TCP Performs Research Articles

A Cross-Layer Solution for Contention Control to Enhance TCP Performance in Wireless Ad-Hoc Networks

With the development of wireless technology, users not only have wireless access to the Internet, but this has also sparked the emergence of Wireless Ad-hoc Networks (WANETs); this promising networking paradigm has the potential to adopt the shape of new emergent networks such as the Internet of Things (IoT), Vehicular Ad-hoc Networks (VANET) and Wireless Sensor Networks (WSN). However, channel contention (CC) is one of the key reasons why the TCP performs poorly in WANETs. This paper presents a mechanism called Cross-layer Solution for Contention Control (CSCC) to enhance TCP performance in WANETs. Each node starts marking packets in the proposed mechanism when its CC level reaches a certain threshold. As a result, the source node adjusts the congestion window (cwnd) size to a good state to control the insertion ratio of packets into the network. To provide a fair share to each flow, the flow having a large cwnd is penalized more. Numerous simulations have been conducted across several topologies to clarify the performance of the suggested mechanism. The simulation findings show that, in the presence of the Ad-hoc On-demand Distance Vector (AODV) routing and Dynamic Source Routing (DSR) protocols, the proposed CSCC mechanism outperformed TCP NewReno in terms of throughput and fairness. In comparison to TCP NewReno, the suggested mechanism has fewer retransmitted packets.

Performance Evaluation of TCP and UDP Protocols under EPLAODV Rout- ing Protocol in Emergency Situations

Mobile ad hoc networks (MANETs) can easily be deployed in a disastrous situation. Mobile routing protocols provide efficient routing strategies in such situations to share critical and emergency-related information. Many researchers have designed various energy and link-aware routing protocols but research still needs improvement. This study focuses on and evaluates the performance of TCP and UDP transport layer protocols under the EPLAODV routing protocol in an emergency. Various emergency-related scenarios are designed and simulated in the NS-2 environment. Network traffic load, node mobility, and simulation time are the main parameters. It is observed from the results that the TCP performs better than UDP under EPLAODV in an emergency situation.

Improving TCP Performance over Mobile Ad Hoc Networks with an Adaptive Backoff and Response approach (Dept.E)

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TCP and UDP-based performance evaluation of proactive and reactive routing protocols using mobility models in MANETS

User datagram protocol UDP and transmission control protocol TCP are two popular transport layer protocols in infrastructure networks. The behaviour of these transport layer protocol with different mobility models and routing protocols is still not very clear. In this article, we have compared the performance of user datagram protocol UDP and transmission control protocol TCP in mobile ad hoc network MANET for optimised link state routing OLSR, and temporarily ordered routing algorithm TORA routing protocols with different mobility models like random waypoint, reference point group, and Manhattan mobility models. We have done simulations in NS2 to analyse results using the performance metrics, such as throughput, packet delivery ratio, and end-to-end delay by for different types of data traffic and mobility models. The MANET performance is analysed under the effect of simulation time, number of nodes, and speed of mobile nodes. Our work indicates that TCP performs well for throughput in some mobility model and different routing protocols than UDP. The results presented in this paper clearly indicate that the different protocols behave differently under different parameters.

Adaptive Network Coding Scheme for TCP over Wireless Sensor Networks

The purpose of this paper is to develop a network coding scheme to enhance TCP performance in wireless sensor networks. It is well known that TCP performs poorly over wireless links which suffer from packet losses mainly due to the bad channel. To address this problem, it is useful to incorporate network coding into TCP, as network coding can offer significant benefits in terms of throughput, reliability, and robustness. However, the encoding and decoding operations of network coding techniques will bring an additional delay that has a negative effect on applications of wireless sensor networks. In this paper, we propose an adaptive network coding (ANC) scheme which contains two major aspects: the adjustment of the redundancy factor R and the adjustment of the coding window size CW. We dynamically adjust these two parameters depending on the measured packet loss rate, so that the proposed ANC can effectively mask packet losses and reduce the decoding delay of network coding. The performance of our scheme is evaluated by simulations using NS-2 simulator. Compared to other schemes, the ANC not only achieves a good throughput but also has the lowest average delay and the lowest maximum delay in all experimental environments.

Decision of Maximum Congestion Window Size for TCP Performance Improvement by Bandwidth and RTT Measurement in Wireless Multi-Hop Networks

In the wireless network, TCP performs poorly because it was originally designed for wired networks and does not take into consideration wireless characteristics such as mobility, high-loss probability, and hidden-terminal problems. In particular, in the wireless multi-hop networks, a large congestion window increases the probability of contention and packet losses, and TCP performance is degraded severely as a result. So, it is necessary to limit the TCP congestion window size in order keep the probability of contention loss in the system to a minimum. In this paper, we propose a new scheme for determining the maximum congestion window size based on the measured bandwidth and Round- Trip-Time (RTT). Using ns-2 simulation, we show that the proposed scheme reduces the probability of packet contention and improves TCP performance.

TCP performance over mobile ad hoc networks

TCP is a transport protocol that guarantees reliable ordered delivery of data packets over wired networks. Although it is well tuned for wired networks, TCP performs poorly in mobile ad hoc networks (MANETs). This is because TCP's implicit assumption that any packet loss is due to congestion is invalid in mobile ad hoc networks where wireless channel errors, link contention, mobility and multipath routing may significantly corrupt or disorder packet delivery. If TCP misinterprets such losses as congestion and consequently invokes congestion control procedures, it will suffer from performance degradation and unfairness. To understand TCP behaviour and improve the TCP performance over multi-hop ad hoc networks, considerable research has been carried out. As the research in this area is still active and many problems are still wide open, an in-depth and timely survey is needed. In this paper, the challenges imposed on the standard TCP in the wireless ad hoc network environment are first identified. Then some existing solutions are discussed according to their design philosophy. Finally, some suggestions regarding future research issues are presented.

Evaluation of TCP and Internet traffic via low Earth orbit satellites

The prospect of the Internet as the fastest growing satellite communication application coupled with satellite-based multimedia networks has generated a high level of interest in the performance of TCP over satellite systems. This article presents the network architecture for supporting services based on TCP/IP over satellite. It discusses the key factors that influence TCP performance over satellite links, and compares the benefits and disadvantages of low Earth orbit and geostationary Earth orbit satellite. The article also discusses the feasibility of using LEO satellites to support and expand the Internet. It presents studies of the TCP behavior over a GEO satellite system and LEO satellite constellation based on computer simulations, where two typical Internet applications are taken into consideration: FTP file transfer and Web browsing. The results show that TCP performs much better over the LEO satellite constellation than over the GEO system; even the standard TCP over LEO is better than enhanced TCP over GEO.