Journal of Electronics (China)

Balance power control is based on the idea of balancing Carrier to Interference Ratio (CIR) of all wireless links. Unbalance power control means that different traffics can achieve different CIR at receivers. This paper proposes a forward link partial-balance power control algorithm, which can provide necessary Quality of Service (QoS) for multimedia traffics in Wideband CDMA(W-CDMA) systems. The proposed algorithm is the integration of grading traffics priority and allocating and adjusting forward link power levels. For higher priority traffics, the unbalance power control is used. Whereas for lower priority traffics, balance power control is adopted. Computer simulation results show that the proposed algorithm can guarantee the special QoS requirements of the traffics with higher priority orders and maximize the CIR of the traffics with lower priority orders.

This paper introduces the concept of the primary subgraph of a composite graph associated with a linear active network, and presents a new and efficient topological method, called the primary subgraph method, for linear active network analysis. This method is an improvement and unification of the complete tree method and directed tree method. It thoroughly solves the sign evaluation problem and cancellation term problem.

In CDMA mobile communication systems, multiple access interference can be canceled by multiuser detection technique. The Degradation by channel fading can be reduced by diversity reception. This paper investigates a family of multiuser receivers that combined decorrelating detection, antenna diversity and RAKE multipath diversity. The performance of the multiuser receivers is analyzed. The results demonstrate a significant increase in the performance of the receivers by using multiuser detection and diversity reception.

In wireless communication environment, the time-varying channel and angular spreads caused by multipath fading and the mobility of Mobile Stations (MS) degrade the performance of the conventional Direction-Of-Arrival (DOA) tracking algorithms. On the other hand, although the DOA estimation methods based on the Maximum Likelihood (ML) principle have higher resolution than the beamforming and the subspace based methods, prohibitively heavy computation limits their practical applications. This letter first proposes a new suboptimal DOA estimation algorithm that combines the advantages of the lower complexity of subspace algorithm and the high accuracy of ML based algorithms, and then proposes a Kalman filtering based tracking algorithm to model the dynamic property of directional changes for mobile terminals in such a way that the association between the estimates made at different time points is maintained. At each stage during tracking process, the current suboptimal estimates of DOA are treated as measurements, predicted and updated via a Kalman state equation, hence adaptive tracking of moving MS can be carried out without the need to perform unduly heavy computations. Computer simulation results show that this proposed algorithm has better performance of DOA estimation and tracking of MS than the conventional ML or subspace based algorithms in terms of accuracy and robustness.

The microwave back-scattering characteristics are numerically analysed by the electromagnetic scattering theory, and the sea wave height spectrum that reflects the wind field is rebuilt by comparing the calculated data with experimental data which were measured by airborne scatter. According to the wave height spectrum, the relationship between the back-scattering coefficients and wind speeds can be obtained. Once the back-scattering coefficients of the sea surface are measured, then the wind speeds over the sea surface can approximately be determined. It is useful for the microwave remote sensing in ocean.

This paper presents a new solution to the image segmentation problem, which is based on fuzzy-neural-network hybrid system (FNNHS). This approach can use the experiential knowledge and the ability of neural networks which learn knowledge from the examples, to obtain the well performed fuzzy rules. Furthermore this fuzzy inference system is completed by neural network structure which can work in parallel. The segmentation process consists of pre-segmentation based on region growing algorithm and region merging based on FNNHS. The experimental results on the complicated image manifest the utility of this method.

In 1982, Fu presented his work on realizing Maxwell’s demon. Fu declared that a perpetual current was obtained in his device. This means that a new machine of the second kind of perpetual motion has been invented. In this paper, the author gives a detail analysis on Fu’s work, and the following conclusion has been obtained: (1) In Fu’s experiment, the object centrolled by the magnetic field was electrons in mass, not in individuality. The magnetic field did not separate electrons individually into a high-speed group nor a low-speed group. For this reason, it was not a “demon”. The whole process in the experiment was a mass-flowing process of an enormous amount of small particles. This must belong to the area of thermodynamics. (2). The current flowing in Fu’s device is actually the initial velocity current of a vacuum diode. (3) The initial velocity current is, in turn, a modified form of Thomson thermo-electric effect, which requires a hot tank and a cold tank, obeying the second law of thermodynamics. (4) The role of action of the magnetic field is to control electronsin mass, causing a waak rectification in the device. The current should vanish if there has no such action, because the initial velocity electrons should eliminate by each other. (5) Fu’s approach was not a proper approach to realize the Maxwell’s hypothesis.

Error propagation seriously degenerate the diversity order of Decode-and-Forward (DF) cooperative communication. To address this problem, a novel Log Likelihood Ratio (LLR)-based Link Adaptive Relaying (LAR) is proposed to promote adaption accuracy at relay. The instantaneous Bit Error Probability (BEP) is calculated according to the LLR of the received signals firstly, then based on it, the equivalent Signal-to-Noise Ratio (SNR) is employed to operate dynamic power scaling by relay. It is theoretically proved that the full diversity order can be attained by the scheme. Besides, the power sensitivity is also analyzed. Simulation results show that the proposed scheme outperform the conventional LAR and can achieve full diversity order. Moreover, its strong adaptation to SNR fluctuation is validated.