Greedy based proactive spectrum handoff scheme for cognitive radio systems

The aeronautical spectrum becomes increasingly congested due to raising number of non-stationary users, such as unmanned aerial vehicles (UAVs). With the growing demand to spectrum capacity, cognitive radio technology is a promising solution to maximize the utilization of spectrum by enabling communication of secondary users (SUs) without interfering with primary users (PUs). In this paper we formulate and solve a multi-parametric objective function for proactive handoff scheme in multiple input multiple output (MIMO) system constrained by QoS requirements. To improve the efficiency of handoff scheme for multiple communicating UAVs the greedy strategy is adopted. An innovative aspect of our solution includes consideration of quality of service (QoS) components, e.g. opportunistic service time, channel quality, etc. Some of these components, for example collision probability and false alarm probability, affect QoS in a negative way and are considered as constraints. Simulation of handoff scheme has been performed to evaluate the performance of the proposed algorithm in selecting multiple channels when the spectrum environment changes. The performance of handoff scheme is compared with random selection method and is found outperforming the random selection method in terms of averaged utilization ratio. Analysis of results has shown that the spectrum utilization ratio can be doubled by considering wider bandwidth (more channels) and by making QoS requirements less strict. In both cases this leads to near-linear increase in time consumption for handoff scheme generation

Safe, Remote-Access Swarm Robotics Research on the Robotarium

This paper describes the development of the Robotarium -- a remotely accessible, multi-robot research facility. The impetus behind the Robotarium is that multi-robot testbeds constitute an integral and essential part of the multi-agent research cycle, yet they are expensive, complex, and time-consuming to develop, operate, and maintain. These resource constraints, in turn, limit access for large groups of researchers and students, which is what the Robotarium is remedying by providing users with remote access to a state-of-the-art multi-robot test facility. This paper details the design and operation of the Robotarium as well as connects these to the particular considerations one must take when making complex hardware remotely accessible. In particular, safety must be built in already at the design phase without overly constraining which coordinated control programs the users can upload and execute, which calls for minimally invasive safety routines with provable performance guarantees.Comment: 13 pages, 7 figures, 3 code samples, 72 reference

A Methodology to Repair or Deorbit LEO Satellite Constellations

In this thesis, mitigation of space debris is addressed by examining an approach for repair or de-orbit of a specific population of non-functional Low Earth Orbit (LEO) satellites. Basic orbital mechanics propagation of the orbits was used as the process for computing a solution to the time and intercept position for the targeted satellites. Optimal orbital maneuvers to reach the target satellites from a pre-established orbit were also considered. In this way minimum ΔV budget, rendezvous time and mass budgets were managed. The Clohessy-Wiltshire Equations and two-impulsive rendezvous maneuvers were used to determine the orbital path of a chase satellite between two position vectors, along with the time of flight. A monopropellant propulsion system was assumed in order to estimate propellant mass requirements. This methodology can be applied to a variety of satellite constellations, as implemented using MatLab and Analytical Graphics, Inc. STK software. Several cases were investigated in the study. Simulations showed that the methodology can provide guidance for the rendezvous process, facilitating a minimum ΔV budget and minimum rendezvous time

Comprehensive survey on quality of service provisioning approaches in cognitive radio networks : part one

Much interest in Cognitive Radio Networks (CRNs) has been raised recently by enabling unlicensed (secondary) users to utilize the unused portions of the licensed spectrum. CRN utilization of residual spectrum bands of Primary (licensed) Networks (PNs) must avoid harmful interference to the users of PNs and other overlapping CRNs. The coexisting of CRNs depends on four components: Spectrum Sensing, Spectrum Decision, Spectrum Sharing, and Spectrum Mobility. Various approaches have been proposed to improve Quality of Service (QoS) provisioning in CRNs within fluctuating spectrum availability. However, CRN implementation poses many technical challenges due to a sporadic usage of licensed spectrum bands, which will be increased after deploying CRNs. Unlike traditional surveys of CRNs, this paper addresses QoS provisioning approaches of CRN components and provides an up-to-date comprehensive survey of the recent improvement in these approaches. Major features of the open research challenges of each approach are investigated. Due to the extensive nature of the topic, this paper is the first part of the survey which investigates QoS approaches on spectrum sensing and decision components respectively. The remaining approaches of spectrum sharing and mobility components will be investigated in the next part

The AFIT ENgineer, Volume 2, Issue 4

In this issue: AFMC Spark Tank Semi-finalist New AFIT Patents 2020 Graduate School Award Winners Airmen and Artificial Intelligence Nuclear Treaty Monitorin

The AFIT ENgineer, Volume 2, Issue 4

In this issue: AFMC Spark Tank Semi-finalist New AFIT Patents 2020 Graduate School Award Winners Airmen and Artificial Intelligence Nuclear Treaty Monitorin

Leadership, innovation and strategy development in military hard structures: Bringing chaos to order

This thesis is a critical engagement with the development of leadership for officers in the United States Air Force (USAF) at the USAF’s Air University (AU) through specially designed graduate level education courses in leadership and innovation. These programs have been in regular demand and requests for their dissemination to various other parts of the military are frequent. They are also the seed bed for a number of change initiatives and graduates are to be found at the highest level of decision making. This responsibility to anticipate the future and contribute to supporting officers to lead in increasing complexity, requires me to be constantly questioning myself, my own leadership, my ideas and the ideas of others to inform the design and ongoing evolution of these programs. This evolution is nudged not only from questioning but from the input of students, faculty, and staff in a collaborative endeavor. The context is leadership in, what I refer to as, a ‘hard structure’, one that is heavily regulated and bureaucratized with non-negotiable expectations of its members in service to the protection of systems of security, from economy and law enforcement to trade and civil liberties. In the context of this particular hard structure of the military, the mandate to safeguard a nation’s institutions and alliances can also be a mandate to kill on small and large scales, if ordered to, in the interests of national and international security. This critique has brought into greater awareness the ambiguities, contradictions, and paradoxes faced by military leadership; it questions whether existing formulaic models are relevant to practice in field conditions and tracks my search for concepts as translational devices to negotiate opposing tensions and to see the possibilities in ‘the middle way’. I collaborate with students, peers, and literature to enable leadership and innovation education to shift from a monoperspective to a multi-perspective lens and from leadership as some form of mono-discipline to a multidisciplinary one. I explore the relevance of approaches and concepts including transdisciplinary perspectives as complementary ways to approach leadership for the future. While innovation is part of the leadership portfolio, I arrive at the need to introduce strategy into that portfolio and have set in motion an initiative to integrate all three into a Master’s program that stretches not only the skills of young officers but their imagination. I can now articulate more clearly the concepts, ideas and distilled experience that informs the content and the delivery of the leadership and innovation programs– a transparency of my own understanding including (i) context is pivotal (ii) once leaders understand and are comfortable with their ‘being’ they will be confident to seek cognitive diversity to complement any perceived or actual ‘weaknesses’ in themselves (iii) this in turn results in strong, cohesive teams where individuals can feel less inhibited in expressing and comprehending their strengths and can strive to help each other flourish with an understanding that leaders can only be as great as the teams they create