Comparative Study on the Performance of TCP-Freeze and TCP-Newreno Over Divert Failure Routing Protocol

Many enhancements have been proposed to address TCP throughput issues over wireless links. In this project, we will study the performance of the standard TCP over TCP Freeze with Divert Route Failure Protocol as the routing mechanism. This study is aimed for the purpose of further improvement in related services provided by TCP over the wireless links. Such enhancements are needed due to the high transmission error rates in wireless links

A User-level, Reliable and Reconfigurable Transport Layer Protocol

Over the past 15 years, the Internet has proven itself to be one of the most influential inventions that humankind has ever conceived. The success of the Internet can be largely attributed to its stability and ease of access. Among the various pieces of technologies that constitute the Internet, TCP/IP can be regarded as the cornerstone to the Internet’s impressive scalability and stability. Many researchers have been and are currently actively engaged in the studies on the optimization of TCP’s performance in various network environments. This thesis presents an alternative transport layer protocol called RRTP, which is designed to provide reliable transport layer services to software applications. The motivation for this work comes from the fact that the most commonly used versions of TCP perform unsatisfactorily when they are deployed over non-conventional network platforms such as cellular/wireless, satellite, and long fat pipe networks. These non-conventional networks usually have higher network latency and link failure rate as compared with the conventional wired networks and the classic versions of TCP are unable to adapt to these characteristics. This thesis attempts to address this problem by introducing a user-level, reliable, and reconfigurable transport layer protocol that runs on top of UDP and appropriately tends to the characteristics of non-conventional networks that TCP by default ignores. A novel aspect of RRTP lies in identifying three key characteristic parameters of a network to optimize its performance. The single most important contribution of this work is its empirical demonstration of the fact that parameter-based, user-configurable, flow-control and congestion-control algorithms are highly effective at adapting to and fully utilizing various networks. This fact is demonstrated through experiments designed to benchmark the performance of RRTP against that of TCP on simulated as well as real-life networks. The experimental results indicate that the performance of RRTP consistently match and exceed TCP’s performance on all major network platforms. This leads to the conclusion that a user-level, reliable, and reconfigurable transport-layer protocol, which possesses the essential characteristics of RRTP, would serve as a viable replacement for TCP over today’s heterogeneous network platforms

A Model for Behavioral Tendency of TCP Congestion Control Variants in LTE Cellular and 802.11ac Networks

As a reliable protocol, TCP protocol configuration requires many parameters to be set before the actual packet transmissions happen. However, the TCP parameters need to be changed from the initial fixed default values to suit the network requirements since it is utilized on many dissimilar mobile networks, including the LTE cellular and the 802.11ac. On the other hand, LTE cellular and 802.11ac networks also have their own design parameters. In this case, utilizing the TCP in these networks will result in the TCP parameters to interact with LTE and 802.11ac parameters, which subsequently can optimize or degrade the network performance due to correct or poor parameters setting. Therefore, it is highly important to determine the correct values for both protocol parameters and network parameters to achieve optimal network performance. This work presents a model to determine the interaction between the TCP protocol parameters, including the congestion control variants and the size of packets and network parameters that include RLC modes in LTE and A-MPDU aggregation mechanism in 802.11ac. Drawn from an extensive set of scenarios and experiments, the results show significant performance improvements achieved by the verified matching parameters

Simulation and Evaluation of Wired and Wireless Networks with NS2, NS3 and OMNET++

Communication systems are emerging rapidly with the revolutionary growth in terms of networking protocols, wired and wireless technologies, user applications and other IEEE standards. Numbers of industrial as well as academic organizations around the globe are bringing in light new innovations and ideas in the field of communication systems. These innovations and ideas require intense evaluation at initial phases of development with the use of real systems in place. Usually the real systems are expensive and not affordable for the evaluation. In this case, network simulators provide a complete cost-effective testbed for the simulation and evaluation of the underlined innovations and ideas. In past, numerous studies were conducted for the performance evaluation of network simulators based on CPU and memory utilization. However, performance evaluation based on other metrics such as congestion window, throughput, delay, packet delivery ratio and packet loss ratio was not conducted intensively. In this thesis, network simulators such as NS2, NS3 and OMNET++ will be evaluated and compared for wired and wireless networks based on congestion window, throughput, delay, packet delivery and packet loss ratio. In the theoretical part, information will be provided about the wired and wireless networks and mathematical interpretation of various components used for these networks. Furthermore, technical details about the network simulators will be presented including architectural design, programming languages and platform libraries. Advantages and disadvantages of these network simulators will also be highlighted. In the last part, the details about the experiments and analysis conducted for wired and wireless networks will be provided. At the end, findings will be concluded and future prospects of the study will be advised.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format