Improvement of Return Loss Bandwidth of Balanced Amplifier Using Metamaterial-Based Quadrature Power Splitters

A new balanced amplifier (BA) using metamaterial-based quadrature power splitters (QPSs) is presented in this letter. Instead of using conventional 90 couplers, the developed BA is implemented by two parallel amplifiers with broadband metamaterial-based QPSs at input and output ends. Since the QPSs can provide a broadband quadrature phase difference between two outputs, the input/output reflections from two amplifiers can be effectively cancelled over a wide bandwidth. The developed BA demonstrates the input/output return loss of better than 10 dB from 1.2 to 3.5 GHz with 97.9% relative bandwidth.     

PCS mobility management using the reverse virtual call setupalgorithm

The increased demand for wireless mobile communications coupled with the finite available spectrum has motivated investigation into alternative methods of tracking users and delivering calls. We present a new scheme for delivering mobile terminated calls named reverse virtual call setup (RVC). Only a few new fixed network SS7 signaling messages are needed to implement this protocol; we specify them here. RVC can function within the existing cellular paging network or with an integrated overlaid paging network. The relative performance of RVC for both scenarios is investigated     

Analog diversity coding to provide transparent self-healingcommunication networks

pg 100 diversity coding, as introduced in Ayanoglu et al. (1990), is a method of protection against failures in a communication network or a storage system, which is based on introducing a digital error-correcting code across independent links. This technique makes efficient use of the extra network capacity needed for coding and has the additional advantages of being nearly instantaneous, not requiring a feedback channel, rerouting, or resynchronization. In high-speed (multi Gbps) networks, digital coding will be difficult to implement, and the purpose of the present paper is to demonstrate how diversity coding may be implemented in the analog domain using the discrete fourier transform (DFT). In particular, the authors show that the DFT is a continuous-amplitude maximum-distance separable code over the field of complex numbers when the transform kernel is a prime root of unity. This code can be used to generate self-healing or fault-tolerant communication networks for continuous- or discrete-amplitude signals, as long as continuous-amplitude parity channels are available. The authors describe electrical and optoelectronic implementations, and a signal estimation approach to combat channel noise and thereby improve the performance of the analog diversity coding system. The most important advantage of this technique is in greatly simplifying the encoders and decoders of diversity coding systems for high-speed networks, such as fiber-optic wavelength division multiplexed networks. Application of analog diversity coding to systems with analog sources, such as telemetry systems is also possible     

工业无线光技术研究进展

现有的绝大部分应用于各类工业环境无线解决方案是基于传统射频的技术范式,存在电磁干扰、工业数据泄露等潜在风险,众多研究机构正积极地将多样的无线光技术引入到工业智能场景.为了清晰阐述无线光技术在工业场景应用的研究进展,分别从工业无线光多载波传输、多输入多输出(MIMO)传输、定位和原型通信系统实验这些方面进行了梳理,初步给...     

Adaptive information dissemination: an extended wireless data broadcasting scheme with loan-based feedback control

The dissemination of numerous information broadcast services, gives rise to the scalability issue in wireless networks. Previous researchers have shown that the push-based data broadcast mechanism is efficient in reducing message traffic. However, most research efforts are dedicated to the dissemination of static information contents. In practice, information broadcast services can produce and deliver dynamic information contents. To efficiently convey the dynamic data, we device, in this paper, an adaptive information dissemination mechanism by exploiting the functionality of data broadcasting, to support the dissemination of static and dynamic information services simultaneously. In our design, both static and dynamic information services are subsumed as service groups, i.e. the building blocks with the uniform representation of structure and group popularity and, thus, the conventional scenario becomes a special case of our framework. Furthermore, in order to tolerate the broadcast traffic dynamics, we design an online load-based slot allocation and feedback control technique to deal with the adaptation of the service group classification, bandwidth allocation, and broadcast schedule so as to avoid performance degradation. It is shown by the experimental study that the proposed adaptive information dissemination mechanism associated with the online loan-based feedback control is able to achieve a substantial reduction of message traffic for dynamic dissemination in wireless networks.     

On construction of a distributed data storage system in cloud

In the past, people have focused on cluster computing and grid computing. Now, however, this focus has shifted to cloud computing. Irrespective of what techniques are used, there are always storage requirements. The challenge people face in this area is the huge amount of data to be stored, and its complexity. People are now using many cloud applications. As a result, service providers must serve increasingly more people, causing more and more connections involving substantially more data. These problems could have been solved in the past, but in the age of cloud computing, they have become more complex. This paper focuses on cloud computing infrastructure, and especially data services. The goal of this paper is to implement a high performance and load balancing, and able-to-be-replicated system that provides data storage for private cloud users through a virtualization system. This system extends and enhances the functionality of the Hadoop distributed system. The proposed approach also implements a resource monitor of machine status factors such as CPU, memory, and network usage to help optimize the virtualization system and data storage system. To prove and extend the usability of this design, a synchronize app was also developed running on Android based on our distributed data storage.     

Message estimation for universal steganalysis using multi-classification support vector machine

To prevent misusing of the steganography from the terrorists, effective steganalysis schemes which discriminate the stego-images from suspicious images are necessary. Some steganalysis methods can accurately estimate the length of embedded messages but they are only useful in the pre-defined condition. Active steganalysis methods are powerful in length estimation such as regular singular (RS) and sample pairs analysis (SPA) steganalysis schemes, but they would become invalid in frequency domain. Passive steganalysis methods may discriminate stego-images from suspicious images in spatial and frequency domains such as Lyu and Fraid's steganalysis scheme, but they could not estimate the length of hidden messages. Although length estimation has been discussed in the active steganalysis methods for a while, it is a novel study in passive steganalysis method. We improve the Lyu and Fraid's universal steganalysis scheme and design an efficient length estimation policy in passive steganalysis methods. Experimental results demonstrate the efficiency and practicability of the proposed universal steganalysis scheme.