Abstract
In this paper, the resource allocation problem for user pairing (UP) in downlink non-orthogonal multiple access (NOMA) systems is investigated. NOMA allows the use of one subcarrier for more than one user at the same time, thus increases the total capacity of the wireless communication system. However, users pairing is a challenging task in the NOMA systems, because a good channel quality subcarrier should be selected and allocated for the user to enhance the performance of NOMA systems. The proposed UP algorithm aims to enhance the sum rate of the paired users per subcarrier and consequently enhance the total sum rate of downlink NOMA systems. Moreover, the proposed UP algorithm target to improve the fairness of the users. The proposed UP algorithm is based on a simple search for the subcarrier with the minimum average channel gains to be assigned its paired users and then excluding it from the next searching process. The proposed scheme ensures the higher channel gain for users by giving the priority to the subcarrier with the minimum average channel gains during the user pairing process. The simulation results demonstrate that the proposed UP algorithm can not only enhance the total sum rate compared with the random UP and conventional UP but also can enhance the fairness of the users. Moreover, it is clearly seen that the proposed UP algorithm provides the lowest outage probability.
Highlights
The ongoing exciting development of smartphones and tablets has led these devices to play a crucial role in our daily lives
The results show a remarkable hike in spectral and energy efficiency compared with conventional (CoMP-orthogonal multiple access (OMA)) networks
A fixed power allocation (PA) is considered to allocate the power to each subcarrier s between its two paired users, 0.2Ps is assigned to a strong user and 0.8 Ps is allotted to a weak user, where Ps is the power per subcarrier
Summary
The ongoing exciting development of smartphones and tablets has led these devices to play a crucial role in our daily lives. Applications like watching the television, playing online video games, and taking part in online classes can be executed effectively through our smartphones These increments in remote gadgets coupled with a fast insurgency in mixed media applications are changing the nature of wireless communication activity by increasingly requesting high data rates. Spectral inefficiency will occur, and it would be impossible to endorse large-scale networking and IoT, both of which have been considered as the main features of 5G networks [4] To overcome this limitation, NTT DoCoMo researchers innovated a new multiple access technique which is called non-orthogonal multiple access (NOMA), for the generation (5G) mobile network [5]. NOMA allows multiple users with diverse channel conditions to share the same subcarrier, resulting in significant spectral efficiency improvements.
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