Optimal Sensing and Interference Suppression in 5G Cognitive Radio Networks Gashema Gaspard and Dong-Seong Kim Dept. of IT Convergence Engineering, School of Electrons Engineering, Kumoh National Institute of Technology, Gumi, 39177, South Korea. Email: ggas05@kumoh.ac.kr; dskim@kumoh.ac.kr Abstract—This paper proposes a technique to enhance both throughput and sensing time in secondary network under Full- Duplex Cognitive Radio (FD-CR). Subsequently, it overcomes power-throughput trade-off which is caused by SI-interference occurs during transmission. To do so, the CR node controls its transmission power over two fractions of frame duration unlike Simultaneous Sensing and Transmission (SST) approach which consists of controlling the entire frame duration. The performance was validated through simulation result using MATLAB simulation environment, then compare these results with that of existing approach (i.e.; SST). It was shown that, the proposed technique significantly outperforms SST in terms of throughput and sensing efficiency. Index Terms—Cognitive radio networks, full-duplex, optimal sensing, power control, SI suppression I. INTRODUCTION Since last decade, wireless and mobile communications have globally dominated all communication systems. This growth was accelerated by the new services with emergent applications such as the introduction of industrial Internet of Things (iIoT), automotive industry (such as big data analysis, artificial intelligence, and three-dimensional media), coverage for crowded stadiums, and high-speed rails. Herein, the demand for communication has become higher. Therefore, the corresponding internet speed and bandwidth are needed to spur this new technology wave in order to connect a huge number of devices for efficient communication during data exchange. Many researchers have been making effort to tackle this problem by introducing and developing next generation technology of wireless communication known as 5G. This technology is expected to support a large number and a more diverse set of devices by effectively managing the current resources. Now, the current technical and environmental challenges are: Manuscript received August 1, 2019; revised March 2, 2020. This research was supported by the MSIT (Minister of Science, ICT), Korea, under the ITRC (Information Technology Research center) support program (IITR-2019-2014-00639) supervised by the IITP (Institute for Information and Communication Technology Planning & Evaluation). Corresponding author email: dskim@kumoh.ac.kr. doi:10.12720/jcm.15.4.303-308 1. How to design mobile radio networks to be more energy efficiency and to accommodate the extra traffic while maintaining the quality of service. 2. How to increase the capacity of radio spectrum with the limited radio resources. To overcome these challenges, the spectrum sharing schemes have been proposed to offer efficient communication services to address the current requirements. Over the last two decades, cognitive radio (CR) technology was revealed as the most auspicious technology to be used in spectrum sharing to tackle the above-mentioned problem of underutilization of the spectrum. It (CR) was initially conceived and defined by Mitola [1] as an intelligent, adaptive, radio and network technology employed in wireless communication system to automatically sense the usage of surrounding spectrum; and opportunistically uses the spectral holes without affecting licensed users’ normal communication [2]. This consists of how a secondary (cognitive) network can efficiently exploit the primary network by accessi ng incumbent licensed frequency bands based on an opportunistic approach in CR technology. For efficient communication, the level of spectrum utilization should be significant enough to satisfy the communication needs among users in their communication environment. However, the required time for secondary users (SUs) to detect the unused spectrum is a critical issue, especially when a large number of users is trying to access the available channels. In essence, cognitive users have to sense primary users (PUs)’ spectrum as quick as possible to decrease the error rate in detection. In another words, sensing time is of utmost importance during spectrum sharing. The SUs must sense the status of the primary network to ensure the protection of its Quality of Service (QoS). The concept of traditional detection [3] proved that increasing sensing times allows decreasing the probability of false alarms, which leads to the protection of PUs from harmful interference. However, this increment in sensing time increases data transmission time, hence reduction of the achievable throughput of SUs. This mechanism is referred to as the sensing- throughput trade-off in CR networks; and the main Journal of Communications Vol. 15, No. 4, April 2020 ©2020 Journal of Communications 303