Due to the rapidly increasing energy consumption of the wireless communication systems, designing an energy-efficient system has become an important challenge. One can consider cooperative communication as a promising solution to reduce energy consumed by wireless networks. Hence, in this paper, we study the problem of maximizing energy efficiency by optimally allocating power in three cooperative channel scenarios. Unlike the previous works, imperfect channel state information is considered for all channels. Therefore, energy efficiency functions are derived considering channel estimation errors, and the following optimization problems are formulated to maximize the energy efficiency under the maximum transmission power and the minimum spectral efficiency constraints. Regarding the energy efficiency function behavior, an alternating optimization algorithm is used to find pilot and data transmission power at the source node. It also optimizes the power amplification gain of pilot and data at the relay node. Simulation results demonstrate that the imperfect channel state information condition can degrade the energy efficiency performance significantly. However, using the proposed power allocation method can improve the performance and compensate for the negative effect of channel estimation error. Moreover, the effect of circuit power on the optimal energy efficiency is investigated. It is shown that for a lower range of spectral efficiency, the negative effect of circuit power is greater than the channel estimation error’s negative effect, while for the higher values, the estimation error dominates the circuit power. We also observe that the results obtained from the proposed power allocation algorithms are close to the results of the global search method.

由于无线通信系统的能耗迅速增加，设计节能系统已成为一项重要的挑战。可以将协作通信视为减少无线网络消耗的能量的有前途的解决方案。因此，在本文中，我们研究了在三个协作信道方案中通过优化分配功率来最大化能源效率的问题。与先前的工作不同，所有通道都考虑了不完善的通道状态信息。因此，在考虑信道估计误差的情况下导出了能效函数，并提出了以下优化问题，以在最大发射功率和最小频谱效率约束下最大化能效。关于能效功能行为，交替优化算法用于查找源节点处的导频和数据传输功率。它还优化了中继节点处导频和数据的功率放大增益。仿真结果表明，不完善的信道状态信息条件会大大降低能效性能。然而，使用所提出的功率分配方法可以改善性能并补偿信道估计误差的负面影响。此外，研究了电路功率对最佳能量效率的影响。结果表明，对于较低的频谱效率范围，电路功率的负面影响大于信道估计误差的负面影响，而对于较高的值，估计误差将主导电路功率。