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Listen-Before-Talk category 4 (LBT Cat4) mechanism is considered as the most appropriate access method for Licensed-Assisted Access (LAA) framework, especially when LAA system coexists with WiFi system in unlicensed bands. Previous investigations of the LBT Cat4 based LAA-WiFi coexistence provide experimental results and simulation results, and theoretical analysis work is relatively rare. This work...
In this paper, we propose 3DLoc, which performs 3-dimensional localization on the tagged objects by using the RFID tag arrays. 3DLoc deploys three arrays of RFID tags on three mutually orthogonal surfaces of each object. When performing 3D localization, 3DLoc continuously moves the RFID antenna and scans the tagged objects in a 2-dimensional space right in front of the tagged objects. It then estimates...
Listen-Before-Talk (LBT) is the clear channel assessment (CCA) check method of Licensed-Assisted Access (LAA) framework. A flexible LBT strategy is important when LAA devices coexist with WiFi system in unlicensed spectrum. The existing adaptive LBT methods modify the LAA contention window (CW) size according to information exchanged between the coexisting two systems. This work proposes an adaptive...
The centralization of control plane in Software defined networking (SDN) creates a paramount challenge on troubleshooting the network as packets are ultimately forwarded by distributed data planes. Existing path tracing tools largely utilize packet tags to probe network paths among SDN-enabled switches. However, network functions (NFs) or middleboxes, whose presence is ubiquitous in today's networks,...
This paper proposes the methods of high intensity radiated field (HIRF) testing for civil aircraft. It introduces how to eliminate the background noise and select the frequency list for HIRF testing at first. Then, the method of LLSC calibration and LLSC test is proposed along with an automatic test system of LLSC testing. After that, how to design a mode stirrer and validate the performances of it...
Recently, wearable electronic devices have drawn increasing attentions because of the merits of high flexibility and stretchability and could be used to sense tactility, vibration, and temperature. It has been widely used in the humanoid robotics, mobile phones, and physical/chemical sensors and even human body in the past few years. Therefore, it is essential to develop pressure sensors with high...
We designed and developed a Ubiquitous Geometry (UG) app for elementary school students to learn geometry in authentic contexts. Real geometry object could facilitate and consolidate students' geometry learning if students were given opportunities to apply and practice geometric concepts in authentic contexts. Geometry is one of the important subject, however, students have less opportunities to apply...
Flexible electronics has emerged as an independent field and became increasingly popular over the past decades because of they can provide a lot of benefits compared to traditional rigid printed circuit boards, such as better durability, lighter weight, higher space efficiency, and improved comfort. Conductive polymer composites (CPCs) especially which possess flexibility and printability are very...
Robust adaptive time-varying formation control problems for high-order linear multi-agent systems with parameter uncertainties and external disturbances are investigated. Firstly, using the adaptive updating mechanism, a fully distributed time-varying formation control protocol is proposed. The protocol is determined by each agent in a fully distributed form and does not need any global information...
The research field of mental workload has attracted abundant researchers as mental workload plays a crucial role in real-life performance and safety. While previous studies have examined the neural correlates of mental workload in 2D scenarios (i.e., presenting stimuli on a computer screen (CS) environment using univariate methods (e.g., EEG channel power), it is still unclear of the findings of one...
With the popularization of human-carried devices, it is possible for Mobile Crowd Sensing (MCS) applications to perform large scale sensing with sensors embedded in these devices. Many incentive mechanisms for MCS applications have been proposed due to the importance of attracting more worker to participate. However, these mechanisms failed to consider situations where there are constraints on both...
This paper investigates two finite-time attitude tracking controllers for spacecraft with attitude dynamics presented by rotation matrix. With the use of rotation matrix, unwinding problem widely exists in controllers based on quaternion can be dealt with. Based on backstepping method, the first controller can be developed in the presence of external disturbance. However, the upper bound of the disturbance...
In the reentry stage, the hypersonic gliding vehicle (HGV) has the obvious characteristics like high-dynamic, large flight envelop, complex flight environment and so on. These features result in severe parameter uncertainties. In order to improve the attitude control performance in reentry stage, the sources of the uncertainty and the unknown parameters are analyzed. Then a robust adaptive controller...
In recent years, surveillance videos are playing an important role in modern security systems. As a state-of-the-art video coding standard, High Efficiency Video Coding (HEVC) has been deployed in many surveillance cameras. Nevertheless, the request of real-time and high subjective quality coding still poses the great challenging problem of efficient representation and compression for high complexity...
In this paper, we analyze uplink sum rate of multiple-input multiple-output (MIMO) systems with maximum-ratio combining (MRC) receivers. To be practical, receive correlation and different powers of users are assumed. Two novel approximate results on sum rate are derived in closed form. Based on the results, we also obtain the asymptotic results on sum rate when the number of base station antenna (M)...
Licensed-Assisted Access Long-Term Evolution (LAA- LTE) framework can offload excessive data stream to the unlicensed spectrum. Devices from different operators will compete for the same band and have to endure a more complex and congested channel conditions. Therefore a rapid and efficient access mechanism should be introduced in the LAA framework. Based on the Type B LBT channel access scheme, this...
This paper considers the BBU computing resource allocation problem in a C-RAN system. In particular, we consider the additional computing resource consumption introduced for coordination between different BBUs when the tasks of a cell is processed by different BBUs and consider load balancing among multiple BBUs in order to reduce the effect of a breakdown BBU on the system. The problem is formulated...
A novel multi-dimensional nanostructure constructed with three types of nano-building-block is used as electrochemical sensing material to detect trace dopamine which plays as neurotransmitter in body-fluids. For the multi-dimensional multi-level sensing nanostructure construction, nanosheet of graphene oxide (GO) is herein served as nano-substrate. By using hydrothermal method, ZnO nanowires are...
In this paper, a novel +45° insulator is proposed. The insulator has a conductivity graded structure in which the high conductivity part performs as a shield to reduce the electric field concentration at anode triple point and along surface. Hence, the surface electrical withstanding strength would be enhanced. Computer aided simulation is performed to investigate the electric field distribution with...
Two sliding-mode based fault tolerant control schemes are proposed for attitude dynamic tracking problem of re-entry reusable launch vehicle (RLV) under actuator fault, unknown uncertainty, external disturbances, and input limitation. Firstly, the mathematical model of reentry RLV with loss of actuator effectiveness fault is presented. Then, a novel control algorithm is provided for stable control...
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