Data transmission system with sliding-window data flow control

• US 5,930,233 A
• Filed: 01/06/1997
• Issued: 07/27/1999
• Est. Priority Date: 05/09/1995
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Kari, Hannu, Vainikka, Jari, Ahopelto, Juha-Pekka, Kanerva, Mikko
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): YAO, KWANG BIN
• Application Number:
  US08/765,067
• Time in Patent Office: 932 Days
• Field of Search: 370/347, 370/229, 370/235, 370/236, 370/310, 370/410, 370/464, 370/465, 370/468, 370/498, 370/503, 370/516, 370/517, 370/522, 370/216, 370/345, 370/231, 370/394, 371/32, 371/33, 395/200.62, 395/200.64
• US Class Current: 370/231
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/27 Evaluation or update of window size, e.g. using information derived from acknowledged [ACK] packets
• CPC Class Codes: H04L 47/34 ensuring sequence integrity, e.g. using sequence numbers

Abstract

In a digital data transmission system using sliding-window flow control with an adjustable window size on a non-transparent data connection whose nominal data transmission rate may vary during the connection, a receiving party delays the transmission of a retransmission request for a missing frame for the duration of a delay, so that the receiving party may ensure that the missing frame has not been moved to be sent later in the same group or in next groups. If the missing frame is received later in the same group or in the next groups within said delay, no retransmission request is sent. If the missing frame is not received by the end of the delay, a retransmission request is sent. This eliminates unnecessary retransmissions due to the wrong frame order, and resulting loading or congestion. This results in a higher throughput on the data connection. If grouping is not being used, retransmission is not delayed unless a delay is needed for another reason.

Claims

1. A digital data transmission system, said system comprising:

a transmitting party;

a receiving party;

a non-transparent circuit-switched data connection between said transmitting and receiving parties for transmitting and receiving data in data frames;

a data flow control protocol involving transmitting said data frames by said transmitting party in a preset order on said data connection, checking the order of receiving of said data frames by said receiving party, based on order information included in said data frames, acknowledging by said receiving party properly received data frames, and retransmitting erroneous or missing data frames by said transmitting party;

said transmitting party being capable of temporarily grouping data frames being transmitted; and

said receiving party being arranged to send, upon detecting a missing data frame, based on order information included in each respective two of said data frames received in succession, a retransmission request for said missing data frame only after a delay of a predetermined duration, wherein said delay of said predetermined duration is for ensuring that said missing frame has not been transmitted in a manner which would result in said missing frame being received by said receiving party subsequent to said receiving party receiving the second of said respective two of said data frames received in succession, if said transmission request was not sent and wherein said predetermined duration of said delay is dependent on said grouping of said data frames by said transmitting party.

2. The system as claimed in claim 1, wherein:

said predetermined duration of said delay is such that said receiving party is arranged to receive so large number of data frames as to ensure that said missing data frame is not received later in a same group of data frames received or in a subsequent group of data frames received.

3. The system as claimed in claim 1, wherein:

said transmitting party is arranged to transmit said data frames in groups of N frames per group; and

said predetermined duration of said delay is on the order of N frames.

4. The system as claimed in claim 1, wherein:

said data transmission system is a multiple access mobile communication system;

said data connection comprises at least one of a plurality of traffic channels on a radio path;

said transmitting party is arranged to provide that said grouping involves sending said data frames via N parallel ones of said traffic channels; and

said predetermined duration of said delay is on the order of N frames.

5. The system as claimed in claim 1, wherein:

said predetermined duration of said delay is equal to the time needed for receiving a given number of said data frames by said receiving party.

6. The system as claimed in claim 1, wherein:

said receiving party is arranged to determine the expiration of said predetermined duration of said delay by counting data frames received from said transmitting party.

7. The system as claimed in claim 1, wherein:

said transmitting party is a terminal adaptation function in a mobile station; and

said receiving party is an interworking function in a mobile communication network.

8. The system as claimed in claim 1, wherein:

said transmitting party is an interworking function in a mobile communication network; and

said receiving party is a terminal adaptation function in a mobile station.

9. A receiver for a digital data transmission system, said receiver comprising:

an arrangement for receiving data frames transmitted in a preset nominal order by a transmitting party; and

an arrangement for sending, upon detecting a missing data frame based on order information in any respective two data frames received in succession, a retransmission request to said transmitting party for said missing data frame, only after expiration of a delay having a predetermined duration, for ensuring that said missing data frame has not been sent after the second data frame in said respective two data frames received in succession, wherein said predetermined duration of said delay is arranged for said receiver to be dependent on and therefore predetermined by the grouping of data frames used by said transmitting party.

10. The receiver as claimed in claim 9, wherein:

said arrangement for receiving is arranged to receive said transmitted data frames when said transmitted data frames are transmitted in groups; and

said predetermined duration of said delay corresponds to the time normally adequate for receiving a given number of said data frames, said given number of data frames being sufficiently high to ensure said missing data frame is not received in a current group or in a subsequent group of said data frames.

11. The receiver as claimed in claim 10, wherein:

said arrangement for receiving is arranged to receive said transmitted data frames when said transmitted data frames are transmitted in groups of N frames; and

said predetermined duration of said delay is on the order of the time normally adequate for receiving N received data frames.

12. The receiver as claimed in claim 9, wherein:

said receiver for a multiple access mobile communication system;

said receiver is arranged to receive data frames over a data connection provided by N parallel traffic channels on a radio path, N being a positive integer; and

said predetermined duration of said delay is approximately equal to the time normally adequate for receiving N data frames.

13. The receiver as claimed in claim 9, wherein:

said predetermined duration of said delay is arranged to be predetermined by counting by said receiver of said received data frames until a predetermined number is thereby counted.

14. A data reception method in a digital data transmission system, said method comprising:

receiving by a receiving party data frames transmitted in a present nominal order by a transmitting party;

checking by said receiving party of the actual order of said received data frames, based on order information included in said received data frames;

detecting by said receiving party of a missing data frame based on said order information as included in a respective two of said received data frames which, as actually received by said receiving party, are received in immediate succession;

delaying by said receiving party, sending of a retransmission request in regard to said missing data frame for a delay period of predetermined duration, and sending said retransmission request for said missing data frame only if said missing frame is not received by said receiving party by the end of said delay period, and sending no said retransmission request when said missing frame is received by said receiving party within said delay period; and

causing said delay period to depend on the grouping of data frames used for transmitting of data frames by said transmitting party.

15. The method as claimed in claim 14, said method further comprising:

transmitting by said transmitting party said data frames in groups;

setting said delay to correspond to a given number of received data frames, said given number of data frames being sufficiently high to ensure that said missing data frame is not received in a current group or in a subsequent group of said received data frames.

16. The method as claimed in claim 14, said method further comprising:

transmitting by said transmitting party said data frames in groups of N frames per group; and

setting said delay period on the order of the time period normally needed for receiving by said receiving party of N said received data frames.

17. The method as claimed in claim 14, wherein said receiver is a receiver for a multiple access mobile communication system, wherein:

said receiving includes receiving data frames over a data connection provided by N parallel traffic channels on a radio path, N being a positive integer; and

said delaying includes setting said delay period to be approximately the time period normally needed for receiving by said receiving party of data frames.

18. The method as claimed in claim 14, said method further comprising:

counting off said delay period by said receiving party, by counting said received data frames.

19. A digital data transmission system using sliding-window flow control, said system comprising:

a transmitting party;

a receiving party;

a non-transparent data connection between said transmitting party and said receiving party;

said transmitting party being provided with a capability to temporarily group data frames transmitted by said receiving party in a preset nominal order to said receiving party over said data connection;

said receiving party being arranged to receive said data frames transmitted by said transmitting party;

said receiving party being arranged to check the actual order of said received data frames based on information included in said received data frames;

said receiving party being arranged to send, upon detecting a missing data frame based on said order information in a respective two of said received data frames received in immediate succession, a retransmission request for said missing data frame only after expiration of a delay period which is sufficient for allowing said missing data frame to be received later in a current group of received data frames or in a subsequent group of data frames, in case the order of said received data frames is different from said preset nominal order of the data frames due to grouping by said transmitting party or characteristics of said data connection, wherein said system is arranged to cause said delay period to be defined in duration by counting said received data frames by said receiving party.

20. The system as claimed in claim 19, said system further comprising:

causing said delay period to correspond in duration to the time needed by said receiving party for receiving a given number of said received data frames, said given number of data frames being sufficiently high to ensure that said missing data frame is not received in a current group or in one of a subsequent group of received data frames.

21. The system as claimed in claim 19, wherein:

said transmitting party is arranged to transmit said data frames in groups of N frames per group; and

said delay period is of a duration on the order of that normally needed by said receiving party for receiving data frames.

22. The system as claimed in claim 19, wherein:

said receiving party is a receiving party for a multiple access mobile communication system;

said data connection is provided by N parallel traffic channels on a radio path, N being a positive integer; and

said delay period is approximately equal to the time normally needed by said receiving party for receiving N data frames.

23. The system as claimed in claim 19, wherein:

said system is arranged to cause said delay period to be dependent in duration on how the data frames transmitted by said transmitting party are groups by said transmitting party.