Optimal Pilot-Based Channel Estimation in Cognitive Radio
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Optimal Pilot‑Based Channel Estimation in Cognitive Radio D. Raghunatharao1 · T. Jayachandra Prasad2 · M. N. Giri Prasad3
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Cognitive radio (CR) technology is to assure the better utilization of the spectrum, permitting the non-licensed users to utilize the unused bands provided to the Licensed or primary users, which is made effective through the application of the Orthogonal Frequency Division Multiplexing (OFDM). The effective utilization of the OFDM channels through temporarily allocating the bands to the unlicensed users avoids interference. In order to ensure the reliable spectrum sensing in CR with effective spectral efficiency, the channel estimation (CE) is enabled in the OFDM-based multi-input and multi-output systems. The channel estimation is facilitated through the pilot-based sequential approach for the least square CE in OFDM-based CR. The optimal insertion of the pilots in the input data symbols before transmitting the signal through the fading OFDM channels in CR is made through the proposed rider grey wolf optimization, which is the integration of the grey wolf optimization and rider optimization algorithm. The estimation is done through the least square of the original channel state and the estimated symbols. The experimental analysis is progressed both in Rician and Rayleigh environments with minimal mean square error of 1.28E−06 and bit error rate of 0.000626. Keywords Channel estimation · Pilot symbols · Cognitive radio · Optimization · Orthogonal frequency division multiplexing (OFDM)
* D. Raghunatharao [email protected] T. Jayachandra Prasad [email protected] M. N. Giri Prasad [email protected] 1
ECE Department, SVR Engineering College (Affiliated to Research Scholar, JNTUA, Anantapuramu), Nandyal, Andhra Pradesh, India
2
RGM College of Engineering and Technology (Autonomous), Nandyal, Andhra Pradesh, India
3
Department of ECE, JNTUA College of Engineering, Anantapuramu, Andhra Pradesh, India
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1 Introduction CR aims at enhancing the spectral efficiency through permitting the unlicensed secondaryusers (SUs) to use the service range of licensed primary-users (PUs) with the tolerable interference to PUs. Conventionally, the secondary network is a half-duplex (HD), where there is orthogonal transmission and reception with respect to time or frequency [1, 2]. An intelligent wireless system, CR is a smart radio device capable of adapting to the environment through modifying the communication parameters, which aims at two goals, high reliable communication and efficient utilization of the radio spectrum [3, 4]. In CR, secondary users use the licensed bands without interfering with the licensed users (LUs) [3, 5–7]. For acquiring this, there are three steps, like sensing, decision making, and making appropriate actions. There are two problems in modern wireless communication, like poor spectrum efficiency and demand for high radio spectrum, whi
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