A novel centralized approach for Dynamic Spectrum Allocation (DSA) in the Cognitive Radio (CR) network is presented in this paper. Instead of giving the solution in terms of formulas modeling network environment such ...A novel centralized approach for Dynamic Spectrum Allocation (DSA) in the Cognitive Radio (CR) network is presented in this paper. Instead of giving the solution in terms of formulas modeling network environment such as linear programming or convex optimization, the new approach obtains the capability of iteratively on-line learning environment performance by using Reinforcement Learning (RL) algorithm after observing the variability and uncertainty of the heterogeneous wireless networks. Appropriate decision-making access actions can then be obtained by employing Fuzzy Inference System (FIS) which ensures the strategy being able to explore the possible status and exploit the experiences sufficiently. The new approach considers multi-objective such as spectrum efficiency and fairness between CR Access Points (AP) effectively. By interacting with the environment and accumulating comprehensive advantages, it can achieve the largest long-term reward expected on the desired objectives and implement the best action. Moreover, the present algorithm is relatively simple and does not require complex calculations. Simulation results show that the proposed approach can get better performance with respect to fixed frequency planning scheme or general dynamic spectrum allocation policy.展开更多
IS1921 VF-256 type ground object spectrometer was used to extract the spectral data of the meadow grassland and bare land to obtain their refleotivity spectral characteristics. The experiment was carried out on the lo...IS1921 VF-256 type ground object spectrometer was used to extract the spectral data of the meadow grassland and bare land to obtain their refleotivity spectral characteristics. The experiment was carried out on the low mountain meadow steppe in the Saiwundu Village, Hargentai Town, West Ujumqin Banner, Xilin Gol League, Inner Mongolia. The results showed that different ground objects had different reflectances. The spectral reflectance curve of the meadow steppe plant communities had obvious characteristics of peak and valley in the visible spectrum band, and had strong reflection in the near-infrared band. The reflection curve of the bare lands in the visible spectrum band was higher than that of the meadow grassland communities while inthe near-infrared band it was lower than that of the meadow grassland communities. Under different degradation gradients, the spectral reflectivity of the meadow steppe grassland communities increased with the enhancement of the degradation gradients. Under the same degradation gradient, the Stipa grandis communities had a lower visible light reflectivity than the Artemisia frigida communities but had a higher near-infrared reflectivity than the Artemisia frigida communities; different ground objects on the meadow steppe had different spectrum characteristic, and showed a certain discrepancies with the changes of the degradation level.展开更多
基金supported in part by National Science Fund for Distinguished Young Scholars project under Grant No.60725105National Basic Research Program of China (973 Pro-gram) under Grant No.2009CB320404+1 种基金National Natural Science Foundation of China under Grant No.61072068Fundamental Research Funds for the Central Universities under Grant No.JY10000901031
文摘A novel centralized approach for Dynamic Spectrum Allocation (DSA) in the Cognitive Radio (CR) network is presented in this paper. Instead of giving the solution in terms of formulas modeling network environment such as linear programming or convex optimization, the new approach obtains the capability of iteratively on-line learning environment performance by using Reinforcement Learning (RL) algorithm after observing the variability and uncertainty of the heterogeneous wireless networks. Appropriate decision-making access actions can then be obtained by employing Fuzzy Inference System (FIS) which ensures the strategy being able to explore the possible status and exploit the experiences sufficiently. The new approach considers multi-objective such as spectrum efficiency and fairness between CR Access Points (AP) effectively. By interacting with the environment and accumulating comprehensive advantages, it can achieve the largest long-term reward expected on the desired objectives and implement the best action. Moreover, the present algorithm is relatively simple and does not require complex calculations. Simulation results show that the proposed approach can get better performance with respect to fixed frequency planning scheme or general dynamic spectrum allocation policy.
基金Supported by Inner Mongolia Meteorological Brueau Technology ResearchProject(200618)~~
文摘IS1921 VF-256 type ground object spectrometer was used to extract the spectral data of the meadow grassland and bare land to obtain their refleotivity spectral characteristics. The experiment was carried out on the low mountain meadow steppe in the Saiwundu Village, Hargentai Town, West Ujumqin Banner, Xilin Gol League, Inner Mongolia. The results showed that different ground objects had different reflectances. The spectral reflectance curve of the meadow steppe plant communities had obvious characteristics of peak and valley in the visible spectrum band, and had strong reflection in the near-infrared band. The reflection curve of the bare lands in the visible spectrum band was higher than that of the meadow grassland communities while inthe near-infrared band it was lower than that of the meadow grassland communities. Under different degradation gradients, the spectral reflectivity of the meadow steppe grassland communities increased with the enhancement of the degradation gradients. Under the same degradation gradient, the Stipa grandis communities had a lower visible light reflectivity than the Artemisia frigida communities but had a higher near-infrared reflectivity than the Artemisia frigida communities; different ground objects on the meadow steppe had different spectrum characteristic, and showed a certain discrepancies with the changes of the degradation level.
