Resource Management for Broadband Satellite Networks

Purdue University, West Lafayette IN

Investigators

Abstract

Broadband satellite systems have an important role to play in the delivery of multimedia applications. In this proposal we concentrate on GEO (geo-synchronous) based satellite networks. GEO based systems deliver continuous services to a specific region with a single satellite. They play an ever-increasing role in the public and private Internets, due mostly to their large geographic coverage, inherent broadcast capabilities and fast deployment. They are attractive to support data, audio and video streaming; bulk data transfer such as software updates or dissemination of Web caches; and applications involving limited interactivity such as distance learning. They are also attractive to provide broadband access to users who are either beyond the reach of the terrestrial network, or have particular needs for broadcast/multicast applications or fast deployment. We will focus in this proposal on Next Generation Satellite Networks that comprise one (or more) GEO satellite with some form of onboard processing (OBP). Two of the essential issues regarding broadband satellite network are 1) end-to-end resource management, and 2) network availability. Resource management is key to deliver acceptable Quality of Service (QoS) to services while providing adequate efficiency. It is central to any satellite system, be it a bent pipe or an onboard processing (OBP) satellite system. Indeed, in order to offer flexibility and efficiency to bursty applications, the capacity of the multiple access uplink has to be managed using some bandwidth on demand (BoD) scheme. We define network availability as the ability for the network to offer some level of services to some applications even during degraded periods. Most of the next generation systems will be using the Ka band, which is known for its very difficult transmission characteristics. Many solutions involving variable rate coding, power control, and/or variable modulation have been proposed to make this band friendly to broadband applications. This proposal will not study directly those layer 1/2 mechanisms but rather study how their use affects BoD and more generally end-to-end resource management. Hence the final objective of our proposal is to design and evaluate end-to-end resource management for the Next Generation of Satellite Networks that interworks efficiently with the range of solutions proposed by the air-interface designer to improve the availability of the transmission. In particular, we want to understand the trade-off in terms of efficiency and system complexity. To achieve this ultimate objective, we will study: 1. Static end-to-end resource management for large GEO OBP systems. The term static refers to the fact that the coding and modulation are fixed. The focus here will be to develop and evaluate mechanisms that are scalable, robust, flexible and protect the OBP (i.e., the switch in the sky). We will build upon our extensive previous work in the domain where we developed scalable, robust, flexible end-to-end resource management for large GEO bent pipe systems. 2. Network availability. One of the main concerns of satellite network designers is to offer an "appropriate" level of service to the users in spite of the difficult characteristics of the frequency band. However it is not very clear what is meant by "an appropriate level of service" since it may vary from a user to another or from an application to another. Most of the studies have focussed on link availability without taking into account the networking and applications aspects. We believe that coordinating the lower layers with the upper layers will give us a flexible and cost-efficient solution allowing the system to deliver different levels of network availability to the users depending on their need and their willingness to pay. Hence network availability can be seen as a QoS requirement and should be defined and studied that way. 3. Designing end-to-end resource management for a system comprising layer 1/2 mechanisms to dynamically improve the uplink availability so as to offer flexible and cost efficient services to the users. We need to propose solutions and to evaluate them to ensure that the increase in complexity is worthwhile in terms of efficiency. We will also propose and study some dynamic pricing schemes integrated with the BoD so as to allow the users to indicate their willingness to pay for capacity in a context where the total available capacity is variable due to link impairment.