System for satellite digital communications with onboard processing adaptive to the attenuation traffic and radio interface conditions for point to point communication and meshed grids

• US 20090303916A1
• Filed: 06/28/2006
• Published: 12/10/2009
• Est. Priority Date: 06/28/2005
• Status: Active Grant

• Current Assignee: Finmeccanica SPA
• Original Assignee: Finmeccanica SPA
• Inventors: Winkler, Roberto, Mura, Rodolfo, Losquadro, Giacinto
• Granted Patent: US 7,864,723 B2
• Time in Patent Office: Days
• US Class Current: 370/315
• CPC Class Codes: H04B 7/18515 Transmission equipment in satellites or space-based relays

Abstract

The present invention provides apparatus for processing and regenerating the signals of telecommunication satellites, for meshed communications on multi-beam coverage between standard DVB-RCS and DVB-S2 user terminals and apparatus for filtering and routing the signals transferred between ground terminals.

Claims

1. An apparatus for processing and regenerating the signals of telecommunication satellites, for meshed communications on multi-beam coverage between standard DVB-RCS and DVB-S2 user terminals, said apparatus consisting of the following parts:

a filtering device bench (Fil);

a trailing conversion device bench (ConvD);

an analogue-digital conversion device bench (CAD);

a channel demultiplexing device bench (DemC);

a space and frequency switching device bench (ComSF);

a signal processor controller (CPS);

a demodulation and turbo decoding device bench (DemDec);

a PID acknowledgement device bench (RPID);

a modulation and formatting device bench (ModFor);

a circular signalling bus (BCS);

an digital-analogue conversion device bench (CAD1);

a leading conversion device bench (ConvS)

characterised in that;

f. a number NC of radiofrequency channels (C1, C2, C3, . . . ) carrying the digital signals (SD1, SD2, SD3, . . . ) generated by the ground terminals enter into said filtering device bench (Fil) and therein said channels are separated in band to be then converted by the trailing conversion device bench (ConvD) to the operating frequency of the channel demultiplexing device bench (DemC) that receives said channels C1, C2, C3, . . . in digital format (CD1, CD2, CD3, . . . ) by the conversion carried out by the analogue-digital conversion device bench (CAD);

said channels are then processed by the channel demultiplexing device bench (DemC) that produces the desired number Nsc of sub-channels (SC1, SC2, SC3, . . . ), each containing the modulated and encoded symbols that represent the information contents at the intermediate frequency of said digital signals (SD1, SD2, SD3, . . . );

said desired number Nsc of said incoming sub-channels (SCE1, SCE2, SCE3, . . . ) is determined by the bandwidth of said radiofrequency channels (C1, C2, C3, . . . ) and by the bandwidth of said sub-channels (SCE1, SCE2, SCE3, . . . );

g. said incoming sub-channels (SCE1, SCE2, SCE3, . . . ) are switched in space and frequency by said space and frequency switching device bench (ComSF), which processes the symbols belonging to said incoming sub-channels for generating as many output sub-channels (SCU1, SCU2, SCU3, . . . ) to the output lines of said ComSF, thus originating a re-distribution in the space and frequency of said digital signals (SD1, SD2, SD3, . . . );

h. said output sub-channels (SCU1, SCU2, SCU3, . . . ) are provided in input to the demodulation and turbo decoding device bench (DemDec) that processes said sub-channels applying the current demodulation profile (PADM, for example 8PSK) and the current turbo decoding profile (PADT, for example FEC 3/4) and produces the digital flows in base band (FDB1, FDB2, FDB3, . . . );

said PADM and PADT respectively belong to the set of demodulation profiles (PDM1, PDM2, PDM3 . . . ) and of turbo decoding profiles (PTD1, PTD2, PTD3, . . . ) obtained by said DemDec;

said demodulation profiles (PDM1, PDM2, PDM3 . . . ) and said turbo decoding profiles (PTD1, PTD2, PTD3, . . . ) comply with the schemes specified by the standard DVB-RCS and form a suitable subset thereof;

said PADM and PADT are defined on the basis of the strength objectives to the attenuations on the leading channel and of usage efficiency of the transmission band by said digital signals (SD1, SD2, SD3, . . . );

said PADM and PADT are actuated by said DemDec after a command sent by the signal processor controller (CPS);

i. said digital flows in base band (FDB1, FDB2, FDB3, . . . ) are provided in input to the modulation and formatting device bench (ModFor);

said ModFor generates regenerated digital flows (FDR, 1, FDR2, FDR3, . . . ) applying the current modulation profile (PAM, for example 8PSK) and the current turbo encoding profile (PAC, for example LDPC with FEC 3/4);

said PAM and PAC respectively belong to the set of modulation profiles (PM1, PM2, PM3 . . . ) and of encoding profiles (PC1, PC2, PC3, . . . ) carried out by said ModFor;

said modulation profiles (PM1, PM2, PM3 . . . ) and encoding profiles (PC1, PC2, PC3, . . . ) comply with the schemes specified by the standard DVB-RCS and form a suitable subset thereof;

said PAM and PAC are defined on the basis of the strength objectives to the attenuations on the trailing channel and of usage efficiency of the transmission band by said digital signals (SD1, SD2, SD3, . . . );

said PAM and PAC are actuated by said ModFor after a command sent by said CPS;

the number of said regenerated digital flows (FDR, 1, FDR2, FDR3, . . . ) is equal to the number NC of said radiofrequency channels (C1, C2, C3, . . . );

j. said regenerated digital flows (FDR, 1, FDR2, FDR3, . . . ) cross the digital-analogue conversion device bench (CDA1) and the leading conversion device bench (ConvS) to be then provided to the subsequent amplification sections onboard of the satellite before they are radio-transmitted on the trailing channel.

2. An apparatus for regenerating the signals onboard of telecommunication satellites with adaptivity of the modulation and encoding for increasing the protection of the information in conditions of poor availability of the leading (from ground terminal to satellite) and/or trailing channel (from satellite to ground terminal), said apparatus being based on the apparatus according to claim 1

characterised by the following sequence of operations:

g. maintaining said current modulation profile (PAM) and said current turbo encoding profile (PAC) by said DemDec, in the absence of variations over the threshold of the signal to noise ratio reported by said DemDec for a time longer than the minimum deviation time (TMD);

h. said DemDec carries out the signal measurements on the time slots of the leading channels and counts the packets discarded during the decoding following an excessive number of unrecoverable errors;

the measured values are transmitted to the ground as ACM telemetries, in the format MPEG2 Private Section and are encapsulated into packets MPEG2-TS

i. the ground control station (SCT) processes said ACM telemetries and if necessary, subsequent to changed conditions on the channel, said SCT determines the target modulation profile (POM) and the target turbo encoding profile (POC) to be actuated on the leading channel for attenuating the effects of the changed radio-propagation conditions;

said SCT checks the availability of a sufficient number of time-slots available for said POM and POC on the same carrier, or checks the availability of said time-slots on other carriers on the leading channel (optionally also through reorganisation of the format into two or more leading carriers) in MF-TDMA standard DVB-RCS format;

j. if said time-slots are available, said SCT emits the updated standard DVB-RCS SCT, TCT and FCT TBTP tables to assign to the ground terminal the necessary slots on the carrier that conveys said time-slots;

if said time slots are not available, the radio-connection may undergo quality or transmission efficiency degradations;

k. said SCT sends the remote control signal to said CPS to update the configuration of said DemDec according to said POM and POC and according to said reorganisation of the format of the leading carriers;

l. said CPS sends the signal confirming the correct reconfiguration of said DemDec to said SCT, with signal in transport format MPEG2 private section encapsulated in packets MPEG-TS.

3. An apparatus for processing the signals onboard of telecommunication satellites for regenerated meshed communications on multi-beam coverage, by the combined selection and actuation of translucent onboard processing mode and regenerative onboard processing mode of satellite channels, according to claim 1, further comprising the following parts:

a channel re-multiplexing device bench (MulC);

an digital-analogue conversion device bench (CAD2);

a filtering and trailing channel selector bench (SCDF)

characterised in that;

f. a number NC of radiofrequency channels (C1, C2, C3, . . . ) carrying the digital signals (SD1, SD2, SD3, . . . ) generated by the ground terminals and by the ground stations enter into said filtering device bench (Fil) and therein said channels are separated in band to be then converted as per claim 1 for producing the desired number Nsc of sub-channels (SC1, SC2, SC3, . . . ), each containing the modulated and encoded symbols that represent the information contents at the intermediate frequency of said digital signals (SD1, SD2, SD3, . . . ). Said desired number Nsc of said incoming sub-channels (SCE1, SCE2, SCE3, . . . ) is determined as per claim 1;

g. said incoming sub-channels (SCE1, SCE2, SCE3, . . . ) are switched in space and frequency by said space and frequency switching device bench (ComSF), obtaining the output sub-channels (SCU1, SCU2, SCU3, . . . ) as per claim 1;

h. said output sub-channels (SCU1, SCU2, SCU3, . . . ) can be provided in input alternately to said DemDec for regeneration or to the channel re-multiplexing device bench (MulC) for frequency re-combination, so as to actuate the routing configuration required by said CPS on the basis of the distribution of said incoming sub-channels (SCE1, SCE2, SCE3, . . . ) between the sub-channels to be regenerated (SCR1, SCR2, SCR3, . . . ) since associated to user terminals operating according to specific DVB-RCS and DVB-S2 and the sub-channels to be transmitted (SCT1, SCT2, SCT3, . . . ) since associated to the ground terminals not operating according to specific DVB-RCS and DVB-S2

i. said output sub-channels (SCU1, SCU2, SCU3, . . . ) corresponding to said sub-channels to be regenerated (SCR1, SCR2, SCR3, . . . ) are provided in input to said DemDec and then processed as per claim 1;

j. said output channels (SCU1, SCU2, SCU3, . . . ) corresponding to said sub-channels to be transmitted (SCT1, SCT2, SCT3, . . . ) are provided in input to said MulC;

said MulC forms the processed digital flows (FDP, 1, FDP2, FDP3, . . . ) by assembling the corresponding symbols;

the number of said processed digital flows (FDP, 1, FDP2, FDP3, . . . ) is equal to number NC of said radiofrequency channels (C1, C2, C3, . . . );

said processed digital flows (FDP, 1, FDP2, FDP3, . . . ) are thus equal in number and in the modulation and encoding formats of said radiofrequency channels (C1, C2, C3, . . . ).

4. An apparatus for filtering and routing the signals transferred between ground terminals according to claim 1, characterised by the following sequence of operations:

h. configuration by said CPS, of the PID acknowledgement device bench (RPID) with the set of the PID field values (IVPID) that said RPID must acknowledge and filter in the header of packets MPEG 2;

the cardinality of said IVPID being defined based on schemes that are not a part of this claim and said IVPID being reconfigurable based on schemes that are not a part of this claim;

i. filtering by said RPID of the 13 bits of the PID field from the header of packet MPEG-2 provided to the output of said DemDec, for each packet in output from said DemDec;

j. calculation of the current value of said PID field (VAPID) and check of the matching between said VAPID and the values in said IVPID;

k. in case of no matching between said VAPID and the values in said IVPID, said packet MPEG results as not carrying signalling information and is sent without any additional operation to said ModFor;

l. in case of matching between said VAPID and the PID value corresponding to the signal exchanged in DULM mode between the user terminals and to the ground control stations, said packet MPEG must pass on said circular signalling bus (BCS) to be processed by the suitable section of said ModFor,

m. in case of matching between said VAPID and the PID value corresponding to the remote control signal from the ground control stations to said CPS, said packet MPEG must pass on said circular signalling bus (BCS) to be processed by the signal processor that requests the actuation of the onboard processor reconfiguration remote control actuation to said DemDec;

n. in case of matching between said VAPID and the PID value corresponding to the signal emitted by the ground control stations to the user terminals, said packet MPEG must pass on said circular signalling bus (BCS) to be processed by the suitable section of said ModFor.