Applied Mechanics and Materials Vols. 411-414

Abstract: With rapid progress of our society, people put forward higher requirements in speed of wireless communication and method of wireless communication than before. In this paper, the technology of multi-hop relay in wireless communication is illustrated firstly. Then two relay modes of multi-hopamplification-relay and decoding-relay, and relay mechanism are introduced in detail. The implementation of multi-hop system is also analyzed and simulated. At last, the prospect of the technology of multi-hop relay is predicted and expected.

Abstract: Survivability is one of the key issues in Fiber-Wireless (FiWi) access network since a single network component failure may cause enormous data loss. This paper focuses on survivability of citywide FiWi access network and proposes a scheme using Integer Linear Programming (ILP) to tolerate the failures of distribution fiber and WiFi routers considering coverage problem. Simulation shows good performance of this scheme. When WiFi routers and ONUs are places in suitable potential sites, the maximal coverage of uses and survivability of FiWi access network are realized.

Abstract: In this article, we present a new model for distributed intelligent management networks. This paper presents a approach for the design and implementation of a distributed intelligent system that is designed through the normalization of knowledge management. Our study focuses on a language for formalizing knowledge management descriptions and an intelligent framework and combining them with an existing Open Systems Interconnection (OSI) management model. Further, this work outlines the development of an example based on our proposed standard.

Abstract: The Satellite Digital TV Time Service is based on the DVB-S Satellite Digital TV system, using Program Clock Reference (PCR) in the MPEG-2 frame to capture timestamp and measure delay time. This paper, considering the PCR as the Time Synchronization Flag after researching Transport Stream (TS) frame and Asynchronous Serial Interface (ASI) in Satellite Digital TV system, recovers the asynchronous serial data from TS in Satellite Digital TV by oversampling technology. After that, PCR will be found from the recovered data, and the timestamp will be captured when PCR is detected. Finally, this method is tested by using E5710 Encoder and FPGA Cyclone II chip. The experimental results are satisfactory, and the precision of detecting bit synchronization excels 3.7ns.

Abstract: Ultra High Frequency (UHF) band is increasingly widely used in military maritime satellite communications due to its good communication performance. When the electromagnetic wave reaches the sea surface, it is reflected. The reflected wave and direct wave enter the receiver in the form of a superimposed vector, which will inevitably produces multipath fading at the receiving end. This paper followed the general principles of modeling in multipath effects, and the UHF band multipath effects of sea surface were studied. The judgment basis was obtained which determines whether the specula reflected wave dominates in the reflected wave based on Rayleigh criterion, and then the reflection coefficient of sea surface were calculated. Finally, the power attenuation of reflected wave relative to direct wave for different wind speeds were simulated and analyzed.

Abstract: In this paper, we present a compact high-efficiency multi-band micro strip antenna for the mobile devices. At the same time, because most of antennas are located near the ground planar, the proposed antenna is designed with a ground planar. The antenna occupies a small size of 100*60mm2 and operates in CDMA(824-894MHz),GSM(880-960MHz), DCS(1710-1880),PCS(1850-1990),UMTS(1920-2170) and 3G band. By using a long slot, two trapezoid slots and a short slot, a triple resonance around 900MHz and another wideband resonance around 2100MHz can be created, respectively. Details of the antenna design are described , and its radiation performances results are presented and discussed. Keywords-Multi-band antenna;; mobile communication devices; hige-efficency

Abstract: This paper proposes a new handover (HO) Algorithm for LTE high-speed rail networks aiming to reduce time latency during handover and enhance the smoothness of handover in high-speed railway networks. In railway networks, travel environment including the trace and location information of the train and position of the target eNodeB can be precognitive, which can be utilized to receive a fast handover scheme to simplify the system design and increase handover performance. The simulation results show that the proposed scheme has better performance than typical A3 event based handover algorithm in high-speed rail environment.

Abstract: This paper introduces an integrated simulation system for visible light communications (VLC) which is based on DC-biased optical OFDM (DCO-OFDM). By simulating a VLC system with an equalizer, we optimize the parameters for a real-time system: the number of sub-channels and quantization bits. It could be concluded that a 128 sub-channels system is suitable when the signal bandwidth exceeds 100MHz and 6 quantization bits should be enough for a VLC system, which would be useful when it comes to a hardware only system.

Abstract: HD Radio standard can realize the smooth transition from analog to digital using "in-band on-channel (IBOC)" technology, which is the most advantageous choice for analog broadcasting digitized. In HD Radio Hybrid and Extended waveform type, the digital signal employs the same carrier with the analog signal, and is transmitted on both sides of the analog FM signal. Since the digital carrier adjacent analog signal, the core to implement IBOC is the interference problem of digital signal to analog signal at the beginning of broadcasting digitized. For the interference evaluation model, this paper apply noise masking ratio (NMR) and objective evaluation level (ODG) as a combined evaluation factor for digital-analog interference in IBOC broadcasting. This interference evaluation method which utilizes the comprehensive advantages of NMR and ODG, with more scientific than the SNR measurements, can be widely used as an evaluation index for audio interference.

Abstract: A software-based bias control system of push-pull Mach-Zehnder Modulators (MZMs) without dither tone is described in this paper. The slope of the average optical output power respect to the bias voltage is used to control the operating bias points in the automatic control system. The paper analyses the theory of automatic bias control intensively and verifies the effectiveness of the proposed technique which is a modulation-format-free method under the RF signal through testing and contrasting the BER (bit error rate) between the new technique and manual measure on the experimental platform.