H. Nikmanesh - Department of Computer Engineering, Eqbal Lahoori Institution, Mashhad, Iran,
A. Balali - Faculty of Electrical and Computer Engineering, Hakim Sabzevari University, sabzevar, Iran,

As the number of users and large-scale heterogeneous traffic increases, fifth generation (5G) wireless networks face various challenges; so security services and new multiple access (MA) schemes are being developed to meet changing needs.In this paper a promising technology called non-orthogonal multiple access (NOMA) that is capable of meeting some of the challenges for the 5G is discussed. Unlike conventional orthogonal multiple access (OMA) technologies, NOMA is capable of preparing more than one user through non-orthogonal source allocation. NOMA techniques include power-domain NOMA, code-domain NOMA, and NOMA multiplexing in multiple domains. The choice of appropriate modulation methods and multiple access to achieve efficient performance is very important. Furthermore, the 5G wireless network systems offer new security requirements. The security solutions base on the security services ( authentication, availability, confidentiality and integrity).In this paper, first compared NOMA techniques, and then a review of engineering requirements for a 5G system is presented. At the end, the attacks and security services are expressed.

5G, NOMA, Attacks, security.