Abstract
The fifth generation (5G) wireless communication systems promise to provide massive connectivity over the limited available spectrum. Various new transmission paradigms such as non-orthogonal multiple access (NOMA) and cognitive radio (CR) have emerged as potential 5G enabling technologies. These techniques offer high spectral efficiency by allowing multiple users to communicate on the same frequency channel, simultaneously. A combination of both techniques may further enhance the performance of the system. This work aims to maximize the achievable rate of a multi-user multi-channel NOMA based CR system. We propose an efficient user pairing, channel assignment and power optimization technique for the secondary users while the performance of primary users is guaranteed through interference temperature limits. The results show that, at small values of the power budget or high interference threshold, optimizing channel allocation and user pairing proves to be more beneficial than optimal power allocation to the user pairs. The proposed joint optimization technique provides promising results for all values of the power budget, interference threshold and rate requirement of the communicating users.
Highlights
Orthogonal multiple access (OMA) techniques have proven their efficiency in the fourth generation (4G) of communication systems [1,2]
In a practical scenario, it becomes more beneficial to consider a combination of non-orthogonal multiple access (NOMA) and OMA where the available spectrum is divided into multiple channels and each channel is shared by multiple users in a NOMA fashion
We considered the problem of maximizing the sum rate of the secondary users in a NOMA based cognitive radio (CR) system
Summary
Orthogonal multiple access (OMA) techniques have proven their efficiency in the fourth generation (4G) of communication systems [1,2]. The power domain NOMA is considered to be the backbone of the 5G communication networks because of least computational complexity and excellent performance. In NOMA, the signals of different users are transmitted simultaneously on the same channel with different power levels. In NOMA, each channel is shared by multiple users. The spectrum efficiency of NOMA systems is very high [9]. In multi user NOMA systems the complexity and delay because of SIC increases rapidly with the number of users sharing a channel. In a practical scenario, it becomes more beneficial to consider a combination of NOMA and OMA where the available spectrum is divided into multiple channels and each channel is shared by multiple users in a NOMA fashion.
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