Transmission Control Protocol Congestion Control Mechanism Research Articles

Improving the TCP Newreno Congestion Avoidance Algorithm on 5G Networks

Enhancing Transmission Control Protocol (TCP) performance is one of the key solutions for improving the performance of modern wireless communication networks. It is a highly dependable protocol for communication between network hosts based on an internet protocol (IP). It uses packet sequence numbering and acknowledgment (ACK) packets to ensure that data is recoverable in the event of problems like data loss, and corruption. Loss-based Congestion Control (CC) algorithms overreact and underperform in the presence of rapid channel oscillations, resulting in buffer bloat and significant delays. The goal of this paper is to develop an efficient congestion control mechanism for the new TCP agent Newreno over the fifth generation (5G) network, as well as to improve the increment and decrement strategy for adjusting the congestion window (cwnd) during the congestion avoidance phase, It also fast adapts to the current network requirements and adjusts the transmission rate accordingly. TCP enhancements can improve performance under dynamic traffic loads and over long product channels with high bandwidth. As a result, when such a TCP congestion control mechanism is improved, the network’s throughput increases, and low packet losses, and delay are reduced.

Introducing a New TCP Variant for UAV networks following comparative simulations

The Transmission Control Protocol (TCP) is a reliable, connection oriented, congestion control mechanism, currently utilized the majority of both wired and wireless networks at the transport layer. An important function of TCP is the network congestion control mechanism; it governs the packet transmission rate and us enables the protocol to respond to congestion signals. Considering the wide spectrum of requirements stemming from unique network and channel characteristics, there exist numerous variants of TCP. While is commonly utilized in applications requiring reliable and ordered reception of packets, the standard TCP congestion control mechanism demonstrates poor performance in high-mobility wireless networking scenarios, as high mobility implies unreliable radio links and consecutive re-transmissions. In this paper we performed a comparative analysis of a spectrum of TCP variants, with the ultimate goal of deriving best practices to support real-time, yet reliable communication in high-mobility scenarios, with a special focus on aerial mobile ad hoc networks composed of Unmanned Aerial Vehicles (UAVs). Following the findings of this simulation evaluation, we introduce a new TCP variant for Flying Ad hoc Networks (FANETs), named Swarm HTCP (S-HTCP), which is shown to outperform the other variants in such network conditions.

Throughput Analysis for TCP Over the FSO-Based Satellite-Assisted Internet of Vehicles

Free-space optics (FSO)-based, low-earth orbit (LEO) satellite-assisted Internet of vehicles (IoVs) has recently attracted research efforts worldwide. For the majority of Internet applications, transmission control protocol (TCP) is one of the most widely deployed protocols. Nevertheless, a complete understanding of the TCP performance over FSO-based satellite-assisted IoVs networks is still lacking in the literature. This is a highly challenging issue, as a consequence of the non-trivial interdependencies between transmission losses caused by the dynamics/uncertainty of atmospheric last-mile channels and the buffer overflows on the Internet, as well as their joint impact on the TCP congestion control mechanisms. This paper offers a comprehensive analytical framework that allows assessing the TCP throughput performance under the joint impact of congestion losses occurred in the Internet and transmission errors at the last-mile link from the satellite-to-vehicle. Internet access for emerging unmanned aerial vehicles (UAVs) is considered while the analysis can be also applied to other kinds of vehicles, which, in fact, require simpler channel models. The link-layer incremental redundancy hybrid automatic repeat request (IR-HARQ) protocol is employed at satellite-to-UAV channels to further improve the TCP throughput performance. Numerical results provide non-trivial findings and insights for the TCP performance in satellite/FSO-based IoVs, in which optimal UAV’s parameters are chosen to maximize the TCP throughput.

A Comprehensive Overview of TCP Congestion Control in 5G Networks: Research Challenges and Future Perspectives.

In today’s data networks, the main protocol used to ensure reliable communications is the transmission control protocol (TCP). The TCP performance is largely determined by the used congestion control (CC) algorithm. TCP CC algorithms have evolved over the past three decades and a large number of CC algorithm variations have been developed to accommodate various network environments. The fifth-generation (5G) mobile network presents a new challenge for the implementation of the TCP CC mechanism, since networks will operate in environments with huge user device density and vast traffic flows. In contrast to the pre-5G networks that operate in the sub-6 GHz bands, the implementation of TCP CC algorithms in 5G mmWave communications will be further compromised with high variations in channel quality and susceptibility to blockages due to high penetration losses and atmospheric absorptions. These challenges will be particularly present in environments such as sensor networks and Internet of Things (IoT) applications. To alleviate these challenges, this paper provides an overview of the most popular single-flow and multy-flow TCP CC algorithms used in pre-5G networks. The related work on the previous examinations of TCP CC algorithm performance in 5G networks is further presented. A possible implementation of TCP CC algorithms is thoroughly analysed with respect to the specificities of 5G networks, such as the usage of high frequencies in the mmWave spectrum, the frequent horizontal and vertical handovers, the implementation of the 5G core network, the usage of beamforming and data buffering, the exploitation of edge computing, and the constantly transmitted always-on signals. Moreover, the capabilities of machine learning technique implementations for the improvement of TCPs CC performance have been presented last, with a discussion on future research opportunities that can contribute to the improvement of TCP CC implementation in 5G networks. This survey paper can serve as the basis for the development of novel solutions that will ensure the reliable implementation of TCP CC in different usage scenarios of 5G networks.

Improving Congestion Control of TCP for Constrained IoT Networks.

For smooth integration with middleboxes on the Internet, TCP (Transmission Control Protocol) is favorably considered as a transport-layer protocol for IoT (Internet of Things) networks. In constrained networks, TCP tends to perform well with a small window size. For example, the uIP (micro IP) TCP/IP stack sets the TCP window size to one segment by default. In such a case, managing the retransmission timer is a primary approach to congestion control. In this paper, we examine the congestion control mechanism of TCP in the uIP stack using grid topology networks. In the preliminary test using the Cooja network simulator, the results show that the original uIP TCP causes lots of retransmissions when a radio duty cycling mechanism such as ContikiMAC is used. One main reason is that, once retransmission is deemed to be necessary, the original uIP TCP sets the retransmission timer based on the fixed RTO (retransmission timeout) before performing a retransmission. Since ContikiMAC may cause large RTT (round-trip time) variations due to the hidden terminal problem, the retransmission timer based on the fixed RTO value may cause lots of retransmissions. To address the problem, we propose a new scheme for managing the retransmission timer which adopts the notion of weak RTT estimation of CoCoA, exponential backoffs with variable limits, and dithering. Simulation results show that our proposed scheme reduces retransmissions while enhancing throughput and fairness when an RDC (radio duty cycling) mechanism is used.

A Sustainable Solution to Support Data Security in High Bandwidth Healthcare Remote Locations by Using TCP CUBIC Mechanism

Long distance high bandwidth networks are spanning several continents and many remote Healthcare centers are centralizing their data centers for economic reasons. For the best performance of their data centers, TCP (Transmission Control Protocol) performance and data security are the main critical issues in these network scenarios. TCP performance is directly related to its congestion control mechanism which is responsible for detecting and reacting to the overload traffic on the network. Data security is related to the security mechanism being used by sender and receiver nodes during communication. Linux users, which have rapidly increased in the last five years and most of the Healthcare data centers are being deployed on the Linux operating system, focus the researchers to work on Linux to enhance its performance and security accordingly. The Linux operating system uses TCP CUBIC as a congestion control mechanism with TCP during communication. TCP CUBIC became the default congestion control mechanism of Linux in 2006 after kernel 2.6.18. TCP CUBIC is fundamentally a loss based TCP congestion control mechanism and at each packet loss detection, it reduces its Congestion Window ( $cwnd$ c w n d ) size 20 percent instead of 50 percent as in trademark congestion control mechanism Standard TCP. The aim of this paper is to design a new security mechanism that will work with TCP CUBIC to achieve the maximum possible performance and security over the network link. In this paper, Network Simulator 2 (NS-2) is used to compare the performance of TCP CUBIC with state-of-the-art mechanisms in long and short Round Trip Time (RTT), high bandwidth network scenarios. Results show that when new security mechanism is used with TCP CUBIC, overall better performance in the form of protocol fairness, TCP friendliness, goodput, and convergence time is achieved over the network link.

Channel Occupancy Ratio Based TCP Congestion Control in Adhoc Networks

Wireless Network is been used widely in the recent years due to its low-cost nature. More number of real time applications have been used by varied segments of users across the world. The advancements in the mobile technology have made ad hoc networks as important and active field of communication and networks. Most of the time the network cannot handle the traffic in the network which ultimately affects the Quality of Service (QoS). The conventional Transmission Control Protocol (TCP) cannot handle this huge volume of traffic and control the congestion in the network. This issue in the wireless network is been addressed by various researchers in the world but still the scope and need for improvements are more. This paper analyzes many TCP congestion control mechanisms and proposes an efficient approach for congestion control by estimating Channel Occupancy Ratio (COR). The COR is estimated based on machine learning algorithm which is trained using the historical data extracted from MAC layer. This cross layer based approach is found to be more efficient when compared to other methods proposed in the literature.

Modelling and analysis of TCP congestion control mechanisms using stochastic reward nets

Modelling of congestion control mechanisms of the transmission control protocol (TCP) helps to obtain parametric results that help to better understand the TCP behaviour under different operating conditions. Several analytical models were proposed to analyse the behaviour of TCP congestion control mechanisms. However, most of these models were designed for a few TCP sessions with non-persistent connections. A few analytical studies were presented for modelling persistent TCP connections. Nevertheless, these studies have many limiting assumptions and are not scalable. In this work, a stochastic reward nets model is introduced for the TCP Reno with the persistent TCP connections, which share two bottleneck links in a wide area network. A microscopic approach was used for constructing the proposed model that captures most features of congestion control mechanisms used by the TCP Reno, and interactions between different TCP sessions. The proposed model relaxed several limiting assumptions adopted by other related models introduced in the literature. To validate the proposed model, analytical results are extensively compared with simulation results.

End-to-End Loss Based TCP Congestion Control Mechanism as a Secured Communication Technology for Smart Healthcare Enterprises

Many smart healthcare centers are deploying long distance, high bandwidth networks in their computer network infrastructure and operation. Transmission control protocol (TCP) is responsible for reliable and secure communication of data in these medial infrastructure networks. TCP is reliable and secure due to its congestion control mechanism, which is responsible for detecting and reacting to the congestion in the network. Many TCP congestion control mechanisms have been developed previously for different operating systems. TCP CUBIC, TCP Compound, and TCP Fusion are the default congestion control mechanism in Linux, Microsoft Windows, and Sun Solaris operating systems, respectively. The earliest congestion control mechanism Standard TCP acts as the trademark congestion control mechanism. The exponential growth of congestion window ( $cwnd$ ) in slow start phase of the TCP CUBIC causes burst losses of packets, and TCP flows did not share available link bandwidth fairly. The prime aim of this paper is to enhance the performance of TCP CUBIC for long distance, high bandwidth secured networks to achieve better performance in medical infrastructure, concerning packet loss rate, protocol fairness, and convergence time. In this paper, congestion control module for slow start is proposed, which reduces the effect of the exponential growth of $cwnd$ by designing the new limits of $cwnd$ size in slow start phase, which in turn decreases the packet loss rate in healthcare networks. NS-2 is used to simulate the experiments of enhanced TCP CUBIC and state-of-the-art congestion control mechanisms. Results show that the performance of enhanced TCP CUBIC outperforms by 18% as compared with the state-of-the-art congestion control mechanisms.

End to end delay modeling of heterogeneous traffic flows in software defined 5G networks

In ultra-dense 5th Generation (5G) wireless networks, we believe that foreground User Datagram Protocol (UDP) traffic flow is ′squeezed′ by Transmission Control Protocol (TCP) background because of increasing queue waiting time and extra transmission delay for each timeout in TCP congestion control mechanism. Therefore, traffic Heterogeneity which is defined by the rate between number of UDP over TCP traffic flows for each forwarding device, has become more significant. According to the 3rd Generation Partnership Project (3GPP) Release 13, conventional Long Term Evolution - Self Organize Networks (LTE-SON) does not consider Heterogeneity rate of traffic flows while balancing load between neighbor eNodeBs (eNBs). In order to reduce end to end delay (e2eDelay) of foreground TCP traffic flow, an optimal path should be selected by considering both load Intensity and traffic Heterogeneity level of eNBs. To do this, we propose a Software-Defined Networks (SDN)-based softwarization approach brought by 5G networks with three fold contributions: virtualization of topology graph (G), e2eDelay optimization which is run in terms of both load Intensity (ρj(t)) and Heterogeneity rate(Hj(t)), and novel Queuing Theory based OpenFlow (OF) switch model. Moreover, due to being bottleneck, centralized SDN-Controller is proposed to accelerated with novel three heuristics including shortest path and e2eDelay optimization algorithms running in parallel manner. More specifically, this process is combined into a novel closed-form expression of e2eDelay(Ti(t)) in two main parts: Data plane effect and Control plane effect. As a result, proposed SDN-based e2eDelay model serves foreground TCP traffic flow upto 74% and 98% less e2eDelay than LTE-SON and conventional LTE.

Formal modelling of TCP congestion control mechanisms ECN/RED and SAP-LAW in the presence of UDP traffic

Congestion avoidance mechanisms are used to prevent the saturation of the gateway which represents a bottleneck of the system. Recently, a new method for the congestion avoidance has been proposed: the smart access point with limited advertised window (SAP-LAW). The main idea is to hijack at the gateway the acknowledge packets in the transmission control protocol (TCP) connections in order to artificially reduce the advertised destination window according to some bandwidth allocation policy. Therefore, the flux control mechanism is artificially exploited to control the congestion at the bottleneck. The advantage of this approach is that it does not drop any packet and does not require any modification in the TCP implementations at the clients. While the most popular congestion avoidance mechanisms are the explicit congestion notification (ECN) and the random early detection (RED). In this paper, we propose stochastic models for the ECN/RED and SAP-LAW mechanisms in order to compare their performances under different scenarios. The models are studied in mean field regime, i.e. under a great number of TCP connections and UDP-based transmissions. Different from previous work for the ECN/RED, in this paper, we consider the presence of UDP traffic with bursts and the case of not greedy TCP connections. The models for SAP-LAW are totally new. The comparison is performed in terms of different performance indices including average queue length, system throughput, and expected waiting time.

Mitigating Intra Flow Interference Over Multi Hop Wireless Ad Hoc Networks.

Transmission Control Protocol (TCP) is a predominant transport layer protocol for data transmission. The burst nature of TCP congestion control mechanism has often lead to heavy link layer contentions over multi hop ad hoc networks. Acknowledgements (ACK) that compete with the data packets for medium access in the reverse path, further add up to the contention levels. Such intense contention paves way to interference and reduces the throughput. In this paper, we propose a framework that ties up rate controlled cross layer transport solution (CLTSP) with opportunistic network coding to minimize the intra flow interference over wireless ad hoc networks. CLTSP performs rate controlled transmission to prevent self interference among data packets by spacing them out at an appropriate interval. The time interval between the deliveries of successive data packets is dynamically measured based on four hop propagation delay and an appropriate correction factor that are collected from intermediate nodes. Besides, we perform network coding over the data and ACK packets pertaining to the same connection to reduce intra flow contention. We use the basic idea of piggy code and incorporate effective buffer management which is opportunistic with CLTSP. We evaluate the performance of our protocol with TCP New Reno, Piggy code and show significant improvement in terms of throughput, Packet Delivery Ratio, Packet drops and Link layer collisions.

A Survey on TCP Congestion Control Schemes in Guided Media and Unguided Media Communication

Transmission Control Protocol (TCP) is a widely used end-to-end transport protocol in the Internet. This End to End delivery in wired (Guided) as well as wireless (Unguided) network improves the performance of transport layer or Transmission control Protocol (TCP) characterized by negligible random packet losses. This paper represents tentative study of TCP congestion control principles and mechanisms. Modern implementations of TCP hold four intertwined algorithms: slow start, congestion avoidance, fast retransmits, and fast recovery in addition to the standard algorithms used in common implementations of TCP. This paper describes the performance characteristics of four representative TCP schemes, namely TCP Tahoe, Reno, New Reno and Vegas under the condition of congested link capacities for wired network as well as wireless

TCP-CC: cross-layer TCP pacing protocol by contention control on wireless networks

Transmission Control Protocol (TCP) performs poorly over wireless networks. Some research indicates that the TCP congestion control mechanism may cause burstiness in the traffic flow. Numerous TCP segments are delivered simultaneously, while an acknowledgement of a retransmission is successfully received. Burstiness leads to a highly contentious network, which markedly increases the probability of packet loss on wireless networks. TCP pacing is a possible solutions for TCP burstiness on multi-hop networks. In this algorithm, TCP segment transmissions are distributed over the whole Round Trip Time. Most pacing protocols attempt to insert a delay interval into the TCP transmissions. However, there is a similar pacing algorithm in IEEE802.11, known as the contention window mechanism. In this paper, we first measure and analyze the way that the contention window size affects TCP throughput in different scenarios. We propose a cross-layer TCP pacing protocol by contention control in the MAC layer, called TCP Contention Control (TCP-CC). It adjusts the lower bound of the contention window in order to optimize the overall TCP throughput in both one-hop and multi-hop topology. Finally, comparative simulations are conducted in order to verify the improvements of our protocol on both TCP Reno and TCP Vegas.

Transport layer performance analysis and optimization for smart metering infrastructure

In a smart power grid, collecting data from a large number of smart meters and sensors over the conventional one-hop transmission control protocol (TCP) communication is prone to a high packet loss rate and degraded throughput due to the ineffectiveness of the TCP congestion control mechanism. The Split and Aggregated TCP (SA-TCP) proposes upgrading intermediate devices (known as regional collectors or RCs) to combine meters׳ TCP connections and forward data over a unified TCP connection to the utility server.This paper provides a comprehensive performance analysis of the SA-TCP scheme. It studies the impact of varying various parameters on the scheme, including the impact of network link capacity, buffering capacity of RCs, propagation delay between the meters and the utility server, and finally the number of RCs utilized as SA-TCP aggregators. The performance results show that by adjusting those parameters, it is possible to tune throughput of a smart metering network to the desired amount while keeping the deployment cost minimal.

An analysis of energy consumption for TCP data transfer with burst transmission over a wireless LAN

SummaryA common strategy for energy saving in wireless network devices is to remain in sleep mode for as long as possible. The timing of packet transmission and reception depends on the behavior of the transport‐layer protocols used by upper‐layer applications. Therefore, understanding the relation between the behavior of the transport‐layer protocols and energy efficiency using sleep mode is important for effective energy saving, especially when a wireless network interface (WNI) is activated in sleep mode at packet interarrivals. In this paper, we analyze the energy consumption of a client's WNI in Transmission Control Protocol (TCP) data transfer over a wireless LAN by focusing on the detailed behavior of TCP congestion control mechanisms. This model considers three situations: the WNI is activated in continuously active mode, in sleep mode, and in sleep mode with burst transmission. The latter is proposed as an effective method to improve energy efficiency, which lengthens sleep periods by transmitting and receiving multiple packets in a bursty fashion. Through numerical examples, we show that sleeping without modification of transmission timing reduces energy consumption in TCP data transfer by only around 10%, and that the burst transmission can contribute further 50% energy reduction. Copyright © 2014 John Wiley & Sons, Ltd.

Improved TCP Congestion Control Mechanism for Multihop Wireless Networks

Transmission Control Protocol (TCP) is working well in wired networks. TCP needs modification to work well in wireless networks. This work analyses the performance of the proposed two TCP cross layer flavours, namely the TCP-AL and TCP-WPAL. The cross layer interaction (TCP-WPAL) produces better performance than the TCP-AL. The PDR (Packet Delivery Ratio) of the TCP-WPAL is increased, and the delay and jitter of the TCP-WPAL are decreased in multihop wireless networks. Keywords: TCP, Wireless networks, TCP-AL and TCP-WPAL

A stochastic model for the behavior of multiple TCP NewReno sources over optical burst switching network

This work proposes a stochastic model to characterize the transmission control protocol (TCP) over optical burst switching (OBS) networks which helps to understand the interaction between the congestion control mechanism of TCP and the characteristic bursty losses in the OBS network. We derive the steady-state throughput of a TCP NewReno source by modeling it as a Markov chain and the OBS network as an open queueing network with rejection blocking. We model all the phases in the evolution of TCP congestion window and evaluate the number of packets sent and time spent in different states of TCP. We model the mixed assembly process, burst assembler and disassembler modules, and the core network using queueing theory and compute the burst loss probability and end-to-end delay in the network. We derive expression for the throughput of a TCP source by solving the models developed for the source and the network with a set of fixed-point equations. To evaluate the impact of a burst loss on each TCP flow accurately, we define the burst as a composition of per-flow-bursts (which is a burst of packets from a single source). Analytical and simulation results validate the model and highlight the importance of accounting for individual phases in the evolution of TCP congestion window.

Impact of Doppler spread and adaptive modulation on TCP throughput in Rayleigh fading channels

A number of wireless systems have recently adopted adaptive modulation (AM) schemes to improve its efficiency. In this letter, our aim is to study the impact Doppler spread and adaptive modulation has on transmission control protocol (TCP) throughput in Rayleigh fading channels. We consider a finite state Markov channel (FSMC) model, which is a useful model for analyzing radio channel with nonindependent fading. Furthermore, we use a Markov model for TCP evolution and evaluate the TCP performance by computer simulations. In our simulations we have compared the TCP Reno scheme with TCP Tahoe scheme. The results indicate that a large Doppler spread leads to lower TCP throughput due to more frequent transitions of channel states and modulation schemes which make it difficult for the TCP congestion control mechanism to accommodate the dynamic link characteristics.

Effects of the transmission control protocol congestion-control mechanism on the self-similarity of network traffic

A number of studies on traffic measurement from a variety of working networks have demonstrated that actual network traffic is self-similar in nature (traffic observed at different time resolutions has similar statistical properties, and this phenomenon cannot be modeled well by traditional traffic models such as Poisson and Markovian processes). The causes of self-similarity of network traffic must be identified because understanding the nature of network traffic is critical to properly design and implement computer networks and network services. In this paper, the effects of the transmission control protocol congestion-control mechanism on traffic self-similarity are investigated.