Communications systems are increasingly demanding, in terms of throughput, latency, and security requirements. To combat this, a complex system of radio access networks, each with unique and dynamic performance characteristics has evolved to support modern communications. These advancements, however, bring new and interesting challenges when tuning the network to meet the specific requirements for each supported application data flow. Here, we propose two new developments to meet this challenge. First, analytical models that can accurately estimate network performance for a wide range of radio access technologies such as 5G Terrestrial and Non-Terrestrial Networking (NTN) communications must be integrated into a single cohesive simulation environment. Second, these same models will be promoted from the simulation environment to the real world, and integrated into an advanced Software Defined Networking (SDN) controller to enable predictive network planning based on the current and estimated future state of the network. To date, the set of analytical models required to support defense network analysis has not been brought together into a single network simulation tool set, nor integrated into an SDN controller suitable for 5G terrestrial and NTN scenarios.

Artificial intelligence (AI) and machine learning (ML) have been growing at an incredible rate in recent years and they show no sign of stopping. Manufacturing, educational systems, transportation architecture, and genetic research are industries where artificial intelligence algorithms have been developed and found practical applications in which they can increase task efficiency and reduce cost through process optimization, pattern recognition, and automation. At NASA, one of the goals of the cognitive communications project has been to find applications for such algorithms to next-generation communication systems. The goal of this effort is to identify areas and approaches to intelligent system design and implementation which could allow NASA to support a larger space-and ground-based network while simultaneously reducing the operational costs involved with maintaining such a system This paper will evaluate the state of various approaches by searching for algorithms which are feasible to deploy directly onto future space systems with improved processing requirements. We begin by describing a set of heuristics through which algorithms may be compared, emphasizing memory and computational requirements, and heuristic bounds. We then evaluate general-purpose processing platforms onto which such algorithms may be deployed. We also evaluate how such systems may be packaged so as to offer a deterministic set of performance and decision metrics, to make the devices easier for system designers to include in present and future systems. We conclude the paper with a discussion of our findings, as well as where and how this study might continue in the future.

The purpose of this paper is to address the extent in which 4G LTE can be used for air traffic management of small Unmanned Air Vehicles (sUAVs) 1 and the limitations and enhancements that may be necessary. We provide a brief overview of the communications aspects of the Unmanned Aerial System (UAS) 2 Traffic Management Project followed by the evolving trends in air traffic management including beyond visual line of sight (BVLOS) operations concepts and current BVLOS operational systems. Issues and Concerns are addressed including the rapidly evolving global regulations and the resulting communications requirements as well LTE downlink and uplink interference at altitude and how that interference affects command and control reliability as well as application data capabilities and mobility performance.

The use of remotely piloted unmanned aircraft systems/vehicles (UAS/UAV or drones) increases dramatically in recent years. This paper discusses the use of multiple-input and multiple-output (MIMO) technologies in cellular (i.e., LTE) based small UAS (sUAS) communications. More specifically, we will first provide background information about this work, followed by a review of state-of-the-art. Then, we will discuss the benefits of MIMO technologies and propose practical MIMO configurations (e.g., the type, size and number of antennas) that are suitable for NASA’s sUAS research and operations. Finally, the design tradeoff among multiplexing, diversity, and interference/jamming cancellation will also be discussed.

In this paper, we propose a distributed cross-layer scheduling algorithm for wireless networks with single-hop transmissions that can guarantee finite buffer sizes and meet minimum utility requirements. The algorithm can achieve a utility arbitrarily close to the optimal value with a tradeoff in the buffer sizes. The finite buffer property is not only important from an implementation perspective, but, along with the algorithm, also yields superior delay performance. In addition, another extended algorithm is provided to help construct the upper bounds of per-flow average packet delays. A novel structure of Lyapunov function is employed to prove the utility optimality of the algorithm with the introduction of novel virtual queue structures. Unlike traditional back-pressure-based optimal algorithms, our proposed algorithm does not need centralized computation and achieves fully local implementation without global message passing. Compared to other recent throughput/utility-optimal CSMA distributed algorithms, we illustrate through rigorous numerical and implementation results that our proposed algorithm achieves far better delay performance for comparable throughput/utility levels.

As the data rate requirements for space communications increases, signicant stressis placed not only on the wireless satellite communication links, but also on the groundnetworks which forward data from end-users to remote ground stations. These wide areanetwork (WAN) connections add delay and jitter to the end-to-end satellite communicationlink, eects which can have signicant impacts on the wireless communication link. It isimperative that any ground communication protocol can react to these eects such that theground network does not become a bottleneck in the communication path to the satellite.In this paper, we present our SCENIC Emulation Lab testbed which was developed to testthe CCSDS SLE protocol implementations proposed for use on future NASA communica-tion networks. Our results show that in the presence of realistic levels of network delay,high-throughput SLE communication links can experience signicant data rate throttling.Based on our observations, we present some insight into why this data throttling happens,and trace the probable issue back to non-optimal blocking communication which is sup-ported by the CCSDS SLE API recommended practices. These issues were presented aswell to the SLE implementation developers which, based on our reports, developed a newrelease for SLE which we show xes the SLE blocking issue and greatly improves the pro-tocol throughput. In this paper, we also discuss future developments for our end-to-endemulation lab and how these improvements can be used to develop and test future spacecommunication technologies.

This paper presents a real-time simulation platform for smart grid applications. The developed platform is capable of simulating complex smart grid models with large numbers of high-speed switching devices at real time. Furthermore, an integrated approach is adopted to combine real-time simulations of communication systems and electric power systems together, which provides an effective approach to examine communication and distributed control related issues in smart grids. With the flexibility in representing a wide range of communication network configurations, the developed platform can also be used to evaluate reconfiguration strategies of communication networks in smart grids. A case study is demonstrated based on this platform. Simulation results validate the capability of the platform and also show the importance of the proposed comprehensive approach for the study of smart grids.

Prior to operational use, communications hardware and software must be thoroughly tested and verified. In space-link communications, field testing equipment can be prohibitively expensive and cannot test to non-ideal situations. In this paper, we show how software and hardware emulation tools can be used to accurately model the characteristics of a satellite communication channel in a lab environment. We describe some of the challenges associated with developing an emulation lab and present results to demonstrate the channel modeling. We then show how network emulation software can be used to extend a hardware emulation model without requiring additional network and channel simulation hardware.

Directional antennas offer many potential advantages for wireless networks such as increased network capacity, extended transmission range and reduced energy consumption. Exploiting these advantages requires new protocols and mechanisms at various communication layers to intelligently control the directional antenna system. With directional antennas, many trivial mechanisms, such as neighbor discovery, become challenging since communicating parties must agree on where and when to point their directional beams to communicate. In this paper, we propose a fully directional neighbor discovery protocol called Sectored-Antenna Neighbor Discovery (SAND) protocol. SAND is designed for sectored-antennas, a low-cost and simple realization of directional antennas, that utilize multiple limited beamwidth antennas. Unlike many proposed directional neighbor discovery protocols, SAND depends neither on omnidirectional antennas nor on time synchronization. SAND performs neighbor discovery in a serialized fashion allowing individual nodes to discover all potential neighbors within a predetermined time. SAND guarantees the discovery of the best sector combination at both ends of a link, resulting in more robust and higher quality links between nodes. Finally, SAND reliably gathers the neighborhood information in a centralized location, if needed, to be used by centralized networking protocols. The effectiveness of SAND has been assessed via simulation studies and real hardware implementation.

In this paper, we propose a distributed cross-layer scheduling algorithm for networks with single-hop transmissions that can guarantee finite buffer sizes and meet minimum utility requirements. The algorithm can achieve a utility arbitrarily close to the optimal value with a tradeoff in the buffer sizes. The finite buffer property is not only important from an implementation perspective, but, along with the algorithm, also yields superior delay performance. A novel structure of Lyapunov function is employed to prove the utility optimality of the algorithm with the introduction of novel virtual queue structures. Unlike traditional back-pressure-based optimal algorithms, our proposed algorithm does not need centralized computation and achieves fully local implementation without global message passing. Compared to other recent throughput/utility-optimal CSMA distributed algorithms, we illustrate through rigorous numerical and implementation results that our proposed algorithm achieves far better delay performance for comparable throughput/utility levels.

This paper introduces the latest real time simulation technologies and their applications to the smart grid related studies. A real time simulation platform now built at the Ohio State University is described in detail. With the help of this platform, distributed real time simulation of complex power system integrated with high switching speed power electronics components, renewable energy resources, and communication networks can be fulfilled. Two case studies are performed to illustrate the platform. The first realizes intentional islanding and seamless transition of the smart grid during a power grid failure; the other integrates communication network and power network simulation together to explore communication and distributed control issues in the smart grid.

This paper introduces a platform for real time simulation and its contribution towards smart grid related research, with focus on Plug-in Hybrid Electric Vehicles (PHEV) charging stations. The current system is able to simulate in real time key elements of a smart grid such as: high speed power electronics, distributed energy resources (DER), and communication networks. A description of the platform for real time simulation is presented along with the integration of communication emulation; achieved through OPNET's System in the Loop (SITL) package. In addition, an introduction to Networked Control Systems (NCS) is presented and a case study of PHEV charging stations which displays the latest results accomplished with the current setup.

Dynamic spectrum access (DSA) is proposed to deal with the growing shortage of available leased spectrum for wireless communication. We investigate a subset of DSA referred to as dynamic spectrum leasing (DSL). At its core, DSL allows spectrum lease holders and cognitive radios to cooperate in an effort to leverage spatial diversity to improve channel utilization for both parties. In this research, cognitive radios offer their services as an intermediate relay node in an effort to improve throughput of primary users utilizing a 802.11-based channel access mechanism. In return, the cognitive radio ‘piggy-backs’ some of its own data while acting as a relay. In this paper, a simple coordination scheme is introduced that allows a network of Secondary Users to coordinate with a primary user network’s access point. This scheme does not require any modification to the primary users’ 802.11-based protocol stack as our protocol is implemented only at the access point and the Secondary Users. Analytical insights into the overhead required for this coordination and the optimization of the overhead are presented. It is shown that, given sufficient relay channel conditions, forwarding packets through a secondary relay channel can be beneficial to both parties in terms of saturation throughput.

Cognitive radio systems allow secondary users to operate on underutilized licensed spectrum. When considering highly congested communication channels, however, opportunities for channel access based on time or frequency division can be limited for secondary user networks. In this research, we consider leveraging enhanced spatial diversity through directional steerable antennas to allow secondary user channel access in parallel with licensed spectrum users. Furthermore, we consider effects of mobility on directional secondary user networks and introduce a mechanism for maintaining point-to-point directional communication links in the presence of mobility. We study the trade-offs between spatial diversity and coordination overhead to motivate the use of directional antennas, even in highly mobile cognitive radio networks.

The modernization of the current power grid has brought forward many requirements in order to make possible the vision of a smarter grid. This paper presents these challenges and the current achievements in order to aid in its transformation. It identifies developing applications within the power network; from centralized generation to distribution in terms of power electronics, power systems, and communications. A summary of the current undergoing studies in a lab setting geared towards solving the needs of the smart grid is described. Furthermore, a case study which emphasizes the communication, control, and simulation aspects for the smart grid is expressed and results are displayed in detail.