Research Article Dynamic Fractional Frequency Reuse Diversity Design for Intercell Interference Mitigation in Nonorthogonal Multiple Access Multicellular Networks Kashif Mehmood , 1 Muhammad Tabish Niaz, 2 and Hyung Seok Kim 1 1 Department of Information and Communication Engineering, Sejong University, Seoul, Republic of Korea 2 Smart Device Engineering, Sejong University, Seoul, Republic of Korea Correspondence should be addressed to Hyung Seok Kim; hyungkim@sejong.edu Received 16 March 2018; Revised 7 June 2018; Accepted 25 June 2018; Published 15 July 2018 Academic Editor: Kostas Peppas Copyright © 2018 Kashif Mehmood et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Nonorthogonal multiple access (NOMA) is one of the few promising techniques that can ensure the achievement of benefts foreseen in next-generation 5G wireless networks and beyond. By using superposition coding, NOMA allows multiple users to share the same time and frequency resources, thereby enhancing user connectivity, spectral efciency, and a considerable increase in user throughput. Interference mitigation is an important consideration in NOMA and is considerably more infuencing in multicellular environments. First, a brief description of the impairments that can arise in a NOMA cellular network along with responsible factors is provided. Second, diferent approaches adopted to minimize these impairments are discussed. Finally, a possible solution is proposed that consists of a coordinated approach between the individual cells in the NOMA domain to minimize interferences and improve user throughput. Adaptive fractional frequency reuse (FFR) is used to allocate distinct frequency resources to edge users of diferent cells to minimize intercell interference in NOMA. Simulation results prove that the proposed NOMA scheme plays an important role in minimizing impairment efects and enhancing the SINR and the throughput performance of edge users while ensuring fairness in its design. 1. Introduction Wireless cellular networks have seen unprecedented growth in the last decade in terms of increasing demand for user data rates as well as massive connectivity for users. Multimedia applications and services have seen a gradual and expected increase, leading to the design of specifc standards with a focus on seamless and smooth user experience. Next- generation wireless networks, including Long-Term Evolu- tion (LTE & LTE-A) were designed considering the growing user capacity needs and efcient use of the available spectrum to accommodate these users. LTE only ofers a couple of fold improvement in user capacity over third-generation (3G) networks and will be insufcient, considering the expected growth. Orthogonal multiple access (OMA) has been used widely in current and previous generations of wireless cellular networks for user access. Frequency resources are allocated in a disjoint manner to minimize interuser interference, thereby maximizing user throughput and connectivity up to a certain limit as allowed by the availability of frequency resources. Multiple OMA techniques currently being used include frequency-division multiple access (FDMA), time- division multiple access (TDMA), code-division multiple access (CDMA), and orthogonal frequency-division multiple access (OFDM). One of the most important and challenging criterion for next-generation (5G) cellular networks is for them to be able to provide user throughput 1000× more than that of current 4G network deployments. To fulfll these requirements, nonorthogonal multiple access (NOMA) with a successive interference cancellation (SIC) receiver was presented as one of the several promising candidate radio access techniques for future cellular networks. OMA users are separated based on a resource division mechanism, whereas a resource sharing approach is adopted for NOMA schemes. Resource sharing Hindawi Wireless Communications and Mobile Computing Volume 2018, Article ID 1231047, 18 pages https://doi.org/10.1155/2018/1231047