Research on multipoint transmission protocols for wireless sensor network

制度:新 ; 報告番号:甲3771号 ; 学位の種類:博士(工学) ; 授与年月日:2013/2/18 ; 早大学位記番号:新6144Waseda Universit

Cross-border E-commerce Development Strategy Under the Internet + Logistics Finance Model

In recent years, the rise of cross-border e-commerce in China has been relatively rapid, and the proportion of cross-border ecommerce in import and export trade has continued to increase. Cross-border e-commerce plays an extremely important role in promoting China\u27s trade transformation and has become a new model of international trade. But the prosperity of any field is inseparable from the strong support of funds. This paper identifies the risk factors that may arise when cross-border e-commerce applications are applied to these models. Then analyzes and evaluates them in order to provide decision-making reference for cross-border e-commerce enterprises that have financing needs or plan to apply logistics finance

Fast antijamming timing acquisition using multilayer synchronization sequence

Pseudonoise (PN) sequences are widely used as preamble sequences to establish timing synchronization in military wireless communication systems. At the receiver, searching and detection techniques, such as the full parallel search (FPS) and the serial search (SS), are usually adopted to acquire correct timing position. However, the synchronization sequence has to be very long to combat jamming that reduces the signal-to-noise ratio (SNR) to an extremely low level. In this adverse scenario, the FPS scheme becomes too complex to implement, whereas the SS method suffers from the drawback of long mean acquisition time (MAT). In this paper, a fast timing acquisition method is proposed, using the multilayer synchronization sequence based on cyclical codes. Specifically, the transmitted preamble is the Kronecker product of Bose–Chaudhuri-Hocquenghem (BCH) codewords and PN sequences. At the receiver, the cyclical nature of BCH codes is exploited to test only a part of the entire sequence, resulting in shorter acquisition time. The algorithm is evaluated using the metrics of MAT and detection probability (DP). Theoretical expressions of MAT and DP are derived from the constant false-alarm rate (CFAR) criterion. Theoretical analysis and simulation results show that our proposed scheme dramatically reduces the acquisition time while achieving similar DP performance and maintaining a reasonably low real-time hardware implementation complexity, in comparison with the SS schem