Abstract—Due to the remarkable increase in media traffic over the existing best-effort IP Internet, the Internet congestion state is expected to worsen. TCP-friendly rate control protocol TFRC is one of the most promising congestion control techniques developed so far. Those techniques have been thoroughly tested in terms of being TCP-friendly and fair. Yet, their impact on the visual quality of the media traffic traversing Internet is still questionable. This paper investigates, in a simulated environment, the effect of incorporating TFRC on the peak signal-to-noise ratio PSNR of the transmitted video over Internet. A number of arbitrary raw videos are encoded, converted into trace files via a known tool-set, and then pushed into a simulated network environment to run over TFRC protocol with coexisting TCP flows. This scenario was run for a variety of videos having different content types, frame lengths, and motion complexity scale. The output video files of the simulations are then examined in terms of PSNR. TFRC was shown to produce visually meaningful and acceptable output video files. Some variations in the PSNR values were recorded among the simulated videos. TFRC performance on slow motion videos was slightly better than on medium-motion that was better than that on high-motion videos.

The remarkable increase in media traffic over Internet is expected to worsen its congestion state. 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-to- noise 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.

The The evident increase in media traffic over Internet is expected to worsen its congestion state. 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-to- noise ratio PSNR of the media traffic traversing Internet is still questionable. In this paper we aimed to point out the enhancements required for TFRC that enables producing the maximum PSNR value for Internet media traffic. Firstly, we suspected the default value of n that represents the number of loss intervals used in calculating the loss event rate in the TFRC equation. This value is recommended to be set to 8 according to the latest RFC of TFRC. We investigated the effect of modifying the TFRC

Round Trip Time values constitute one of the significant parameter available to a TCP sender for estimating the network conditions. The RTT has a significant effect on the throughput of a connection and creates the performance bottleneck for traditional AIMD TCP Protocol variants mainly when used for GEO satellite networks and other long fat networks. Many Transport Protocols like Vegas, Proactive TCP, and Westwood uses the RTT measurement for adjusting the congestion window and refining the Loss Detection Algorithms, which eventually determines the performance of the Protocol. RTT also appears in the empirical formulation of TCP throughput and protocols based on these empirical estimates. RTT is generally considered an independent parameter mainly dependent on the access delay, queuing delay, and the propagation delay of the concerned channel. In this paper, we have analyzed the dynamics of RTT behavior and shown how the congestion levels in the network, packet error rates and available buffer capacity affects the RTT measurements. The Mean RTT and the rate of change of RTT Mean values have been analyzed in different network conditions. These analysis have been carried out by simulation using ns2 considering a GEO Satellite network. errors, which are not common in the wired counterpart [30], [31], [32]. The RTT is constrained by the speed of light and the total amount of data that needs to be sent in one RTT is given by the bandwidth-delay product of the link concerned and is not really achieved by the acknowledgement driven logic of TCP [1], [3], [6]. Moreover, there are problems because of bandwidth asymmetry and intermittency of the link. Generally, probing is done in protocols like Peach [26], Peach+ [21], TP-