Cognitive radio-based framework and self-optimizing temporal-spectrum block scheduling for QoS provisioning in WiMAX Jinchang Lu ⇑ , Maode Ma School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore article info Article history: Received 4 October 2009 Received in revised form 12 October 2010 Accepted 11 December 2010 Available online 17 December 2010 Keywords: QoS Cognitive radio Autonomic computing Self-optimizing Scheduling Mapping OFDMA WiMAX abstract Cognitive radio (CR) is seen as a solution to the current low-usage of the radio spectrum and the problem of the fixed spectrum allocation. Quality of service (QoS) provisioning is an important issue in the deployment of broadband wireless access networks with real- time and non-real-time traffic integration in wireless spectrum. The connection-level and packet-level scheduling scheme is essential to guarantee the QoS requirements of different service classes. WiMAX orthogonal frequency division multiple access (OFDMA) system specifies the orthogonal frequency division multiplexing (OFDM) symbol mapping in a rectangular area manner. The rectangular mapping problem is known to be NP- complete. In this paper, we propose a novel Cognitive Radio-based QoS support framework and Cognitive Radio-based Self-optimizing temporal-spectrum block (TSB) scheduling which is a joint sub-carrier allocation and symbol-duration scheduling cum mapping scheme in WiMAX point-to-multipoint (PMP) WirelessHUMAN™ OFDMA systems. The proposed solution can intelligently explore unused spectrums and spread the system to non-active spectrums to significantly improve the capacity of the system and provide guar- anteed QoS to real-time traffic. Extensive simulation experiments have been carried out to evaluate the performance of our proposal. The simulation results show that our proposed solution can expand the capacity of the WiMAX system while providing QoS to real-time and non-real-time traffic. Ó 2010 Elsevier B.V. All rights reserved. 1. Introduction Recently, broadband wireless access becomes ubiquitous. This makes the already heavily crowded radio spectrum much scarcer [1]. Cognitive radio (CR) is a prom- ising technology to alleviate the increasing stress on the fixed radio spectrum. In cognitive radio based opportunis- tic spectrum access (OSA) networks, the secondary (unli- censed) users can periodically sense and identify available channels which are referred to as white spaces (WS) as the parts of the spectrum not in active use by the primary users. Based on the results of spectrum sens- ing, the secondary users dynamically tune its transceivers to the identified WSs to access the wireless channel with- out disturbing the communications of the primary users. Broadband wireless access networks, e.g. WiMAX [2] systems, have received a lot of attention from academic and industrial researchers in the last few years as WiMAX systems have the ability to provide broadband wireless ac- cess and the potential ability to compete with existing wired and wireless networks. WiMAX can support four dif- ferent QoS levels. QoS provisioning to such heterogeneous traffic with integrated real-time and non-real-time traffic is an important issue in the deployment of WiMAX sys- tems. To tackle the QoS provisioning issue, one of the important QoS support mechanisms is the scheduling scheme. However, the detail of scheduling scheme has been left undefined in the IEEE 802.16d standard. Scheduling scheme is essential in the provisioning of guaranteed QoS parameters, such as packet delay, packet 1389-1286/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.comnet.2010.12.003 ⇑ Corresponding author. Tel.: +65 67838100. E-mail addresses: LU0002NG@ntu.edu.sg (J. Lu), Maode_Ma@pmail. ntu.edu.sg (M. Ma). Computer Networks 55 (2011) 1291–1309 Contents lists available at ScienceDirect Computer Networks journal homepage: www.elsevier.com/locate/comnet