocating communications traffic through a plurality of satellites (12) of a constellation of low earth orbit satellites. Each of the plurality of satellites is oriented, at any given time when in view of a ground station (18), at a particular elevation angle. The method comprises the steps of: (a) providing each of the plurality of satellites with a receiver for receiving communication links from the ground station and a transmitter for transmitting communication links to user terminals; (b) in response to a request for service, determining if a highest elevation angle satellite can be assigned a new communications link; (c) if yes, assigning a new communication link to the highest elevation angle satellite; (d) if no, determining if a second highest elevation angle satellite can be assigned a new communications link; and (e) if yes, assigning a new communication link to the second highest elevation angle satellite.

Abstract: Disclosed are methods and apparatus for use in a satellite communications system (10) that enable a user to gain knowledge of a direction to one or more "best" satellites available to the user. This information enables the user to alter his or her position to take advantage of the one or more "best" satellites at any particular time in order to facilitate the ability to log-on, initiate and receive calls, and complete calls. The information can be supplied by the user terminal (13) itself, or by a gateway (14). The information can be employed by the user to select for a period of time, by example, a position on an east side of a building, to move to a south-east facing window, or to take some other action that enhances the user's connectivity to one or more of the satellites.

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.

Abstract: A multi-path device includes a plurality of communication paths being defined between a plurality of first transceivers and one second transceiver. Each communication path contains at least one repeater. Each signal transmission from the first transceiver to the second transceiver contains an identifiable copy of an identical signal copy over each communication path. There is a signal quality determining portion associated with the second transceiver for determining the quality of the signal copy received by the second transceiver via each of said communication paths. A communication path limiting portion controls the strength of each communication path based upon said signal quality determining portion. It is envisioned that this device may use a CDMA communication protocol.

Abstract: A method and apparatus for steering a low-earth-orbit communication satellite requiring sun-orientation for solar-power accumulation is disclosed. Momentum-bias both maintains nadir pointing and adds yaw-steering moments for sun-trackig attitude control, simultaneously. The method has two principal steps: 1) open-loop momentum decoupling, for correcting the calculated steering torque, and closed-loop attitude compensation, to correct for perturbations about the calculated attitude in accordance with one of two control law definitions. This combines the advantage of stable gyroscopic attitude control with those of open-loop yaw steering.