Understanding the characteristics of UAV-to-ground communication channels is important for the development of future intelligent wireless environments. This paper presents a broadband UAV-to-ground channel measurement campaign at 2.7 GHz, based on which the large scale and the small scale channel characteristics are evaluated for UAV flight altitudes of 300 and 400 meters in a rural environment. For these two altitudes, a Log-distance path loss model is developed and the shadow fading is found to be Log-normal distributed. For the small-scale characteristics, the amplitude of the received signal is compared with a number of different distributions and the Kolmogorov-Smirnov (KS) test is applied to determine that the Ricean distribution is the best fit among considered theoretical fading distributions. Finally, a distance dependent K factor model is proposed in the paper.

To establish a stable, effective and reliable communication systems between unmanned aerial vehicle (UAV) and mobile vehicles, the propagation characteristics of air-ground (AG) wireless channels need to be better understand. In this paper, a narrowband multi-link channel measurement for UAV to mobile vehicles at 2.4 and 5.9 GHz is presented. Based on the measured data, some essential channel characteristics such as large-scale fading (LSF) including path loss, shadow fading (SF), and small-scale fading (SSF) including fading depth (FD), magnitude distribution and Rician distribution K-factor are analyzed. Then the cross-correlation characteristics of different channel parameters and receiving antenna numbers at 2.4 GHz and 5.9 GHz are systematically investigated. These researches provide some references to optimize antenna design and multi-link channel modeling of UAV to mobile vehicle communication systems in future intelligent transportation system (ITS).

As a promising new form in mobile edge computing network, Vehicular Edge Computing (VEC) can further improve the Quality of Service (QoS) of users. However, when edge servers are damaged or overloaded, the requirements of users are difficult met by VEC servers owing to incomplete connectivity and time-varying channel conditions in dynamic and resource-limited vehicular networks. In this paper, we introduce Unmanned Aerial Vehicle (UAV) to enhance the connectivity and total resources in the vehicular networks. Added to that, we focus on the problem of computation-intensive graph jobs scheduling, where the information interactions among the traditional vehicles, autonomous vehicles and UAV are integrated. And the above scheduling problem is modeled as a binary nonlinear programming problem aiming at minimizing average completion delay of jobs. Then, we develop an effective multiple jobs scheduling scheme by considering the scheduling order of multiple jobs, the remaining processing delay of servers, and the available resources of vehicular networks, which consists of two stages: (1) the multiple jobs priority scheduling algorithm for optimizing the jobs scheduling order; (2) the task offloading decision algorithm for optimizing average completion delay of jobs. Finally, the effectiveness of proposed scheme is proved by extensive simulation experiments. Compared with the other schemes, the proposed scheme can effectively reduce average completion delay of jobs.

Air-to-ground (A2G) communication is a fundamental technology for integration of unmanned aerial vehicle (UAV) in the intelligent transportation system (ITS), where accurate analysis and modeling of UAV A2G wireless channel are of great importance for communication algorithm development. In this letter, we present a comprehensive analysis and modeling of low-altitude UAV A2G channel at 2.4 and 5.9 GHz based on multilink channel measurement campaign. The value of path loss as a function of the elevation angle and distance is proposed. Further, the shadow fading is analyzed for different frequency bands and the spatial correlation is evaluated. Particularly, it is found that the influence of UAV altitude on shadowing is significant and should be considered when developing A2G communication system.

This paper presents an implementation of a channel simulator in software-defined-radio(SDR). The implementation of simulator is implemented on an Universal Software Radio Peripheral (USRP) and GNU Radio software. Simulation part is implemented in GNU Radio software, and RF conversion is performed by USRP. This channel simulator includes multipath simulation and fading simulation, such as Rayleigh and Rician fading channels. Fading simulation is implemented by sum-of-sinusoids-based model, and using fir filter to realize fractional delay in multipath simulation. Using the proposed method, we can efficiently achieve the desired simulate result.

Physical Cell Identity (PCI), as a significant network configuration parameter, is a key factor in the process of User Equipment (UE) accessing to the cell. There are more cells than the number of PCIs, as cell density grows in the ultra dense network, unreasonable PCI configuration will cause conflicts, confusions and Mod- $k$ conflicts (CCM) between cells. However, there is still a lack of work related to the effect of the Mod- $k$ conflict during PCI configuration. In this paper, we propose a PCI configuration scheme that can reduce the occurrence of CCM among cells by using PCIs Grouping and Cells Clustering (named as PGCC). First, a CCM graph is established based on location and handover rate among cells. Second, PCIs are divided into different groups according to Mod- $k$ conflicts, and cells are clustered by the number of groups. Then, the graph coloring algorithm is used to configure the PCI based on the grouping and clustering. Finally, the effectiveness of the scheme is verified by numerous simulation experiments. Compared to other schemes, the PGCC scheme can reduce CCM between cells.

This paper deduces a variational bayesian method for complex tensors based on mean field theory in MIMO-OFDM systems, which realizes automatic determination of tensor rank and applies CP decomposition of tensors to practical measurements through the tensor space structure. In this method, the channel harmonics are firstly estimated, and then used to implement the angle positioning method. To the end, the estimated harmonic errors and positioning errors are analyzed, confirming the achievability of this method.

To achieve the economy, green, and high efficiency, the platoon of autonomous vehicles on the highway is a key service for the autonomous transportation system (ATS). At present, there have been few works related to the service components and the cooperation relationship in service architecture of platoon. Therefore, this paper first abstracts the basic services and operational processes based on the literature analysis. On this basis, the platoon service architecture is constructed and then it is divided into three generations, where the evolution of service component subset, then the cooperation relationship is analyzed. Third, the subset of the required service components and their cooperation relationship are analyzed for the typical driving obstacle encounter scenario, according to whether the roadside can facilitate the out-of-team awareness through communication. In addition, an example is used to verify that the intergenerational improvement of service architecture can improve system performance brought by technological progress.

Evaluating and accurately modeling unmanned aerial vehicle (UAV) channel model have a significant impact on the design of UAV wireless communication networks. In this pa-per we present an ultra wideband (UWB) channel measurement campaign for low altitude UAV air-to-ground (A2G) scenario. Both line-of-sight (LOS) and non line-of-sight (NLOS) scenarios are considered where the UAV locates at positions with different vertical heights and horizontal places. Based on the channel measurement data, we compare four path loss models to analyze the large scale fading characteristics: the free-space path loss (FSPL) model, the log-distance path loss model (PLM), the 3GPP model and the alpha-beta-gamma (ABG) model. Further, the shadowing fading (SF) is also studied in order to evaluate the impact of blockage by human body on channel characteristics. The result shows that the ABG model has a higher fitting degree, and the maximum shadow fading in the NLOS scenario is twice as much as in the LOS scenario. The conclusion of the paper can be applied in the design and evaluation of UAV communications.

This paper carried out a series of experiments in both the LOS and NLOS scenes, which was based on an unmanned mobile platform, UWB and INS. Throughout experiments, this paper analyzes the ranging error from UWB, verifying that it obeys rice distribution in LOS and lognormal distribution in NLOS respectively; By using TOA combined with GN algorithm, the impact of the number of NLOS links on the positioning error is summarized; Taking the correlation between Links into consideration, their degradation processes was studied; To the end, this paper proposes a DF algorithm based on EKF, whose the positioning error of RMSE is proved to be lower than traditional algorithm.