Abstract
The non-orthogonal multiple access (NOMA) schemes, where the users are allowed to share the same time-frequency resource, have recently received a major interest to meet the increasing demands for higher data rates, improved user fairness, and/or lower latency applications in future dense-user wireless networks. Moreover, the achievable user rates of NOMA schemes can be further increased through the integration of these multiple access schemes with other enabling schemes such as full-duplex user cooperative communications. In this paper, the optimization of the achievable max-min rates for full-duplex cooperative NOMA (CNOMA) schemes for the two-user scenario are re-visited and is extended to the three-user scenario where novel expressions for the optimal user cooperation power are derived for both scenarios. The obtained results shed new lights on the optimal transmit power allocation and the optimal user cooperation power allocation in CNOMA systems and the different design trade-offs in such systems.
Highlights
The increasing mobile data use and emerging new applications in fifth generation (5G) and beyond networks require peak data rates in the order of Gigabits per second with low latency
THE COOPERATIVE PD-non-orthogonal multiple access (NOMA) SYSTEM: TWO-USER CASE REVISITED A two-user cooperative NOMA scheme has a strong user (User 1) that is close to the base station (BS) or the access point (AP) with stronger channel gain and a second user (User 2) that is farther away from the BS/AP with weaker channel gain
The results are extensible to fading channels; that will require the derivations of the outage capacity, for a given QoS target rate, and ergodic capacity expressions which is beyond the scope of this paper
Summary
The increasing mobile data use and emerging new applications in fifth generation (5G) and beyond networks require peak data rates in the order of Gigabits per second with low latency This motivated the move from the current congested radio bands to higher frequency bands such as millimeter wave (mm-wave) band [1], THz, and even visible light communications (VLC) bands [2]. While the optimization of achievable sum rate of cooperative NOMA systems has been well-investigated as in [16] and references therein, only few works have considered the optimization of another common fairness measure which is the max-min achievable rates. The developed formulations are extensible to fading channels to derive the corresponding outage and ergodic capacity metrics
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