Method and system for flow control for route switching

• US 7,382,732 B2
• Filed: 08/16/2002
• Issued: 06/03/2008
• Est. Priority Date: 08/17/2001
• Status: Expired due to Fees

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Matinmikko, Reijo, Wigell, Toomas, Peisa, Janne Johannes
• Primary Examiner(s): Yao; Kwang Bin
• Assistant Examiner(s): Lai; Andrew
• Application Number:
  US10/485,919
• Publication Number:
  US 20040246898A1
• Time in Patent Office: 2,118 Days
• Field of Search: 370235-236, 370/236.1, 370/236.2, 370/237, 370/238, 370/238.1, 370252-253
• US Class Current: 370/236
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1835 Buffer management
• CPC Class Codes: H04L 1/1845 Combining techniques, e.g. code combining
• CPC Class Codes: H04L 2001/0092 Error control systems characterised by the topology of the transmission link
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04W 28/14 using intermediate storage
• CPC Class Codes: H04W 36/26 by agreed or negotiated communication parameters
• CPC Class Codes: H04W 72/52 based on load
• CPC Class Codes: H04W 72/569 of the traffic information

Abstract

The present invention provides flow control for route switching in a communications system using retransmissions. It is well suited for a cellular mobile radio communications system, particularly a Universal Mobile Telecommunications System, UMTS.

Claims

1. A method of minimizing retransmission of data packets in a wireless communications system, said method comprising the step of:

using a flow control process for route switching, wherein said flow control process comprises signals carrying information on i) predicted amount of data to send or ii) information for estimation of amount of data to send, said signals being transmitted to a data receiver, wherein credits for the flow control for route switching are determined based upon at least one parameter selected from the group consisting of;

credits outstanding;

queue length;

queue priority; and

estimated amount of data to send within a predetermined time frame;

wherein said credits are determined such that, for a given prediction time interval and a given prohibit time interval, the queue length at the beginning of the last prohibit time interval of the predetermined prediction time interval is close to a value being fixed for a given duration of the prohibit time interval.

2. The method recited in claim 1, wherein the amount of data to send within the pre-determined time-frame is estimated as a function of at least one parameter selected from the group consisting of:

historical data rate;

historical mean data rate;

maximum data rate of a scheduled channel;

guaranteed data rate; and

default data rate.

3. The method recited in claim 1, wherein said credits are determined such that, for a specified time frame, the queue length is minimized at the end of said time frame.

4. The method recited in claim 1, wherein credits are limited to an estimated amount of data to send within a time frame comprising a prohibit time interval, starting at a time ahead corresponding to at least a round-trip time of a sender-receiver relationship.

5. The method recited in claim 1, wherein when route switching from an old route to a new route, user data in a queue of the old route is discarded and retransmitted over the new route.

6. The method recited in claim 1, wherein the route includes a protocol entity selected from the group consisting of:

a MAC protocol layer;

a MAC-d protocol layer;

a MAC-c/-sh protocol layer;

a MAC-hs protocol layer; and

a hybrid ARQ protocol.

7. The method recited in claim 1, wherein the route includes a radio network controller of a radio communications system.

8. The method recited in claim 1, wherein the route includes a Node B or a base station of a radio communications system.

9. The method recited in claim 1, wherein the route switching process is selected from the group consisting of:

channel switching;

channel type switching;

handover; and

radio cell update.

10. The method recited in claim 1, wherein said method of minimizing retransmission comprises one or more outer retransmission loops.

11. The method recited in claim 10, wherein credits are determined to minimize round trip variability of said one or more outer retransmission loops.

12. The method recited in claim 1, wherein said method of minimizing retransmission comprises one or more inner retransmission loops.

13. The method recited in claim 1, wherein said method of minimizing retransmission comprises two or more cascaded retransmission loops.

14. A network element in a wireless communications system for minimizing retransmission of data packets, said network element comprising:

means for using a flow control process for route switching, wherein said flow control process comprises signals carrying information on i) predicted amount of data to send or ii) information for estimation of amount of data to send, said signals being transmitted to a data receiver, wherein credits for the flow control for route switching are determined based upon at least one parameter selected from the group consisting of;

credits outstanding;

queue length;

queue priority;

estimated amount of data to send within a predetermined time frame;

historical data rate;

historical mean data rate;

maximum data rate of a scheduled channel;

guaranteed data rate; and

default data rate; and

processing means for determining credits such that, for a given time-frame, queue length at the end of the time-frame is minimized;

wherein the processing means for determining credits determines credits such that, for a given prediction time-frame and a given prohibit time interval, queue length at the beginning of the last prohibit time interval of the predetermined prediction time-frame is close to a value being fixed for a given duration of the prohibit time interval.

15. The network element recited in claim 14, wherein the processing means for determining credits determines credits such that they are limited to an estimated amount of data to send within a time frame comprising a prohibit time interval, starting at a time ahead corresponding to at least a round-trip time of a sender-receiver relationship.

16. The network element recited in claim 14, wherein when route switching from an old route to a new route, user data in a queue of the old route is discarded and retransmitted over the new route.

17. The network element recited in claim 14, wherein the route includes a protocol entity selected from the group consisting of:

a MAC protocol layer;

a MAC-d protocol layer;

a MAC-c/-sh protocol layer;

a MAC-hs protocol layer; and

a hybrid ARQ protocol.

18. The network element recited in claim 14, wherein the route includes a radio network controller of a radio communications system.

19. The network element recited in claim 14, wherein the route includes a Node B or a base station of a radio communications system.

20. The network element recited in claim 14, wherein the route switching process is selected from the group consisting of:

channel switching;

channel type switching;

handover; and

radio cell update.

21. The network element recited in claim 14 wherein said retransmission comprises one or more outer retransmission loops.

22. The method recited in claim 21, wherein credits are determined to minimize round trip variability of said one or more outer retransmission loops.

23. The network element recited in claim 14, wherein said retransmission comprises one or more inner retransmission loops.

24. The network element recited in claim 14, wherein said retransmission comprises two or more cascaded retransmission loops.

25. A method of minimizing retransmission of data packets in a wireless communications system, said method comprising the step of:

using a flow control process for route switching, wherein said flow control process comprises signals carrying information on i) predicted amount of data to send or ii) information for estimation of amount of data to send, said signals being transmitted to a data receiver, wherein credits for the flow control for route switching are determined based upon at least one parameter selected from the group consisting of;

credits outstanding;

queue length;

queue priority; and

estimated amount of data to send within a predetermined time frame;

wherein credits are limited to an estimated amount of data to send within a time frame comprising a prohibit time interval, starting at a time ahead corresponding to at least a round-trip time of a sender-receiver relationship.

26. A network element in a wireless communications system for minimizing retransmission of data packets, said network element comprising:

means for using a flow control process for route switching, wherein said flow control process comprises signals carrying information on i) predicted amount of data to send or ii) information for estimation of amount of data to send, said signals being transmitted to a data receiver, wherein credits for the flow control for route switching are determined based upon at least one parameter selected from the group consisting of;

credits outstanding;

queue length;

queue priority;

estimated amount of data to send within a predetermined time frame;

historical data rate;

historical mean data rate;

maximum data rate of a scheduled channel;

guaranteed data rate; and

default data rate; and

processing means for determining credits such that, for a given time-frame, queue length at the end of the time-frame is minimized;

wherein the processing means for determining credits determines credits such that they are limited to an estimated amount of data to send within a time frame comprising a prohibit time interval, starting at a time ahead corresponding to at least a round-trip time of a sender-receiver relationship.