Abstract
We consider a robust design problem for achieving max-min fairness amongst users in an uplink non-orthogonal multiple access system under imperfect channel state information. Contrary to the conventional approach adopted in the literature, we propose an optimal decoding order-based successive interference cancellation technique by introducing new binary variables, which results in a difficult class of mixed-integer nonconvex optimization problem. For a practical application, we devise an efficient suboptimal solution based on the inner convex approximation framework, which solves a second-order-cone program at each iteration. Simulation results are provided to demonstrate its performance gain over state-of-the-art designs. The proposed design also yields data rates close to those obtained by an exhaustive search method.
Highlights
Power domain non-orthogonal multiple access (NOMA) has recently been recognized as a promising solution for generation of mobile communications, due to its capability of delivering higher throughput, improved reliability and increased spectral efficiency [1,2]
In downlink NOMA systems, successive interference cancellation (SIC) technique should be performed at users who have high processing power, especially in the case that the number of users in one resource block is large
Since the objective is monotonic in its argument, we focus on convexifying the nonconvex constraints in Equations
Summary
Power domain non-orthogonal multiple access (NOMA) has recently been recognized as a promising solution for generation of mobile communications, due to its capability of delivering higher throughput, improved reliability and increased spectral efficiency [1,2]. Contrary to the well-known water-filling method, NOMA aims at concurrently allocating different power levels to the users over the same spectrum. NOMA tends to allocate more power to the users with poorer channel conditions to guarantee the user fairness, while users in better channel conditions benefit from canceling the strong interference by using a successive interference cancellation (SIC) technique [3]. In downlink NOMA systems, SIC technique should be performed at users who have high processing power, especially in the case that the number of users in one resource block is large. A popular technique used in downlink NOMA systems is either to pair two users or to group a few users into one cluster with distinct channel conditions
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