Abstract: Disclosed are methods and apparatus to control the actions of a user terminal (UT) located at a remote location, possibly far from a gateway (GW), which has an interface to the Public Switched Telephone Network (PSTN) and/or to the Internet. The methods and apparatus provide for operation of a mobile satellite communication system having at least one gateway (GW), at least one user terminal (UT), and a constellation of satellites. The methods and apparatus allow access to the communication satellites by specifying an exclusion zone having a confidence limit (CL) associated therewith. The methods and apparatus selectively provide service to a UT depending on a determined location of the UT relative to the exclusion zone and on an estimated error (E) of the determined UT location, wherein location of the UT is determined by the UT, and transmitted to the GW, or location of the UT is determined by the GW.

Abstract: A mobile satellite telecommunications system is disclosed including at least one user terminal, at least one satellite in earth orbit, and at least a gateway bidirectionally coupled to a data communications network wherein a user terminal comprises a controller responsive to applications for selecting individual ones of a plurality of Quality of Service modes for servicing different application requirements.

Abstract: A code division multiplexing system for a link between components of a satellite communications system is disclosed where, using spread spectrum techniques, channel blocks are each spread by a pre-assigned orthogonal chip-coded waveform. The pre-assigned orthogonal chip-coded waveforms are each preferably chosen according to the origin and destination of the channel block. The channel blocks are each spread over an intermediate frequency and then upconverted such that their spreading bandwidth is equal, or approximately equal, to the allocated bandwidth of the particular link through which they will be transmitted. The channel blocks are spread so they each have the same, or approximately the same, center frequency as the allocated frequency spectrum of the link.

Abstract: A mobile satellite telecommunications system is disclosed comprising at least a user terminal and a satellite which is in earth orbit and at least a gateway bidirectionally coupled to a data communications network. The user terminal comprises a controller responsive to at least one criterion having been met for activating an indicator to inform a user of a potential for reduced user terminal performance.

Abstract: A satellite communication system includes a plurality of satellites, such as low earth orbit satellites, and a plurality of gateways. The satellite communication system is bidirectionally coupled to a terrestrial communication system through at least the plurality of gateways. The satellite communication system and the terrestrial communications system together form a data communication network having a plurality of nodes including source nodes, destination nodes and intermediate nodes. Multiple copies of a packet can coexist within the data communication network, and the packet and its one or more copies are routed, using at least in part satellite-resident routers and gateway-resident routers, over a plurality of different paths between a particular source node and a particular destination node. At least one duplicate copy of a given packet is simply not used during the execution of a packet reordering procedure in the destination node, or at an intermediate node.

Abstract: A satellite-based communications system and a method for operating a satellite-based communications system is disclosed. The system is of a type where communications between a user terminal and a gateway occur using an uplink band of frequencies between the user terminal to at least one satellite and in a downlink band of frequencies between the at least one satellite and the user terminal. The system includes first transceivers in the user terminal, referred to herein as a dual user terminal or dual terminal (10), for transmitting and receiving voice and data in the first and second bands of frequencies using a maximum data rate (e.g., a conventional MSS maximum data rate of 9600 Baud); and further includes second transceivers in the user terminal for transmitting and receiving data in the first and second bands of frequencies using a second data rate that exceeds the maximum data rate.

Abstract: A method is disclosed for operating a satellite communications system for coupling a user terminal to a data communications network.

Abstract: A method includes steps of (a) establishing a call connection between a terrestrial telecommunications network and a user terminal via a first gateway and at least one satellite, (b) while the call connection is established, selecting at least one further satellite, and (c) maintaining the call connection to the terrestrial telecommunications network via a second gateway, the least one further satellite, and the first gateway. The at least one further satellite is selected, at least in part, based on information transmitted from the second gateway to the first gateway through an inter-gateway communications link, and can be based on signal quality indications determined at the user terminal, signal quality indications determined at the gateway(s), or path gains calculated at the gateway(s).

Abstract: There is disclosed a method and an apparatus for extending the effective service regions of gateways and virtual gateways through a gateway-to-gateway diversity technique. The gateways are interconnected for providing user terminal traffic and signalling information between themselves at call setup and during a call.

Abstract: Disclosed herein is a method for operating a satellite communications system as well as a method for providing a larger effective gateway coverage area, and a system that operates in accordance with the methods. The methods include steps of (a) establishing a call connection between a terrestrial telecommunications network and a user terminal via a first gateway and at least one satellite; and (b) while the call connection is established, coupling the user terminal to the terrestrial telecommunications network via a second gateway and at least one further satellite. The step of coupling includes a step of conveying call speech or data information between the first gateway and the second gateway over an inter-gateway communications link. By so linking multiple gateways each gateway experiences an increase in its effective coverage area, as an on-going call can be continued even after a user terminal moves from a first gateway's coverage area into a second gateway's coverage area.

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: The teaching of this invention pertains particularly to satellite communications systems using GSO or NGSO satellites. This invention employs data derived from signals of various types to derive a mathematical model of propagation related attenuation-inducing events so as to plan system resource allocation to minimize an amount of power required to close communication links between user terminals and the satellites. Disclosed are methods for modelling gateway to satellite links, as well as methods for modeling the user terminal to satellite links. This invention overcomes the problems inherent in the prior art by providing a direct measurement of severe path attenuation potential.

Abstract: A method for operating a mobile satellite telecommunications system has steps of (a) providing a user terminal that is operable to simultaneously receive a communication signal from a gateway via a plurality of satellites; and, (b) at the gateway, selectively transmitting the communication to one satellite or a plurality of satellites each having a coverage area that includes a current location of the user terminal. The step of selectively transmitting includes a step of considering a plurality of factors, including a current reception state of the user terminal, a current state of satellite power of at least one of the plurality of satellites, and a predicted required state of satellite power of the at least one satellite. The current reception state of the user terminal is indicated by a received signal quality indicator, which in the preferred embodiment is expressed as the Frame Error Rate (FER).

Abstract: A method for determining whether a gateway will service a user terminal in a satellite communication system comprises the steps of (1) determining whether a position of the user terminal is ambiguous, and (2) if the position is ambiguous, then (a) determining whether a previous registration of a service provider for the user terminal matches a current service provider accessible via the gateway, and (b) if the previous registration matches the current service provider, then accepting the user terminal for service by the gateway. Alternate methods involve determining that the user terminal is at either of two ambiguous positions, and (1) determining whether both of the two ambiguous positions are within a service area of the gateway, (2) determining whether at least one of the two ambiguous positions is within a restricted area for which the gateway does not provide service, or (3) determining a parameter of a beam transmitted from the user terminal to a satellite of the satellite communication system.

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 satellite-based communications system and a method for operating a satellite-based communications system is disclosed. The system is of a type where communications between a user terminal and a gateway occur using an uplink band of frequencies between the user terminal to at least one satellite and in a downlink band of frequencies between the at least one satellite and the user terminal. The system includes first transceivers in the user terminal, referred to herein as a dual user terminal or dual terminal (10), for transmitting and receiving voice and data in the first and second bands of frequencies using a maximum data rate (e.g., a conventional MSS maximum data rate of 9600 Baud); and further includes second transceivers in the user terminal for transmitting and receiving data in the first and second bands of frequencies using a second data rate that exceeds the maximum data rate.

Abstract: Disclosed are methods and apparatus to control the actions of a user terminal (UT) located at a remote location, possibly far from a gateway (GW), which has an interface to the Public Switched Telephone Network (PSTN) and/or to the Internet. A computer generated and stored database of an area (referred to as a Confidence Polygon), a volume (referred to as a Confidence Volume), and/or a plane (referred to as a Confidence Surface) is used to establish a geometric shape located on the earth, above the earth or in space, or combinations thereof. In addition, there is assigned to these areas, volumes and/or planes a static or a variable value referred to as a Confidence Limit (CL) that can be compared to a value of an error (E) in a position location of the UT. The error signal can either be generated by the UT or by the GW.

Abstract: A user terminal (16) includes an RF transceiver (30) for transmitting modulated RF signals to a gateway (14) and for receiving modulated RF signals from the gateway via at least one satellite (112). The satellite may be a GEO or a non-GEO satellite. The user terminal further includes a signal processor (32) coupled to the RF transceiver for demodulating received RF signals to digital signals, an audio unit (90,92,94) for transponding speech signals with a user, and a plurality of encoders/decoders (2A,2B) and/or vocoders (82,84,86) between the signal processor and the audio unit for encoding and decoding speech signals passing to and from the audio unit. A first vocoder can be a variable rate vocoder, a second vocoder can be a fixed rate vocoder, where the fixed rate vocoder operates at an average data rate that differs from, e.g., is less than, an average data rate of the variable rate vocoder.

Abstract: A method for operating a communication system includes steps of: (a) receiving a call for a user terminal at a satellite system gateway, the call originating from another user terminal; (b) examining a database to determine if the called user terminal is located within a coverage area of the satellite system gateway; and (c) if yes, formulating a paging message and transmitting the paging message to the called user terminal via at least one satellite. Upon the called user terminal responding to the page, the method further: (d) establishes the call using satellite system resources, (e) designates one of the calling or called user terminals as a call manager for the duration of the call, and (f) makes a temporary assignment of satellite system resources to the call manager user terminal for use in managing the remainder of the call. The step of establishing the call includes a step of assigning at least an initial channel/circuit pair to each of the user terminals.

Abstract: A method is disclosed for operating a mobile satellite telecommunications (MSTS) system, as is a system that operates in accordance with the method. In a MSTS having at least one user terminal, at least one satellite in earth orbit, and at least one gateway bidirectionally coupled to a data communications network, in response to a determination that at least one criterion being met, an indicator of the user terminal is activated for informing a user of a potential for reduced user terminal performance. The least one criterion can include comprised of a number of satellites through which a communication between the user terminal and the gateway is conducted, such as an occurrence of there being only one satellite through which the communication between the user terminal and the gateway is conducted, or a prediction of an occurrence that there will be only one satellite through which the communication between the user terminal and the gateway will be conducted.