End-to-End Algebraic Network Coding for Wireless TCP/IP Networks

The Transmission Control Protocol (TCP) was designed to provide reliable transport services in wired networks. In such networks, packet losses mainly occur due to congestion. Hence, TCP was designed to apply congestion avoidance techniques to cope with packet losses. Nowadays, TCP is also utilized in wireless networks where, besides congestion, numerous other reasons for packet losses exist. This results in reduced throughput and increased transmission round-trip time when the state of the wireless channel is bad. We propose a new network layer, that transparently sits below the transport layer and hides non congestion-imposed packet losses from TCP. The network coding in this new layer is based on the well-known class of Maximum Distance Separable (MDS) codes.Comment: Accepted for the 17th International Conference on Telecommunications 2010 (ICT2010), Doha, Qatar, April 4 - 7, 2010. 6 pages, 7 figure

Masking Lossy Networks by TCP Tunnel with Network Coding

Transmission Control Protocol (TCP) with Network Coding (TCP/NC) was designed to recover the lost packets without TCP retransmission to improve the goodput performance in lossy networks. However, TCP/NC is too costly to be implemented in some types of end devices, e.g., with less memory and power. In addition, TCP/NC across loss-free but thin networks may waste scarce link bandwidth due to the redundant combination packets sacrificed for the lossy network. In this paper, we propose the TCP/NC tunnel to convey end-to-end TCP sessions on a single TCP/NC flow traversing a lossy network between two special gateways without per-flow management. We implemented and validated our proposal in Network Simulator 3, in which each gateway runs a reinforced version of TCP/NC that we previously developed. The results show that the proposed TCP/NC tunnel can mitigate the goodput degradation of end-to-end TCP sessions traversing a lossy network without any change in TCP on each end host.The 22nd IEEE Symposium on Computers and Communications (ISCC\u2717), 03 - 06 July 2017, Heraklion, Crete, Greec

TCP Performance Analysis in Dynamic GPRS LA

This paper presents the findings on TCP performance measurements in the LA process during the deployment of GPRS CS1 and CS2 coding schemes and after the activation of two more coding schemes, CS3 and CS4. The measurements are done under various network scenarios based on users’ physical locations in one of Malaysia’s commercially deployed live GPRS networks. End-to-end evaluation of FTP application is used for the assessment together with tracing at the GPRS air interface. The results show that TCP works well in the LA process and can cope with the frequent switching between the coding schemes without any problem. Throughput performance is observed to be stable in all scenarios. The activation of higher coding schemes aided by TCP tuning also proves to be beneficial by the 23% increase in average throughput seen for urban areas

On the Characteristics of TCP/NC Tunneling in Heterogeneous Environments

Transmission Control Protocol (TCP) with a loss-based congestion control is still dominantly used for reliable end-to-end data transfer over diverse types of network although it is ineffective when traversing lossy networks. We previously proposed an IP tunneling system across lossy networks using the TCP with Network Coding (TCP/NC tunnel) and showed its potential to significantly mitigate the goodput degradation of end-to-end TCP sessions without any change of enddevice’s communications protocol stack, but it was shown only in homogeneous conditions. On the other hand, reliable end-to-end data transfer in diverse and heterogeneous IoT environments in a cost-efficient manner is an emerging challenge. Therefore, in this paper, we investigate the characteristics of the TCP/NC tunnel on heterogeneous networks with/without network congestions, to assess the applicability of the TCP/NC tunnel-based intelligent gateway system to IoT environments where end-devices are connected to a gateway with different link bandwidths or connected to different gateways in terms of network topology. The simulation results suggest the TCP/NC tunnel can efficiently utilize the bottleneck bandwidth in such heterogeneous situations even with congestion and achieve a significantly high goodput of end-to-end TCP sessions in a wide range of link loss degree especially when the tunnel link bandwidth is sufficient.The 10th International Conference on Intelligent Networking and Collaborative Systems (INCoS-2018), September 5 - 7, 2018, Comenius University in Bratislava, Slovaki

Dynamic ACK skipping in TCP with Network Coding for Power Line Communication Networks

Transmission Control Protocol (TCP) still plays an essential role in various user applications for end-to-end reliable data transmission. However, TCP cannot get a high goodput performance in the lossy networks because it considers any packet loss to be a congestion signal and decreases the congestion window mistakenly. Therefore, TCP with Network Coding (termed TCP/NC) was proposed to recover the packet loss at the sink without retransmission if the number of coded packets is enough. However, the ACK packet needs to be sent for any arriving coded packet as a feedback of the end-to-end channel condition, resulting in a lower transmission performance in half- duplex networks, e.g., Power Line Communication. Therefore, we propose the ACK-Skipping scheme for TCP/NC to limit the number of ACK packets but still retain the necessary information, e.g., for channel estimation. The simulation result on ns-3 (Network Simulation 3) shows that the proposal achieves a higher goodput on PLC environment compared to TCP with Selective Acknowledgment and TCP Westwood+ as well as the recent variant of TCP/NC.The 22nd International Conference on Advanced Communications Technology, ICACT2020, 16-19 February 2020, Phoenix Park, PyeongChang, Kore

Effective Retransmission in Network Coding for TCP

Incorporating network coding into TCP has the advantage of masking packet losses from the congestion control algorithm. It could make a lossy channel appear as a lossless channel for TCP, therefore the transport protocol can only focus on handling congestion. However, most schemes do not consider the decoding delay, thus are not suitable to be implemented in practical systems. We propose a novel feedback based network coding (FNC) retransmission scheme which has high throughput and quite low decoding delay without sacrificing throughput. It uses the implicit information of the seen scheme to acquire the exact number of packets the receiver needs for decoding all packets based on feedback. We also change the encoding rules of retransmission, so as to decode part of packets in advance. The scheme can work well on handling not only random losses but also bursty losses. Our scheme also keeps the end-to-end philosophy of TCP that the coding operations are only performed at the end hosts. Thus it is easier to be implemented in practical systems. Simulation results show that our scheme significantly outperforms the previous coding approach in reducing decoding delay, and obtains the throughput which is close to the scenarios where there is zero error loss. It is particularly useful for streaming applications

ANALISIS PERBANDINGAN PERFORMANSI VARIAN TCP PADA JARINGAN HSDPA

ABSTRAKSI: HSDPA menambahkan beberapa teknik baru pada implementasinya yang dapat menyediakan layanan lebih cepat daripada UMTS yaitu, fast link adaptation, HARQ (Hybrid Auto Repeat Request), dan AMC (Adaptive Modulation and Coding). HSDPA juga memperkenalkan distributed architecture yang lebih baik pada node-B (base station) untuk menangani transfer data sehingga dapat menangani fast scheduling dan fast retransmission. Layanan data dalam HSDPA menggunakan TCP sebagai protokol transport-nya.Awalnya TCP didesain untuk media kabel, tetapi pada HSDPA terdapat media udara yang bersifat tidak stabil. Berbagai macam variasi TCP dibuat untuk menghasilkan performansi yang lebih baik dari pendahulunya. Dalam tugas akhir ini dibandingkan performansi TCP New Reno dan TCP Vegas pada jaringan HSDPA dengan menvariasikan window (5, 10, 15, 20, 25, dan 30) dan packet size (500, 750, 1000, 1250 dan 1500). Performansi TCP dilihat dari segi throughput, packet loss, dan end to end delay-nya.Hasil yang didapatkan dalam simulasi ini adalah TCP Vegas mempunyai performansi yang lebih bagus dari pada TCP New Reno, TCP Vegas menghasilkan throughput yang lebih besar, packet loss yang lebih kecil, dan delay yang lebih kecil. Tetapi dengan meningkatkan error model yang menyebabkan packet loss lebih besar, TCP New Reno dapat menunjukkan performansi yang lebih baik dibandingkan TCP VegasKata Kunci : HSDPA, TCP New Reno, TCP Vegas,ABSTRACT: HSDPA adds several new techniques in its implementation that can provide faster service than UMTS, which are fast link adaptation, HARQ (Hybrid Auto Repeat Request), and AMC (Adaptive Modulation and Coding). HSDPA also introduces better distributed architecture in the node-B (base station) for handling data transfer so that it can handle fast scheduling and fast retransmission. Data service in HSDPA uses TCP as its transport protocol.At the beginning, TCP was designed for wired media, but at HSDPA there is air medium which is not stable. Various kinds of TCP variations are made to produce better performance than its predecessor. In this final project, performance of TCP New Reno and TCP Vegas are compared in HSDPA network by varying the windows (5, 10, 15, 20, 25, and 30) and packet sizes (500, 750, 1000, 1250, and 1500). TCP performance is seen in terms of its throughput, packet loss, and end to end delay.Results obtained in this simulation are TCP Vegas has a better performance than TCP New Reno, TCP Vegas produces greater throughput, smaller pocket loss, and smaller delay than TCP New Reno does. But by increasing error model that causes bigger packet loss, TCP New Reno can show better performance than TCP Vegas does.Keyword: HSDPA, TCP New Reno, TCP Vega

Making H-ARQ suitable for a mobile TCP receiver over LEO satellite constellations

This paper investigates strategies to carry out delay tolerant services over LEO satellite constellations for mobile receiver. In this context, LEO constellations are characterized by important delay variations where propagation impairments are mostly localized on the Land Mobile Satellite (LMS) channel (i.e. on the last hop). To cope with this issue, distinct reliability schemes can be introduced at the physical or link layers. Although their capacity to cope with transmission errors has been demonstrated, these recovery schemes may induce a high jitter that could severely damage TCP's internal timers and reliability schemes. As a matter of fact, transport and link layers’ reliability schemes exhibit a clear discrepancy. Following temporal traces representing the delay between a mobile terminal and the last hop satellite from a LEO constellation, we assess how HARQ mechanisms impact on the RTO based retransmission and the duplicate acknowledgments of TCP. Based on ns-2 simulations, we propose a layer-2 buffer that let both link and transport layers to conjointly perform. Our evaluations show an end-to-end data rate increase and more generally illustrate the benefit of re-ordering packets at the link layer when link-layer erasure coding recovery mechanisms are used conjointly with TCP

Network Coded TCP (CTCP) Performance over Satellite Networks

We show preliminary results for the performance of Network Coded TCP (CTCP) over large latency networks. While CTCP performs very well in networks with relatively short RTT, the slow-start mechanism currently employed does not adequately fill the available bandwidth when the RTT is large. Regardless, we show that CTCP still outperforms current TCP variants (i.e., Cubic TCP and Hybla TCP) for high packet loss rates (e.g., >2.5%). We then explore the possibility of a modified congestion control mechanism based off of H-TCP that opens the congestion window quickly to overcome the challenges of large latency networks. Preliminary results are provided that show the combination of network coding with an appropriate congestion control algorithm can provide gains on the order of 20 times that of existing TCP variants. Finally, we provide a discussion of the future work needed to increase CTCP's performance in these networks.Comment: 4 pages, 4 figures, Accepted at SPACOMM 201