MXPA99008580A - Satellite communications system having distributed user assignment and resource assignment with terrestrial gateways - Google Patents

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 acceptedby the gateway for establishing a communication link and not accepted by the gateway for establishing the communication link. A gateway that does not accept a user terminal can indicate to the user terminal, based at least in part on a determined location of the user terminal, an identification of a gateway to which the user terminal should apply for access or log-in purposes. The system further includes a data network (39) that interconnects the system controller and the plurality of gateways. The data network may be conveyed by and embodied in one of a wired network, a wireless network, and a combination of a wired network and a wireless network.

Description

SATELLITE COMMUNICATION SYSTEM WITH DISTRIBUTED USER ALLOCATION AND ALLOCATION OF RESOURCES WITH LAND GATES FIELD OF THE INVENTION In general, this invention relates to satellite communication systems and, in particular, to resource allocation techniques for satellite communication systems.

BACKGROUND OF THE INVENTION The patent of E.U.A. commonly assigned number 5,448,623, issued September 5, 1995, entitled "Satellite telecommunication system using gateways for coordination of networks operating with a terrestrial telecommunication system", by R.A. Wiedeman and P.A. Monte, describes a wireless telephone system capable of serving a roaming wireless telephone user. The system includes a satellite communication system having at least one and preferably a constellation of satellites in orbit; at least one land-based gate that has access to the user database; at least one network coordination gateway in at least one satellite service area; a single network control center; and a plurality of terrestrial communication links. A terrestrial data network links the terrestrial-based components of the system and is used to communicate, for example, the control of the system and the information status between the terrestrial-based components. The system operates by communicating between a terrestrial wireless telephone end-user transceiver and a terrestrial communication link by means of a relay through a single satellite or a succession of satellites of a single relay. The relay satellite may be in motion with respect to the transceiver of the end user and the terrestrial communication link. The terrestrial base gate cooperates with the network database to effect a transfer of a first satellite in orbit to a second satellite in orbit. The satellites in orbit near the Earth only need to translate the signals of the gates and of the users to the gates without control based on the satellite; that is, the satellite functions to receive a transmission originating in the Earth from a gate of a user transceiver, translate the frequency of the received transmission, and transmit the translated frequency transmission back to Earth.

OBJECTIVE OF THE INVENTION It is an object of this invention to provide improvements to the satellite communication system described in the US patent. No. 5,448,623.

BRIEF DESCRIPTION OF THE INVENTION The above and other problems are overcome and the objective of the invention is realized by a satellite communication system having at least one satellite; a system controller; a plurality of gates and at least one user terminal operable to communicate bidirectionally with at least one of the gates through at least one satellite. Each of the multiple gates is bi-directionally coupled to at least one terrestrial communication system and acts to couple the user terminal to the terrestrial communication system through at least one satellite. According to one aspect of this invention, each of the multiple gates are operable to receive a request for access from the user terminal, through at least one satellite, and in addition are operable to notify the requesting user terminal, through at least one satellite, that the user terminal is one of those accepted by the gate to establish a communication link, or that it is not accepted by the gate to establish the communication link. In accordance with another aspect of this invention, each of the various gates is bidirectionally coupled to a database that indicates the identities of the active connected user terminals. The gates are operable to receive a connection request from a user terminal, through at least one satellite, and are also operable to notify the requesting user terminal, through at least one satellite, of: ( a) that the connection request of the user terminal was accepted by the gate to be stored in the database; and (b) that the connection request of the user terminal was not accepted by the gate. A gateway that does not accept a user terminal may indicate to it, based in part at a particular location of the user terminal, an identification of a gate or gates to which the user terminal must request access or connection intentions. In addition, the system includes a data network interconnecting the system controller and the plurality of gates. The data network is employed by the system controller and through the gates for some purposes, including the selective allocation of system resources to each of the multiple gates in part based on at least one predicted request for system resources. According to a further aspect of this invention, the data network is sent by and is comprised in a single wireless network and a combination of wired network and wireless network; for example, all or a part of the data network can be included in wireless links that are established between the gates through at least one communication satellite.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other characteristics of the invention are more apparent in the following detailed description of the invention when read together with the accompanying drawings, wherein: Figure 1 is a block diagram of a satellite communication system that is constructed and operated in accordance with the preferred embodiment of this invention; Figure 2 is a block diagram of one of the gates of Figure 1; Figure 3A is a block diagram of the communication payload of one of the satellites of Figure 1; Figure 3B illustrates a portion of the ray pattern that relates to one of the satellites of Figure 1; Figure 4A is a diagram of a first embodiment of a system data network that can be totally or partially included in the RF links that interconnect non-geosynchronous satellites and terrestrial gates; Figure 4B is a diagram of a second embodiment of a system data network that can be included totally or partially in the RF links interconnecting satellites and terrestrial gates, wherein at least one of the satellites is a geosynchronous satellite; Figure 5 illustrates a user terminal, three service areas, three satellite beams and three gates, and is useful in explaining a method of this invention; Figures 6A and 6B are a flow diagram illustrating a first method of this invention; Figure 7 is a flow chart illustrating a second method of this invention; and Figure 8 is a block diagram of a user terminal that is adapted to implement the teaching of this invention.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 illustrates a currently preferred embodiment of a satellite communication system 10 that is suitable for use with the preferred embodiment of this invention. Before describing this invention in detail, a description of the communication system 10 will first be made to give a full understanding of the present invention. Communication system 10, in concept, can be subdivided into a diversity of segments 1, 2, 3 and 4. Segment 1 here refers to a segment of space, segment 2 to a user segment, segment 3 to a segment to ground (terrestrial), and segment 4 to an infrastructure segment of the telephone system.

It should be noted that segment 3 to ground or terrestrial is intended to cover all components that are located anywhere or adjacent (including aircraft) to the surface of the Earth.

Any components that are located in or on bodies of water are then considered to be included in the terrestrial segment. In this preferred embodiment of the invention there is a total of 48 satellites in, for example, a Low Earth Orbit (LEO) of 1414 km. The satellites 12 are distributed in 8 orbital planes with 6 satellites separated by the same distance per plane (Walker constellation). The orbital planes are inclined at 52 ° to the equator and each satellite completes an orbit once every 114 minutes. This approach provides coverage to approximately the entire Earth, preferably at least 2 satellites in view at any time from a particular user location between approximately 70 ° south latitude and around 70 ° north latitude. As such, a user can communicate to or from almost any point on the surface of the Earth in a gate coverage area (GW) 18, to or from any point on the surface of the Earth (through the PSTN), through one or more gates 18 and one or more of the satellites 12, perhaps a portion of the telephone infrastructure segment 4 is also used. It should be noted at this point that the foregoing and the following description of the system 10 represents not only an appropriate mode of a communication system in which the teaching of this invention can be used.; that is, the specific details of the communication system will not be read or constructed in a limited sense in the practice of this invention. Next, in order to continue with a description of the system 10, a soft transfer procedure (transfer) between the satellites 12, and also between each of the light point rays 16 transmitted by each satellite (Figure 3B), provides uninterrupted communications by means of a extended spectrum (SS), code division multiple access (CDMA) technique. This preferred SS-CDMA technique is similar to the provisional TIA / EIA standard, "Station-based mobile station compatibility standard for dual-mode wide-band extended-spectrum cellular system" TIA / EIA / IS-95, July 1993, although other extended spectra and CDMA techniques and protocols may be used. In general, any multiple access scheme may be employed, such as CDMA, TDMA, FDMA, or a combination of such techniques. Low terrestrial orbits allow mobile or fixed low power user terminals 13 to communicate via satellites 12, each of which operates in this preferred embodiment of the invention only as a "curved tube" repeater to receive a signal of communication traffic (such as voice and / or data) of a user terminal 13 or of a gate 18, converting the received communication traffic signal to another frequency band, and then retransmitting the converted signal, i.e. that no resident signal processing of a received communication traffic signal occurs, and satellite 12 is unaware of any intelligent device to which a transmitted or received communication traffic signal may be sent. In addition, it is necessary that there is no direct communication link or links between the satellites 12; that is, each of the satellites 12 receives a signal only from a transmitter located in the user segment 2 or from a transmitter located in the segment 3 to ground, and transmits a signal only to a receiver located in the user segment 2 or to a receiver located in segment 3 to ground. The user segment 2 may include a variety of types of user terminals 13 that are adapted for communication with the satellites 12. The user terminals 13 include, for example, a variety of different types of mobile or fixed user terminals including, but not limited to mobile hand-held radiotelephones 14, mobile radiotelephones for vehicles 15, locator / message-type devices 16, and fixed radio telephones 14a. Preferably, the user terminals 13 have omnidirectional antennas 13a for directional communication through one or more of the satellites 12. It should be noted that the fixed radiotelephones 14a can employ a directional antenna. This is convenient because it produces a reduction in interference with a consequent increase in the number of users who can be serviced simultaneously with one or more of the satellites 12.

In addition, it should be noted that the user terminals 13 can be dual-use devices that include circuitry for communicating also with a terrestrial cellular system. Also, with respect to Figure 3A, the user terminals 13 can operate in a full-duplex mode and communicate by, for example, L-band RF links (uplink or return link 17b) and S-band RF links (link descending or forward link 17a) through the return and forward satellite transponders 12a and 12b, respectively. The RF links 17b of the return L band can operate on a frequency scale of 1.61 GHz to 1625 GHz, a bandwidth of 16.5 MHz, and are modulated with packet digital voice signals and / or data signals in accordance with the preferred extended spectrum technique. The RF forward links 17a of the S-band can operate on a frequency scale of 2.485 GHz to 2.5 GHz, a bandwidth of 16.5 MHz. The RF forward links 17a are also modulated on a gate 18 with digital voice signals of package and / or data signals according to the extended spectrum technique. The 16.5 MHz bandwidth of the forward link is divided into 13 channels up to, for example, 128 users assigned per channel. The return link may have various bandwidths and a given user terminal 13 may or may not be assigned to a different channel than the channel allocated in the forward link; however, when operating in the diversity reception mode in the return link (reception of two or more satellites 12), the user is assigned the same forward channel for each of the satellites and the same or a different channel for the return link. The ground segment 3 includes at least one gate 18, but in general, a plurality of them communicating with the satellites 12 by, for example, a full-duplex C-band RF link 19 (forward link 19a ( with the satellite), return link 19b (from the satellite)) operating on a frequency scale generally over 3 GHz and preferably in the C band. The C-band RF links send the communication feeder links bidirectionally and they also send the satellite commands to the satellites, as well as the telemetry information from the satellites. The feed link 19a can operate in the 5 GHz to 5.25 GHz band, while the return feeder link 19b can operate in the band from 6,875 GHz to 7,075 GHz. Preferably, the 12 g and 12 h link antennas of the satellite feeder are wide coverage antennas that depend on a maximum terrestrial coverage area as observed from the LEO satellite 12. In this preferred embodiment of the communication system 10, the dependent angle of a given LEO satellite 12 (assuming angles of elevation of 10 ° from the surface of the Earth) is around 107 °; this produces a coverage area that is approximately 6674 km in diameter.

The L-band and S-band antennas are multi-beam antennas that provide coverage in an associated terrestrial service region. The antennas of band L and band S 12d and 12c, respectively, are preferably congruent with each other, as shown in Figure 3B; that is, the transmission and reception rays of the spacecraft cover the same area on the surface of the Earth, although this feature is not decisive for the operation of the system 10. As an example, several thousand full-duplex communications can occur through of one of the satellites 12. According to a characteristic of the system 10, two or more satellites 12 can each send the same communication between a given user terminal 13 and one of the gates 18. This mode of operation, as it is described in detail below, therefore it is responsible for the diversity that is combined in the respective receivers, resulting in an increase in resistance to fade and facilitate the instrumentation of a soft transfer procedure. It should be noted that all frequencies, bandwidths and the like described herein are representative of only one particular system. Other frequencies and frequency bands can be used without any change in the principles presented here. As an example only, the feeder links between gates and satellites can use frequencies in a band other than the C band (around 3 GHz to 7 GHz approximately), for example the Ku band (around 10 GHz to 15 GHz approximately ) or the Ka band (above approximately 15 GHz). The gates 18 function to couple the communication payload or transponders 12a and 12b (Figure 3A) of the satellites 12 with the telephone infrastructure segment 4. Transponders 12a and 12b include an L-band receiving antenna 12c, S-band transmission antenna 12d, C-band power amplifier 12e, C-band low noise amplifier 12f, C-band antenna 12g and 12h, section 12i of conversion of band frequency L to band C, and section 12j of frequency conversion of band C to band S. The satellite also includes a master frequency generator 12k and telemetry and command equipment 121. Reference can also be made in this connection to the US patent No. 5, 422, 647 of E. Hirshfield and C.A. Tsao, entitled "Payload of mobile communication satellites", which describes a type of payload of communication satellites that is suitable for use with the teaching of this invention. Telephone infrastructure segment 4 consists of existing telephone systems and includes floodgates from Public Land Mobile Network 20 (PLMN), local telephone exchanges, such as regional public telephone networks (RPTNs) 22 or other local telephone service providers, long distance home networks 24, international networks 26, private networks 28 and other RPTN 30. The communication system 10 functions to provide bi-directional voice and / or data communication between user segment 2 and basic telephone network telephones 32 (PSTN, for its acronym in English) and telephones that are not PSTN 32 segment 4 telephone infrastructure, or other user terminals of various types, which may be private networks. Also, in Figure 1, as a portion of Segment 3 to land, there is a Satellite Operations Control Center (SOCC) 36 and a Ground Operations Control Center (GOCC, for its acronym in English). ) 38. A communication path, which includes a Data Network (DN) 39 (see figure 2), is responsible for the interconnection of gates 18 and TCU 18a, SOCC 36 and GOCC 38 of segment 3 to ground. This portion of the communication system 10 provides the general control functions of the system. Figure 2 shows one of the gates 18 in greater detail. Each gate 18 includes up to four dual-polarized RF-band subsystems C comprising a parabolic antenna 40, antenna controller 42 and pedestal 42a, low noise receptors 44, and high power amplifiers 46. All of these components can be located in a structure radome to provide environmental protection. The gate 18 further includes demodulators 48 and upconverters 50 for processing the received and transmitted RF carrier signals, respectively. The demodulators 48 and the upconverters 50 are connected to a CDMA subsystem 52 which, in turn, is coupled to the Basic Telephone Network (PSTN) through a PSTN 54 interface. As an option, the PSTN can be evaded using satellite links to satelite. The CDMA subsystem 52 includes a signal change / summing unit 52a, a Gate Transceiver Subsystem (GTS) 52b, a GTS 52c controller, a CDMA Interconnection Subsystem (CIS), English) 52d and a Selector Bank Subsystem (SBS) 52e. The CDMA 52 subsystem is controlled by a Base Station Manager (BSM), for its acronym in English) 52f and works similarly to a base station compatible with CDMA (for example, one compatible with IS-95). The CDMA subsystem 52 also includes the necessary frequency synthesizer 52g and a 52h Global Position System (GPS) receiver. The PSTN 54 interface includes a 544 Service Switch Point (SSP) of PSTN, a Call Control Processor (CCP) 54b, a Visitor Position Register (VLR), English) 54c and a protocol 54d interface with an Initial Position Register (HLR). The HLR may be located in the cellular gate 20 (Figure 1) or, as an option, in the PSTN 54 interface. The gate 18 is connected to the telecommunication networks through a standard interface, made through the SSP 54a. Gate 18 provides an interface and connects to the PSTN through a Primary Rate Interface (PRI) or other suitable means. In addition, gate 18 has the ability to provide a direct connection to a Mobile Communication Center (MSC). Gate 18 provides a fixed signaling SS-7 ISDN with CCP 54b. From the end of the gate of this interface, the CCP 54b interfaces with the CIS 52d and therefore the CDMA 52 subsystem. The CCP 54b provides protocol translation functions for the Air Interface (Al, for its acronym in English) of the system, which may be similar to the provisional standard IS-95 for CDMA communications. In general, blocks 54c and 54d provide an interface between gate 18 and an external cellular telephone network that is compatible, for example, with IS-41 (American Standard, AMPS) or GSM cellular systems (European Standard, MAP) and, in particular, with the methods specified for handling itinerants, that is, users who place calls outside the base system. Gate 18 supports authentication of the user terminal for 10 / AMPS system telephones and for 10 / GSM system telephones. In service areas where there is no telecommunication infrastructure, an HLR can be added to gate 18 and interface with the SS-7 signaling interface. The system 10 accommodates a user who makes a call outside his normal service area (a roamer), if authorized. In this itinerant, perhaps in any environment, a user can use the same terminal equipment to make a call from anywhere in the world, and the necessary conversations of the protocol are carried out with transparency through the gate 18. The protocol interface 54d is evaded when it is not necessary to convert, for example, GSM to AMPS. Within the scope of the teaching of this invention a dedicated universal interface is provided with the cellular gates 20, in addition to or instead of the conventional "A" interface specified for GSM mobile switching centers and distributor-owned interfaces with IS mobile switching centers -41. Furthermore, within the scope of this invention an interface is provided directly with the PSTN, as indicated in Figure 1, as the path of the signal designated PSTN-INT. Also, within the scope of this invention is provided one or more gates that are not connected to any cellular system and / or PSTN. The general control of the gate is provided by the controller of the gate 56 that includes a 56a interface with the Data Network (DN) 39 mentioned above and an interface 56b with a Service Provider Control Center (SPCC). in English) 60. The gate controller 56 is generally interconnected with the gate 18 through the BSM 52f and through the RF controllers 43 related to each of the antennas 40. The gate controller 56 is further coupled with a database 62, such as a user database, satellite calendar data, etc., and with a l / O 64 unit that enables service personnel to access the gate 56 controller. DN 39 also it has a bidirectional interface with a Telemetry and Commands 66 unit (T &C) (figure 1).

The function of GOCC 38 is to plan and control the use of satellites through gates 18 and coordinate that use with SOCC 36. In general, GOCC 38 analyzes trends, generates traffic plans, assigns satellites 12 and system resources (such as, but not limited to channel and power assignments), it monitors the performance of the general system 10, and issues instructions for the use of system resources by means of DN 39 to gates 18 in real time or in advance. The SOCC 36 works to conserve and monitor orbits, relaying information from satellites with the gate to output the GOCC 38 through the GDN 39, monitor the overall operation of each satellite 12, including the state of the satellite batteries, set the gain for the trajectories of the RF signal in satellite 12, guarantee the optimal orientation of the satellite with respect to the surface of the Earth, in addition of other functions. As described above, each gate 18 functions to connect a particular user to the PSTN for signaling, voice and / or data communications and also to generate data via a database 62 (Figure 2), for purposes of billing. The selected gates 18 include a Telemetry and Commands Unit (TCU) 18a for the reception of telemetric data that are transmitted by the satellites 12 via the return link 19b, and for the transmission of commands to the satellites 12, through the link of advance 19a. DN 39 works to interconnect gates 18, GOCC 38 and SOCC 36.

The DN 39 can be instrumented as a data network only terrestrial using cables and / or optical fiber. Also, within the scope of this invention all or part of the DN 39 is instrumented as a wireless link interconnecting the gates 18, also as a possibility the GOCC 38 and the SOCC 36, through the constellation of satellites 12. To this respect, reference can be made to Figure 4A, in which a plurality of gates 18 is interconnected through spatially based RF links that send the DN 39 via the satellites 12, while others are interconnected via a data network. land. In this case, satellites 12 may include a transponder from C-band to C-band, or for example, a C-band transponder (uplink) to S-band (downlink). For this latter case, one or more L-band and S-band traffic channels can be assigned to send the DN 39, and then the gates 18 have suitable L-band and S-band transmitter and receiver circuits, as well as antenna (s) , respectively, such as GOCC 38 and SOCC 36. In Figure 4A, all satellites 12 may not be geosynchronous orbiting satellites, although in Figure 4B at least one of satellites 12 'may be an orbiting satellite geosynchronous It should be noted that all DN 39 can be instrumented using wireless RF links or only a part of them; It should also be noted that wireless RF links can be used in conjunction with terrestrial data links to offer fault tolerance and redundancy. Alternatively, certain types of messages and / or status information may be sent through the terrestrial data network, while other types of messages and / or status information may be sent through the wireless RF data network. In addition, all or a portion of the wireless RF links can employ, for example, repeaters and ground-based microwave links, and do not need to be routed specifically through satellites. Also, within the scope of this invention are used one or more satellites that are not from the constellation of communication satellites 12 for sending the DN 39; for example, and as shown in Figure 4B, one or more Medium Terrestrial Orbiting and / or geosynchronous satellites can be used to provide complete terrestrial coverage for DN 39. In general, each satellite 12 of the LEO constellation operates to retransmit the satellite. information from gates 18 to users (band advance link C 19a with band advance link S 17a), and to relay information from users to gates 18 (band return link L 17b with return link from band C 19b). This information includes SS-CDMA synchronization, location and access channels, as well as power control signals. Also, various CDMA pilot channels may be used, as described in more detail below. The satellite ephemeris update data also communicates with each of the user terminals 13 from the gate 18 via the satellites 12. The satellites 12 also retransmit communication signals between the users and the gates 18, and can provide security to reduce unauthorized use. If used, each pilot channel that is transmitted by the gate 18 can be transmitted at the same power level, a higher power level or a lower power level than the other signals. There is a pilot channel in each FDMA channel in each ray. All pilots are derived from a synchronized common PN seed code for the GPS System Time. Each gate 18 applies a time offset to create a PN code with a different phase shift. The time offset is used by the user terminal 13 to determine which gate the pilot is transmitting. The pilot enables a user terminal 13 to acquire the time handling of the forward CDMA channel; provides a phase reference for coherent demodulation; and provides a mechanism for performing signal strength comparisons to determine when to initiate the transfer; however, the use of the pilot channel is not mandatory and other techniques can be used for this pse. In operation, satellites 12 transmit telemetry data from the spacecraft that include measurements of the operational state of the satellite. The telemetry beam of the satellites, the commands of the SOCC 36 and the communication feeder links 19 share the C-band antennas 12g and 12h. For those gates 18 that include a TCU 18a, the telemetry data received from the satellite can be immediately transferred to the SOCC 36; or the telemetric data can be stored and later transferred to SOCC 36 at a later time, almost always at the request of the SOCC. The telemetry data, transferred immediately or stored and transferred later, can be sent by DN 39 as package messages; each message in packet contains a single frame of minor telemetry. If more than one SOCC 36 provides satellite support, the telemetry data is routed to all SOCCs. The SOCC 36 has several interface functions with the GOCC 38. An interface function is the orbit position information in which the SOCC 36 provides orbital information to the GOCC 38, therefore each gate 18 can accurately track four satellites that can be in view of the gate. This data includes data frames that are sufficient to allow the gates 18 to develop their own satellite contact lists using known algorithms. It is not necessary for SOCC 36 to know the scheduling programming of the gates. The TCU 18a searches for the downlink telemetry band and uniquely identifies the satellite that is being tracked by each antenna, before the propagation of the commands. Another interface function is the satellite status information that is reported from SOCC 36 to GOOC 38. Satellite status information includes satellite / transponder availability, battery status and orbital information, and incorporates, in general, any limitations related to the satellite that would prevent the use of part or all of the satellite 12 for communication pses. An important aspect of the system 10 is the use of SS-CDMA together with the diversity that is combined in the receivers of the gate and in the receivers of the user terminal. The diversity combination is used to decrease the fading effects when the signals arrive at the user terminals 13 or the gate 18 from the multiple satellites through multiple or different path lengths. The tilt receivers in the user terminals 13 and the gates 18 are used to receive and combine the signals from multiple sources; as an example, a user terminal 13 or gate 18 provides the diversity combination for the forward link signals or the return link signals that are being received at the same time and transmitted through multiple rays of the satellites 12. In this regard, the description of the US Patent Do not. ,233,626, issued on August 3, 1993 to Stephen A. Ames entitled "Extended Spectrum Communication System of Repeater Diversity", is hereby incorporated by reference in its entirety. The performance in the reception mode of the continuous diversity is higher than that of receiving a signal through a satellite repeater, and also there is no break in the communication if a link is lost due to the reflection or blocking of trees or other obstructions that have an adverse impact on the received signal.

The directional and multiple antennas 40 of one of the gates 18 have the ability to transmit the signal of the forward link (gate to user terminal) through different rays of one or more satellites 12 to support the diversity combination in the user terminals 13. The omnidirectional antennas 13a of the user terminals 13 transmit through all the satellite beams that can be "seen" from the user terminal 13. Each gate 18 supports a control function of Transmitter power to direct slow fades, and also supports block interconnection to direct media flushes to fast. The control of the power is carried out in the forward and return links. The response time of the power control function is adjusted to suit, in the worst case, a round trip delay of 30 msec satellite. A synchronization channel (SYNC) generates a beam of data that includes the following information: (a) time of day; (b) identification of the transmission gate; (c) satellite calendar; and (d) assigned location channel. The location channel sends various types of messages that include: (a) a system parameter message; (b) a message of the access parameter; and (c) a message from the CDMA channel list. The parameter message of the system includes the configuration of the location channel, registration parameters and parameters that support the acquisition. The access parameter message includes the configuration of the access channel and the data rate of the access channel. The message from the CDMA channel list sends, if used, a related pilot identification and the Walsh code assignment. The location channel also sends a list of the adjacent gates and their pilot signals, as will be described in more detail below. The access channel is employed by the user terminal 13 to communicate with the gate 18 when the user terminal 13 is not using the traffic channel. The access channel is used for exchanges of short signaling messages, such as call orientation, answering to pagers and registration. From the access channel, the gate 18 receives and decodes a burst from a user terminal 13 requesting access. The message of the access channel is comprised in a long preamble after a relatively small amount of data. The preamble is the long PN code of the user terminal. Each user terminal 13 has a unique long PN code generated by a shift in the polynomial of the common PN generator. After receiving the access request, the gate 18 sends a message on the forward link location channel recognizing the reception of the access request and assigning a Walsh code and a frequency channel for the user terminal 13 to establish a traffic channel. User terminal 13 and gate 18 switch to the assigned channel element and initiate duplex communication using the assigned Walsh code (s) (expansion). The return traffic channel is generated in the user terminal 13 by digitally encoding the digital data from the local data source or the vocoder of the user terminal. Then, the data is interconnected en bloc at predetermined intervals and applied to a 64-Ary modulator and a data burst scrambler to reduce the correlation, and therefore the interference between the return traffic channels. Then, the data is added to the zero offset PN code and transmitted through one or more of the satellites 12 to the gate 18. Gate 18 processes the return link by using, for example, a fast Hadamard transformer (FHT) to demodulate the Walsh 64-Ary code and provide the demodulated information to the diversity combiner. The foregoing was a description of the preferred embodiment of the present invention of the communication system 10. The preferred embodiments of this invention are described below. In a presently preferred embodiment, the user terminals 13 have the ability to register and receive service only from the satellite system (a single mode), or from the satellite system or a terrestrial system (multiple mode). In the latter case, preference may be given to one system over another during a first registration attempt. In case of failure to obtain the service of the preferred system, it can be attempted automatically with the other system. In this regard, reference can be made to the U.S. Patent Application. commonly assigned S.N. 08 / 707,534, filed on 4/9/96, entitled "Method and mobile land mobile terminal / satellite system", by R.A. Wiedeman and M.J. Sites, incorporated here entirely by reference. As indicated previously, the pilot signal is an unmodulated direct-sequence spread spectrum signal. The pilot signal allows the user terminal 13 to achieve the time handling of the forward CDMA channel, by which a phase reference for coherent demodulation is provided, while also providing a means for the comparison of signal strength to determine when a transfer begins. Multiple pilot signals are transmitted through each gate 18, one on each FDMA channel. Figure 5 illustrates three exemplary service areas (SA), marked as A, B and C. Service area A includes a gate A 18 that serves SA A and SA C, although a B 18 gate serves SA B Also, three rays related to satellites A, B and C are illustrated, in particular external rays 15 and 12 of satellites A and B, respectively, and an internal beam 1 of satellite C. A gate D 18 is located outside of the service areas SA-A, SA-B and SA-C, but within the ray 1 of satellite C. A user terminal 13 is located within SA-A and is within all of the luminous point rays 15, 12 and 1 of satellites A, B and C, respectively.

It is assumed that the user terminal 13 attempts to access the system 10 from a condition without power in the beginning. With respect to the logic flow diagram of Figures 6A and 6B, the following steps are executed by the user terminal 13 in cooperation with the gate controller 56 of Figure 2. In block A, the user terminal (UT) 13 lights up (a cold start condition). The UT 13 has access to an indication stored in advance of a gate number, such as the newly used gate and the primary FDMA channel number for the gate. In many cases this gate will be the starting gate of the UT. In block B, UT 13 tunes the channel and attempts to acquire the pilot signal for the primary FDMA channel. For example, the pilot signal may be the carrier signal employed by UT 13 to obtain the initial system synchronization and provide time, frequency and phase tracking. The different pilot signals can be transmitted with the same code, but with different code shifts, in order to distinguish them. If the UT 13 manages to acquire the primary FDMA channel, the control passes to the L block, as described below. If the UT 13 fails to acquire the primary FDMA channel (and the gate), control passes to block C, in which UT 13 has access to a stored list of channels and tunings for a predetermined channel (e.g., channel 7). of 13 channels) that is specified as a primary channel.

For example, if the test in block B fails, the UT 13 may have been carried throughout the country or to another country, since the time had just been used. In this case, the UT 13 may not find its starting gate 18 when it attempts to access the system 10. In block D, the UT 13 attempts to acquire the pilot signal in the channel from the predetermined channel list. If UT 13 fails, control passes to block D1 to select another channel from the list, and then return to block C. If the channel list has been exhausted without access to a gate, control goes to block D2, in which the initial procedure for acquiring the system is concluded. Assuming that UT 13 achieves acquiring a pilot signal in a channel from the predetermined channel list in block D, UT 13 synchronizes to the pilot signal, then instead, accesses the sync channel to gain access to a satellite database and other information. This database facilitates the rapid acquisition of the pilot signal for future calls. The UT 13 then has access to the location channel (block E). The operation that acquires these channels can be designated collectively as a receiver of a reference signal. From the localization channel, the UT 13 can obtain the list of gates and the displacements of the respective pilot signal (block F). In block G, UT 13 determines if the starting gate of the UT is in the list of gates. If the gateway of the UT is in the list of gates, the UT 13 goes to the channel specified for the departure gate and acquires the pilot signal in that channel, and the control goes to block L, as will be described later , so that UT 13 can have access to the starting gate. If the starting gate of the UT is not in the list of gates, control passes to blocks H, I and li, where a gate is selected (if one is available in the gate list) and an attempt is made to Acquire the selected gate. If there are no more gates in the block H list, the control returns to block C. Again, with respect to FIG. 5, the selected gate 18 may not service the area in which the user terminal is located. For example, UT 13 appears as if it were located in SA-A and should be assigned to gate A; however, UT 13 may be receiving the pilot signal in a particular channel of gate D through internal beam 1 of satellite C. Although UT 13 has also been receiving pilot signals from ports A and B, the gate D is selected by the higher signal strength of its pilot signal, or because the gate pilot signal is the first that the user terminal 13 could acquire, or the gate can be selected based on some other criteria. Assuming that this is the first transfer that passes through the acquisition procedure, the control passes through block J to block K to determine if the selected gate is also the initial gate that was acquired in blocks D and E. If it is thus, control passes to block M, where UT 13 sends an access request on the specified access channel. If the selected gate is not the gate selected in the beginning in block K, then the control goes to block L where the UT 13 acquires the location and synchronization channels of the selected gate, and therefore determines the parameters of the channel. access. Then, the control goes to block M to send an access request in the access channel to the selected gate. The access request can be, for example, a request to connect the UT 13 in the database of active users, or it can be a request to initiate a call, or they can be both. A call may be made to any of the terrestrial telecommunication systems that are connected to the gate 18, such as the PSTN or a private network, or to another user terminal 13 in the service area of the gate 18, or to any other device that UT 13 designates. In the block N, the selected gate, for example gate D of figure 5, receives the access request from the UT 13. In this embodiment of the invention, the selected gate 18 performs a position location in the UT 13 using any of the various position determination techniques, such as multilateral time measurements, receipt of GPS information from UT 13 or other means. In block P, the selected gate 18 makes a determination based, at least in part, on the location of position, whether it accepts or rejects the UT 13. Other acceptance / rejection criteria may also be used (for example, if it exists or not an itinerary agreement with the service provider of the user's departure gate). If the UT 13 is accepted, the control passes to the S block where the UT 13 is authenticated and, assuming that the UT 13 is authenticated, the UT 13 is added to the VLR 54c of the gate (Figure 2) as an active user in this gate. The control goes to block T where the gate warns UT 13 of the acceptance and, if a call request was sent, initiates call establishment. In block U, the gate determines whether UT 13 initiated a call request. If it is a No, the control goes to block V to enter a reserve status, waiting for a call request. In block W, the call request is received and, in block X, gate 18 allocates one or more traffic channels to the UT 13. The call starts and is in progress in block Y. In block Z , the call ends and the control returns to block V so that gate 18 waits for the next call request. If the determination in block U is a Yes, then control immediately passes to block X to assign one or more traffic channels to UT 13. Regarding figure 5 again, and assuming for this example that UT 13 sends a request for access to gate D, gate D determines from the determined location of the UT that is in SA-A, and that UT 13 must be assigned to gate A. If UT 13 was determined to be in SA-C, UT 13 would still be assigned to gate A, which is assumed, in this example, will also service the SA-C. If, instead, UT 13 were to be determined to be located in SA-B, then UT 13 would be assigned to gate B.

Assuming that gate D determines in block P that UT 13 will not be accepted, gate D (in block Q) informs UT 13 through the forward link, in the location channel, that UT 13 does not it is accepted The rejection message may also include an identification of a gate for which the TU 13 next time must request acceptance, as described above. Also, within the scope of this invention, gate D simply does not respond to the request for access by the UT 13 which, after a certain period, will be informed by means of failure that gate D did not accept the UT 13. After of a predetermined period, the UT 13 will try with another gate. As a result of not being accepted by gate D, UT 13 determines if the gate that indicated the rejection was the initial gate (that is, block B took the path of Yes). If it is a Yes, then the control goes to block C; if it is a No, the control goes to block R, where UT 13 removes the gate previously selected from the list of gates determined in block F, and the control returns to block H to select a next gate in the list. The next gate can be the gate that has, for example, the next strongest pilot signal. Alternatively, and if gate D included a gate identifier in the rejection message, UT 13 selects the gate designated in the rejection message. In block J, the control now passes to block L, and the access request is made to the next gate in block M, as described above.

Figure 7 shows a further embodiment of this invention, in which the blocks A-N are as in Figure 6A. After receiving the access request in block N, the gate makes sure that block S authenticates UT 13. In block U, UT 13 is rejected if it is not authenticated (block v). If UT 13 is authenticated in block U, then block O is executed to perform a position location in authenticated UT 13. Then processing continues in block P, as in FIG. 6B, to determine whether the UT access request is accepted or rejected. Reference is now made in FIG. 8 to show a block diagram of one of the user terminals 13. Coupled with the antenna 13A (which could consist of separate receiving and transmission antennas) is an RF section of the satellite having a receiver and a transmission that can be tuned to receive the downlink satellite transmissions 17B, on various FD channels selectively, and to perform the uplink 17A transmission, on various FD channels selectively. A modulator and demodulator (modem) 13C includes extended spectrum circuitry suitable for modulating and broadcasting the uplink transmissions and for demodulating and not extending the uplink transmissions. A controller 13D is responsible for the overall operation of the user terminal 13 and is connected to the modem 13C, a user interface 13E, an audio portion 13F and a memory 13G. The user interface 13E is coupled with a screen (not shown) and the user input device, usually a conventional keyboard (not shown). The audio portion 13F includes circuitry for directing a loudspeaker and for receiving and digitizing a signal input from a microphone (mic). The memory 13G stores the terminal identifier (ID) and the type (for example, fixed, hands, etc.), the last channel information that is used in block B of figure 6A, the list of gates that are they obtain in the block F of figure 6A, the satellite calendar data, the identifications of the assigned gates and frequency channels, the assigned code or dispersion codes, and any other data and programs necessary to operate the user terminal 13. Likewise, a port can be provided to be used in the transmission of data and reception requests, such as a port that can be connected to the data processor, a facsimile or some other device that resorts to and / or manages data. In accordance with one aspect of this invention, each of the gates 18 of the system 10 includes a capability to receive and accept an access request from a user terminal 13, and also to receive and reject an access request from a UT 13. In case of rejecting the access request of the UT 13, the gate 18 can also provide the indication of another gate or gates for the UT 13 to make a next access request. That is, each of the gates 18 has the ability to play an active role in the allocation of a TU 13, either for themselves or for another gate. Preferably, this functionality is implemented in software executed by the gate controller 56 (FIG. 2), although the dedicated circuit can also provide the execution of this function, either in whole or in part. Although described above in the context of the illustrative embodiments of this invention, it should be noted that some modifications can be made to these embodiments, and that these modifications will fall within the scope of the teaching of this invention. For example, some of the blocks illustrated in Figures 6A, 6B and 7 may be executed in a different order than shown, however, the same result is obtained. In addition, for example, it should be noted that the gate 18 may use some different criteria when making a decision regarding the acceptance or rejection of an access request from a certain user terminal 13. For example, and in addition to considering the determined location of user terminal 13, gate 18 may also consider one or more of: (a) a current gate load or a predicted load of gate 18 (as obtained from GOCC 38 by DN 39); (b) any deterioration in the system, such as in one or more rays of the satellites 12 that are in view of the user terminal 13 that is requesting access (which may also be received from the GOCC 38 or the SOCC 36 by the DN 39); (c) the type of user terminal 13 that is requesting access (i.e., user terminal 13 may also transmit its type, eg, fixed, hands, etc., when transmitting the access request); (d) the existence of a shared gate that shares a plurality of service areas; and (e) other criteria, such as the presence of an itinerant agreement. Another criterion on which the acceptance or non-acceptance of the UT 13 is based is a telephone number sent by the UT 13 with a call setup service request that includes authentication data. For example, and referring again to Figure 5, if the gate A can determine, from the number, that the UT 13 that is making a call is a private network that is known from the information of a base of data that will connect to gate B (but not gate A), then gate A can reject the call request, and provide to UT 13 a list of gateways that includes only gate B. Similarly, if the UT 13 is determined to call another UT that is known to be in the service area of gate B, then gate A can reject the call request, and provide UT 13 with a list of gateways that includes gate B As such, a method is provided for operating a telecommunication system having at least one Earth orbit satellite to send signals between a user terminal and one of several gates. The method that includes the steps of (a) receiving a service request that is transmitted from a user terminal, the service request that is received at a first gate and indicates a destination telephone number to which a call will be placed; (b) determine if the first gate has the ability to service the destination telephone number; and, if not, (c) transmitting a message to the user terminal, the message that rejects the service request and includes an indication of another gateway that has the ability to service the destination telephone number. For example, the destination telephone number may correspond to a telephone number of a private network or may correspond to a telephone number of another user terminal. Another criterion that is based on the called number is a determination by the gate so that the gate can complete the call in an economical manner. For example, assuming that UT 13 is in a gate overlapped service area and calls a number in country B, but first has access to a gate in country A. The gate in country A examines the called number and determines that the user's call will be more economical if it is handled through the gate of country B. In this case the gate in country A sends a rejection message to UT 13, with an indication to contact the gate in country B. As such, a method is provided for operating a telecommunication system having at least one Earth orbit satellite for sending signals between a user terminal and one of several gates. The method that includes the steps of (a) receiving a service request that is transmitted from a user terminal, the service request that is received at a first gate and indicates a destination telephone number to which a call will be placed; (b) determining if the first gate can connect the call to the destination telephone number with less expense as opposed to another gate that can connect the call to the destination telephone number; and, if not, (c) transmitting a message to the user terminal from the first gate, the message rejecting the service request includes an indication of at least one other gate that is determined to possess the ability to connect the call with Less expense than the first gate. Although it is described in the context of an extended spectrum CDMA system using LEO curved tube satellites, the teachings of this invention are also applicable to other types of modulation and access schemes, such as multiple access / time division (TDMA) systems, with satellites that perform resident signal processing of communication traffic (e.g., regenerative repeaters). ), and with satellites in other orbital configurations, such as polar-orbiting LEO satellites, LEO satellites in elliptical orbit, satellites in mid-earth orbit configurations, and geosynchronous satellites. Furthermore, in some embodiments of this invention some or all of the user's connection and / or acceptance functions may be performed on board a satellite, either alone or in conjunction with one of the gates 18. If the satellites are equipped with inter-satellite links (such as optical links or RF), then the information can be passed between the satellites, and the connection and / or user acceptance functions as described above can be performed by two or more satellites together, either isolated or in combination with the Therefore, although the invention has been illustrated and described in particular with respect to the preferred embodiments thereof, it will be assumed, for those skilled in the art, that changes in shape and details can be made therein without departing from the scope and spirit of the invention.

Claims (37)

NOVELTY OF THE INVENTION CLAIMS

1. - A satellite communication system, characterized in that it comprises at least one satellite; a plurality of gates; and at least one user terminal comprising means for bi-directionally communicating at least one of the gates through at least one satellite; wherein each of the various gates comprises the means for receiving an access request from at least one user terminal through at least one satellite, and further comprises means for notifying the requesting user terminal that the terminal user is one of those accepted by the gate to establish a communication link or is not accepted by the gate to establish the communication link.

2. A satellite communication system according to claim 1, further characterized in that the plurality of gates is bi-directionally coupled with a data network, and wherein the data network comprises at least one terrestrial segment and one space segment.

3. A satellite communication system according to claim 1, further characterized in that each of the gates comprises a means for determining a location of a user terminal, and wherein the means of notification responds at least in part to the determined location to determine the acceptance of the user terminal.

4. A satellite communication system according to claim 1, further characterized in that at least one user terminal consists of a means for storing a list identifying each of the gates, and wherein the user terminal further comprises means for selecting a gate from the list to which an access request is sent.

5. A satellite communication system according to claim 4, further characterized in that the user terminal receives the list through at least one satellite from one of the gates.

6. A satellite communication system according to claim 1, further characterized in that at least one user terminal consists of a means for initially tuning to a frequency channel that the user terminal has just used and, if the newly used frequency channel is not available, to tune to one or more predetermined channels.

7. A satellite communication system, comprising: at least one user terminal consisting of a first transceiver for transmitting signals, including a request for service signal, to a first RF link and to receive signals from the first link RF; at least one satellite comprising the means for receiving signals and transmitting signals to the first RF link and for transmitting signals and receiving signals from a second RF link; and at least one gate having at least one service area related thereto and comprising a second transceiver for transmitting signals and receiving signals from the second RF link, the second transceiver which is bidirectionally coupled with at least one network terrestrial communication for transmitting a communication signal at least for a user terminal at least from a communication network with the second RF link and for transmitting a communication signal to at least one user terminal from the second RF link at least with a communication network, at least one gateway further comprising the decision means having an input to receive, from the second RF link, a service signal request from at least one user terminal, the decision means operating to determine the acceptance or rejection of the service request, in accordance with at least one criterion.

8. A system according to claim 7, further characterized in that at least one gate comprises a means for determining a location of at least one user terminal, and where the means of determination responds to the means of location determination to determine if at least one criterion is satisfied.

9. A system according to claim 7, further characterized in that the user terminal includes the means for receiving, from the first RF link, at least one reference signal that is transmitted at least by a gate, and wherein the terminal The user directs the service request to a selected gate based at least in part on a received reference signal.

10. A system according to claim 9, further characterized in that at least one user terminal directs a service request to a gate selected in accordance with a received reference signal having a high received signal strength.

11. A system according to claim 7, further characterized in that there are a plurality of gates, each of which has a gate identifier, each of those gates further comprises means for transmitting a list comprising at least some other gate identifier with the second RF link, and wherein at least one user terminal further comprises the means for storing the list that is received from the first RF link.

12. A system according to claim 11, further characterized in that at least one user terminal directs a service request to a gateway having a gateway identifier in the stored list.

13. A system according to claim 8, further characterized in that there are a plurality of gates, each of which has a gate identifier, each of those gates further comprises the means for transmitting at least one gate identifier. with the second RF link for the reception at least by a user terminal by not accepting the service request from at least one user terminal, at least one transmitted gate identifier that is selected at least partly in compliance with the location determined to indicate, to the user's terminal, a gate that has a service area in which the user terminal is determined to locate it.

14. A method for operating a telecommunication system having at least one Earth orbit satellite to send signals between a user terminal and one of the gates, at least one of the gates that is coupled with a terrestrial telecommunication system, which comprises the steps of: in the user terminal, trying to receive a signal from a newly used gate; if successful, transmit a request for access to the newly used gate; if this is not achieved, try to receive a predetermined communication channel; if it is achieved, obtain a list of gates from a gateway transmitting the predetermined communication channel and store the list of gates in the user terminal; determine if a predetermined gate is included in the list of gateways and, if so, transmit a request for access from the user terminal to the predetermined gate; and if the default gate is determined not to be included in the list, select one of the gates from the list and transmit the access request to the selected gate.

15. A method according to claim 14, further characterized in that it comprises the steps of: receiving the access request in the gate and determining a location of the user terminal; determine, based at least in part on the given location; if it accepts the user terminal to establish a communication with a terrestrial telecommunication system or another user terminal; and, if the user terminal is accepted, authenticate the user terminal and assign at least one satellite traffic channel for the authenticated user terminal.

16. A method according to claim 15, further characterized in that it comprises the steps of: notifying the user terminal of the rejection, if the gate determines to reject the user terminal; in the user terminal, remove the gate from the gate list and select another gate from the list to make the next access request.

17. A method according to claim 14, further characterized in that the step of selecting a gate includes an initial step of acquiring a reference signal from at least a few gates in the list and selecting one of the gates according to less with a characteristic of the acquired reference signals.

18. A method according to claim 14, further characterized in that it comprises the steps of: in the gate, receiving the access request; perform authentication of the requesting user terminal; if the user terminal does not authenticate, reject the access request; if the user terminal is authenticated, determine a location of the user terminal; determining, based at least in part at the determined location, accepting the user terminal to establish a communication with a land telecommunication system or other user terminal; and, if the user terminal is accepted, assign at least one satellite traffic channel for the authenticated user terminal.

19. A method according to claim 18, further characterized in that it comprises the steps of: notifying the user terminal of the rejection, if the gate determines to reject the user terminal; in the user terminal, remove the gate from the gate list and select another gate from the list to make the next access request.

20. A method for operating a telecommunication system having at least one Earth orbit satellite for sending signals between a user terminal and one of the gates, at least one of the gates that is coupled with at least one telecommunication system terrestrial, which comprises the steps of: receiving, in a gate, a service request from the user terminal, the service request that passes through at least one satellite; and, based on at least one criterion, notify the requesting user terminal that the user terminal is one of those accepted by the gate to establish a communication link, or not accepted by the gateway to establish the communication link.

21. A method according to claim 20, further characterized in that the notification step includes a step of allocating at least one satellite traffic channel for an accepted user terminal.

22. A method according to claim 20, further characterized in that the notification step includes a step of transmitting an identification to at least one other gate for an unaccepted user terminal, and further comprising the step of performing the next service request for the identified gate.

23. A method according to claim 20, further characterized in that it comprises the initial steps of: in the user terminal, acquire a reference signal from a first gate; receive a list identifying at least one other gate of the first gate; receive a reference signal from at least one other gate in the list; and, selecting a gate that has a reference signal with a higher received signal strength.

24. A method according to claim 20, further characterized in that at least one criterion includes a location of the user terminal at least, a current communication traffic load of the gate, a predicted communication traffic load of the gate, the presence or absence of any RF deterioration, a type of user terminal, a lower cost routing for a call, a destination for a call, and the presence or absence of an itinerant agreement with the service provider the requesting user terminal.

25. - A method according to claim 20, further characterized in that it comprises the initial steps of: at the user terminal, acquiring a reference signal from a gate; and, in accordance with the information obtained from the reference signal, transmit a service request for the gate.

26.- A method according to claim 20, further characterized in that the step of notifying includes a step of not responding to the service request of an unaccepted user terminal, and further comprising the steps of: in the terminal of user, wait for a predetermined time to receive a response from the gate; and, at the end of the predetermined time, make the next service request for another gate.

27. A satellite communication system, further characterized in that it comprises: at least one satellite; a system controller; a plurality of gates; at least one user terminal comprising means for bi-directionally communicating at least one of the gates through at least one satellite; and, a data network that connects the system controller and the plurality of gates by which the system controller selectively allocates the system resources for each of the gates, based at least in part on a predicted request. for system resources, the data network that is being sent over a wireless network and a combination of a wired network and a wireless network.

28. - A satellite communication system according to claim 27, further characterized in that each of the gates are coupled bidirectionally at least with a terrestrial communication system, and wherein each of the gates comprises the means for receiving a requesting access to at least one user terminal through at least one satellite, and further comprising the means for notifying the requesting user terminal that the user terminal is one of those accepted by the gateway to establish a communication link with a terrestrial communication network or another user terminal, or is not accepted by the gateway to establish the communication link.

29. A satellite communication system according to claim 27, further characterized in that each of the gates are bidirectionally coupled with a database of the active user terminals with which connection was made, and where each of the gates comprises the means for receiving a connection request from at least one user terminal through at least one satellite, and further comprises means for notifying the requesting user terminal of one of the following: (a) that the connection request of the user terminal was accepted by the gate to be stored in the database; and (b) that the connection request of the user terminal was not accepted by the gate.

30. - A satellite communication system according to claim 27, further characterized in that the wireless network consists of RF links at least between a satellite and at least one of the gates.

31.- A satellite communication system according to claim 27, further characterized in that the wireless network consists of terrestrial RF links at least between two of the gates.

32. A satellite communication system according to claim 27, further characterized in that the data network transmits information to coordinate the assignment of user terminals for each of the gates. 33.- A method for operating a telecommunication system having at least one Earth-orbiting satellite to send signals between a user terminal and one of the gates, at least one of the gates that is coupled with at least one telecommunication system terrestrial, which comprises the steps of: receiving a service request that is transmitted from a user terminal; and, based on at least one criterion, which determines whether the requesting user terminal is accepted for the service and notifies the requesting user terminal that the user terminal is one of those accepted for the service, or not accepted for the service. service, wherein at least one criterion includes at least one location of the user terminal, a current communication load of the system, a predicted communication traffic load of the system, the presence or absence of any deterioration of the system, a type of user terminal and the presence or absence of an itinerant agreement with the service provider of the requesting user terminal, and wherein the steps of deciding and notifying are executed by at least one of the gates, one satellite at least , or by a combination of at least one gate and one satellite at least. £ 5 34.- A method for operating a telecommunication system that has at least one Earth orbit satellite to send signals between a user terminal and one of the gates, comprising the steps of: receiving a service request that is transmits from a user terminal, the service request that is received in a first gate and that 10 indicates a destination telephone number where a call will be placed; determine if the first gate has the ability to service the destination telephone number; and if not, transmit a message to the user terminal, the message rejects the service request and includes an indication of another gate that has the ability to service the 15 destination telephone number. 35.- A method according to claim 34, further characterized in that the destination telephone number corresponds to a telephone number of a private network. 36.- A method according to claim 34, 20 further characterized in that the destination telephone number corresponds to a telephone number of another user terminal. 37.- A method for operating a telecommunication system that has at least one satellite of Earth orbit to send signals between a user terminal and one of the gates, comprising the steps of: receiving a service request that is transmitted from a user terminal, the service request that is received in a first gate and that indicates a destination telephone number in which a call will be placed; determine if the first gate can connect the call to the destination telephone number at a lower cost than another gate can connect the call to the destination telephone number; and, if not, transmit a message to the user terminal from the first gate, the message rejects the service request and includes an indication of at least one other gate that is determined to be able to connect the call with less cost than the first gate. . SUMMARY OF THE INVENTION A satellite communication system includes at least one satellite, a system controller, a plurality of gates, and at least one user terminal operable to bi-directionally communicate at least one of the gates through at least one satellite; each of the various gates is bi-directionally coupled with at least one terrestrial communication system and acts to couple the user terminal with the terrestrial communication system through at least one satellite; in accordance with an aspect of this invention, each of the various gates is operable to receive a request for access from the user terminal through at least one satellite, and in addition they are operable to notify the requesting user terminal, to through at least one satellite, that the user terminal is one of those accepted by the gate to establish a communication link and not accepted by the gate to establish the communication link; a gateway that does not accept a user terminal can indicate to the user terminal, based at least in part at a certain location of the user terminal, an identification of a gate for which the user terminal must request access or intentions of connection; In addition, the system includes a network of data interconnecting the system controller and the plurality of gates; The data network can be sent and included in a wired network, a wireless network and a combination of a wired network and a wireless network. í IM / ag * mvh * jtc P99 / 1175F