The Past, Present, and Future of Transport-Layer Multipath

Multipathing in communication networks is gaining momentum due to its attractive features of increased reliability, throughput, fault tolerance, and load balancing capabilities. In particular, wireless environments and datacenters are envisioned to become largely dependent on the power of multipathing for seamless handovers, virtual machine (VM) migration and in general, pooling less proficient resources together for achieving overall high proficiency. The transport layer, with its knowledge about end-to-end path characteristics, is well placed to enhance performance through better utilization of multiple paths. Realizing the importance of transport-layer multipath, this paper investigates the modernization of traditional connection establishment, flow control, sequence number splitting, acknowledgement, and flow scheduling mechanisms for use with multiple paths. Since congestion control defines a fundamental feature of the transport layer, we study the working of multipath rate control and analyze its stability and convergence. We also discuss how various multipath congestion control algorithms differ in their window increase and decrease functions, their TCP-friendliness, and responsiveness. To the best of our knowledge, this is the first in-depth survey paper that has chronicled the evolution of the transport layer of the Internet from the traditional single-path TCP to the recent development of the modern multipath TCP (MPTCP) protocol. Along with describing the history of this evolution, we also highlight in this paper the remaining challenges and research issues

A Holistic Survey of Wireless Multipath Video Streaming

Most of today's mobile devices are equipped with multiple network interfaces and one of the main bandwidth-hungry applications that would benefit from multipath communications is wireless video streaming. However, most of current transport protocols do not match the requirements of video streaming applications or are not designed to address relevant issues, such as delay constraints, networks heterogeneity, and head-of-line blocking issues. This article provides a holistic survey of multipath wireless video streaming, shedding light on the different alternatives from an end-to-end layered stack perspective, unveiling trade-offs of each approach and presenting a suitable taxonomy to classify the state-of-the-art. Finally, we discuss open issues and avenues for future work.Comment: 42 pages. 13 figures. 9 Tables. Accepted for publication in IEEE Communications Surveys and Tutorials, 201