## 1 Introduction  
Spectrum aggregation (or carrier aggregation) is considered a key enabler for next-generation communication networks, which can meet or even exceed the IMT-Advanced requirement for large transmission bandwidth (40 MHz-100 MHz) and high peak data rate (500 Mbps in the uplink and 1 Gbps in the downlink). In order to meet both the requirements for transmission bandwidth and the utilization of IMT bands, all IMT-Advanced candidate technologies are expected to support spectrum aggregation, within either contiguous or discontinuous spectrum bands [1]. In spectrum aggregation (SA) technology, two or more component carriers (CCs) of different bandwidths in different bands can be aggregated (up to 100 MHz with five CCs of 20 MHz) to support wider transmission bandwidth between the E-UTRAN NodeB (eNB) and the user equipment (UE) [2]. The introduction of SA has required the introduction of new functionalities and modifications to radio resource management (RRM) [3]. With the broadband wireless professional communications stepping into its start-up period, a project called broadband wireless trunking (BWT) was launched in China [4]. SA is one of the key techniques of the BWT. In terms of SA, BWT has some special aspects that are different from those of a mobile cellular system, including lacking enough spectrum bands for broadband data transmission. So, the technique of cognitive radio (CR) is introduced in BWT for SA. CR is considered one of the prominent techniques to improve the spectrum utilization [5] and it is also the key enabling technology that enables next-generation communication networks to utilize the spectrum more efficiently in an opportunistic fashion without interfering with the primary users [6; 7; 8]. Therefore, CR-based spectrum aggregation is getting more attention. Amounts of resource scheduling schemes for spectrum aggregation have been proposed in the literature, and these schemes can all be applied to spectrum-aggregation-based communication systems for different performance indicators. Although the aforementioned resource scheduling schemes focus on the different performance indicators to improve the performance of SA, it is worth noting that these performance indicators are not enough to guarantee good system performance. The current resource scheduling schemes for spectrum aggregation have not taken the users' delay requirement into account. For the BWT system, low transmission latency is the most important performance requirement [4]. Real-time communication and response is one of major technological challenges as we develop the BWT system. Due to this challenge in the development of the BWT system, the current scheduler structures and resource scheduling schemes become questionable and are not suitable for CR-based SA in the BWT system. To satisfy the requirement for low transmission latency of BWT, it is desirable to investigate a new resource scheduling scheme for CR-based SA by taking into account the delay requirement, which motivates this work. In this paper, we propose a novel resource configuration and switching scheme to meet the challenge of delay requirements in the CR-based SA system, called a component carrier configuration and switching scheme for real-time traffic (RT-CCCS). As a case study, we choose an orthogonal frequency division multiple access (OFDMA)-based wireless communication system for the evaluation of the proposed scheme. Typically SUs are capable of spectrum sensing, but the current spectrum sensing methods cannot guarantee perfect detection of the presence of the primary users (PUs), meaning false alarms and misdetections are unavoidable in real scenarios. False alarms result in less utilization of the spectrum, whereas misdetections result in collisions with the PU transmission. Amore appropriate approach for improving the sensing performance of a single user involves outsourcing the spectrum sensing to a low-cost dedicated sensor network [9], which exploits the location diversity of the sensor nodes and improves sensing accuracy and reliability [10].