INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS Int. J. Commun. Syst. 2014; 00:1–26 Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/dac QoS-Aware Energy-Efficient Resource Allocation in OFDM-Based Heterogenous Cellular Networks Li Zhou 1∗ , Chunsheng Zhu 2 , Rukhsana Ruby 2 , Xiaofei Wang 2 , Xiaoting Ji 3 , Shan Wang 14 , Jibo Wei 1 1 College of Electronic Science and Engineering, National University of Defense Technology, Changsha, China 2 Department of Electrical and Computer Engineering, The University of British Columbia, Vancouver, BC, Canada 3 College of Mechatronic Engineering and Automation, National University of Defense Technology, Changsha, China 4 Science and Technology on Information Transmission and Dissemination in Communication Networks Laboratory, Shijiazhuang, China SUMMARY Recently, in order to satisfy the heavy demands of network capacity brought about by the proliferation of wireless devices, service providers are increasingly deploying heterogeneous cellular networks (HetNets) for boosting the network coverage and capacity. In this paper, we present an iterative energy-efficient scheduling scheme (IEESS) for downlink OFDM-based HetNets with quality-of-service (QoS) consideration. We formulate the problem as a nonlinear fractional programming problem aiming to maximize the QoS-aware energy efficiency (QEE) in HetNets. In order to solve this problem, we first transform it into a parametric programming problem, which takes QEE as an evolved parameter in the iterative procedure of IEESS. In each iteration, for the given value of QEE, subchannel and power assignment sub-problem is a nonlinear NP-hard problem. And hence we adopt dual decomposition method for obtaining the optimal assignment of subchannels and power of the sub-problem for the given value of QEE. Simulation results depict that both outer QEE parameter search and inner subgradient search can converge in a few iterations and the resultant solutions outperform the equal power allocation scheme (EPAS) [1] and capacity maximization scheme (CMS) [2] in terms of QEE. Copyright c ⃝ 2014 John Wiley & Sons, Ltd. Received . . . KEY WORDS: QoS-aware; Energy Efficiency; Resource Allocation; Heterogenous Networks * Correspondence to: College of Electronic Science and Engineering, National University of Defense Technology, Changsha, China. E-mail: zhouli2035@nudt.edu.cn Copyright c ⃝ 2014 John Wiley & Sons, Ltd. Prepared using dacauth.cls [Version: 2010/03/27 v2.00]