Performance Evaluation最新文献

In this paper, we investigate the secrecy performance of an unmanned aerial vehicle (UAV)-based full-duplex (FD) two-way relay non-orthogonal multiple access (TWR-NOMA) system with two terrestrial users and an eavesdropper. To ensure secure communications, a UAV acts as an aerial relay station, which not only forwards confidential information to legitimate users but also keeps emitting the jamming signal to degrade the performance of any potential eavesdropper. The ergodic secrecy rate (ESR) and secrecy outage probability (SOP) of users and the system are successfully investigated under the assumption of imperfect successive interference and self-interference cancellation. In addition, to provide a better understanding of the secrecy performance, mathematical expressions of asymptotic ESR, secrecy slope, asymptotic SOP, and secrecy diversity order are also studied. Simulation results demonstrate that the FD TWR-NOMA system attains better secrecy performance than that of the FD TWR-NOMA system with a terrestrial relay, the FD TWR-NOMA system without jamming signal, as well as the half-duplex TWR-NOMA system. The secrecy performance of the system is significantly enhanced when UAVs approach the remote user. Furthermore, there is a reasonable power allocation value for jamming and legitimate signals on the UAV to improve secrecy performance.

In this paper we consider two resource allocation problems of URLLC traffic and eMBB traffic in uplink 5G networks. We propose to divide frequencies into a common region and a grant-based region. Frequencies in the grant-based region can only be used by eMBB traffic, while frequencies in the common region can be used by eMBB traffic as well as URLLC traffic. In the first resource allocation problem we propose a two-player game to address the size of the grant-based region and the size of the common region. We show that this game has specific pure Nash equilibria. In the second resource allocation problem we determine the number of bits that each eMBB user can transmit in a request-grant cycle. We propose a constrained optimization problem to minimize the variance of the number of bits granted to the eMBB users. We show that a water-filling algorithm solves this constrained optimization problem. From simulation, we show that our scheme, consisting of resource allocation according to Nash equilibria of a game, persistent random transmission of URLLC packets and allocation of eMBB packets by a water-filling algorithm, works better than four other heuristic methods.

In this paper we establish a necessary and sufficient stability condition for a stochastic ring network. Such networks naturally appear in a variety of applications within communication, computer, and road traffic systems. They typically involve multiple customer types and some form of priority structure to decide which customer receives service. These two system features tend to complicate the issue of identifying a stability condition, but we demonstrate how the ring topology can be leveraged to solve the problem.

Online service providers aim to satisfy the tail performance requirements of customers through Service-Level Objectives (SLOs). One approach to ensure tail performance requirements is to model the service as a Markov chain and obtain its steady-state probability distribution. However, obtaining the distribution can be challenging, if not impossible, for certain types of Markov chains, such as those with multi-dimensional or infinite state-space and state-dependent transitions. Examples include M/M/1 with Discriminatory Processor Sharing (DPS) and preemptive M/M/c with multiple priority classes and customer abandonment.

To address this fundamental problem, we propose a Lyapunov function-based state-space truncation technique that leverages moments or bounds on moments of the state variables. This technique allows us to obtain tight truncation bounds while ensuring arbitrary probability mass guarantees for the truncated chain. We highlight the efficacy of our technique for multi-dimensional DPS and M/M/c priority queue with abandonment, demonstrating a substantial reduction in state space (up to 74%) compared to existing approaches. Additionally, we present three practical use cases that highlight the applicability of our truncation technique by analyzing the performance of the DPS system.