Applied Mechanics and Materials Vols. 336-338

Abstract: In the "12th Five-Year Plan" period, government will continue to promote the construction of Intelligent Electric Grid , and the construction of more efficient electric power communication access network will also go into the extensive stage from partial stage. But as so far, a large number of public network devices are applied in power communication system, so the equipment’s security is one important issue. This paper analyze the situation of electric power communication access network firstly, and then introduce our specific work in some one device’s security, such as user authentication protocol, the hand-in-hand protection of EPON, and devices’ EMC.

Abstract: Considering the DC-ARQ mechanism, this paper discussed the information transmission cycle of between vehicle nodes in the vehicle and road environment, and obtained the analytical expression of delay performance for GBN-ARQ retransmission protocol. The results obtained in the paper provide a way to improve vehicle ad-hoc network transmission capacity.

Abstract: As the low-band is more and more crowded, moving to Ka-band for the satellite-ground measurement and communication is preferred in the literature. This paper aims to contribute to the understanding of the influence of the atmosphere on the range error and the attenuation in Ka-band. By adopting the method recommended by ITU-R, we analyze the delay range error and the attenuation induced by the ionosphere and troposphere for Ka-band. The result shows that the ionosphere delay range error is significantly reduced in Ka-band comparing with navigation band. The maximal ionosphere delay range error is about 1m in Ka-band. The troposphere delay range error in Ka-band is the same as that in navigation band. When the elevation angle is over 40º, the troposphere delay range error become flat and doesnt exceed approximately 4 m. With respect to atmospheric attenuation, two important findings are obtained: firstly, when the elevation angle is over 40º, the atmospheric attenuation doesnt change significantly and is generally below 2 dB. Secondly, the atmospheric attenuation reaches its peak at the frequency of approximately 22.5GHz in Ka-band. Finally, an important conclusion can be drawn that in the design of the Ka-band satellite-ground measurement system, it should be considered to make the system work at the elevation angle over 40º. Thus, in generally, the range error doesnt exceed 5 m and the attenuation doesnt exceed 2 dB, even though it doesnt make the model correction.

Abstract: Signal detection is a key enabler of cognitive radio. This paper considers the detection signals in uncertain low SNR environments. We propose a feature detector based on cyclic autocorrelation function of signal. Compared with other feature detector based on cyclic spectral, the proposed detector need lower computational cost than computational cyclic spectrum. Similar radiometer detector,SNR wall also exists in noise power uncertainty model. Beyond this SNR wall robust detection is impossible.Detection performance including the SNR wall is proved.

Abstract: CMMB technology employs Orthogonal Frequency Division Multiplexing (OFDM) modulation with 4096 subcarriers for 8MHz bandwidth mode, HPA in the CMMB repeater will cause significant distortion and spectral extension. To compensate HPA nonlinearity and memory effect in a CMMB repeater system, this paper proposed a pre-distortion scheme based on RNN and Bayesian Regularization for the first time. Computer simulation is used to confirm the validation of the proposed scheme and an adjacent channel leakage ratio (ACLR) improvement of 20 dB is obtained in the paper.

Abstract: Because of the security vulnerabilities of the GSM network short message communication faces threat of information theft, this paper propose an end-to-end secure communication solution, then elaborate the security of the scheme, introduce the features and system-level architecture. And implement system based on the Iphone4 platform.

Abstract: This paper introduces the signal data acquisition method of the FSK signal using NI equipment in the track circuit system, and the FSK signal modulation demodulation based on LabVIEW . The track circuit communication detection device for Shanghai metro line 2 provided effective means, saved maintenance costs, created the economic benefit and laid the foundation for subsequent signal detection. solved the problem that without special equipment detection in wayside, it can also realize the results of detection intuitively and the quantitative analysis of technical index

Abstract: With the rapid growth of the demand for wireless data services, it becomes a hotspot in the field of mobile communication to maximize data transfer rate on the limited bandwidth. Link adaptation technology has a strong advantage in improving the data transfer rate and the spectrum utilization rate, thus becoming one of the key technologies in current and future mobile communication systems. This paper aims to study the adaptive technology of the wireless link, emphasizing on the basic principles and existing implementations of the adaptive modulation and coding (AMC) and the hybrid-automatic repeat request (HARQ) which are both mainstream link adaptive technologies. Finally, a new link adaptation technology implementation is given by combining the advantages of AMC and HARQ.

Abstract: The SoC design is a tendency which the navigation and positioning receiver circuit design, its key technologies, including bus architecture technology, IP core design and multiplexing, in which the correlator IP core design and reuse is crucial for navigation and positioning receiver. This paper describes the operating principles and structures of the SoC bus architecture and navigation-positioning correlator, and the various modules of the correlator and the Galileo/GPS navigation signal are analyzed; On this basis, to design Galileo/GPS dual-mode correlator IP core using SoC-based IP core design method, and to simulate and analyse, it can be easily applied to the navigation and positioning receiver baseband SoC design.

Abstract: This paper put forward a research of the chirp signal and its generated method. The research was based on a software-defined radio (SDR) system, which was composed of GNU Radio and Universal Software Radio Peripheral (USRP). It introduced the chirp signal and design algorithm to show how to generate the chirp signal based on DDS technique. And it provided two platforms including the FPGA platform and SDR platform to generate the chirp waveforms. Finally, it analyzed the difference between the two platforms. From the waveforms using these two platforms displayed in oscilloscope, it found that the results based on SDR were better. And it demonstrated that advantages of GNU Radio and USRP.