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Copyright of Hydrographic Surveying & Charting / Haiyang Cehui is the property of Hydrographic Surveying & Charting Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel dynamic bandwidth management mechanism based on the traffic prediction is presented to solve the problem of long delay caused by traditional demand assigned multiple access (DAMA). Firstly, the satellite terminals predict the queue length of the buffer, then send the reports to the network control center (NCC). Finally, the resources are allocated to the terminals by NCC. The algorithm performance is validated through the simulation for different types of traffic and different intervals between two consecutive prediction reports. The priority of real time traffic is considered. The delays of DAMA based on prediction and normal case are compared. The theoretical analysis and simulation results show that the new DAMA algorithm can efficiently tackle the problem of delay between bandwidth request and bandwidth assignment. [ABSTRACT FROM AUTHOR]

Radio over fiber (ROF) techniques could achieve ultra-wide wireless access and wired- line transmission of RF signal with high-capacity and low cost. The millimeter-wave modulator with wide bandwidth is the most important device in ROF system. This paper describes the design and manufacture process of the dual-parallel Mach-Zehnder modulator (DPMZM). To reduce the direct current (DC) shift and thermal drift, a particular electrode structure has been chosen, which applies selective corrosion to strip off most part of SiO2 buffer except the SiO2 just under the hot electrode. The tested parameters of sample DPMZM are as follows. The characteristic impedance is 35Ω, the insert loss is 7.2 dB, the extinction ratio is 26 dB, the half-wave voltage is 3.0 V when single arm is driving or 1.5 V when two arms are driving, and the modulate bandwidth is about 20GHz. It is obvious that, except for the bandwidth, the performance of fabricated modulator has the same (or higher) level as the high quality products manufactured in the international market. The fabrication of LiNbO3 DPMZM has not been reported by the domestic organization so far. [ABSTRACT FROM AUTHOR]

This study provided quantitative analyses from several aspects of signal timing related to bandwidth optimization, including: the influence of signal phasing sequence, the impact of intersection spacing, and the impact of number of signals in a system. A large number of arterial scenarios were randomly generated to simulate 90 000 traffic signal systems that likely exist in the real world. After comparing the effectiveness of four phasing sequences, it was concluded that lead-lag or lag-lead phasing sequence was used 5% more than leading or lagging. The impact of intersection spacing was analyzed by comparing uniformly and randomly spaced signal systems. Uniformly spaced signal systems did not provide better progression bandwidth than non-uniformly spaced systems. The study also found that the number of signals had a significant impact on bandwidth attainability. When the number of intersections exceeded 16, there were practically no two-way bandwidth solutions, suggesting that bandwidth based signal timing approach may not be feasible. [ABSTRACT FROM AUTHOR]

Bandwidth of non-Gaussian signals and noises in practical applications is narrow. If simply using correlation algorithm in traditional Gaussian model to estimate the multipath time delays, peak values will overlap each other. So it will bring on large estimate errors. To solve this problem, according to the characteristics of signal and noise and the theory of the fractional lower order statistics, a super resolution multipath time delay estimation algorithm referred to P-EM is proposed. It is based on the EM (expectation-maximization) algorithm using the pth-order correlation and can be applied under α-stable distribution noise. It is shown that the proposed approach is robust through the theoretical analysis and the computer simulations. [ABSTRACT FROM AUTHOR]