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This paper investigates biases of a parametric estimator of Doppler shift in mobile communications, and the result indicates that the conventional iterative autocorrelation function (ACF) estimator yields a significant estimation error at high mobile speeds. Therefore, a simple linear fitting is proposed to refine the Doppler shift estimation, in which only one fitting expression is required for different...
This paper presents a joint estimator for Doppler shift and SNR in wireless communications, which is derived from the relation of level crossing rate (LCR) and signal-to-noise ratio (SNR) in mobile propagations. Computer simulations clearly show a good performance for our joint estimator in a wide range of SNRs and velocities.
With the increase in size and application are of the communication network, more attention has been paid to the invulnerability of mobile ad hoc network. By analyzing the working mechanism and key techniques of the Ad Hoc Qos routing models, the searching for the most optimal routing is NP-hard problem. There is only sub-optimal routing available because of the rather high complexity of the algorithm...
TD-SCDMA has begin its commercial process in many cities of China, and equipment manufacturers are in dire need of the cheaper and simpler test solutions. Hence this paper investigates the TD-SCDMA protocol and then designs a novel radio frequency (RF) signal generator (source) by combining the ADS software and the conventional RF generation hardware. The key of the proposed process is modeling &...
This paper presents a signal-to-noise ratio (SNR) insensitive Doppler shift estimator based on the square envelope autocorrelation function (SEACF) of mobile propagation channels, where an iterative processing is employed to eliminate the approximation error and the effects of additive noise. Both theory and simulation show a good SNR-insensitive performance in a wide range of velocities and SNRs.
A novel iterative Doppler shift estimator is proposed in this letter for the Doppler shift estimation in very low signal- noise-ratio (SNR) environment. The proposed method exploits the logarithm envelope (LE) of the mobile propagation channel, and iteratively finds the minimum mean square error (MMSE) estimation of the Doppler shift. Extensive simulation results conducted under a wide range of the...
Mobile ad hoc networks (MANET) have recently emerged as a hot research topic. To solve the expansibility problem of traditional flat routing protocols in ad hoc networks, a dynamic clustering routing transition protocol was proposed in this paper. This method creates clusters dynamic by real-time apperceiving network scale which can solve the conflict between the expansibility of flat routing protocols...
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