Digital radio communication apparatus and method for communication in a satellite-supported VSAT network

• US 6,256,496 B1
• Filed: 03/10/1997
• Issued: 07/03/2001
• Est. Priority Date: 03/09/1996
• Status: Expired due to Fees

• Current Assignee: Deutsche Telekom AG
• Original Assignee: Deutsche Telekom AG
• Inventors: Ortgies, Gerd, von Hugo, Dirk, Dintelmann, Friedrich, Ruecker, Friedrich
• Primary Examiner(s): MAUNG, NAY AUNG
• Application Number:
  US08/814,142
• Time in Patent Office: 1,576 Days
• Field of Search: 455/12.1, 455/13.1, 455/13.4, 455/67.1, 455/67.4, 455/101, 455/423, 455/427, 455/430, 455/507, 455/509, 348/14, 348/15, 348/16, 701/13
• US Class Current: 455/427
• CPC Class Codes: H04B 7/18528 Satellite systems for providing two-way communications service to a network of fixed stations, i.e. fixed satellite service or very small aperture terminal [VSAT] system
• CPC Class Codes: H04B 7/18584 Arrangements for data networking, i.e. for data packet routing, for congestion control data switching networks H04L12/00

Abstract

An improved digital radio communication apparatus and method for communicating in a satellite-supported VSAT network consisting of a plurality of VSAT member stations and at least one central station or hub. Both the apparatus and method concern VSAT systems performing voice, video and data communication in meshed networks comprising at least one central station or hub and VSAT stations via a satellite. The hub sends its information via at least one of its earth stations to the VSAT stations and receives at other frequencies the messages sent by the VSAT stations. Transmission frequencies and allowable overall bit rates are established by the hub as a function of the propagation conditions prevailing on the individual satellite paths. Member traffic is classified as time-critical traffic (ZKV) or non-time-critical traffic (ZUV). A hub comprises two or more earth stations or diversity stations linked by a terrestrial line with traffic always conducted via the earth station or diversity station suffering the least propagation effects and/or system component failures. The central station or hub assigns the individual members, upon request, a secure frequency, at which higher transmission quality is achieved due to lower intermodulation interference, with this assignment possibly referring to a narrow-band transmission channel through which direct telephone traffic can be conducted between two members, avoiding double hop.

Claims

1. A method for improving digital radio communication in a satellite-supported VSAT network having a plurality of VSAT member stations with at least one central station for voice, video, and data communication, wherein individual members and user groups can request telecommunication services which comprise signal traffic over the VSAT network, the method comprising the steps of:

classifying the signal traffic as time-critical traffic (ZKV) and non-time-critical traffic (ZV); and

determining, in the central station, at least one transmission parameter of at least one satellite link of the VSAT network as a function of at least one propagation condition on at least one communication path of the signal traffic.

2. The method according to claim 1, further comprising the step of:

conducting the signal traffic via at least one earth-based sub-station of the central station that is least affected by the at least one propagation condition and/or failure of at least one system component in the central station.

3. The method according to claim 1, further comprising the step of:

assigning to the signal traffic a secure frequency at which a higher transmission quality is achieved due to lower intermodulation interference.

4. The method according to claim 3, wherein the secure frequency is a narrow-band transmission channel and through which the signal traffic takes place without a double hop.

5. The method according to claim 1, wherein the determining step includes observing a certain transmission quality for the time-critical traffic (ZKV), the method further comprising the step of:

transmitting the non-time-critical traffic (ZUV), in addition to the time-critical traffic (ZKV), when the certain transmission quality is determined to be high enough.

6. The method according to claim 5, wherein the certain transmission quality is determined as a function of a bit error rate, and that the transmitting step occurs when the bit error rate is determined to be low enough.

7. The method according to claim 5, wherein the transmitting step includes transmitting both the time-critical traffic (ZKV) and the non-time-critical traffic (ZUV) through a non-active earth-based sub-station, the method further comprising the step of:

when the certain transmission quality falls below a predefined threshold, implementing a plurality of transmission ensuring measures in order to maintain the time-critical traffic (ZKV) even with a decreased transmission quality.

8. The method according to claim 7, wherein the plurality of transmission ensuring measures includes a Fade Counter Measure.

9. The method according to claim 7, wherein the decreased transmission quality is achieved by a reduced effective data rate.

10. The method according to claim 1, wherein for at least one point-to-multipoint data transmission, the method further comprising the steps of:

combining a plurality of data blocks received by at least one VSAT station with error into a single correction block; and

extracting, by at least one VSAT station, a required information from the single correction block and a plurality of previously received correct data blocks.

11. The method according to claim 10, wherein the data transmission takes place between at least two VSAT stations via the central station, the method further comprising the steps of:

demodulating the required information at the central station;

forwarding, to a receiving VSAT station, only the plurality of correct data blocks; and

reporting, to a transmitting VSAT station, when at least one data block contains errors, wherein in a case of a strong attenuation event on the transmission path between the central station and the receiving VSAT station, the information is temporarily stored at the central station and is forwarded at a later, more favorable time.

12. The method according to claim 1, further comprising the steps of:

determining, at the central station, the at least one propagation condition from a reception of at least one self-emitted signal and from a comparison of a traffic signal level received from at least one VSAT station with a traffic signal level transmitted by at least one VSAT station; and

distributing, to the plurality of member VSAT stations, the at least one determined propagation condition and the at least one transmission parameter as a function of the propagation condition.

13. An apparatus for improved digital radio communications in a satellite-supported VSAT network comprising:

at least one central station having a central station computer;

a plurality of member VSAT stations;

a satellite,

at least one outroute signal, emitted by the central station, containing a plurality of system information, a plurality of data and audiovisual information, and a plurality of forwarded information from at least one VSAT stations, wherein the plurality of system information contains at least one transmission parameter for sending a signal traffic to the plurality of member VSAT stations; and

at least one inroute signal, emitted by at least one VSAT station, containing a plurality of data and audiovisual information, a plurality of information for the plurality of member VSAT stations, and direct telephony between the VSAT stations.

wherein the central station further comprises a plurality of earth-based sub-stations arranged clearly separated from one another, each of the earth-based sub-stations having an antenna and transmission equipment in a radio frequency range for communicating with the satellite, and a plurality of terrestrial line links between each one of the earth-based sub-stations and between each one of the earth-based sub-stations and the central station computer.

14. An apparatus for improved digital radio communications in a satellite-supported VSAT network, comprising:

at least one central station having a central station computer;

a plurality of member VSAT stations; and

a satellite,

wherein the central station further comprises a plurality of earth-based sub-stations arranged clearly separated from one another each of the earth-based sub-stations having an antenna and transmission equipment in a radio frequency range for communicating with the satellite, and a plurality of terrestrial line links between each one of the earth-based sub-stations and between each one of the earth-based sub-stations and the central station computer, and

wherein the at least one transmission parameter is stored in a memory or is determined by a control program implemented on the central station computer using an adjusted dynamic process which takes into account at least one condition of the VSAT network configuration.

15. An apparatus for improved digital radio communications in a satellite-supported VSAT network comprising:

at least one central station having a central station computer;

a plurality of member VSAT stations; and

a satellite,

wherein the central station further comprises a plurality of earth-based sub-stations arranged clearly separated from one another, each of the earth-based sub-stations having an antenna and transmission equipment in a radio frequency range for communicating with the satellite, and a plurality of terrestrial line links between each one of the earth-based sub-stations and between each one of the earth-based sub-stations and the central station computer, and

wherein signal traffic within the VSAT network is classified as time-critical traffic (ZKV) and non-time-critical traffic (ZUV), and the central station determines at least one transmission parameter of at least one satellite link of the VSAT network as a function of at least one propagation condition on at least one communication path of the signal traffic.

16. An apparatus for improved digital radio communications in a satellite-supported VSAT network, comprising:

at least one central station having a central station computer;

a plurality of member VSAT stations; and

a satellite,

wherein the central station further comprises a plurality of earth-based sub-stations arranged clearly separated from one another, each of the earth-based sub-stations having an antenna and transmission equipment in a radio frequency range for communicating with the satellite, and a plurality of terrestrial line links between each one of the earth-based sub-stations and between each one of the earth-based sub-stations and the central station computer, and

wherein if one of the plurality of earth-based sub-stations experiences a breakdown, a communication with the central station occurs via another one of the plurality of earth-based sub-stations.