Advanced Materials Research Vols. 791-793

Abstract: In this article we focus on SIP session setup delay .It bases on adaptive RLP retransmission mechanism in the previous paper.It proposes a way used RLP retransmission strategy combined with the performance of wireless channels, that i s to say in different chain Road conditions use different RLP retransmission strategy approach. This method not only can complete the RLP adaptive retransmission of SIP messages at the link layer, and can select the appropriate link status of the different RLP retransmission strategy, thus effectively shortening the SIP session establishment delay, end to end QoS for IMS performance improvement. After a simulation experiment, the effectiveness of the proposed algorithm is tested.

Abstract: Image processing is a type of memory-access-intensive application which puts a great pressure on memory access speed and bandwidth. Memristors has the ability of both memory and computing. With this property, we have designed and implemented image logic operations in memristor memory system, which could save a large amount of memory access at relatively low memory space price. Based on this work, we use image logic operations with memristors into edge detection of binary image. The main idea is as follows. First, we use XOR operation of neighboring pixels to determine whether there is an edge and get the vertical edges and horizontal edges, respectively. Then, we combine the edges in two directions to obtain the whole edge image of the original image. The experimental results show that, our design is right in function, and could reduce memory access considerably.

Abstract: Authentication is the process where claims of identity are verified. Most mechanisms of authentication exist above the physical layer, though some exist at the physical layer often with an additional cost in bandwidth. This paper introduces a general analysis and design framework for authentication at the physical layer where the authentication information is transmitted synchronously with the data. By superimposing a carefully designed secret modulation (wavelet transform) on the waveforms, authentication is added to the signal without requiring additional bandwidth. Simulation results are given that demonstrate the potential application of this authentication technique.

Abstract: In the low earth orbit (LEO) satellite communication systems, in which receiver and transmitter are not fixed and have significant relative velocity, the fast time-varying Doppler frequency shift is high, which degrades the performance of acquisition and tracking. Doppler frequency shift and Doppler frequency rate can be calculated by the terrestrial system based on the satellite orbit and the relative velocity. In this paper, we introduce the Doppler compensation principle and the realization of Doppler shift estimation and compensation on an universal wireless signal processing platform. The experimental results showed that the Doppler compensation model have high accuracy, which is positively correlated with the Doppler frequency rate.

Abstract: In modern LEO satellite communication systems, numerous singnals have to be located in a same frequency band because of limited spectrum resources. Thus, a bandwidth-efficient modulation, which has constant envelope characteristics and can alleviate signal distortions when using saturated power amplifiers is necessary to combine several signals to share the frequency resource. This paper presents the analytic interplex modulation expression in LEO satellite spread spectrum communication systems, and obtains the relationship of modulation efficiency, error rate and power ratio. Lastly, the appropriate choice of power radio is obtained in the case of three signals or four signals multiplexing. The work of this paper is an important guideline for constant envelope combined methodologies in LEO satellite spread spectrum communication systems.

Abstract: We focus on the recognition of RS code in a reverse-engineering communication system, and an algorithm based on spectral statistic is proposed, which makes use of the spectral characteristics of RS code. When there are some codes with errors in the observations, the spectral histogram statistic is computed, which can improve the probability of detection in the noisy environment. Experimental results are given to illustrate the performances of the method which can get a 90% probability of detection of (255, 223) RS code in the presence of 0.5% code error rate.

Abstract: Proposed a robust adaptive beamforming algorithm for the beamformers performance degradation in high Signal-to-Noise Ratios (SNRs), which is based on interference covariance matrix reconstruction and steering vector estimation. The simulation results prove the effectiveness.

Abstract: The prosperity of the Chinese art market promoted the spiritual and cultural development. However, counterfeit, fake artworks often happen. After in-depth analysis of the characters of the two-dimensional code and current artworks anti-counterfeiting technology, and combined with the characteristics of ceramic art, an efficient ceramic artworks anti-counterfeiting and authentication method was proposed based two-dimensional code and WAP technology. Art-related information with a random code was built dynamic encryption security sequence, and consumer can use a phone quickly and efficiently achieve certification of ceramic artwork via WAP. The performance analysis shows that this method is feasible and easy to implement, maneuverability, and safety.

Abstract: Assessing the complexity degree of electromagnetic environments (EME) is a typical pattern recognition problem. Feature extraction is the most significant step for EME complexity classification tasks. In his work, a novel feature extraction scheme for EME complexity classification scheme based on non-negative matrix factorization (NMF) is presented. EME signals with four complexity degree are simulated to evaluate the effectiveness of the presented method. Experimental results reveal that the NMF based features to be desirable indices for accurate complexity degree evaluation of EME.

Abstract: Mission planning system is one of the essential equipment for unmanned aerial vehicles task implementation. The development of mission planning system is necessary for the improvement of the efficiency and safety of the unmanned aerial vehicles. Comparing with foreign advanced mission planning system, this area in China is relatively undeveloped. This article focuses on the analysis of some of the key technical content of the overview of the development of the foreign mission planning, trying to provide reference to China's development of mission planning system.