Satellite multiplex communication network based on frame relay protocol and method for using the same

Any interested person has the right to file in writing and motivated, at OSIM, a request to revoke the decision to grant the patent. Within 6 months of its publication

RO 119760 Β1

The present invention relates to a multiplex satellite communications network, based on a raster retransmission protocol, and to a method of using it, used in a satellite communications system, which uses such a network. retransmission protocol from a ground interface station, to produce a full retransmission of the rake, which can bless the signal between a plurality of terminal devices (with different bandwidths), including multiple audio (voice) circuits, for any of the network stations.

It is known to increase the availability of affordable satellite communications services and the diversity of narrowband (voice / data) and broadband (video) devices, put to the benefit of users of broad spectrum communications systems, which has led to high-end architectures. them that can be conceived in relation to the structure of the connection and how to use them by the subscribers. This diversity of equipment types and signal processing capacity have led to the desire to have local area networks (LANs), limited to subscribers to basic terrestrial systems, restricted as a geographical area, capable of encompassing services. on a larger scale, they use satellite transmission equipment to connect terminal devices to widely dispersed office equipment.

In order to facilitate inter-office communications, it is preferable to have such satellite-based systems, configured as full retransmission networks, illustrated in the diagram in FIG. 1, wherein any terminal device 10 (including in the illustrated but non-limiting example, four ground stations 11,12,13,14), which have a direct connection 20 (via a relay satellite 30) to any other terminal device 10 from the network. The connection between said terminal device 10, which is accessed by an interface associated with the station and a second terminal device accessed by another interface of the station, can be made by providing each ground station with a multiplexing-demultiplexing subsystem that operates the transmitted controllable messages. from any terminal device (audio, video, data equipment), by a remote connection and distributes the received messages to the terminal devices of specific destination.

A typical multiplexing system that can be used would involve time division multiplexing (TDM) and demultiplexing whereby an unchanged number of bits for each user port would be allocated along with a fixed trace of information. The size of the trace (the total number of bits) can be determined by the number of access ports, by the flow of this information and by the number of traces transmitted per second. The number of TDM tracks per second determines the maximum data transmission speed. The data transmission speed includes the total data flow to the user's access ports, plus the additional tracing.

The interfacing of said terminal devices with the TDM subsystem can be accomplished by means of the access multiplexer switch, associated with the respective multiplexer and demultiplexer units of the ground station, each switch being configured for an equal number of data communication equipment (DCE) access ports. and data terminal equipment (DTE), so as to ensure full array efficiency between DCE and DTE access ports. The format and speed at the access ports (DCE to DTE) must be correlated; however, matrix switches can usually translate between different physical and electrical characteristics.

A problem associated with such a TDM matrix switch of the designed architecture of a ground station is the fact that these terminal connections to the terminals, involve specific connections of the access ports, which remain stable, unless the system is

RO 119760 Β1 physically reconfigured. As a result, in such a system, very limited selectivity is allowed for voice calls, because only point-to-point connections can be made between the voice multiplexers and not with the voice circuits themselves, which connect to the multi-3 voice plexors. In addition, current TDM systems are very sensitive to timing and network synchronization, as long as no phasing is performed. A standard 5 timing source of the network is required for all network subsystems. Also, because the power supplies of the multiplexer and the matrix switch components are not the same, different control and monitoring mechanisms are required for each part of the equipment. Added to this requirement is the fact that due to the unique nature 9 of the simplex data stream, the required multiplexer / demultiplexer is not a serial product. Lastly, the cost of such a system is substantial, since each access port switch, as well as the multiplexer and demultiplexer components, should have been purchased separately. 13 According to the present invention, which aims to ensure the integral transmission of the trace, for a relatively small number of network stations (of the order of 16 or less, 15 as a non-limiting example) is successfully addressed to the interface architecture, based on a protocol for retransmission of the creek, of a ground station. The fundamental component of this 17 architecture is a switch based on a raster retransmission protocol or a simple raster retransmission switch, which consists of a recently introduced 19-type multiplex communication component for use in voice / facsimile multiplex communications applications. (/ fax) and using a standard interface of the retransmission network, to describe the multiplexing of the virtual access ports opposite to a single physical accessible communication port. The standard trace retransmission interface is based on the successive transmission and reception 23 of the individual packets or traces of information through an access port, the respective digital data trace containing additional control bits and addresses for routing and 25 for elemental and error detection. flow control.

In the new configuration of the ground station, according to the present invention, the 27 relay relay switch is accessed, through a first set of access terminal ports, by several local terminal devices, which may comprise equipment, respectively 29 signaling, video, data and voice. A voice signal path conveys voice signals in digital form with low transmission power, such as, for example, a signal encoding speed of less than 10 Kbit / s, to and from a voice signal multiplexer, to interface the voice traffic, with a plurality of voice signaling circuits, which are selectively accessible via the multiplexer. The voice signaling path also transmits call monitoring signals, including ringtone detection, busy circuit selection, call connection and end-call connection control, and signal position. The voice signal multiplexer is operative for adding and decoding the selectivity of the information from the terminal device, to the area of ​​the address field of the rake, processed through the raster relay switch. 39

Also associated with the relay relay switch are one or more data links that can be coupled to a synchronous two-way data terminal device, providing, for example, signaling a data rate of 256 Kbit / s. An additional port of access of the relay relay switch can be coupled via a path 43 for broadband signals, such as a video conference call terminal. Video and voice signals, associated for teleconferencing, can be in digital form and compressed, for example, in a single data stream with a total data flow of 112 to 384 Kbits / s.

RO 119760 Β1

Due to the bandwidth required by the video conferencing capability, the video communication access port of the retransmit switch is intended to be used only occasionally and may require one or more signaling channels to be closed during the teleconferencing period.

By using the address and control fields through a connection control procedure, the relay relay switch can be dynamically configured to provide a multilayered addressing and selectivity (filtering) device, thus allowing point-to-point connection of multiple devices. terminals, such as a plurality of voice circuits served by the multiplexer unit of the voice circuit, to which an access port is coupled. The selection codes on the bus or on the side of the station's signal voice path are translated into trace retransmission addresses (data connection paths identifiers), which are added to each data transmission path for network routing. With this additional information routing arrangement, audio connection is now accessible between any two voice terminal devices (eg buses) in the network.

On the side of its satellite path, the relay relay switch is accessed through a multitude of modulation and demodulation circuits contained in the modulation / demodulation unit. To ensure full transmission of the trace between the multiple ground stations of the network, the modulation / demodulation unit circuits include a single transmission modulator and a plurality of receiving demodulators. The respective modulator and demodulator components may contain PSK signaling units, using for example BPSK / QPSK / MSK (data speed dependent) modulation. The modem unit is coupled to an associated RF transmitter-receiver unit, which in turn is coupled to an antenna unit associated with the satellite, for transmitting the transmission channel signals to the relay satellite and receiving the satellite receiving channel signals.

In order to optimize the flow traffic on the diversity of the terminal devices (video, data, voice) served by the interface based on the retransmission of the track, according to the present invention, the steering control mechanism, used by the microcontroller of the retransmission switch, includes a phasing of the priorities, which provides a variety of staggering levels for delay delay control via the ratchet relay switch. Voice traces are assigned the first priorities, video calls for teleconferencing, the next high level of priority, and data traces are assigned the last priorities. The staggering mechanism is characterized in such a way that during the normal operation, the retransmission switch will not have to offer more traffic than it can support the entire remote channel. Priority scaling does not have any impact on the succession of transmitted tracks. Where the given load increases or the channel error rate exceeds the prescribed limits, the priority scaling mechanism becomes active, reducing the impact of the load, first on the video signal traffic for teleconferencing and then on the voice signal traffic.

Because in a trace retransmission network, each ground station continuously monitors each receiving channel for the traces of the messages addressed to it, it is desirable to provide a mechanism for reducing the auxiliary signal precession that may be. used for the data network that does not have a terminal device served by that ground station. Parameters of the port retransmission switch's access port configuration define a bit frame (mask), which is used by the microcontroller to filter, selectively remove, or let pass traces based, in whole or in part, on the first bit of the address of the retransmission of the rake. This bit frame feature only allows traces received from parallel channels of

EN 119760 Β1 back, which are intended for one or more terminal devices, served by the ground station 1, to be accepted and processed by the ratchet relay switch. This preliminary filtration reduces the processing load and increases the efficiency of the steering via the 3 retransmission switch.

The addressing and routing mechanism used by the microcontroller of the 5 retransmission switch of the rake, also introduces, together with the ratchet retransmission collector, an indexed bit of eligibility which means for the retransmission network of the tracer, if, during the agglomeration period, this trace can be initially given to one side, or not, in the attempt to ease the agglomeration situation. As a result of the potential agglomeration of the described system 9, in the filtering and scaling mechanisms of the priorities presented above, a predetermined identifier of the data path connection can be used to force the appropriate 11 bit of eligibility from the retransmission collector of the data. trace to bit 1 for all traces using this special data path identifier. This constraint 13 of the indexed bit of eligibility to bit 1 with the help of the data path connection identifier, provides an additional level of control of the traces that originate in the devices 15 terminals, which may be unable to introduce the indexed bit themselves. eligibility.

The following is an example of an embodiment of the invention, in connection with FIG. 1 ... 6.17 which represents:

FIG. 1, in the form of a diagram, a satellite transmission network, based on a satellite, 19 in which any terminal device in the network has a direct connection via satellite to any terminal device in the network; 21

FIG. 2, in the form of a diagram, the architecture of the interface of a ground station based on a raster retransmission protocol in accordance with the embodiment of the present invention;

FIG. 3, the field format of a frame retransmission frame, and 25

FIG. 4, 5 and 6, details of the respective address, of the data path connection identifier (DLCI - data Hnk connection identif ^) and of the fields of the 27 trace verification sequence (FCS - frame checksequence) of the retransmission format of the trace according to fig. .3.

Before describing in detail the specific interface of the ground station based on a raster retransmission protocol, according to the present invention, it should be noted that the present invention first consists of a new structural combination of components and circuits. 31 conventional signal processing knives (commercially available), and not in a particular detailed configuration. In accordance with the present invention, the structure, control and arrangement of these circuits and components have been illustrated in the drawings, to be readily understood, in the form of block diagrams, indicating only their specific details, which are relevant to the present invention, so so as not to hide the disclosure of the structural details, which will be quickly visible to those skilled in the art, with the help of the accompanying description. 37 Thus, the block diagram of the figures does not necessarily present the technical arrangement of the physical system structure, but is intended to first illustrate the main components of the system structure, in an advantageous combination, by which the present invention can be understood more quickly. . 41

Referring now to FIG. 2, according to the present invention, the architecture of the ground station interface based on a creep retransmission protocol, is illustrated in diagram 43 containing a switch 110, based on a creep retransmission protocol (or a simple creep retransmission switch). ), having a plurality of bidirectional access gates, 45 for signal coupling and serving to control the signal transport interface, which are coupled to a plurality of terminal devices, with modulator and demodulator components associated with an RF transceiver for satellite communication. 49

RO 119760 Β1

More in detail, the relay relay switch 110 first has a plurality of physical devices, or terminals, ports 112, which are coupled to a plurality of local terminal devices, via the paths of the respective terminal device, such as a voice signal path. multiplexer 130, a plurality of data paths 140,150 and a video path 160. The voice signal path 130 carries the voice signals in digital form at low speed, with a coding speed of less than 10 Kbit / s, with the echo suppression and the minimum delay of stepping up to, and from, the voice signal multiplexer 135. The multiplexer The voice signal 135 is in turn coupled with a plurality of voice signaling circuits. The access ports of the multiplexer 135, which provide the connection between one or more voice signaling circuits and the voice signal path 130, effectively have virtual access gates to the relay relay switch 110, because the path 130 is physically connected to the a single port of access of the multiplexer 135 and not to the terminal devices themselves.

For the signals arriving from the respective voice circuit, the multiplexer 135 is operative for the pair signals transmitted selectively from this terminal device of the voice circuit (eg bus circuit), to the voice signal path 130. During the multiplexing of such a voice circuit selected for the voice signal path 130, the multiplexer 135 provides the information identifying the data path connection (virtual access port address), as part of the address field of the call message signals, these being delivered to the switch. of the retransmission of the rake. The destination address field contains a terminal device code (for example, a common dialed number), the c code serves the voice circuit multiplexer through a destination station and uses to control the demultiplexing of the voice signals of the called terminal device.

Similarly, during the demultiplexing of such a call brought from the relay relay switch 110 via the voice signal path 130, the multiplexer 135 decodes the information of the data path connection identification as part of the address field of the call message signals, these being delivered to the relay relay switch so as to directly control the call to the destination terminal device. Also, conventional call monitoring signals, including call tone detection, busy circuit selection, call connection and end-call control and signal status, are transported via path 130.

Data paths 140 and 150 can be coupled to a terminal device with two data synchronization paths and can provide a datelox signaling speed of the order of 256 Kbit / s. The video path 160 can be coupled to a teleconferencing terminal. Video signals for teleconferencing and their associated voice signals can be in digital form and compressed into a single data stream, with a total data speed, for example, of the order of 112 up to 384 Kbit / s. Due to the bandwidth required by the video conferencing capability, the access port for video communication, the relay relay switch, is intended for occasional use only and may require one or more signaling channels to be closed during the teleconferencing period.

The rake relay switch 110 may consist of a commercially available raster relay switch unit, such as the 9800, an actuation microcontroller, a ratchet relay switch, manufactured by Teleglobe Inc., Montreal, Canada. The raster relay switch uses the standard trace relay interface network (for example, ANSI, before CCITT) to define the multiplexing of multiple virtual access ports opposed to a single physical communication access port. The standard trace retransmission interface is based on successive transmission and reception through a port

EN 119760 Β1 of access, of individual traces (or packages) of information. In accordance with this standard, the respective trace of the digital data contains addressing and control bits, which are used for directing and detecting the elementary error and the flow control. 3

Fig. 3 illustrates the field format of a raster retransmission frame comprising a n-byte frame including a first raster limiting area (byte 1 = 5

01111110), a 16-bit address field, which includes addresses corresponding to bytes 2 and 3, a data user field corresponding to bytes from 3 to n-3, a 7-bit sequence check (FCS) sequence, occupying the bytes n-2 and n-1 and a terminal area for limiting the crawl (byte n = 01111110). 9

The respective components of the address field of the frame retransmission frame format in fig. 2, in which the bytes 2 and 3 are illustrated in the diagram in fig. 11 4 comprising a first DLCI data path connection identifier, to which bits 3 + 8 of byte 2 are assigned, a bit 2 (not commonly used), an extended address bit 1, a second 13 connection identifier of the the DLCI data path, to which bits 5 + 8 of byte 3 are allocated, a bit 4 conductor (to the destination device) of clear notification of the agglomeration, a bit 3 15 of reverse wave (from the source device) of explicit notification of the agglomeration an error eligibility bit 2 (will be explained) and an extended address bit 1. The bit structure (schematic) for each of the DLCI data path connection identifiers is shown in FIG. 5, while FIG.

presents the bit structure for the trace verification sequence. 19

As previously presented, through the address and control field of the connectivity control program, the relay relay switch 110 can be dynamically configured 21 to provide a multilayered addressing and a selectivity (filtering) device, thus allowing point connection with point of multiple terminal devices, such as a plurality of 23 170-1 voice circuits, ..., 170-N served by the multiplexer unit 135 of the voice circuit to which the path 130 of the voice signal multiplexer is coupled, a connection that will be made in the direction of a single access port. For this purpose, the access codes on the analogue bus or on the side of the voice signal path 130 of the station multiplexer, codes that effectively represent the virtual access ports of the retransmission switch, are translated into retransmission addresses. of the trace (or identifiers of data connection paths 29), which are attached to each data trace, for routing within the network. With this additional information routing, the audio connection is now accessible between any two voice devices (eg buses) in the network.

On the side of its satellite path, the relay switch of track 110, is accessed 33, via a second set of terminal access ports 114, to a plurality of modulation and demodulation circuits contained in the modulator / demodulator unit 120 . For 35 to provide the possibility of closed loop connection together with the network (the four ground stations) of the non-limiting example of fig. 1, described above, the modulator-demodulator unit 37 120 (MODEM) contains a single transmission modulator 210 and a multitude of reception demodulators 220, 230, 240 (three in this example for the four-station network from 39 ground). The respective modulator and demodulator components together with the MODEM 120 unit may contain PSK signaling devices using, for example, type 41 BPSK / QPSK / MSK (data speed dependent) modulation. Thus, the relay relay switch 110 provides dynamic signal routing between one or more terminal devices 43 which are coupled to the access ports 112 and one or more modulators and demodulators belonging to the MODEM 120 unit, which are coupled to the jacks. of access 114. 45

The MODEM 120 unit is coupled with an associated RF transmitter-reception unit 122, which is coupled with a satellite-transmitting / receiving antenna unit 124. Like a 47

EN 119760 Β1 non-limiting example, the respective components of the MODEM 120 unit can interconnect the signals with the transmit-receive unit 122, RF, around the frequency of 70 MHz, while the communication signals with the satellite, sent and received by the transmitting unit 122, can be located within the 11-14.5 GHz bandwidth. RF transmitter unit 122 can operate with signaling formats, either with multiple time division access (TDMA) or single channel (SCPC).

In order to optimize the flow of traffic on the terminal devices (video, voice, data equipment) served, according to the present invention, by an interface based on the retransmission of the rake, the steering control mechanism used by the microcontroller of the raster retransmission switch, further includes a priority step, which provides a variety of step levels [such as, for example, three for the three types of terminal services signaling devices according to this example (video, data, voice)], for controlling the delay of the delay via the relay relay switch 110. in particular, voice traces (accessed via path 140) are assigned the first priority; video conferencing trailers (accessed via path 160) are assigned the next high priority level, and data streams (accessed via path 150) are assigned the lowest priority level. The staggering mechanism is characterized in such a way that during the normal operation, the relay switch of track 110 will not have to offer more traffic than the entire channel can support. Priority grading has no effect on the succession of the transmitted traces. Where the given load increases or the channel error rate exceeds the prescribed limits, the priority scaling mechanism becomes active, to reduce the impact of the load first on the video signaling traffic for teleconferencing and then on the voice signaling traffic.

Because in a closed loop network retransmission network, each ground station is continuously monitored for each receiving channel for the message traces that can be addressed, it is desirable to provide a mechanism for organizing the processing of the signal compression that may be applied differently on the data streams and which was not designed for the terminal device of destination served by this ground station. For this purpose, the parameters of the port retransmit switch access port configuration parameters can be used to define a bit frame (mask), which is used by the microcontroller for filtering and selective removal or to allow partially based traces to pass or totally on the first bit of the retransmission address. This feature of the frame (mask) allows traces received from parallel back channels, which are intended for one or more terminal devices served by this ground station, to be accepted and processed by this raster relay switch. . This preliminary filtration reduces the processing of the load and increases the efficiency of the steering via the ratchet switch.

The address and steering mechanism used by the microcontroller of the retransmission switch contains, together with the retransmission collector, above the quoted indexed bit of acceptability DE (inside the address field of the second byte, shown in fig. 4). , which means for the retransmission network of the trace, whether, during the agglomeration period, this trace can be initially removed, or not, in the attempt to ease the agglomeration condition. In other words, any trace whose indexed bit of acceptability has been set to one, will be removed in an attempt to ease the crowding condition. As a result of the potential agglomeration of the described system, in the priority filtering and phasing mechanisms presented above, a predetermined identifier-de-disconnection of the data path can be used to force the indexed bit of acceptability in the retransmission collector of the data stream.

EN 119760 astr1 of the trace, at a bit for all traces using this special identifier of connection of data path 1. This constraint of the indexed bit of acceptability to one by means of the data connection connection identifier, provides an additional level of trace control, 3 which originates in the terminal devices, which may be unable to introduce themselves, the indexed bit. of acceptability. 5

As it is understood from the aforementioned description, the architecture of the ground station interface based on the retransmission of the creek, according to the present invention, provides a mechanism for successfully achieving the closed loop connection, of a relatively small number of network stations. Advantageously, the fundamental component of the architecture is a trunk retransmission switch, which uses a standard trunk retransmission network interface to perform multiplexing of multiple virtual access ports opposed to a single physical access port. of communications. As a consequence, through the control and address fields of the control program of their connection, the relay relay switch 13 can be dynamically configured to provide a multilayered address and a selectivity device, thus allowing point-to-point connection of multiple devices. terminals, such as a plurality of voice circuits, the connection to be made through a single access port. The access codes on the part of the multiplexing path of the 17 audio (voice) signal of the station are translated into the trace retransmission addresses (data connection identifiers), which are added to each data network for 19 network routing. With this additional arrangement of information guidance, audio (voice) connection is now accessible between any two (voice) audio circuits [eg buses] in 21 networks.

While we have shown and described an embodiment according to the present invention, it is to be understood that the same invention is not limited to this example, but is capable of numerous changes and modifications, within the reach of a person skilled in the art. field and until then we do not want the invention to be limited to the details presented and described below, but we intend, to protect all these obvious changes and changes 27 for a person with ordinary skill in the art.