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Abstract-This paper addresses the real-time demand of radix-4 FFT processor in modern digital signal processing domain. Full parallel and pipelined architecture can be a good solution while too much hardware is consumed. Therefore a useful optimization method of complex multiplier and twiddle factor which has been successfully used to implement the FFT algorithms achieving a reduction in multipliers'...
The distribution of pole-zero determines the property of the automatic control system. The paper studies how the additional zeros in the left half of the s-plane affect the transient performance specification of the system by Matlab tools and analyzes the essential reasons for these effects.
Spectrum sensing is a crucial issue in cognitive radio networks for primary user detection. Energy detection is widely makes the detector unreliable due to the varied noise power. In this paper, we take noise uncertainty into consideration for three kinds of hard fusion strategies (OR rule, AND rule, and Majority rule), and compare the sensing performance for these fusion rules to achieve the reliable...
This paper addresses the problem of the adaptable conditions for Gaussian approximated expressions of energy detection over AWGN and Rayleigh channels. Gaussian approximated expressions of false alarm and detection probabilities have been widely adopted for evaluating the sensing performance of energy detection when the number of samples is large. With deeper study, we find the fact is not such. Extensive...
This paper addresses the problem of the optimal fusion rule adopted in cooperative spectrum sensing over different channels. Evidence from the previous literatures suggests that OR rule is a good choice for cooperative spectrum sensing. After deeply research, we find the fact is not such. Extensive analysis and numerical simulations confirm that OR rule is a good choice in a few cases, such as Rayleigh...
In cognitive radio system, softened hard combination scheme with two-bit overhead for each cognitive radio (CR) user can achieves a good tradeoff between detection performance and complexity. In this paper, we study the performance of two-bit hard combination scheme and derive formulas of false alarm and detection probability under imperfect reporting channel. Also the comparison of performances between...
This paper addresses the problem of energy detection of a primary signal in a cognitive radio environment over Nakagami channels. As an extension to the previous works, we start with the no diversity case, and present some alternative closed-form expressions of detection probability under Nakagami channels. Then we pay much attention to studying the square-law combining technology when wireless users...
In cognitive radio networks, cooperative spectrum sensing is employed to detect the presence of primary user quickly. In this paper, we study the sensing performance of a cognitive user U1 by allowing another cognitive radio user U2 to act as its relay (cooperation). We take the average power rather than the instantaneous power as the decision statistic, so, we can use multiple signal samples in each...
In cognitive radio networks, cooperative spectrum sensing is employed to detect the presence of primary user quickly. In this paper, we study the improvement on sensing performance for a cognitive user U1 by allowing another cognitive radio user U2 to act as its relay, when there is transmit power constraint for the relay U2. We first propose a novel numerical model for sensing performance analysis,...
In cognitive networks, cooperative spectrum sensing is employed to detect the presence of primary user quickly. In this paper, we study the sensing performance of a cognitive user U1 by allowing another cognitive user U2 to act as its relay. We vary the scaling factors (used by the relay U2 to amplify its received signal) of the unconstrained scheme (there is not power constrain for relay), and develop...
In cognitive networks, cooperative spectrum sensing is employed to detect the presence of primary user quickly. The difference of sensing performance between totally cooperative networks and partially cooperative networks (network cooperation gain) is studied in this paper. In a two user partially cooperative network, cognitive users U1 and U2 share their sensing results. While in a totally cooperative...
In cognitive networks, cooperative spectrum sensing is employed to detect the presence of primary user quickly. In this paper, we study the improvement in sensing performance of a cognitive user U1 by allowing another cognitive user U2 to act as its relay. We derive the expression of SNR, and exploit the improvement in SNR to explain why the sensing performance may be improved by using cooperation...
In cognitive radio networks, cognitive users have to detect the presence of primary users. In this paper, we exhibit the improvement in the probability of detection of an user U1 by allowing other user U2 to act as a relay. Assuming that users experience Rayleigh fading, and the decision statistic is the instantaneous power, at the same time, there is no transmit power constraint to relay, we find...
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