Results for “communication protocols” — Page 65

NASA NTRS2002

Performance, Capacity and Limitations of AMSS Communications

This paper reports on the performance of Aeronautical Mobile Satellite Service (AMSS), based on simulation results, when incorporated into the Aeronautical Telecommunications Network (ATN). A comparison between its performance under current data traffic load and under future ATN traffic load was used to determine the reliability of AMSS in providing continuous communications between the ground and the aircraft over remote regions of the globe. The simulation involved modeling AMSS through the use of the published standards to ensure the accuracy of the results. Although the results indicated that there is indeed a reduced capacity (to about one-fourth) and efficiency of the system at the increased traffic load, the reduction in performance does not lead to the conclusion that an alternative to AMSS must be found. On the contrary, some modifications to the protocols controlling the operation of AMSS and updating the system with new technologies, would make it as valid a solution to the problem as it is today.

Ripamonti, Claudio↗

NASA NTRS2006

CFDP Performance over Weather-Dependent Ka-Band Channel

This study presents an analysis of the delay performance of the CCSDS File Delivery Protocol (CFDP) over weather-dependent Ka-band channel. The Ka-band channel condition is determined by the strength of the atmospheric noise temperature, which is weather dependent. Noise temperature data collected from the Deep Space Network (DSN) Madrid site is used to characterize the correlations between good and bad channel states in a two-state Markov model. Specifically, the probability distribution of file delivery latency using the CFDP deferred Negative Acknowledgement (NAK) mode is derived and quantified. Deep space communication scenarios with different file sizes and bit error rates (BERs) are studied and compared. Furthermore, we also examine the sensitivity of our analysis with respect to different data sampling methods. Our analysis shows that while the weather-dependent channel only results in fairly small increases in the average number of CFDP retransmissions required, the maximum number of transmissions required to complete 99 percentile, on the other hand, is significantly larger for the weather-dependent channel due to the significant correlation of poor weather states.

weather↗

NASA NTRS2006

CFDP Performance over Weather-dependent Ka-band Channel

This study presents an analysis of the delay performance of the CCSDS File Delivery Protocol (CFDP) over weather-dependent Ka-band channel. The Ka-band channel condition is determined by the strength of the atmospheric noise temperature, which is weather dependent. Noise temperature data collected from the Deep Space Network (DSN) Madrid site is used to characterize the correlations between good and bad channel states in a two-state Markov model. Specifically, the probability distribution of file delivery latency using the CFDP deferred Negative Acknowledgement (NAK) mode is derived and quantified. Deep space communication scenarios with different file sizes and bit error rates (BERs) are studied and compared. Furthermore, we also examine the sensitivity of our analysis with respect to different data sampling methods. Our analysis shows that while the weather-dependent channel only results in fairly small increases in the average number of CFDP retransmissions required, the maximum number of transmissions required to complete 99 percentile, on the other hand, is significantly larger for the weather-dependent channel due to the significant correlation of poor weather states.

deep space communications↗

NASA NTRS2023

Exploration Extra-Vehicular Mobility Unit (xEMU) Composite Hard Upper Torso (CHUT) Development

The xEMU is the Exploration Mobility Unity or space suit designed for microgravity (cislunar and low earth orbit (LEO)) and lunar surface operations. This suit design allows crewmembers to perform extravehicular exploration, science, construction, maintenance, and contingency operations while unattached to a vehicle for life support in pressure and thermal environments that exceed human capability. The xEMU provides life support, environmental protection, and communications capabilities to the EVA crewmember while allowing sufficient mobility and visibility to perform dexterous EVA tasks. The effort documented in this paper, addressed the design, analysis, manufacturing, full-scale test article testing and validation for a Composite Hard Upper Torso(CHUT)unit. Design and analysis of the CHUT was based on measured B-basis properties of the selected S-glass/epoxy composite, and established final geometry, composite layup and interface details that met requirements. A complete manufacturing and assembly protocol was established for the CHUT starting from composite layup in the tool, to final assembly of all interface metal hardware prior to delivery to NASA for suit integration. Full-scale CHUT test articles underwent static and fatigue pressure testing (2 lifetimes), impact testing at critical stress locations for tool drop/microgravity scenarios, followed by post-impact fatigue testing. Effect of manufacturing defects was evaluated by manufacturing a full-scale CHUT with 0.375”/0.5” defects at critical stress locations, followed by static and life-cycle fatigue testing. In all cases, the CHUT design met or exceeded mass, structural, interface and functional requirements. Two (2) complete CHUT articles were delivered to NASA for full-scale suit integration and testing.

spacesuit↗

NASA NTRS2023

Composite Hard Upper Torso (CHUT) for xEMU Space Suit

The xEMU is the Exploration Mobility Unity or space suit designed for microgravity (cislunar and low earth orbit (LEO)) and lunar surface operations. This suit design allows crewmembers to perform extravehicular exploration, science, construction, maintenance, and contingency operations while unattached to a vehicle for life support in pressure and thermal environments that exceed human capability. The xEMU provides life support, environmental protection, and communications capabilities to the EVA crewmember while allowing sufficient mobility and visibility to perform dexterous EVA tasks. The effort documented in this paper, addressed the design, analysis, manufacturing, full-scale test article testing and validation for a Composite Hard Upper Torso(CHUT)unit. Design and analysis of the CHUT was based on measured B-basis properties of the selected S-glass/epoxy composite, and established final geometry, composite layup and interface details that met requirements. A complete manufacturing and assembly protocol was established for the CHUT starting from composite layup in the tool, to final assembly of all interface metal hardware prior to delivery to NASA for suit integration. Full-scale CHUT test articles underwent static and fatigue pressure testing (2 lifetimes), impact testing at critical stress locations for tool drop/microgravity scenarios, followed by post-impact fatigue testing. Effect of manufacturing defects was evaluated by manufacturing a full-scale CHUT with 0.375”/0.5” defects at critical stress locations, followed by static and life-cycle fatigue testing. In all cases, the CHUT design met or exceeded mass, structural, interface and functional requirements. Two (2) complete CHUT articles were delivered to NASA for full-scale suit integration and testing.

spacesuit↗

NASA NTRS2009

Synchronized Position Hold, Engage, Reorient, Experimental Satellites

Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) are bowling-ball sized spherical satellites. They will be used inside the space station to test a set of well-defined instructions for spacecraft performing autonomous rendezvous and docking maneuvers. Three free-flying spheres will fly within the cabin of the station, performing flight formations. Each satellite is self-contained with power, propulsion, computers and navigation equipment. The results are important for satellite servicing, vehicle assembly and formation flying spacecraft configurations. SPHERES is a testbed for formation flying by satellites, the theories and calculations that coordinate the motion of multiple bodies maneuvering in microgravity. To achieve this inside the ISS cabin, bowling-ball-sized spheres perform various maneuvers (or protocols), with one to three spheres operating simultaneously . The Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) experiment will test relative attitude control and station-keeping between satellites, re-targeting and image plane filling maneuvers, collision avoidance and fuel balancing algorithms, and an array of geometry estimators used in various missions. SPHERES consists of three self-contained satellites, which are 18 sided polyhedrons that are 0.2 meter in diameter and weigh 3.5 kilograms. Each satellite contains an internal propulsion system, power, avionics, software, communications, and metrology subsystems. The propulsion system uses CO2, which is expelled through the thrusters. SPHERES satellites are powered by AA batteries. The metrology subsystem provides real-time position and attitude information. To simulate ground station-keeping, a laptop will be used to transmit navigational data and formation flying algorithms. Once these data are uploaded, the satellites will perform autonomously and hold the formation until a new command is given.

Miller, David W.↗

NASA NTRS2017

On the Development and Application of High Data Rate Architecture (HiDRA) in Future Space Networks

Historically, space missions have been severely constrained by their ability to downlink the data they have collected. These constraints are a result of relatively low link rates on the spacecraft as well as limitations on the time during which data can be sent. As part of a coherent strategy to address existing limitations and get more data to the ground more quickly, the Space Communications and Navigation (SCaN) program has been developing an architecture for a future solar system Internet. The High Data Rate Architecture (HiDRA) project is designed to fit into such a future SCaN network. HiDRA's goal is to describe a general packet-based networking capability which can be used to provide assets with efficient networking capabilities while simultaneously reducing the capital costs and operational costs of developing and flying future space systems.Along these lines, this paper begins by reviewing various characteristics of modern satellite design as well as relevant characteristics of emerging technologies (such as free-space optical links capable of working at 100+ Gbps). Next, the paper describes HiDRA's design, and how the system is able to both integrate and support the operation of not only today's high-rate systems, but also the high-rate systems likely to be found in the future. This section also explores both existing and future networking technologies, such as Delay Tolerant Networking (DTN) protocol (RFC4838 citeRFC:1, RFC5050citeRFC:2), and explains how HiDRA supports them. Additionally, this section explores how HiDRA is used for scheduling data movement through both proactive and reactive link management. After this, the paper moves on to explore a reference implementation of HiDRA. This implementation is currently being realized based on a Field Programmable Gate Array (FPGA) memory and interface controller that is itself controlled by a local computer running DTN software. Next, this paper explores HiDRA's natural evolution, which includes an integration path for software-defined networking (SDN) switches. This section also describes considerations for both near-Earth and deep-space instantiations of HiDRA, describing how differences in latencies between the environments will necessarily influence how the system is configured and the networks operate. Finally, this paper describes future work. This section includes a description of a potential ISS implementation which will allow rapid advancement through the technology readiness levels (TRL). This section also explores work being done to support HiDRA's successful implementation and operation in a heterogeneous network: such a network could include communications equipment spanning many vintages and capabilities, and one significant aspect of HiDRA's future development involves balancing compatibility with capability.

DTN↗

DOE OSTI2022

Advanced architectures for high-performance quantum networking

As practical quantum networks prepare to serve an ever-expanding number of nodes, there has grown a need for advanced auxiliary classical systems that support the quantum protocols and maintain compatibility with the existing fiber-optic infrastructure. We propose and demonstrate a quantum local area network design that addresses current deployment limitations in timing and security in a scalable fashion using commercial off-the-shelf components. First, we employ White Rabbit switches to synchronize three remote nodes with ultra-low timing jitter, significantly increasing the fidelities of the distributed entangled states over previous work with Global Positioning System clocks. Second, using a parallel quantum key distribution channel, we secure the classical communications needed for instrument control and data management. Therefore, the conventional network that manages our entanglement network is secured using keys generated via an underlying quantum key distribution layer, preserving the integrity of the supporting systems and the relevant data in a future-proof fashion.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2021

Named Data Networking for DER Cybersecurity

We present our research findings on the novel NDN protocol. In this work, we defined key attack scenarios for possible exploitation and detail software security testing procedures to evaluate the security of the NDN software. This work was done in the context of distributed energy resources (DER). The software security testing included an execution of unit tests and static code analyses to better understand the software rigor and the security that has been implemented. The results from the penetration testing are presented. Recommendations are discussed to provide additional defense for secure end-to-end NDN communications.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2023

(U) MIT Capstone Project (Final Report)

This capstone project focuses on modernizing the design development processes, production development processes, and communication between design agencies (DAs) and production agencies (PAs) to decrease the timeline from conceptual study to first production unit. To focus the scope, the researchers looked only at interactions between the DA, Lawrence Livermore National Lab (LLNL), and the PA, Kansas City National Security Campus (KCNSC). The project’s system problem statement (SPS) is: TO decrease the time from conceptual study to first production unit BY reducing the DA to-PA engineering interface complexity USING digital engineering software that centralizes product definition and information exchange protocols.

42 ENGINEERING↗

DOE OSTI2020

Network traffic control for multi-homed end-hosts via SDN

Software-defined networking (SDN) is an emerging technology of efficiently controlling and managing computer networks, such as in data centres, wide-area networks, as well as in ubiquitous communication. In this study, the authors explore the idea of embedding the SDN components, represented by SDN controller and virtual switch, in end-hosts to improve network performance. In particular, the authors consider load balancing across multiple network interfaces on end-hosts with different link capacity scenarios. The authors have explored and implemented different SDN-based load-balancing approaches based on OpenFlow software switches, and have demonstrated the feasibility and the potential of this approach. The proposed system has been evaluated with MultiPath transmission control protocol (MPTCP). Furthermore, the proposed results demonstrated the potential of applying the SDN concepts on multi-homed devices resulting in an increase in achieved throughput of 55% compared to the legacy single network approach and 10% compared to the MPTCP.

97 MATHEMATICS AND COMPUTING↗

NASA NTRS1987

Performance analysis of an optimal file transfer protocol for integrated mobile satellite services

A file-transfer protocol based on the selective-repeat automatic-retransmission-request (ARQ) scheme has been developed for the Mobile Satellite Experiment (MSAT-X). In this protocol, each file is divided into packets, which are error-detected and acknowledge individually. A file can be transferred in either the open- or closed-end connection. In the open-end connection, the file is transmitted continuously according to the selective-repeat scheme until all packets are positively acknowledged; in the closed-end connection, each retransmission will initiate its own connection request. The relationship between the packet size and the average end-to-end delay in the mobile fading environment is investigated. The communications channel uses trellis-coded modulation with symbol interleaving, packet replication, and error detection. The packet error performance in such a channel is evaluated by simulation, and the optimal packet size for various operating conditions is derived, using the simulated results. It is shown that for a symbol-energy-to-noise ratio of 12 dB, each file should be divided into packets of length between 256 bits and 512 bits (excluding the overhead) to minimize the average end-to-end delay.

Wang, Charles C.↗

NASA NTRS2022

Towards the Development of a Multi-Agent Cognitive Networking System for the Lunar Environment

This paper details the development of a multi-agent cognitive system intended to optimize networking performance in the lunar environment. One concept of the future of lunar communication, LunaNet, outlines a complex network of networks. Challenges such as scalability, interoperability, and reliability must first be addressed to successfully fulfill this vision. Machine intelligence can greatly reduce the reliance on human operators and enable efficient operations for tasks such as scheduling and network management. Machine learning, artificial intelligence, and other automated decision-making techniques can be used to allow network nodes to intelligently sense and adapt to changes in the environment such as link disruptions, new nodes joining the network, and support for a diverse range of protocols. Cognitive networking seeks to evolve these technologies into an autonomous system with improved science data return, reliability, and scalability. In this paper, we study four main areas as a means to further develop cognitive networking capabilities: networking protocol development, analysis of wireless data for modeling and simulation, development of algorithms for a multi-agent system, and spectrum sensing technology.

cognitive networking↗

DOE OSTI2021

Lieb-Robinson Light Cone for Power-Law Interactions

The Lieb-Robinson theorem states that information propagates with a finite velocity in quantum systems on a lattice with nearest-neighbor interactions. What are the speed limits on information propagation in quantum systems with power-law interactions, which decay as 1 / r α at distance r ? Here, we present a definitive answer to this question for all exponents α > 2 d and all spatial dimensions d . Schematically, information takes time at least r min { 1 , α - 2 d } to propagate a distance r . As recent state transfer protocols saturate this bound, our work closes a decades-long hunt for optimal Lieb-Robinson bounds on quantum information dynamics with power-law interactions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

NASA NTRS1990

MSAT network architecture

The Mobile Satellite (MSAT) communications system will support mobile voice and data services using circuit switched and packet switched facilities with interconnection to the public switched telephone network and private networks. Control of the satellite network will reside in a Network Control System (NCS) which is being designed to be extremely flexible to provide for the operation of the system initially with one multi-beam satellite, but with capability to add additional satellites which may have other beam configurations. The architecture of the NCS is described. The signalling system must be capable of supporting the protocols for the assignment of circuits for mobile public telephone and private network calls as well as identifying packet data networks. The structure of a straw-man signalling system is discussed.

Davies, N. G.↗

NASA NTRS2000

Aeronautical Related Applications Using ATN and TCP/IP Research Report

The course for the future aeronautical communications architecture has been defined for more than 10 years and is known as the Aeronautical Telecommunication Network (ATN). However, the operational implementations of making use of the ATN remain 3-5 years away, and these implementations are still only in the early phases of long-range projects. Thus, it is an objective of this effort to consider what the potential outcome within the air transport industry may be, given the rapid growth in commercial-off-the-shelf (COTS) products, networks, and services that are based upon the Internet TCP/IP protocol suite.

Dhas, C.↗

DOE OSTI2022

Centralized and Decentralized Distributed Energy Resource Access Control Implementation Considerations.

A global transition to power grids with high penetrations of renewable energy generation is being driven in part by rapid installations of distributed energy resources (DER). New DER equipment includes standardized IEEE 1547-2018 communication interfaces and proprietary communications capabilities. Interoperable DER provides new monitoring and control capabilities. The existence of multiple entities with different roles and responsibilities within the DER ecosystem makes the Access Control (AC) mechanism necessary. In this paper, we introduce and compare two novel architectures, which provide a Role-Based Access Control (RBAC) service to the DER ecosystem’s entities. Selecting an appropriate RBAC technology is important for the RBAC administrator and users who request DER access authorization. The first architecture is centralized, based on the OpenLDAP, an open source implementation of the Lightweight Directory Access Protocol (LDAP). The second approach is decentralized, based on a private Ethereum blockchain test network, where the RBAC model is stored and efficiently retrieved via the utilization of a single Smart Contract. We have implemented two end-to-end Proofs-of-Concept (PoC), respectively, to offer the RBAC service to the DER entities as web applications. Finally, an evaluation of the two approaches is presented, highlighting the key speed, cost, usability, and security features.

42 ENGINEERING↗

NASA NTRSDate not supplied

Towards the Development of a Multi-Agent Cognitive Networking System for the Lunar Environment

This paper details the development of a multi-agent cognitive system intended to optimize networking performance in the lunar environment. NASA’s current concept of the future of lunar communication, LunaNet, outlines a complex network of networks. Challenges such as scalability, interoperability and reliability must first be addressed to successfully fulfill this vision. Machine intelligence can greatly reduce the reliance on human operators and enable efficient operations for tasks such as scheduling and network management. The application of machine learning, artificial intelligence, and other automated decision-making techniques can be used to allow network nodes to intelligently sense and adapt to changes in the environment such as link disruptions, new nodes joining the network, and support for a diverse range of protocols. Cognitive networking seeks to evolve these technologies into an autonomous system with improved science data return, reliability, and scalability. In this paper, we study three main areas a means to further develop cognitive networking capabilities: networking and flight software development, analysis of wireless data for modeling and simulation, and development of algorithms for a multi-agent system.

Rachel Dudukovich↗