18,729 research outputs found
SatERN: a PEP-less solution for satellite communications
In networks with very large delay like satellite IPbased
networks, standard TCP is unable to correctly grab the
available resources. To overcome this problem, Performance Enhancing Proxies (PEPs), which break the end-to-end connection and simulate a receiver close enough to the sender, can be placed before the links with large delay. Although splitting PEPs does not modify the transport protocol at the end nodes, they prevent the use of security protocols such as IPsec. In this paper, we propose solutions to replace the use of PEPs named SatERN. This
proposal, based on Explicit Rate Notification (ERN) protocols over IP, does not split connections and is compliant with IP-in-IP tunneling solutions. Finally, we show that the SatERN solution achieves high satellite link utilization and fairness of the satellite traffic
Proactive TCP mechanism to improve Handover performance in Mobile Satellite and Terrestrial Networks
Emerging standardization of Geo Mobile Radio (GMR-1) for satellite system is
having strong resemblance to terrestrial GSM (Global System for Mobile
communications) at the upper protocol layers and TCP (Transmission Control
Protocol) is one of them. This space segment technology as well as terrestrial
technology, is characterized by periodic variations in communication properties
and coverage causing the termination of ongoing call as connections of Mobile
Nodes (MN) alter stochastically. Although provisions are made to provide
efficient communication infrastructure this hybrid space and terrestrial
networks must ensure the end-to-end network performance so that MN can move
seamlessly among these networks. However from connectivity point of view
current TCP performance has not been engineered for mobility events in
multi-radio MN. Traditionally, TCP has applied a set of congestion control
algorithms (slow-start, congestion avoidance, fast retransmit, fast recovery)
to probe the currently available bandwidth on the connection path. These
algorithms need several round-trip times to find the correct transmission rate
(i.e. congestion window), and adapt to sudden changes connectivity due to
handover. While there are protocols to maintain the connection continuity on
mobility events, such as Mobile IP (MIP) and Host Identity Protocol (HIP), TCP
performance engineering has had less attention. TCP is implemented as a
separate component in an operating system, and is therefore often unaware of
the mobility events or the nature of multi-radios' communication. This paper
aims to improve TCP communication performance in Mobile satellite and
terrestrial networks.Comment: 5 pages, 2 figure
Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View
Small satellite systems enable whole new class of missions for navigation,
communications, remote sensing and scientific research for both civilian and
military purposes. As individual spacecraft are limited by the size, mass and
power constraints, mass-produced small satellites in large constellations or
clusters could be useful in many science missions such as gravity mapping,
tracking of forest fires, finding water resources, etc. Constellation of
satellites provide improved spatial and temporal resolution of the target.
Small satellite constellations contribute innovative applications by replacing
a single asset with several very capable spacecraft which opens the door to new
applications. With increasing levels of autonomy, there will be a need for
remote communication networks to enable communication between spacecraft. These
space based networks will need to configure and maintain dynamic routes, manage
intermediate nodes, and reconfigure themselves to achieve mission objectives.
Hence, inter-satellite communication is a key aspect when satellites fly in
formation. In this paper, we present the various researches being conducted in
the small satellite community for implementing inter-satellite communications
based on the Open System Interconnection (OSI) model. This paper also reviews
the various design parameters applicable to the first three layers of the OSI
model, i.e., physical, data link and network layer. Based on the survey, we
also present a comprehensive list of design parameters useful for achieving
inter-satellite communications for multiple small satellite missions. Specific
topics include proposed solutions for some of the challenges faced by small
satellite systems, enabling operations using a network of small satellites, and
some examples of small satellite missions involving formation flying aspects.Comment: 51 pages, 21 Figures, 11 Tables, accepted in IEEE Communications
Surveys and Tutorial
A cross-layer approach to enhance QoS for multimedia applications over satellite
The need for on-demand QoS support for communications over satellite is of primary importance for distributed multimedia applications. This is particularly true for the return link which is often a bottleneck due to the large set of end-users accessing a very limited uplink resource. Facing this need, Demand Assignment Multiple Access (DAMA) is a classical technique that allows satellite operators to offer various types of services, while managing the resources of the satellite system efficiently. Tackling the quality degradation and delay accumulation issues that can result from the use of these techniques, this paper proposes an instantiation of the Application Layer Framing (ALF) approach, using a cross-layer interpreter(xQoS-Interpreter). The information provided by this interpreter is used to manage the resource provided to a terminal by the satellite system in order to improve the quality of multimedia presentations from the end users point of view. Several experiments are carried out for different loads on the return link. Their impact on QoS is measured through different application as well as network level metrics
Optical network technologies for future digital cinema
Digital technology has transformed the information flow and support infrastructure for numerous application domains, such as cellular communications. Cinematography, traditionally, a film based medium, has embraced digital technology leading to innovative transformations in its work flow. Digital cinema supports transmission of high resolution content enabled by the latest advancements in optical communications and video compression. In this paper we provide a survey of the optical network technologies for supporting this bandwidth intensive traffic class. We also highlight the significance and benefits of the state of the art in optical technologies that support the digital cinema work flow
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