1,720,992 research outputs found
Velocity Estimation in Cellular Systems Based on the Time-Frequency Characteristics of the Received Signal
No full textMobile velocity estimation for wireless communications
No full textIn this chapter we explain the principles of velocity estimation and review both analytically and using simulations the properties of existing estimators. We then discuss the importance of accurate velocity estimation in the context of handover algorithm design.We show how an error in velocity estimation can significantly increase the probability of dropped calls, leading to a poorer quality of service of the system. Some velocity estimators require prior estimation of the Rician factor. This chapter also presents two Rice factor estimators that have been shown to have better performance than existing estimator
Instantaneous Frequency Estimation of Frequency Modulated Signals in the Presence of Multiplicative and Additive Noise: Application to Mobile Communication Systems
No full textPublication in the conference proceedings of EUSIPCO, Toulouse, France, 200
Estimating the Instantaneous Frequency of Time-varying Mono-component Signals in a Mobile Communication Environment
No full textInstantaneous Frequency Estimation in the Presence of Complex Multiplicative and Additive Noise: Application to Jammer Excision in Wireless Environments
No full textRicean K-factor estimation in mobile communication systems
No full textWe propose an estimator for the Ricean K-factor which has applications in mobile communication systems. The estimator is based on the statistics of the instantaneous frequency (IF) of the received signal. Using simulations, we show that the proposed estimator is robust to shadowing and its mean-square error (MSE) is significantly lower than that of the envelope-based estimators
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Estimation of the velocity of mobile units in micro-cellular systems using the instantaneous frequency of the received signals
No full textHandover processes in micro-cellular systems are more involved than in cellular systems. In particular, micro-cellular systems suffer from the so-called corner effect where line-of-sight between the mobile station and the base station is suddenly lost when the mobile rounds a corner. As a result, the received signal drops rapidly below threshold level and the call can be lost. It has been shown that, if an accurate estimation of the velocity of the mobile unit is available, the call can be rescued by applying short temporal window averaging on the received signal. Current methods for estimating the velocity of mobile units in micro-cellular systems are based on the level crossing rate of the envelope of the received signals. This paper presents a new velocity estimator based on the instantaneous frequency of the received signal. The performance of the proposed estimator is shown to be superior to that of the level crossing rate method. The average relative error of the proposed estimator is down to below 8% whereas that of the LCR method reaches 14%
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