TCP Mechanism Research Articles

Hierarchically porous bone scaffold fabricated via direct foam writing with TCP/ZrO2 composite ink

Customizing bone scaffolds to mimic the hierarchically porous structure of natural bone presents a promising strategy for treating critical bone defects. Although low-cost direct ink writing (DIW) is often used to customize bone scaffolds, the limited print resolution made it difficult to print microporous structures. In this study, DIW was combined with the direct foam method to construct bone scaffolds with hierarchical and interconnected macro-micro porous structures. The foam stabilization mechanism of pure TCP was investigated to prepare TCP-enhanced ZrO2-based composite foam inks. Incorporating TCP endowed a richer interconnection structure to the composite foam. The printed bone scaffolds feature three scales of pore structure: interconnected macropores of 400–500 μm, bubble template pores of 50 μm, and open pores of <20 μm. The scaffold exhibited properties comparable to cancellous bone, such as 90 % porosity, 3.1 MPa compressive strength, and 1.0 GPa elastic modulus. In vitro experiments have demonstrated that cells can grow into the interior of the scaffold by following the connecting pores. And, incorporating TCP significantly enhances osteogenic protein and gene expression in bionic bone scaffolds. This facile and controllable approach offers an alternative solution to addressing the challenge of clinical implant shortages.

A faster failure recovery mechanism for Multipath TCP

A faster failure recovery mechanism for Multipath TCP

Identification of two possible metabolic pathways responsible for the biodegradation of 3, 5, 6-trichloro-2-pyridinol in Micrococcus luteus ML.

3, 5, 6-Trichloro-2-pyridinol (TCP) is a metabolite of the insecticide chlorpyrifos and the herbicide triclopyr, and it is higher toxic than the parent compounds. Microbially-mediated mineralization appears to be the primary degradative pathway and the important biological process of detoxification. However, little information is available on TCP complete metabolic pathways and mechanisms. In this study, the degradation of TCP was studied with a novel strain Micrococcus luteus ML isolated from a stable TCP degrading microbiota. Strain ML was capable of degrading 61.6% of TCP (50mg/L) and 35.4% of chlorpyrifos (50mg/L) at 24h and 48h under the optimal conditions (temperature: 35°C; pH: 7.0), respectively. It could also degrade 3, 5-dichloro-2-pyridone, 6-chloropyridin-2-ol, 2-hydroxypyridine and phoxim when provided as sole carbon and energy sources. Seven TCP intermediate metabolites were detected in strain ML and two possible degradation pathways of TCP were proposed on the basis of LC-MS analysis. Both the hydrolytic-oxidative dechlorination pathway and the denitrification pathway might be involved in TCP biodegradation by strain ML. To the best of our knowledge, this is the first report on two different pathways responsible for TCP degradation in one strain, and this finding also provides novel information for studying the metabolic mechanism of TCP in pure culture.

T-RACKs: A Faster Recovery Mechanism for TCP in Data Center Networks

Cloud interactive data-driven applications generate swarms of small TCP flows that compete for the small switch buffer space in data-center. Such applications require a small flow completion time (FCT) to be effective. Unfortunately, TCP is myopic with respect to the composite nature of application data. In addition it tends to artificially inflate the FCT of individual flows by several orders of magnitude, because of its Internet-centric design, that fixes the retransmission timeout (RTO) to be at least hundreds of milliseconds. To better understand this problem, in this paper, we use empirical measurements in a small data center testbed to study, at a microscopic level, the effects of various types of packet losses on TCP's performance. In particular, we single out packet losses that impact the tail end of small flows, as well as bursty losses that span a significant fraction of small TCP congestion windows, and show a non-negligible effect of such losses on the FCT. Based on this, we propose the so-called, timely-retransmitted ACKs (or T-RACKs), a simple loss recovery mechanism that conceals the drawbacks of the long RTO even in the presence of heavy packet losses. Interestingly enough, T-RACKS achieves this transparently to TCP itself as it does not require any change to TCP in the tenant's virtual machine (VM) or container. T-RACKs can be implemented as a software shim layer in the hypervisor between the VMs and the server's NIC or in hardware as a networking function in a SmartNIC. Simulation and real testbed results show remarkable performance improvements.

On Enhancing TCP to Deal with High Latency and Transmission Errors in Geostationary Satellite Network for 5G-IoT

The geostationary (GEO) satellite networks have two important influencing factors: high latency and transmission errors. Similarly, they will happen in the large-scale multihop network of the Internet of things (IoT), which will affect the application of 5G- (5th-generation mobile networks-) IoT. In this paper, we propose an enhanced TCP mechanism that increases the amount of data transferred in the slow start phase of TCP Hybla to mitigate the effect of long RTT and incorporates a refined mechanism of TCP Veno, which can distinguish packet loss between random and congestion. This scheme is evaluated and compared with NewReno, Hybla, and Veno by simulation, and the performance improvement of the proposed TCP scheme for GEO satellite network in the presence of random packet losses is demonstrated. At the same time, the enhanced TCP scheme can improve the transmission performance in the future 5G-IoT heterogeneous network with high delay and transmission .

Assessing the performance of different TCP congestion mechanisms in underwater wireless sensor networks

Data transmission in Underwater Wireless Sensor Networks (UWSNs) is one of the key enablers used in technologies for future ocean-monitoring systems and other underwater applications. The use of acoustic waves in UWSNs suffer from a high propagation delay, as well as a limited available bandwidth due to the high-noise level, making the use of the different traditional existing protocols a major challenge in this environment. In this paper, we have chosen two TCP mechanisms already defined: TCP Vegas and TCP New Reno, to evaluate the effects of variable TCP packet size and TCP connection density in a subsea network under two common routing protocols, namely AODV and DSDV. The simulation results show that the performances of the two TCPs using DSDV routing protocol provide a more efficient result than those using the AODV routing protocol and that New Reno TCP gives better results than Vegas TCP in the UWSNs.

Challenges on the Way of Implementing TCP Over 5G Networks

5G cellular communication, especially with its hugely available bandwidth provided by millimeter-wave, is a promising technology to fulfill the coming high demand for vast data rates. These networks can support new use cases such as Vehicle to Vehicle and augmented reality due to its novel features such as network slicing along with the mmWave multi-gigabit-per-second data rate. Nevertheless, 5G cellular networks suffer from some shortcomings, especially in high frequencies because of the intermittent nature of channels when the frequency rises. Non-line of sight state, is one of the significant issues that the new generation encounters. This drawback is because of the intense susceptibility of higher frequencies to blockage caused by obstacles and misalignment. This unique characteristic can impair the performance of the reliable transport layer widely deployed protocol, TCP, in attaining high throughput and low latency throughout a fair network. As a result, the protocol needs to adjust the congestion window size based on the current situation of the network. However, TCP is not able to adjust its congestion window efficiently, and it leads to throughput degradation of the protocol. This paper presents a comprehensive analysis of reliable end-to-end communications in 5G networks. It provides the analysis of the effects of TCP in 5G mmWave networks, the discussion of TCP mechanisms and parameters involved in the performance over 5G networks, and a survey of current challenges, solutions, and proposals. Finally, a feasibility analysis proposal of machine learning-based approaches to improve reliable end-to-end communications in 5G networks is presented.

Mean platelet volume: Should we really eye on?

Introduction: Mean platelet volume (MPV) is a hematology analyzer generated measurement of the average size of platelets found in peripheral blood. Thrombocytopenia could be because of accelerated destruction, impaired production or abnormal pooling in spleen. Analyses of MPV values play an important role in assessing the mechanism for TCP. Material and Methods: 800 blood samples of patients with platelet count 1,50,000 ul were studied. Hematological analysis was done by Sysmex KX-21. Platelet count and MPV of all the cases and control group were noted. The cases were grouped into various categories of A, B or C depending on mechanism of decrease in platelets. Data was analyzed and tested for statistical significance using one-way ANOVA and post hoc testing using Tukey’s test.Results: Majority of the cases in the present study were in group A (75.3%), followed by group B (23.9%) and group C (0.7%). A higher value of MPV (10.15±1.30 fl) was found in group A compared to other categories. Significant results of MPV were seen in group A and group B category.Conclusion: Mean platelet volume is an easily obtained platelet parameter which is helpful in delineating the various causes of TCPs. Hence an eye on the analyser readings of MPV helps in better targeted therapies.

The oxygen sensing mechanism of a triphenylamine-based cyclometalated platinum(II) complex

Triphenylamine-based cyclometalated platinum(II) (TCP) emits phosphorescence at room temperature. The phosphorescence was quenched by oxygen molecule, which means that TCP is a good candidate for oxygen molecule recognition and measurement. By the way of quantum chemical calculation, we proposed the quenching mechanism to elucidate the nature of oxygen sensing, which was different from the traditional dynamic collision mechanism. The luminescence mechanism of TCP involves phosphorescent emission, and the TCP-O2 complex fluorescent emission. By utilizing the density functional theory (DFT) method, we calculated the electron configurations and the frontier molecular orbitals of TCP and the TCP-O2 complex. Furthermore, applying the time-dependent density functional theory (TDDFT) method, we calculated the geometric optimization and the excitation energies of TCP and the TCP-O2 complex in the excited state. The results illustrate that the luminescence of TCP stems from localized excitation, while that of the TCP-O2 complex stems from delocalized excitation. Moreover, we also calculated the radiative and non-radiative rate constants of TCP and the TCP-O2 complex and clarified the photophysical processes of them. For TCP, first the electron arrived at the T1 state via intersystem crossing from the initial S1 state and finally back to the S0 state via emitting phosphorescence. For the TCP-O2 complex, with no spin flip, the electron jumped directly from the T1 to T0 state via internal conversion.

A Congestion Control Mechanism for Streaming Media Transmission over Wireless Environment

TFRC (TCP-Friendly Rate Control Protocol) has been recognized as a relatively good mechanism for TCP friendly congestion control on cable network. However, TFRC is sensitive to the network status and cannot actually distinguish congestion losses and noncongestion losses well in wireless networks. The high error rates and large delay of wireless networks result in significant performance degradation and poor quality of the streaming media transmission service in transmission. To solve this problem, this paper proposes an Explicit Congestion Notification TCP (ECN-TCP) based TCP Friendly Wireless streaming Media Rate Control (TF-WMRC) congestion control mechanism. This mechanism improves TFRC and conjunctions with ECN and RED (Random Early Detection) methods, differentiating correctly congestion losses and wireless error losses and effectively alleviating the throughput degradation caused by wireless links. Performance evaluation of network efficiency, TCP friendliness and streaming media stability in NS2 simulation platform has shown that it is a good congestion control mechanism for streaming media transmission in wireless environment.

TCP-Aware Backpressure Routing and Scheduling

In this work, we explore the performance of backpressure routing and scheduling for TCP flows over wireless networks. TCP and backpressure are not compatible due to a mismatch between the congestion control mechanism of TCP and the queue size based routing and scheduling of the backpressure framework. We propose a TCP-aware backpressure routing and scheduling mechanism that takes into account the behavior of TCP flows. TCP-aware backpressure provides throughput optimality guarantees in the Lyapunov optimization framework, and gracefully combines TCP and backpressure without making any changes to the TCP protocol. The simulation results show that TCP-aware backpressure (i) improves the throughput of TCP flows significantly, (ii) provides fairness across competing TCP flows, and (iii) accommodates both TCP and non-TCP flows in a wireless network, and improves throughput of these flows without hurting fairness.

병렬 TCP 통신을 이용한 스마트폰 실시간 스트리밍 서비스

ABSTRACT This paper proposed an efficient multiple TCP mechanism using Android smartphones for remote control video Wi-Fi stream transmission via network communications in real time. The wireless video stream transmission mechanism can be applied in various area such as real time server stream transmissions, movable drones, disaster robotics and real time security monitoring systems. Moreover, we urgently need to transmit data in timely fashion such as medical emergency, security surveillance and disaster prevention. Our parallel TCP transmission system can play an important role in several area such as real time server st ream transmissions, movable drones, disaster robotics and real time security monitoring systems as mentioned in the previous sentence. Therefore, we designed and implemented a parallel TCP transmission (parallel stream) for an efficient real time video streaming services. In conclusion, we evaluated proposed mechanism using parallel TCP transmission under various environments with performance analysis.

Server Side Solutions For Web-Based Video

In contemporary video streaming systems based on HTTP protocol, video players at the client side are responsible for adjusting video quality to network conditions and user expectations. However, when multiple video clips are streamed simultaneously, an intricate application logic implemented in the video players overlays the TCP mechanism which is responsible for a balanced access to a shared network link. As a result, some video players may not obtain a fair share of network throughput and may be vulnerable to an unstable video bit-rate. Therefore, we propose to simplify the algorithms implemented in the video players, which are responsible for the adjustment of video quality and constrain their functionality only to sending feedback to a server about a state of the player buffer. The main logic of the system is shifted to the server, which is now responsible for bit-rate selection and prioritisation of the video streams transmitted to multiple clients. To verify our proposition, we performed several experiments in a laboratory environment which show that when the server cooperates with the clients, the video players experience fewer quality switches and the system achieves better fairness when allocating network throughput among the video players. However, this comes at the cost of worse utilisation of network bandwidth.

Congestion Control Mechanism for TCP in Data Centered Networks Using Multithreading

Congestion Control Mechanism for TCP in Data Centered Networks Using Multithreading

TCPJGNC: A transport control protocol based on network coding for multi-hop cognitive radio networks

Cognitive radio (CR) has emerged as a promising solution to enhance spectrum utilization. In cognitive radio networks (CRNs), the secondary users (SUs) can opportunistically exploit frequency bands when the primary users (PUs) do not occupy the bands. However, TCP performance in CRNs may suffer from significant degradation due to this feature. In this paper, we investigate the limitations of TCP in multi-channel multi-radio multi-hop CRNs, and propose a novel transmission control protocol called TCPJGNC (TCP Joint Generation Network Coding, JGNC) based on network coding. In TCPJGNC, we dynamically adjust the number of packets involved in network coding according to the wireless communication environment to achieve better decoding probability. In the meantime, a coding scheme based on JGNC is provided which can reduce the number of retransmissions in TCPJGNC. In addition, we modify the TCP mechanism to fit into CRNs by considering the features of CRNs. An analysis of approximate expected throughput in TCPJGNC is provided and the simulation results indicate that TCPJGNC can significantly improve the network performance in terms of throughput, bandwidth efficiency and average end-to-end delay. To the best of our knowledge, TCPJGNC is the first transmission control protocol for multi-hop CRNs from a network coding perspective.

Investigations optimum scheduling and TCP mechanism of hybrid topology sensor network in building SHM

Abstract Sensor technology has opened up numerous opportunities to advanced health and maintenance monitoring of civil infrastructure such as large buildings. Compare to traditional tactics, it offers a better way of providing relevant information regarding the condition of building structure at a lower price and greater range. Numerous domestic buildings, especially long-span buildings, have a low-profile frequency response that is challenging to accurately measure with the application of sensors suitable for integration with lower-cost, lower-power-profile wireless sensor networks. To cover the whole area of interest, sensor network topology is one of the most important issues. The objective of this article is to investigate of hybrid topology scheduling algorithm to determine the optimum TCP (Transmission Control Mechanism) mechanism for assessing large building structural health data using various kinds TCP and scheduling algorithm. Result show that, the Full TCP mechanism is selected as optimum TCP mechanism for monitoring building structural health data.

HBDP 네트워크에서 C-TCP의 성능 향상을 위한 네트워크 적응적 혼잡제어 기법

오늘날 네트워크는 HBDP (High Bandwidth Delay Product) 특징을 가지고 있으며, 기존 TCP는 혼잡 윈도우 크기의 느린 증가와 패킷 손실 시 급격한 감소로 인하여 HBDP 네트워크에 적합하지 못하다. 기존 TCP의 문제를 해결하기 위해 새로운 혼잡 제어 기법에 관한 많은 연구들이 진행되었다. C-TCP (Compound-TCP)는 손실기반 TCP와 지연기반 TCP를 결합한 하이브리드 TCP이다. C-TCP의 목적은 빠른 대역폭 점유, 조기 혼잡예측에 의한 혼잡 방지와 공정성 보장이다. 하지만 C-TCP는 혼잡 정도를 고려하지 않는 지연 윈도우 감소율을 적용하기 때문에 성능의 저하를 초래한다. 제안하는 기법은 네트워크의 혼잡 상태에 따라 적응적으로 지연 윈도우의 증감률을 조절함으로써 C-TCP의 대역폭 점유 효율과 공정성을 개선한다. 실험 결과를 통해 HBDP 네트워크에서 제안하는 기법이 기존 C-TCP보다 향상된 성능을 보임을 확인하였다.

HBDP 네트워크에서 대역폭 점유와 RTT 공정성 향상을 위한 네트워크 적응적 혼잡제어 기법

These days, the networks have exhibited HBDP (High Bandwidth Delay Product) characteristics. The legacy TCP slowly increases the size of the congestion window and drastically decreases the size of a congestion window. The legacy TCP has been found to be unsuitable for HBDP networks. TCP mechanisms for solving the problems of the legacy TCP can be categorized into the loss-based TCP and the delay-based TCP. Most of the TCP mechanisms use the standard slow start phase, which leads to a heavy packet loss event caused by the overshoot. Also, in the case of congestion avoidance, the loss-based TCP has shown problems of wastage in terms of the bandwidth and RTT (Round Trip Time) fairness. The delay-based TCP has shown a slow increase in speed and low occupancy of the bandwidth. In this paper, we propose a new scheme for improving the over shoot, increasing the speed of the bandwidth and overcoming the bandwidth occupancy and RTT fairness issues. By monitoring the buffer condition in the bottleneck link, the proposed scheme does congestion control and solves problems of slow start and congestion avoidance. By evaluating performance, we prove that our proposed scheme offers better performance in HBDP networks compared to the previous TCP mechanisms.

Split-TCP based acceleration gateway over packet lossy networks

The conservative Additive Increase Multiplicative Decrease mechanism of traditional TCP causes the link under-utilization in the Wide Area Networks (WANs) due to the WANs' intrinsic nature of high latency and high packet loss. To alleviate the problem, we present the design and implantation of STAG, an Acceleration Gateway with Split-TCP in the paper. STAG is built on embedded network equipment and acts as a transparent proxy. In STAG, a new improved congestion control method named Rapid TCP is adopted, which determines whether or not to decrease the congestion window based on the packet loss trend. In particular, in the fast recovery phase, it chooses different window adjustment strategies based on the current size of congestion window to achieve higher utilization. The performance validation of STAG is done on both our emulation testbed and the real wide area network. The results show that STAG with Rapid TCP effectively adapts to the high loss network environment and significantly speeds up the applications without loss of fairness.

Adaptive TCP: A Sender Side Mechanism with Dynamic Adjustment of Congestion Control Parameters for Performance Improvement in WLAN

This paper presents a sender side only TCP mechanism to prevent compromise for bandwidth utilization in IEEE 802.11 wireless networks. In absence of mechanism for accurate and immediate loss discrimination, the TCP sender unnecessarily reduces its Loss Window in response to the packet losses due to transmission errors. At the same time, frequent transmission losses and associated link retransmissions cause inaccuracy for available bandwidth estimate. The proposal, Adaptive TCP tackles the above issues using two refinements. First, sender estimates the degree of congestion by exploiting the statistics for estimated Round Trip Time (RTT). With this, it prevents unnecessary shrinkage of Loss Window and bandwidth estimate. Second, by concluding the uninterrupted evolution of its sending rate in recent past, the Adaptive TCP advances bandwidth estimate under favorable network conditions. This in turn, facilitates for quick growth in TCP’s sending rate after loss recovery and consequently alleviates bandwidth utilization. The authors implement the algorithm on top of TCP NewReno, evaluate and compare its performance with the wireless TCP variants deployed in current Internet. Through intensive simulations it is demonstrated that the Adaptive TCP outperforms other well-established TCP variants, and yields more than 100% of the throughput performance and more than 60% of improvement for bandwidth utilization, compared to TCP NewReno. The simulation results also demonstrated compatibility of Adaptive TCP in a shared wireless environment.