TCP Performance Degradation Research Articles

Protocols Amplifying TCP Effects

The TCP protocol's notion is that if a packet is lost due to network congestion, it isn't of much use in wireless networks, because TCP isn't very good at terminating its role in these types of networks. We've detailed and listed the main causes of this performance decline in this article. Although numerous procedures and protocols have yet to be released, throughout the time of identifying these reviews, only a few of them are considered. End-to-end techniques, fragmented connection approaches, and proxy-based approaches are some of the solutions to clarify performance decline in wireless networks. These approaches are likely to yield a short action, but a number of issues remain unsolved, so this text is used to simply identify the most likely cause of TCP performance degradation in wireless networks and to investigate some new methods for various TCP to predict TCP rationale in wireless and WLAN networks

Analysis of Congestion using mobile nodes in Wireless Network

This article discusses the work plan of wireless ad hoc network and the problems related to it during congestion. The congestion in wireless network congestion will vary with different topologies, methods of network deployment, mobility, channel utilization and power consumption at node level. This might lead to degradation of TCP performance of packet loss. In this research the proposed work plan the use of different number of nodes and their effect on congestion in wireless network. The reason for loss in wireless network could be overload of packets in node buffer space. This research will also enable us to conduct a deeper study to understand network congestion in ad-hoc networks. We will try to simulate various network environments with different number of users and then study the network on parameters like throughput, good put; packets dropped etc.

DL-TCP: Deep Learning-Based Transmission Control Protocol for Disaster 5G mmWave Networks

The 5G mobile communication system is attracting attention as one of the most suitable communication models for broadcasting and managing disaster situations, owing to its large capacity and low latency. High-quality videos taken by a drone, which is an embedded IoT device for shooting in a disaster environment, play an important role in managing the disaster. However, the 5G mmWave frequency band is susceptible to obstacles and has beam misalignment problems, severing the connection and greatly affecting the degradation of TCP performance. This problem becomes even more serious in high-mobility drones and disaster sites with many obstacles. To solve this problem, we propose a deep-learning-based TCP (DL-TCP) for a disaster 5G mmWave network. DL-TCP learns the node's mobility information and signal strength, and adjusts the TCP congestion window by predicting when the network is disconnected and reconnected. As a result of the experiment, DL-TCP provides better network stability and higher network throughput than the existing TCP NewReno, TCP Cubic, and TCP BBR.

T-DLRP: Detection of Fast Retransmission Losses Using TCP Timestamp for Improving the End-to-End Performance of TCP over Wireless Networks

Improving the end-to-end performance of TCP over wireless networks has been an active research area. When TCP operates in wireless networks, the performance of TCP degrades significantly. It is well known that frequent retransmission timeouts are the leading source of TCP performance degradation over wireless networks. Retransmission timeouts are unavoidable, when the fast retransmission of a lost packet fails to reach the destination. There have been many schemes developed for reducing the retransmission timeouts of TCP. However, these schemes have no mechanism to detect the loss of fast retransmitted packets over wireless networks. In this paper, we introduce an efficient TCP mechanism, called T-DLRP, which is able to detect the loss of fast retransmitted packets and react accordingly. To justify our contributions, we compared T-DLRP against TCP New Reno, Vegas, New Jersey, Veno, Cerl, and DAC via extensive simulations using Qualnet 4.5 simulator. The results demonstrate that our mechanism achieves significant improvement over existing TCP variants especially in a coexisted network with packet loss and fast retransmission losses. Compared to DAC, T-DLRP gains more than 70% improvement in terms of accuracy over wireless networks. Also, our experiments of multiple connections of the same TCP flows reveal that T-DLRP has better fairness compared to TCP NewReno.

A Non-Convex Distributed Optimization Framework and its Application to Wireless Ad-hoc Networks

The continuously increasing demand for resources in modern, both wired and wireless, communication networks urges for more efficient resource allocation. Such an allocation of resources to network users can be formulated as an optimization problem. Traditional resource allocation protocols, such as TCP, operate inefficiently in cases that there is competition for resources by multimedia applications and some, or possibly all, links in the network are wireless. In this paper, the performance degradation of TCP in modern networks is quantified to highlight the necessity for a novel optimization-based resource allocation protocol. To this direction, a new optimization framework is presented that can provide the theoretical foundations of such a protocol by proving a sufficient, and in some cases also necessary, condition for distributed solution of non-convex problems. The wide applicability of this general framework is illustrated by considering a resource allocation formulation in TDMA/CDMA ad-hoc networks. The convergence properties to the optimal solution are first identified and a distributed algorithm is proposed. Moreover, a novel heuristic is developed to approximate the optimal solution when the condition does not hold and resolve network oscillations. Finally, the performance of the proposed methodology is evaluated and compared against other approaches in literature by simulation.

Fat-Tree에서 링크 장애가 패킷분산방식의 성능에 미치는 영향

Most of recent studies on data center networks are based on the assumption of symmetrical multi-rooted tree topologies such as a Fat-Tree. While packet scatter schemes are very effective for such a network topology, it is known that various failures can result in an asymmetric topology which degrades TCP performance. In this paper, we reexamine the effects of link failures on packet scatter schemes in Fat-Trees. Our simulation results show that in case of a single link failure in a large-scale Fat-Tree, packet reordering does not occur enough to degrade TCP performance. This implies that we do not necessarily need a complex scheme to make packet schemes robust to link failures.

A study of TCP performance in wireless environment using fixed-point approximation

Loss of IP packets occurring as a result of imperfect local error correction is one of the major reasons for TCP performance degradation in wireless networks. These losses are misinterpreted by TCP senders as congestion indications and subsequently lead to the sharp decrease of the sending rate. In addition to wireless losses, packets can be lost as a result of buffer overflows at the IP layer. To study performance experienced by TCP sessions sharing a wireless channel, we adopt the fixed-point approximation. We distinguish between two modes of operation: (i) packet losses are mainly caused by imperfect error correction, (ii) the packet loss process is dominated by the buffer overflow. Applying different TCP models for these two regimes we approximate TCP throughput as a function of underlying layers’ parameters. Using this approach we study the effect of various protocol parameters on TCP throughput. We also investigate the effect of the queuing system involved in our analysis and demonstrate that usage of complex models with correlated arrival processes and generally distributed service time does not qualitatively affect the estimated TCP throughput. This observation allows to use simple queuing models having closed form solutions for performance metrics of interest, e.g. M/M/1/K or Geo/Geo/1/K. Finally, we address the question of choosing appropriate queuing model for quantitative TCP analysis.

TCP over optical burst-switched networks with controlled burst retransmission

For optical burst-switched (OBS) networks in which TCP is implemented at a higher layer, the loss of bursts can lead to serious degradation of TCP performance. Due to the bufferless nature of OBS, random burst losses may occur, even at low traffic loads. Consequently, these random burst losses may be mistakenly interpreted by the TCP layer as congestion in the network. The TCP sender will then trigger congestion control mechanisms, thereby reducing TCP throughput unnecessarily. In this paper, we introduce a controlled retransmission scheme in which the bursts lost due to contention in the OBS network are retransmitted at the OBS layer. The OBS retransmission scheme can reduce the burst loss probability in the OBS core network. Also, the OBS retransmission scheme can reduce the probability that the TCP layer falsely detects congestion, thereby improving the TCP throughput. We develop an analytical model for evaluating the burst loss probability in an OBS network that uses a retransmission scheme, and we also analyze TCP throughput when the OBS layer implements burst retransmission. We develop a simulation model to validate the analytical results. Simulation and analytical results show that an OBS layer with controlled burst retransmission provides up to two to three orders of magnitude improvement in TCP throughput over an OBS layer without burst retransmission. This significant improvement is primarily because the TCP layer triggers fewer time-outs when the OBS retransmission scheme is used.

Improving TCP performance with fast adaptive congestion control during soft vertical handoff

Recently, the research on the interworking between 3G cellular networks and WLANs is actively being constructed. To integrate these two technologies, there are many issues such as the network architecture, mobility management, and security which should be solved. During vertical handoff, some undesirable phenomena may mistakenly trigger TCP congestion control operations and thus degrade TCP performance. In this paper, we propose an approach that can quickly estimate available bandwidth when a mobile node (MN) handoff occurs. A sender updates the adaptive slow-start threshold (ssthresh) and congestion window size (cwnd) to improve TCP performance during soft vertical handoff in hybrid mobile networks. Our scheme requires only minor modifications of the transport layer of the end hosts. Simulation results show that our scheme effectively improves the TCP performance.

무선 환경에서 TCP 스퓨리어스 타임아웃 방지를 위한 SR-ARQ 재전송 지속성 관리 방안

To detect and recover packet losses over wireless links is very important in terms of reliability in packet transmission. Most wireless communication systems adopt an automatic repeat request (ARQ) protocol operating at link layer. However, it has been constantly addressed that the interaction not harmonized sufficiently between ARQ and TCP rather degrades TCP performance. In this paper, therefore, we propose an improved scheme from the aspect of the interaction with TCP loss recovery mechanism that can be applied to selective repeat ARQ (SR-ARQ) protocol and prove that the proposed scheme improves TCP performance significantly by OPNET simulations.

TCP CAE: an improved congestion control using comparative ACK-based estimator

TCP receivers deliver ACK packets to senders for reliable end-to-end transfer. However, due to network congestion in the backward direction, ACK packets may not be successfully transferred, which causes the degradation of TCP performance. To overcome this problem, this paper proposes a reverse congestion warning mechanism and a congestion handling mechanism in heterogeneous networks with heavy background traffic in the backward direction. In the proposed scheme, senders detect the reverse direction congestion and execute an exponential backoff algorithm in advance instead of waiting for RTO expiration. According to the simulation results using the NS-2 network simulator, the proposed scheme shows a performance elevation of 20% than Reno, 150% than New Reno, and 450% than Westwood, respectively, under heterogeneous networks and that the error rate of the radio link is 1% when the backward network is congested.

Cross-Layer Explicit Link Status Notification to Improve TCP Performance in Wireless Networks

To alleviate the performance degradation of conventional TCP in wireless networks, many schemes have been proposed so far. One category of such schemes is the Explicit Loss Notification (ELN) scheme in which TCP senders are notified of wireless losses so as to avoid congestion control against those losses. Thus the key design factor of the ELN scheme is how to detect wireless losses accurately and rapidly. This paper proposes a new ELN scheme, in which wireless losses are detected by monitoring the operation of the wireless link layer. By exploiting such cross-layer design, the proposed scheme can detect wireless losses without additional transmission over the wireless link and thus achieves accurate detection with minimum delay. The proposed scheme additionally sends new information, that is, Explicit Retransmission Start Notification, in order to prevent spurious timeouts of the TCP senders. Furthermore, in order to handle packet reordering and avoid successive shrinking of a congestion window due to multiple packet drops, a new TCP modification is proposed. Through intensive simulations, it is demonstrated that the proposed scheme outperforms the other ELN schemes, and yields the throughput performance of more than 400% of TCP-Reno and 150% of Snoop in the considered environments.

Packet Sampling TCP Flow Rate Estimation and Performance Degradation Detection Method

Managing the performance at the flow level through traffic measurement is crucial for effective network management. With the rapid rise in link speeds, collecting all packets has become difficult, so packet sampling has been attracting attention as a scalable means of measuring flow statistics. In this paper, we firstly propose a method of estimating TCP flow rates of sampled flows through packet sampling, and then develop a method of detecting performance degradation at the TCP flow level from the estimated flow rates. In the method of estimating flow rates, we use sequence numbers of sampled packets, which make it possible to improve markedly the accuracy of estimating the flow rates of sampled flows. Using both an analytical model and measurement data, we show that this method gives accurate estimations. We also show that, by observing the estimated rates of sampled flows, we can detect TCP performance degradation. The method of detecting performance degradation is based on the following two findings: (i) sampled flows tend to have high flow-rates and (ii) when a link becomes congested, the performance of high-rate flows becomes degraded first. These characteristics indicate that sampled flows are sensitive to congestion, so we can detect performance degradation of flows that are sensitive to congestion by observing the rate of sampled flows. We also show the effectiveness of our method using measurement data.

A Novel AQM Scheme for Wireless Networks with BER Estimation

A novel active queue management(AQM) scheme is proposed to deal with the performance degradation of TCP in wireless scenario. One of the key sources causing performance degradation is the high bit error rate(BER), which is an intrinsic link characteristic of wireless network. A high-gain observer is constructed to estimate the effect of bit error of source data. With the estimated BER, the drop probability of queuing packets can be adapted to time-varying link conditions and network loads so that it reduces the queue oscillation and maintains good throughput. Simulation results show that the proposed scheme outperforms RED(Random Early Detection) algorithm with strong robustness to time-varying scenarios of wireless networks.

Improving performance of TCP over mobile wireless networks

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.

Adding network-layer intelligence to mobile receivers for solving spurious TCP timeout during vertical handoff

With the help of mobile IP/IPv6 and soft handoff, ongoing TCP sessions can remain active and handoff packet loss can be avoided. However, TCP still faces several performance degradation issues due to the disparities in bandwidth and propagation delay between different access networks. Particularly, during vertical handoffs, some undesirable phenomena may erroneously trigger TCP congestion-control actions and thus degrade TCP performance. In this article we tackle the spurious timeout problem frequently associated with handovers from fast to slow links. We propose three network-layer schemes: fast ACK, slow ACK, and ACK delaying. These schemes require only minor modifications to the network layer of mobile receivers and no change to the TCP protocol and the TCP sender. The simulation results show that these schemes can effectively improve TCP performance during soft vertical handoffs

네트워크 이동 환경에서의 TCP 성능 향상 기법

인터넷과 이동 네트워크로 구성된 유무선 통합 네트워크에서는 인터넷 상의 송신자와 이동 네트워크 상의 이동 호스트(MH, Mobile Host) 간 경로는 두 개 이상의 무선링크로 구성된다. 이와 같은 네트워크 이동 환경에서 TCP의 종단간 제어 특성을 유지하면서 무선링크에서의 패킷 전송 오류로 인한 TCP의 성능 저하를 극복하는 방안을 제안한다. 제안하는 방안에서는 수신된 패킷의 시퀀스 번호와 ACK 번호를 근거로 하여 무선링크 상에서의 전송 오류로 인한 패킷 손실 정보를 추출하고 이 정보를 상류의 라우터에게 전달함으로써 상류의 액세스 라우터나 이동 라우터에서 신속히 손실된 패킷을 재전송할 수 있도록 한다. 제안하는 방안은 상류 무선링크에서의 패킷전송 오류를 신속히 극복하는 특성을 가지며 모의실험을 통하여 제안한 방안의 TCP 전송률 성능을 평가하였다. TCP 종단간 제어 특성을 가지며 송신자나 수신자 측에 추가 기능이 요구되지 않는 snoop 방식과 비교할 때 제안하는 방안의 TCP 성능이 크게 개선됨을 모의실험을 통해 확인하였다. In the integrated wired/wireless network which consists of the Internet and moving networks, multiple wireless links are used to connect a fixed host(FH) in the Internet to a mobile host(MH) in the moving network. For use in such an environment, we propose a scheme to overcome the TCP performance degradation due to the packet losses over the wireless links without losing the end-to-end TCP semantics. The proposed scheme in each mobile router(MR) allows to obtain the information regarding packet losses over the upstream wireless links based on the received packet sequence number and the ACK number. This information is delivered to the upstream router, which enables the upstream access router(AR) or MR to quickly retransmit the lost packets. The proposed scheme has the feature to quickly recover the packet losses incurred over the upstream wireless links and the performance of the proposed scheme is evaluated through simulation. It is shown that the significant performance gain can be obtained using the proposed scheme compared with the snoop mechanism which maintains end-to-end TCP semantics and does not require any additional features at the source and/or destination nodes.

Snug-Vegas and Snug-Reno: efficient mechanisms for performance improvement of TCP over heterogeneous networks

Improving the performance of the traditional TCP in wireless IP communications has been an active research area. The significant cause of packet losses in such heterogenous networks is no longer limited to network congestion. The performance degradation of TCP in wireless and wired-wireless hybrid networks is mainly due to its lack of ability to differentiate the packet losses caused by network congestions from the losses caused by wireless link errors. New variants of TCP Vegas and TCP Reno named Snug-Vegas and Snug-Reno, respectively, are proposed. By using random-loss indications marked by base stations, Snug-Vegas and Snug-Reno may detect random packet losses precisely. Through the packet loss differentiation, Snug-Vegas and Snug-Reno react appropriately to the losses, and based on the simulation results, it is seen that the throughput of connection over heterogeneous networks can be significantly improved.

Detection of TCP Performance Degradation Using Link Utilization Statistics

In this paper, we propose a method of detecting TCP performance degradation using only bottleneck-link utilization statistics: mean and variance. The variance of link utilization normally increases as the mean link-utilization increases. However, because link-utilization has a maximum of 100%, as the mean approaches 100%, the possible range of fluctuation becomes narrow and the variance decreases to zero. In this paper, using the M/G/R processor sharing model, we relate this phenomenon to the behavior of flows. We also show that by using this relationship, we can detect TCP performance degradation using the mean and variance of link utilization. In particular, this method enables a network operator to determine whether or not the degradation originates from the congestion of his/her own network. Because our method requires us to measure only link utilization, the cost of performance management can be greatly decreased compared with the conventional method, which requires dedicated functions for directly measuring the TCP performance.

TCP Issues in Mobile Ad Hoc Networks: Challenges and Solutions

Mobile ad hoc networks (MANETs) are a kind of very complex distributed communication systems with wireless mobile nodes that can be freely and dynamically self-organized into arbitrary and temporary network topologies. MANETs inherit several limitations of wireless networks, meanwhile make new challenges arising from the specificity of MANETs, such as route failures, hidden terminals and exposed terminals. When TCP is applied in a MANET environment, a number of tough problems have to be dealt with. In this paper, a comprehensive survey on this dynamic field is given. Specifically, for the first time all factors impairing TCP performance are identified based on network protocol hierarchy, i.e., lossy wireless channel at the physical layer; excessive contention and unfair access at the MAC layer; frail routing protocol at the network layer, the MAC layer and the network layer related mobile node; unfit congestion window size at the transport layer and the transport layer related asymmetric path. How these factors degrade TCP performance is clearly explained. Then, based on how to alleviate the impact of each of these factors listed above, the existing solutions are collected as comprehensively as possible and classified into a number of categories, and their advantages and limitations are discussed. Based on the limitations of these solutions, a set of open problems for designing more robust solutions is suggested.