Energy Consumption Control in Cooperative and Non-Cooperative Cognitive Radio using Variable Spectrum Sensing Sampling

In cognitive radio (CR) network, the concept of energy-efficient design is very important considering the costly energy consumption that may limit its implementation, especially in battery-powered devices. In these networks, significant part of the energy is consumed in the energy detector during spectrum sensing to detect the presence and absence of the primary user (PU). In this paper, we investigated the reduction of energy consumption in two scenarios: the non-cooperative scenario and the cooperative scenario by reducing the number of sensed samples. We also explained the optimisation criteria for improving energy consumption by controlling the number of sensed samples, and the detection probability in both scenarios. The performance of energy detection system was evaluated in AWGN and Rayleigh fading channels. The simulation results show that in non-cooperative scenario at Eb/No of 10 dB, 50% and 46% of the energy consumed in the detection was saved when the number of sensed samples was reduced by 50% with acceptable loss in detection probability of 5% and 12% in AWGN and Rayleigh channel respectively. In cooperative scenario, the result shows that increasing the number of cognitive users (CU) reduced the average energy consumption per sensor and improved the detection probability

Generalized β\beta-conformal change and special Finsler spaces

In this paper, we investigate the change of Finslr metrics $$L(x,y) \to\bar{L}(x,y) = f(e^{\sigma(x)}L(x,y),\beta(x,y)),$$ which we refer to as a generalized $\beta$-conformal change. Under this change, we study some special Finsler spaces, namely, quasi C-reducible, semi C-reducible, C-reducible, $C_2$-like, $S_3$-like and $S_4$-like Finsler spaces. We also obtain the transformation of the T-tensor under this change and study some interesting special cases. We then impose a certain condition on the generalized $\beta$-conformal change, which we call the b-condition, and investigate the geometric consequences of such condition. Finally, we give the conditions under which a generalized $\beta$-conformal change is projective and generalize some known results in the literature.Comment: References added, some modifications are performed, LateX file, 24 page

Concurrent π\pi-vector fields and energy beta-change

The present paper deals with an \emph{intrinsic} investigation of the notion of a concurrent $\pi$-vector field on the pullback bundle of a Finsler manifold $(M,L)$. The effect of the existence of a concurrent $\pi$-vector field on some important special Finsler spaces is studied. An intrinsic investigation of a particular $\beta$-change, namely the energy $\beta$-change ($\widetilde{L}^{2}(x,y)=L^{2}(x,y)+ B^{2}(x,y) with \ B:=g(\bar{\zeta},\bar{\eta})$;$\bar{\zeta} $being a concurrent$\pi$-vector field), is established. The relation between the two Barthel connections$\Gamma$and$\widetilde{\Gamma}$, corresponding to this change, is found. This relation, together with the fact that the Cartan and the Barthel connections have the same horizontal and vertical projectors, enable us to study the energy$\beta$-change of the fundamental linear connection in Finsler geometry: the Cartan connection, the Berwald connection, the Chern connection and the Hashiguchi connection. Moreover, the change of their curvature tensors is concluded. It should be pointed out that the present work is formulated in a prospective modern coordinate-free form.Comment: 27 pages, LaTex file, Some typographical errors corrected, Some formulas simpifie

COMPLEXITY REDUCTION OF CYCLOSTATIONARY SENSING TECHNIQUE USING IMPROVED HYBRID SENSING METHOD

In cognitive radio system, the spectrum sensing has a major challenge in needing a sensing method, which has a high detection capability with reduced complexity. In this paper, a low-cost hybrid spectrum sensing method with an optimized detection performance based on energy and cyclostationary detectors is proposed. The method is designed such that at high signal-to-noise ratio SNR values, energy detector is used alone to perform the detection. At low SNR values, cyclostationary detector with reduced complexity may be employed to support the accurate detection. The complexity reduction is done in two ways: through reducing the number of sensing samples used in the autocorrelation process in the time domain and through using the Sliding Discrete Fourier Transform (SDFT) instead of the Fast Fourier Transform (FFT). To evaluate the performance, two versions of the proposed hybrid method are implemented, one with the FFT and the other with the SDFT. The proposed method is simulated for cooperative and non-cooperative scenarios and investigated under a multipath fading channel. Obtained results are evaluated by comparing them with other methods including: cyclostationary feature detection (CFD), energy detector and traditional hybrid. The simulation results show that the proposed method with the FFT and the SDFT successfully reduced the complexity by 20% and 40% respectively, when 60 sensing samples are used with an acceptable degradation in the detection performance. For instance, when Eb/N0 is 0 dB , the probability of the detection of Pd is decreased by 20 % and 10% by the proposed method with the FFT and the SDFT respectively, as compared with the hybrid method existing in the literature

Implementation of Selected Spectrum Sensing Systems for Cognitive Radio Networks using FPGA Platform, Journal of Telecommunications and Information Technology, 2018, nr 4

The energy efficient spectrum sensing method is very important in cognitive radio (CR), since high power drain may limit its implementation in mobile applications. The spectrum sensing feature consumes more energy than other functional blocks, as it depends on continuous detection of the presence or absence of the primary user (PU). In this paper, we proposed two methods to reduce energy consumption of the spectrum sensing feature. The first is of a single stage variety with a reduced number of sensed samples. The other uses two stages. The first stage performs coarse sensing for many subchannels, and the best subchannel is forwarded for fine sensing in the second stage. The performance of the proposed methods is evaluated in AWGN channel and compared with the existing approach. The proposed methods are simulated using Matlab and ModelSim and are then hardware implemented using the Altera Cyclone II FPGA board. Simulation results show that the proposed methods offer an improvement in energy consumption with an acceptable reduction in the probability of detection. At Eb/N0 Eb/N0 Eb/N0 of 0 dB, the energy consumption is reduced by 50% and 72% in the first and second proposed method, respectively, compared to the traditional method (100% sensing)

Nonlinear optical properties of selected natural pigments extracted from spinach: Carotenoids

They are report here, for the first time in authors knowledge, results on third order nonlinear optical susceptibilities from a series of natural pigments extracted from spinach. The measurements were performed in-situ at 532 nm wavelength using degenerate four wave mixing technique (DFWM). For comparison third order nonlinear optical susceptibilities of the same pigments were also evaluated using third harmonic generation (THG) set up at 1064 nm. The electronic contribution to the observed properties was also deduced. The measurements were performed on thin films deposited on a thick glass substrate. These pigments were also identified by UV–VIS spectral analysis. All these results were in good agreement with the literature data

Teaching in the light of mathematical proficiency competencies and its impact on achievement and mathematical self-concept of 8th grade Omani students

هدفت الدراسة إلى تعرّف أثر التدريس في ضوء كفايات البراعة الرياضية وأثره في التحصيل وفي مفهوم الذات الرياضي لدى طلبة الصف الثامن. وللتحقق من ذلك أعدَّ دليل للمعلم في وحدة الدوال والمعادلات في ضوء كفايات البراعة الرياضية. وتمّ إعداد اختبار للتحصيل الدراسي، وقياس الصدق والثبات له على عينة استطلاعية. وتشكّلت عينة الدراسة من (58) طالبًا من طلاب الصف الثامن الأساسي بمحافظة جنوب الباطنة في سلطنة عُمان، ووزّعت في مجموعتين إحداهما تجريبية، درست وحدة الدوال والمعادلات في ضوء كفايات البراعة الرياضية، والأخرى هي المجموعة الضابطة، ودرست الوحدة نفسها بالطريقة المعتادة. وقد توصلت الدراسة إلى وجود فرق ذي دلالة إحصائية عند مستوى الدلالة (0.05=α) بين متوسطي درجات طلبة المجموعة التجريبية ودرجات طلبة المجموعة الضابطة في التطبيق البعدي لاختبار التحصيل الدراسي لصالح متوسط درجات المجموعة التجريبية. ودلت النتائج على وجود فرق ذي دلالة إحصائية عند مستوى الدلالة (0.05=α) بين متوسطي درجات طلبة المجموعة الضابطة ودرجات طلبة المجموعة التجريبية في تطبيق مقياس مفهوم الذات الرياضي بعديًّا، وذلك لصالح متوسط درجات المجموعة التجريبية. وفيما توصلت إليه الدراسة من نتائج، فقد أوصت بتوظيف استخدام التدريس في ضوء كفايات البراعة الرياضية في تدريس موضوعات أخرى.