SATELLITE AND SPACE COMMUNICATIONS Technical Committee

Satellite broadband systems will play a key role in reducing the Digital Divide by complementing terrestrial networks in the delivery of next generation broadband to users in remote and rural locations. We describe an integrated broadband delivery system to fixed users that makes simultaneous use of different access networks in order to optimise the end-user QoE. The design of the overall network architecture and the key building blocks of the routing entities at both ends of the integrated system are presented. Moreover, we introduce the design of a High Throughput Satellite (HTS) system targeting the 2020 timeframe and envisaging two different configurations for the feeder link using either Q/V or optical gateways, whereas user links are always in Ka-band. INTRODUCTION The research project BATS (Broadband Access via integrated Terrestrial & Satellite systems) [1], co-funded by the European Commission (EC) under the FP7 programme, addresses the delivery of Broadband (BB) future services in Europe according to the EC Digital Agenda [2] objective to reliably deliver >30Mbps to 100% of European households by 2020. Next generation geostationary (GEO) broadband satellite systems will play a key role in achieving such objectives as the accelerated deployment of terrestrial broadband technology will not be able to satisfy this requirement in the most difficult-to-serve locations. The BATS project aims to bridge the potentially widening Broadband divide between urban and rural areas and fulfil the Digital Agenda targets in the underserved areas via an integrated network that combines the flexibility, large coverage and high capacity of future multi-spot beam satellites, the low latency of fixed DSL lines, and the pervasiveness of mobile-wireless access. The integrated broadband service will be delivered to the end-user via an Intelligent User Gateway (IUG) and Intelligent Network Gateway (ING), dynamically routing traffic flows according to their service needs through the most appropriate broadband access network, with the goal of optimizing the user ś Quality of Experience (QoE). In this paper we first present the overall network architecture of the BATS system. We then focus on the building blocks of the two routing entities at both end-points on the network, the IUG and ING. Two different High Throughput Satellite systems are then presented with Q/V-band and Optical feeder link configuration respectively. Finally we conclude the paper with some details on our future work. NETWORK ARCHITECTURE As illustrated in Figure 1 the overall network architecture comprises the three broadband access segments, namely xDSL, cellular and satellite, whose connections are terminated at the IUG on the end-user side and at the ING on the central/operator side. The IUG is the routing entity located at the end-user premises serving as the focal point for the integration of the terrestrial and satellite connections. As the counterpart of the IUG on the network side, the ING has the functionalities of both managing a set of associated IUGs and acting as a single connection interface to the public internet. For the downstream traffic, an ING has equivalent building blocks and routing functionalities to the IUG. The main functionality of IUG and ING is to route the outgoing traffic towards the most suitable access network segment considering the QoE requirements of each particular traffic flow and the real-time status of each of the links. Based on this, the ING shall be located closer to the Point of Presence (PoP) of the terrestrial operators involved in the integrated system, in order not to increase the latency of the services routed terrestrially (which are meant to be the most delay sensitive). In addition, due to TCP performance degradation over satellite links, Performance Enhancement Proxies (PEPs) are currently one of the most commonly adopted solutions to achieve good transport performances whatever the available TCP stack at both ends. For the BATS architecture it has been decided that the best compromise between performance, impact and complexity is to locate a high capacity PEP in a central point of the network near to the PoP or at the ING, alleviating the internal re-routing and synchronization issues compared to a case where the PEP is located at the nominal satellite gateway and traffic needs to be re-routed to a