scholarly journals Economy of Spectrum Access in Time Varying Multichannel Networks

2010 ◽  
Vol 9 (10) ◽  
pp. 1361-1376 ◽  
Author(s):  
M.H.R. Khouzani ◽  
Saswati Sarkar
Keyword(s):  
Time Varying ◽  
Spectrum Access ◽  
Multichannel Networks

Dynamic Spectrum Access Considering Channel Fading in Cognitive Networks

2014 ◽  
Vol 543-547 ◽  
pp. 2013-2016
Author(s):  
Ye Bin Tao ◽  
Shi Ding Zhu
Keyword(s):  
Dynamic Spectrum Access ◽  
Cognitive Networks ◽  
Dynamic Spectrum ◽  
Time Varying ◽  
Channel Fading ◽  
Spectrum Access ◽  
Throughput Performance ◽  
Markov Decision ◽  
Simulation Results ◽  
Partially Observable

This paper investigated the method of Dynamic Spectrum Access (DSA) in cognitive networks, considering the PU channels both time-varying and fading. We used the Partially Observable Markov Decision Process (POMDP) framework to model this problem and designed a greedy strategy. The simulation results shows that the proposed strategy obtained better throughput performance than the existing works.

scholarly journals Design of Wavelet-Encoded Symbol Constellations for Cyclostationary Spectrum Sensing

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Pedro Thiago Valério de Souza ◽  
Vinícius Samuel Valério de Souza ◽  
Luiz Felipe de Queiroz Silveira
Keyword(s):  
Cognitive Radio ◽  
Communication Systems ◽  
Dynamic Spectrum Access ◽  
Dynamic Spectrum ◽  
Optimization Approach ◽  
Time Varying ◽  
Spectrum Access ◽  
Wavelet Coding ◽  
Cognitive Radio Systems ◽  
Radio Systems

In mobile communication systems, the signals propagate through multipath over time-varying channels, which are subject to distortion caused by fading and Doppler shifts. In order to minimize such distortions, coding techniques and transmission diversity can be employed, e.g., wavelet coding. In this work, the wavelet coding is investigated in scenarios of cognitive radio systems with dynamic spectrum access. Cognitive radio systems with dynamic spectrum access should be able to sense unoccupied frequency bands for opportunistic transmissions, as well as detect the presence of primary users when they occupy their licensed spectrum. Therefore, an essential element for the accurate operation of cognitive radio systems encoded by wavelet coding is the ability to sense the signals encoded by this technique. It is effectively demonstrated that the possibility of sensing such signals is associated with a suitable design of the signal constellation used in the modulation of the coded symbols. The constellation design of these is performed via genetic algorithms using a multiobjective optimization approach. The developed system is evaluated according to the robustness to time-varying flat fading through a bit error probability (BER) versus Eb/N0 analysis. The spectral sensing ability is also addressed employing the cyclostationary analysis. The results denote the feasibility of using wavelet coding in radio scenarios with dynamic spectrum access, with good performance in terms of BER and signal detection rates.

Time-varying Macroeconomic Risk of Real Estate Returns

2016 ◽  
Author(s):  
Felix Schindler ◽  
Bertram Steininger ◽  
Tim Kroencke
Keyword(s):  
Real Estate ◽  
Time Varying ◽  
Macroeconomic Risk ◽  
Real Estate Returns
Sign in / Sign up

Export Citation Format

Share Document