K. Ratnam and I. Matta, "W-TCP: An Efficient Transmission Control Protocol for Networks with Wireless Links," in In Proceedings of Third IEEE Symposium on Computer and Communications, 1998.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....in the kernel, as they augment or modify the transport layer. An interesting point in FT TCP is that the other (non fault tolerant) endpoint of the connection runs TCP without any changes: we cannot provide this property, though, as a broken connection affects both endpoints. The protocols in [12, 13] adapt TCP to wireless environments. Connectivity can be lost in such environments for a long time. The solutions usually passivate the TCP connection when connectivity is lost, to avoid that TCP reacts to this condition by reducing the size of its congestion window or by breaking the connection. ....

K. Ratnam and I. Matta. WTCP: An efficient transmission control protocol for networks with wireless links. Proc. Third IEEE Symposium on Computers and Communications (ISCC '98), Athens, Greece, June 1998.

....3500 4000 Fig. 12. Swift recovery from TCP timeout during a 600KB file transfer while using the proxy. Plots showing (top left and clockwise) a) RTT plot of TCP timeout (b) Outstanding (inflight) data (c) receiver perceived throughput and (d) sender trace. Freeze TCP [25] FDA [27] W TCP [16], WTCP [24] and TCP Westwood [21] are some of the more important ones. Careful examination of existing schemes suggests four broadly different approaches: link layer based schemes (both TCP aware and unaware) e.g. 14] 26] split connection based approaches (e.g. I TCP [20] W TCP [16] and ....

....W TCP [16] WTCP [24] and TCP Westwood [21] are some of the more important ones. Careful examination of existing schemes suggests four broadly different approaches: link layer based schemes (both TCP aware and unaware) e.g. 14] 26] split connection based approaches (e.g. I TCP [20] W TCP [16]) and early warning based approaches (e.g. FreezeTCP [25] and finally those necessitating end system changes (e.g. WTCP [24] Freeze TCP [25] TCP Westwood [21] Snoop [14] is a TCP aware link layer scheme that sniffs packets in the base station and buffers them. If duplicate acknowledgements ....

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K. Ratnam and I. Matta, "W-TCP: An Efficient Transmission Control Protocol for Networks with Wireless Links", In Proceedings of Third IEEE Symposium on Computer and Communications (IEEE ISCC), 1998.

....uses a simple zero window ACK scheme to throttle transmission of data from the wired sender. This leads to stop start stop bursty traffic on the wired connection, and the lack of buffering in the proxy can lead to link under utilization for want of packets to send. Ratnam and Matta propose W TCP [23], which acknowledges a packet to the sender only after receiving an acknowledgement from the mobile host. W TCP changes the timestamp field in the packet to account for the time spent idling at the base station. On the other hand, WTCP [28] is an end to end scheme which primarily uses inter packet ....

K. Ratnam and I. Matta, "W-TCP: An Efficient Transmission Control Protocol for Networks with Wireless Links", In Proceedings of Third IEEE Symposium on Computer and Communications (IEEE ISCC), 1998.

....data (c) receiver perceived throughput and (d) sender trace. VII. RELATED WORK The academic literature contains a plethora of solutions for elevating performance over wireless links. Berkeley s SNOOP [16] delayed dupAcks scheme [21] M TCP [18] I TCP [17] Freeze TCP [20] FDA [22] W TCP [13] and WTCP [19] are some of the more important ones. Careful examination of existing schemes suggests four broadly different approaches: link layer based schemes (both TCP aware and unaware) e.g. 16] 21] split connection based approaches (e.g. I TCP [17] W TCP [13] and early warning based ....

....[20] FDA [22] W TCP [13] and WTCP [19] are some of the more important ones. Careful examination of existing schemes suggests four broadly different approaches: link layer based schemes (both TCP aware and unaware) e.g. 16] 21] split connection based approaches (e.g. I TCP [17] W TCP [13]) and early warning based approaches (e.g. FreezeTCP [20] and finally those necessitating end system changes (e.g. WTCP [19] Freeze TCP [20] Snoop [16] is a TCP aware link layer scheme that sniffs packets in the base station and buffers them. If duplicate acknowledgements are detected, ....

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K. Ratnam and I. Matta, "W-TCP: An Efficient Transmission Control Protocol for Networks with Wireless Links", In Proceedings of Third IEEE Symposium on Computer and Communications (IEEE ISCC), 1998.

....problem somewhat, but does not entirely solve it. Berkeley s Snoop protocol [SNOOP] is a hybrid scheme mixing link layer reliability mechanisms with the split connection approach. It is an improvement over I TCP in that end to end semantics are retained as well as in terms of performance. WTCP [WTCP] is similar to Snoop in that it preserves end to end semantics. In WTCP, the base station uses a complex scheme to hide the time it spends recovering from wireless link errors. It requires changes only at the base station. These schemes require the base station to examine and operate on the ....

Ratnam, K., Matta, I., "WTCP: An Efficient Transmission Control Protocol for Networks with Wireless Links," Technical Report NU-CCS-97-11, Northeastern University, July 1997. Available at: http://www.ece.neu.edu/personal/karu/papers/WTCP-NU.ps.gz 11

....of TCP may skip this TCP for Wireless Networks 2 section without any loss of continuity. In Section 3, we have presented an overview of the splitconnection [6, 7, 8, 9, 11] approaches to solving the problem and have discussed their merits and drawbacks. Sections 4 and 5 talk about the TCP aware [12, 13, 14, 15] and TCP unaware [16] approaches respectively. Section 6 summarizes various Explicit Notification mechanisms [18, 5, 19] In Sections 7 and 8, we discuss generic approaches that distinguish between congestion losses and transmission losses by using two connections [20] and receiver based ....

....do not retain the end to end semantics of TCP even though they shield the fixed host from the losses over wireless links. M TCP [24] follows a completely different set of semantics. Approaches like Fast Retransmits [23] require modification to the TCP code at the sender or mobile host. WTCP [15] is a transmission control protocol, which maintains the end to end semantics of TCP without needing modifications in the TCP code at the hosts. The only modification that is needed is done at the base station. The protocol is somewhat similar to the snoop protocol [13] The drawback with snoop ....

K. Ratnam, and I. Matta, "WTCP: An efficient transmission control protocol for networks with wireless links," IEEE Symp. Computer and Communications (ISCC), June 1998.

....is TCP. Any approach that depends on the base station to 97 perform mediation will not only fail when the traffic is encrypted, but also destroy the end to end semantics. In real networks, support for RFC 1323 in TCP implementations is not yet widespread [MD98] Therefore, proposed schemes [RM97] that depend on the timestamp option in RFC1323 may be greatly limited in practice. Comparatively, the simple modification at the TCP sender stack makes Veno easily deployable in real networks. Any party who is interested in the enhanced performance can single handedly do that by installing the ....

Karunaharan Ratnam, Ibrahim Matta, WTCP: an Efficient Transmission Control Protocol for Networks with Wireless Links, Technical Report NU-CCS-97-11, Northeastern University, July 1997."

....College Station, TX 77843 3112, E mail: vaidya cs.tamu.edu, Phone: 409 845 0512, Fax: 409 847 8578 Microsoft Corporation, Redmond, WA. Mehta performed this work at the Texas A M University. Sun Microsystems Laboratories, Palo Alto Sun Microsystems Laboratories, Palo Alto [17] 19] [21], 25] 26] 27] However, many of these schemes require TCP specific actions on the part of intermediate nodes on the path from TCP sender to TCP receiver. Such schemes are sometimes referred as being TCP aware [3] The objective of this paper is to investigate an alternative TCP unaware ....

....from the base station. This approach, however, violates the end to end reliability semantics of TCP. The Snoop protocol [4] described later in the paper, also performs local recovery, but improves on the split connection approach by retaining the end to end reliability semantics. WTCP [21] modifies the Snoop protocol by timestamping packets. The time stamps are used to provide the sender with a more accurate estimate of round trip times, despite retransmissions on the wireless link. The explicit loss notification (ELN) scheme [3] assumes that the receiver can determine the cause ....

K. Ratnam and I. Matta, "WTCP: An efficient transmission control protocol for networks with wireless links," Tech. Rep. NUCCS -97-11, Northeastern University, July 1997.

....performance. Snoop does two things: 1. Locally (on the wireless link) retransmit lost packets, instead of allowing TCP to do so end to end. 2. Suppress the duplicate acks on their way from the receiver back to the sender, thus avoiding fast retransmit and congestion avoidance at the latter. WTCP [WTCP] is similar to Snoop in that it preserves end to end semantics. In WTCP, the base station uses a complex scheme to hide the time it spends moving packets across the wireless link (this typically includes retransmissions due to error recovery, but may also include time spent dealing with ....

Ratnam, K., Matta, I., "WTCP: An Efficient Transmission Control Protocol for Networks with Wireless Links," Technical Report NU-CCS-97-11, Northeastern University, July 1997. Available at: http://www.ece.neu.edu/personal/karu/papers/WTCP-NU.ps.gz

....error rate, when compared to wired links. Because of its inability to distinguish between packet losses due to congestion and due to transmission errors, TCP performs poorly on wireless links [2, 3] Several interesting approaches have already been proposed to improve TCP performance over wireless [2, 4, 3, 5, 8, 10, 15, 17, 19, 21, 25, 26, 27]. However, many of these schemes require TCP specific actions on the part of intermediate nodes on the path from TCP sender to TCP receiver. Such schemes are sometimes referred as being TCP aware [3] The objective of this paper is to investigate an alternative TCP unaware technique that can ....

....from the base station. This approach, however, violates the end to end reliability semantics of TCP. The Snoop protocol [4] described later in the paper, also performs local recovery, but improves on the split connection approach by retaining the end to end reliability semantics. WTCP [21] modifies the Snoop protocol by time stamping packets. The time stamps are used to provide the sender with a more accurate estimate of round trip times, despite retransmissions on the wireless link. The explicit loss notification (ELN) scheme [3] assumes that the receiver can determine the cause ....

K. Ratnam and I. Matta, "WTCP: An efficient transmission control protocol for networks with wireless links," Tech. Rep. NU-CCS-97-11, Northeastern University, July 1997.

....have shown that TCP goodput can be improved if the cause of packet loss is identified [3] 17] By attributing a packet loss to wireless transmission errors, the TCP source can refrain from taking unnecessary congestion control measures. One set of solutions (e.g. I TCP [2] Snoop [4] WTCP [15]) require support from the base station located at the interface between the wired infrastructure and the wireless access infrastructure. These solutions incur the cost of implementation at the base station, or that of explicit feedback messages to inform the source of the cause of loss, and some ....

K. Ratnam and I. Matta. WTCP: An efficient transmission control protocol for networks with wireless links. Proc. Third IEEE Symposium on Computers and Communications (ISCC '98), Athens, Greece, 1998.

....parameters. 4 Simulation Model and Performance Measures In our evaluations, we used the network simulator ns v.1.2a3 [7] a public domain software from Lawrence Berkeley National Lab. We extended ns to incorporate wireless link characteristics and to simulate WTCP, I TCP, and Snoop. See [8, 9] for more details. We model the wireless link using a two state Markov process, where the channel is in either good state or bad state. We fixed the mean duration of the good state at 1 second. The mean bad state duration is varied from 10 ms to 100 ms. 5 Results and Discussion We have simulated ....

....the fixed or mobile host, WTCP runs on the base station and achieves very high throughput compared to TCP tahoe. We have simulated other protocols (I TCP and Snoop) for comparison purposes. WTCP performs better or as well as other protocols in terms of throughput with only a slight loss in goodput [8]. WTCP effectively hides the time spent by the base station to locally recover so as not to hinder the source s ability to effectively detect congestion in the fixed wireline network. ....

K. Ratnam and I. Matta. WTCP: An efficient transmission control protocol for networks with wireless links. Technical Report NU-CCS-97-11, Northeastern University, 1997. http://www.ece.neu.edu/personal/karu/papers/WTCPNU. ps.gz.

....points (base stations) to locally retransmit the data in order to hide wireless losses from TCP. In this paper, we use extensive simulations to evaluate TCP performance in the presence of congestion and wireless losses when the base station employs one of two proposals, namely Snoop [2] and WTCP [8]. Our results show that WTCP significantly improves the throughput of TCP connections due to its unique feature of hiding the time spent by the base station to locally recover from wireless link errors so that TCP s round trip time estimation at the source is not affected. This proved to be ....

....errors must be detected and retransmitted as quickly as possible. There are many proposals to improve TCP performance over networks with wireless links. Invariably, most of them, in one form or another, rely on the base station to improve performance. We discuss two proposals, Snoop [2] and WTCP [8], that improve TCP performance while maintaining end to end TCP semantics 2 , and require no modification to the TCP code that runs on the end systems (i.e. hosts) In both of these proposals, the base station buffers TCP segments destined for the mobile host and retransmits a segment if the ....

[Article contains additional citation context not shown here]

K. Ratnam and I. Matta. WTCP: An efficient transmission control protocol for networks with wireless links. Technical Report NUCCS -97-11, Northeastern University, July 1997. http://www.ece.neu.edu/personal/karu/papers/WTCPNU. ps.gz.

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K. Ratnam and I. Matta, "W-TCP: An Efficient Transmission Control Protocol for Networks with Wireless Links," in In Proceedings of Third IEEE Symposium on Computer and Communications, 1998.

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Karunaharan Ratnam, Ibrahim Matta, "WTCP: An Efficient Transmission Control Protocol for Networks with Wireless Link.s"

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K. Ratnam and I. Matta, "W-TCP: An Efficient Transmission Control Protocol for Networks with Wireless Links," in In Proceedings of Third IEEE Symposium on Computer and Communications, 1998.

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K. Ratnam and I. Matta, "W-TCP: An Efficient Transmission Control Protocol for Networks with Wireless Links", In rd IEEE Symposium on Computer and Communications (IEEE ISCC), 1998.

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K. Ratnam and I. Matta, "WTCP: An efficient transmission control protocol for networks with wireless links," in Proceedings of 3rd IEEE Symposium on Computers and Communications (ISCC '98), 1998, pp. 74-78.

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K. Ratnam and I. Matta, "W-TCP: An Efficient Transmission Control Protocol for Networks with Wireless Links", In Proceedings of Third IEEE Symposium on Computer and Communications (IEEE ISCC), 1998.

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K. Ratnam and I. Matta. WTCP: An Efficient Transmission Control Protocol for Networks with Wireless Links. Proc. Third IEEE ISCC, 1998.

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K. Ratnam and I. Matta. WTCP: An Efficient Transmission Control Protocol for Networks with Wireless Links. In Proc. of the Third IEEE Symposium on Computers and Communications, pages 74--78, June 1998.

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Ratnam, K., Matta, I., "WTCP: An Efficient Transmission Control Protocol for Networks with Wireless Links," Technical Report NU-CCS-97-11, Northeastern University, July 1997. Available at: http://www.ece.neu.edu/personal/karu/papers/WTCPNU. ps.gz

No context found.

K. Ratnam and I. Matta. WTCP: An Efficient Transmission Control Protocol for Networks with Wireless Links. In Proc. of the Third IEEE Symposium on Computers and Communications, pages 74--78, June 1998.

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