Abstract
Recently, researchers pay much attention to Wireless Power Transfer-supported Device-to-Device (D2D) Communication underlaying Cellular Network (WPT-DCCN), which has reliable and controllable energy resource, high energy and spectral efficiency. However, the Energy Efficiency (EE) of the whole WPT-DCCN, which combines the time allocation and the power control of all users (including base station, cellular and D2D user), is rarely studied. Consequently, this study establishes an EE optimization model of the whole WPT-DCCN. Facing the complexity of the modeled mathematical model, the EE problem is approximately converted to a convex one by a proposed Convex Approximation Scheme (CAS). Due to the fractional expression of the variables needed to be solved, it is hard to directly obtain an optimal solution for the converted convex problem through current convex optimization toolbox such as CVX. Thus, we skillfully utilize the Generalized Benders Decomposition (GBD) to obtain an optimal solution for the converted convex problem by analyzing the characteristics of the converted problem. Simulation results show that the proposed CAS can give a tight lower-bound solution of the original EE problem. Furthermore, CAS can help us to investigate some meaningful system features, for example the suitable energy conversion efficiency setting under different WPT-DCCN scenarios, which can give us a clear reference about the deployment of future WPT-DCCN.
Highlights
The ever increasing mobile devices bring tremendous pressures in aspects of massive data transmission demand, huge energy consumption and spectrum access requirement for future cellular network
Facing so complicated mathematical model, this study comes up with a successful Convex Approximation Scheme (CAS) which can obtain a tight lower bound of the original EE problem
There is a big time allocation gap between CAS and Violence Searching Method (VSM), a valid conclusion can be drawn from the small difference in EE performance: the proposed algorithm CAS can obtain a tight lower bound of the problem PEE by comparing with the optimal performance obtained by VSM with a lower computational complexity; 2) As illustrated by Figure 4, under the same condition of η, the needed time for Wireless Power Transfer (WPT) (τ ) keeps going up as D2D user (DU) moves away from Base Station (BS) because more time resources will be consumed as the distance increases to support the transmission requirement of DUs
Summary
The ever increasing mobile devices bring tremendous pressures in aspects of massive data transmission demand, huge energy consumption and spectrum access requirement for future cellular network In this situation, the generation of mobile cellular network is expected to deal with all of these severe pressures at the same time, and achieve a more ’green’ and efficient communication network [1]. Considering the complexity of the system, some research works investigate the Coupled Time and Power resource Optimization Problem (CTPOP) under overlay mode [18], [19] and convert the non-convex CTPOP into a convex one by a perspective operation [19]. Facing the more complex mutual interference of the underlay mode, researchers aim to study the time allocation and power control of DU under the threshold constraint of transmission data of CU and the different network QoS.
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