TCP-friendly Rate Control Protocol Research Articles

Simulated Performance of SCTP and TFRC Over MANETs

Mobile ad-hoc networks (MANETs) are composed of mobile nodes communicating through wireless medium, without any fixed centralized infrastructure. Providing quality of service (QoS) support to multimedia streaming applications over MANETs is vital. This paper focuses on QoS support, provided by the stream control transmission protocol (SCTP) and the TCP-friendly rate control (TFRC) protocol to multimedia streaming applications over MANETs. In this study, three QoS parameters were considered jointly: (1) packet delivery ratio (PDR), (2) end-to-end delay, (3) and throughput. Specifically, the authors analyzed and compared the simulated performance of the SCTP and TFRC transport protocols for delivering multimedia streaming over MANETs. Two simulation scenarios were conducted to study the impact of traffic load and node speed (mobility) to their performance. Based on the simulation results, the authors found that the PDR and the end-to-end delay of TFRC are slightly better than those of SCTP in both scenarios. Additionally, the performance of SCTP is significantly better than TFRC in terms of throughput.

Performance Evaluation of UDP, DCCP, SCTP and TFRC for Different Traffic Flow in Wired Networks

<p>The demand for internet applications has increased rapidly. Providing quality of service (QoS) requirements for varied internet application is a challenging task. One important factor that is significantly affected on the QoS service is the transport layer. The transport layer provides end-to-end data transmission across a network. Currently, the most common transport protocols used by internet application are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). Also, there are recent transport protocols such as DCCP (data congestion control protocol), SCTP (stream congestion transmission protocol), and TFRC (TCP-friendly rate control), which are in the standardization process of Internet Engineering Task Force (IETF). In this paper, we evaluate the performance of UDP, DCCP, SCTP and TFRC protocols for different traffic flows: data transmission, video traffic, and VOIP in wired networks. The performance criteria used for this evaluation include throughput, end to end delay, and packet loss rate. Well-known network simulator NS-2 used to implement the UDP, DCCP, SCTP, and TFRC protocols performance comparison. Based on the simulation results, the performance throughput of SCTP and TFRC is better than UDP. Moreover, DCCP performance is superior SCTP and TFRC in term of end-to-end delay.</p>

Efficient Traffic Engineering Strategies for Improving the Performance of TCP Friendly Rate Control Protocol

Multimedia services will play a prominent role in the next generation of internet. With increasing real time requirements, internet technology has to provide Quality of Service (QoS) for various kinds of real time streaming services. When the bandwidth required exceeds the available network resources, network paths can get congested, which results in a delay in packet delivery and packet loss. This situation leads to the design of new strategies for congestion avoidance and control. One of the popular and appropriate congestion control mechanisms that is useful in transmitting multimedia applications in the transport layer is TCP Friendly Rate Control Protocol (TFRC). However, TFRC still suffers from packet loss and delay due to long distance heavy traffic and network fluctuations. This paper introduces a number of key concerns like enhanced Round Trip Time (RTT) and Retransmission Time Out (RTO) calculations, Enhanced Average Loss Interval (ALI) methods and improved Time to Live (TTL) features are applied to TFRC to enhance the performance of TFRC over wired networks.

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.

Research on Self-adaptive TFRC Congestion Control of Streaming Media in Wireless Network

Transport layer protocol, for lack of effective congestion control, made an irrational bandwidth utilization ratio between UDP and TCP. Especially for streaming media transport which is easily to cause the network congestion. TFRC (TCP-friendly rate control protocol) congestion control mechanism had solved the problem effectively. However, in the high bit error rate environment of wireless network, TFPC would mistake the bit error for congestion lost packet that degrades throughput excessively. Concerning this issue, this paper put forward a self-adaptive TFRC mechanism which distinguishes congest and bit error effectively by distinguishing parameters, and adjusts the transmission rate dynamically. Simulation result reveals that self-adaptive TFRC mechanism can use link efficiently, reduce delay variation and meet the live transmission requirement of streaming media in wireless network.

Enhanced TCP-friendly rate control for supporting video traffic over internet

Video traffic nowadays forms the majority of traffic over the Internet, and is predicted to be the most prevailing traffic type in the coming few years. TCP-Friendly Rate Control (TFRC) is one of the most promising end-to-end congestion control protocols that is intended for unicast playback of Internet streaming applications. This paper presents a new TCP-Friendly congestion control protocol, called Enhanced TCP-Friendly Rate Control (ETFRC), for supporting real time video traffic over the Internet. The proposed protocol is developed by adjusting the sending rate, at the sender side, dynamically based on the current state of the network, and the current state of the receiver. In other words, ETFRC embodies a new algorithm to tune (increase or decrease) the sending rate, at the sender side, according to the difference between the calculated rate by the sender and the reported rate from the receiver side. The performance of the proposed ETFRC protocol is evaluated using the network simulator ns-2 considering different scenarios. In these scenarios, simulated video traffic from the Evalvid framework is sent over the designed topology and different performance parameters are measured and compared with that obtained by applying the original TFRC protocol. The simulation results show that ETFRC performance surpassed TFRC in terms of throughput, jitter, and packet loss.

ETFRC: Enhanced TFRC for Media Traffic

Due to the remarkable increase in media traffic over Internet, its congestion state is expected to worsen. TCP-friendly rate control protocol TFRC is one of the most promising congestion control techniques developed so far. TFRC has been thoroughly tested in terms of being TCP-friendly, responsive, and fair. Yet, its impact on the visual quality and the peak signal-tonoise ratio PSNR of the media traffic traversing Internet is still questionable. In this paper we aimed to point out the enhancement required for TFRC that enables producing the maximum PSNR value for Internet media traffic. Firstly, we suspected the default value of Nfb that represents the frequency of feedback messages sent by TFRC receiver to its sender every round-trip time RTT to be the optimum for our goal. Secondly, we managed to modify the mechanism of TFRC by changing this default value of Nfb over a range of values aiming to reach the required optimum. Thirdly, we investigated the effect of such variation over a simulated network environment to study its effect on the resulting PSNR for a number of arbitrary video sequences. Finally, our simulations results showed that running TFRC with Nfb=4 led to reaching the maximum PSNR values among all the examined values of Nfb including its default value. We hereby suggest using an enhanced TFRC that we abbreviated as ETFRC which has the Nfb value set to four as a replacement for the traditional TFRC to enable reaching higher PSNR for media traffic over Internet. Kerwords—TFRC, Congestion Control, PSNR

Dynamic FEC Algorithms for TFRC Flows

Media flows coexist with TCP-based data traffic on the Internet and are required to be TCP-friendly. The TCP protocol slowly increases its sending rate until episodes of congestion occur, and then it quickly reduces its rate to remove congestion. However, media flows can be sensitive to even brief episodes of congestion. In this paper, we are interested in protecting media flows from TCP-induced congestion while maintaining their TCP friendliness. In particular, we consider media flows carried over the TCP-Friendly Rate Control (TFRC) protocol and we design algorithms that dynamically adapt the level of forward error correction (FEC) based on the congestion state of the network. To this end, first, we investigate the loss and delay characteristics of TFRC flows in several TCP-induced congestion scenarios, and we develop novel predictors of loss events based on packet delay information. Second, we use these predictors to dynamically adapt the level of FEC protection based on the predicted level of congestion. We show that this technique can significantly improve the overhead versus reliability trade-off compared to fixed FEC. Third, we select the FEC and original media packets within each FEC block, in a rate-distortion optimized way, and we show that this technique significantly improves media quality.

CASHeW: Cluster-based Adaptive Scheme for Multimedia Delivery in Heterogeneous Wireless Networks

Multimedia streaming over heterogeneous wireless networks has attracted significant interest in recent years from both telecom network operators and end users. However, the heterogeneity of the wireless network makes it very difficult to synchronize real-time multimedia streaming to different types of end-user devices across different wireless networks. In addition, with different delay and packet loss across different networks, multimedia delivery over the heterogeneous wireless networks cannot provide good quality streaming video. This paper proposes CASHeW--a novel cluster-based design with an in-built feedback-based adaptive mechanism that results in a higher video perceived quality in two-hop heterogeneous wireless network environments. CASHeW employs a proxy-client-server mechanism between the base station (BS) and the end-user; and importantly uses a quality-oriented adaptive scheme for efficient multimedia delivery. Simulation-based tests indicate that the performance of CASHeW not only outperforms transport layer adaptive delivery protocols like the TCP-Friendly Rate Control Protocol (TFRCP) and Loss Delay Adaptation (LDA+), but also is better than that of medium access control (MAC) layer protocols such as the Receiver Based Auto Rate (RBAR) and Enhanced Distributed Channel Access (EDCA) in terms of average perceived quality, average bit rate and loss rate.

QoS Modeling for End-to-End Performance Evaluation over Networks with Wireless Access

This paper presents an end-to-end Quality of Service (QoS) model for assessing the performance of data services over networks with wireless access. The proposed model deals with performance degradation across protocol layers using a bottom-up strategy, starting with the physical layer and moving on up to the application layer. This approach makes it possible to analytically assess performance at different layers, thereby facilitating a possible end-to-end optimization process. As a representative case, a scenario where a set of mobile terminals connected to a streaming server through an IP access node has been studied. UDP, TCP, and the new TCP-Friendly Rate Control (TFRC) protocols were analyzed at the transport layer. The radio interface consisted of a variable-rate multiuser and multichannel subsystem, including retransmissions and adaptive modulation and coding. The proposed analytical QoS model was validated on a real-time emulator of an end-to-end network with wireless access and proved to be very useful for the purposes of service performance estimation and optimization.

Equation-based end-to-end single-rate multicast congestion control

Among the recently proposed single-rate multicast congestion control protocols is transmission control protocol-friendly multicast congestion control (TFMCC; Widmer and Handley 2001; Floyd et al. 2000; Widmer et al. IEEE Netw 15:28–37, 2001), which is an equation-based single-rate protocol that extends the mechanisms of the unicast TCP-friendly rate control (TFRC) protocol into the multicast domain. In TFMCC, each receiver estimates its throughput using an equation that estimates the steady-state throughput of a TCP source. The source then adjusts its sending rate according to the slowest receiver within the session (a.k.a., current-limiting receiver, CLR). TFMCC is a relatively simple, scalable, and TCP-friendly multicast congestion control protocol. However, TFMCC is hindering its throughput performance by adopting an equation derived from the unicast TFRC protocol. Further, TFMCC is slow to react to congestion conditions that usually result in a change of the CLR. This paper is motivated by these two observations and proposes an improved version of TFMCC, which we refer to as hybrid-TFMCC (or H-TFMCC for short). First, each receiver estimates its throughput using an equation that models the steady-state throughput of a multicast source controlled according to the additive increase multiplicative decrease (AIMD) approach. The second modification consists of adopting a hybrid sender/receiver-based rate control strategy, where the sending rate can be adjusted by the source or initiated by the current or a new CLR. The source monitors RTT variations on the CLR path, in order to rapidly adjust the sending rate to network conditions. Simulation results show that these modifications result in remarkable performance improvement with respect to throughput, time to react, and magnitude of oscillations. We also show that H-TFMCC remains TCP-friendly and achieves a higher fairness index than that achieved by TFMCC.

MulTFRC

When data transfers to or from a host happen in parallel, users do not always consider them to have the same importance. Ideally, a transport protocol should therefore allow its users to manipulate the fairness among flows in an almost arbitrary fashion. Since data transfers can also include real-time media streams which need to keep delay | and hence buffers | small, the protocol should also have a smooth sending rate. In an effort to satisfy the above requirements, we present MulTFRC, a congestion control mechanism which is based on the TCP-friendly Rate Control (TFRC) protocol. It emulates the behavior of a number of TFRC flows while maintaining a smooth sending rate. Our simulations and a real-life test demonstrate that MulTFRC performs significantly better than its competitors, potentially making it applicable in a broader range of settings than what TFRC is normally associated with.

End-to-end optimized TCP-friendly rate control for real-time video streaming over wireless multi-hop networks

Rate control is an important issue in video streaming applications. The most popular rate control scheme over wired networks is TCP-Friendly Rate Control (TFRC), which is designed to provide optimal transport service for unicast multimedia delivery based on the TCP Reno’s throughput equation. It assumes perfect link quality, treating network congestion as the only reason for packet losses. Therefore, when used in wireless environment, it suffers significant performance degradation because of packet losses arising from time-varying link quality. Most current research focuses on enhancing the TFRC protocol itself, ignoring the tightly coupled relation between the transport layer and other network layers. In this paper, we propose a new approach to address this problem, integrating TFRC with the application layer and the physical layer to form a holistic design for real-time video streaming over wireless multi-hop networks. The proposed approach can achieve the best user-perceived video quality by jointly optimizing system parameters residing in different network layers, including real-time video coding parameters at the application layer, packet sending rate at the transport layer, and modulation and coding scheme at the physical layer. The problem is formulated and solved as to find the optimal combination of parameters to minimize the end-to-end expected video distortion constrained by a given video playback delay, or to minimize the video playback delay constrained by a given end-to-end video distortion. Experimental results have validated 2–4 dB PSNR performance gain of the proposed approach in wireless multi-hop networks by using H.264/AVC and NS-2.

Rate-adaptive video streaming through packet dispersion feedback

The anticipated growth of IPTV makes selection of suitable congestion controllers for video-stream traffic of vital concern. Measurements of packet dispersion at the receiver provide a graded way of estimating congestion, which is particularly suited to video as it does not rely on packet loss. A closed-loop congestion controller, which dynamically adapts the bitstream output of a transcoder or video encoder to a rate less likely to lead to packet loss, is presented. The video congestion controller is based on fuzzy logic with packet dispersion and its rate of change forming the inputs. Compared with TCP emulators such as TCP-friendly rate control (TFRC) and rate adaptation protocol (RAP), which rely on packet loss for real-time congestion control, the fuzzy-logic trained system's sending rate is significantly smoother when multiple video-bearing sources share a tight link. Using a packet dispersion method similarly results in a fairer allocation of bandwidth than TFRC and RAP. These gains for video traffic are primarily because of better estimation of network congestion through packet dispersion but also result from accurate interpretation by the fuzzy-logic controller.

Throughput Analysis of TCP-Friendly Rate Control in Mobile Hotspots

By integrating wireless wide area networks (WWANs) and wireless local area networks (WLANs), mobile hotspot technologies enable seamless Internet multimedia services to users on-board a vehicle. In this paper, we investigate the performance of TCP-Friendly Rate Control (TFRC) protocol supporting multimedia services in mobile hotspots. To quantify the throughput of TFRC flows in mobile hotspots, we first develop discrete-time queuing models for the WWAN link and the WLAN link. We then derive the steady state TFRC throughput using an iterative algorithm. Analytical and extensive simulation results reveal how the end-to-end TFRC throughput is affected by the number of users in a mobile hotspot, the vehicle velocity, the WWAN/WLAN link bandwidth, the retransmission limit, and the buffer size. It is found that the WWAN channel profile and link bandwidth have significant impacts on the TFRC throughput, and therefore suitable resource allocation and admission control are indispensable for the quality and efficiency of multimedia services in mobile hotspots.

An integrated rate control scheme for TCP-friendly MPEG-4 video transmission

Delivering MPEG-4 real-time video over the Internet requires the use of rate control schemes in both the compression and the transport domains. This paper discusses the practical difficulties involved in integrating MPEG-4 scalable rate control (SRC) in the compression domain with TCP-friendly rate control (TFRC) in the transport domain. In addition to the requirement for rate matching between the two schemes to ensure TCP-friendliness, users demand a high-quality, smooth media output under the varying network conditions. In this paper, an integrated rate control scheme is proposed for MPEG-4 video transported by a TFRC protocol. The proposed scheme comprises a rate smoothing control mechanism to meet the rate matching with the controlled transmission buffering delay, and an adaptive rate control for the I-frame designed to reduce the frame skipping. Through the successful integration of the two schemes, the experimental results show that the proposed scheme better preserves the motion smoothness and improves the overall perceptual quality for TCP-friendly MPEG-4 video transmissions to obtain a smooth, high visual quality video experience.

A Two-Phase Loss Differentiation Algorithm for Improving TFRC Performance in IEEE 802.11 WLANs

In IEEE 802.11 WLANs, packet losses may be due to buffer overflow, transmission errors, or collisions. Therefore, the performance of TCP-Friendly Rate Control (TFRC) in IEEE 802.11 WLANs largely depends on its ability to differentiate packet losses resulting from network congestion (due to buffer overflow and collisions) and those from transmission errors. In this paper, an enhanced TFRC (E-TFRC) protocol is proposed to detect and identify the cause of packet loss events through a novel two-phase loss differentiation algorithm (TP-LDA). The packet losses due to buffer overflow and those due to failed transmissions in WLANs are first differentiated. For failed transmissions, the fraction of those due to collisions is obtained with the assistance of the lower layer. By employing TP-LDA, only the packet losses due to buffer overflow and collisions are notified to the sender for appropriate flow and congestion control. To quantify the performance of TFRC and E-TFRC over WLANs, a continuous-time Markov chain based on a new WLAN link model is developed by considering both collisions and transmission errors. Analytical and simulation results demonstrate that, with appropriate loss differentiation, E-TFRC can achieve higher throughput than TFRC in WLANs with different channel profiles.

Equation based rate control scheme for video streaming over wireless channels with link level ARQ

Equation based TCP-friendly rate control (TFRC) protocol has been proposed to support video streaming applications. In order to improve TFRC performance in wireless channels, the link level automatic repeat request (ARQ) scheme is usually deployed. However, ARQ cannot ensure strict delay guarantees, especially over multihop links. This paper introduces a theoretical model to deduce an equation for packet size adjustment in transport layer to minimize retransmission delay by taking into consideration the causative reasons inducing retransmission in link layer. An enhanced TFRC (ETFRC) scheme is proposed integrating TFRC with variable packet size policy. Simulation results demonstrate that higher goodput, lower packet loss rate (PLR), lower frame transmission delay and jitter with good fairness can be achieved by our proposed mechanism.

Efficient Delivery of Multimedia Streams Over Broadband Networks Using QOAS

Quality Oriented Adaptation Scheme (QOAS) is compared against other adaptive schemes such as TCP Friendly Rate Control Protocol (TFRCP), Loss-Delay-based Adaptation Algorithm (LDA+), and a nonadaptive (NoAd) solution when streaming multiple multimedia clips with various characteristics over broadband networks. Streaming efficiency is assessed in terms of loss rate, bandwidth utilization, number of concurrent clients and end-user perceived quality. Simulation results show that using QOAS a significantly higher number of simultaneous clients can be served than when using the other schemes given a target average end-user quality. This is while having higher bandwidth utilization. Testing results also indicate that higher performance is achieved when streaming to the same number of clients using QOAS than when other solutions are used.

Performance analysis of TFRC over wireless link with truncated link-level ARQ

In this paper, an analytical framework is proposed for evaluating the quality of service (QoS) of TCP-friendly rate control protocol (TFRC) in hybrid wireless/wired networks. For the wireless network, a link-level truncated automatic repeat request (ARQ) scheme is deployed to reduce the packet losses visible to the transport layer protocol. Two discrete time Markov chains (DTMC) are introduced to analyze the network performance and the QoS of the TFRC protocol, in terms of wireless link utilization, flow throughput, packet loss rate, and probability of end-to-end delay exceeding a prescribed threshold. Extensive simulations are performed to verify the accuracy of the analytical results. It is concluded that the analytical results are useful for optimizing the system parameters, such as the interface buffer size and the maximum number of retransmissions of the truncated ARQ scheme. With the optimal parameters, wireless link utilization can be maximized, and the QoS requirements of multimedia applications can be statistically guaranteed.