Rank-Based Secrecy Rate Improvement Using NOMA for Ultra Dense Network

Non-orthogonal multiple access (NOMA) has emerged as an integral component for the future cellular networks. The purpose to install more small cells in the vicinity of a macrocell is to provide seamless and ubiquitous coverage to a huge density of users. Hence, security becomes an important aspect, which needs to resolve for users under critically acclaimed applications. The conventional encryption techniques and physical layer security measures may not be feasible always in Ultra Dense Network due to limited resources. Thus, the NOMA-based multiple access (MA) technique is emphasized to ensure reliability and confidentiality to users under dense picocells deployment. This paper sheds light on the security challenges of vehicular users and examines the impact of the NOMA-based MA technique on overall performance in comparison to the conventional approach. We design a training model to determine the density of vehicular users in a given picocell, before assigning power and resources. However, the proposed approach takes care of low mobile vehicular users as the eavesdropper tends to impact them more. The operation of NOMA-enabled users under the influence of intracellular and intercellular interference is also discussed. The results demonstrate that NOMA is successful in achieving a high sum rate for vehicular users by efficiently exploiting the resources in the power domain. To end this, we also compare the NOMA-based solution for the same scenario with the conventional approaches.