Wang Hong-yuan

A Heuristic Greedy Optimum Algorithm for Target Coverage in Wireless Sensor Networks

In order to maximize the network lifetime for target coverage, we propose a Heuristic Greedy Optimum Coverage Algorithm (HG-OCA). In HG-OCA, we first design a network model in which power supplies of sensor nodes follow a normal distribution. Next, we analyze energy model of target coverage, educe three rules to reduce network scale, present the concept of the key target and the prior coverage of key target. Moreover, we choose sensor with most energy utility as active sensor. In the end, we present HG-OCA to extend network lifetime, based on minimizing energy consumption of key target and maximizing energy efficiency of sensor node. Measurement results show that the new algorithm could increase 80% longer network lifetime and achieve more adaptability and stability.

An Improved MUSIC Algorithm Implemented with High-speed Parallel Optimization for FPGA

This paper proposes an improved MUSIC algorithm with high-speed parallel optimization for FPGA. Although MUSIC algorithm is a high-performance, classic DOA method, it needs estimation and eigenstructure decomposition of covariance matrix, which is time-consuming with high computation cost and not suitable for FPGA implementations. In this paper, the authors present an optimization algorithm without the eigenstructure decomposition of the covariance matrix. This algorithm offers far lower computation cost compared to MUSIC at the expense of little performance decrease. With parallel preprocessing focusing on correlation matrices estimation and spectral peak search, an FPGA implementation is introduced, and proved to be efficient through theoretical analysis, simulation and hardware implementation.

High resolution DBS imaging and the moving target trajectory forming with raw SAR/GMTI Data

DBS (Doppler beam sharpening) technique is widely used in military. In this paper, the basic theory of DBS imaging is introduced at first, and a conclusion is reached by analysis that range cell migration correction technique and azimuth dechirping technique can improve image quality effectively on SAR/GMTI (synthetic aperture radar/ground moving target indication) mode. And it is possible to form the moving target trajectory on the image because of the high resolution. Lastly, some satisfactory results based on the raw radar data are presented

Optimal kernel design and time-frequency analysis for frequency hopping signal using entropy measure

In this paper we have proposed an optimal procedure of bi-directional Gaussian kernel based on third order entropy measure with volume normalized and applied to estimate hop timing, hopping frequency and hop during of FH signals embedded in additive white Gaussian noise. The estimation performance has been evaluated by comparison with signal-dependent radially Gaussian kernel. Simulation results have shown that the proposed method presents modest improvements in the threshold SNR and estimation variances over the latter.

An improved asynchronous pipeline architecture for real-time video decoder implementation

Asynchronous pipeline structure is adopted for the real-time video decoder design because of its better performance when the stage processing times are irregular. However, the structure requires a lot of memories, the invaluable resource on chip, to buffer data and parameters between modules. To solve this problem, a specially designed switching buffer module is used between stages instead of traditional FIFO, and the module can also take some buffering function in each stage, which helps to reduce the utilization of memory. An H.264 decoder with the proposed structure was implemented. Compared to decoder without improved structure, the experimental decoder can save nearly 50% memory and 31% I/O operations between stages.

Temporal spreading effect of oceanic lidar system

In this paper, multipath temporal spreading distributions of laser pulses are calculated when they travel through the seawater. Individual photon is followed in Monte Carlo calculation. A modified Henyey-Greenstein (HG) function is applied to represent the scattering phase function of seawater. This paper proposes a new scaling method, which uses the effective scattering thickness τd to replace the optical thickness used in the traditional scaling technique. This paper compares the temporal spreading distributions of photons of conditions of different attenuation coefficients and target depths. The experiments reveal that these mutual deviations are changing in the range from 0.5% to 5%, so long as the corresponding effective scattering thicknesses τd remains the same. Therefore, a conclusion can be obtained, that the temporal spreading distribution is only dependent on the effective diffusion thickness τd.

An improved method of Doppler centroid estimation in SAR

Successful processing of Synthetic Aperture Radar (SAR) requires that the Doppler centroid frequency (f/sub dc/) be accurately estimated. The energy balancing method is one of the methods to estimate the f/sub dc/, though it has some shortcomings. The paper brings forward an improved method which estimates the f/sub dc/ more effectively. This paper finally shows the new methods results by processing raw data and analyzes its performance. A conclusion is drawn that the results of the improved method are precise; furthermore, the improved method can compute the f/sub dc/ without iterative computations, so it is more suitable for real time processing on DSP and has higher efficiency.

The improvement of the conventional GMTI method with single-channel SAR

SAR/GMTI (synthetic aperture radar/ground moving target indicator) can detect targets with low velocities and provide images of the area covered by a scanning antenna with high revisit rates. By the conventional GMTI method, the estimated velocity of the moving target is not accurate. The authors improve it by a new idea which uses a series of moving windows. This paper shows the new methods results by processing raw radar data and analyzes its performance finally. A conclusion is drawn that the improved method is more effective and accurate for GMTI.