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Physical Layer Security in Non-Orthogonal Multiple Access (NOMA) Networks

Jahanbazi, Shahab | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51500 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Mirmohseni, Mahtab
  7. Abstract:
  8. The increasing expansion of wireless communications and the increase in information traffic and the number of communication users, and on the other hand, the frequency and energy frequency limitations have led to the emergence of new generation communications. In the fifth generation of communications, one of the solutions to ensure the optimal use of bandwidth is the use of the non-orthogonal multiple access (NOMA) schema, which of course, the use of such a scheme in the system naturally increases the complexity of the receivers. Unlike most access methods in previous generations of communications, the goal of NOMA is the simultaneous use of multiple users from a frequency band for data transmission. Also, since in NOMA systems, users with better channel status decode other users’ messages, it seems logical users to relay this decoded information to help users with a weaker channel status. For this purpose, one of the required power supply methods is to connect the battery to users with a strong channel status. Because of the openness of wireless communications, the issue of system security matters. It is also in NOMA scheme systems, given the importance of assigning the same resources to multiple users, this becomes even more important. In this thesis, two issues are generally discussed on the security of NOMA systems. In the first issue, the design of a secure schema in multi-input single-output NOMA systems, when there are legitimate users and a eavesdropper in the environment, for different modes, the feedback on the tune-up channel has been investigated. Also, for a second issue, the system model is intended to be the use of cooperative sending, that for simplicity, users are divided into two groups, which close users act as decoder and forward relays, and users are far away from eavesdropper. The goal is to maximize the total rate of poor users under the condition of system security. For such a multi-user model, the problem of optimal channel assignment and the allocation of power to users is considered to optimize the total rate of poor users. Due to the structure of NOMA, the general form of the problem of non-convex optimization is the result of which iterative algorithms are used to solve this problem
  9. Keywords:
  10. Physical Layer Security ; Non-Orthogonal Multiple Access ; Cooperative Multiple Access ; Physical Layer Security

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