B. S. Bakshi, P. Krishna, N. H. Vaidya, and D. K. Pradhan, "Improving performance of TCP over wireless networks," in International Conference on Distributed Computing Systems, 1997.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....mainly classified as link layer mechanisms, transport layer mechanisms, and also newer versions of TCP. Snoop [3] Delayed Duplicate Acknowledgments [23] and TULIP [19] are examples of link layer mechanisms. I TCP [9] and M TCP [4] Explicit Loss Notification [6] Explicit Bad State Notification [5] and Explicit Congestion Notification [22] are examples of transport layer mechanisms. Although newer TCP versions have been proposed to address specific issues related to wireless problems [20] 2] the main interest is in improving the performance of widely used TCP versions, such as TCP ....

....are outlined along with their main advantages and disadvantages. Transport layer approaches include split connection mechanisms, such as I TCP [4] and MTCP [9] and end to end explicit notification mechanisms, such as Explicit Loss Notification (ELN) 3] Explicit Bad State Notification (EBSN) [5], and Explicit Congestion Notification (ECN) 22] In general, split connection mechanisms 5000 10000 15000 20000 25000 0 20 40 60 80 100 120 140 160 Sequence Number Time(Seconds) Tahoe Reno Newreno Sack Vegas Fig. 1. TCP Performance over Wireless Networks have not been used because ....

B. S. Bakshi, N. Vaidya, and D. K. Pradhan. Improving the Performance of TCP over Wireless Networks. In Proceedings of 17th. International Conference on DCS, pages 365--373, July 1997.

....the base station and the mobile node. In contrast, ad hoc networks are multi hop networks in which data has to be transmitted over several wireless links, from the sender to the receiver. The proposed solutions in literature can be subdivided into different classes: i) SplitConnection solutions [2, 9] subdivide the whole communication at the base station in two parts, a fixed network part and a mobile network part. To increase the performance of TCP the base station retransmits packets when packet loss occurs. ii) Local repetitions [4, 15] try to improve the performance of TCP by hiding the ....

B. S. Bakshi, P. Krishna, N. H. Vaidya, and D. Pradhan. Improving performance of TCP over wireless networks. In Proceedings of the 17th International Conference on Distributed Computing Systems (ICDCS '97), 1997.

....all arriving packets. For a large wireless network, a base station may have hundreds of flows going through it and this burden may be too heavy to be practical. At the endhost, approaches have been proposed which differentiate between losses due to packet corruption and losses due to congestion[11 15]. If a loss is caused by congestion, the TCP sender reduces its congestion window. If a loss is due to packet corruption, the TCP sender retransmits the lost packet and does not shrink its congestion window. Channel Quality Based Adaptation of TCP with Loss Discrimination Although these protocols ....

....models. Base Station The delay of the wired link is 40 ms. The mac layer protocol is 802.11 3 4 1 2 (a) b) Figure 3: the Network Topology of Simulations The simulation results in this section compare the performance of three protocols: TCP New Reno, TCP EBSN and TCP ELSA. In TCP EBSN [15], the base station sends a ELN message, which is called Explicit Bad State Notification (EBSN) in [15] to the TCP sender when a packet is lost and retransmits the packet until it is successfully delivered to the sender. Upon receiving the EBSN, the TCP sender reset its retransmission timer so ....

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Bakshi, B.S., et al. Improving performance of TCP over wireless networks. in 17th International conference on distributed computing systems.may, 1997.

....over Wireless A Comparision of the schemes have attempted to improve start up performance for TCP ows. A careful examination of the existing schemes suggests four broadly di erent approaches to improve TCP performance: link layer based schemes (both TCP aware and unaware) e.g. 22] [35]) split connection based approaches (e.g. I TCP [31] W TCP [26] and early warning based approaches (e.g. FreezeTCP [34] and nally those necessitating end system changes (e.g. WTCP [33] Freeze TCP [34] Snoop [22] is a TCP aware link layer scheme that sni s packets in the base station ....

.... long thin wide area wireless links. As such, it does not address the problems of excess queueing at base stations or proxies. Jian Hao et al. developed FDA [36] which uses a Snoop like strategy, but uses a novel ow control scheme which goes some way to prevent excess queueing. Delayed DupAcks [35] is a TCP unaware link layer scheme: during radio losses, it suppresses DupAck s for some interval d, which unfortunately is dicult to determine. The second broad approach is to split the TCP connection into two sections. This allows wireless losses to be completely shielded from the wired ones. ....

V. Bakshi, P. Krishna, N. H. Vaidya, D. K. Pradhan, \Improving Performance of TCP over Wireless Networks", Texas A&M University Tech. Report TR-96-014, May 1996

....should be compared with the similar scenario without the proxy previously shown in figure 3 recovery is significantly quicker. VII. RELATED WORK The academic literature contains a plethora of solutions for elevating performance over wireless links. Berkeley s SNOOP [14] delayed dupAcks scheme [26], M TCP [23] I TCP [20] Timeout Link condition deteriorates after recovery from timeouts Higher Perceived RTTs 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 00:0000:00 01:0001:00 02:0002:00 03:0003:00 rtt 1000 2000 3000 4000 5000 6000 7000 8000 9000 Data (bytes) ....

....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 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 ....

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V. Bakshi, P. Krishna, N. H. Vaidya and D. K. Pradhan, "Improving Performance of TCP over Wireless Networks", Texas A&M University Tech. Report TR-96-014, May 1996

....to (8) For w 2 T and E[Y ] T , F Y [ 1. Thus (from (8) P TD (w 2 ) e = 0.86 as indicated in the figure. Since PNL (w 2 ) 0 for w 2 T , 0.86 = 0.14. Figure 9 presents an analysis of the effect of TCP packet size. We show that, unlike previous results (e.g. [24]) a larger packet size always results in a higher throughput, assuming the same channel fading rate. To show this, we fix C = 1 Mbps, # = 0.1 sec and # = 1.6, and investigate the behavior of various parameters of interest for different choices of E[Y ] and f (only one set of results is shown due ....

....combined result in nonlinear throughput increase as a function of the packet size. Figure 5 shows that the goodput for channels with memory (e.g. fading channels) exhibits saturation for a fixed f as E[Y ] and E[X] increase (this observation has been also noted in some previous works e.g. [24]) The reason for this is evident when E[X] is sufficiently large, TCP goodput in the good state approaches that of an ideal channel, which we denote by # ideal . Also, since the good states are long, all good states are sampled. Hence, for a fixed f , # ceil for slow channel transition ....

B.S. Bakshi, P. Krishna, N.H. Vaidya, and D.K. Pradhan, "Improving performance of TCP over wireless networks," in Proceedings of the 17th International Conference on Distributed Computing Systems, 1997, pp. 365--73.

....because of limited available radio resource it is unlikely that such channels will ever provide the levels that can be offered by wired connections. Besides the low capacity, a wireless interface has also inherent high Bit Error Rates (BERs) which results to significant performance degradation [1,2]. The data recovery mechanism that resides within higher protocol layers (TCP) takes no account of any other media than wired networks. Consequently packet loss is attributed only to congestion and the flow control mechanism effectively constricts the data flow of the session. For these reasons ....

B.S. Bakshi, P. Krishna, N.H. Vaidya, D.K.Pradhan, "Improving performance of TCP over wireless networks", Proceedings of the 17th International Conference on Distributed Computing Systems (Cat. No.97CB36053). IEEE Comput. Soc. Press, Los Alamitos, CA, USA; 1997; xvii+596 pp. p.365-73.

....exists for TCP over wireless; however, none of the schemes looked into improving start up performance for TCP ows. A careful examination of the existing schemes suggests four broadly di erent approaches to improve TCP performance: link layer based schemes (both TCP aware and unaware) e.g. [29, 34]) split connection based approaches (e.g. I TCP [30] W TCP [12] and early warning based approaches (e.g. FreezeTCP [33] and nally those necessitating end system changes (e.g. WTCP [32] Freeze TCP [33] Snoop [29] is a TCP aware link layer scheme that sni s packets in the base station and ....

.... long thin wide area wireless links. As such, it does not address the problems of excess queueing at base stations or proxies. Jian Hao et al. developed FDA [35] which uses a Snoop like strategy, but uses a novel ow control scheme which goes some way to prevent excess queueing. Delayed DupAcks [34] is a TCP unaware link layer scheme: during radio losses, it suppresses DupAck s for some interval d, which unfortunately is dicult to determine in practice. The second broad approach is to split the TCP connection into two sections. This allows wireless losses to be completely shielded from the ....

V. Bakshi, P. Krishna, N. H. Vaidya, D. K. Pradhan, \Improving Performance of TCP over Wireless Networks", Texas A&M University Tech. Report TR-96-014, May 1996

....based solutions that can overcome or even optimise such bottlenecks and, 4) experimentally demonstrating the overall efficacy of our solution. II. RELATED WORK A. TCP Enhancement Schemes over Wireless A number of schemes have been proposed to improve TCP performance over wireless (see, 25] [30], 26] 27] 28] 29] 31] Snoop [25] is a TCP aware link layer scheme that sniffs packets in the base station and buffers them. If duplicate 2 acknowledgements are detected, incoming packets from the mobile host are retransmitted if they are present in a local cache. On the wired side, ....

....[13] wide area wireless links. As such, it does not address the problems of excess queueing at base stations or proxies. Jian Hao et al. developed FDA [31] which uses a Snoop like strategy, but uses a novel flow control scheme which goes some way to prevent excess queueing. Delayed DupAcks [30] is a TCP unaware link layer scheme: during radio losses, it suppresses DupAck s for some interval d, which unfortunately is difficult to determine. The second broad approach is to split the TCP connection into two sections. This allows wireless losses to be completely shielded from the wired ....

[Article contains additional citation context not shown here]

V. Bakshi, P. Krishna, N. H. Vaidya, D. K. Pradhan, "Improving Performance of TCP over Wireless Networks", Texas A&M University Tech. Report TR-96-014, May 1996

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Bakshi, B., P., Krishna, N., Vaidya, N., Pradhan, D.K., "Improving Performance of TCP over Wireless Networks," Technical Report 96-014, Texas A&M University, 1996.

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B. S. Bakshi, P. Krishna, N. H. Vaidya, and D. K. Pradhan, "Improving performance of TCP over wireless networks," in International Conference on Distributed Computing Systems, 1997.

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B. S. Bakshi, P. Krishna, N. H. Vaidya, and D. K. Pradhan, "Improving performance of TCP over wireless networks," in International Conference on Distributed Computing Systems, 1997.

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B. Bakshi, P. Krishna, N. Vaidya, and D. Pradhan. Improving performance of TCP over wireless networks. In Proceedings of IEEE ICDCS, Baltimore, MD, USA, May 1997.

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Bakshi, B.a.P.K.a.N.V.a.D.P. Improving Performance of TCP over Wireless Networks. in 17th International Conference on Distributed Computing Systems (ICDCS). 1997.

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V. Bakshi, P. Krishna, N. H. Vaidya and D. K. Pradhan, "Improving Performance of TCP over Wireless Networks", In IEEE Conference on Distributed Computing Systems (ICDCS 1997.

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V. Bakshi, P. Krishna, N. H. Vaidya, D. K. Pradhan, "Improving Performance of TCP over Wireless Networks", Texas A&M University Tech. Report TR-96-014, May 1996

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B. Bakshi and P. Krishna and N. Vaidya and D. Pradham, "Improving Performance of TCP over Wireless Networks", 17th International Conference on Distributed Computing Systems (ICDCS), May 1997.

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B. Bakshi, P. Krishna, N. H. Vaidya, and D. K. Pradhan, "Improving Performance of TCP over Wireless Networks," in Proc. 17th International Conf. on Distributed Computing Systems (ICDCS), Baltimore, May 1997.

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B. S. Bakshi, P. Krishna, N. H. Vaidya, and D. K. Pradhan, "Improving performance of TCP over wireless networks," in Proceedings of the 17th International Conference on Distributed Computing Systems, May 1997, pp. 365--373.

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B. Bakshi, P. Krishna, N. H. Vaidya, and D. K. Pradhan, "Improving performance of TCP over wireless networks," in Proc. 17th International Conference on Distributed Computing Systems (ICDCS-17), May 1997.

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B. Bakshi, P. Krishna, N. H. Vaidya, and D. K. Pradhan. Improving performance of TCP over wireless networks. In Proc. of the 17th International Conference on Distributed Computing Systems, May 1997.

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B. Bakshi and P. Krishna and N. Vaidya and D. Pradham, "Improving Performance of TCP over Wireless Networks", 17th International Conference on Distributed Computing Systems (ICDCS), May 1997.

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B. S. Bakshi, P. Krishna, N. H. Vaidya, and D. K. Pradhan, "Improving performance of TCP over wireless networks," in International Conference on Distributed Computing Systems, 1997.

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B. Bakshi, P. Krishna, N. Vaidya, and D. Pradhan, "Improving performance of TCP over wireless networks," in Proceedings of 17th Int. Conf. on Distributed Computing Systems, pp. 693--708, May 1997.

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B. Bakshi, P. Krishna, N. H. Vaidya, and D. K. Pradhan, \Improving Performance of TCP over Wireless Networks," in Proc. ICDCS, Baltimore, may 1997.

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