The engineering vision of relying on the "smart sky" for supporting air traffic and the "Internet above the clouds" for in-flight entertainment has become imperative for the future aircraft industry. Aeronautical ad hoc Networking (AANET) constitutes a compelling concept for providing broadband communications above clouds by extending the coverage of Air-to-Ground (A2G) networks to oceanic and remote airspace via autonomous and self-configured wireless networking amongst commercial passenger airplanes. The AANET concept may be viewed as a new member of the family of Mobile ad hoc Networks (MANETs) in action above the clouds. However, AANETs have more dynamic topologies, larger and more variable geographical network size, stricter security requirements and more hostile transmission conditions. These specific characteristics lead to more grave challenges in aircraft mobility modeling, aeronautical channel modeling and interference mitigation as well as in network scheduling and routing. This paper provides an overview of AANET solutions by characterizing the associated scenarios, requirements and challenges. Explicitly, the research addressing the key techniques of AANETs, such as their mobility models, network scheduling and routing, security and interference are reviewed. Furthermore, we also identify the remaining challenges associated with developing AANETs and present their prospective solutions as well as open issues. The design framework of AANETs and the key technical issues are investigated along with some recent research results. Furthermore, a range of performance metrics optimized in designing AANETs and a number of representative multi-objective optimization algorithms are outlined.

In order to deploy minimum number of unmanned aerial vehicle (UAV)-mounted mobile base stations (MBSs) to service all given ground terminals, this paper proposes an MBS placement based on sparse recovery (MBS-PBSR) algorithm. By exploiting the sparsity inherent in the differences between any two dedicated MBSs, the problem of UAV-mounted MBS placement could be formulated as an 0-norm constrained optimization problem, which is then be solved by the reweighted 1-norm method. Subsequently, the resulted solutions to the MBS placement are adjusted by the iterative redundant circle deletion algorithm, eventually leading to the redundant MBSs removal as much as possible. Simulation results demonstrate that our proposed MBS-PBSR algorithm works well with affordable computational complexity, and is nearly optimum in the sense of the number of deployed UAV-mounted MBSs. INDEX TERMS Unmanned aerial vehicle, mobile base station, sparse recovery.

Abstract-Recent research has shown that tests generated without taking process variation into account may lead to loss of test quality. At present there is no efficient device-level modeling technique that models the effect of process variation on resistive bridges. This paper presents a fast and accurate technique to model the effect of process variation on resistive bridge defects. The proposed model is implemented in two stages: firstly, it employs an accurate transistor model (BSIM4) to calculate the critical resistance of a bridge; secondly, the effect of process variation is incorporated in this model by using three transistor parameters: gate length (L), threshold voltage (V ℎ ) and effective mobility ( ), where each follow Gaussian distribution. Experiments are conducted on a 65-nm gate library (for illustration purposes), and results show that on average the proposed modeling technique is more than 7 times faster and in the worst case, error in bridge critical resistance is 0.8% when compared with HSPICE.Index Terms-Resistive bridge fault, process variation, fault model, deep-submicron defect.

Abstract-This paper shows that existing delay-based testing techniques for power gating exhibit fault coverage loss due to unconsidered delays introduced by the structure of the virtual voltage power-distribution-network (VPDN). To restore this loss, which could reach up to 70.3% on stuck-open faults, we propose a design-for-testability (DFT) logic that considers the impact of VPDN on fault coverage in order to constitute the proper interface between the VPDN and the DFT. The proposed logic can be easily implemented on-top of existing DFT solutions and its overhead is optimized by an algorithm that offers trade-off flexibility between test-application-time and hardware overhead. Through physical layout SPICE simulations, we show complete fault coverage recovery on stuck-open faults and 43.2% testapplication-time improvement compared to a previously proposed DFT technique. To the best of our knowledge, this paper presents the first analysis of the VPDN impact on test quality.

A transmit antenna selection (TxAS) aided multi-user multiple-input multiple-output (MU-MIMO) system is proposed for operating in the MIMO downlink channel environments, which shows significant improvement in terms of higher data rate when compared to the conventional MU-MIMO systems operating without adopting TxAS, while maintaining low hardware costs. We opt for employing a simple yet efficient zero-forcing beamforming (ZFBF) linear precoding scheme at the transmitter in order to reduce the decoding complexity when considering users’ side. Moreover, considering that users within the same cell may require various qualities of service (QoS), we further propose a novel user-oriented smart TxAS (UOSTxAS) scheme, of which the main idea is to carry out AS based on the QoS requirements of different users. At last, we implement the proposed UOSTxAS scheme in the software defined radio (SDR) MIMO communication hardware platform, which is the first prototype hardware system that runs the UOSTxAS MU-MIMO scheme. Our results show that, by employing TxAS, the proposed UOSTxAS scheme is capable of offering higher data rates for priority users, while reasonably ensuring the performance of the common users requiring lower rates both in simulation and in the implemented SDR MIMO communication platform.

In the 5G intelligent edge scenario, more and more accelerator-based single-board computers (SBCs) with low power consumption and high performance are being used as edge devices to run the inferencing part of the artificial intelligence (AI) model to deploy intelligent applications. In this paper, we investigate the inference workflow and performance of the You Only Look Once (YOLO) network, which is the most popular object detection model, in three different accelerator-based SBCs, which are NVIDIA Jetson Nano, NVIDIA Jetson Xavier NX and Raspberry Pi 4B (RPi) with Intel Neural Compute Stick2 (NCS2). Different video contents with different input resize windows are detected and benchmarked by using four different versions of the YOLO model across the above three SBCs. By comparing the inference performance of the three SBCs, the performance of RPi + NCS2 is more friendly to lightweight models. For example, the FPS of detected videos from RPi + NCS2 running YOLOv3-tiny is 7.6 times higher than that of YOLOv3. However, in terms of detection accuracy, we found that in the process of realizing edge intelligence, how to better adapt a AI model to run on RPi + NCS2 is much more complex than the process of Jetson devices. The analysis results indicate that Jetson Nano is a trade-off SBCs in terms of performance and cost; it achieves up to 15 FPSs of detected videos when running YOLOv4-tiny, and this result can be further increased by using TensorRT.

In recent years, antenna selection (AS) has become one of the most popular research topics for massive multiple-input multiple-output (MIMO) system due to its capability of reducing the number of radio frequency chains utilized for MIMO communications, while remaining the MIMO advantages, such as increased bandwidth efficiency and reliability. In this paper, an efficient norm-based AS (NBAS) algorithm is investigated and implemented in the software defined radio (SDR) MIMO communication platform, which consists of field-programmable gate arrays (FPGAs). Owing to the high freedom and fast reconfigurable FPGA hardware, the SDR MIMO communication platform is capable of developing prototype of NBAS-aided MIMO system. More specifically, the implemented NBAS aided SDR MIMO system is capable of achieving uplink communication from users to the base station via time division duplex (TDD). A time-varying fading channel generation model is designed for SDR MIMO platform to enrich our experimental results. Additionally, a novel multiplexer (MUX) circuit module is designed and implemented to enhance the hardware performance of the FPGA in term of delay and resource usage. The results show that by implementing the low-complexity NBAS, the channel capacity performance of the SDR MIMO system can be significantly improved by around 15%. It is also showed that our proposed optimized MUX circuit intellectual property may reduce the critical path delay by about 2.16 ns, and save at lease 3% hardware resources in SDR FPGA. INDEX TERMS Multiple-input multiple-output, antenna selection, software defined radio, FPGA.

Abstract-Recent research has shown that tests generated without taking process variation into account may lead to loss of test quality. Using transition delay test, this paper analyzes the behavior of resistive bridge defect under the influence of process variation. The effect of process variation is incorporated by using three transistor parameters: gate length (L), threshold voltage (V th ) and effective mobility (µ ef f ), where each follows Gaussian distribution. Through HSPICE simulations using a 65-nm gate library, this paper brings the following two contributions: firstly, it analyzes the delay behavior of bridge defect using all three transition delay classes to determine the most effective class of transition test that achieves maximum coverage in the presence of process variation. Secondly, recent research has shown that lowvoltage testing improves detectability of bridge fault; this work compares bridge resistance coverage using logic test and delay test at multiple voltage settings to identify the best voltage setting and test type for detecting resistive bridge defects.Index Terms-Resistive bridge defects, transition delay test, process variation, logic test, low voltage test.