Using cross-layer information to improve TCP performance with vertical handoffs

Daniel, Laila; Kojo, Markku

doi:10.1109/accessnets.2007.4447135

Cited by 9 publications

(8 citation statements)

References 16 publications

(21 reference statements)

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“…For example the handover notification in [5] relies on Media Independent Handover functions [12], and [6] uses Mobile IP style router advertisements for the detection of the handover at the receiver, but the network layer method is intrinsically slower than lower layer solutions. Indeed, signal strength [3] [11] [4] and link state information [8] [9] from the link layer and below are the most commonly used methods to detect a handover. In our mobility enhancement, we also follow this approach for handover detection.…”

Section: Problem Analysis and Related Workmentioning

confidence: 99%

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TCP Mobility Enhancement for Vertical Handovers

Li²,

2013

2013 4th International Conference on Intelligent Systems, Modelling and Simulation

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TCP is not designed to be used in a wireless mobile environment. It lacks the capability to handle issues caused by handover, especially those between heterogeneous networks. In this paper a mobility enhancement is proposed for TCP to handle these mobility issues. This enhancement does not change the behaviour of TCP in all normal situations and is only evoked when a vertical handover actually occurs. A series of adaptation actions are defined to guide the handed-over TCP flow through phases of handover detection, new network probing, loss recovery and the final state adjustment, so that the flow can adequately settle down in the new network without the aforementioned penalties. The enhancement can handle various vertical handover scenarios and the overall improvement over the original TCP is clearly proven by simulation results.

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Section: Problem Analysis and Related Workmentioning

confidence: 99%

“…3) We can just reset the RTO timer and construct a new one explicitly for the new path to replace it. This idea is used in [8] and [10], and will also be used in our mobility enhancement. This approach is fast and effective, but requires accurate timing for the resetting of the timer.…”

Section: Problem Analysis and Related Workmentioning

confidence: 99%

TCP Mobility Enhancement for Vertical Handovers

Li²,

2013

2013 4th International Conference on Intelligent Systems, Modelling and Simulation

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“…His idea based on delivering the access link characteristic information (LCI) using mobility signaling which has been proposed within the IETF. Daniel proposed enhancements to the TCP sender algorithm to improve TCP performance in the presence of vertical handoffs [39]. The algorithms are assisted with explicit cross-layer notifications about the changes in the access link characteristics.…”

Section: Utilization Of Link Characteristic Informationmentioning

confidence: 99%

Web Acceleration in Asymmetrical Mobile Network

Chen

Wang

Wei

2009

Wireless Pers Commun

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End to end performance of web application degrades seriously in mobile networks because the inefficiencies of HTTP and TCP in lossy and asymmetrical environment. In this article, we discussed common architecture of web accelerator which embraces both HTTP and TCP optimization. Based on the feasibility analyses of various acceleration technologies in asymmetrical mobile network, the components of accelerator and their functions are provided. In order to explain how to choose function entities of accelerator and how to optimize their parameters in asymmetrical environment, we carried out three simulation based analyses. Firstly we characterize the correlations between user perceived web response time and asymmetrical link characteristics. Consequently, we show how HTTP compression strongly affects the web response time when uplink resources are limited. At the same time, our study demonstrated that caching scheme performs poorly when uplink quality degraded. In addition, possible potential methods for web response time and their design criteria are discussed.

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“…The idea is further developed in [3], where quickstart is used to negotiate the correct sending rate with traversing routers after the handover. For the problem of spurious retransmit timeout (RTO), [1], [2], [4] stop the retransmit timer or set it to a very large value during the handover, while [7], [8], [11] try to obtain the correct round-trip-time (RTT) estimation first and compute a new RTO based on it.…”

Section: Related Workmentioning

confidence: 99%

“…A lot more effort is put into adapting the TCP congestion window cwnd to match the BDP of the new path after a vertical handover [4]- [7], [9], [10], [12]. Most of these techniques are based on a prior knowledge or estimation of the new path and feed the information back to the TCP sender to guide the adaptation, although the exact information and adaptation procedure may differ.…”

Section: Related Workmentioning

confidence: 99%

A fast adaptation mechanism for TCP vertical handover

Sleurs

Lil

et al. 2008

2008 International Conference on Advanced Technologies for Communications

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Abstract-In this paper we propose a vertical handover mechanism for TCP to deal with the delay and bandwidth change during the handover. The proposed mechanism relies on the interaction between the sender and the receiver during the handover and requires no a prior information of the new path. The adaptation is triggered by a handover notification at the receiver and finishes in about two round-trip time. Furthermore, it solves the problem of packet reordering and spurious retransmission timeout as well which are also common during vertical handovers. Simulation results show that our mechanism improves TCP performance in various vertical handover scenarios.Index Terms-TCP, Handover, Congestion Control, Mobility.I. INTRODUCTION It is well-known that TCP does not perform well during a handover. A first reason is the possible packet loss during the outage time when the mobile node changes its network connection. Since TCP regards all packet loss as indication of congestion, it will back-off its sending rate unnecessarily. This problem can be readily solved in the network layer with lossless handover techniques such as buffer-and-forward and make-before-break. Unfortunately, this is not the end of problems. When the handover takes place between different type of networks, or in other words, when TCP experiences a vertical handover, the abrupt change in network delay and bandwidth will still affect its performance.When the new path has a higher bandwidth or a lower delay, packets following the new path may overtake those in the old one and arrive at the receiver earlier. Consecutive out-oforder packets can generate enough duplicate ACKs to trigger false fast retransmission while no packet is really lost. On the other hand, when the new path has a lower bandwidth or a higher delay, packets following the new path may not be acknowledged in time, which causes premature RTOs at the TCP sender. All these wrongly triggered congestion responses not only cause unnecessary packet retransmission but also greatly decrease the TCP throughput regardless of the real network conditions. Furthermore, since TCP does not control the sending rate directly but only the number of in-flight packets using a sliding-window based mechanism, it will try to keep the same amount of packets in the network also after a handover. If the Bandwidth-Delay Product (BDP) is changed during a handover -which is very likely the case for a vertical one -TCP will either overrun or under-utilize the capacity of the new path. Because the Additive-Increase MultiplicativeDecrease (AIMD) scheme used in TCP for window adjusting

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Using cross-layer information to improve TCP performance with vertical handoffs

Cited by 9 publications

References 16 publications

TCP Mobility Enhancement for Vertical Handovers

TCP Mobility Enhancement for Vertical Handovers

Web Acceleration in Asymmetrical Mobile Network

A fast adaptation mechanism for TCP vertical handover

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