This paper considers the power allocation problem in device-to-device (D2D) communication underlaying a cellular network and investigates the impact of different transmitting and interference power constraints on the energy efficiency and spectral efficiency of the network. We formulate the power allocation problem in D2D communication as a nonlinear fractional programming problem with an objective to maximize the energy efficiency of a D2D communication link subject to four different combinations of transmitting and interference power constraints. To solve the original formulated nonlinear fractional programming problem, we first convert it into a dual nonlinear parametric programming problem, and then decouple the dual problem into several solvable concave problems. Further, a closed-form solution is derived to each dual problem and an efficient power allocation algorithm is proposed to find a numerical solution to the formulated problem. Simulation results show that the proposed power allocation algorithm outperforms an ergodic capacity maximization algorithm and a uniform power distribution algorithm in terms of the energy efficiency of a D2D link, and can efficiently improve the overall ergodic capacity of a cellular network.

本文考虑了蜂窝网络下的设备到设备（D2D）通信中的功率分配问题，并研究了不同的发射功率和干扰功率约束对网络的能效和频谱效率的影响。我们将D2D通信中的功率分配问题表述为非线性分数规划问题，其目标是在发射和干扰功率约束的四种不同组合下，最大化D2D通信链路的能量效率。为了解决最初制定的非线性分数规划问题，我们首先将其转换为对偶非线性参数规划问题，然后将对偶问题解耦为多个可解决的凹问题。进一步，为每个对偶问题导出一个封闭形式的解决方案，并提出了一种有效的功率分配算法来找到所提出问题的数值解决方案。仿真结果表明，所提出的功率分配算法在D2D链路的能量效率方面优于遍历容量最大化算法和均匀功率分配算法，并且可以有效地提高蜂窝网络的遍历容量。