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

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.

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.

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.

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.

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.