Influence of Density on Throughput Performance in Cognitive Ultra-dense Networks


  • Antoni Ivanov Faculty of Telecommunications, Technical University of Sofia, bul. Kl. Ohridski 8, Sofia 1000, Bulgaria
  • Krasimir Tonchev Faculty of Telecommunications, Technical University of Sofia, bul. Kl. Ohridski 8, Sofia 1000, Bulgaria
  • Pavlina Koleva Faculty of Telecommunications, Technical University of Sofia, bul. Kl. Ohridski 8, Sofia 1000, Bulgaria
  • Vladimir Poulkov Faculty of Telecommunications, Technical University of Sofia, bul. Kl. Ohridski 8, Sofia 1000, Bulgaria



5G, densification, cognitive radio, energy detection, network coexistence, spectrum sharing, ultra-dense networks


Current advancements of Fifth Generation (5G) of mobile communications and beyond, have envisioned future networks as highly dense and coexisting in various bandwidths, providing seamless connectivity to users at any location. Thus, it is important to describe the effects and limits of densification and spectrum sharing. This article examines a less explored system model of a terrestrial cognitive radio (CR) based ultra-dense network (UDN) that operates within the range of a cellular macro base station (BS) and its users. It shares the incumbent spectrum in the interweave mode to avoid interference to the primary network, by implementing two common methods for energy detection (ED) spectrum sharing – Gaussian ED and Fading ED (FED). Through extensive simulations, the critical density of the UDN’s cognitive access points (CAPs), the ED efficiency, as well as the throughput gains, are determined through the measured signal-to-noise-ratio (SNR) at the CAPs and SUs. Additionally, the influence of different SU densification on the throughput is analyzed for the critical CAP density. It has been assessed that due to the high path loss in UDNs, the spectrum utilization gain (SUG) is small, but it may be improved through appropriate SU densification.


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Author Biographies

Antoni Ivanov, Faculty of Telecommunications, Technical University of Sofia, bul. Kl. Ohridski 8, Sofia 1000, Bulgaria

Antoni Ivanov received the PhD degree in Communication Networks and Systems from the Technical University of Sofia (TUS), Bulgaria. He holds a Master degree in Innovative Communication Technologies and Entrepreneurship from TUS, and Aalborg University, Denmark in 2016. He is currently a Postdoctoral researcher at the “Teleinfrastructure Lab”, Faculty of Telecommunications, TUS. His research interests include cognitive radio networks, adaptive algorithms for dynamic spectrum access, deep learning-based solutions for cognitive radio applications, volumetric spectrum occupancy assessment, and graph signal processing for resource allocation in current and future wireless networks.

Krasimir Tonchev, Faculty of Telecommunications, Technical University of Sofia, bul. Kl. Ohridski 8, Sofia 1000, Bulgaria

Krasimir Tonchev is a senior researcher leading the research activities at the “Teleinfrastructure Lab”, Faculty of Telecommunications, Technical University of Sofia, Sofia, Bulgaria. His research interests include Model Based Machine Learning, Bayesian data analysis and modelling, Neural Networks with applicatoins in Computer Vision and data analysis. He has also implemented many commercial projects including photogrammetry, object detecion and tracking using thermal vision, dynamic system modeling and image processing for embedded systems.

Pavlina Koleva, Faculty of Telecommunications, Technical University of Sofia, bul. Kl. Ohridski 8, Sofia 1000, Bulgaria

Pavlina Koleva received her M.Sc. and Ph.D. degrees in Telecommunications from the Technical University of Sofia, Bulgaria, in 2001 and 2013, respectively. Currently she is Associate Professor at the Faculty of Telecommunications. She has more than 15 years of teaching and research experience in the field of telecommunications. She has been involved in numerous projects, related to software design, development and support of various types of communication and data processing systems. Her main research interests are in Information Theory, Communication Networks, Game Theory, Cognitive networks, and Next Generation Networks, Big Data.

Vladimir Poulkov, Faculty of Telecommunications, Technical University of Sofia, bul. Kl. Ohridski 8, Sofia 1000, Bulgaria

Vladimir Poulkov has received the M.Sc. and Ph.D. degrees from the Technical University of Sofia (TUS), Sofia, Bulgaria. He has more than 30 years of teaching, research, and industrial experience in the field of Telecommunications. He has successfully managed numerous industrial, engineering, R&D and educational projects. He has been Dean of the Faculty of the Telecommunications at TUS and Vice Chairman of the General Assembly of the European Telecommunications Standardization Institute (ETSI). Currently the Head of the “Teleinfrastructure” R&D Laboratory at TUS and Chairman of Cluster for Digital Transformation and Innovation, Bulgaria. He is Fellow of the European Alliance for Innovation; Senior IEEE Member. He has authored many scientific publications and is tutoring BSc, MSc, and PhD courses in the field of Information Transmission Theory and Wireless Access Networks.


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