Lossless compression for spaceborne magnetic data is significant, especially for small, low-cost satellites or deep space exploration spacecrafts. However, most of existing lossless compression algorithms are difficul...
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The technology of chirp spread spectrum (CSS) has been around for decades, widely used in the fields of radar and sonar. In recent years, CSS has been used in the IEEE 802.15.4a and Long Range (LoRa) Internet of Thing...
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The technology of chirp spread spectrum (CSS) has been around for decades, widely used in the fields of radar and sonar. In recent years, CSS has been used in the IEEE 802.15.4a and Long Range (LoRa) Internet of Things (IoT), called LoRa modulation. On the other hand, CSS has never been used in low-Earth-orbit (LEO) satellite communication systems for low-data-rate transmission. CSS applied in LoRa as a kind of successful commercial IoT technology will promote research on its application in satellite communication for IoT. Recently, new types of chirp signals with the same chirp rate have become available to realize multiple accesses. This letter examines those types of chirp signal and the revised SCS called Asymmetry Chirp Signal (ACS) is proposed for better performance in LEO satellite IoT.
In this letter, we use squared iterative method with parameter checking to accelerate the convergence rate of expectation/conditional maximization (ECM) algorithm when estimating the channel parameters blindly in flat...
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In this letter, we use squared iterative method with parameter checking to accelerate the convergence rate of expectation/conditional maximization (ECM) algorithm when estimating the channel parameters blindly in flat fading nonGaussian channels, and further, we proposed automatic modulation classification (AMC) in flat fading non-Gaussian channels based on the proposed maximum likelihood estimator. The numerical results show that the proposed method can accelerate the convergence rate of ECM algorithm, and AMC based on the proposed method is faster than that based on ECM, while the accuracy of the former shows nearly no loss compared with that of the latter.
In this letter, we consider blind estimation of channel parameters over a frequency-selective channel. We use a blocked Rhee-Glynn smoothing estimator to derive E-step in the expectation-maximization (EM) algorithm. T...
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In this letter, we consider blind estimation of channel parameters over a frequency-selective channel. We use a blocked Rhee-Glynn smoothing estimator to derive E-step in the expectation-maximization (EM) algorithm. The proposed algorithm copes with the curse of dimensionality of a forward- backward algorithm;meanwhile, it is easy to parallelize, which is amenable to a modern computing hardware and speeds up the estimation of channel parameters. The experiment results show that the proposed algorithm is close to the Baum-Welch algorithm in terms of convergence of channel coefficients and outperforms the EM algorithm coupled with a joined two-filter smoothing algorithm in terms of convergence of channel coefficients and running time.
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