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 Dynamic spectrum access with deep Q-learning in densely occupied and partially observable environments

2021 ◽  
Vol 13 (1) ◽  
pp. 1-6
Author(s):  
Slavica Tomović ◽  
Igor Radusinović
Keyword(s):  
Dynamic Spectrum Access ◽  
Simulation Analysis ◽  
Dynamic Spectrum ◽  
Spectrum Access ◽  
Channel State ◽  
Q Learning ◽  
Communication Environments ◽  
Markov Decision ◽  
History Of ◽  
Partially Observable

In this paper, we propose a new Dynamic Spectrum Access (DSA) method for multi-channel wireless networks. We assume that DSA nodes do not have prior knowledge of the system dynamics, and have only partial observability of the channels. Thus, the problem is formulated as a Partially Observable Markov Decision Process (POMDP) with exponential time complexity. We have developed a novel Deep Reinforcement Learning (DRL) based DSA method which combines a double deep Q-learning architecture with a recurrent neural network and takes advantage of a prioritized experience buffer. The simulation analysis shows that the proposed method accurately predicts a channel state based on the fixed-length history of partial observations. Compared with other DRL methods for DSA, the proposed solution can find a near-optimal policy in a smaller number of iterations and suits a wider range of communication environments, including dynamic ones, where channel occupancy pattern changes over time. The performance improvement increases with the number of channels and with a channel state transition uncertainty. To boost the performance of the algorithm in densely occupied environments, multiple DRL exploration strategies are examined and evaluation results are presented in the paper.

Demand-Oriented Optimal Spectrum Sensing Order in Dynamic Spectrum Access

2014 ◽  
Vol 543-547 ◽  
pp. 2262-2265
Author(s):  
Chang Hua Yao ◽  
Qi Hui Wu ◽  
Xue Qiang Zheng
Keyword(s):  
Cognitive Radio ◽  
Spectrum Sensing ◽  
Dynamic Spectrum Access ◽  
Radio Networks ◽  
Dynamic Spectrum ◽  
Spectrum Access ◽  
Throughput Performance ◽  
Order Problem ◽  
Data Packets ◽  
Definition Of

In this paper, we proposed a more practical spectrum sensing order problem in cognitive radio networks (CRN), considering the effect of different traffic of second user (SU). We discard the impractical assumption that SU has data packets to transmit all the time, and use the actually packets per second rather than the channel capacity as the definition of throughput, to reformulate the optimal sensing order problem. The new method to decide sensing order can improve the throughput performance in practical system.

“Threshold-Deciding” Policy in Distributed Multiuser Opportunistic Spectrum Access

2014 ◽  
Vol 926-930 ◽  
pp. 2867-2870
Author(s):  
Yu Meng Wang ◽  
Liang Shen ◽  
Xiang Gao ◽  
Cheng Long Xu ◽  
Xiao Ya Li ◽  
...  
Keyword(s):  
Opportunistic Spectrum Access ◽  
Spectrum Access ◽  
Secondary Users ◽  
Adaptive Policy ◽  
Markov Decision ◽  
Single User ◽  
Simulation Results ◽  
Partially Observable ◽  
Time And Energy ◽  
The Given

This paper studies the problem of distributed multiuser Opportunistic Spectrum Access based on Partially Observable Markov Decision Process (POMDP). Due to the similarity of spectrum environment, secondary users may choose the same channel adopting their own single user approach, which leads to collision. Referring to the previous works, we propose a more flexible and adaptive policy named “threshold-deciding”. Firstly, the SU gets a channel by adopting the random policy. Secondly, the SU decides whether to sense the channel by comparing the available probability with the given threshold. The policy not only decreases the collisions among SUs but also reduces the consumption of time and energy. The simulation results shows that the upgrade of performance is up to 100% compared with the existing random policy, which demonstrate the advantage of the proposed policy.

scholarly journals The SS-SCR Scheme for Dynamic Spectrum Access

2012 ◽  
Vol 2012 ◽  
pp. 1-12
Author(s):  
Vinay Thumar ◽  
Taskeen Nadkar ◽  
U. B. Desai ◽  
S. N. Merchant
Keyword(s):  
Dynamic Spectrum Access ◽  
Optimization Problem ◽  
Activity Patterns ◽  
Cooperative Relaying ◽  
Dynamic Spectrum ◽  
Cross Layer ◽  
Spectrum Access ◽  
Cross Layer Optimization ◽  
Simulation Results ◽  
Symbiotic Cooperative Relaying

We integrate the two models ofCognitive Radio (CR), namely, the conventionalSense-and-Scavenge (SS) Model and Symbiotic Cooperative Relaying (SCR). The resultant scheme, calledSS-SCR, improves the efficiency of spectrum usage and reliability of the transmission links.SS-SCRis enabled by a suitable cross-layer optimization problem in a multihop multichannel CR network. Its performance is compared for different PU activity patterns with those schemes which considerSSandSCRseparately and perform disjoint resource allocation. Simulation results depict the effectiveness of the proposedSS-SCRscheme. We also indicate the usefulness of cloud computing for a practical deployment of the scheme.

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.

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