Population Based Routing in LEO Satellite Networks

Packet switching in a Low Earth Orbit (LEO) satellite network may calculate the best traffic route through the less populated areas of the planet, in order to avoid relaying through the busiest satellites. A number of ideas for route calculation in a LEO system have been evaluated and the performance results are presented. This paper reports from ongoing research on Space Information Networks (SIN) with the purpose to offer application services in a LEO satellite network to mobile users. The conclusion is that route calculation based on population density gives a moderate, but significant improvement in resource utilization.publishedVersio

Cooperative Caching in Space Information Networks

publishedVersio

Resilient internetwork routing over heterogeneous mobile military networks

Mobile networks in the military tactical domain, include a range of radio networks with very diverse characteristics and which may be employed differently from operation to operation. When interconnecting networks with dissimilar characteristics (e.g. capacity, range, mobility) a difficult trade-off is to fully utilize the diverse network characteristics while minimizing the cost. To support the ever increasing requirements for future operations it is necessary to provide tools to quickly alter the rule-set during an ongoing operation, due to a change in operation and/or to support different needs. Our contribution is a routing protocol which targets these challenges. We propose an architecture to connect networks with different characteristics. One key point is that low capacity links/networks segments can be included in the heterogeneous network, these segments are protected from overload by controlling where and when signaling/data traffic is sent. The protocol supports traffic policing, including resource reservation. The other key point is the ability to quickly alter the network policy (rules-set) including QoS support during an operation or from operation to operation.author postprin

Selected Issues of QoS Provision in Heterogenous Military Networks

Tactical ad-hoc networks are evolving today towards complex heterogeneous networks in terms of architecture, protocols and security. Due to the difference in network resources and reliability, end-to-end quality of service provisioning becomes very challenging. If we also take into account communication issues such as unpredictable connectivity, preferential forwarding for special traffic classes, intermittency due to node or communication link failure, the problem is further aggravated.In this article, we examine the major challenges that must be solved in order to provide efficient QoS provisioning in the heterogeneous network. Finally we describe QoS-aware mechanisms for inter-domain and intra-domain heterogeneous networks, also including real-time services provision in highly mobile environments.

The dynamics of tethers and space-webs

The thesis 'The dynamics of tethers and space-webs' investigates the motion of the Motorized Momentum Exchange Tether (MMET) on an inclined orbit, and while deploying and retracting symmetric payloads. The MMET system is used as a basis for examining the stability of space-webs using a triangular structure of tethers while rotating. The motion of small robots is introduced as they move on the space-web, and their motions are found to influence the behaviour of the structure. Several methods of limiting the destabilising influences of the robots are considered, and are found to stabilise the web in most circumstances. A structured method for describing the rotations of a tether system is outlined, and different rotational systems are compared. This lays the foundation for the further chapters examining MMET dynamics on an inclined orbit and while deploying and recovering the payloads. Lagrange's equations are generated for the three cases, and are solved using standard numerical integration techniques. To emphasise the practical uses of the MMET system, several missions are analysed by using the system as a re-usable launcher for micro-satellite payloads.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Cooperative Caching in Space Information Networks

publishedVersio

Population Based Routing in LEO Satellite Networks

Packet switching in a Low Earth Orbit (LEO) satellite network may calculate the best traffic route through the less populated areas of the planet, in order to avoid relaying through the busiest satellites. A number of ideas for route calculation in a LEO system have been evaluated and the performance results are presented. This paper reports from ongoing research on Space Information Networks (SIN) with the purpose to offer application services in a LEO satellite network to mobile users. The conclusion is that route calculation based on population density gives a moderate, but significant improvement in resource utilization

Field trials of two 802.11 residual bandwidth estimation methods

Ad hoc networks have attracted much attention due to their decentralized architecture and potential mobility. The latter promise has sparked research aimed towards routing and quality of service (QoS) admission schemes. The volatile links that are inherent to these networks have however spawned a need for a cross-layering service below IP for local route and QoS decision making, or information dissemination to participating hosts. We have conducted field trials of an active and a passive estimation method implemented in a real wireless driver to estimate the residual bandwidth. Through these tess we show how residual bandwidth estimates can be obtained in an 802.11 wireless network and identify the strenghts and weaknesses of their underlying methods. The implemented wireless driver collects per link bandwidth data, local retransmission count and expected transmission tim

Field trials of two 802.11 residual bandwidth estimation methods

Ad hoc networks have attracted much attention due to their decentralized architecture and potential mobility. The latter promise has sparked research aimed towards routing and quality of service (QoS) admission schemes. The volatile links that are inherent to these networks have however spawned a need for a cross-layering service below IP for local route and QoS decision making, or information dissemination to participating hosts. We have conducted field trials of an active and a passive estimation method implemented in a real wireless driver to estimate the residual bandwidth. Through these tess we show how residual bandwidth estimates can be obtained in an 802.11 wireless network and identify the strenghts and weaknesses of their underlying methods. The implemented wireless driver collects per link bandwidth data, local retransmission count and expected transmission tim