Communication protocol for satellite data processing

• US 6,522,635 B1
• Filed: 05/28/1996
• Issued: 02/18/2003
• Est. Priority Date: 06/15/1995
• Status: Expired due to Fees

• Current Assignee: ATC Technology Corporation (FedEx Corporation)
• Original Assignee: Mobile Satellite Venture LP
• Inventors: Bedwell, Thomas E.
• Primary Examiner(s): Rao, Seema S.
• Application Number:
  US08/654,453
• Time in Patent Office: 2,457 Days
• Field of Search: 370/313-316, 370/319, 370/321, 370/322, 370/326, 370/328, 370/329, 370/330, 370/336, 370/337, 370/345-350, 370/442, 370/443-445, 370/447, 370/448, 370/437-439, 370/449, 370/428, 370/429, 370/465, 370/473, 370/468, 370/522, 340/825.07, 340/825.08, 455/450-452, 455/509, 455/510, 455/511, 455/512, 455/513, 455/500, 455/501, 455/502, 455/422, 455/426, 455/517, 455/524, 455/67.1
• US Class Current: 370/314
• 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 7/18539 Arrangements for managing radio, resources, i.e. for establishing or releasing a connection
• CPC Class Codes: H04B 7/212 Time-division multiple access [TDMA]

Abstract

A communication system includes a communication switching office having a transceiver for receiving/transmitting a message from/to a data terminal using a communication system, and a management system including a central controller receiving/transmitting the message from/to the communication switching office. The central controller is responsive to the message received from the data terminal, and receives data in the message received from the data terminal. The data terminal transmits to the management system on a message channel. The message channel includes multiple messages from multiple data terminals. The management system receives the multiple messages per message channel or TDM group, and allocates message channel bandwidth for each of the multiple messages to the data terminal responsive to the data terminal call request received on the signalling channel. The management system minimizes the store of the message therein and maximizes the forward of the message, providing the capability to minimize the amount of data that must be stored before transmitting the message to the data terminal, while simultaneously maximizing utilization of communication system resources.

Claims

1. In a mobile satellite system including a satellite communication switching office having a satellite antenna for receiving/transmitting a satellite message via a satellite from/to at least one data terminal of a plurality of data terminals using a mobile communication system, a satellite interface system, a management system including a central controller receiving/transmitting the satellite message from/to the satellite communication switching office, the central controller responsive to the satellite message received from the data terminal via the satellite, and receiving data in the satellite message received from the data terminal, a communication protocol method, comprising the steps of:

(a) transmitting from the management system to the plurality of data terminals on a Time Division Multiplex (TDM) channel, the TDM channel including management system signaling, multiple management system messages, and management system acknowledgments;

(b) transmitting from each data terminal to the management system on a respective signaling channel, the signaling channel including data terminal call requests, data reports, position reports or data terminal acknowledgments, and the management system receiving multiple signaling channels per TDM group or message channel; and

(c) transmitting from the data terminal to the management system on a message channel, the message channel including multiple messages from the plurality of data terminals, the management system receiving the multiple messages per TDMA channel, and allocating message channel bandwidth for each of the multiple messages to the data terminal responsive to the data terminal call request received on one of the multiple signaling channels,

wherein said step (a) of transmitting on the TDM channel includes concurrently transmitting multiple management system messages from the management system to the plurality of data terminals,

wherein the TDM channel includes a plurality of frames, each frame including a plurality of data packets comprising at least a portion of one of the multiple management system messages from the plurality of data terminals, the plurality of data packets being included within the plurality of frames and arranged by sizes of the multiple management system messages and wherein the multiple management system messages including fewer packets have a higher transmission priority than the multiple management messages including more packets.

2. The method according to claim 1, wherein the TDM channel is divided into TDM frames.

3. The method according to claim 2, wherein the TDM channel is divided into the TDM frames and each TDM frame is about 8.64 seconds long and about 639 bytes, including control information.

4. The method according to claim 3,

wherein the TDM channel is divided into the TDM frames and each TDM frame is about 8.64 seconds long and about 639 bytes, including control information, and

wherein the TDM frames provide about 10,000 TDM frames per day, and frame zero occurring at a predetermined time period.

5. The method according to claim 2, wherein each TDM frame is interleaved and encoded using a forward error correction (FEC) encoding so that data within the TDM frame is recoverable even when portions of the TDM frame are lost.

6. The method according to claim 2, wherein each TDM frame is built by the management system out of data packets that are pending transmission.

7. The method according to claim 6, wherein each TDM frame is built by the management system out of data packets that are pending transmission using transmission priority rules.

8. The method according to claim 6, wherein each data packet includes a packet type indicating a packet format, a packet checksum used by the data terminal to detect invalid data packets, and optionally a data terminal address.

9. The method according to claim 1, wherein the data terminal transmits on the signalling channel on a contention basis, with randomizing and retransmission in case of collisions with transmissions of other data terminals.

10. The method according to claim 1, wherein the data terminal transmits on the signalling channel on a contention basis, and the signalling channel is configured to operate at approximately one of 300 bps or 600 bps depending on satellite power availability.

11. The method according to claim 1, wherein the data terminal transmits on the signalling channel using signalling packets, the signalling packets including packet type and checksum information.

12. The method according to claim 1, wherein the data terminal transmits on the messaging channel and the communication switching office allocates the message channel bandwidth, the allocation of the message channel bandwidth effectively providing scheduled TDMA access for the data terminal for the messaging channel.

13. The method according to claim 1, wherein the data terminal transmits on the messaging channel using messaging packets, the messaging packets including packet type and checksum information.

14. The method according to claim 1, wherein a set of the TDM channel and associated signalling and message channels is called a TDM Group, and the management system coordinates access to channels in the TDM group using the TDM.

15. The method according to claim 1, wherein the management system transmits four categories of packets on the TDM channel including:

(1) a bulletin board packet providing overall control information for a TDM Group;

(2) a signalling channel descriptor packet providing reservation of signalling channel slots in the signalling channel and acknowledgement of received data in the signalling channel slots;

(3) a signalling channel packet providing control and acknowledgement signalling; and

(4) a message packet including store and forward message packets as a series of up to 125 byte sized packets.

16. The method according to claim 15, wherein the signalling channel descriptor packet defines a return channel frequency indicating whether the received data was received in the signalling channel slots, and whether the signalling channel slot is reserved.

17. The method according to claim 15, wherein the signalling channel descriptor packet defines a return channel frequency indicating whether the received data was received in the signalling channel slots, and whether the signalling channel slot is reserved.

18. The method according to claim 15, wherein the data terminal sets the signalling channel slot indicating that the satellite message is to be continued across several message packets, and the management system marks the signalling channel slot reserved in the signalling channel descriptor packet so that other data terminals will not transmit in that signalling channel slot.

19. The method according to claim 1, wherein the multiple messages include, when available, a combination of at least one small message, at least one medium message, and at least one long message, the small, medium, and long messages being multiplexed and transmitted to the multiple data terminals.

20. The method according to claim 19, wherein the at least one small message comprises less than about 128 characters, the at least one medium message comprises about between about 128 characters and about 384 characters, and the at least one long message comprises more than about 384 characters.

21. The method according to claim 19, wherein the management system prioritizes the at least one small, medium and long messages in accordance with a predetermined priority.

22. The method according to claim 21, wherein the predetermined priority comprises the at least one small message being of a higher priority than the at least one medium message, and the at least one medium message being of a higher priority than the at least one long message.

23. In a communication system including a communication switching office having a transceiver for receiving/transmitting a message from/to at least one data terminal of a plurality of data terminals using a communication system, a management system including a central controller receiving/transmitting the message from/to the communication switching office, the central controller responsive to the message received from the data terminal, and receiving data in the message received from the data terminal, a communication protocol system, comprising:

said management system transmitting to the plurality of data terminals on a Time Division Multiplex (TDM) channel, the TDM channel including management system signaling, multiple management system messages, and management system acknowledgments, and the plurality of data terminals, responsively connected to said management system, each data terminal transmitting to the management system on a respective signaling channel, the respective signaling channel including data terminal call requests, data reports, position reports or data terminal acknowledgments, and the management system receiving multiple signaling channels per TDM group or messaging channel, and said data terminal transmitting to the management system on a message channel, the message channel including multiple messages from multiple data terminals, the management system receiving the multiple messages per TDMA channel, and allocating message channel bandwidth for each of the multiple messages to the data terminal responsive to the data terminal call request received on one of the multiple signaling channels,

wherein the TDM channel includes the multiple management system messages concurrently transmitted from the management system to the plurality of data terminals,

wherein the TDM channel includes a plurality of frames, each frame including a plurality of data packets comprising at least a portion of one of the multiple management system messages from multiple data terminals, the plurality of data packets being included within a frame transmission by a FIFO-free message transmission prioritization for a message queue.

24. The communication protocol system according to claim 23, wherein the TDM channel is divided into TDM frames.

25. The communication protocol system according to claim 24, wherein the TDM channel is divided into the TDM frames and each TDM frame is about 8.64 seconds long and about 639 bytes, including control information.

26. The communication protocol system according to claim 25,

wherein the TDM channel is divided into the TDM frames and each TDM frame is about 8.64 seconds long and about 639 bytes, including control information, and

wherein the TDM frames provide about 10,000 TDM frames per day, and frame zero occurring at a predetermined time period.

27. The communication protocol system according to claim 24, wherein each TDM frame is interleaved and encoded using a forward error correction (FEC) encoding so that data within the TDM frame is recoverable even when portions of the TDM frame are lost.

28. The communication protocol system according to claim 24, wherein each TDM frame is built by the management system out of data packets that are pending transmission.

29. The communication protocol system according to claim 28, wherein each TDM frame is built by the management system out of data packets that are pending transmission using transmission priority rules.

30. The communication protocol system according to claim 28, wherein each data packet includes a packet type indicating a packet format, a packet checksum used by the data terminal to detect invalid data packets, and optionally a data terminal address.

31. The communication protocol system according to claim 23, wherein the data terminal transmits on the signalling channel on a contention basis, with randomizing and retransmission in case of collisions with transmissions of other data terminals.

32. The communication protocol system according to claim 23, wherein the data terminal transmits on the signalling channel on a contention basis, and the signalling channel is configured to operate at approximately one of 300 bps or 600 bps depending on satellite power availability.

33. The communication protocol system according to claim 23, wherein the data terminal transmits on the signalling channel using signalling packets, the signalling packets including packet type and checksum information.

34. The communication protocol system according to claim 23, wherein the data terminal transmits on the messaging channel and the communication switching office allocates the message channel bandwidth, the allocation of the message channel bandwidth effectively providing scheduled TDMA access for the data terminal for the messaging channel.

35. The communication protocol system according to claim 23, wherein the data terminal transmits on the messaging channel using messaging packets, the messaging packets including packet type and checksum information.

36. The communication protocol system according to claim 23, wherein a set of the TDM channel and associated signalling and message channels is called a TDM Group, and the management system coordinates access to channels in the TDM group using the TDM.

37. The communication protocol system according to claim 23, wherein the management system transmits four categories of packets on the TDM channel including:

(1) a bulletin board packet providing overall control information for a TDM Group;

(2) a signalling channel descriptor packet providing reservation of signalling channel slots in the signalling channel and acknowledgement of received data in the signalling channel slots;

(3) a signalling channel packet providing control and acknowledgement signalling; and

(4) a message packet including store and forward message packets as a series of up to 125 byte sized packets.

38. The communication protocol system according to claim 37, wherein the signalling channel descriptor packet defines a return channel frequency indicating whether the received data was received in the signalling channel slots, and whether the signalling channel slot is reserved.

39. The communication protocol system according to claim 37, wherein the signalling channel descriptor packet defines a return channel frequency indicating whether the received data was received in the signalling channel slots, and whether the signalling channel slot is reserved.

40. The communication protocol system according to claim 37, wherein the data terminal sets the signalling channel slot indicating that the satellite message is to be continued across several message packets, and the management system marks the signalling channel slot reserved in the signalling channel descriptor packet so that other data terminals will not transmit in that signalling channel slot.

41. The communication protocol system according to claim 23, wherein the multiple messages includes the combination of at least one small message, at least one medium message and at least one long message, when the small, medium and long messages are transmitted when available to the multiple data terminals.

42. The communication protocol system according to claim 41, wherein the at least one small message comprises less than about 128 characters, the at least one medium message comprises about between about 128 characters and about 384 characters, and the at least one long message comprises more than about 384 characters.

43. The communication protocol system according to claim 41, wherein the management system prioritizes the at least one small, medium and long messages in accordance with a predetermined priority.

44. The communication protocol system according to claim 43, wherein the predetermined priority comprises the at least one small message being of a higher priority than the at least one medium message, and the at least one medium message being of a higher priority than the at least one long message.

45. A communication protocol system for transferring data between a management system and a plurality of data terminals via a satellite, said system comprising:

a management system; and

a plurality of data terminals;

said management system and said plurality of data terminals including a transmission channel having a plurality of multiplexed outbound messages from the management system to the plurality of data terminals, the plurality of multiplexed outbound messages being concurrently transmitted;

said management system and said plurality of data terminals including a signaling channel having a data terminal call request from a requesting data terminal of said plurality of data terminals to the management system to receive message channel bandwidth allocation therefrom; and

said management system and said plurality of data terminals including a message channel having an inbound message from a calling data terminal of said plurality of data terminals to said management system,

wherein the transmission channel includes a plurality of frames, each frame including a plurality of data packets comprising at least a portion of one of the plurality of multiplexed outbound messages, the plurality of data packets being included within a frame transmission, each packet of said plurality of data packets including a packet size at least as large as a predetermined message size while maximizing simultaneous transmission of the plurality of multiplexed outbound messages, and

wherein said transmission channel includes a plurality of frames, each frame of said plurality of frames including a plurality of packets, each outbound message of the plurality of outbound messages being divided into at least one packet of said plurality of packets, said plurality of packets being time division multiplexed within a frame transmission so that respective packets of at least two outbound messages are substantially simultaneously transmitted within the frame transmission.

46. The system according to claim 45, wherein each packet of said plurality of packets has a size of 64 characters.

47. The system according to claim 45, wherein said transmission-channel includes an announcement of receipt at the management system of a future outbound message to at least one receiving data terminal of the plurality of data terminals.

48. The system according to claim 46, wherein said plurality of packets are time division multiplexed within the frame transmission by size so that said outbound messages divided into fewer packets are given a higher transmission priority than said outbound messages divided into more packets.

49. The system according to claim 48, wherein said transmission channel additionally includes a poll message for at least one data terminal of said plurality of data terminals from another data terminal of said plurality of data terminals, the poll message having a higher transmission priority than an outbound message of a comparable size of the plurality of outbound messages.

50. The system according to claim 45, wherein each data terminal of said plurality of data terminals includes a two minute call completion timer.

51. The communication protocol system of claim 45 wherein the predetermined message size is approximately equal to an average size of the plurality of multiplexed outbound messages.

52. The communication protocol system of claim 51 wherein the average size is in a range of 50-60 characters.

53. The communication protocol system of claim 45 wherein the plurality of multiplexed outbound messages are simultaneously transmitted.

54. A communication protocol method for transferring data between a management system and a plurality of data terminals via a satellite, said protocol method comprising the steps of:

multiplexing a plurality of outbound messages at the management system;

transmitting the multiplexed plurality of outbound messages concurrently on a transmission channel from the management system to the plurality of data terminals;

transmitting a data terminal call request from a requesting data terminal of the plurality of data terminals on a signaling channel to the management system to receive message channel bandwidth allocation therefrom; and

transmitting an inbound message from a calling data terminal of the plurality of data terminals on a message channel to the management system,

wherein the transmission channel includes a plurality of frames, each frame including a plurality of data packets comprising at least a portion of one of the plurality of outbound messages, the plurality of data packets being included within the plurality of frames and arranged by sizes of the multiple management system messages and wherein the plurality of outbound messages including fewer packets have a higher transmission priority than the plurality of outbound messages including more packets.

55. The method according to claim 54,

wherein said multiplexing step includes dividing each outbound message of a plurality of outbound messages to the plurality of data terminals into at least one packet of a plurality of packets at the management system, and time division multiplexing, by utilizing a priority scheme, the plurality of packets in at least one frame of a plurality of frames at the management system so as to maximize a number of outbound messages that can be transmitted simultaneously in the at least one frame; and

wherein said transmitting step includes transmitting the at least one frame via the transmission channel from the management system to the plurality of data terminals.

56. The method according to claim 55, further comprising the steps of:

including in the at least one frame an announcement of receipt at the management system of a future outbound message to at least one of the plurality of data terminals, prior to transmitting a first packet of the future outbound message in a subsequent frame.

57. The communication protocol method according to claim 55, further comprising the step of:

analyzing an outbound message size of the each of the outbound messages at the management system, wherein the priority scheme includes prioritizing the plurality of packets based on a respective outbound message size of the each of the outbound messages so that a packet of the plurality of packets associated with a larger outbound message receives a lower priority than a packet of the plurality of packets associated a smaller outbound message.

58. The method according to claim 55, wherein each packet of the plurality of packets has a size of 64 characters.

59. The method according to claim 54, wherein each of the plurality of data terminals includes a two minute call completion timer.

60. The communication protocol system of claim 54 wherein the plurality of multiplexed outbound messages are simultaneously transmitted.

61. In a mobile satellite system including a satellite communication switching office for receiving/transmitting a satellite message via a satellite from/to at least one data terminal of a plurality of data terminals, a central controller receiving/transmitting the satellite message from/to the satellite communication switching office, the central controller responsive to the satellite message received from the data terminal via the satellite, and receiving data in the satellite message received from the data terminal, a communication protocol method, comprising the step of transmitting a plurality of messages from a management system to the plurality of data terminals respectively at least one of simultaneously and concurrently on a same communication channel in accordance with predetermined criteria, the plurality of data packets being included within a frame transmission, each packet of the plurality of data packets including a packet size at least as large as a predetermined message size while maximizing simultaneous transmission of the plurality of messages.

62. The method according to claim 61, wherein said transmitting step further comprises the step of transmitting the plurality of messages from the management system to the plurality of data terminals respectively at least one of simultaneously and concurrently on the second channel in accordance with the predetermined criteria including message size of each of the plurality of messages.

63. The communication protocol system of claim 61 wherein the predetermined message size is approximately equal to an average size of the plurality of multiplexed outbound messages.

64. The communication protocol system of claim 63 wherein the average size is in a range of 50-60 characters.

65. A communication protocol system for transferring data via a satellite, comprising

a management system;

a plurality of data terminals communicating with said management system via the satellite,

said management system and said plurality of data terminals communicating over at least one TDM channel, and

a plurality of outbound communications being transmitted from said management system to said plurality of data terminals in accordance with a communications protocol, each outbound communication of said plurality of outbound communications including a plurality of packets, each packet of said plurality of packets being transmitted on one TDM channel of said at least one TDM channel,

a network coordination station communicating with said plurality of data terminals, and

wherein said system is configured to be free of the network coordination station communicating with said plurality of data terminals when said plurality of data terminals are not engaged in message transfer.

66. The system according to claim 65, wherein each TDM channel of said at least one TDM channel is free of a demand-assigned mode.

67. A communication protocol system for transferring data via a satellite, comprising

a management system;

a plurality of data terminals communicating with said management system via the satellite,

said management system and said plurality of data terminals communicating over at least one TDM channel, and

a plurality of outbound communications being transmitted from said management system to said plurality of data terminals in accordance with a communications protocol, each outbound communication of said plurality of outbound communications including a plurality of packets, each packet of said plurality of packets being transmitted on one TDM channel of said at least one TDM channel,

wherein said management system includes a plurality of data mailboxes, said management system forwarding at least one of a data report and a message addressed to said plurality of data mailboxes to a terrestrial host processor without storing said at least one of a data report and a message in said plurality of data mailboxes, unless forwarding fails.

68. The system according to claim 67, wherein said at least one TDM channel includes a load-balanced plurality of TDM channels per spot beam.

69. The system according to claim 67, wherein said plurality of data terminals scan said at least one TDM channel when a signal therefrom is lost.

70. The system according to claim 69, wherein the signal is lost during roaming between spot beams.

71. The system according to claim 67, wherein said at least one TDM channel includes a plurality of frames, each frame including a plurality of signaling bursts per data terminal.

72. The system according to claim 67, wherein said at least one TDM channel includes a plurality of frames, each frame including a plurality of signaling bursts per said plurality of data terminals.

73. The system according to claim 67, wherein said at least one TDM channel including an immediate acknowledgment with retry mechanism.

74. The system according to claim 67, wherein said at least one TDM channel includes a plurality of automated group call acknowledgments.

75. In a mobile satellite system including a satellite communication switching office for receiving/transmitting a satellite message via a satellite from/to at least one data terminal of a plurality of data terminals, a central controller receiving/transmitting the satellite message from/to the satellite communication switching office, the central controller responsive to the satellite message received from the data terminal via the satellite, and receiving data in the satellite message received from the data terminal, a communication protocol method, comprising the steps of:

(d) transmitting at least one data terminal message from a plurality of data terminals to a management system on at least one first channel, the at least one data terminal message including at least one of data terminal call requests, data reports, position reports, data messages and data terminal acknowledgments;

(e) receiving by the management system the at least one data terminal message from the plurality of data terminals; and

(f) transmitting plurality of management system messages from the management system to the plurality of data terminals respectively at least one of simultaneously and concurrently on a second channel in accordance with predetermined criteria,

wherein the at least one first channel includes a plurality of frames, each frame including a plurality of data packets comprising at least a portion of one of the multiple management system messages, the plurality of data packets being included within a frame transmission a FIFO-free message transmission prioritization for a message queue.

76. The method according to claim 75, wherein said transmitting step (c) further comprises the step of transmitting the plurality of management system messages from the management system to the plurality of data terminals respectively at least one of simultaneously and concurrently on the second channel in accordance with the predetermined criteria including message size of each of the plurality of management system messages.

77. A communication protocol system for transferring data between a management system and a plurality of data terminals via a satellite, said communication protocol system comprising:

a management system; and

a plurality of data terminals,

said management system and said plurality of data terminals communicating over a transmission channel, a plurality of outbound messages being transmitted from the management system to said plurality of data terminals in accordance with a communication protocol,

said communication protocol system defining a plurality of frames, each frame including a plurality of data packets comprising at least a portion of one of the plurality of outbound messages, wherein at least one of

(a) said plurality of data packets is included within a frame transmission by message size,

(b) said plurality of data packets is included within a frame transmission by a FIFO-free message transmission prioritization for a message queue, and

(c) said plurality of data packets is included within a frame transmission, each packet of said plurality of data packets including a packet size at least as large as a predetermined message size while maximizing simultaneous transmission of the plurality of outbound messages.

78. The communication protocol system of claim 77 wherein the predetermined message size is approximately equal to an average size of the plurality of multiplexed outbound messages.

79. The communication protocol system of claim 78 wherein the average size is in a range of 50-60 characters.

80. A communication protocol system for transferring data via a satellite, comprising

means for managing a system;

a plurality of data terminal means for communicating with said management means via the satellite,

said management means and said plurality of data terminal means communicating over at least one TDM channel, and

a plurality of outbound communications being transmitted from said management means to said plurality of data terminal means in accordance with a communications protocol, each outbound communication of said plurality of outbound communications including a plurality of packets, each packet of said plurality of packets being transmitted on one TDM channel of said at least one TDM channel,

means for communicating and coordinating with said plurality of data terminals, and

wherein said management means is configured to be free of the means for communicating and coordinating with said plurality of data terminals when said plurality of data terminal means are not engaged in message transfer.