Performance enhancement of transmission control protocol (TCP) for wireless network applications

• US 6,757,248 B1
• Filed: 06/14/2000
• Issued: 06/29/2004
• Est. Priority Date: 06/14/2000
• Status: Expired due to Fees

• Current Assignee: Nokia Internet Communications (Nokia Corporation)
• Original Assignee: Nokia Internet Communications (Nokia Corporation)
• Inventors: Wu, Jing, Li, Xiang, Cheng, Shiduan, Ma, Jian
• Primary Examiner(s): HO, DUC CHI
• Application Number:
  US09/594,443
• Time in Patent Office: 1,476 Days
• Field of Search: 370/229, 370/230, 370/235, 370/231, 370/394, 370/392, 370/333, 370/252, 370/401, 370/466, 370/395.1, 709/235, 709/234, 714/748, 714/749
• US Class Current: 370/235
• CPC Class Codes: H04L 1/1858 Transmission or retransmission of more than one copy of acknowledgement message
• CPC Class Codes: H04L 1/187 Details of sliding window management
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/18 End to end
• CPC Class Codes: H04L 47/193 at the transport layer, e.g. TCP related
• CPC Class Codes: H04L 47/263 Rate modification at the source after receiving feedback
• 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 47/37 Slow start
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/163 In-band adaptation of TCP data exchange; In-band control procedures
• CPC Class Codes: H04L 69/168 specially adapted for link layer protocols, e.g. asynchronous transfer mode [ATM], synchronous optical network [SONET] or point-to-point protocol [PPP]
• CPC Class Codes: H04W 28/0242 Determining whether packet losses are due to overload or to deterioration of radio communication conditions
• CPC Class Codes: H04W 28/10 Flow control between communication endpoints
• CPC Class Codes: H04W 8/04 Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation

Abstract

A new Fast Recovery Plus (FR+) mechanism, and associated method, for wireless and/or mobile network applications to control data flow and avoid network congestion in a TCP/IP packet-switched network.

Claims

1. A method of flow control and congestion avoidance congestion in a network, comprising:

transmitting, at a source node, data packets to a destination node, via at least an intermediate node;

receiving, at the destination node, data packets transmitted from the source node, via the intermediate node, and generating a duplicate ACK back to the source node to inform the source node that a data packet was received out-of-order in the network and serves as an indication that a data packet has been lost;

upon receipt of a designated number of duplicate ACKs, at the source node, determining that a data packet has been lost;

initializing a counter, at the source node, and recording a congestion window CWND, a slow start threshold Ssthresh, and a maximal sequence number SN that has been sent into the network;

upon receipt of a next duplicate ACK, at the source node, recording its acknowledged sequence number ACK_SN;

determining, at the source node, if the acknowledged sequence number ACK_SN is no more than a recorded sequence number SN;

if the acknowledged sequence number ACK_SN is more than the recorded sequence number SN, incrementing the counter, at the source node, and re-transmitting a lost packet;

if the acknowledged sequence number ACK_SN is no more than the recorded sequence number SN, determining if the packet loss is due to a transmission error; and

if the packet loss is due to the transmission error, setting, at the source node, the slow start threshold Ssthresh to Max(CWND, (Ssthresh+CWND)/2), wherein said CWND and Ssthresh exhibit values previously recorded.

2. The method as claimed in claim 1, wherein said counter is set to record the number of times of packet re-transmission invoked by the duplicate ACKs.

3. The method as claimed in claim 1, wherein said packet loss is due to the transmission error, when the value of the counter is no more than a pre-defined packet threshold indicating the threshold of packet loss.

4. The method as claimed in claim 1, wherein said network corresponds to a TCP/IP packet-switched network for wireless and/or mobile network applications.

5. The method as claimed in claim 1, wherein said slow start threshold Ssthresh is set to no more than Max(FlightSize/2, 2*SMSS), wherein said FlightSize indicates the amount of outstanding data in the network, and said SMSS indicates the size of a largest data segment that can be transmitted.

6. The method as claimed in claim 1, wherein said packet loss is due to congestion, when the value of the counter is more than a pre-defined packet threshold indicating the threshold of packet loss.

7. The method as claimed in claim 6, wherein said congestion window CWND is reduced to halve (½

), and said slow start threshold Ssthresh is reduced to said congestion window to slow a transmission rate to avoid congestion in the network, when said packet loss is due to congestion.

8. The method as claimed in claim 1, wherein said network corresponds to one or more TCP/ATM network, TCP/ISF network, and satellite network for wireless and/or mobile network applications.

9. A method of flow control and congestion avoidance a source node in a network including a destination node, comprising:

upon receipt of duplicate ACKs from a destination node indicating that a data packet has been lost, re-setting a counter and recording a congestion window CWND, a slow start threshold Ssthresh, and a current maximal sequence number SN that has been sent into the network;

upon receipt of a next duplicate ACK, at the source node, recording its acknowledged sequence number ACK_SN;

determining if the acknowledged sequence number ACK_SN is no less than a recorded sequence number SN;

if the acknowledged sequence number ACK_SN is no less than the recorded sequence number SN, incrementing the counter, and re-transmitting a lost packet;

if the acknowledged sequence number ACK_SN is no more than the recorded sequence number SN, determining if the packet loss is due to a transmission error; and

if the packet loss is due to the transmission error, setting the slow start threshold Ssthresh to Max(CWND, (Ssthresh+CWND)/2), wherein said CWND and Ssthresh exhibit values previously recorded.

10. The method as claimed in claim 9, wherein said counter is set to record the number of times of packet re-transmission invoked by the duplicate ACKs.

11. The method as claimed in claim 9, wherein said packet loss is due to the transmission error, when the value of the counter is no more than a pre-defined packet threshold indicating the threshold of packet loss.

12. The method as claimed in claim 9, wherein said packet loss is due to congestion, when the value of the counter is more than a pre-defined packet threshold indicating the threshold of packet loss.

13. The method as claimed in claim 12, wherein said congestion window CWND is reduced to halve (½

), and said slow start threshold Ssthresh is reduced to said congestion window to slow a transmission rate to avoid congestion in the network, when said packet loss is due to congestion.

14. The method as claimed in claim 9, wherein said network corresponds to one or more TCP/ATM network, TCP/ISF network, and satellite network for wireless and/or mobile network applications.

15. A data network for wireless and/or mobile network applications, comprising:

a source node for transmitting data packets;

a destination node for receiving the data packets from the source node and generating duplicate ACKs when the arrival of data packets is out-of-order; and

at least one intermediate node disposed between said source node and said destination node;

wherein said source node includes a Fast Recovery Plus (FR+) algorithm which, when activated upon receipt duplicate ACKs, performs the following;

initializing a counter and recording a congestion window CWND, a slow start threshold Ssthresh, and a current maximal sequence number SN that has been sent into the network;

upon receipt of a next duplicate ACK, recording its acknowledged sequence number ACK_SN;

determining if the acknowledged sequence number ACK_SN is no less than a recorded sequence number SN;

if the acknowledged sequence number ACK_SN is no less than the recorded sequence number SN, incrementing the counter, and re-transmitting a lost packet;

if the acknowledged sequence number ACK_SN is no more than the recorded sequence number SN, determining if the packet loss is due to a transmission error; and

if the packet loss is due to the transmission error, setting the slow start threshold Ssthresh to Max(CWND, (Ssthresh+CWND)/2), wherein said CWND and Ssthresh exhibit values previously recorded.

16. The data network as claimed in claim 15, wherein said counter is set to record the number of times of packet re-transmission invoked by the duplicate ACKS.

17. The data network as claimed in claim 15, wherein said packet loss is due to the transmission error, when the value of the counter is no more than a pre-defined packet threshold indicating the threshold of packet loss.

18. The data network as claimed in claim 15, wherein said packet loss is due to congestion, when the value of the counter is more than a pre-defined packet threshold indicating the threshold of packet loss.

19. The data network as claimed in claim 15, wherein said congestion window CWND is reduced to halve (½

), and said slow start threshold Ssthresh is reduced to said congestion window to slow a transmission rate to avoid congestion in the network, when said packet loss is due to congestion.

20. A computer readable medium having an enhanced Fast Recovery Plus (FR+) algorithm for wireless network applications, via a network, when executed by a host system, performs:

upon receipt of duplicate ACKs from a remote system, determining that a data packet has been lost;

initializing a counter, and recording a congestion window CWND, a slow start threshold Ssthresh, and a maximal sequence number SN that has been sent into the network;

upon receipt of a next duplicate ACK, recording its acknowledged sequence number ACK_SN;

determining if the acknowledged sequence number ACK_SN is no more than a recorded sequence number SN;

if the acknowledged sequence number ACK_SN is more than the recorded sequence number SN, incrementing the counter, and re-transmitting a lost packet;

if the acknowledged sequence number ACK_SN is no more than the recorded sequence number SN, determining if the packet loss is due to a transmission error; and

if the packet loss is due to the transmission error, setting the slow start threshold Ssthresh to Max(CWND, (Ssthresh+CWND)/2), wherein said CWND and Ssthresh exhibit values previously recorded.

21. The computer usable medium as claimed in claim 20, wherein said counter is set to record the number of times of packet re-transmission invoked by the duplicate ACKs.

22. The computer usable medium as claimed in claim 20, wherein said packet loss is due to the transmission error, when the value of the counter is no more than a pre-defined packet threshold indicating the threshold of packet loss.

23. The computer usable medium as claimed in claim 20, wherein said packet loss is due to congestion, when the value of the counter is more than a pre-defined packet threshold indicating the threshold of packet loss.

24. The computer usable medium as claimed in claim 20, wherein said congestion window CWND is reduced to halve (½

), and said slow start threshold Ssthresh is reduced to said congestion window to slow a transmission rate to avoid congestion in the network, when said packet loss is due to congestion.

25. A host system comprising:

a processor for generating data;

a network module connected to a remote system, via a network, having a data recovery mechanism installed therein for flow control and congestion avoidance in the network, the data recovery mechanism, activated when a data packet has been lost, performing the following;

recording a congestion window “

CWND” and

a slow start threshold “

Ssthresh”

set to regulate a transmission rate of data packets to avoid congestion in the network;

determining if the data packet loss is due to a transmission error; and

if the data packet loss is due to a transmission error, setting the slow start threshold “

Ssthresh”

to Max(“

CWND”

, (“

Ssthresh”

+“

CWND”

)/2), wherein the congestion window “

CWND” and

the slow start threshold “

Ssthresh”

exhibit values previously recorded.

26. The host system as claimed in claim 25, wherein the congestion window “

CWND”

is reduced to halve (½

), and the slow start threshold “

Ssthresh”

is reduced to the congestion window to slow a transmission rate of data packets to avoid congestion in the network, when the data packet loss is due to congestion.

27. The host system as claimed in claim 25, wherein said network corresponds to one or more TCP/ATM network, TCP/ISF network, and satellite network for wireless and/or mobile network applications.

28. A packet-switched telecommunication network comprising:

network nodes interconnected by transmission links;

user terminals connected to the network nodes, said user terminals acting as source nodes which transmit data packets and destination nodes which receive data packets;

wherein each user terminal includes a data recovery mechanism installed therein for flow control and congestion avoidance in the network, and activated when data packets have been lost, said data recovery mechanism performing the following;

recording a congestion window “

CWND” and

a slow start threshold “

Ssthresh”

set to regulate a transmission rate of data packets to avoid congestion in the network;

determining if the data packet loss is due to a transmission error; and

if the data packet loss is due to a transmission error, setting the slow start threshold “

Ssthresh”

to Max(“

CWND”

, (“

Ssthresh”

+“

CWND”

)/2), wherein the congestion window “

CWND” and

the slow start threshold “

Ssthresh”

exhibit values previously recorded.

29. The packet-switched telecommunication network as claimed in claim 28, wherein the congestion window “

CWND”

is reduced to halve (½

), and the slow start threshold “

Ssthresh”

is reduced to the congestion window to slow a transmission rate of data packets to avoid congestion in the network, when the data packet loss is due to congestion.

30. The packet-switched telecommunication network as claimed in claim 29, wherein the slow start threshold Ssthresh is set to no more than Max(FlightSize/2, 2*SMSS), where the FlightSize indicates the amount of outstanding data in the network, and the SMSS indicates the size of a largest data segment that can be transmitted via the network.