Scheduling and Resource Allocation Strategy for OFDMA Systems Over Time-Varying Channels Muayad S. Al-Janabi • Charalampos C. Tsimenidis • Bayan S. Sharif • Ste ´phane Y. Le Goff Received: 12 January 2011 / Accepted: 15 June 2011 / Published online: 30 June 2011 Ó Springer Science+Business Media, LLC 2011 Abstract A cross-layer scheduling and resource alloca- tion (SRA) strategy for an adaptive modulation and coding (AMC) based orthogonal frequency multiple access (OF- DMA) system is proposed. The objective of this paper is to maximize the system throughput as a function of the bit error rate (BER) and the spectral efficiency based on the selected modulation and coding schemes (MCSs). The proposed strategy contains two main algorithms. Firstly, the scheduling algorithm that aims to maximize the average system throughput by arranging the users in distinct queues according to their priorities and selecting the best user of each queue individually in order to guarantee a fair user service amongst different priority levels. Secondly, the resource allocation algorithm that allocates the user, bit and power based on the channel conditions of the scheduling users and the transmission power constraints. The trans- mitter of the investigated AMC-OFDMA system at the assigned base station (BS) divides the transmitted OFDMA frame into sub-channels and assigns each sub-channel to a scheduled user. In this paper, we compare the performance of the proposed SRA with the conventional first in first out (FIFO) queuing based scheduling and resource allo- cation strategies used for an AMC-OFDMA system. The simulation results show that the investigated AMC-OF- DMA system based on the proposed SRA strategy out- performs the conventional approaches. Keywords Cross-layer criteria  User scheduling  Resource allocation  Throughput  AMC-OFDMA 1 Introduction Multi-carrier-multiple-access systems that work across open system interconnection (OSI) layers, such as orthog- onal frequency multiple access (OFDMA), have been adopted by most mobile networks to increase data rates and average system throughput. The OSI layers manage the information transmission between the assigned base station (BS) and mobile terminals, i.e. users utilize efficient pro- tocols. Moreover, each layer is designed to achieve a specific target, such as scheduling and resource allocation, using common optimization methods [1–8]. The Mobile WiMAX standard considers adaptive modulation and coding (AMC) techniques, which utilize different MCS options, as well as optimal resource allocation strategies to work in combination with OFDMA environments in order to exploit channel capacity efficiently [9–13]. Several scheduling and resource allocation strategies have been proposed in literature. In [1], an optimal scheduling and resource allocation strategy was proposed. In the resource allocation part of the strategy, the power and bit allocation algorithm was presented, but the user allocation algorithm was not considered. The authors of [10] proposed a cross-layer adaptive resource allocation and scheduling algorithm for a multiple input multiple output (MIMO) OFDM system. This algorithm considered the interaction of cross OSI layers for different protocols. M. S. Al-Janabi (&)  C. C. Tsimenidis  B. S. Sharif  S. Y. L. Goff Electrical, Electronics and Computer Engineering, Newcastle University, Merz Court, NE1 7RU Newcastle Upon Tyne, UK e-mail: m.s.c.al-janabi@ncl.ac.uk C. C. Tsimenidis e-mail: charalampos.tsimenidis@ncl.ac.uk B. S. Sharif e-mail: bayan.sharif@ncl.ac.uk S. Y. L. Goff e-mail: stephane.le-goff@ncl.ac.uk 123 Int J Wireless Inf Networks (2011) 18:119–130 DOI 10.1007/s10776-011-0158-9