INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS Int. J. Commun. Syst. (2016) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/dac.3137 Joint scheduling and mapping in support of downlink fairness and spectral efficiency in ieee 802.16e OFDMA system Nguyen Huu Thanh 1, * ,† , Doan Van Tung 1 , Ngo Quynh Thu 1 , Nguyen Canh Nam 1 and Kumbesan Sandrasegaran 2 1 Hanoi University of Science and Technology, Hanoi, Vietnam 2 University of Technology Sydney, Sydney, Australia SUMMARY The next generation broadband wireless networks deploy orthogonal frequency division multiple access (OFDMA) as the enabling technologies for broadband data transmission with QoS capabilities. In such broadband wireless systems, one major issue is how to utilize radio resource efficiently while maintaining fairness between sessions as well as providing adequate QoS. In this work, we propose an approach for OFDMA/time division duplex (TDD) downlink suitable for IEEE802.16e WiMAX systems that combines scheduling and burst mapping algorithms for a trade-off between session fairness, QoS, and spectral effi- ciency. While optimizing radio resources under QoS and fairness constraints is an NP-hard problem, we follow a heuristic approach that simplifies the complexity of the algorithm. Performance results show that while the new scheme outperforms the Proportional Fair algorithm in terms of fairness, it also improves the overall system spectral efficiency. Copyright © 2016 John Wiley & Sons, Ltd. Received 28 April 2015; Revised 14 March 2016; Accepted 15 March 2016 KEY WORDS: OFDMA; scheduling; mapping; radio resource management; fairness; spectral efficiency 1. INTRODUCTION Orthogonal frequency division multiple access (OFDMA) transmission scheme is becoming popu- lar as it is the key technology for the fourth generation (4G) broadband wireless networks such as WiMAX and has been standardized by the WiMAX forum. OFDM/OFDMA technologies can meet the demands for high data rates, can operate in fading channels, and support line and non-line-of- sight operations with multipath mitigation. In combination with Medium Access Control (MAC) layer mechanisms, it can meet specific QoS requirements of active sessions. OFDMA can be con- sidered as a joint Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) scheme, in which data can be transmitted in both time domain and frequency domain simultaneously. In the time domain, the channel is divided into OFDM symbols, while in frequency domain, data can be transmitted in multiple orthogonal sub-carriers. Thus, it provides possibilities to exploit diversity of a frequency selective fading channel as the number of sub-carriers and OFDM symbols allocated to a session can be dynamically and effectively reserved based on user’s actual needs as well as the channel condition. However, the price for the efficiency gained at the Physical Layer is the increasing complexity at the MAC layer and several following related issues. In wireline systems, the channel resources, such as time slots or channel frequency bandwidth, can be allocated proportionally to the requested user data rates because all user equipments (UEs) have the same channel condition. Contradictionally, performing bandwidth allocation while keeping fairness and QoS for users in wireless networks appears to be a much complexer task because of pathloss, user mobility, and channel fading. There are some requirements for the design of the wireless MAC layer: *Correspondence to: Nguyen Huu Thanh, School of Electronics and Telecommunications, Hanoi University of Science and Technology, Hanoi, Vietnam. † E-mail: thanh.nguyenhuu@set.hust.edu.vn Copyright © 2016 John Wiley & Sons, Ltd.