Transport protocols for multi hop wireless networks

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A taxonomy of the parameters used by decision methods for adaptive video transmission

International audienceNowadays, video data transfers account for much of the Internet traffic and a huge number of users use this service on a daily base. Even if videos are usually stored in several bitrates on servers, the video sending rate does not take into account network conditions which are changing dynamically during transmission. Therefore, the best bitrate is not used which causes sub-optimal video quality when the video bitrate is under the available bandwidth or packet loss when it is over it. One solution is to deploy adaptive video, which adapts video parameters such as bitrate or frame resolution to network conditions. Many ideas are proposed in the literature, yet no paper provides a global view on adaptation methods in order to classify them. This article fills this gap by discussing several adaptation methods through a taxonomy of the parameters used for adaptation. We show that, in the research community, the sender generally takes the decision of adaptation whereas in the solutions supported by major current companies the receiver takes this decision. We notably suggest, without evaluation, a valuable and realistic adaptation method, gathering the advantages of the presented methods

ResTP: A Configurable and Adaptable Multipath Transport Protocol for Future Internet Resilience

Motivated by the shortcomings of common transport protocols, e.g., TCP, UDP, and MPTCP, in modern networking and the belief that a general-purpose transport-layer protocol, which can operate efficiently over diverse network environments while being able to provide desired services for various application types, we design a new transport protocol, ResTP. The rapid advancement of networking technology and use paradigms is continually supporting new applications. The configurable and adaptable multipath-capable ResTP is not only distinct from the standard protocols by its flexibility in satisfying the requirements of different traffic classes considering the characteristics of the underlying networks, but by its emphasis on providing resilience. Resilience is an essential property that is unfortunately missing in the current Internet. In this dissertation, we present the design of ResTP, including the services that it supports and the set of algorithms that implement each service. We also discuss our modular implementation of ResTP in the open-source network simulator ns-3. Finally, the protocol is simulated under various network scenarios, and the results are analyzed in comparison with conventional protocols such as TCP, UDP, and MPTCP to demonstrate that ResTP is a promising new transport-layer protocol providing resilience in the Future Internet (FI)

Effect of multiple simultaneous HSDPA users on HSDPA end-user performance for non-real time services in one cell system

HSDPA networks are currently being deployed; however, there is little knowledge about how these networks perform and behave, and which will the Quality of Service and Quality of Experience that users will achieve due to the fact that UEs share the downlink channel. Furthermore, HSDPA planning and dimensioning is being done through the traditional mechanisms to plan and dimension UMTS networks. These mechanisms do not provide, though, accurate results for HSDPA. This thesis will focus on doing progress in these two areas. A HSDPA simulator was built to find some answers. This simulator used a simplistic model to simulate the radio environment and HSDPA features at Node B. Besides, the simulator dynamically created web browsing traffic according to the traffic patterns specified by the 3GPP. Three main simulations were performed. First, the maximum number of HSDPA users that a HSDPA network can support was obtained for different mean cell throughputs. Results also showed that the relationship between the mean cell throughput and the maximum number of users is linear. Second, the effect of the amount of UEs in a HSDPA network was studied. Results showed how the network and end-user performance changed when the number of UEs differed from the maximum number of UEs. Simulations demonstrated that network and end-user performance decreases rapidly and significantly when the maximum number of UEs was exceeded. Finally, the mean session inter-arrival time was modified to observe how this traffic parameter affected the network and the end-user performance. Furthermore, different sets of number of UEs were used to find out any correlation between the number of UEs and the mean session inter-arrival time. Results showed how the mean session inter-arrival time was much more relevant for the network and end-user performance when the maximum number of UEs had been exceeded. Results will give a glimpse of how HSDPA can perform in real networks. Besides, this simulator can help operators and providers to plan and dimension HSDPA networks more accurately