SDN in wireless environments. Role of satellite systems & MPTCP

In recent years, we have witnessed the growth of smart devices and an ever-increasing number of wireless users. This gives a good opportunity for a variety of bandwidth intensive multimedia applications such as video streaming, online gaming, and high deffinition television. It is forecasted that they will drive an 800 percent increase in mobile data traffic during the next five years according to Cisco's latest report. To meet the high bandwidth demand, one of the visions of future mobile system is the integration of different radio access technologies to form a heterogeneous wireless network, using for example Wireless Fidelity (Wi-Fi), Long Term Evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX). However, radio resources in the current wireless networks are still scarce. Therefore, it is anticipated that future mobile system will be a denser network comprising more Wi-Fi access points, small cells covering finer areas, and integrating other wireless technologies such as satellite networks. Another trend is the emergence of multihomed mobile devices which are equipped with multiple interfaces such as Wi-Fi and LTE. Currently, satellite interfaces are not widely installed on mobile terminals such as vehicles or smartphones, but will be once the market for satellite networks is opened in the near future. In a heterogeneous wireless network, devices with multi-interface can toggle between different connections and select the one that best suits the applications' demand. Further, it can aggregate the bandwidth of more than one interface on transport layer while presenting a single logical link to the application. Therefore, bandwidth aggregation provides an opportunity to scale up network capacity to meet the high bandwidth demand and enhance quality of service. This thesis discusses the role of a newly emerged technologies Software Desined Networking and Multipath TCP (MPTCP) in future mobile systems specially in satellite networks where they are utilized to boost throughput and handle frequent satellite handovers. The work leaded to two papers under the names of 1) Multipath TCP in SDN-enabled LEO Satellite Networks, and 2) Software Defined Networking for Naval Satellite Communications (SDN-NavSat) which the thesis is mainly written based on them. Satellite systems such as Low Earth Orbiting (LEO) networks play an important role in the next generation 5G networks. To facilitate the integration of satellite and terrestrial networks, software-defined networking (SDN) is embraced which brings flexibility, user-customized services and reduces the cost of network configurations. However, it has been long known that communications via LEO satellite network suffer from long delay and frequent ground-satellite handovers, both are problematic for TCP connections. The emergence of Multipath TCP (MPTCP) provides a new solution to these challenges. In first paper, we study the performance of MPTCP over SDN-enabled LEO satellite networks. MPTCP maintains multiple simultaneous subflows in space to increase throughput. In anticipation of handover, MPTCP creates subflows that run in backup mode and shifts traffic smoothly. To support MPTCP, we design an SDN controller that identifies MPTCP subflows attached to the same MPTCP session and splits them to disjoint paths. The SDN architecture centralizes the routing logic, so the system is more scalable and on-board processing is minimized. Simulations are run to evaluate the proposed MPTCP-SDN framework. It is shown our strategy significantly improves throughput performance and prevents the interruption of transmission during handover, compared to previous solutions. In the second paper, we propose a Software Defined architecture called Software Defined Networking for Naval SATCOM (SDN-NavSat) supports a naval ship fleet using multiple satellite communication systems. It focuses on practical issues in current shipboard naval networks such as sharing multiple satellite communication links and overcoming limited bandwidth constraints. In our proposal, Multipath Transmission Control Protocol (MPTCP) enhances resource sharing by creating several subflows under one TCP session. The management and classification of the subflows handled by a designed SDN controller. The cooperation between MPTCP and SDN controller leads to an agile, bandwidth efficient, robust naval network. Our analysis and numerical evaluation prove the feasibility and efficacy of SDN-based solution for such a network.