Downlink User Power Allocation and Joint Rate Maximization in UAV-Relayed Assisted SWIPT-NOMA System

In this paper, in order to improve the performance of 5G wireless communication system and save power consumption to achieve the optimal power distribution and maximize the total user rate in a multi-user cluster of non-orthogonal multiple access (NOMA) system downlink. a SWIPT-NOMA system assisted by dynamic unmanned aerial vehicle (UAV) relay is constructed. The UAV relay dynamic programming under two-hop communication was firstly studied, and the global optimal power allocation strategy for downlink users of SWIPT-NOMA system is found. Finally, the optimal relay selection algorithm was used to maximize the total user rate, which was verified by Monto Carlo simulation. The simulation results show that the performance of the proposed system model is better than that of the traditional FDMA system scheme in terms of outage probability, energy consumption and total user rate under different distribution scenarios for the multi-user cluster deployed with dynamic UAV relay system.

The Orbital Channel Resource Control on Non-Markov Priority Systems of Mass Service Basis. Part 2. Dispatch Method

The article develops a methodology for scheduling an orbital channel resource with operational priority assignment based on the calculation of the parameters of a non-Markov service model with a limited residence time of a request in the system, which differs from known methods in that it takes into account the priority of various network subscribers, taking into account the high dynamics of their movement and the average waiting time in the service system with priority in the allocation of the orbital channel resource of the satellite command-relay system. The analysis of the influence of service quality indicators of information data flows is carried out.It is shown that the developed method of priority scheduling makes it possible to meet the requirements for the quality of service. A complex of experimental studies was carried out, which showed the possibility of ensuring the required level of stability with the deterioration in difficult conditions of radio electronic equipment, which made it possible to formulate practical proposals for improving the complex of coordination and distribution of resources of in the satellite command relay system.

3D Placement of a New Tethered UAV to UAV Relay System for Coverage Maximization

In this paper, a new relay system that uses the UAV as a relay station between the tethered UAV and ground user (TU2U2G) is proposed. The TU2U2G system replaces the base station (BS) in the cellular system with a tethered UAV (TUAV). The TUAV is a UAV that receives power over a cable from a ground control station. It has advantages of high and variable altitude up to (100m) compared to BS. In addition, it overcomes the UAV drawback of the batteries' limited capacity. After that, a 3D placement Algorithm of the UAV as a relay station in the TU2U2G system is proposed. It is presented to maximize the coverage by jointly optimizing the transmitting power and relaying distance. The TU2U2G system shows better results than the traditional cellular system in terms of optimum UAV height, maximum coverage radius, and maximum distance between BS and UAV.

Stellar Gravitational Lens Engineering for Interstellar Communication and Artifact SETI

Several recent works have proposed a “stellar relay” transmission system in which a spacecraft at the focus of a star’s gravitational lens achieves dramatic boosts in the gain of an outgoing or incoming interstellar transmission. We examine some of the engineering requirements of a stellar relay system, evaluate the long-term sustainability of a gravitational relay, and describe the perturbations and drifts that must be actively countered to maintain a relay-star-target alignment. The major perturbations on a relay-Sun-target alignment are the inwards gravity of the Sun and the reflex motion of the Sun imparted by the planets. These ∼m s−1 yr−1 accelerations can be countered with modern propulsion systems over century-long timescales. This examination is also relevant for telescope designs aiming to use the Sun as a focusing element. We additionally examine prospects for an artifact SETI search to observe stellar relays placed around the Sun by an extraterrestrial intelligence and suggest certain nearby stars that are relatively unperturbed by planetary systems as favorable nodes for a stellar relay communications system.

The Orbital Channel Resource Control on NonMarkov Priority Systems of Mass Service Basis. Part 1.Operational Distribution Model

In work systems analysis of process of target functioning of the satellite command relay system (SCRS) in the conditions of a difficult radio-electronic situation is carried out. The carried-out analysis of perspectives of development of a subsystem of relaying of SKRS of orbital grouping of spacecrafts of remote sensing of Earth, allowed to draw a conclusion on features of a stage of coordination planning of the means of a subsystem of relaying consisting in distribution of SKRS the orbital channel resource (OCR) on the basis of the non-Markov priority systems of service. The model of operational distribution of ROC of a subsystem of relaying on the basis of the priority systems of service in which, unlike the known models, time of stay of the request in a system is limited is received, limits for a type of distribution of holding time of requests are lifted and also expression for calculation of the initial moments of distribution of waiting time of messages of different priorities is received. Use of model allows to evaluate the probability of untimely delivery of details and also to provide required figures of merit of service of priority flows and at the expense of it to provide the required connectivity and stability of SKRS in general.

Analysis of a mass-spring-relay system with periodic forcing

The dynamics of a hysteretic relay oscillator with harmonic forcing is investigated. Periodic excitation of the system results in periodic, quasi-periodic, chaotic and unbounded behavior. An explicit Poincaré map is constructed with an implicit constraint on the switching time. The stability of the fixed points of the Poincaré map corresponding to period-one solutions is investigated. By varying the forcing parameters, we observed a saddle-center and a pitchfork bifurcation of two centers and a saddle-type fixed point. The global dynamics of the system exhibits discontinuity induced bifurcations of the fixed points.