Int. J. Advanced Networking and Applications Volume: 12 Issue: 06 Pages: 4793-4799(2021) ISSN: 0975-0290 4793 Adaptive Resource Optimization for Cognitive Radio Networks Kayalvizhi E Department of Electronics Engineering, MIT Campus, Anna University, Chennai, India Email: kayalvizhi179@gmail.com Balamurugan Gopalakrishnan Department of Electronics Engineering, MIT Campus, Anna University, Chennai, India Email: balanmail12@gmail.com -------------------------------------------------------------------ABSTRACT--------------------------------------------------------------- In cognitive radio network, the spectrum sensing finds either the channel is occupied or idle, the problem is assigning the unused channels of the primary user (PU) to the secondary users in an efficient manner is most challenging issue. In this work, we investigates the above issue and proposed an adaptive resource allocation to the secondary users in terms of channel allocation and power allocation. The proposed work intelligently handles both frequency and space efficiently without affecting the quality of service (QoS) of the primary user. We considered both underlay and overlay spectrum access, based on that resource allocation is carried out in an efficient manner. The maximum transmitted data rate of the secondary user (SU) obtained is 225Kbps determined by using Shannon channel capacity theorem. The proposed work also shows the effectiveness of the simulation in terms of energy efficiency up to 8.25 x 10 5 bits/Joule. Keywords - Resource allocation, Cognitive radio, OFDM, data rate, energy efficiency. -------------------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: Jun 07, 2021 Date of Acceptance: Jun 25, 2021 -------------------------------------------------------------------------------------------------------------------------------------------------- I. INTRODUCTION Wireless communication on an open shared medium require wireless technologies to cooperate and share the spectrum in a non-interference manner [1]. Due to an enormous increase in wireless technology leads to huge demand in spectrum. To overcome this issue, cognitive radio (CR) provides solution to spectrum scarcity where the licensed primary users (PUs) will share the unused spectrum to secondary users (SUs). The cognitive radio operates at IEEE 802.22 standards under the regional area network. The spectrum range for cognitive radio is 54- 862MHZ. Cognitive radio networks (CRNs) utilize the unused licensed spectrum in radio environments to establish network communications. It enhances the utilization of available radio frequency spectrum and interference is minimized with other users. Generally, the allocated primary users (PUs) spectrum is underutilized both in terms of time and space. The FCC has reported the temporal and geographical utilization of spectrum ranges between 15% to 85% [2]. Reusing of fixed spectrum to unlicensed users are not allowed which leads to spectrum scarcity for wireless applications. Besides spectrum scarcity it can also be used for secured communication because CR search for unused spectrum and switches the channels like frequency hop spread spectrum[3-6]. Fig. 1 shows the basic cognitive cycle with four main functions: spectrum sensing, spectrum decision, spectrum sharing and spectrum mobility. The spectrum sensing is to discover the status of the spectrum by sensing the white space or unused spectrum by the primary users (PU). In spectrum decision, the primary user's unused and best available channels are selected and decision is made to allocate the unused channel to the secondary users. The spectrum sharing, coordinate to access the white space or unused spectrum with other users. Finally, in spectrum mobility, the secondary users (SUs) immediately evacuate the used primary channel when licensed user is detected in the network. Figure 1. Cognitive radio module [7] Traditionally, spectrum cannot be utilized by unlicensed users when the spectrum is not used by licensed users. The development of cognitive radio allows to utilize the spectrum effectively by unlicensed users by maintaining interference level minimum to the primary users (PU) [8]. Based on spectrum policies of primary system, the dynamic spectrum access can be broadly classified as overlay, underlay and hybrid spectrum access. In the overlay spectrum access, the SUs can access the channel only when PU is not utilizing the channel [9]. In underlay spectrum access, the SUs can share the spectrum along with the PU by transmitting below the interference temperature [10]. The management of interference