Access to RF White Spaces in Romania: Present and Future

Marțian, Alexandru; Crăciunescu, Răzvan; Vulpe, Alexandru; Suciu, George

doi:10.1007/s11277-015-2638-1

Cited by 10 publications

(5 citation statements)

References 20 publications

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“…Considering the transmission of the video stream under the harsh communication conditions in the deep space a BSS (Bundle Streaming Service) protocol [11] is proposed. In addition, there are many related works in the fields of Ad-Hoc Networks [12] and 5G [13,14].…”

Section: Related Work 21 Research Work On Space Networkmentioning

confidence: 99%

A Realistic, Flexible and Extendible Network Emulation Platform for Space Networks

Hou

Zhao

et al. 2022

Electronics

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Wide attention has been drawn to the application of space networks (SN) in recent years. Compared with terrestrial networks, SN have a set of unique characteristics, e.g., a long propagation delay, time-varying channel quality, and dynamic link connection, which causes the inapplicability of mature terrestrial networking technologies. Therefore, the focus of SN application is to innovate and break through a series of key networking technologies and protocols. Network emulation is critical for evaluation and verification in the research of networking technologies and protocols. This paper concentrates on designing an emulation platform which provides a realistic, flexible, and extensible experimental environment for the SN. The architecture of platform includes four components, namely the logical plane, control plane, data plane and measurement plane. Container technology is adopted to flexibly symbolize network nodes. The emulation method of dynamic connection relationships and time-varying link characteristics between pairwise nodes are considered so as to realize the real space environment and arbitrary topology. Furthermore, an extensible structure is described to emulate large-scale scenarios and access external emulation resources. Finally, experiment results show that the proposed platform is capable of emulating diverse, dynamic, and complex SN scenarios with high precision.

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Section: Related Work 21 Research Work On Space Networkmentioning

confidence: 99%

A Realistic, Flexible and Extendible Network Emulation Platform for Space Networks

Hou

Zhao

et al. 2022

Electronics

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“…We have to note that the initialization of Newton's iterative method, used to solve the optimization equation from (21), and its convergence are strongly related to the convexity of the DEP function. According to the DEP function's convexity demonstrated in Theorem 1, we know that the best initialization values of λ should be the values of the inflection points, i.e., either λ (1) in f lec or λ (2) in f lec given in (14). However, for the analytical derivation of the optimum value of λ, the use of λ (1) in f lec or λ (2) in f lec in the expressions of the optimization function from (21) and its derivative function would have complex expressions.…”

Section: Numerical Approach To Finding the Optimal 3eed Sensing Thresholdmentioning

confidence: 99%

“…According to the DEP function's convexity demonstrated in Theorem 1, we know that the best initialization values of λ should be the values of the inflection points, i.e., either λ (1) in f lec or λ (2) in f lec given in (14). However, for the analytical derivation of the optimum value of λ, the use of λ (1) in f lec or λ (2) in f lec in the expressions of the optimization function from (21) and its derivative function would have complex expressions. Instead, we prefer to use the values of λ for which the argument variables a and b in the optimization Equation (21) take null values, i.e., a = 0 or b = 0.…”

Section: Numerical Approach To Finding the Optimal 3eed Sensing Thresholdmentioning

confidence: 99%

“…The expansion of wireless communication systems in all sectors of modern society over the past decade has prompted an increased demand in spectrum resources. In this context, the traditional static allocation of the radio frequencies leads to inefficient use of the spectrum [1,2], and cognitive radio (CR) systems have emerged as a meaningful alternative for improving the efficiency of spectrum usage through dynamic spectrum access (DSA) [3]. DSA allows the access of secondary users (SU) to licensed frequency bands when these are not actively used by licensed primary users (PU), and relies on spectrum sensing, which is performed by the SU to detect the presence of active PU.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Three-Event Energy Detection with Adaptive Threshold for Spectrum Sensing in Cognitive Radio Systems

Marțian

Sammarraie

Vlădeanu

et al. 2020

Sensors

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Implementation of dynamic spectrum access (DSA) in cognitive radio (CR) systems requires the unlicensed secondary users (SU) to implement spectrum sensing to monitor the activity of the licensed primary users (PU). Energy detection (ED) is one of the most widely used methods for spectrum sensing in CR systems, and in this paper we present a novel ED algorithm with an adaptive sensing threshold. The three-event ED (3EED) algorithm for spectrum sensing is considered for which an accurate approximation of the optimal decision threshold that minimizes the decision error probability (DEP) is found using Newton’s method with forced convergence in one iteration. The proposed algorithm is analyzed and illustrated with numerical results obtained from simulations that closely match the theoretical results and show that it outperforms the conventional ED (CED) algorithm for spectrum sensing.

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“…Sub-Nyquist sampling technology [1,2,3,4,5,6,7], in which the sampling frequency is smaller than the Nyquist sampling rate [8], was proposed because there is redundancy in any information [9]. This technology can be applied in various fields, e.g., wireless communication [10] and synthetic aperture radar (SAR) [11,12,13,14,15,16,17]. Synthetic aperture radar takes samples of signals reflected from an illuminated scenario/scene to obtain a high-resolution image after processing at all times and in all weather conditions [18,19].…”

Section: Introductionmentioning

confidence: 99%

Sub-Nyquist SAR Based on Pseudo-Random Time-Space Modulation

Chen

et al. 2018

Sensors

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Sub-Nyquist sampling technology can ease the conflict between high resolution and wide swath in a synthetic aperture radar (SAR) system. However, the existing sub-Nyquist SAR imposes a constraint on the type of the observed scene and can only reconstruct the scene with small sparsity (i.e., number of significant coefficients). The information channel model of microwave imaging radar based on information theory, in which scene, echo, and the mapping relation between the two correspond to information source, sink, and channel, is built, and noisy-channel coding theorem explains the reason for the aforementioned under this model. To allow the wider application of sub-Nyquist SAR, this paper proposes sub-Nyquist SAR based on pseudo-random space-time modulation. This modulation is the spatial and temporal phase modulation to the traditional SAR raw data and can increase the mutual information of information source and sink so that the scenes with large sparsity can be reconstructed. Simulations of scenes with different sparsity, e.g., an ocean with several ships and urban scenes, were run to verify the validity of our proposed method, and the results show that the scenes with large sparsity can be successfully reconstructed.

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Access to RF White Spaces in Romania: Present and Future

Cited by 10 publications

References 20 publications

A Realistic, Flexible and Extendible Network Emulation Platform for Space Networks

A Realistic, Flexible and Extendible Network Emulation Platform for Space Networks

Three-Event Energy Detection with Adaptive Threshold for Spectrum Sensing in Cognitive Radio Systems

Sub-Nyquist SAR Based on Pseudo-Random Time-Space Modulation

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