MXPA97009493A - System of management of satellite energy diversity resources - Google Patents
System of management of satellite energy diversity resourcesInfo
- Publication number
- MXPA97009493A MXPA97009493A MXPA/A/1997/009493A MX9709493A MXPA97009493A MX PA97009493 A MXPA97009493 A MX PA97009493A MX 9709493 A MX9709493 A MX 9709493A MX PA97009493 A MXPA97009493 A MX PA97009493A
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- Mexico
- Prior art keywords
- communication
- communication signal
- user terminal
- receiver
- satellite
- Prior art date
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Abstract
Methods and apparatus are described for improving and optimizing trajectory diversity delivery in a satellite repeater-based communication system, thereby conserving both the FDM channels and the utilization of the satellite power. The reception of communications is improved when one or more of the transmitters of the satellite repeater is blocked or severely weakened, recognizing the need for satellite path diversity on a real time or near real time basis. A user terminal is thus enabled to receive sufficient signal strength to prevent an incoming call from being terminated automatically. The system raises the diversity of the satellite path applied to: (a) the classes (types) of user terminals and / or (b) to the individual user terminals, as a function of the location and also of an environment of local RF propagation, user terminal. Additionally, the invention teaches a consideration of the satellite resources that are available at any given time point, and may restrict or limit the availability of satellite path diversity, thereby increasing the capacity of the control system that goes into increase
Description
SYSTEM OF MANAGEMENT OF DIVERSITY RESOURCES IN SATELLITE REPEATER
FIELD OF THE INVENTION
This invention relates in general to satellite communication systems and, in particular, to satellite communication systems in which the satellites are used as repeaters of the communication signal.
BACKGROUND OF THE INVENTION
The blocking and weakening of the signal in mobile communication systems are well known. Generally, systems based on satellite have more demanding requirements than terrestrial based systems, due to the significantly longer propagation trajectories. In mobile satellite communication systems, the blocking and weakening of user terminals by buildings, trees and terrain can be mitigated by using multiple satellite repeater transmitters in orbit to send multiple copies of a signal, through some or all satellite repeater transmitters in view to a user who is experiencing potentially blocking and weakening of signal. These mitigation techniques, especially those using spread spectrum systems, utilize multiple signal path diversity (hereinafter referred to simply as "path diversity") as a means to maintain communication paths when individual mobile users are in situations blocking and weakening. The satellite communication systems of terrestrial orbit (LEO) in particular can exploit the diversity of trajectories, since there are multiple satellites and, therefore, multiple and different trajectories of communication to and from the user. The well-known or proposed systems of this type, in addition to using multiple access with division of code (CDrlfl, acronyms for its designation in English Code Multiple Division necees) are usually channeled by multiple frequency division plexer (FDH, acronyms for its designation in English: Frequeney Division iultiplex). Traditionally, providing path diversity has an adverse effect of requiring the system to use many satellites. This increases the total power demand for each satellite and also requires each satellite to make available the same RF channels for each user for the path diversity transmissions. The final result may be a reduction in the total capacity of the systems due to deficiencies in the allocation of the RF channel. One approach to providing diversity of trajectory is to provide indiscriminately for all users the diversity of trajectory. However, in fact, the inventor of the present has realized that there are many different types of user terminals, as well as many different types of communication environments in which a given user can reside, temporarily or permanently. For example, certain users will use vehicle-mounted terminals, which can move through the environment rather quickly. Other users may use portable or fixed hand terminals, which may not be moving absolutely. Additionally, there is a variety of terrains on which users may be located, such as oceans, deserts, jungles, suburban, urban, rural farm, etc. It can be appreciated that not all communication environments require the same level of path diversity and, additionally, that not all user terminals within a given environment require the same level of path diversity.
BRIEF DESCRIPTION OF THE INVENTION
The above problems and other problems are solved by a satellite communication system that is constructed and operated in accordance with this invention. Methods and apparatus are described to improve and elevate to the optimum point the supply of the diversity of trajectories in a communications system based on satellite repeater, thus conserving the FDM channels and the use of satellite power. The reception of multiple signals is improved, when one or more transmitters of satellite repeater (12) in orbit is blocked or severely weakened, recognizing the need for the diversity of satellite paths on a real time or near real time basis , therefore, a user terminal (13) is allowed to receive sufficient signal power to prevent a communication that is proceeding automatically from optimizing the path diversity (consisting of multiple wireless links) that is applied a (a) the classes (types) of user terminals and / or (b) to individual user terminals as a function of the location and also of a local RF propagation environment of the user terminal, typically, the invention teaches a consideration of the satellite resources that are available at any given point in time, and may restrict or limit the availability of the diversified ad of the satellite path, thus increasing the total capacity of the system. Also, a particular user may find that he has a historical record or "signature" of operation within a certain environment. The historical record can be used to elevate the typical use of the user to the optimum point, thereby further refining the potential for greater operating efficiency of the system. This invention teaches a method for operating a satellite communication system that includes the steps of (a) initiating a communication between a user terminal and a ground station, through at least one repeater of satellite communication signal; (b) classifying the user terminal as to type and / or determining a location of the user terminal within a service coverage area of the ground station; and (c) selecting a number of satellite communication signal repeaters to relieve communication between the user terminal and the ground station; the selected number being a function of at least the type and / or location of the user terminal and other features that can be stored within a database. The selecting step may include a step of determining an RF energy propagation characteristic that is associated with the determined location of the user's terminal. The use of an RF propagation map of the service area is described for that purpose, deriving the map, for example, from the satellite images of the natural and artificial aspects within the service area. The selecting step can also include a step of considering a power control history in the user terminal. This is useful to distinguish, for example, a user terminal of mobile type that is in motion, from a mobile type user terminal that is found to be stationary. The selecting step may also include a step of considering a current availability of RF channels of the satellite communication signal, within satellite repeaters and the physical circuit load of the RF channels and satellite repeaters. In a currently preferred embodiment of this invention, communication is relieved as a communication signal with multiple code division access, of spectrum that is disseminated, between the user terminal and the ground station. In that case, the method includes the additional steps of: (d) receiving communication with the user terminal, where communication is received through different communication paths, associated with the individual repeaters of the selected number of signal repeaters of satellite communication; (e) equalizing at least the phase shifts and the time delays of the communication received from each of the different trajectories to provide a plurality of equalized communication signals; and (f) combining the equalized communication signals in a received, mixed communication signal.
BRIEF DESCRIPTION OF THE DRAWINGS
The aforementioned aspects and other aspects of the invention are more evident in the detailed description of the invention that follows, when read in conjunction with the attached drawings, in which: Figure 1 is a block diagram of a system of satellite communication that is constructed and operated in accordance with a currently preferred embodiment of this invention. Figure 2 is a block diagram of one of the gates of Figure 1; Figure 3ft is a block diagram of the communications instrumentation of one of the satellites of Figure 1. Figure 3B illustrates a portion of a ray pattern that is associated with one of the satellites of Figure 1. Figure 4 is a block diagram that illustrates the ground equipment support, the satellite's telemetry and control functions. Figure 5 is a block diagram of the DCMA subsystem of Figure 2. Figure 6 is a block diagram of a delivery link path diversity delivery system, in accordance with the present invention. Figure 7 is a block diagram of a portion of the path diversity supply system of Figure 6, in combination with a path diversity selection system in accordance with this invention. Figure 8 is a block diagram illustrating the reverse link from the user terminal to the gate. Figure 9 is a block diagram of a path diversity return link mode of this invention. Figure 10 illustrates an exemplary communications environment map, which is an aspect of this invention;
V Figure 11 is a flow chart illustrating a method 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 currently preferred embodiment of this invention. Before describing the invention in detail, a description of the communication system 10 will first be made, so that a more complete understanding of the present invention can be had. The communication system 10 can be conceptually subdivided into a plurality of segments 1, 2, 3 and 4. The segment 1 is here called a spatial segment; segment 2, a user segment; segment 3, a segment of land (land), and segment 4, a segment of the telephone system infrastructure. In the currently preferred embodiment of this invention there are a total of 48 satellites, for example, in a low Earth orbit (LEO) of 1414 km. The satellites 12 are distributed in eight orbital planes, with six satellites equispaced per plane (Ualker constellation). The orbital planes are inclined at 52 degrees with respect to the equator, and each satellite completes an orbit once every 114 minutes. This approach provides almost complete terrestrial coverage, and preferably at least two satellites are on the road at any given time from a particular user's use, between about 70 degrees south latitude and about 70 degrees north latitude. In such a manner, a user is able to communicate with or from any point on the surface of the earth within a gate 18 (GLJ) 18 or from other points on the surface of the earth (through the PSTN), through one or more gates 18 and one or more satellites 12, possibly also using a portion of telephone infrastructure segment 4. It should be noted at this point that the foregoing and following description of the system 10 represents only a suitable modality of a communication system within which the teaching of this invention may have use. That is, the specific details of the communication system should not be read or considered in a limiting sense when this invention is put into practice.
Continuing now with a description of the system 10, a smooth transfer (delivery) process between the satellites 12, and also between the individual beams of 16 point beams transmitted by each satellite (Figure 3B) provides uninterrupted communications with a multiple access technique with division of code (DCMA, acronym for its designation in English: Code Division Multiple Recess) of spectrum amplitude (SS = Spread Spectrum). The currently preferred SS-CDMR technique is similar to the transient standard TIñ / EIfl "Compatibility standard from mobile station to base station, for dual-band wide-band amplitude spectrum cellular system" TIft / EIA / IS-95 , July 1993, although other techniques and other amplitude and CDMA spectrum protocols can be used. Low terrestrial orbits allow fixed or mobile, low power user terminals 13 to communicate via satellites 12, each of which functions, in a preferred embodiment of this invention, solely as a "bent tube" repeater "to receive a communications traffic signal (such as voice and / or data) from a user terminal 13 or a gate 18, converts the received communication traffic signal to another frequency band and then retransmits the converted signal. That is, no signal processing occurs on board a received communications traffic signal, and satellite 12 is not aware of any intelligence that may be carrying a received or transmitted communication traffic signal. There is usually no need for one or more direct communication 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 terrestrial segment 3. , and transmits a signal only to a receiver located in user segment 2 or to a receiver located in ground segment 3. User segment 2 may include a plurality of user terminal types 13, which are adapted for communication with the satellites 12. The user terminals 13 include, for example, a plurality of different types of fixed and mobile user terminals, including but not limited to: mobile radiotelephones 14, laptops, mobile radiotelephones 15, vehicle mounted, from shipments 16 of the type of location / delivery of messages and fixed radiotelephones 14a. The user terminals 13 are preferably provided with ornnidirectional antennas 13a for bidirectional communication through one or more of the satellites. It should be noted that the fixed radiotelephones 14a can employ a directional antenna. This is advantageous in that it allows a reduction in the interference, with a consequent increase in the number of users that can be served simultaneously with one or more of the satellites 12. It should also be noted that the user terminals 13 can be from shipments of dual use, which include circuits to communicate - also in a conventional way with a terrestrial cellular system. With reference also to Figure 3R, user terminals 13 may be able to operate in a full duplex mode and communicate, for example, by means of RF links in L-band (lift link or return link 17b) and RF links in S band (downlink or send link 17a), through satellite transponders of sends 12a and 12b, respectively. The RF links 17b in the return L band can operate within a frequency range of 1.61 GHz to 1625 GHz, a bandwidth of 16.5 MHz < and are digital signals in voice packets and / or data signals, according to the preferred amplitude spectrum technique. The S-band RF links of consignments can operate within a frequency range of 2.485 GHz to 2.5 GHz, a bandwidth of 16.5 MHz. The RF links of shipments 17a are also modulated in gate gate 18, with digital signals in packet of voices and / or data signals, according to the amplitude spectrum technique. The 16.5 MHz bandwidth of the send link is divided into 13 channels with up to, for example, 128 users assigned per channel. The return link can have different bandwidths and a given user terminal 13 may or may not have a different channel assigned to it than the channel assigned in the send link. However, when operating in the diversity reception mode in the return link (which receives two or more satellites 12), the user is assigned the same send and return link RF channel, for each of them. the satellites The ground segment 3 includes at least one, but usually a plurality of gates 18, which communicate with the satellites 12 by means, for example, of a complete, full-duplex, C-band RF link 19 (link sending 19a (to the satellite), return link 19b (from the satellite)) operating within a frequency range generally above 3 GHz and, preferably, in the C band. The C-band RF links carry bidirectionally the communication feeder links and also carry satellite commands to the satellites and telemetry information from the satellites. The feeder link 19a may operate in the 5 GHz to 5.25 GHz band, while the return feeder link 19b may operate in the band from 6,875 GHz to 7,075 GHz. The I2g and 12h link antennas of the satellite feeder preferably they are wide-coverage antennas, which subtend a maximum terrestrial coverage area, as seen from the LEO satellite 12. In the currently preferred mode for the communication system 10, the angle subtended from a given LEO satellite 12 (assuming angles of elevation of 10 ° from the surface of the earth) is approximately 110 °. This produces a coverage area that is around 5,760 km in diameter. The L-band and S-band antennas are multi-beam antennas that provide coverage within an associated terrestrial service region. The L-band and S-band antennas 12d and 12c, respectively, are preferably congruent to each other, as illustrated in Figure 3B. That is, the transmission and reception beams from the spacecraft cover the same area on the surface of the earth, although this aspect is not critical for the operation of the system 10. As an example, several thousand communications may occur. complete duplexes through a given satellite 12. In accordance with one aspect of the system 10, two or more satellites 12 can each transport the communication is between a given user terminal and one of the gates 18. This mode of operation, which it is described in detail below, thus providing the combination of diversity in the respective receivers, which leads to increased resistance to weakening and facilitates the implementation of a smooth delivery procedure. It is noted that all frequencies, bandwidths and the like, which are described herein, are representative of only one particular system. You can use other frequencies and frequency bands, without changing the principles that are being discussed. As just one example, the feeder links between the gates and the satellites can use frequencies in a band other than the C band (approximately 3 GHz to 7 GHz, for example, the K? Band (approximately 10 GHz to 15 Hz ) or the Ka band (per encuna of around 15 GHz) The gate 18 functions to couple the communications instruments or the transponders 12a and 12b (Figure 3fl) of the satellites 12 to the telephone infrastructure segment 4. The transponders 12a and 12b include an L-band receiving antenna 12c, an S-band transmitting antenna 12d, a power amplifier in C-band 12e, a low-band amplifier in C-band 12f, antennas for C 12g and 12h band, section 12 for converting frequency from band L to band C and section 12j for conversion of frequency from band C to band S. Satellite 12 also includes a 12k master frequency generator and equipment of command and telemetry 121. Reference may also be made, in this regard, to U.S. Patent No. 5,422,647, to E. Hirshfield and CR Tseo, entitled "Mobile Communications Satellite Payload" ("Instrument for Mobile Communications Satellite") ( Serial No. 08 / 060,207). Telephone infrastructure segment 4 consists of existing telephone systems and includes public land mobile network (PLMN) 20 gates, local telephone exchanges, such as regional public telephone networks 22 (RPTN = Regional Public Telephone Networks) or other providers of local telephone services, long distance domestic networks 24, international networks 26, private networks 28 and other RPTN 30. The communication system 10 operates to provide bidirectional voice and / or data communication between the user segment 2 and telephones 32 of the public switched telephone network (PSTN - Public Switched Telephone Network) and telephones other than PSTN 32 of telephone infrastructure segment 4, or other user terminals of various types, which may be private networks. Also shown in Figure 1 (and also in Figure 4), as a portion of the ground segment 3, a satellite operations control center (SOCC = Satellite Operations Control Center *) 36 and an operations control center on ground (GOCC = Ground Operations Control Center) 38. A communication path, including a terrestrial data network (GDN) 39 (see Figure 2) is provided for interconnecting gates 18 and TCUs 18a, SOCC 36 and GOCC 38 of the ground segment 3. This portion of the communications system 10 provides 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, each of which comprises a dish antenna 40, the antenna driver 42 and the pedestal 42a, low noise receivers 44 and high power amplifiers. 46. All these components can be located inside a dome structure to provide environmental protection. Gate 18 further includes down converters 48 and up converters 50 for processing received and transmitted RF carrier signals, respectively. The downconverters 48 and the upconverters 50 are connected to a CDMR subsystem 52 which, in turn, is coupled to the public switched telephone network (PSTN) by means of a PSTN ternase 54. As an option, the PSTN could be bypassed using satellite-to-satellite links. The CDMR subsystem 52 includes a signal adding / switching unit 52a, a gate transceiver subsystem (GTS) 52b, a GTS controller 52c, an interconnection subsystem with CDMfl (CIS) 52d, and a selector bank subsystem - (SBS) 52e. The CDMR subsystem 52 is controlled by a base station manager (BSM) 52f and operates in a manner similar to a base station compatible with CDMfl (eg, an IS-95 compatible). The CDMR subsystem 52 also includes the required frequency synthesizer 52g and a 52h receiver of the global positioning system (GPS = Global Positionmg System). The PSTN interface 54 includes a PSTN service switching point (SSP) 54a, a call control processor (CCP) 54b, a visitor location register (VLR) 54c, and a protocol interface 54d, for a registration of Base location (HLR = Home Location Register). The HLR may be located in the cellular gate 20 (figure 1), optionally, in the 54th station of PSTN. Gate 18 is connected to telecommunication networks by means of a normal interface, formed through SSP 54a. Gate 18 provides an interface and connects to the PSTN by means of the Primary Rate Mode (PRI - Pnrnary Rate Interface). The gate 18 is also capable of providing a direct connection to a mobile switching center (MSC = Mobile Switching Center). Gate 18 provides fixed signaling from S5-7 ISDN to CCP 54b. On the gate side of this method, the CCP 54b forms inter- est with the CIS 52d and, therefore, with the subsystem 52 of CDMfl. The CCP 54b provides protocol translation functions for the air interface (Ifl) of the system, which may be similar to the transient standard IS-95 for communications by CDMfl. The blocks 54c and 54d generally provide an interface between the gate 18 and the external cellular telephone network, which is compatible, for example, with the IS-41 cellular systems (North American standard, AMPS) or with the GSM cellular systems (European standard). , MAP) and, in particular, with the methods specified to handle rovers, that is, users who make calls outside their base system. Gate 18 supports terminal authentication for the 10 / AMPS system telephones and for the 10 / GSM system telephones. In service areas where there is no telecommunication infrastructure, an HLR can be added to gate 18 and form an interface with signal S-7. A user making a call outside the user's normal service area (a roaming = roaming) is accommodated by the system 10, of being autorized. Since that errant can be found in any environment, a user can use the same terminal equipment to make a call from anywhere in the world, and the necessary protocol conversions are made transparently by gate 18. The 54d protocol interface is bypassed when it is not necessary to convert, for example, GSM to RMPS. It is within the scope of the teachings of this invention to provide a dedicated universal method, in the cellular gates, in addition to or instead of the conventional "A" method specified for the GSM mobile switching centers and the vendor-owner interfaces for the mobile switching centers IS-41. It is also within the scope of this invention to provide an interface directly to the PSTN, as indicated in Figure 1, as the signal path designated PSTN-INT. Full gate control is provided by gate controller 56 which includes an interface 56a for the ground data network (GDN) 39 mentioned above, and an interface 56b for service control center 60 ( SPCC). The gate controller 56 is generally interconnected with the gate 18, by means of the BSM 52 f and by means of the RF controllers 43, associated with each of the antennas 40. The gate controller 56 is further coupled to a database 62, such as a user database, satellite ephemeris data, etc., and with an input / output unit (1/0) 65, which enables service personnel to have access to the controller 56 of gate. The GDN 39 is also provided with bidirectional interfaces to the telemetry and command unit 66 (TSC) (Figs. 1 and 4). Referring now to Figure 4, the function of the GOCC 38 is to plan and control the use of the satellite by the gates 18 and coordinate that use with the SOCC 36. In general, the trends of the GOCC 38 analyzes generate traffic plans, allocate the resources of satellite 12 and the system (such as, but not limited to, power and channel assignments), monitor the operation of global system 10 and issue usage instructions, through GDN 39, to gates 18 , in real time or in advance. The SOCC 36 works to maintain and monitor the orbits, to collect the information from the satellite to the gate to enter the GOCC 38 through the GDN 39, to monitor the general functioning of each satellite., including the state of the satellite batteries, to establish the gain for the RF signal paths within the satellite 12, to guarantee the optimal orientation of the satellite with respect to the surface of the earth, in addition to other functions. As described above, each gate 18 functions to connect a given user to the PSTN for both signal, voice and / or data communications, as well as to generate data, through the database 62 (FIG. 2), for billing purposes. The selected gates 18 include a telemetry and control unit 18a (TCU) for receiving telemetry data which is transmitted by the satellites 12 via the return link 19b and for transmitting commands to the satellites 12, via the link shipment 19a. The GDN 39 operates to interconnect the gates 18, the GODD 38 and the SOCC 36. In general, each satellite 12 of the LEO constellation operates to relay information from gates 18 to the users (sending link in C band 19a to send link in S band 17a), and to relieve information from users to gates 18 (return link in L band 17b to return link in C band 19b). This information includes SS-CDM and location synchronization channels, as well as signals to control the power. Various CDMA pilot channels can also be used to monitor interference on the sending link. The ephemeris update data of the satellite are also communicated to each of T)
the user terminals 13, from the gate 18, by means of the satellites 12. The satellites 12 also function to relieve the signal information from the user terminals 13 to the gate 18, including the access requests, the change requests of power and requests for registration. The satellites 12 also relieve communication signals between the users and the gates 18 and can apply security for my unauthorized use. In functions, the satellites 12 transmit spatial artifact telemetry data, including measurements of the satellite's functional state. The telemetry current of the satellites, the commands from the SOCC 36 and the communications feeder links 19, all share the antennas 12g and 12h in the C band. For those gates 18 that include a TCU 18a, the satellite telemetry data received may be sent immediately to SOCC 36 or the telemetry data may be stored and subsequently sent to SOCC 36 at a later time, typically at the request of the SOCC. The telemetry data, whether transmitted immediately or stored and subsequently sent, are sent by the GDN 39 as packaged messages, each message in packet containing a single frame of smaller telemetry. In case more than one? OCC 36 is providing satellite support, the telemetry data is sent to all SOCCs.
The SOCC 36 has several interfacing functions with the GOCC 38. An interface function is the orbital position information, where the SOCC 36 provides orbital information to the GOCC 38, so that each gate 18 can accurately track the four satellites that can be seen in the gate. These data include data tables that are sufficient to allow the gates 18 to develop their own contact lists with the satellite, using known algorithms. The SOCC 36 does not need to know the gate tracking programs. The TCU 18a searches for the downlink telemetry band and uniquely identifies the satellite that is being followed by each antenna, before the propagation of the commands. Another interface function is the satellite status information that is reported from SOCC 36 to GOCC 38. Satellite status information includes both satellite / transponder availability, battery status and orbital information; and incorporates, in general, any limitations related to the satellite, which would prevent the use of all or a portion of a satellite 12 for communications purposes. An important aspect of the system 10 is the use of ?? - CDMA in conjunction with the diversity combination in the gate receivers and in the user terminal receivers. The diversity combination is used to mitigate weakening effects when the signals reach the user terminals 13 or the gate 18 from multiple satellites, by multiple and different path lengths. The angle of incidence receivers in the user terminals 13 and in 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 a diversity combination for the send link signals or for the return link signals that are simultaneously received from, and transmitted simultaneously through, the multiple lobes of logs. satellites 12. In this sense, the description of U.S. Patent No. 5,233,626, issued August 3, 1993 to Stephen A. Ames and entitled "Repeater Diversity Spread Spectrum Communication System" ("in its entirety") is incorporated herein by reference. Amplitude spectrum communication system, with repeater diversity "). Operation in the continuous diversity reception mode is superior to that of receiving a signal through a satellite repeater and, additionally, there is no interruption in communications in the event that a link is lost due to weakening or blockage by trees or other obstructions, which have an adverse impact on the received signal. The multiple directional antennas 40 of one of the gates 18 are capable of transmitting the send link signal (gate to the user terminal) through different beams of one or more satellites 12, to support the diversity combination at the terminals of 13. The omnidirectional antennas 13a of the user terminals 13 transmit through all the satellite beams that can be "seen" from it. user terminal 13. Each gate 18 supports a transmitter power control function to address slow weakenings and also supports block interleaving to direct medium to fast weakenings. The power control is controlled both on the sending link and on the reverse link. The response time of the power control function is adjusted to accommodate, in the worst case, a delay in round trip of the satellite of 30 milliseconds. The block interleavers (53d, 53e, 53f, FIG. 5) operate in a block section that is related to 53g encoder packet frames. An optimal tertiary tranche negotiates a larger stretch and, therefore, an improved error correction at the expense of increasing the overall end-to-end delay. A maximum end-to-end delay is 150 msec or less. This delay includes all delays including those due to the alignment of the received signal, effected by the diversity combiners, the speech encoder processing delays 53g, the interleaver delays of blocks 53d-53f, and the delays of the Viterbi decoders (not shown) that form a portion of the CDMA subsystem 52.
Fig. 5 is a block diagram of the send link modulation portion of the CDMA subsystem 52 of Fig. 2. An output of an adder block 53a feeds an agile upstream 53b frequency converter, which in turn , it feeds the adder and switch block 52a. The telemetry and control information (T8C) is also entered into block 52a. An unselected direct sequence pilot channel SS generates a waleh code of all zeros, at a desired bit rate. This data stream is combined with a short PN code, which is used to separate signals from different gates 18 and different satellites 12. If used, the pilot channel is added in module 2 to the short code and then expanded to QPSK or BPSK through the bandwidth of the ADMA RF channel. The following different PN-noise code (PN) offsets are provided: (a) a PN code offset to allow a user terminal 13 uniquely identifies a gate 18; (b)? n PN code offset to allow the user terminal 13 to identify Asingular a satellite 12; and (c) a PN code offset to allow a user terminal 13 uniquely to identify a given beam of the 16 beams that are transmitted from the satellite 12. The pilot PN codes of the different satellitee 12 have different displacements in time / phase with respect to the same PN code for pilot planting.
If used, each pilot channel that is transmitted by gate 18 can be transmitted at a power level greater or less than the other signals. A pilot channel allows a user terminal 13 to acquire the time control of the sending CDMA channel, provides a phase reference for coherent demodulation and provides a mechanism for making comparisons in the signal strength, to determine when to initiate the delivery. However, the use of the pilot channel is not mandatory, and other techniques can be used for that purpose. The Sync channel generates a stream of data that includes the following information: (a) time of day; (b) identification of the transmit gate; (c) satellite ephemerides; and (d) assigned location channel. The Sync data is applied to a 53h convolution encoder, where the data is circularly encoded and blocks are interspersed subsequently to combat the rapid weakening. The resulting data stream is added in module two to the synchronous Ulalsh code and extended to QPSK or BPSK by means of the bandwidth of the RF channel CDMfl FD. In general, the location channel carries various types of messages that include: (a) a system parameter message; (b) an access parameter message; and (c) a channel list message CDMfl. The system parameter message includes the configuration of the locator channel, the registration parameters and the parameters to aid in the acquisition. The access parameter message includes the configuration of the access channel and the data rate of the access channel. The channel list message CDMfl carries, if used, an associated pilot identification and a Ualsh code assignment. The voice encoder 53 3k encodes the voice to a stream of send traffic data in PCM. The send traffic data stream is applied to a circular encoder 531, where it is convoluted and then interleaved with blocks in block 53f. The resulting data stream is combined with the output of a long user code block 53k. The long code is used to separate different suscpptor channels. The resulting data stream is then controlled at its power in the multiplexer (MUX) 53rn, the doe module is added to the Ualsh code and then opened to QPSK or BPSK through the bandwidth of the RF communication channel CDMA FD . Gate 18 functions to demodulate the CDMA return link (s). There are two different codes for the return link: (a) the zero offset code and (b) the long code. These are used by the two different types of return link CDMfl channels, that is, the access channel and the return traffic channel. For the access channel, the gate 18 receives and decodes a download on the access channel that requests access.
The access channel message is incorporated into a long preamble, followed by a relatively small amount of data. The preamble is the long PN code of the user's terminal. Each user terminal 13 has a unique, long PN code generated by a time shifter unique to the common PN generator polynomial. After receiving the access request, the gate 18 sends a message on the send link locator channel (blocks 53e, 53i, 53j) recognizing the receipt of the access request and assigning a Ualsh code to the user terminal 13 for establish a traffic channel. The gate 18 also allocates a frequency channel to the user terminal 13. Both the user terminal 13 and the gate 18 switch to the assigned channel element and the duplex communications begin using the assigned Ualsh code (s) (which are extended). The return traffic channel is generated in the user terminal 13 by encoding the digital data circumvolutionally from the local data source or voice encoder of the user terminal. Then the data is interleaved in blocks at predetermined intervals and * applied to a 128-flry modulator and with a data download scrambler, to reduce confusion. Then the data is added to the zero offset PN code and transmitted through one or more of the satellites 12 to gate 18. Gate 18 processes the return link using, for example, a fast Hadamard transformer (FHT = Fast Hadamard T ansform) to unroll the Ualsh 128-Ary code and provide the demodulated information to the diversity combiner. The foregoing has been a description of a currently preferred embodiment of the seventh communications 10. A description will now be given of the presently preferred embodiments of the present invention. This invention is based on the invention described in U.S. Patent No. 5,223,626, to Stephen Arnés, to which reference was made above, which is entitled "Repeater Diversity Spread Spectrum Communications System" ("Spectrum Communications System"). amplitude, with repeater diversity "). In the system described in the Ames patent multiple signals may be transmitted concurrently from multiple transmitters and independent antennas to a single user receiver, by means of multiple satellite repeaters, thereby forming multiple sending paths 19a, 17a, from from gate 18, to user terminal 13. Likewise, the return paths are defined from the single-user terminal 13 to the independent, multiple gate antennas and the multiple receivers, by means of the multiple satellite repeaters. In the present invention the transmission of the signals coming from the multiple independent transmitters and the multiple antennas, is elevated to the optimum point and selected under the control of the gate 18, according to the information provided by, or for the user terminal It is being used, and also the information stored in gate 18. The selection of one or more satellite repeaters is based on information. The teaching of this invention is directed primarily to the sending link 19a, 17a, i.e., the address from the gate 18 to a user terminal 13, through one or more satellite repeaters 12. However, the teaching of this invention is also applicable to the return link path 17b, 19b, if a directional antenna means is available for the user terminal 13. Both modalities (that is, the sending link and the reverse link) are described in detail in what follows. Referring now to Figure 6, there is shown a supply system 60 with path diversity, in accordance with this invention. The gate frequency determination unit 43 sends a single traffic signal input to one or more of the various independent paths and sends them to one or more transmitters 46a, 46b, 46c, which amplify each signal on the same frequency and supernine the amplified signal to one or more corresponding directional composite antennas 40a, 40b, 40c, for transmission, simultaneously or essentially simultaneously, and with the same frequency of RF channel, to the satellite repeaters 12. However, with appropriate processing and signal combination in the user terminal 13, there may be arbitrary delays in the transmission. The receiver antennas 12h of the selected satellite repeaters receive the uplink signals (sending path 19a) (not necessarily simultaneously) and transmit the signals to ground, by means of the antennas 12d. While three satellites involved in transmitting the communication to the user terminal 13 are illustrated, it should be understood that one may be used from "satellite" repeaters 12, where "n" is equal to or greater than 2. The one or more selected transmitted signals are received at the user terminal antenna 13a and sent to the receiver for diversity combination. The user terminal receiver 13 can be constructed and operated in the manner described in the Ames patent referred to above, which has been incorporated herein by reference. It is within the scope of the invention to employ other diversity combining techniques as well. Figure 7 illustrates a portion of the path diversity supply system 60 of Figure 6, and also a path diversity selection system (PDSS) 70, which is constructed and operated in accordance with the invention. The PDSS 70 receives the inputs from the external information sources, which include the location 72 of the user terminal, the power activity 74 of the user and a type 76 of the user terminal. The user data 77 of the user's historical data are collected and organized by the database system 95 of the user's history and stored in the database 86. The data 77 of use of the historical system 77, for example, they may include an environment within which the user terminal 13 is used very frequently (e.g., urban area, rural area) and may also include the typical or average length of time the user terminal is employed to effect a call or a connection. Gate 18 has access to said information, as it is primarily responsible for managing the connections of the individual user and for gathering the information related to billing for the terminals of the individual user. The PDSS 70 includes a transmitter control unit 78 that issues control instructions 78a to the frequency determination unit 43 of the path diversity supply system 60. The control instructions 78 specify which transmitter and which pair of antennas (46a, 40a, etc.) to use to direct the traffic signals of the user 62 over specific sending links 19a, to the selected satellite repeater 12. The transmitter control unit 78 receives instructions from an instruction module 80, which is connected to a computing subsystem 82. The computer subsystem 82 determines the number of diversity paths to be provided and the type of diversity. The type of diversity can include which repeater or satellite repeaters should be used. The computing subsystem 82 can also determine other control parameters, such as the power levels to transmit. The computer subsystem 82 operates in accordance with established rules or with a fixed algorithm 84. The computer subsystem 82 receives inputs from, and operates by (a) information stored in the database 86; (b) information provided with a subsystem 88 load availability and satellite resources; (c) the position of the user, as provided by a subsystem 90 of location location; (d) the historical use of the system by the user; and (e) other sources of information that can be used to determine the need or lack of need for a diversity of trajectories. The location of the user terminal 13 is taken with reference to a propagation map 92 in the service area, also referred to herein as a communications environment map, which may also be stored in the database 86. The computation subsystem 82 , which acts on the output of the subsystem 90 for locating the position of the user terminal, and on the data from the propagation map 92 in the service area, which is stored in the database 86, is capable of determining an environment of the user terminal 13. That information about the environment of the user terminal is used to further process and make a decision regarding the selection of trajectory diversity. The utilization 74 of the power of the user terminal can be monitored and / or measured by a subsystem 94 of user activity, and can be provided to the computing subsystem 82 through the database 86, as described later. . The instruction interface 80 also provides instructions for a return link control unit 96 which, a s? once, it instructs 96a to a frequency control unit 64 in the user terminal, which is part of the path diversity supply system 60. When it works, a user terminal 13 comes into contact with the communications bus 10 and is assigned a service area that is under the control of a gate 18 having antennas 40a-40c and transmitters 46a-46c, which are establishing the diversity of traffic signals with the user. Upon contacting and / or at other specific times, including at the time of establishing a call, a type of user terminal is transmitted to gate 18, together with the electronic serial number (ESN) of user terminal 13. The type information of the user terminal can be transmitted in each telephone call or the type information of the user terminal can be stored, for example, in a user information database, in a base location register (HLR). ) or in a visitor location register (VLR), which is in gate 18 or in a terrestrial network to which the gate is connected. In any case, the information of the user's terminal type can be detected and the information 86 of the database can be communicated by some means. As a result, the type of user terminal is known in gate 18. For example, and referring again to FIG. 1, there may be voice terminals 15 mounted on the vehicle, voice terminals 14 carried in the hand, data terminals carried on the ground, terminals carried on stage 16, location and messages, and fixed user terminals 14a, or any number of other types of user terminals. Each of these types of user terminals may have different diversity requirements. For example, a user terminal 15 mounted on a vehicle that is moving at high speed in a wooded area may require the diversity of three of the satellites 12 to ensure continuity of service; while a user terminal 14 that is carried in the hand, which is located in a recreational boat in a lake, or in an open desert area, may not require any diversity. Since the types of user terminals 13 are known by gate 18, the diversity can be determined and applied as a group for all terminals of the same type. Alternatively, and in a more complex way, the computing subsystem 82 can dynamically assign diversity to the users who have access to the satellite system 10, with different types of user terminals, issuing instructions to the transmitter control unit 78, by means of the Internet. 80 of instruction. Other refinements of diversity control may be exercised, within each group of the user terminal type, if the type of terrain within which the user terminal 13 is located is known. In order to determine the type of terrain in which the user is located, it may be necessary to know the location of the user's terminal and the environmental characteristics of the user's location. The location of the user terminal can be determined in various ways. For example, the user terminal 13 can send the location information to the system 10, by means of a code entered by the operator (for example, 01 = urban, 02 = rural 03 = water, etc.). Also by way of example, the location of the user terminal can be emitted from a location location subsystem 90, such as GPS, LORAN or some other device that calculates the location of the user. Also by way of example, the system can locate the user's terminal by range or by triangulation, using signals from the constellation of satellites 12. In any case, it is assumed that the location of the user terminal is known for the location subsystem 90. the position. The location information of the user terminal, combined with the propagation map 92 of the service area, the information stored in the database 86 is operated by the computer subsystem 82 to determine and select the amount or degree of diversity of the data. the path for a given user terminal. For example, a vehicle-mounted terminal 15, traveling through a wooded area, may require the diversity of three satellites (as shown in Figure 6), while the same terminal 15, mounted on the same vehicle, q? If you travel in an open region, such as a flat or desert, you may be able to get the same level of service quality with only one satellite 12 (that is, without any diversity at all). Likewise, a terminal 14 carried in the center, located in an urban area, may require the diversity of three satellites, while the same type of terminal located in a lake or in the ocean may need only one satellite 12 to obtain the same connection quality. The propagation map 92 in the service area (see, for example, FIG. 10), which is stored in the database 86, can be implemented in a variety of ways, as with a geographic database. Alternatively, the satellite images of the cover area per gate can determine the regions of terrain aspect, based on the reflectance values. Additionally, it is known that satellite images taken in different spectral bands can be used to locate and identify regions that have certain types of vegetation, such as forests. Said images can also be included in the database 86. In this sense, seasonal variations in vegetation cover can also be factored in the method for determining diversity. For example, a user terminal located within a region identified by having a dense forest may be assigned a diversity of three satellites during the summer months, to compensate for the attenuation due to the leaves.; while the same user terminal, in the same forested region, in the winter months, may have a diversity of only two satellites assigned. It is also within the scope of the invention to employ real-time or real-time weather information, such as that provided by the Doppler radar, to determine the diversity for a given user terminal. For example, and depending on the RF frequencies that are in use, the user terminals that are known to be located within rain cells within the coverage area of gate 18, as determined by the Doppler radar images of 1. The coverage area of gate 18, may have its level of diversity increased with respect to those terminals not currently located within a rain cell. In general, well-known types of computer techniques are used to develop detailed environmental maps, which include vegetation, natural aspects of the terrain, suburban and urban development, as well as roads, farming areas, industrial areas and other objects. human origin These image maps, when combined with other database information, such as the user terminal type, provide detailed information about the reception and / or transmission environment of the terminal. In this way, the computer subsystems 82 are enabled, which use the rule series 84 and which act by information of the database 86 and the known location of the user terminal from the location location sub-system 90, to feed to the individual station terminal, by means of individual user terminal instructions to the transmitter control unit 78, so as to control the number of gate antenna / transmitter pairs q and send a traffic signal transmission (19a, 17a) to the receiver of the user terminal by means of the selected number of satellite repeaters 12. Another refinement in the path diversity control is implemented by a knowledge of the historical use of the power by the user terminals 13. For example, in most mobile communication systems using satellites, the individual traffic signals of the The user's terminal are actively controlled in terms of power, so that there is sufficient margin to overcome weakening and blocking, on a link-by-link basis. Said power control circuits operate on both the send and return links and may be open or closed circuits. In any case, the power control circuits can be monitored and the data can be retrieved by the gate 18 which is used to determine the historical utilization of power and, consequently, the environment of the user terminal. It is possible to determine, in a general way, the type of blockage or weakening that is being experienced. For example, it can be deduced that a bond that is blocked (has an extremely deep loss of force) for a terminal 14 carried out for a few minutes, at a time, is caused by a building or some other object opaque to radio frequency ( RF). On the other hand, a sequence of weakening that varies rapidly from substantially zero to a loss of deep force can mean a vehicle moving through an environment with many trees. These data related to historical power control are used to make decisions regarding the supply of trajectory diversity. Likewise, some users may historically use more power per call than others, which leads to a desire to provide, or to deprive that user terminal of diversity, according to the need. These historical power control data may be of an average long-term or short-term nature.
The methods for selecting the diversity of trajectories, described above, can be used separately or can be combined in multiple ways, and can be assigned dynamically or dynamically. For example, the user terminals 13 can be selected essentially to also supply them with the diversity of "all available satellites" effectively bypassing, in any way, the system of selection of the diversity of trajectories. Alternatively, by instructions from the load subsystem 88 and from satellite resources, the computer subsystem 82, under the control of rule set 84, may determine that selective path diversity is not required in order to save energy or manage the assignment of the FDM frequency of the satellites 12. The computation subsystem 82, under the control of the rule series 84, then decides, on the link-by-link basis, or alternatively on the basis of a user terminal group, in which ode of diversity of trajectories to operate. The various refinement modes of the trajectory diversity control, which were described above, can be used individually or in any combination, as necessary, to achieve the goals of the instructions of the satellite load and resource subsystem 88. In such a way, it is an aspect of this invention that the user terminals 13 are actively contro in their diversity, in a very similar way as the user terminals are contro in power, through a control circuit of the diversity of trajectory, open or closed circuit, used to provide almost instantaneous changes in the diversity of the link, in response to the information received. The capacity of satellite communications systems is generally limited to both the bandwidth and the available power on the satellites. The use of bandwidth and power availability depend, in part, on the diversity provided to user terminals 13 in the system. While the foregoing discussion generally refers to the improvement in the reception of signals by the user terminals 13, the opposite effect can also be achieved by the invention described herein. For example, the path diversity control of the individual user terminals 13, the user terminal subgroups 13 or all of the user terminal groups 13, can be used to dynamically increase the capacity of the system and / or to affect the use of system power. The instructions from the upload to 88 of satellite load and resources, driven by the series of rules 84 in the computing subsystem 82, can also be used to control the use of the individual satellite resources. Up to now the discussion has generally dealt with the sending link, that is, the communication path from gate 18 to user terminal 13, by means of one or more satellite repeaters 12. The discussion that begins will refer, this time, to the reverse or return link. The return link is defined in the following manner and as shown in Figure 8. A user terminal 13 returns a single input and sends it to a transmitter, which amplifies the signal and supplies the amplified signal to its antenna 13a for transmission simultaneously, at the same frequency, to the satellite repeaters 12. The receiving antennas 12c of the satellite repeaters receive the signals, not necessarily simultaneously, and transmit the signals to ground through the transmission antennas 12g ( see also Figure 3fl). The transmitted signals are received in the gate 18 by the receiving antennae mdependent 40a-40c and are sent to their respective receivers 44a-44c. Then you can process the received signals and you can combine them as described, for example, in U.S. Patent No. 5,233,626, which has been incorporated herein by reference. The return link can be used to determine the power activity 74 of the user terminal (Figure 7), although the contr-ol activity of the send link power can be used for this purpose as well. Likewise, the return link can be used to transmit the user terminal type 76 (Figure 7), although this information can be derived from a database of inactive or active users in the system, such as by correlating the electronic serial number (ESN) of the user terminal with an associated and predetermined user terminal type. The return link can also be used to transmit the location 72 of the user's position (Figure 7) for use in the diversity decision making, by the computation subsystem 82. In this case, the user terminal 13 transmits a signal in this information carrying the return link, which can be used by the gate 18 to determine the location of the user terminal 13. Alternatively, the user terminal 13 can transmit its location by the use of some code. In another embodiment of this invention, any of the types of radio-location systems of the well-known types (such as the various GPS location location devices) can be used to determine the location of the user terminal 13, after which the information 72 of the location of the user terminal is transmitted by the return link, to the gate 18 and, from there, to the station 90 of location location (figure 7). As mentioned previously, the return link may also have diversity selectivity in accordance with the teachings of this invention, as long as the user terminal 13 has the capability to simultaneously address signals to one or more satellite repeaters 12. In that case, the operation of the system involves the cooperation of the gate 18 and the user terminal 13, in the following manner. As described in more detail below, the user terminal type 76, the location 72 of the user's position and the activity 74 of the power of the user terminal are determined and processed by the computer subsystem 82 and instructions are issued to the instruction interface 80. The instruction interface 80 decodes the instructions and generates control signals suitable for the transmitter control unit 78 and the return link control unit 96. In this case, the control signal generated by the return link control unit 96 causes a signal 96a to be formatted and to be supplied to the terminal frequency control unit 54 of the supply system 60 of the path of diversity. The terminal frequency control unit 64, in turn, generates a control signal containing the information that it is necessary to control the antenna / amplifier combination in the user terminal 13. This signal is sent to the receiver of the terminal of the terminal. user 13, by the send link. As shown in Figure 9, the control signal 102 is received at the user terminal 13 and is directed to an antenna selector 104, which controls the antennas 13a, 13a ', 13a ", etc., to obtain The desired results, that is, in this mode, the control over the antennas 13a-13a "of the user terminal 13 and, consequently, the control over the diversity of the return link path, is achieved by remote control from gate 18, using the send link as a control link. Reference is now made to Figure 10 to show a portion of an exemplary service area propagation, or communication environment map 92. On this digitized, exemplary map, which can be derived from satellite images of the gate service area, is located a lake region, a forest region, a rural region and an urban region. These different regions can be classified into three general types of environmental regions (ER), according to a level of trajectory diversity that is anticipated to be given to a stationary user terminal 13, with an adequate and acceptable link quality. For example, the lake region is designated as ER1, which corresponds to no diversity (that is, only one satellite repeater). The rural area is designated ER2, which corresponds to an intermediate level of path diversity. The forest region and the urban region are both designated ER3, which may correspond to a maximum level of diversity available for the trajectory (ie, the communications link is established through as many satellites 12 as possible, depending on the load of the system and other criteria). Graphed on map 92 there are the current locations of 14 active user terminals (UT1-UT14).
Assuming, as is the simplest case, that three satellite repeaters 12 are serving that all user terminals 13 are of the same type and that the other factors, such as the historical power control information, are not taken into account. , the seasonal variations, the local meteorological conditions, etc., then one of the satellite repeaters 12 is assigned to UT1; is assigned to UT3 and UT4 doe of the satellite repeaters, and is assigned to each of UT2 and UT5-14 three of the satellite and repeaters 12. It can be seen that it is not obtained, by automatically assigning maximum path diversity considerable savings in satellite energy consumption, as well as conservation of the number of RF channels required and a general increase in the total capacity of the system, are available to user terminals UT1, UT3 and UT4. Additionally, according to the invention, the profile of the relatively static system described hitherto can be extended to the more typical dynamic case, while at the same time the diversity of trajectories supplied to the user terminals 13 is still at the optimum point. For example, if UT2 is a mobile terminal 15, mounted on a vehicle, then, upon detecting that the location of UT2 has changed from ER3 to ER2, the diversity of the assigned trajectory in real time or in substantially real time can be changed from three satellitee to two, at the same time that the same link quality perceived by the user is maintained.
Conversely, if the location of UT4 changes from ER2 to ER3, the assigned path diversity of two satellites can be changed to three. Further, if it is known that vanes of UT 5-14 are fixed user terminals 14a, which are assumed to have antennas that are located in a region free of blocking signal obstructions, then those user terminals may have assigned only one satellite, whether they are located within a portion ER3 of the gate 18 service area. Also as an example, the forested region can be designated as an ER3 region during the months of May to October, and can be designate an ER2 region during the months of November to April. The rule set 84 of FIG. 7 determines the path diversity level for the user terminals UT1-UT14, as previously described. The series of rules 84 can be implemented as a sequence of type IF-THEN-EL? E (if-then -or well) of the logical exposures. For example, the following is just a suitable modality for a portion of rule set 84, to determine a diversity level (DL) for user terminals 13. IF TYPE of UTj = PORTABLE and YES LOCATION of UTj = ER1 THEN DL = MINIMUM 0 IF THE LOCALIZATION OF UTj = ER2 THEN DL = INTERMEDIATE OR IF THE LOCALIZATION OF UTj = ER3 THEN DL = M XIMO OR IF TYPE OF UTj = FIXED THEN DL = MINIMUM OR GOOD
YES TYPE OF UTi = DATA TERMINAL y YES LOCALIZATION OF UTj = ER1 THEN DL = MINIMUM OR YES TYPE of UTi = DATA TERMINAL y YES LOCALIZATION OF UTj = ER1 THEN DL = INTERMEDIATE OR IF THE LOCALIZATION OF UTj = ER2 OR ER3 THEN DL = MAXIMUM etc. The type of data terminal of the user terminal 13 illustrates the utility of the invention in assigning a level of diversity based on both the type of terminal co or the location. For example, it may be desirable to automatically assign a higher diversity to a user terminal that is identified as a data terminal, or to a voice terminal, which is identified in the course of a data transmission, so as to provide a margin additional to avoid an erroneous transmission of data. As previously described, other criteria can be considered in the series of rules 84, when a level of diversity is determined, such as the historical information of the energy control, the historical use data 77., local weather conditions and any other factors that are related to, or may influence, the quality of the link. It should be noted that the determined level of diversity for a given user terminal may differ from the actual diversity level supplied to the user terminal. For example, if only two satellites 12 are currently in view in the gate service area, then a minimum level of diversity can be a satellite, while the intermediate and maximum diversity levels can both be set on two satellites, usually one on the other. , even if only one satellite is visible to the user terminal 13, the gate 18 and the user terminal 13 may be able to use signals from two overlapping media. Since the geometry of the satellites is known, this invention can control and employ transmissions of more than one beam. Finally, for example during periods of increased user demand, and assuming that three satellites are currently serving the gate area, the intermediate and maximum diversity levels can still be set on two satellites. The translation of the determined diversity level to a real diversity allocation for a given user terminal 13, or the class d terminales user terminals, is achieved by computing subsection 82, in cooperation with the subsystem 88 of satellite load and resources . Figure 11 is a flow chart of a method of this invention. In block fl a user terminal is connected or, if it is already connected, initiates a call or is called. In block B, the type 76 of the user terminal is determined and in block C the location 72 of the user terminal is determined. In the optional block D, other user terminal parameters are determined, such as the historical power control information 74, the historical use 77, the weather conditions at the determined location of the user terminal, etc. In the block E the computational sub-system 82 determines, through the database 86 and the location location subsystem 90, the level of diversity for a user terminal 13. The level of diversity is determined in cooperation with the rule set 84, the location 72 of the user's poem, the user terminal type 76, the optional information related to the user terminal, such as the energy activity 74 of the user. terminal, the propagation map 92 in the service area and, according to the load and resource system of satellite 88. In block F the call is established with a diversity level selected by means of the instruction interface 80 , the transmitter control unit 78, the path diversity supply system 60 and, optionally, through the return link control unit 96 and the terminal frequency control unit 64. In block J the system senses and reports the increased / decreased energy control activity and, after a suitable delay, in block K, the path diversity increases or decreases accordingly. In block G a determination is made if the call is complete. If not, the control returns to block C for a type of user terminal that is capable of movement, to update the position of the user terminal and to modify the level of path diversity (block E), if appropriate. If so, in block G an optional step (block H) is executed to store or connect selected user terminal parameters, such as the terminal power activity, the last location of the user terminal, etc. In block I the method ends for that user terminal. It can be appreciated that the teaching of this invention provides several important advantages for any type of communication system that employs combinations of diversity through intermediate signal repeaters. That is to say, the teaching of this invention is not limited to use only with the SS-CDMA type of the LEO satellite communication system 10 which is generally shown in Figures 1-5. Rather the teaching of this invention is applicable to other types of communication siether that use, for example, terrestrial repeaters either alone or in combination with satellite repeaters (LEO or geoschronic). The teaching of this invention is also applicable to other types of access, such as TDMA, which use diversity in some way. Thus, although the invention has been shown and described by the invention with respect to its preferred embodiments, those skilled in the art will understand that changes in form and detail can be made here without departing from the scope or spirit of the invention. the invention.
Claims (38)
1. - A communication system, characterized in that it comprises: a plurality of communication signal repeaters; A communication signal transmitter having a plurality of antennas for selectively transmitting a communication signal to at least one of the plurality of communication signal repeaters; a communication signal receiver for receiving a communication signal from the communication signal transmitter, by means of said at least one communication signal repeater; and control means responsive to the information specifying at least one location of the receiver of the communication signal and additional information describing a stored map of a propagation environment of the communication signal at the location of the signal receiver. communication, to specify a number of repeaters of the communication signal that must be used in the repetition of a communication signal that is transmitted from the transmitter to the receiver, through the specified number of repeaters of the communication signal.
2. A communication system according to claim 1, further characterized in that the control means responds additionally to the information that specifies a type of receiver of the communication signal to specify the number of repeaters of the communication signal that they must be used in the repetition of the communication signal that is transmitted from the transmitter to the receiver.
3. A communication system according to claim 1, further characterized in that the receiver is a component of a trans-receiver that has a transmitter that is remotely controlled in s? power; and wherein the control means additionally responds to the information specifying a power control history for the transceiver of the trane-receiver, to specify the number of repeaters of the communication signal to be used in the repetition of the signal of communication that is transmitted from the transmitter to the receiver.
4. A system according to claim 1, further characterized in that the additional information includes the stored information that specifies a characteristic of RF energy propagation that is associated with an environment within which the signal receiver is located. communication.
5. A system according to claim 1, further characterized in that the plurality of communication signal repeaters is located on board individual satellites from among a plurality of satellites orbiting the earth.
6. - A system according to claim 5, further characterized in that the plurality of satellites orbiting the earth forms a portion of a constellation of low Earth orbit (LEO) satellites.
7. A communication system according to claim 5, further characterized in that the control means additionally responds to information specifying a current availability of the plurality of satellites orbiting the earth, to specify the number of repeaters of the signal of communication to be used to repeat the communication signal that is transmitted from the transmitter to the receiver.
8. A communication system according to claim 5, further characterized in that the control means additionally responds at least to information specifying a current availability of the plurality of satellites orbiting the earth, to specify the number of beams of the repeaters of the communication signal to be used to repeat the communication signal that is transmitted from the transmitter to the receiver.
9. A communication system according to claim 1, further characterized in that the transmitter is a component of a trans-receiver of the ground station having a receiver based on the ground, to receive user communications through said at least one repeater of the communication signal; wherein the receiver is a component of a user ans-receiver having a transmitter and an antenna for directing a transmission to at least one of the repeaters of the communication signal, which is to be relayed to the receiver based on ground; and wherein the control means selects at least one of the repeaters of the communication signal to relieve communication from the use trans-receiver to the ground-based receiver; and further including means for transmitting a message to the user trans-receiver to control the antenna of the user transceiver so that it transmits communication to a selected repeater of said repeaters of the communication signal.
10. A communication system, characterized in that it comprises: a plurality of repeaters of the communication signal; a communication signal transmitter having a plurality of antennas for selectively transmitting a communication signal to individual repeaters among the repeaters of the communication signal; a receiver of the communication signal for receiving a communication signal from the communication signal transmitter, through at least one of the repeaters of the communication signal; and control means responsive to information specifying at least one type of receiver of the communication signal, to specify a number of said repeaters of the communication signal to be used to repeat a communication signal that is transmitted from the transmitter to the receiver.
11. A communication system according to claim 10, further characterized in that the control means responds additionally to the information specifying a location of the communication signal receiver to specify the number of repeaters of the communication signal that has to be transmitted. be used to repeat the communication signal that is transmitted from the transmitter to the receiver.
12. A communication system according to claim 10, further characterized in that the control means responds in addition to the information specifying an environment of the receiver of the communication signal to specify the number of repeaters of the communication signal that has to be used to repeat the communication signal that is transmitted from the transmitter to the receiver.
13. A communication system according to claim 10, further characterized in that the control means responds additionally to the information that specifies a historical use of the system by the receiver of the communication signal, to specify the number of repeaters of the communication signal that is to be used to repeat the communication signal that is transmitted from the transmitter to the receiver.
14. A communication system according to claim 10, further characterized in that the receiver is a component of a transceiver having a transmitter that is remotely controlled in terms of its power; and wherein the control means additionally responds to the information specifying an energy control history for said transceiver of the transceiver to specify the number of repeaters of the communication signal to be used to repeat the communication signal. which is transmitted from the transmitter to the receiver.
15. A system in accordance with the claim 11, further characterized in that the information specifying the location of the receiver of the communication signal includes information specifying a feature of the RF energy propagation that is associated with an environment within which the receiver of the communication signal is located.
16. A system according to claim 10, further characterized in that the plurality of repeaters of the communication signal consists of a plurality of satellites orbiting the earth.
17. A tank according to claim 16, further characterized in that the plurality of satellites orbiting the earth forms a portion of a satellite constellation of low terreetre orbit (LEO).
18. A communication tank according to claim 16, further characterized in that the control means additionally responds to information specifying a current availability of the plurality of satellites orbiting the earth to specify the number of repeaters of the signal of communication that is to be used to repeat the communication signal that is transmitted from the transmitter to the receiver.
19. A method for operating a satellite communication satellite, characterized in that it comprises the steps of: initiating a communication between a user terminal and a terrestrial station, by means of at least one repeater of the communication signal, satelite; determine the location of the user terminal within an area served by the ground station; and selecting a number of satellite repeaters for the communication signal, to relieve communication between the user terminal and the ground station; the selected number being a function of at least the determined location of the user terminal and the information describing a stored map of a propagation environment of the communication signal at the determined location of the user terminal.
20. A method according to claim 19, further characterized in that the step of selecting includes a step of determining, according to the information that describes? N stored map of a propagation environment of the communication signal, a characteristic of propagation of RF energy that is associated with the determined location of the user terminal.
21. A method according to claim 19, further characterized in that the selection step includes a step of classifying the user terminal in terms of type.
22. A method according to the claim 19, further characterized in that the selecting step includes a step of considering a power control history of the user terminal.
23. A method according to claim 19, further characterized in that the step of selecting includes a step of considering a current availability of satellite repeaters for the communication signal.
24. A method according to claim 19, further characterized in that the step of selecting includes a step of considering a historical record of use of the system, of the user terminal. 25.- A method according to the claim 19, further characterized in that the communication is bidirectionally relieved as an amplitude spectrum communication signal, of multiple access with code division, between the user terminal and the ground station. 26.- The method in accordance with the claim 19, further characterized in that it further comprises the steps of: receiving communication with the user terminal; the communication being received by means of different communication paths, associated with the individual repeaters of the selected number of satellite repeaters for the communication signal; equalize at least the phase shifts and the delays of the received communication, from each of the different trajectories to provide a plurality of equalized communication signals.; and combining the equalized communication signals to a composite communication signal received. 27. A method for operating a satellite communication satellite, characterized in that it comprises the steps of: initiating a communication between a user terminal and a terrestrial station, by means of at least one satellite repeater for the communication serial; classify the user terminal in terms of a type of user terminal; and selecting a number of satellite repeaters for the communication signal, to relieve communication between the user terminal and the ground station; the selected number being a function of at least the type of the user terminal. 28. A method according to claim 27, further characterized in that the step of selecting further includes a step of determining a location of the user terminal within an area served by the ground station. 29. A method according to claim 28, further characterized in that the step of selecting includes a step of determining the characteristics of the RF energy propagation that is associated with the determined location of the user terminal. 30. A method according to claim 27, further characterized in that the step of selecting includes a step of considering a power control history of the user terminal. 31. A method according to claim 27, further characterized in that the step of selecting includes a step of considering a history of the use of the system, of the user terminal. 32. A method according to claim 27, further characterized in that the step of selecting includes a step of considering a satellite repeater availability for the communication signal. 33.- A method in accordance with the claim 27, further characterized in that the communication is bidirectionally relieved as an amplitude spectrum communication signal, with code division multiple access, between the user terminal and the ground station. 34. A method in accordance with the claim 27, further characterized in that they additionally comprise the steps of: receiving communication with the user terminal; the communication being received through different communication paths, associated with individual repeaters of the selected number of satellite repeaters for the communication signal; equalize at least the phase shifts and the delays of the communication received from each of the different trajectories, to provide a plurality of equalized communication signals; and combining the equalized communication signals to a mixed communication signal, received. A method for operating a satellite communication system, characterized in that it comprises the steps of: initiating a communication between a user terminal and a ground station, by means of at least one satellite repeater for the communication signal; selecting at least one satellite repeater for the communication signal, to relieve a return link communication between the user terminal and the ground station; and transmitting a message from the ground station to the user terminal via a sending link; the message that controls the user terminal to transmit the return link communication through the rnenoe the selected repeater of the satellite repeaters for the communication signal; wherein the step of selecting includes a step of determining a location of the user terminal and accessing a database of signal propagation apa d, which stores information describing a propagation environment of the communication signal in the determined location of the user terminal. 36.- A satellite communication system, characterized in that it comprises: a plurality of communication satellites; a terrestrial station comprising a transceiver for transmitting and receiving communications signals with individual satellites of said plurality of communication satellites; at least one user terminal comprising a receiver to transmit and receive communication signals with individual satellites of the plurality of communication satellites; the ground station also comprising a database of related information < : on the user terminal, which includes information specifying, for individual user terminals, at least one type of user terminal; said database also storing information that is descriptive of an RF propagation characteristic of one or more regions within a service area of the ground station; said ground station further comprising control means that are coupled to the database and a series of rules to determine a number of communication satellites to relieve communication between the individual terminals of said user terminals and the ground station; including the ground station means for determining a location of individual terminals, of said user terminals; and wherein the control means determines the number of communication satellites in accordance with at least one of a type of user terminal, a user terminal location and an RF propagation characteristic, which is associated with a location of the terminal of user. 37. A satellite communication system according to claim 36, further characterized in that the database additionally stores information that is descriptive of the historical power control activity of the user terminal. 38.- A satellite communication system in accordance with claim 36, further characterized in that the plurality of communication satellites comprises a Ualker constellation of low earth orbit satellites, and wherein the communications are bidirectionally transmitted as multiple access amplitude spectrum communication signals, between a trans-terminal receiver of the user and the terrestrial trans-receiver, through at least one of the plurality of communication satellites.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US46352095A | 1995-06-06 | 1995-06-06 | |
| US463520 | 1995-06-06 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| MX9709493A MX9709493A (en) | 1998-06-28 |
| MXPA97009493A true MXPA97009493A (en) | 1998-10-30 |
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