Abstract
In this paper, we consider a massive MIMO-enabled multi-way amplify-and-forward relay network with channel aging, where multiple users mutually exchange information via an intermediate relay equipped with massive antennas. For this system, we propose an energy-efficient power allocation scheme for the optimization of energy efficiency (EE). Specifically, we firstly derive accurate closed-form expressions of the system sum rate with aged channel state information (CSI) and predicted CSI. Secondly, based on the derived analytical results, a unified power allocation optimization problem with aged/predicted CSI is formulated for maximizing the system EE. To solve this challenging problem, the successive convex approximation technique is invoked to transform the original optimization problem into a tractable concave fractional programming problem. Then, Dinkelbach’s algorithm and Lagrangian dual method are adopted to find the optimal solution. In addition, to strike a balance between the computational complexity and the optimality, the EE maximization problem using the equal power allocation scheme is solved by extreme value theorem, leading to a closed-form optimal solution. Numerical results demonstrate the accuracy of our analytical results and the effectiveness of the proposed algorithms. Moreover, the impact of several important system parameters on the system performance achieved by the proposed algorithms is also illustrated.
Highlights
With the unprecedented growth of mobile data traffic volumes, the carbon emission of information and communication technologies is becoming an increasingly serious problem
As compared to one-way relay networks (OWRNs) and two-way relay networks (TWRNs), Multi-way relay network (MWRN) are capable of achieving higher capacity and spectral efficiency (SE) and can be employed to effectively deal with the ever increasing
Π j is the permutation matrix employed at the relay in the jth time slot of the broadcast phase, which is designed to ensure that the kth (k ∈ {1, · · ·, K}) User equipment (UE), receives the signal from the k th UE, with k = modK (k + j)
Summary
With the unprecedented growth of mobile data traffic volumes, the carbon emission of information and communication technologies is becoming an increasingly serious problem. It was shown in [7] that massive MIMO systems As another promising approach, multi-way relay networks (MWRNs) have recently received plenty of research interest [13, 14]. To the best of the authors’s knowledge, there is a paucity of contributions on energy-efficient transmission strategies of massive MIMO-enabled MWRNS, considering the effect of channel aging. Motivated by the above discussions, in this paper, we investigate low-complexity energy-efficient power allocation strategies for a massive MIMO-enabled MWRN with channel aging. We respectively derive closed-form expression of the achievable sum rate (SR) for aged and predicted CSI, which enables us to efficiently evaluate the system performance, facilitating the energy-efficient power allocation strategies. 2 Method This paper studies the energy-efficient power allocation problem of massive MIMO-enabled multi-way relay systems, under channel aging.
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