Performance improvements for TCP in mobile networks with high packet delay variations

Schüler, Jörg; Gruhl, S.; Schwabe, T.; Schweigel, Mathias

doi:10.1016/s1388-3437(01)80148-7

Cited by 3 publications

(5 citation statements)

References 12 publications

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“…Thus, a TCP-friendly system design should avoid such delay spikes. If this is not feasible, one might think about optimization techniques such as transport layer protocol helpers [7,8] or TCP enhancements like the Eifel-Algorithm [5].…”

Section: Discussionmentioning

confidence: 99%

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The Sensitivity of TCP to Sudden Delay Variations in Mobile Networks

Scharf

Necker

Gloss

2004

Lecture Notes in Computer Science

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Abstract. This paper studies the impact of variable transmission delays on the Transmission Control Protocol (TCP). Sudden delay variations, which are not unemurnon in mobile networks, may degrade the performance since they may cause spurious TCP timeouts. The rnost irnportant pararneter in this context is the TCP retransmission timer. In this paper, we analyze TCP's round-trip time estimation for bulk data traffic over wireless links. The rnain contribution is a new analytical rnodel that accurately predicts the timeout duration from given network pararneters. As a first result, the rnodel shows that the round-trip time sampling rate has a significant impact on the timer characteristics. Therefore, the standardized estimation algorithm does not harmonize weil with timestamp-based rneasurement. Second, we quantify the risk of spurious TCP timeouts triggered by changing round-trip tirnes, in particular long off periods. We conclude that delay variations are only critical when they are on the order of seconds.

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Section: Discussionmentioning

confidence: 99%

“…As a consequence, TCP may waste scarce bandwidth or underutilize the available resources. Both effects have already been studied extensively [5,6,7,8,9,10].…”

mentioning

confidence: 99%

The Sensitivity of TCP to Sudden Delay Variations in Mobile Networks

Scharf

Necker

Gloss

2004

Lecture Notes in Computer Science

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“…Protocol helpers have also been proposed to improve TCP performance in the presence of spurious timeouts, either by filtering redundant segments [10], by buffering of acknowledgments [11] or by manipulating the receiver advertised window [12]. However, none of these approaches can mitigate problems caused by high bandwidth delay products.…”

Section: Protocol Helpersmentioning

confidence: 99%

Performance of Different Proxy Concepts in UMTS Networks

Necker

Scharf

Weber

2005

Wireless Systems and Mobility in Next Generation Internet

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It is well known that the large round trip time and the highly variable delay in a cellular network may degrade the performance of TCP. Many concepts have been proposed to improve this situation, including performance enhancing proxies (PEPs). One important class of PEPs are split connection proxies, which terminate a connection from a server in the Internet in a host close to the Radio Access Network (RAN) and establish a second connection towards the mobile User Equipment (UE). This connection splitting can be done either purely on the transport layer (TCP proxy) or on the application layer (HTTP proxy in the case of web traffic). While it is clear that an application layer proxy also infers the splitting of an underlying transport layer connection, the performance of applications may be essentially different for both approaches. In this paper, we first study the general impact of a split connection proxy on TCP bulk data transfer. We then focus on the case of web traffic and investigate the TCP connection behavior of the Mozilla web browser. Based on this, we study the performance of TCP and HTTP proxies in UMTS networks under different scenarios and for different HTTP configurations.

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“…Nevertheless, in most of the investigated cases it still improves the performance by avoiding retransmission timeouts. Also, the duplicate packets could be filtered at the Access Point with the Spurious Packet Filter (SPF) introduced in [9], saving scarce wireless link resources and enabling TCP to recover faster. On the other hand, the effects of packet-re-ordering could he minimized by fast packet forwarding, prioritized queuing or an improved TCP delayed acknowledgment strategy.…”

Section: Resultsmentioning

confidence: 99%

“…The influence ofunusual packet delays has been studied in [9]. For the investigations the network simulator ns was used with its implementations for hlobile IPv4 and the TCP versions Tahoe, Reno, NewReno and SACK [IO].…”

Section: Hand-off Scenariomentioning

confidence: 99%