Method and apparatus for transmitting data

• US 7,043,196 B1
• Filed: 07/31/1997
• Issued: 05/09/2006
• Est. Priority Date: 07/31/1996
• Status: Expired due to Fees

• Current Assignee: Inmarsat Global Limited (Inmarsat PLC)
• Original Assignee: Inmarsat Incorporated (Inmarsat PLC)
• Inventors: Randall, David, McTiffin, Michael John, Kawai, Nobuyuki, Wong, Hok Shuen
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US08/904,312
• Time in Patent Office: 3,204 Days
• Field of Search: 455/12.1, 455/517, 455/435, 455/432, 370/394, 370/428, 370/473, 370/474, 370/475, 714/748, 714/749, 714/747, 714/746, 714/751, 714/456.1
• US Class Current: 455/12.1
• CPC Class Codes: H04B 7/18523 Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service arrangements specially adapted for satellite broadcast receiving H04H40/90; picture transmission via satellite H04N1/00103; television transmission via satellite H04N7/20
• CPC Class Codes: H04B 7/18582 Arrangements for data linking, i.e. for data framing, for error recovery, for multiple access
• CPC Class Codes: H04L 1/1685 the supervisory signal being transmitted in response to a specific request, e.g. to a polling signal
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/187 Details of sliding window management
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint

Abstract

Data relating to the status of users 12 in a mobile communications system is broadcast via satellite 8 from a network register 4 to local registers 10 in an HDLC format. Each of the local registers 10 requests retransmission of any HDLC frames which are incorrectly received. The network register 4 records the earliest transmitted frame not yet acknowledged by all of the local registers and inhibits transmission of new frames if they fall outside a transmission window relative to the earliest transmitted frame. The network register 4 polls the local registers 10 for retransmission requests and the local registers 10 also send unsolicited requests to the network register 4. The network register 4 only retransmits a frame once if multiple requests for that frame are transmitted within a predetermined period. When a new local register 10 enters the broadcast reception group, the network register 4 informs the new local register 10 which new frame will next be transmitted. The number of bits used for frame sequence numbers is greater than that defined in the HDLC protocols.

Claims

1. Apparatus for broadcasting data to a plurality of data receiving stations, comprising:

means for broadcasting said data in a common channel receivable by each of said receiving stations in a format comprising a plurality of frames;

means for receiving error correction request signals indicating selected ones of said frames from each of said receiving stations; and

means for rebroadcasting said selected frames to each of said receiving stations in response to said error correction request signals;

wherein said means for rebroadcasting is operable, if a plural number of said error correction request signals indicating the same selected frame are received within a predetermined period, to rebroadcast said same selected frame less than said plural number of times said error correction request signals indicating the same selected frame are received within the predetermined period of time.

2. Apparatus as claimed in claim 1, wherein said means for retransmitting is operable to retransmit each selected frame only if said selected frame has not previously been transmitted within said predetermined period.

3. A method of broadcasting data to a plurality of data receiving stations, comprising:

broadcasting said data in a common channel receivable by each of said receiving stations in a format comprising a plurality of frames, receiving error correction request signals indicating selected ones of said frames from one or more of said receiving stations, and rebroadcasting said selected frames to said receiving stations;

wherein, if a plural number of said error correction request signals indicating the same selected frame are received within a predetermined period, the step of retransmitting said selected frames comprises rebroadcasting said same selected frame less than said plural number of times said error correction request signals indicating the same selected frame are received within the predetermined period of time.

4. A method as claimed in claim 3, wherein said retransmitting step comprises retransmitting each selected frame only if that selected frame has not previously been transmitted within said predetermined period.

5. Apparatus for broadcasting data to a plurality of data receiving stations, comprising:

means for broadcasting said data in a common channel receivable by each of said receiving stations in a format comprising a plurality of frames;

means for receiving error correction request signals indicating selected ones of said frames from each of said receiving stations;

means for broadcasting said selected frames to each of said receiving stations in response to said error correction request signals and means for receiving from each of said receiving stations acknowledgment signals indicating the earliest of said frames which has not been received by that station, wherein the means for broadcasting is operable to broadcast a new frame which has not been previously broadcast only if a sequential order of said new frame is not greater than a sequence order of the earliest of said frames which has been indicated to not have been received by any one of said receiving stations by a predetermined number.

6. Apparatus as claimed in any one of claim 5 wherein the data is broadcast from a satellite.

7. Apparatus as claimed in any one of claim 5 wherein the data relates to the status of user terminals in a mobile communications system and each of the receiving stations has associated therewith a database for storing said data.

8. A method of broadcasting data to a plurality of data receiving stations, comprising:

broadcasting said data in a common channel receivable by each of said receiving stations in a format comprising a plurality of frames;

receiving error correction request signals indicating selected ones of said frames from one or more of said receiving stations;

rebroadcasting said selected frames to said receiving stations; and

receiving from each of said receiving stations acknowledgment signals indicating the earliest in sequence of said frames which has not been received by that local station, wherein a new frame which has not previously been broadcast is broadcast only if a sequential order of said new frame is not greater than a sequence order of the earliest of said frames which has been indicated to have not been received by any one of said local stations by a predetermined number.

9. A method as claimed in any one of claim 8 wherein the data is broadcast via satellite.

10. A method as claimed in any one of the claim 8, wherein the data relates to the status of user terminals in a mobile communications system and each of the receiving stations has associated therewith a database for storing said data.