Quality of Service over Specific Link Layers: state of the art report

The Integrated Services concept is proposed as an enhancement to the current Internet architecture, to provide a better Quality of Service (QoS) than that provided by the traditional Best-Effort service. The features of the Integrated Services are explained in this report. To support Integrated Services, certain requirements are posed on the underlying link layer. These requirements are studied by the Integrated Services over Specific Link Layers (ISSLL) IETF working group. The status of this ongoing research is reported in this document. To be more specific, the solutions to provide Integrated Services over ATM, IEEE 802 LAN technologies and low-bitrate links are evaluated in detail. The ISSLL working group has not yet studied the requirements, that are posed on the underlying link layer, when this link layer is wireless. Therefore, this state of the art report is extended with an identification of the requirements that are posed on the underlying wireless link, to provide differentiated Quality of Service

Spacelab system analysis: A study of the Marshall Avionics System Testbed (MAST)

An analysis of the Marshall Avionics Systems Testbed (MAST) communications requirements is presented. The average offered load for typical nodes is estimated. Suitable local area networks are determined

Spacelab system analysis: A study of communications systems for advanced launch systems

An analysis of the required performance of internal avionics data bases for future launch vehicles is presented. Suitable local area networks that can service these requirements are determined

Integration of the White Sands Complex into a Wide Area Network

The NASA White Sands Complex (WSC) satellite communications facility consists of two main ground stations, an auxiliary ground station, a technical support facility, and a power plant building located on White Sands Missile Range. When constructed, terrestrial communication access to these facilities was limited to copper telephone circuits. There was no local or wide area communications network capability. This project incorporated a baseband local area network (LAN) topology at WSC and connected it to NASA's wide area network using the Program Support Communications Network-Internet (PSCN-I). A campus-style LAN is configured in conformance with the International Standards Organization (ISO) Open Systems Interconnect (ISO) model. Ethernet provides the physical and data link layers. Transmission Control Protocol and Internet Protocol (TCP/IP) are used for the network and transport layers. The session, presentation, and application layers employ commercial software packages. Copper-based Ethernet collision domains are constructed in each of the primary facilities and these are interconnected by routers over optical fiber links. The network and each of its collision domains are shown to meet IEEE technical configuration guidelines. The optical fiber links are analyzed for the optical power budget and bandwidth allocation and are found to provide sufficient margin for this application. Personal computers and work stations attached to the LAN communicate with and apply a wide variety of local and remote administrative software tools. The Internet connection provides wide area network (WAN) electronic access to other NASA centers and the world wide web (WWW). The WSC network reduces and simplifies the administrative workload while providing enhanced and advanced inter-communications capabilities among White Sands Complex departments and with other NASA centers

New dynamic bandwidth allocation algorithm analysis: DDSPON for ethernet passive optical networks

This project aims to present the state of the art in Dynamic Bandwidth Allocation (DBA) solutions, as well as the study and evaluation of one proposal of DBA algorithm: the Distributed Dynamic Scheduling for EPON (DDSPON), which is the UPC contribution to the research in scheduling algorithms for EPON

Design And Analysis Of a Multi-channel Optical Fibre Lan Based On Modified Csma/cd Protocol

Nowadays, optical communication is widely employed by telecommunication providers in the whole world due to its ability to support high bit rate applications. The urge to provide end-to-end fibre connectivity arises to overcome the bottleneck problem that occurs when packets are transmitted on the slower speed medium such as copper. In optical transmission, bandwidth utilisation can be improved further by using multiple wavelengths or channels in a single fibre. This thesis discusses the implementation of multiple wavelengths technique for Local Area Network (LAN) environment. It proposes a new Ethernet-based protocol that uses multiple wavelengths for transmission, which runs on a single fibre. Ethernet/IEEE 802.3 is chosen because of its widespread employment in today's network and the ability of extending the transmission rate up to gigabit transmission. Even though light does not collide with each other, receiver contention might occur if more than one signal arrives at the receiver at the same time. Therefore, some arbitration mechanism is needed to synchronise the transmission and the tuning time of the respective transmitter and receiver. The proposed design is based on the physical bus topology with n number of connected nodes and m number of operating wavelengths. All nodes are able to listen to all wavelengths. A fast control unit is used, which is responsible for packet scheduling. The packets are scheduled based on a pre-computed time. Both transmitter and receiver will be asked to tune to the· allocated wavelength. The transmitter can start transmitting and the receiver will start tuning at a specified time. Control packets are used for handshaking purposes. The main operation is placed at the control unit so that no added complexity is experienced by the receiver. Thus, this technique further reduces the cost. A suitable range of channels is obtained from the result. The network performance is evaluated against several design parameters by comparing the performance of each channel. The result shows a significant improvement whereby the throughput and efficiency are increased and average delay is minimised compared to the conventional system

New trends on Optical Access Networks: DBAs for 10G EPON and Long-Reach PON

The access network infrastructure plays an important role in the overall performance of the network, next generation access networks (NGA) must be able to access diverse services, and should incorporate adequate architectures that include mechanisms for the integration of different technologies. New optical access technologies trends are: WDM, 10 Gb/s, and longer reach/higher splits. It is also important to take into account the evolution of the installed legacy PONs to the next generation optical access networks. The present paper goes through such topics, focusing on the research being carried out to develop dynamic bandwidth algorithms for the 10 Gb/s new EPON standard (IEEE 802.3av). We summarize results and point out issues that will require further investigation.Postprint (published version

An Open Avionics and Software Architecture to Support Future NASA Exploration Missions

The presentation describes an avionics and software architecture that has been developed through NASAs Advanced Exploration Systems (AES) division. The architecture is open-source, highly reliable with fault tolerance, and utilizes standard capabilities and interfaces, which are scalable and customizable to support future exploration missions. Specific focus areas of discussion will include command and data handling, software, human interfaces, communication and wireless systems, and systems engineering and integration