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Master-Vortrag: Optimized Power Allocation on NOMA-based Overlay Cognitive Radio Networks
Freitag, 27. März 2020
Spectral efficiency (SE) is crucial for wireless networks due to the scarcity of wireless spectrum and the ever increasing number of users that need access to it. Cognitive radios (CRs) are a prominent solution for SE as they facilitate spectrum sharing between two or more users. Another technique for improving SE, which has recently come in to focus, is nonorthogonal multiple access (NOMA). Together, they have immense potential for enabling highly spectrally efficient communication. A type of NOMA called power domain nonorthogonal multiple access (PD-NOMA) has been considered in downlink for a CR network in this thesis. PD-NOMA is essentially a multiple access (MA) technique that multiplexes the signals for users in the power domain. Hence, the division of power among the user signals is a critical PD-NOMA process known as power allocation (PA).
In this thesis, two methods for PA have been proposed namely, k-scaled PA and fair PA. The performance of the users in the CR network for each of these methods has been extensively evaluated. It has been noted that k-scaled PA reduces the information overhead when there are a large number of users in the network. While it has also been observed to be robust against interference, k-scaled PA method does not always lead to optimum power division. Therefore, fair PA has been proposed for achieving similar performance at all the users. However, it is only applicable for users with specific channel conditions. Also, up to 5 users have been accommodated in the network using the k-scaled method, enabling communication over the same spectral resource.