Abstract—This paper develops a multiple channel assignment model, which allows to take advantage of spectrum opportunities in cognitive radio networks in the most efficient way. The developed scheme allows making several assignments of available and frequency adjacent channel, which require a bigger bandwidth, under an equality environment. The hybrid assignment model it is made by two algorithms, one that makes the ranking and selects available frequency channels and the other one in charge of establishing the Max-Min Fairness for not restrict the spectrum opportunities for all the other secondary users, who also claim to make transmissions. Measurements made were done for average bandwidth, average delay, as well as fairness computation for several channel assignments. Reached results were evaluated with experimental spectrum occupational data from captured GSM frequency band. The developed model shows evidence of improvement in spectrum opportunity use and a wider average transmission bandwidth for each secondary user, maintaining equality criteria in channel assignment. Keywords—Bandwidth, fairness, multichannel, secondary users. I. INTRODUCTION OGNITIVE RADIO NETWORKS (CRN) encounter optimization needs for spectrum optimization in wireless networks. This is interpreted as an opportunity for the improvement of the user service level in wireless technologies, creating an opportunity to use the available spectrum and then improving the service level for wireless technology users, making an opportunistic use of available spectrum and therefore improving spectrum efficiency [1], [2]. This opportunistic access in which the secondary user (SU) could make use of the licensed spectrum, until the primary user (PU) requires again that spectrum part which SU is using. In this scenario is necessary that SU moves to another free licensed spectrum; this mobility type is called Spectrum Handoff. This procedure could be defined as a process where the cognitive radio user (SU) changes his operating frequency, when the channel conditions are degraded or when a PU appears, as the first is using a licensed channel [3]. One significant difference of the current paper, when compared with most related work in the literature, is the fact to make multichannel assignments for SU that develop Hans R. Márquez is with the Department of Master of Science in Information and Communications at Universidad Distrital Francisco José de Caldas., Cra. 7 No. 40B–53, Bogotá, Colombia (e-mail: hans.marquez.ramos@gmail.com.co). Cesar Hernandez is with the Universidad Distrital Francisco José de Caldas., Cra. 7 No. 40B-53, Bogota, Colombia (Corresponding author, Phone: +573112186635; e-mail: cahernandezs@udistrital.edu.co). Ingrid Páez is with the Faculty of Engineering of the Universidad Nacional de Colombia, Cra. 45 No. 26–85, Bogota, Colombia (e-mail: ippaezp@unal.edu.co). applications in real time over a single channel, for those applications which could sustain delays. Even though, the fact of assigning several channels to a unique SU, could impact in a significant way, equality criteria on a SU interested in using these resources, as all SUs have an interest in transmission. In order to solve the former problem, fairness criteria are implemented to make an equality assignment of available resources among all secondary users in accordance to the application type (real time or best effort) For the development of these criteria, literature exposes several algorithms, even though one of the most widely used is the max-min fairness. This algorithm develops an equality process in recourse assignment. In the same way, it is essential to know which channels are the best to be used by secondary users and these ones make possible Fairness criteria. The present paper is structured as it follows: In Section II related papers are presented; in Section III, development of the model is described; in Section IV, results are shown and finally in Section V, conclusions are drawn. II. RELATED WORK In [4] it is proposed a protocol called RC-MAC which makes integration without any problem, useful cycle and assignment work for central receptor, yielding a high throughput, without energetic efficiency sacrifice. The way in which they handle a lot of traffic, which could be generated or triggered by one event, this protocol, takes advantage of the data compilation as a subjacent tree at WSN (Wireless Sensor Networks) and in the same way multichannel technique supported by radio frequency devices under IEEE standard 802.15.4. By observing the time in packet processing at low cost sensor nodes, a planning model was designed which guarantees Fairness between origin nodes without throughput sacrificing. Finally, it is demonstrated that throughput and Fairness are improved in a significant way under many loads, under central receptor planning. In [5] is presented an optimization problem in the radio resource assignment in the cell communication systems, both for tolerant users to delays as for those who demand transmissions in real time. This optimization problem was modeled through functions of the logarithmic and sigmoid utility. Optimization was done under PF criteria in order to make a maximum of utility in these network types, meanwhile user assignment, taking into account, quality for application of service requirements an temporary efficiency. In research done by [6] a framework is designed for opportunistic administration on multiple wireless channels. With a realistic channel model, any user sub-conduct could be Multichannel Scheme under Max-Min Fairness Environment for Cognitive Radio Networks Hans R. Márquez, Cesar Hernández, Ingrid Páez C World Academy of Science, Engineering and Technology International Journal of Electronics and Communication Engineering Vol:9, No:10, 2015 1174 International Scholarly and Scientific Research & Innovation 9(10) 2015 scholar.waset.org/1307-6892/10002747 International Science Index, Electronics and Communication Engineering Vol:9, No:10, 2015 waset.org/Publication/10002747