Performance Enhancement of TCP in Mobile IP Based Networks (original) (raw)
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Improving TCP Performance by Packet Buffering in Mobile IP Based Networks
2004
It is well-known that TCP often experiences severe performance degradation in mobile networks since due to host mobility, packet losses not related to network congestion occur frequently. In this paper, we propose a buffering of packets at a base station to resolve such a problem. Our method can be used without sacrificing the scalability in Mobile IP based networks. For this purpose, we first investigate the performance of TCP without considering packet buffering through simulation experiments. Our results show that in most cases, the smooth handoff by the route optimization extension of the Mobile IP standard cannot prevent degradation of TCP performance in evens of handoffs, although it was originally intended to reduce the number of packets dropped during the handoff. It is also shown that in utilizing the route optimization extension, the TCP performance sometimes becomes worse even than the case of the base Mobile IP, if its smooth handoff fails to avoid losses of four or more packets during the handoff. Such results indicate that for TCP, the smooth handoff is not useful unless the route optimization extension supports a buffering method, which makes handoffs be transparent to transport layer protocols by recovering lost packets during the handoff. We next investigate the impacts of packet buffering on TCP performance. We modify the route optimization extension in order to support packet buffering at the base station, which only requires minor changes. Finally, we discuss some problems occurring when recovering the packets dropped during the handoff by the buffering method, and propose our solution.
Performance improvement by packet buffering in mobile IP based networks
2000
It is well-known that TCP often experiences severe performance degradation in mobile networks since packet losses not related to network congestion occur frequently due to host mobility. In this paper, we propose a new packet buffering method to address such a problem without the scalability problem in Mobile IP based networks. For this purpose, we first investigate the performance of TCP Tahoe without considering packet buffering through the simulation. Our simulation result shows that in most cases, the smooth handoff by the route optimization extension of Mobile IP standard cannot prevent the degradation of TCP performance due to handoffs, although it is designed to reduce the number of packets dropped during the handoff. It also shows that in utilizing the route optimization extension, the TCP performance sometimes becomes worse even than the case of the base Mobile IP unless its smooth handoff makes less than four packets be dropped during the handoff. Such results mean that at least for TCP, the smooth handoff is not useful unless the route optimization extension supports the buffering method, which makes handoffs be transparent to transport layer protocols by recovering the packets dropped during the handoff. We then investigate the effects of packet buffering on the performance of TCP. We modify the route optimization extension in order to support packet buffering at the base station, but it is a very minor change. Finally, we discuss some problems that should be addressed to recover the packets dropped during the handoff by the buffering method without giving a worse impact on the performance of TCP, and propose our solution to solve those problems.
Computer Communications, 2007
Packet losses during the handoff operation by the route optimization extension of the Mobile IP causes performance degradation at the transmission control protocol (TCP). To prevent such degradation a number of packet buffering based methods have been proposed in the literature. However, as the mobile host user continually changes location and can sometimes move into a congested BS in a new foreign subnetwork, its buffered packets are likely to be dropped at the new BS. This can lead to losses at the TCP connections of the mobile user host in the new subnetwork, as well as at the TCP connections of the new BS which experiences severe performance degradation due to the abrupt increase in congestion by the forwarded burst of packets (i.e., global synchronization). This paper proposes a priority forwarding (PF) scheme designed to significantly improve the performance of the packet buffering methods. The proposed PF scheme does not require any modification to the Mobile IP protocol with route optimization extension. The simulation results show that by using the PF scheme the period of global synchronization at the inter-subnetwork handoff is made shorter due to the reduction in packet droppings in the random early detection (RED) buffer. This improves the TCP performance in wireless networks employing Mobile IP with packet buffering.
Improving performance of TCP over mobile wireless networks
Wireless Networks, 2009
Mobile IP is a network layer protocol for handling mobility of hosts in the Internet. However, mobile IP handoff causes degradation of TCP performance. Hence, there is a need for improving performance of TCP over mobile IP in wireless mobile networks. We propose an approach which handles losses due to both wireless link errors and host mobility. To handle losses due to host mobility, a method for seamless handoff is proposed. Empirical results show that the scheme provides substantial improvement of performance.
Journal of Communications and Networks, 2000
Smooth handoff by the route optimization extension of Mobile IP standard should support packet buffering mechanism at a Base Station (BS) in order to prevent TCP performance degradation due to packet losses in mobile networks environment. But, when the mobile host user moves to a congested BS in a new foreign subnetwork, those buffered packets forwarded by the previous BS are dropped and then causes the degradation of the wireless link utilization in the congested BS due to the increased congestion by those forwarded burst packets. Thus, in this paper, to solve this problem, we propose an Implicit Priority Forwarding (IPF) packet buffering scheme. Simulation results show that the proposed IPF packet buffering scheme increases wireless link utilization without a modification of Mobile IP protocol with route optimization extension and thus, it enhances TCP performance.
2013
TCP is the most common and important transport layer protocol and its performance in the wireless environments is characterized by two path characteristics not normally present in wired environments: packet losses due to corruption and mobility.. In this research, we have used the perfect cellular model to model the wireless packet losses due to mobility and handoff in order to get the real performance of TCP. In this paper, we have investigated the behavior of TCP Tahoe, Reno, New Reno, Sack and Vegas in a Cellular Mobile network and tried to find out the impact mobility and handoff of mobile node on the behavior of these TCP variants and which TCP variant has the best performance among all the TCP variants considered in this research.
Impacts of handoff on TCP performance in mobile wireless computing
1997 IEEE International Conference on Personal Wireless Communications (Cat. No.97TH8338), 1997
The e ects of intermittent disconnections due to host motions on the performance of TCP connections are investigated. Fading and hando due to host motion cause increased delay and packet losses to the active transport layer connection. TCP interprets these as signs of network congestion. As a result, it promptly throttles its transmissions and backo s its timers, leading to slow post-hando recovery of the transmission and long idle time. These cause severe end-to-end throughput degradation and unreasonably long interactive delay for human interaction. In this paper, we present three phenomena observed (long communication pause, slow post-hando recovery, and successive timeouts) which are the main causes for TCP performance degradation in the presence of hando. To alleviate these e ects on TCP, two s c hemes, PROBE and BUFFER+FREEZE, are proposed. PROBE makes TCP aware of mobility and adapts the protocol to the mobile environment. Whereas, BUFFER+FREEZE tries to hide the e ects of motion from TCP by bu ering at the basestation and freezing the action of the TCP source.
On Reducing Throughput Degradation of TCP Connection After Vertical Handover
Mobility management solutions designed for heterogeneous networks can provide seamless handover and service continuity. Thus, ongoing TCP sessions can remain active, even when mobile node handovers from one access network to another. In such seamless handover, packet loss can be avoided but TCP still undergoes through several performances degradation issues due to change of network characteristics. Throughput of a TCP connection is badly affected after vertical handover, because mobility management solutions initiates a new TCP connection or migrates the existing one, in new access network, for service continuity. If a new TCP connection is established, then it starts from slow start phase and gradually moves to a steady state, thus throughput degradation occurs. If the existing connection is migrated then TCP enters into congestion avoidance phase due to packet loss creating throughput degradation. To handle this throughput degradation, variety of solutions has been proposed in the literature. In this paper we have discussed some of these solutions that are based on end-to-end philosophy. A comparison is made on the basis of common metrics.
An Explicit Loss and Handoff Notification Scheme in TCP for Cellular Mobile System
International journal of Computer Networks & Communications, 2016
With the proliferation of mobile and wireless computing devices, the demand for continuous network connectivity exits for various wired-and-wireless integrated networks. Since Transmission Control Protocol (TCP) is the standard network protocol for communication on the Interne, any wireless network with Internet service need to be compatible with TCP. TCP is tuned to perform well in traditional wired networks, where packet losses occur mostly because of congestion. However cellular wireless network suffers from significant losses due to high bit errors and mobile handoff. TCP responds to all losses by invoking congestion control and avoidance algorithms, resulting in degraded end-to-end performance. This paper presents an improved Explicit Loss Notification algorithm to distinguish between packet loss due to congestion and packet loss due to wireless errors and handoffs. Simulation results show that the proposed protocol significantly improves the performance of TCP over cellular wireless network in terms of throughput and congestion window dynamics.
Study of Proposed Methods for Improving TCP Performance Over Wireless Links
Computing Research Repository, 2009
TCP is designed for networks with assumption that major losses occur only due to congestion of network traffic. On a wireless network TCP misinterprets the transmission losses due to bit errors and handoffs as losses caused by congestion, and triggers congestion control mechanisms. Because of its end to end delivery model, congestion handling and avoidance mechanisms, TCP has been widely accepted as Transport layer protocol for internetworks. Extension of Internetworks over wireless links is inevitable with the spread of ubiquitous computing and mobile communications. This paper presents study of different mechanisms proposed to extend Transport Control Protocol and other alternate solutions to enhance end to end performance over lossy wireless links. The paper studies details of different design choices proposed and their technical advantages and disadvantages. Finally, an analysis and proposal for best choice of proposed schemes are made for wireless networks.