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Articles by Lu Zhaogan
Total Records ( 8 ) for Lu Zhaogan
  Lu Zhaogan , Wang Liejun , Zhang Taiyi and Runping Yun
  The combination of Multiple-Input Multiple-Output (MIMO) signal processing with Orthogonal Frequency Division Multiplexing (OFDM) is regarded as a promising solution for enhancing the data rates of next-generation wireless communication systems operating in frequency-selective fading environments. However, when the length of MIMO OFDM symbols is larger than that of wireless channel delay, two intractable issues should be resolved before their applications in cellular fast fading channel scenarios with large numbers of users, i.e., the bandwidth overhead of channel estimation and the challenge to construct large numbers of orthogonal training sequences. So, a new design scheme of training sequence in time domain, is adopted to conduct channel estimation in MIMO OFDM systems, which works as a generations of Steiner method in multi-user CDMA uplink scenarios. Training sequences of different transmit antennas, can be simply obtained by truncating the circular extension of one basic training sequence and the pilot matrix assembled by these training sequences is one circular matrix with good reversibility. Furthermore, when the length of channel profiles is less than that of MIMO OFDM symbols, more bandwidth resources can be saved, as the training sequence only occupies a part of one MIMO OFDM symbol. Numerical results of bandwidth overheads and channel estimations, indicate the proposed method can save abundant bandwidth and achieve good channel estimation accuracy when compared with classical frequency and time domain approaches, respectively.
  Wang Liejun , Jia Zhenhong and Lu Zhaogan
  Support Vector Machines (SVMs) and Multi-Resolution Analysis (MRA) both have been developed for solving signal approximation problem. Replacing the approximation criterion of MRA by which be used in SVMs, multi-resolution signal decomposition and approximation algorithm based on SVMs can be derived. The advantage of this algorithm not only reduces the approximation error by introducing structure risk, but also has better smoothness of approximation function. Experiment illustrates that this algorithm has better approximation performance than conventional MRA when applying it to the approximation of stationary signal.
  Liu Zunxiong , Xu Zheng , Feng Xingle and Lu Zhaogan
  In current 4G system given in recent literatures, channel estimation overhead and complexity of Multi-User Detectors (MUD), may lead to bad performance in fast fading channel scenarios when large number of users exists. So, a novel 4G system with TDD/TDMA as duplex and wireless access is designed to reduce channel estimation spending and avoid MUD, as only one user can be active to communicate with base station. Under the requirement of 4G systems, radio frame structure is elaborately designed to fit for fast fading channel scenarios. The system architecture with consideration of link adaptations for a novel eigenmodes coupled universal space-time codes, is given and evaluated for performance of TDD/TDMA 4G systems. Results show the proposed TDD/TDMA 4G can meet the requirement of 4G system under the classical ITU channel profiles.
  Lu Zhaogan and Liu Long
  Up to now, the dynamic scene echo simulator for radio detector is still difficult to implementation with computer simulation. In this report, one dynamic scene implementation scheme was presented which was based on the radio detector scene models constructed by 3ds Max (3D studio Max) 2010. The idea is that the scene could be set up with more geometric data, material properties and other auxiliary information. Then, the scene must be converted into geometric data files and VRML 97 format files. The two file are actually the data version and VRML version and could be used separately from 3ds Max 2010. Thus, they could be integrated into the simulator constructed by our research project. During the simulation progress, the objects in the scene could have different location and movement states. And, these location and movement information could be updated timely in the geometric data files and VRML 97 scenes. Thus, the dynamic scene could be displayed by most VRML 97 browsers when the simulation last for a period time. At last, the echo simulator of radio detector verified the dynamic scene.
  Lu Zhaogan , Yang Yuye and Wei Qing
  During the design and development of proximity radio detector for proximity detecting in the range about 20 m, various test and debug would be involved with dedicated echo signal. However, it’s difficult to obtain. This study is devoted to the echo signal simulation for the dedicated s. One signal simulation scheme for proximity radio detector is outlined for the signal from dedicated s. According to the signal model of radio detector transceivers, the echo signal is evaluated under the case of dynamic scenes constructed by professional 3 day modeling software. The simulation scheme could realize the independency of scene modeling, movement control and simulating algorithm, and have good generalization and extensibility. The simulator was constructed into an independent echo simulating block, which could be integrated with common used system simulating software. Finally, one simulating instance indicated that the simulated echo waveform could reflect the signal changes during the process of radio detector meetings.
  Lu Zhaogan and Wan Jinliang
  With the wide spread of WiFi hotspot in the area flooded by a lot of populations, i.e., Mall, city squares and railway stations, many WiFi hotspots are deployed by the shop stores and telecommunication providers. However, the concentrated excessive WiFi hotspot would lead to the interfering among the hotspots in the areas and the network speed is slowed down. Here, the network performance in the high density WiFi hotspot areas is analyzed and the relative techniques about interfering cancellation are presented in details. Finally, the possible solutions about WiFi hotspot management as the effective approaches are also proposed in the review.
  Lu Zhaogan and Sun Jiangfeng
  Up to now, the support vector machine theory had been widely used to face detection by reason of its good capability to deal with non-linear high-dimension training problems by small samples. In fact, a large number of facial images were needed to train the support vector machine algorithms, whose complexity were increased by geometric series with training image numbers. So, the hybrid Monte Carlo method and Bayesian support vector machine were combined to find way out for the problems of high-dimension and long training time. The training method of support vector machine was implemented by the hybrid Monte Carlo method. Then, the scheme was verified by experiments that long training time was avoided and good face detection could also be reached.
  Lu Zhaogan and Bao Zhiguo
  By the reasons of the bad accuracy of drawbacks of current image searching algorithms, the difficulties and uncertainties of image blocking procedures, one image searching algorithm with the partition of multiple scales and levels is proposed in this study, which is conducted by the classic wavelet multiple scale and level decomposition algorithm. According to the algorithm, the interest objects would be found in the image partitions at different levels with different scales, where the Gabor texture features, main colors and color invariant moments were used as the metric of image searching results. Based the numerical evaluation results with classical histogram and invariant moment approaches, the image searching accuracy is improved from 66 and 68-77% by the algorithm with feasible implementation.
 
 
 
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