中文摘要：

为了解决中继网络中基于能量效率的用户接入问题,将用户数据需求严格受限下基于能量效率最优的动态用户接入问题建模为一个整数优化问题,该问题类似于一个NP-hard的多维背包问题.首先,采用穷搜法分析了该问题最优解的复杂度.然后,提出了一种低复杂度、高效的基于能量效率的动态用户接入算法（UAEEM）.该算法在保证用户数据需求严格受限的前提下,按照系统射频端和电路端的能量效率最大原则,动态调整用户归属和中继的工作状态,以实现网络能量效率最大化.最后,通过仿真实验验证所提算法性能.结果表明,UAEEM算法能显著提高系统的能量效率、降低系统的计算复杂度,且其性能接近最优解.

英文摘要：

To solve the problem of user association based on energy efficiency in relay networks,the dynamic user association problem w ith energy efficiency maximization in w hich the rate requirements of all users are strictly guaranteed is formulated as an integer optimization problem.This problem is similar to a NP（non-deterministic polynomial）-hard multidimensional knapsack problem.First,the exhaustive search（ES） method is adopted to analyze the complexity of optimal solution.Then,a low complexity and effective algorithm,UAEEM（user association for energy efficiency maximization）,is proposed.In this algorithm,w ith the rate requirements of all users strictly guaranteed,the user’s serving station and operative mode of relays are dynamically altered according to the maximization of both the radio frequency energy efficiency and circuit energy efficiency;and thus,the total energy efficiency of the netw ork is maximized.Finally,the performance of the proposed algorithm is evaluated via simulation.Results show that the proposed UAEEM algorithm can significantly improve the netw ork energy efficiency and reduce the complexity,and it almost achieves the optimal solution.