Unmanned aerial vehicles (UAVs) hold significant potential for sensing services in a large scope of area, thanks to their wide coverage and adaptable deployment. Considering the complex environment dynamics and limited sensing range, navigating multiple UAVs in a distributed way becomes challenging to implement cooperative data sensing and transmission tasks. In this paper, we optimize the trajectory design of UAVs by jointly considering the collected data volume, geographical fairness and limited energy reserve during their service period. To achieve the long-term serving objective, a memory augmented multi-agent deep reinforcement learning approach is presented to ensure energy-efficient distributed trajectory design with partial observations. Specifically, the intrinsic criterion is developed to enhance UAV spatial exploration when reaching the boundary of explored regions. Then, to address the information loss caused by incomplete observations, the spatial-temporal memory augmented actor-critic architecture is designed to extract historical contextual features for multi-UAV cooperative navigation. Furthermore, the prioritized experience replay mechanism is incorporated to enhance important experience exploitation for UAV collaboration. Extensive simulations using two real-world datasets in Shenzhen and Beijing demonstrate that the proposed method outperforms the state-of-the-art methods in terms of data collection ratio, geographical fairness, and energy consumption ratio.

For intelligent driving systems, predicting the lane change intentions of surrounding vehicles in advance is essential to improve safety and efficiency in dynamic traffic conditions. In this paper, a lane-changing intention identification method with driving style recognition is proposed to identify lane-changing intentions for intelligent vehicles, incorporating driving style recognition to enhance prediction accuracy. Firstly, a dynamic clustering framework integrating the Gaussian Mixture Model is introduced to identify the driving style of vehicles under different traffic conditions. Subsequently, a lane-changing intention recognition model based on bidirectional long short-term memory networks is proposed. By leveraging driving style enhancements, the model is refined to better simulate and comprehend driving behaviors on the road. Finally, the NGSIM dataset is used to train and evaluate the proposed prediction identification method. The results show that the accuracy is improved by 2.1% compared to state-of-the-art methods.

In 5G and beyond, discontinuous reception (DRX) is a promising energy-saving technology for massive machine-type communications (mMTC) devices with intermittent connections. However, existing DRX solutions face challenges in effectively accommodating mMTC services with critical delay requirements, particularly in a dynamic wireless environment. To address this problem, this paper proposes an intelligent DRX scheme for critical mMTC. Firstly, we modify the conventional discontinuous reception model by introducing the critical delay flag. Then we optimize the DRX by Markov Decision Process and designe the energy-delay factor to achieve the simultaneous optimization. Finally, we extract the environmental features by convolutional neural network and solve the problem by deep Q-network. A communication simulation platform is established to verify the effectiveness of the proposed method. The simulation results show that the proposed method can effectively improve the energy efficiency in mMTC situations compared with state-of-the-art.

In truck platoons with a bidirectional-leader topology, variations in channel conditions result in unreliability and high latency in vehicle-to-vehicle (V2V) communications. This paper proposes an adaptive relay selection strategy based on Q-learning (QL). The strategy ensures that all vehicles in the platoon receive safety messages from the lead vehicle quickly and reliably. Firstly, relay selection is modeled as a Markov decision process (MDP). The lead vehicle and the relays act as intelligent agents. Agents make decisions adaptively based on real-time state observations in a dynamic communication environment. Secondly, a reward function is designed based on platoon topology and channel state information statistics (CSI). The purpose is to drive the proposed strategy to learn the optimal strategy for message transmission under different environments. Lastly, the simulation results demonstrate the effectiveness and robustness of the proposed algorithm. In various channel attenuation environments, the strategy has been demonstrated to enhance the packet delivery ratio (PDR) for the platoon tail and significantly increase the platoon’s throughput.

In the future 6G intelligent transportation system, the edge server will bring great convenience to the timely computing service for connected vehicles. To guarantee the quality of service, the time-critical services need to be migrated according to the future location of the vehicle. However, predicting vehicle mobility is challenging due to the time-varying of road traffic and the complex mobility patterns of vehicles. To address this issue, a spatial-temporal awareness proactive service migration strategy is proposed in this paper. First, a spatial-temporal neural network is designed to obtain accurate mobility by using gated recurrent units and graph convolutional layers extracting features from spatial road traffic and multi-time scales driving data. Then a proactive migration method is proposed to guarantee the reliability of services and reduce energy consumption. Considering the reliability of services and the real-time workload of servers, the migration problem is modeled as a multi-objective optimization problem, and the Lyapunov optimization method is utilized to obtain utility-optimal migration decisions. Extensive simulations based on real-world datasets are performed to validate the performance of the proposed method. The results show that the proposed method achieved 6% higher prediction accuracy, 10% lower dropping rate, and 10% lower energy consumption compared to state-of-the-art methods.

High-reliability and low-latency communication is essential for timely information exchange in vehicle platooning. As a key enabler of this, the cellular vehicular-to-everything (C-V2X) network uses a sensing-based semi-persistent scheduling (SPS) protocol, where radio resources are reserved for a number of transmissions with reduced resource re-allocation and control overhead. However, consecutive access collisions may be caused by reservation conflict, which leads to long delay and threatens platoon’s stability and safety. In this paper, a coordinating resource reservation (CRR) protocol is proposed for vehicle platooning. By implementing error detection with coordination among platoon vehicles, the resource reservation is improved for reduced collisions and delay. Specifically, packet reception/loss information is sent out by platoon vehicles through their own packets. Such information is shared with transmitters and guides them to reserve new resources when access collision occurs. As a result, long delay is avoided while no extra feedback packet is introduced. Furthermore, Markov analysis is presented to evaluate the performance of SPS and the proposed CRR for vehicle platooning, providing the quantified performance gains. Finally, simulation results demonstrate the superiority of the proposed CRR in reducing packet loss and latency, compared with the legacy SPS and other state-of-the-art solutions.

In this article, we present a drone-relayed vehicular networking architecture, which aims to improve the achievable data rate of cell-edge vehicles in rural highway scenarios. Specifically, we first incorporate the decode-and-forward (DF) relay protocol with the nonorthogonal multiple access (NOMA) and maximum ratio combining (MRC) techniques, based on which an NOMA- and MRC-Enabled framework is proposed. Next, to fully exploit the advantages of the proposed framework, we separately formulate the total achievable data rate maximization and energy consumption minimization problems by jointly considering the height and 2-D trajectory optimization of relaying drone. The formulated energy consumption minimization problem is transformed into a trajectory optimization problem with obstacle avoidance constraints. Then, for the total achievable data rate maximization problem, we utilize the golden section method to design a height optimization scheme with polynomial complexity. Afterward, we improve the particle swarm optimization (PSO) algorithm, and present an effective 2-D optimization scheme. In addition, the performance superiority of the proposed NOMA- and MRC-Enabled framework is analyzed theoretically. Finally, simulation results verify the efficacy of the proposed height and trajectory optimization schemes. For instance, by using the NOMA and MRC techniques, the total achievable data rate can be improved by 24.4%. Moreover, within the same running time, a shorter trajectory can be obtained by adopting our presented trajectory optimization scheme in comparison with the current works.

Medical-care sensor networks promote the rapid development of telemedicine applications. However, in poverty-struck, disaster-struck or remote areas with limited infrastructures, it is difficult to provide fast and timely medical-care services. To address this challenge, we propose an aerial base station (ABS)-assisted medical-care sensor network, based on which the data transmission problem is investigated by jointly considering the anti-interference and anti-collision requirements. Specifically, in order to reduce the bit error rate caused by electromagnetic interferences, we first design an anti-interference method based on M-ary spread spectrum and multi-carrier modulation. Then, by introducing a multi-frequency sensor identification mechanism, an anti-collision method based on time division multiple access and frequency division multiple access is presented. Finally, simulation results demonstrate that our proposed scheme has significant advantages in anti-collision and anti-interference compared with current schemes. In quad-interference scenarios, the anti-interference performance is improved by 5.3 dB. Moreover, the anti-collision performance is also increased by 17.2%. Furthermore, in scenarios with a large number of sensors, the successful sensor identification percentage is always greater than 50%.

With the development of renewable energy, much attention has been paid to improving energy efficiency. This paper proposes a residential microgrid scheduling method to improve the energy utilization rate of residential buildings. Firstly, the power cost model for residential users and the specific charge-discharge models of electric vehicles and energy storage equipment is constructed. Then the whole energy scheduling process is formulated as a multi-variable mixed integer linear programming (MV-MILP) problem, whose objective is to minimize the power cost of end-users. The differential evolution algorithm is adopted to solve the problem, and the scaling factor adaptation is further used to accelerate the convergence. Simulation results demonstrate the effectiveness of the proposed scheduling method.

Vehicle platooning utilizes automated driving and communication to let a group of vehicles travel closely, which improves road safety, traffic efficiency and fuel economy. In a platoon system, a critical task is to guarantee reliable communication among vehicles with efficient medium access control (MAC). This paper focuses on the feasibility of the distributed resource reservation MAC for communications among platoon vehicles using the cellular vehicle-to-everything (C-V2X) technology. For this purpose, a Markov chain-based model is proposed, which precisely estimates the network performance with different information flow topologies and system configurations. The state transition matrix is deduced and the stable state distribution is obtained. Given the information flow topology, we derive the probability that a platoon vehicle successfully delivers packets to all of the designated receivers. Finally, simulation results validate the analysis. To better implement the MAC protocol in practice, we also discuss the success probability for various information flow topologies in platoon communication.

For autonomous vehicles and smart transportation services, information exchange and fusion with low latency and high reliability is critical. The 3rd Generation Partnership Project has released the cellular vehicle-to-everything (C-V2X) Mode 4 to enable direct vehicle-to-vehicle communications regardless of the cellular coverage. Mode 4 uses the sensing-based semi-persistent resource scheduling (SPS) to support autonomous resource selection by vehicles. However, channel access collisions lead to packet losses, especially in crowded scenarios. Thus, an accurate analytical model is essential to quantify the system performance, reveal how to mitigate collision and ensure system reliability and scalability. This paper focuses on the analytical modeling of the SPS and derives the access collision ratio considering both the sensed and hidden terminals in V2X. Extended simulations are conducted to verify the correctness of the analytical framework. In addition, we investigate the impact of system parameters on performance, which provides important guidelines for improving the system configuration.

The vehicular service support with adaptability, real-time, and low delay is crucial for connected vehicles. However, due to limited coverage of mobile edge computing servers and data processing capability of connected vehicles, vehicular services need to be offloaded to the edge server and adaptively migrate as the connected vehicle moves. Aiming at the adaptive migration service, a deep Q-learning service migration decision algorithm is proposed in this paper. The proposed algorithm can dynamically adjust the vehicular service migration decision according to traffic information. Furthermore, a service migration framework consisting of neural networks is proposed in this paper to improve the adaptability and real-time performance of the algorithm. By using this framework, training and decision-making can be carried out simultaneously in different places. Finally, compared with the two existing algorithms, extensive simulations are conducted to verify the effectiveness of the proposed algorithm.