Method for minimizing the number of data packets required for retransmission in a two-way communication system

• US 6,570,843 B1
• Filed: 05/19/1999
• Issued: 05/27/2003
• Est. Priority Date: 05/22/1998
• Status: Expired due to Term

• Current Assignee: KenCast Inc.
• Original Assignee: KenCast Inc.
• Inventors: Wolfgang, H. Lewis
• Primary Examiner(s): Hsu, Alpus H.
• Assistant Examiner(s): Tran, Thien D.
• Application Number:
  US09/314,121
• Time in Patent Office: 1,469 Days
• Field of Search: 370/230, 370/235, 370/249, 370/250, 370/252, 370/389, 370/253, 370/237, 370/238, 370/216, 714/349, 714/746, 714/748, 714/749
• US Class Current: 370/216
• CPC Class Codes: H04L 1/1816 with retransmission of the same, encoded, message
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint

Abstract

A method is provided that reduces the total number of retransmitted packets required for retransmission from a transmitter to a receiver, the transmitter having already transmitted over a forward channel N number of packets to the receiver, and the receiver having already reported over a back channel to the transmitter information regarding which of the N packets were successfully received. Another method is provided that accounts for the likelihood that some of the retransmitted packets may be lost on retransmission, and thus increases the number of retransmitted packets accordingly.

Claims

1. A method for minimizing the number of packets required for retransmission from a transmitter to a receiver, the transmitter having already transmitted over a forward channel N number of packets to the receiver, and the receiver having already reported over a back channel to the transmitter information regarding which of the N packets were successfully received, said method comprising the steps of:

(1) determining from the reported back channel information a number S of successfully received packets;

(2) determining whether S is less that a target packet number T;

(3) if so, determining a projected number of packets P equal to S plus the number of packets that already exist in a packet accumulator and were not successfully received by the receiver;

(4) determining whether P is less than T;

(5) if so, adding to the packet accumulator a packet not successfully received by the receiver and incrementing P by one;

(6) determining whether P is equal to T and if not, repeating step (5) until P is equal to T; and

(7) wherein N, P, S and T are integers and greater than 0.

2. A method according to claim 1, wherein a data file comprises a plurality of shares of packets, and the number N represents the number of packets transmitted for any one of those shares.

3. A method according to claim 2, wherein steps (1) through (6) are repeated for each share of the data file.

4. A method according to claim 1, wherein the N number of packets is transmitted over a plurality of forward channels to a respective plurality of receivers, and at least one of the receivers has already reported over a respective back channel to the transmitter information regarding which of the N packets were successfully received by that receiver, and wherein steps (1) through (6) are repeated for each reporting receiver.

5. A method for minimizing the number of packets required for retransmission from a transmitter to a receiver, the transmitter having already transmitted over a forward channel N number of packets to the receiver, and the receiver having already reported over a back channel to the transmitter information regarding which of the N packets were successfully received, said method comprising the steps of:

(1) determining from the reported back channel information a number S of successfully received packets;

(2) determining whether S is less than a target packet number T;

(3) if so, determining a projected number of packets P equal to S plus the number of packets that already exist in a packet accumulator and were not successfully received by the receiver;

(4) determining a boost number of packets H;

(5) determining whether P is less that (T+H);

(6) if so, adding to the packet accumulator a packet not successfully received by the receiver and incrementing P by one;

(7) determining whether P is equal to (T+H) or whether P is equal to N, and if both such determinations are no, repeating step (6) until either P is equal to (T+H) or P is equal to N; and

(8) wherein H, N, P, S and T are integers and greater than 0.

6. A method according to claim 5, wherein a data file comprises a plurality of shares of packets, and the number N represents the number of packets transmitted for any one of those shares.

7. A method according to claim 6, wherein steps (1) through (7) are repeated for each share of the data file.

8. A method according to claim 7, wherein H is equal to the smallest integer greater than a bracketed quantity {(TPL*(TPL−

TNE))/(TNP*TNS)}, if the bracketed quantity is greater than zero, or H is equal to 1, if the bracketed quantity is zero or less, wherein TPL=“

Total Packets Loss”

by the receiver during transmission of all shares of packets of the data file, TNS=“

Total Number of Shares”

=in the data file, TNE =“

Total Number of Extra”

packets transmitted, whereby TNE is equal to (N−

T)*TNS, and TNP =“

Total Number of Packets”

, which is equal to N*TNS.

9. A method according to claim 5, wherein the N number of packets is transmitted over a plurality of forward channels to a respective plurality of receivers, and at least one of the receivers has already reported over a respective back channel to the transmitter information regarding which of the N packets were successfully received by that receiver, and wherein steps (1) through (7) are repeated for each reporting receiver.