Joint Optimization of Relay Selection and Transmission Scheduling for UAV-Aided mmWave Vehicular Networks

Abstract

To deal with the explosive growth of mobile traffic, millimeter-wave (mmWave) communications with abundant bandwidth resources have been applied to vehicular networks. As mmWave signal is sensitive to blockage, we introduce the unmanned aerial vehicle (UAV)-aided two-way relaying system for vehicular connection enhancement and coverage expansion. How to improve transmission efficiency and to reduce latency time in such a dynamic scenario is a challenging problem. In this paper, we formulate the joint optimization problem of relay selection and transmission scheduling, aiming to reduce transmission time while meeting the throughput requirements. To solve this problem, two schemes are proposed. The first one is the random relay selection with concurrent scheduling (RCS), a lowcomplexity algorithm implemented in two steps. The second one is the joint relay selection with dynamic scheduling (JRDS), which fully avoids relay contentions and exploits potential concurrent ability, to obtain further performance enhancement over RCS. Through extensive simulations under different environments with various flow numbers and vehicle speeds, we demonstrate that both RCS and JRDS schemes outperform the existing schemes significantly in terms of transmission time and network throughput. We also analyze the impact of threshold selection on achievable performance.

Distributed Subcarrier Assignment and Discrete Power Allocation for Multi-UAV Millimeter-Wave Cooperative OFDMA Networks With Heterogeneous QoS Consideration

“…In our study, we incorporate both line-of-sight (LOS) and nonline-of-sight (NLOS) channel components, consistent with prevailing literature [41] [40] [39]. Our model assumes that the channel gain remains consistent throughout a given time slot.…”

“…While our current system focuses on frequency-selective Rayleigh fading, each subcarrier in OFDMA is narrow enough to be considered as undergoing flat fading [26]. For future research endeavors, exploring other fading models like Rician [40] or Nakagami [39] might offer additional insights into the channel characteristics.…”

SNR Threshold-Based Relay Association and Random Phase Rotation for Cooperative Communication

“…For the last few decades, to improve the performance of wireless communication between a source node (SN) and destination node (DN), cooperative communications that employ a relay node (RN) have been extensively studied [1]- [28]. The applications of RN have recently extended from the traditional terrestrial nodes to the non-terrestrial nodes, such as the unmanned aerial vehicles [29] and satellites [30]. Various types of relaying protocols and relays exist.…”