Abstract: An integrated satellite/cell system and equipment that provides low-cost telephony services to remote/rural and other previously non-served areas. Local communications is through wireless cell technology with inter cell communication between cells and between cells and the public switched telephone network supported through existing, non-processing satellites by means of satellite earth terminal stations at the remote sites. A demand assigned multiple access satellite network controlled through a open channel signaling and data provides single-hop, full mesh connectivity. The cell can be any cellular or cordless phone technology.

Abstract: A user terminal provides communications to and from a radiotelephone communications system. This radiotelephone communications system supports communications with the user terminal at a first power level and paging to the user terminal at a second power level greater than the first power level. In addition, a page includes an indication when voice mail has been received at the radiotelephone communications system. In particular, the user terminal includes a transceiver, a processor, and a user interface. The transceiver receives communications from the radiotelephone communications system at the first power level, transmits communications to the radiotelephone communications system, and receives pages from the radiotelephone communications system at the second power level.

Abstract: Voice call group functionality is provided in a satellite based air traffic control system to allow air traffic controllers and pilots of one or more aircraft to establish and maintain voice communication over a group call. A pilot of an aircraft may maintain voice communication with the same air traffic controller the entire duration of the flight over the entire globe. Voice communication between the pilot of an aircraft may be handed off from one air traffic controller to another by switching voice call groups. The voice call group functionality allows an air traffic controller to communicate simultaneously with pilots of different aircraft, and also allows pilots of different aircraft to communicate with each other.

Abstract: The invention relates to establishing a connection in a satellite system. The base station continuously transmits information to the satellite for establishing a connection. The first terminal receives the reference and control carrier wave retransmitted by the satellite, whereafter the received information is used for selecting at least one frequency available for communication, and the selected frequency will be used for a desired connection with a particular terminal.

Abstract: A message processing center (140) is used in a global message delivery system. Message processing center (140) uses at least one GEO satellite (130) and at least one Non-GEO satellite (120) to delivers messages (pages) to a number of ground stations (110) located at various locations on the surface of the earth. Message processing center (140) determines loading for at least one GEO satellite (130) and at least one Non-GEO satellite (120). Message processing center (140) determines available capacity for at least one GEO satellite (130) and at least one Non-GEO satellite (120). Message processing center (140) uses a number of criteria to optimize the delivery of the message data.

Abstract: A method (1300) and apparatus (300) combines a terminal blockage profile for a ground-to-satellite terminal with satellite location and motion data for one or more satellites (12) in a satellite communication system (10) to predict an impending service outage or impairment on a real-time or near real-time basis and reports such impending outages or impairments, and the expected duration thereof, to the terminal operator. The prediction of an impending outage or impairment also can include analysis of information concerning atmospheric conditions in the vicinity of the terminal location as well as other potential sources of a service outage or impairment.

Abstract: A method for system acquisition for a subscriber unit (112) in a satellite communication system (100) maximizes life of a battery (320) of a battery-powered subscriber unit. A receiver (304) of the subscriber unit is energized only when ring bursts are expected from satellites in the system, serving to minimize consumption of battery power. During just two scans, the subscriber unit acquires enough information to enable it to identify the best beam for monitoring for a ring alert and to predict the nearby beams most likely to carry a ring alert targeted for the subscriber unit. From the received information, the subscriber unit can also perform necessary processes such as passive geolocation. The subscriber unit then enters a low-power standby mode, energizing the receiver only long enough to detect the best beam to scan for a ring alert targeted for the subscriber unit.

Abstract: A satellite (110 FIG. 1) is used to make channel allocations for SUs (120) in communications system (100). Satellite (110) operate within the confines of at least one subset of satellites. Satellites (110) allocate channels using a maximum cost list that is based on a cost function methodology. A list of potentially interfering antennas is determined using a cost function analysis. A list of active channels on each one the potentially interfering antennas is also established. Another list that includes a set of potentially interfering channels for each active channel is established. Cost functions are computed for each pair of active channels and its potentially interfering channels. These cost functions establish interference potentials for the available channels in the maximum cost list (400). Channels are allocated using the maximum cost list and interference potential thresholds. Cost functions are based on spatial isolation, spectral isolation, and temporal isolation.

Abstract: A satellite based broadcast data communications service for a satellite communications system is presented which allows a data information service provider (40) to send large blocks of data information to mobile subscriber units (50). A satellite gateway (30) is coupled to a service provider (40) via a ground link (42) and to a satellite communications network (10) via a gateway link (36). A mobile subscriber unit (50) is coupled to the satellite communications network (10) via both a message link (56) and a high-speed high-bandwidth downlink (58). The mobile subscriber unit sends a data request for requested data information to service provider (40) via message link (56), satellite communications network (10), gateway link (36), gateway (30), and ground link (42).

Abstract: A system for transmitting instructions from a master control facility (50) to a number of remotely located player units (11-14). The remotely located player units communicate through a mobile cell site (10). Cellular communication links (16) are provided to link the remote units (11-14) to cell site (10). Cell site (10) is linked to a satellite arrangement (20) via a communication link (21). The master control facility is linked to the satellite arrangement via communication link (23).

Abstract: Methods and systems for acquiring service for a user terminal with a satellite communications system are provided wherein geographic information is received via an electromagnetic transmission at the user terminal defining a location of the user terminal. A control channel is selected corresponding to one of the spot beams covering the location of the user terminal using the geographic information. The user terminal acquires service from the satellite communications system over the control channel. The geographic information enables the user terminal to shorten the search time by searching those channels which correspond to the geographic region determined from the geographic information.

Abstract: This invention discloses a network system including a plurality of access points, a multiplicity of network stations wherein for each station, a ratio between available channel fraction and station channel demand is defined, and wherein each of the multiplicity of stations roams between the plurality of access points so as to equalize the ratios over at least a subset of the multiplicity of stations

Abstract: A local traffic signal controller (3) is interfaced to a satellite subscriber unit (10) to provide for centralized control of the traffic signals (1) controlled by the local controller (3). A central controller (7) provides central control and can download program control information to local controller (3). Dial-up access to local controller (3) is provided to central controller (7) with the subscriber unit (10). The resultant communication path may be utilized to provide for accessing information from the local traffic signal controller (3). Such information may include indications of lamp failures, traffic pattern information and other status or traffic related information.

Abstract: An apparatus for providing a call interception capability includes a master call intercept database storing records of subscribers of a global mobile satellite communications system targeted for call interception by law enforcement agencies. The apparatus also has a visitor location register storing records of subscribers currently registered within a serviceable vicinity of a gateway earth station associated with said visitor location register. The apparatus further includes a target database storing records of registered subscribers targeted for call interception, and an intercept coordinator communicating with the master call intercept database and the visitor location register. The intercept coordinator stores in the target database a record of a targeted subscriber, when the visitor location register includes a corresponding record of the targeted subscriber.

Abstract: A communication system includes a spacecraft which produces a plurality of overlapping spot beams. The spacecraft moves periodically in the N-S direction. Terrestrial user terminals may lie in one spot beam when the spacecraft is in one position, and in another spot beam at a later time. The system also maintains a log of the spot beam location of the user terminals, so all the spot beams do not have to be polled to find the desired one. In order to avoid system loading by location updates resulting from spacecraft motion, the spot beam location of each user terminal is stored in paired form. When a particular user terminal is to be contacted, transmission is performed over both spot beams of the pair. Update occurs only if the user terminal is not in either spot beam of the pair.

Abstract: In a satellite communication system, a user terminal (11) seeks response from a selected earth station (7A-E) for a request for service based analysing the signal quality of broadcasts from earth stations (7A-E). Whichever earth station (7A-E) responds calculates which earth station (7A-E) can best meet the request for service. If it is another earth station (7A-E), the user terminal (11) is intructed to redirect the request for service thereto and, once in contact, the user terminal (11) addresses all new requests directly thereto, until the best earth station (7A-E) calculates that there is a better earth station (7A-E), and instructs the user terminal (11) to address all future requests for service thereto.

Abstract: In a mobile communication system, a system for providing communication between multiple users in a closed user group arrangement includes first and second mobile earth terminals (METs) registering with the mobile satellite system. The first MET selects a closed user group network identifier (NET ID) representing a NET group to establish voice communication therewith and transmits the NET ID to a central controller. The central controller receives the NET ID from the first MET, validates the first MET for communication, validates the NET ID, allocates a frequency for the NET group, and broadcasts the message to the NET group informing the NET group of the allocated frequency. The second MET tunes to the frequency in response to the message broadcast by the central controller. A full service dispatch (FSD) system monitors and displays detailed conference activity.

Abstract: In a mobile satellite system, a system for providing satellite communication between multiple users in a virtual network arrangement includes first and second mobile earth terminals (METs) responsively connected to and registering with the mobile satellite system. The first MET selects a virtual network identifier (VN ID) representing a virtual network group including the first and second METs to establish voice communication therewith and transmits the VN ID to a central controller. The central controller receives the VN ID from the first MET, validates the first MET for communication, validates the VN ID, allocates a frequency for the virtual network group, and broadcasts the message to the virtual network group including the second MET informing the virtual network group of the allocated frequency and the voice communication associated therewith. The second MET tunes to the frequency in response to the message broadcast by the central controller.

Abstract: The non-terrestrial cellular mobile telecommunication station uses a number of non-interference techniques to extend the usage of existing cellular mobile telecommunication radio frequencies allocated for ground-based communications to the non-terrestrial realm. For example, the polarization of the signals produced by the antenna elements of the non-terrestrial cellular mobile telecommunication station is different than and preferably substantially orthogonal to the polarization of the cellular radio signals produced by the ground-based antennas to thereby minimize the possibility of interference with the ground-based radio signals. Furthermore, the control signals exchanged between the non-terrestrial mobile subscriber stations and the non-terrestrial cell site controller are architected to avoid the possibility of interference with ground-based cell site transmitter-receiver pairs.

Abstract: A system and method for performing call handoff in a mobile communication system. The system is employed on commercial aircraft and enables cans to be transferred between different traffic service channels in order to continue and/or improve communications. In a conservation handoff scenario, user service channels are transferred between partially utilied traffic service channels resulting in unused traffic service channels that are released, thus freeing more traffic service channels for use by other aircraft. In a seizure handoff scenario, signal quality on one traffic service channel has begun to deteriorate prompting a call handoff wherein a call on the deteriorating traffic service channel is transferred to an unused user service channel on another traffic service channel already in use aboard the aircraft, thus allowing users to continue their calls.

Abstract: An elliptical orbit satellite system which describes communication and TT&C with ground stations. Earth stations are located for the circular orbiting satellite in a way such that the line of sight can never include geo synchronous satellites. The ground stations for the elliptically orbiting satellites monitor the position of the satellite, and no antenna communicates with a satellite which is in direct line of sight between the antenna and a geo satellite. Another aspect of the invention locates two TT&C stations, separated in longitude by 90.degree. and configures these stations such that each satellite in each constellation will be able to communicate with one of the two TT&C stations once during each satellite rotation period.

Abstract: Group communications between subscribers (20, 22) affiliated with a terrestrial communication system (12, 14) and subscribers (46, 48) affiliated with a satellite communication system (10) is begun when a subscriber has initiated a group communication request. The request is provided, via a controller (i.e., a terrestrial system controller or satellite system controller depending on which communication system the requesting subscriber is affiliated with), to a systems interface (36). Upon receiving the request, the systems interface determines whether subscribers that are identified to participate in the group communication are located in the terrestrial system and/or the satellite system. If the group of subscribers have members in both communication systems, the systems interface establishes satellite communication links for each subscriber affiliated with the satellite communication system and establishes a terrestrial communication link for subscribers affiliated with a terrestrial communication system.

Abstract: A method and apparatus have been described for combining multiple satellite constellations into a cooperative network. A GEO tier of satellites receives information to be broadcasted to earth. The GEO tier receives the information from global hubs, regional hubs, and local hubs. Local program material is combined with regional and global program material by either the regional hub or a GEO satellite.

Abstract: One embodiment of the present invention is a method for controlling the number of mobile-telephones transmitting acknowledgments to broadcast short messages (BSM) over a same set of random access channels at a same time. In this embodiment, the transmissions of BSM acknowledgments is controlled by the wireless communication system using random access channel restrictions and random access techniques. Specifically, the random access channel restrictions reduce collisions among acknowledging mobile-telephones and call processing mobile-telephones by allocating one or more specific random access channels over which a BSM acknowledgment can be transmitted, and the random access techniques reduce collisions among acknowledging mobile-telephones by distributing transmissions of the BSM acknowledgments over a period of time.

Abstract: A communication system and methodology are implemented to anticipate periodic or predictable disruptions of communications in a satellite communication network. The communication system and methodology then compensate for this disruption in an appropriate manner. Such prediction and compensation actions are performed for a selected group of subscribers ("premium" subscribers) who wish to originate or receive telephone calls during the period of time that the outage or disruption occurs. To compensate for such predictable outages, the communication network takes advantage of the multiple gateways typically implemented within mobile satellite communicate networks. Rather than using the multiple gateways for redundancy, the communication network and methodology recognize that the multiple gateways may also be used for the alternate routing of telephone calls, particularly during a period of time in which the outage occurs. Through this methodology, a "virtual routing" operation may be executed.

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.

Abstract: A direct-access satellite telecommunications system employs one or more telecommunications satellites in geosynchronous orbit. Small, low-cost user terminals are located at the user's premises and permit two-way telecommunications via user links. Access links provide satellite telecommunications to larger gateway stations as well as a network control center. Gateway stations store user information and provide connection to terrestrial telecommunications networks. In operation, the network control center allocates satellite bandwidth and power to setup the access and user links, with a minority of the satellite's power being allocated to the access links, and a majority of the power being available for the user links.

Abstract: A method and apparatus for autonomous assignment of communications channels during call handoffs by a user terminal in a satellite-based telecommunications system. The method comprises the steps of transmitting a request for access from a user terminal to a control center via at least one satellite and selecting channel parameters and model assignment information for a first communications channel at the control center. The assignment information identifies predictable events which require the first user terminal to switch to a second communications channel. The channel parameters and model assignment information are transmitted from the control center to the first user terminal. A communications link is established over a first channel with the first user terminal.

Abstract: A communication system and a method of providing a feeder link to an earth orbiting satellite transponder having a mobile link illuminating spot beams with associated access channels, control channels and traffic channels for multiple user terminals (UTs) using the satellite transponder as the reference point to correct for dynamic frequency errors including the Doppler in the feeder link and in the mobile link caused by the satellite motion and the satellite translation error. A satellite access node (SAN) includes one or several radio frequency terminals (RFTs) and a satellite basestation subsystem (SBS). The RFT performs the center Doppler correction for each of the channels of the feeder link to the satellite transponder. The SBS corrects the feeder link residual Doppler and the satellite translation error for each channel and calculates the Doppler in the mobile link between the satellite transponder and the median Doppler line of each spot beam on the earth or each UT.

Abstract: A satellite communications system comprises satellites 9A-C, earth stations 7A-E, user terminals 11 and controlling gateways 3 in the form of mobile satellite switching centers 5A-E. Access to and from a user terminal 11 may be gained from and to a terrestrial telephone system 1 by earth stations 7A-E contacting the satellites 9A-C and by the satellites contacting the user terminals 11. The satellites 9A-C periodically broadcast messages indicative of the earth station 7A-E with which they are instantly in contact. The user terminal 11 listens to these broadcasts, assesses the quality of the received signal, and keeps a league table based on an accumulated score allocated to each earth station 7A-E which can be heard. When calling into the system, the user terminal pages earth stations in descending order of score in the league table. When in contact, the user terminal 11 sends the league table to the system.

Abstract: A method for storing and retrieving telemetry which can reduce the size of a data storage tape and the time for retrieving data by overcoming the problems in a conventional satellite control system wherein all telemetry received from a satellite are stored without being subject to a filtering operation in a hard disk or memory of a computer for a predetermined time, and when needs arise for replaying previously stored data, a tape which stores required data is first located and mounted on a driver in order to load the required data. In accordance with the method of the present invention, data is filtered with respect to a variation of each telemetry. The data is stored step by step according to the period for which data should be stored. The data which should be stored for a long term is compressed and stored as an average value, maximum value, minimum value and variance of daily data. The generation and storage of long term data are offline processed.

Abstract: A method and system for providing global variable data rate connectivity in a satellite-based communications network includes a plurality of communications satellites for transmitting and receiving signals in a plurality of coverage areas. User terminals transmit and receive signals to and from the satellites. A set of the user terminals located in one of the coverage areas and associated with one of the communications satellites has a variable bandwidth associated therewith. The variable bandwidth is determined based on the collective bandwidth requirements of each of the user terminals in the set. Each of the user terminals may request a change in their bandwidth requirement independent of the variable bandwidth associated with the collective set of the user terminals.

Abstract: A cellular telephone network includes plural areas each having a plurality of cells. The cells individually supporting certain service capabilities. Inter-exchange messaging is provided for distributing from a second exchange to a first exchange information on the service capabilities supported by a cell serviced by the second exchange. Using the distributed service capability information, the first exchange may identify, in the context of a potential inter-exchange hand-off, whether to request that cells serviced by the second exchange be instructed to make verification signal strength measurements. Furthermore, responsive to received verification signal strength measurement reports, the first exchange screens candidate cells based on the distributed service capability information to select an appropriate target cell served by the second exchange for hand-off.

Abstract: In a method of handing off traffic in a low orbit satellite communication system serving terminals, a terminal being connected to a terrestrial communication network by means of a connection station, handing off of the satellite-terminal and satellite-connection station links is possible only within a particular area. The decision to hand off the traffic is based on deterioration of the quality of service and of the radio environment for a group of terminals of said area. The system for implementing this method includes transmit/receive terminals and terrestrial connection stations.

Abstract: A method is disclosed for adding a geostationary component (201) to a low earth orbit satellite network. The method includes establishing a geostationary orbit for an administration satellite, providing an East-West communications link (218) between a low earth orbit satellite (202) at a polar location and the administration satellite and providing an RF link (216) between a ground based network control center (214) on the ground and the administration satellite. The method also includes the steps of transmitting administration information received by the administration satellite over the RF link (216) from the administration satellite to the low earth orbit satellite (202) over the East-West communications link (218).

Abstract: The system allows a plurality of earth stations to communicate with one another by relaying transmission signals via satellites circling the earth in high earth and low earth orbits. A geostationary satellite operates in a geostationary orbit, while a plurality of low-earth orbiting satellites circle the earth in low-earth orbits. Those satellites serve as repeaters for the communications between a first earth station and a second earth station. Tracking relay means, disposed in the geostationary satellite, tracks only a limited number of low-earth orbiting satellites within an orbital range that corresponds to a predetermined area on the earth. Accordingly, the tracking relay means relays transmission signals of the second earth station to the low-earth orbiting satellites only when they are within the orbital range.

Abstract: Telecommunication services are provided to subscriber-provided radiotelephones (50) residing inside an aircraft (20). Telecommunication services are provided while the aircraft (20) is flying and utilize the aircraft's air-to-ground communication system (48) to access a radiocommunication link (34). Base stations (40) residing in aircraft (20) are configured to transmit at least two independent overhead control data pilot signals (54, 58) in response to instructions from a single controller (44). The control data pilot signals (54, 58) capture and control the subscriber-provided radiotelephones (50). Controlling methods are employed to force autonomous registration of radiotelephones (50) and to instruct radiotelephones (50) to transmit at minimum power levels.

Abstract: Radiated from each orbiting satellite of a satellite communication network to M cells (M representing an integer, such as thirty-seven) covered with a predetermined solid angle on the earth, M spot beams are identified by M identification codes. In an earth station which may be a portable unit, a burst signal transmitter device (31) comprises a receiver part (35) receiving one of the spot beams as a received beam at a reception time, to recognize as a recognized code one of the identification codes that identifies the received beam, and a transmitter part (45) for transmitting burst signals at a transmission time delayed from the reception time by an offset amount selected by the recognized code from M offset amounts predetermined for the identification codes. Preferably, the M offset amounts are stored in a memory (43).

Abstract: Additional resources and services are provided in a satellite communication system (100) through the use of seam satellites (52). One or more seam satellites (52) are coupled to communication satellites (12) in an existing constellation using previously unused crosslinks. The seam satellites (52) are located between orbital planes (31 and 36) in which the communication satellites (12) are moving in opposite directions with respect to each other. Seam satellites (52) can provide new services such as earth sensing and observation. Seam satellites (52) can also provide attachment points for other new space-based users. Some of the communication units (26) can communicate with the seam satellites (52) via communication satellites (12). This allows these communication units (26) to use the new services provided by the seam satellite (52). Seam satellites (52) can be controlled by separate control centers or can be controlled by the control center for the communication satellites (12).

Abstract: A satellite (S/C) cellular commsystem includes user terminals (UT) for transmitting to, & receiving signals from the S/C, and includes gateways for transmitting to the S/C. The gateways receive and distribute signals from the S/C. Each gateway identifies itself to a UT by use of a location area identity signal, including codes representing (a) the gateway residence country, (b) the system with which the gateway is associated, and (c) the antenna beam on which service is provided. A network controller (NC 18) transmits location area identity codes, representing (a) the identity of the S/C communication system, (b) the satellite carrying the control signal, and (c) the particular antenna beam on which the control signal is transmitted. The UTs store the location area identity signals, and further include a comparator for comparing the identity signals received from the NCC with the stored identity signals. If they are the same, no update is required. If they are different, the UT requests access from the NCC.

Abstract: An integrated telecommunications system provides fixed and mobile satellite-based services via one or more geosynchronous satellites. Two-way user links are provided by the satellites to user terminals located throughout a geographical region. Additionally, the satellites provide two-way access links to gateway stations within the region, and also to a satellite network control center. The network control center controls bandwidth and power of the satellites to establish the user links and the access links. A mobile cellular telephone network provides mobile cellular telephone service to a subscriber that also has a user terminal. A gateway station includes a gateway station controller coupled to a mobile switching center, which, in turn, is coupled to a terrestrial network. The gateway station controller provides control signals route calls to either the user terminal or the mobile cellular telephone of the subscriber based on a single dialed number.

Abstract: A system and method for providing two-way in-flight radio telecommunications on board an aircraft is disclosed. The radio telecommunication system includes a Gateway Mobile Switching Center (G-MSC), an Aircraft In-flight System Controller (AISC) located on board a subscriber's aircraft, a Ground In-flight System Controller (GISC), a satellite to relay messages and calls from the GISC and AISC, and a Home Location Register (HLR) which provides routing and location information for use by the GISC and the G-MSC. In an alternate embodiment of the invention, a system and method for using a mobile phone on an aircraft is disclosed. A mobile phone is connected to a seat terminal located on an aircraft by a co-ax cable. The radio frequency (RF) signals produced by a mobile phone pass through a coax cable to an Airborne Radio Base Station (A-RBS).

Abstract: The present invention relates to a means and a process of sharing a single system of ground stations between any number of satellite owners, permitting the owners to transfer command information to their satellite, and collect data streams that are sent back from the satellite all via a standardized global communications system maintained and operated by a commercial satellite communications company.

Abstract: A communication system is disclosed as including a plurality of mobile radio telephones, a control unit for transmitting a signaling message to an intended mobile radio telephone, and at least one paging channel through which the control unit is able to transmit the signaling message at varying margin levels. The control unit initially transmits the signaling message at a specified margin level for a predetermined number of attempts and progressively continues to transmit the signaling message at margin levels greater than the specified margin level until the intended mobile radio telephone receives the signaling message.

Abstract: A local telecommunications network is provided for satellite based telecommunications. The network 10 includes multiple handsets 18-22, 50 and 54 which communicate directly with ground stations 14 and 16. The ground stations communicate with an overhead satellite 12 through a satellite telecommunications uplink. The ground stations include a router for determining whether outgoing calls are directed to a destination handset located within or outside a predefined local geographic cell 30 and 32 for the corresponding ground station 14 and 16. If the destination handset is located outside the local cell of the originating handset, the ground station passes the call to the overhead satellite 12 to establish a satellite telecommunications link. However, if the destination handset 50 is located within the same local cell 32 as the originating handset 22, then the router 16 establishes a direct link between the handsets 22 and 50 without establishing a satellite telecommunications link 26.

Abstract: Methods and apparatus are disclosed which allow many satellites (A1-M, B1-N) in a plurality of Systems (A, B) to use the same radio frequencies (f1-n) so long as there is no interference between radio signals. The methods compute times (t) when satellite radio signals (32, 36) have overlapping reception areas or "footprints" (30, 35) on the Earth's surface (E) whereby a user's reception or transmission of a message would be interfered unless different frequencies (f1-n) are used for the "competing" signals. The methods use a timing algorithm that does not allow two satellites (Ai, Bi) which are "visible" at the same point on the Earth (E) to transmit on the same frequency (fi). In one preferred embodiment, a timing algorithm (48) produces a radio frequency use schedule (49) computed on the Earth from orbital data maintained in an ephemeris (46) of satellite communications systems (A, B) which communicate on frequencies (f1-n) giving rise to interfering radio signals.

Abstract: In satellite based communication systems (30), real time monitoring of communication links (23-25) and the subsequent adaptations to overcome problems with certain links (23,25) provides the communication system (30) with the ability to adapt to changing conditions. A satellite-based communication system (30) can be adapted to provide an improved method for establishing communication links (23,25) between ground stations (14) and space-based satellite switches (11). Common earth-based termination nodes are replaced by intelligent switches (14). Alternate links are established using links (20,21) between intelligent space-based switches (11), links (24) between intelligent earth-based switches (14), and links (23,25) between intelligent space-based switches (11) and intelligent earth-based switches (14). The controller (54) in the intelligent earth-based switch (14) allows the system to automatically adapt to failure, overload, and other conditions.

Abstract: A method and apparatus for handing off communications between a primary satellite system (500) and an alternate satellite system (550) determines (602) when a hand-off condition for the primary satellite system (500) exists. An alternate satellite (552) is determined (604, 904) which has a coverage area (554) which is positioned such that the alternate satellite (552) can provide an alternate communication link (556). A hand-off between the primary satellite system (500) and the alternate satellite system (550) is then performed (606). When the hand-off condition is alleviated (610), a hand-off back to the primary satellite system (550) is performed and normal operations are resumed (600).

Abstract: A control facility (130) within a wireless communication system receives, from a communication unit (120) (CU), a power measurement (306) of a signal (150) projected by a transceiver node (102). The power measurement (306) can be associated with location information (304) for the CU (120) and a time stamp (302). The control facility (130) uses this information to determine whether the CU (120) is being provided with a signal (150) having an acceptable link margin. If not, the control facility mitigates (408, 508, 512, 514, 518, 520) the effects of the unacceptable link margin, if possible. When power measurements (306) are received from multiple CUs (120), the control facility (130) can use the measurements (306) to create (402, 502) a link margin map which correlates CU location (304) with power measurements (306). The map is used to analyze the link margins within the system.

Abstract: A wireless telephone system capable of servicing a roaming wireless telephone user includes a satellite communications system consisting of one or more orbiting satellites, each carrying a database of users, destination codes and call codes, within a satellite service area, a satellite control center, and a plurality of terrestrial communications links.